Correction of near-infrared spectra based on square voltage measurements

Abstract

A spectroscopic device (110) is proposed for obtaining spectroscopic information of at least one object (112), the spectroscopic device (110) comprising the following components: i. at least one light source (114) for generating illumination light (116) for illuminating the object (112), the light source (114) including at least one light emitting diode (118) and at least one luminescent material (120) for photoconverting primary light generated by the light emitting diode (118); ii. at least one detector (128) for detecting detection light (130) from the object (112); iii. at least one driving unit (138) for electrically driving the light source (114); iv. at least one measuring unit (139) for generating at least one information relating to at least one electrically measurable quantity, in particular the forward voltage required to drive the light-emitting diode (118); and v. at least one evaluation unit (136) for evaluating at least one detector signal generated by the detector (128) and deriving spectral information of the object (112) from the detector signal, the at least one evaluation unit (136) being configured to take into account information about at least one electrically measurable quantity, in particular a positive voltage, when deriving the spectral information from the detector signal.

Description

[Technical Field]

[0001] The present invention relates to a spectroscopic device for obtaining spectral information of at least one object, in particular a spectroscopic device used for analyzing a sample, and a method for obtaining spectral information of at least one object. Furthermore, the present invention relates to a computer program, a computer-readable storage medium, and a non-transitory computer-readable storage medium. Such devices and methods are generally used for research or monitoring purposes, in particular in the infrared (IR) spectral region, in particular the near-infrared (NIR) spectral region, and in the visible (VIS) spectral region, e.g., spectral regions that mimic human color vision. However, further applications are possible. [Background technology]

[0002] Spectroscopic devices are known as efficient tools for obtaining the spectral characteristics of an object when it emits, illuminates, reflects, or absorbs light, and thus can aid in the analysis of samples and other tasks where information about the object's spectral characteristics is important.

[0003] Typically, in a spectroscopic device, spectral information is acquired via one or more detectors and one or more wavelength-selective optical elements (e.g., one or more dispersive optical elements, bandpass filters, prisms, gratings, interferometers, etc.). The detectors can include any type of light-sensitive element, such as single or multiple pixel detectors, line detectors, or array detectors with one- or two-dimensional pixel arrangements. Furthermore, the spectroscopic device may include one or more light sources. Thus, tunable light sources (e.g., lasers) and / or broadband emitting light sources (e.g., halogen gas-filled bulbs and / or hot wires) are typically used in spectroscopy. However, additionally or alternatively, other light sources have also been proposed in the visible light range, such as light-emitting diodes (LEDs).

[0004] For example, Patent Document 1 (US 2010 / 208261 A1) describes an apparatus for measuring at least one optical property of a sample. The apparatus includes an adjustable excitation light source for irradiating the sample with excitation light. The apparatus further includes a detector for detecting detection light emitted from the sample. The excitation light source includes a light emitting diode array, at least a portion of which is configured as a single crystal light emitting diode array. The single crystal light emitting diode array includes at least three light emitting diodes, each having a different emission spectrum.

[0005] Patent document 2 (US 8,164,050 B2) describes a multi-channel light source assembly for downhole spectroscopy having individual light sources that generate optical signals across a range of wavelengths. A combining assembly optically combines the generated signals into a combined signal, and a routing assembly splits the combined signal into a reference channel and a measurement channel. Control circuitry electrically connected to the light sources modulates each light source at a unique or independent frequency during operation.

[0006] Furthermore, US Pat. No. 7,061,618 B2 describes an integrated spectroscopy system, in some examples of which an integrated tunable detector is provided using one or more Fabry-Perot tunable filters, while in other examples an integrated tunable light source is used, combining one or more diodes, such as superlaminant light emitting diodes (SLEDs), with a Fabry-Perot tunable filter or etalon.

[0007] Furthermore, US Pat. No. 5,475,221 A describes an optical device that uses an array of light-emitting diodes controlled in a multiplexing manner to replace conventional broadband light sources in devices such as spectrometers.

[0008] Generally, spectroscopic devices are subject to various internal and external influences, including environmental factors, which can affect the results of spectroscopic measurements. To correct or compensate for these influences, various calibration and / or correction methods are known. These calibration methods may be performed once or multiple times under laboratory conditions, for example, by the manufacturer. However, several online calibration techniques are also known, which can be performed by performing one or more correction and / or calibration steps between or during two spectroscopic measurements.

[0009] Patent document 4 (US 09360366 B1) discloses a self-referencing spectrometer that uses a shared aperture as an optical input and simultaneously measures the optical spectrum of a physical object with automatic calibration. The simultaneous measurement and self-calibration capabilities allow the spectrometer to be used as a spectrometer that can be attached to a mobile computing device without the need for offline calibration using an external reference light source. The acquired spectral information and image data can be distributed via a wireless communication network through the mobile computing device.

[0010] Patent document 5 (DE 102014013848 B4) discloses a NIR microspectrometer, microspectrometer system, and calibration method for battery-powered devices that overcomes the aforementioned system configuration's lack of miniaturization and portability limitations. The miniaturized NIR spectrometer is designed without active temperature stabilization. Instead, according to the invention, the spectral sensitivity function (QEλ = f(T); measured with an integrated temperature sensor) is recorded at multiple levels within the expected operating temperature range as part of a factory temperature calibration process.

[0011] Patent Document 6 (WO 2019 / 191698 A2) relates to a self-referencing spectrometer for simultaneously measuring a background or reference spectral density and a sample or other spectral density. The self-referencing spectrometer includes an interferometer optically coupled to receive an input beam and generate a first interference beam along a first optical path and a second interference beam along a second optical path, where each interference beam is generated prior to output from the interferometer. The spectrometer further includes a detector for simultaneously detecting a first interference signal generated from the first interference beam and a second interference signal generated from the second interference beam, and a processing unit configured to process the first interference signal and the second interference signal and use the second interference signal as a reference signal in processing the first interference signal.

[0012] Patent Document 7 (US 20210293620 A1) discloses a spectrometer. The spectrometer includes an illumination device that illuminates a spectroscopic measurement region; a detection unit that detects electromagnetic radiation from the spectroscopic measurement region; and a spectroscopic element disposed between the illumination device and the detection unit. The illumination device includes the following components: a light-emitting diode having a first central wavelength and designed to emit a first electromagnetic wave having a first spectrum; and a light-emitting element that converts a first component of the first electromagnetic wave having the first spectrum into a second electromagnetic wave having a second spectrum. The first central wavelength is 550 nm, 3000 nm, or a value between 550 nm and 3000 nm. The first spectrum and the second spectrum overlap.

[0013] Patent document 8 (US 06667802 B2) discloses a method for calibrating a spectroscopic inspection system, the method comprising the steps of providing a plurality of packages, each package containing a group of items, each group of items having a known composition, measuring the reflectance values ​​of each group of items to obtain a reference reflectance value set, normalizing the reference reflectance value set to create a normalized reference reflectance value set, and storing the normalized reference reflectance value set.

[0014] Patent Document 9 (US 06717669 B2) discloses an auto-calibration spectrometer and method for measuring the transmittance or reflectance of a sample over a long period of time without requiring calibration. Reflection and transmission spectrometers, as well as an auto-calibration method for use therewith, are disclosed. A lens or similar optical element is used to focus light onto a sample, reflect the light irradiated onto the sample, and transmit the light reflected from the sample. Monitoring the light reflected from the first lens and the sample provides very useful information about the system response versus time. The light reflected from the first lens and the sample is monitored and used to correct for changes in the system over time.

[0015] Patent document 10 (US 09448114 B2) discloses a spectrometer including multiple isolated optical channels. These isolated optical channels are composed of multiple isolated optical paths. The isolated optical paths reduce crosstalk between the optical paths, improving resolution while shortening the overall length of the spectrometer. In many embodiments, the isolated optical paths include isolated parallel optical paths, which can significantly shorten the overall length of the device. In many embodiments, each isolated optical path runs from a filter in a filter array, through a lens in a lens array, through a channel in a support array, and to a region of a sensor array. Each region of the sensor array includes multiple sensor elements, and the position of each sensor element corresponds to the wavelength of light received based on the angle of light received at that position, the focal length of the lens, and the center wavelength of the filter.

[0016] Patent document 11 (US 2013 / 093936 A1) discloses an energy dispersive device, spectrometer, and method for assessing the composition of a material in situ without requiring specialized training or expensive equipment. The energy dispersive device or spectrometer can be used in combination with a digital camera or smartphone. The device of this invention includes a stack of single or double dispersive diffraction gratings that can be rotated about its normal, resulting in multiple diffraction orders that can be used to make meaningful measurements and determinations about the qualitative or quantitative properties of the material.

[0017] Patent document 12 (US 2018 / 172510 A1) describes a system for analyzing food in a kitchen appliance, the function of which may include one or more of identifying the food, determining the nutritional information of the food, and / or monitoring the cooking state of the food. The system may include a spectrometer device integrated into the kitchen appliance (e.g., an oven) or a spectrometer device located remotely from the kitchen appliance. The system may include a compound parabolic condenser or focusing lens connected to a spectrometer module and an illumination module of the device. The system may also include a compound parabolic condenser or focusing lens connected to each spectrometer module and illumination module, respectively, for analyzing food at close range.

[0018] Patent document 13 (US 2011 / 241549 A1) describes a light generation system including a plurality of solid state light emitting elements (SSEs) and a stability control system for controlling the spectral stability of the SSEs. In a particular case, the stability control system includes the following components: a power regulator for adjusting the power supplied to a subset of the SSEs; a constant current circuit connected to the power regulator and supplying a constant current to the subset of SSEs; a current regulation setpoint connected to the constant current circuit; and a controller configured to set the regulation setpoint based on measured data regarding the state of the SSEs.

[0019] Despite the advantages achieved by known methods and devices, several technical challenges remain in the field of spectroscopy and spectroscopic devices, particularly in the near-infrared region. Therefore, calibration techniques that correct for various effects are desirable, especially for on-line correction of these effects at in-situ spectroscopic measurement sites. In particular, temperature is known to have a significant impact on the results and accuracy of spectroscopic measurements. Temperature changes can be caused by external factors, such as changes in environmental temperature. Additionally, or alternatively, temperature changes can occur due to internal factors, such as electrical currents or electrical resistances (e.g., due to electrical power consumption) within the spectroscopic device. These temperature changes can occur on short-term scales or in the form of long-term drift. Furthermore, it should be considered that temperature changes do not necessarily occur on a global scale, or that the entire spectroscopic device need not be in thermal equilibrium. Therefore, local temperature changes can occur in locations that are difficult to monitor, such as within the spectroscopic device or at interfaces (e.g., semiconductor interfaces) within components of the spectroscopic device. Furthermore, the temperature dependence of the system can change. For example, even if the temperature is constant, the system may behave differently over time. This may be due to deterioration, aging, or changes in the optical or electrical interfaces due to heavy use, etc. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] US 2010 / 208261 A1 [Patent Document 2] US 8,164,050 B2 [Patent Document 3] US 7,061,618 B2 [Patent Document 4] US 09360366 B1 [Patent Document 5] DE 102014013848 B4 [Patent Document 6] WO 2019 / 191698 A2 [Patent Document 7] US 20210293620 A1 [Patent Document 8] US 06667802 B2 [Patent Document 9] US 06717669 B2 [Patent Document 10] US 09448114 B2 [Patent Document 11] US 2013 / 093936 A1 [Patent Document 12] US 2018 / 172510 A1 [Patent Document 13] US 2011 / 241549 A1 Summary of the Invention [Problem to be solved by the invention]

[0021] It is therefore desirable to provide, at least in part, a method that at least partially overcomes the above-mentioned technical problems and at least substantially avoids the drawbacks of known methods and devices. In particular, it is an object of the present invention to provide a spectroscopic device and a method for obtaining spectral information of at least one object that are capable of correcting for external and / or internal influences, such as temperature changes. [Means for solving the problem]

[0022] This problem is solved by a spectroscopic device for obtaining spectral information about at least one object, a corresponding method, a computer program, a computer-readable storage medium and a non-transitory computer-readable storage medium, which have the features of the independent claims. Advantageous embodiments having the features of the independent claims are set out in the dependent claims and throughout the specification.

[0023] In a first aspect, a spectroscopic device for obtaining spectral information from at least one object is disclosed, the spectroscopic device including: i. at least one light source for generating illumination light for illuminating an object, the light source including at least one light emitting diode and at least one luminescent material for photoconversion of primary light generated by the light emitting diode, and in particular, the illumination light is any of a combination of the primary light, light generated by photoconversion by the luminescent material, and light generated by photoconversion by the luminescent material; ii. at least one detector for detecting detection light detected from the object; iii. at least one driving unit for electrically driving the light source; iv. At least one measuring unit for generating at least one electrically measurable quantity, at least one item, in particular at least one information regarding the forward voltage required to drive the light-emitting diode, in particular under a predetermined electrical current passing through the light-emitting diode; and v. At least one evaluation unit for evaluating at least one detector signal generated by the detector and deriving spectral information of the object from the detector signal, the evaluation unit being configured to take into account information about electrically measurable quantities, in particular positive voltages, when deriving the spectral information from the detector signal.

[0024] The light source may include, in particular, a phosphor light-emitting diode or a phosphor LED. The light-emitting diode may have a main emission wavelength range, at least a portion of which is located within the wavelength range of 250 nm to 940 nm. The light-emitting diode may have a main emission wavelength range, at least a portion of which is located within the wavelength range of 420 nm to 460 nm, more particularly within the range of 440 nm to 455 nm, and even more particularly 440 nm. The illumination light has a spectral range, at least a portion of which is located within the near-infrared spectral range, in particular within the range of 1 μm to 3 μm, preferably within the range of 1.3 μm to 2.5 μm, and even more preferably within the range of 1.5 μm to 2.2 μm. In particular, the ratio of the central wavelength of the main emission range generated by the light-emitting diode to the central wavelength of the emission range of the phosphor LED is within the range of 0.1 to 0.8, preferably within the range of 0.12 to 0.7, and even more preferably within the range of 0.14 to 0.65.

[0025] The evaluation unit may be configured to determine at least one correction from information about the electrically measurable quantity, in particular information about the forward voltage, in particular based on a model describing the spectral characteristics of the light source as a function of the forward voltage. The evaluation unit may further be configured to correct at least one detection signal using the correction. The correction may in particular include multiplying the at least one detection signal by at least one correction factor. The evaluation unit may in particular be configured to derive spectral information using the corrected detector signals. The detector may in particular be configured to generate detector signals in at least one spectral range of light from the object, preferably at least two different spectral ranges (in particular sequentially and simultaneously). The evaluation unit may be configured to individually correct the detector signals in the different spectral ranges and derive spectral information by combining the individually corrected detector signals. For example, the detector may be configured to generate detector signals in a single wavelength range. In particular, the spectroscopic device, in particular the detector, may be sensitive to a wavelength of 1500 nm, also known as the water band. Additionally or alternatively, the spectroscopic device, and in particular the detector, may be configured to be sensitive to more than one spectral range.

[0026] The detector may include an array of light-sensitive elements. Each light-sensitive element may be configured to generate at least one detector signal. The evaluation unit may be configured to correct each detector signal individually and to combine the detector signals to derive spectral information. The spectrometer device may be configured such that the light-sensitive elements are sensitive to different spectral ranges of light from the object. The spectrometer may include at least one filter element disposed in the optical path of the light from the object. The filter element may be configured such that each light-sensitive element is exposed to a respective spectral range of light from the object.

[0027] The spectroscopic device may include at least one wavelength-selective element, particularly at least one of a wavelength-selective element arranged in the optical path of the illumination light and a wavelength-selective element arranged in the optical path of the detection light, particularly selected from the group consisting of a variable wavelength-selective element and a wavelength-selective element having a fixed transmission spectrum.

[0028] In a further aspect, a method for obtaining spectral information of at least one object is disclosed. The method includes the following steps, which may be performed in the given order, although different orders are also possible. In particular, one, more, or all of the method steps may be performed once or repeatedly. Furthermore, the method steps may be performed sequentially, or alternatively, one or more method steps may be performed in a timed overlapping, parallel, or combined manner. The method may include additional method steps not listed. The method includes the following steps: a. electrically driving at least one light source using at least one driving unit, the light source including at least one light emitting diode and at least one luminescent material for photoconversion of primary light generated by the light emitting diode; b. generating, using at least one measuring unit, at least one piece of information relating to at least one electrically measurable quantity (in particular a forward voltage), which information is necessary for driving the light-emitting diode; c. illuminating the object with illumination light generated by the light source; d. detecting the detection light from the object using at least one detector; and e. Evaluating at least one detector signal generated by the detector using at least one evaluation unit and deriving spectral information of the object from the detector signal, wherein when deriving the spectral information from the detector signal, information about electrically measurable quantities, in particular positive voltages, is taken into account when deriving the spectral information from the detector signal.

[0029] This method may be implemented in particular in accordance with the spectroscopic device of the present invention, such as any of the embodiments described above and / or any of the embodiments described in detail below.

[0030] The method can be performed in particular online, e.g., in the field. The spectroscopic device can in particular be a portable spectroscopic device that can be used in the field. In particular, the spectroscopic device can be part of or attachable to a mobile device (e.g., a laptop, a tablet, a mobile phone (e.g., a smartphone), a smart watch, and / or a wearable computer (e.g., a body-worn computer)).

[0031] As explained above, in step e., at least one correction value may be determined from an item of information relating to the electrically measurable quantity, in particular the forward voltage. Furthermore, at least one detection signal may be corrected using the correction. The correction may be based on a model describing the spectral characteristics of the light source as a function of the electrically measurable quantity, in particular the forward voltage. This correction may in particular involve multiplying at least one detection signal by at least one correction factor. The corrected detection signal can be used to derive spectral information. The detector may generate detection signals for at least two different spectral ranges of light emitted from the object. The detector spectral ranges may overlap or may not intersect with each other. The detector may generate detection signals for at least two different spectral ranges of light emitted from the object sequentially or simultaneously. The method, in particular step e., may comprise separately correcting the detector signals for different spectral ranges and deriving the spectral information by combining the separately corrected detector signals. Additionally or alternatively, the detector may be configured to generate a signal for at least one spectral range, for example a single spectral range (eg, a narrow band centered around a target wavelength).

[0032] The detector may particularly include an array of light-sensitive elements. Each light-sensitive element may be configured to generate at least one detector signal. The method, particularly step e., may also include correcting each detector signal individually and combining the detector signals to derive spectral information. The light-sensitive elements may particularly be sensitive to different spectral ranges of light from the object.

[0033] The spectroscopic device may also include at least one filter element disposed in the optical path of the light from the object, the filter element being configured such that each light sensitive element is exposed to a respective spectral range of the light from the object.

[0034] The method may be fully or partly computer-implemented, so step e. of the method may be computer-implemented.

[0035] In further aspects, computer programs, computer readable recording media, and non-transitory computer readable recording media are disclosed, which include instructions that, when executed by an evaluation unit of a spectroscopic device of the present invention, cause the evaluation unit to operate to perform the method of the present invention, e.g., according to any of the embodiments described above or in more detail below (e.g., according to any one of the examples described above or in more detail below).

[0036] In this specification, the terms "have," "include," "contain," or any grammatical variants of these terms are used in an inclusive sense. Thus, these terms can refer to both a situation in which the subject matter described in the context has no further features other than the features introduced by these terms, and a situation in which one or more further features are present. For example, the expressions "A has B," "A includes B," and "A encompasses B" can refer to both a situation in which no other elements are present in A other than B (i.e., a situation in which A is composed solely and exclusively of B), and a situation in which one or more additional elements are present in A other than B (e.g., element C, elements C and D, or further elements).

[0037] Furthermore, the use of "at least one," "one or more," or similar phrases indicating that a feature or element may be present more than one time will typically only be used once to introduce that feature or element. In most cases, the phrase "at least one" or "one or more" will not be repeated when referring to that feature or element, even if the feature or element is present more than one time.

[0038] Furthermore, in this specification, the terms "preferably," "more preferably," "particularly," "more particularly," "particularly," "more particularly," or similar terms are used to indicate optional features and do not limit the possibilities of substitution. Features introduced with these terms are therefore optional features and are not intended to limit the scope of the claims in any way. As one skilled in the art will recognize, the present invention can be practiced using alternative features. Similarly, features introduced with "in an embodiment of the invention" or similar phrases are intended as optional features, without any limitations on alternative embodiments of the invention, on the scope of the invention, or on the possibility of combining features introduced in this way with other optional or required features of the invention.

[0039] The term "spectroscopic device" as used herein is a broad term and is intended to have the meaning commonly understood by those skilled in the art, without being limited to a specific or customized meaning. In particular, the term includes, but is not limited to, an optical device configured to acquire at least one spectral information about at least one object. Specifically, the at least one spectral information represents at least one optical or optically measurable characteristic determined as a function of wavelength or a plurality of different wavelengths. More specifically, the optical or optically measurable characteristic and the at least one spectral information may relate to characteristics characterizing at least one of transmission, absorption, reflection, or emission of the at least one object. These characteristics may be measured when the object is alone or after being illuminated with external light. The at least one optical characteristic is determined for one or more wavelengths. The spectroscopic device particularly forms a device for recording signal intensities at wavelengths corresponding to a spectrum or a portion thereof (e.g., a wavelength interval), and the signal intensities are provided as electrical signals that can be used for further evaluation.

[0040] The spectroscopic device may be or include, for example, a device that allows the measurement of at least one spectrum, for example, a measurement of spectral flux (as a function of wavelength or detection wavelength). The spectrum may be acquired, for example, in absolute units or relative units (relative to at least one reference measurement). Thus, for example, the acquisition of at least one spectrum may be performed for measuring spectral flux (units W / nm) or for measuring a spectrum for at least one reference substance (units 1), which describes a material property, for example, reflectance versus wavelength. Additionally or alternatively, reference measurements may be performed based on a reference light source, an optical reference path, a calculated reference signal (e.g., a reference signal calculated from literature), and / or a reference device.

[0041] In particular, the at least one spectroscopic device may be a diffuse reflectance spectroscopic device configured to obtain spectral information from light diffusely reflected by at least one object (e.g., at least one sample). Additionally or alternatively, the at least one spectroscopic device may be or include an absorption spectrometer and / or a transmission spectrometer. In particular, measuring the spectrum with the spectroscopic device may include measuring absorption in a transmission configuration. In particular, the spectroscopic device can be configured to measure absorption in a transmission configuration. However, as noted above, other types of spectroscopic devices are also possible.

[0042] The at least one spectroscopic device can include at least one light source, which can be, for example, a tunable light source, a light source having at least one fixed emission wavelength, or a broadband light source, as described in detail below. The spectroscopic device can further include at least one detector, as described in detail below, configured to detect light transmitted, reflected, or emitted from the at least one object. The spectroscopic device can also include at least one wavelength-selective element, such as a grating, prism, or filter (e.g., a filter with a variable length whose transmission characteristics change in a lateral extension direction), as described in detail below. The wavelength-selective element is used to separate the incident light into a spectrum of constituent wavelength signals and measure the respective intensities using a detector (e.g., a detector having a detector array), as described in detail below.

[0043] The spectroscopic device may particularly be a portable spectroscopic device. The term "portable" as used herein is a broad term and is intended to have the meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. In particular, the term refers to, but is not limited to, the property of at least one object being movable by human force (e.g., by a single user). Specifically, objects characterized by the term "portable" include those having a weight of not more than 10 kg, particularly not more than 5 kg, more particularly not more than 1 kg, or not more than 500 g. Additionally or alternatively, the dimensions of an object characterized by the term "portable" may be configured to not exceed 0.3 m in any dimension, particularly not more than 0.2 m in any dimension. Objects may particularly have a volume of 0.03 m or less. 3 Not exceeding 0.01m 3 Not exceeding, more specifically, 0.001 m 3 Not exceeding 500mm 3In particular, for example, portable spectroscopic devices include those having dimensions of 10 mm x 10 mm x 5 mm. In particular, portable spectroscopic devices include those that are part of or attachable to a mobile device, such as a laptop, tablet, mobile phone (including a smartphone), smart watch, or wearable computer (also called wearable), for example a computer worn on the wrist (such as a wristband or watch). In particular, the weight of a spectroscopic device, in particular a portable spectroscopic device, is in the range of 1 g to 100 g, more particularly in the range of 1 g to 10 g.

[0044] The term "spectral information," also referred to herein as "spectroscopic data" or "spectroscopic data item," is a broad term intended to have a general meaning commonly understood by those skilled in the art and is not limited to any particular or customized meaning. This term is not particularly limited and may refer to information about at least one object and / or radiation emitted from at least one object, e.g., information characterizing at least one optical property of the object, and more particularly, at least one piece of information characterizing, e.g., quantifying or qualifying, at least one transmission, absorption, reflection, or emission of the object. For example, the at least one piece of spectral information may include at least one piece of intensity information, e.g., information about the intensity of light transmitted, absorbed, reflected, or emitted by the object, e.g., as a function of one or more wavelengths, e.g., wavelength ranges, in wavelength or wavelength subranges. In particular, the intensity information may correspond to or be derived from a signal intensity, particularly an electrical signal, recorded by a spectroscopic device for a spectral wavelength or wavelength range.

[0045] The spectrometer device can be configured to acquire a spectrum, or a portion thereof, of detected light propagating from the object to the spectrometer. The spectrum can describe radiant units of spectral flux, e.g., in watts per nanometer (W / nm), or can be expressed in other units, e.g., as a function of wavelength of the detected light. Thus, the spectrum can describe the optical power of light in a specific wavelength band, e.g., in the near-infrared (NIR) spectral range. The spectrum can include one or more optical variables (e.g., power spectral density, electrical signals derived from optical measurements, etc.) as a function of wavelength. The spectrum can, for example, represent the power spectral density and / or spectral flux of the object (e.g., sample), or can represent the transmittance and / or reflectance of the object (e.g., sample) relative to a reference sample (e.g., transmittance and / or reflectance).

[0046] The spectrum may, for example, include at least one measurable optical variable or property of the detected light and / or the object, and in particular may be defined as a function that depends on the illuminating light and / or the detected light. For example, the at least one measurable optical variable or property may also include at least one radiant quantity, such as spectral density, power spectral density, spectral flux, radiant flux, radiant intensity, spectral radiant intensity, illuminance, or spectral irradiance. In particular, for example, the spectroscopic device, in particular the detector, may measure the power of the object in watts per square meter (W / m 2 ) and more specifically, watts per square meter per nanometer ( W / m 2 The spectral irradiance in watts per nanometer (W / nm) can also be measured. Based on the measured quantity, and taking into account the area of ​​the detector, the spectral flux in watts per nanometer (W / nm) and / or the radiant flux in watts (W) can also be calculated.

[0047] The term "object" as used herein is a broad term and is intended to have a general meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. The term "object" is not particularly limited and refers to any object selected from living and non-living things. For example, at least one object may include one or more articles and / or one or more portions of articles, where the at least one article or at least one portion thereof may include at least one component that provides a spectrum suitable for investigation. Additionally or alternatively, the object may be or include one or more living organisms and / or parts thereof, such as a human body part (e.g., a user) and / or an animal. The object may particularly include at least one sample that can be analyzed completely or partially by spectroscopy. For example, the object may be or include one or more of the following: human skin or animal skin; edible objects such as fruit; plastics and fibers. The term "light," as used further herein, is a broad term and is intended to have the general meaning commonly understood by those skilled in the art, without being limited to a specific or customized meaning. In particular, the term may refer to electromagnetic waves including one or more of the infrared, visible, or ultraviolet spectral ranges. Here, the "ultraviolet spectral range" generally refers to electromagnetic waves having wavelengths between 1 nm and 380 nm, preferably between 100 nm and 380 nm. Furthermore, in accordance with, in part, the ISO-21348 standard in effect as of the date of this document, the term "visible spectral range" generally refers to the spectral range between 380 nm and 760 nm. The "infrared spectral range" (IR) generally refers to electromagnetic radiation having wavelengths between 760 nm and 1000 μm, with the range from 760 nm to 1.5 μm commonly referred to as the "near-infrared spectral range" (NIR), the range from 1.5 μm to 15 μm as the "mid-infrared spectral range" (MidIR), and the range from 15 μm to 1000 μm as the "far-infrared spectral range" (FIR). Preferably, the light used in typical applications of the present invention is light in the infrared (IR) spectral range, more preferably light in the near-infrared (NIR) and / or mid-infrared spectral range (MidIR), particularly light having wavelengths between 1 μm and 5 μm, preferably between 1 μm and 3 μm. This is because many properties related to the physical or chemical makeup of substances can be derived from the near-infrared spectral range. However, it should be noted that spectroscopy in other spectral ranges is also possible and within the scope of the present invention.

[0048] Thus, the terms "light source" or "illumination source" as used herein are broad terms and are intended to have the general meaning commonly understood by those skilled in the art, and are not limited to any specific or customized meaning. The terms are not particularly limited and may refer to any device that generates or provides light within the above definition. The light source may be at least one electrically powered light source, including, for example, an electrically powered light source.

[0049] As will be described in more detail below, the light sources can generally be realized in a variety of forms. Thus, for example, the light sources may be part of the spectroscopic device, contained within the housing of the spectroscopic device. Alternatively, or additionally, at least one light source may be located outside the housing as a separate light source. The light sources may be located remotely from the object and arranged to illuminate the object.

[0050] In spectroscopy, it is necessary to distinguish between various light sources and light paths. In the context of the present invention, light propagating from a light source to an object is first referred to as "illumination light" or "illumination light." Light propagating from the object to a detector is secondarily referred to as "detected light." Detected light may include at least one of illumination light reflected by the object, illumination light scattered by the object, illumination light transmitted by the object, and luminescence light generated by the object (e.g., fluorescent light or phosphorescent light generated by the object after optical, electrical, or acoustic stimulation by the illumination light). Thus, detected light may be generated directly or indirectly through illumination of the object by the illumination light.

[0051] Furthermore, within the light source itself, it is also possible to distinguish between different types of light sources, such as primary light sources and secondary light sources, as will be explained in more detail below. Thus, as will be explained in more detail below, light referred to as "primary light" or "pump light" may be generated by a primary light source, such as at least one light emitting diode (LED), and then converted to "secondary light" by photoconversion (e.g., conversion through one or more phosphor materials). The illumination light may be or include a primary light source or a portion thereof, a secondary light source or a portion thereof, or a mixture of both.

[0052] Thus, the term "illuminating" as used herein is intended to be broad and to have the meaning commonly understood by those skilled in the art, and is not limited to any particular or customized meaning. The term is not particularly limited and may refer to the process of exposing at least one element to light.

[0053] As mentioned above, the light source includes at least one light emitting diode and at least one luminescent material that photoconverts the primary light generated by the light emitting diode. Specifically, the illumination light may be a combination of the primary light and the light generated by photoconversion by the luminescent material, or the light generated by photoconversion of the luminescent material (also called secondary light).

[0054] The term "light-emitting diode" or abbreviation "LED" used herein is a broad term and is intended to have the general meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. This term may refer to, without limitation, an optoelectronic semiconductor device that emits light when an electrical current passes through the device. Optoelectronic semiconductor devices may be configured to generate light through one or more physical processes, such as spontaneous emission, induced emission, or decay of a metastable excited state. For example, light-emitting diodes may include one or more of the following: light-emitting diodes based on spontaneous emission (particularly organic light-emitting diodes), light-emitting diodes based on superluminescence (sLEDs), or laser diodes (LDs). Hereinafter, the abbreviation "LED" is used to refer to any type of light-emitting diode, without limiting possible embodiments of light-emitting diodes to any of the aforementioned physical principles or configurations. Specifically, an LED may include at least two layers of semiconductor material, where light is generated at the interface of the at least two layers of semiconductor material, particularly by recombination of positive and negative electrical charges, e.g., electron-hole recombination. The at least two layers of semiconductor material may have different electrical properties, for example, when at least one layer is an n-type doped semiconductor material and at least one layer is a p-type doped semiconductor material. Thus, for example, the LED may include at least one pn junction and / or at least one pin arrangement. However, other device structures are also possible. The at least one semiconductor material may in particular be or include at least one inorganic semiconductor material. However, organic semiconductor materials may also be used additionally or alternatively.

[0055] In general, an LED converts electrical current into light, and specifically may convert it into primary light, more specifically blue primary light (discussed in more detail below). Therefore, the LED may specifically be a blue LED. The LED may be configured to generate primary light (also called pump light). Therefore, the LED may also be referred to as a "pump LED." The LED may include at least one LED chip and / or at least one LED die. Therefore, the semiconductor element of the LED may include a bare LED chip.

[0056] Various LEDs suitable for generating primary light are well known to those skilled in the art and are applicable to the present invention. In particular, pn diodes may be used. For example, one or more LEDs selected from indium gallium nitride (InGaN)-based LEDs, gallium nitride (GaN)-based LEDs, LEDs based on InGaN / GaN alloys or combinations thereof, or other LEDs may be used. Additionally or alternatively, quantum well LEDs may be used, for example, one or more quantum well LEDs based on InGaN. Additionally or alternatively, superluminescent LEDs (sLEDs) and / or quantum cascade lasers may be used.

[0057] The term "luminescence" as used herein is a broad term and is intended to have the general meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. This term specifically includes, but is not limited to, the process of spontaneous emission of light by a substance without thermal origin. In particular, luminescence may refer to "cold body radiation." More specifically, luminescence may be initiated or excited by light irradiation, in which case luminescence is also referred to as "photoluminescence." In the context of the present invention, the ability of a substance to emit light is expressed by the adjective "luminescent." At least one luminescent material may specifically refer to a photoluminescent material, i.e., a material capable of emitting light after absorbing photons or excitation light. Specifically, the luminescent material may have a positive Stokes shift, which may generally refer to the fact that secondary light is red-shifted relative to primary light.

[0058] The at least one luminescent material may thus form at least one converter (also called optical converter) that converts primary light into secondary light having spectral characteristics different from those of the primary light. In particular, the spectral width of the secondary light may be wider than that of the primary light, and / or the emission center of the secondary light may be shifted (especially red-shifted) with respect to the primary light. In particular, the at least one luminescent material may have absorption in the ultraviolet and / or blue spectral region and emission in the near-infrared and / or infrared spectral region. Thus, in general, the luminescent material or converter may also form at least one component of a phosphor LED that converts primary or pump light in the blue spectral region into light of longer wavelengths, for example, in the near-infrared or infrared spectral region.

[0059] Various types of conversion and / or emission are known and can be used in the context of the present invention. Thus, in particular, conversion can occur via dipole-allowed transitions (fluorescence) in the luminescent material and / or via dipole-forbidden (and therefore long-lived) transitions in the luminescent material, the latter also commonly referred to as fluorescence.

[0060] The luminescent material may therefore in particular form at least one converter or light converter. The luminescent material may also form at least one of a converter platelet on the LED, a luminescent coating (in particular a phosphor coating) or a phosphor coating on the LED. The luminescent material may, for example, comprise one or more of the following materials: cerium-doped YAG (YAG:Ce 3+ 、 or Y3Al5O 12 :Ce 3+ ); rare earth doped sialic acid; copper and aluminum doped zinc sulfide (ZnS:Cu,Al).

[0061] The LED and the luminescent material together may form a so-called "phosphor LED." Therefore, the term "phosphor light-emitting diode" or abbreviated "phosphor LED" as used herein is a broad term and is intended to have the meaning commonly understood by those skilled in the art, without being limited to any particular or customized meaning. This term may specifically, but is not limited to, refer to the combination of a light-emitting diode (LED) configured to generate primary or pump light and at least one luminescent material, referred to as a "phosphor," configured for photoconversion of the primary light generated by the LED. Phosphor LEDs may also form packaged LED light sources that include an LED die (e.g., a blue LED emitting blue pump light) and a phosphor (e.g., configured to fully or partially cover the LED and convert the primary or blue light to light with different spectral characteristics, particularly near-infrared light). Generally, phosphor LEDs may be encapsulated in a single housing or may be unencapsulated. Thus, the LED and at least one phosphor for photoconversion of the primary light generated by the LED may be housed in a common housing. However, the LED may alternatively be an unpackaged or bare LED, and may be fully or partially coated with luminescent material (for example, by disposing one or more layers of luminescent material on the LED die). Phosphor LEDs generally form the light emitting element or light source by themselves.

[0062] In a light source, particularly a phosphor LED, at least one luminescent material may be disposed in a position that allows heat transfer from the light emitting diode to the luminescent material. More particularly, the luminescent material may be disposed in a position that allows heat transfer by thermal radiation and / or thermal conduction, more preferably by thermal conduction. For example, the luminescent material may be in thermal and / or physical contact with the light emitting diode. For example, the luminescent material may form one or more coatings or layers in contact with or adjacent to the light emitting diode, and in contact with one or more of the semiconductor materials of the light emitting diode. This generally allows the temperature of the luminescent material to be coupled to the temperature of the light emitting diode.

[0063] In particular, the at least one luminescent material may form at least one layer. Generally, various alternatives are possible for disposing the luminescent material relative to the light emitting diode, either alone or in combination. First, the luminescent material (e.g., at least one layer of luminescent material, e.g., phosphor) may be disposed directly on the light-emitting diode, also referred to as "direct attachment" (this includes, for example, cases where there is no material between the LED and the luminescent material, or where there are one or more transparent materials (e.g., one or more transparent materials disposed between the LED and the luminescent material, and which are particularly transparent to the primary light)). Thus, for example, a coating of luminescent material may be disposed directly or indirectly on the LED. Additionally or alternatively, the luminescent material may, for example, form at least one converter body (e.g., at least one converter disk), which may be disposed on top of the LED (e.g., by adhesively fastening the converter body to the LED). Additionally or alternatively, the luminescent material may be arranged so as to be remotely disposed, in which case the primary light from the LED must pass through an intermediate optical path before reaching the luminescent material. This arrangement may be referred to as "remote placement" or "remote phosphor." For example, the luminescent material in the remote location may form a solid body or converter body, such as a disk or converter disk. Furthermore, in the case of a remote location, the luminescent material may also function as a coating. In particular, the phosphor may be coated on a light-transmitting object (e.g., a thin plate made of or fabricated from glass or plastic, such as a glass substrate or module window). Alternatively, a reflective surface may be coated with the phosphor. This may be a smooth or rough mirror surface including and / or fabricated from a substrate of a highly reflective material (e.g., silicon), or a smooth or rough surface (e.g., glass or plastic) coated with gold, silver, aluminum, or chromium. One or more optical elements, including lenses, prisms, gratings, mirrors, apertures, or combinations thereof, may be disposed in the intermediate optical path. This allows, for example, an optical system with image-forming properties to be disposed in the intermediate optical path between the LED and the luminescent material.This may, for example, allow the main light to be focused or bundled onto the converter body.

[0064] As further described above, the spectroscopic device includes at least one detector configured to detect detected light (e.g., diffusely reflected light) detected from the object. The verb "detect" as used herein is a broad term and is intended to have a general meaning commonly understood by those skilled in the art, without being limited to a specific or customized meaning. This term specifically includes, but is not limited to, a process of qualitatively and / or quantitatively measuring, monitoring, or determining at least one parameter (e.g., a physical parameter, a chemical parameter, a biological parameter, etc.). Specifically, the physical parameter is or includes an electrical parameter. Accordingly, the term "detector" as used herein is a broad term and is intended to have a general meaning commonly understood by those skilled in the art, without being limited to a specific or customized meaning. In particular, this term refers to, but is not limited to, any apparatus (device) for quantitatively and / or qualitatively measuring, measuring, or monitoring at least one parameter (e.g., a physical parameter, a chemical parameter, or a biological parameter). The detector may also be configured to generate at least one detector signal, more particularly at least one electrical detector signal (an analog and / or digital detector signal, a detector signal providing information about at least one parameter measured by the detector, etc.). The detector signal may be provided directly or indirectly from the detector to an evaluation unit, whereby the detector and the evaluation unit may be directly or indirectly connected. The detector signal may be used as a "raw" detector signal, or may be processed or pre-processed (e.g., processed by filtering, etc.) before further use. Thus, the detector may also include at least one processing unit and / or at least one pre-processing unit, such as at least one of an amplifier, an analog-to-digital converter, an electrical filter, a Fourier transform, etc.

[0065] In one embodiment, the detector is configured to detect light propagating from the object to the spectroscopic device, or more specifically to the detector of the spectroscopic device; according to the terminology described above, this light is referred to as "detected light." Therefore, in particular, the detector may be or may include at least one optical detector. The optical detector may be configured to measure at least one optical parameter, such as the intensity and / or power of light irradiating at least one photosensitive area of ​​the detector. More particularly, the optical detector may include at least one photosensitive element and / or at least one optical sensor, such as at least one of a photodiode, a photocell, a photosensitive resistor, a phototransistor, a thermoelectric sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier, or a bolometer. The detector may thus be configured to generate at least one detection signal, more particularly at least one electrical detection signal, in the above sense, providing information about at least one optical parameter, such as the power and / or intensity of light irradiating the detector or the photosensitive area of ​​the detector.

[0066] The detector may comprise a single light-sensitive element or region, or a plurality of light-sensitive elements or regions. In particular, the detector may be or comprise at least one detector array, more particularly an array of light-sensitive elements, as will be explained in more detail below. Each light-sensitive element may comprise at least one light-sensitive region adapted to generate an electrical signal depending on the intensity of the incident light, which electrical signal may in particular be provided to an evaluation unit, as will be explained in more detail below.

[0067] The photosensitive region included in each photosensitive element may be a single, uniform photosensitive region specifically configured to receive incident light that illuminates the individual photosensitive element, although other arrangements of photosensitive elements are also contemplated.

[0068] The array of light-sensitive elements can be designed to generate a detection signal (preferably an electronic signal) related to the intensity of incident light impinging on each individual light-sensitive element. The detection signal can be an analog signal and / or a digital signal. The electronic signals of adjacent pixelated sensors can therefore be generated simultaneously or sequentially in time. For example, during a row or line scan, it is possible to generate a sequence of electronic signals corresponding to a series of linearly arranged individual light-sensitive elements. Furthermore, the individual light-sensitive elements are preferably active pixel sensors, which can be adapted to amplify the electronic signals before supplying them to the evaluation unit. For this purpose, the detector can also include one or more signal processing devices (e.g., one or more filters and / or analog-to-digital converters) for processing and / or preprocessing the electronic signals.

[0069] When the detector includes an array of photosensitive elements, the detector can be selected, for example, from known pixel sensors, particularly pixelated organic camera elements, preferably pixelated organic camera chips, or pixelated inorganic camera elements, preferably pixelated inorganic camera chips, more preferably CCD or CMOS chips, which are currently commonly used in various cameras. Alternatively, the detector can generally be or include a photoconductor, particularly inorganic photoconductors, in particular PbS, PbSe, Ge, InGaAs, InGaAs, InSb, or HgCdTe. As a further alternative, it can also include at least one pyroelectric, bolometric, or thermophilic detector element. Thus, camera chips with a matrix of 1×N pixels or M×N pixels can be used, where M is less than 10 and N is in the range of 1 to 50, preferably 2 to 20, and more preferably 5 to 10. Furthermore, it is also possible to use a monochrome camera element, preferably a monochrome camera chip, which can be selected differently for each light-sensitive element according to the wavelengths that vary along the optical sensor sequence.

[0070] The array may therefore be adaptable to provide a plurality of electrical signals generated by the light sensitive regions of the light sensitive elements that make up the array. The electrical signals provided by the array of spectroscopic devices may be transmitted to an evaluation unit.

[0071] As further explained above, the at least one spectroscopic device includes at least one driving unit for electrically driving the light source, and the spectroscopic device includes at least one measurement unit configured to generate at least one information relating to at least one electrically measurable quantity, in particular a forward voltage required to drive the light emitting diode.

[0072] The term "drive" is used broadly herein and has its ordinary and customary meaning as commonly understood by those skilled in the art, without being limited to any special or customized meaning. In particular, this term refers to, but is not limited to, the process of providing at least one control parameter and / or electrical power to another device. Thus, the term "drive unit" as used herein is used broadly and has its ordinary and customary meaning as commonly understood by those skilled in the art, without being limited to any special or customized meaning. In particular, this term is not limited to, and may refer to any device or combination of devices that provides at least one control parameter and / or electrical power to another device (e.g., in this case, it may refer to a device that provides at least one light source). The term "measurement unit" is used broadly herein and has its ordinary and customary meaning as commonly understood by those skilled in the art, without being limited to any special or customized meaning. The term "measurement unit" may particularly, but not exclusively, denote any device or combination of devices configured to measure one or more electrical parameters of the electrical power supplied to a light source (particularly at least one light-emitting diode) and generate at least one piece of information related to an electrically measurable quantity (particularly a forward voltage). The measurement unit may also be an element of the driving unit and / or the evaluation unit. For example, the driving unit may be configured to measure and / or control one or more electrical parameters of the electrical power supplied to the light source (particularly at least one light-emitting diode). For example, the driving unit may be configured to supply an electrical current to the LED, and in particular to control the electrical current through the LED. In that case, by way of example, the driving unit may also be configured to adapt and measure the voltage supplied to the LED (this voltage is required to achieve a certain electrical current through the LED). The measurement unit (e.g., driving unit) may particularly include any one or more of the following: a current source, a voltage source, a current measuring device (e.g., an ampere meter), a voltage measuring device (e.g., a voltmeter), a power measuring device.In particular, the driving unit may include at least one current source for supplying at least one predetermined current to the LEDs, which may be configured to adjust or control the voltage applied to the LEDs to generate the predetermined current. The driving unit may also include one or more electrical components, such as, for example, an integrated circuit for driving the light source. The driving unit may be fully or partially integrated into the light source or may be separate from the light source.

[0073] The term "electrically measurable quantity" used herein is a broad term and is intended to have the meaning commonly understood by those skilled in the art, without being limited to a specific or customized meaning. In particular, this term may refer to, but is not limited to, an electrically measurable parameter required to drive a light-emitting diode. For example, the electrically measurable quantity may include at least one quantity selected from the following group: forward voltage, input power, current, resistance, inductance, capacitance, etc.

[0074] The term "forward voltage" is used broadly herein and is intended to have the general meaning commonly understood by those skilled in the art, without being limited to any particular or customized meaning. This term may refer to, without limitation, a voltage applied to an LED in a forward direction (e.g., a voltage to generate a predetermined electrical current through the LED by connecting the positive terminal of a voltage or current source to the p-layer of the LED and the negative terminal to the n-layer). For example, the predetermined current defining the forward voltage may be a current known to generate a predetermined light output from a light source and / or light-emitting diode. This predetermined current may be, in particular, in the range of 10 mA to 500 mA, more particularly, in the range of 100 mA to 300 mA. Additionally or alternatively, the term "forward voltage" may refer to the minimum voltage required to be applied to an LED in a forward direction (i.e., a voltage to generate a significant electrical current through the LED (e.g., a current equal to or greater than a minimum threshold value)). Specifically, the predetermined electrical current defined as the minimum electrical current may be applied to the LED. An example of a forward voltage is a voltage derived from the diode characteristics of an LED (specifically, a voltage derived from a graph in which the horizontal axis represents the voltage applied to the LED and the vertical axis represents the current). An example of a forward voltage is a voltage derived from a logarithmic plot of the diode characteristics of an LED (e.g., by identifying a break in the positive branch of the characteristic curve, or by identifying the voltage at the intersection of the horizontal or voltage axis with a line characterizing the steep portion of the positive branch). Therefore, a forward voltage is generally a voltage applied to an LED in the forward direction (from p to n) to cause electrical current to flow through the diode. The forward voltage may depend on the bandgap of the LED. Therefore, generally, an LED whose primary emission wavelength or range of primary emission wavelengths is in the short wavelength region (e.g., the blue spectral region) may require a higher forward voltage than an LED that emits light in the long wavelength region, such as red light. Forward voltage is sometimes referred to as a "forward bias" or "junction voltage." Forward voltage includes V F or V LED The symbol may also be used.

[0075] Thus, in general, the direction of electrical current in an LED may be defined as the "positive direction" when the current flows from the p-type doped layer to the n-type doped layer of the LED, and / or when the p-side or p-type doped layer of the LED is connected to the positive terminal of an electrical power source and the n-side or n-type doped layer is connected to the negative terminal of the electrical power source.

[0076] To generate at least one piece of information about at least one electrically measurable quantity (e.g., a forward voltage) necessary for driving the light-emitting diode, for example when driving the light-emitting diode with a predetermined electrical current in the forward direction, the measurement unit (e.g., as part of the driving unit) may also include one or more measuring devices or elements (e.g., one or more voltage measuring devices). The at least one piece of information about the at least one electrically measurable quantity, in particular the forward voltage, may be provided by the measurement unit in the form of at least one electrical signal and / or electrical information (e.g., including one or both of an analog signal and / or a digital signal). The electrical signal (e.g., the forward voltage) containing the at least one piece of information about the at least one electrically measurable quantity may be provided directly or indirectly to the evaluation unit. The electrical signal may be time-dependent or static.

[0077] As further explained above, the spectroscopic device includes at least one evaluation unit for evaluating at least one detector signal generated by the detector and deriving spectral information of the object from the detector signal. The term "evaluate" is used herein in a broad sense and has its ordinary meaning as commonly understood by those skilled in the art, without being limited to any special or customized meaning. In particular, this term refers to, but is not limited to, the process of processing at least one first piece of information to generate at least one second piece of information. Therefore, the term "evaluation unit" is used herein in a broad sense and has its ordinary meaning as commonly understood by those skilled in the art, without being limited to any special or customized meaning. The term "evaluation unit" may particularly, but not exclusively, refer to any device or combination of devices configured to evaluate or process at least one first item of information, thereby generating at least one second item of information. Thus, in particular, the evaluation unit may be configured to process at least one input signal, thereby generating at least one output signal. The at least one input signal may, for example, comprise at least one detector signal provided directly or indirectly from at least one detector, and may further comprise at least one signal provided directly or indirectly from a measuring unit, said signal comprising at least one item of information relating to at least one electrically measurable quantity, in particular a positive voltage.

[0078] For example, the evaluation unit may be or include one or more integrated circuits (e.g., one or more application specific integrated circuits (ASICs)) and / or one or more data processing devices (e.g., one or more computers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), preferably one or more microcomputers and / or microcontrollers). Additional components may also be included, such as one or more pre-processing and / or data acquisition devices, such as one or more devices for receiving and / or pre-processing the detector signals (e.g., one or more analog-to-digital converters (ADCs) and / or one or more filters). Furthermore, the evaluation unit may also include one or more data storage devices. Furthermore, the evaluation unit may also include one or more interfaces, such as one or more wireless interfaces and / or one or more wired interfaces.

[0079] The at least one evaluation unit may be adapted to execute at least one computer program, for example, the at least one computer program performing or supporting the step of generating an item of information. For example, at least one algorithm may be implemented, which uses the at least one detection signal and at least one piece of information on at least one electrically measurable quantity (especially the forward voltage) as input variables to perform a predetermined transformation for deriving spectral information on the object, for example, for deriving a corrected spectrum or for deriving at least one piece of spectral information describing at least one property of the object. For this purpose, the evaluation unit may in particular include at least one data processing device (also called processor), in particular an electronic data processing device, designed to evaluate the detection signal and the information on the at least one electrically measurable quantity (especially the forward voltage) to generate the desired information. The evaluation unit may use any process to generate the required information, for example, calculations and / or at least one stored and / or known relationship. The evaluation unit may be configured to perform at least one digital signal processing (DSP) technique, in particular at least one Fourier transform, on the primary detector signal or a secondary detector signal derived therefrom. Additionally or alternatively, the evaluation unit may be configured to perform one or more additional digital signal processing techniques, including, for example, windowing, filtering, a Goetzel algorithm, cross-correlation, or autocorrelation, on the primary detector signal or a secondary detector signal derived therefrom. In addition to information about the detector signal and the at least one electrically measurable quantity, in particular the forward voltage, one or more additional parameters and / or information may influence the relationship. The relationship may be determined empirically, analytically, or semi-empirically. For example, the relationship may comprise a model or calibration curve, at least one set of calibration curves, at least one function, or a combination of the above possibilities.The calibration curve(s) can also be stored in a data storage device and / or a table, for example in the form of a set of values ​​and their corresponding function values. Alternatively or additionally, at least one calibration curve can be stored in parameterized form and / or as a function. Separate relations for converting the detection signals into information items can also be used. Alternatively, at least one combined relation for processing the detection signals can be employed. Various possibilities are conceivable, and these can also be combined.

[0080] As mentioned above, the evaluation unit can also be configured, for example, by software programming, to determine at least one correction value from information about at least one electrically measurable quantity (particularly, this information relates to, for example, forward voltage). Thus, for example, the evaluation unit can be configured to determine a spectrum from at least one detector signal provided by the detector (the spectrum including a spectrum showing a luminous intensity or radiometric parameter as a function of wavelength). This spectrum can be corrected by applying at least one correction function (e.g., correction factor) to generate a corrected spectrum, where, for example, the correction factor is or includes at least one correction factor that is a function of the long wavelength of the detected light and at least one electrically measurable quantity (particularly, forward voltage). The detector signal can, for example, provide a signal that is a function of the wavelength of the detected light, whereby the correction factor can be used to multiply each function value of the detector signal by a corresponding correction factor that is determined by at least one electrically measurable quantity, particularly, forward voltage.

[0081] For example, the detector signal may include multiple detector signals that are at least a function of the wavelength of the detected light, and the signal may also depend on time, if necessary, including a time-dependent detector signal. These multiple detector signals may form a spectrum, including a digital or analog spectrum. For example, each detector signal summarizes information from a predetermined spectral range defined by the spectral resolution of the detector. As described below, the detector may also include multiple photosensitive elements, each sensitive to a different spectral range and / or exposed to different portions of the spectrum of the detected light. The totality of the detection signals of the photosensitive elements may form the detection signal, or may collectively define, for example, spectral information, a portion thereof, or a precursor thereof. Since the spectral range of sensitivity of each photosensitive element is known, the detector signals can be used to derive the intensity of the detected light for a detection wavelength. This is achieved by combining data pairs including the signal of each photosensitive element and the wavelength of sensitivity. Here, the signal of each photosensitive element is corrected using a correction factor for the corresponding wavelength. This correction factor is provided by the evaluation unit as a function of at least one electrically measurable quantity, in particular the forward voltage. However, it should be noted that other methods of generating spectral information are possible, such as sequentially exposing the same detector to different spectral regions of the detected light, for example, using a scannable wavelength-selective element, and correction of these sequentially measured spectra may be performed in a similar manner by appropriately correcting the spectra using correction factors as a function of wavelength.

[0082] Therefore, the term "correction," as generally used herein, is a broad term and is intended to have the general meaning commonly understood by those skilled in the art and is not limited to a specific or customized meaning. This term is not particularly limited and may refer to the process of correcting at least one item of interest or the correction thereof according to one or more pieces of information indicating parameters known to affect the item. Thus, a measured spectrum may be corrected so that the corrected spectrum corresponds to a spectrum under precisely known or standardized conditions (e.g., a spectrum under a specific temperature and / or a predetermined electrically measurable quantity, particularly a predetermined standard forward voltage). The corrected spectrum is then compared to a reference spectrum determined under precisely known or standardized conditions. For example, correction may involve modifying the measured spectrum contained in a detector signal to correspond to a predetermined electrically measurable quantity, particularly a predetermined standard forward voltage, and / or standard conditions under a predetermined temperature, required to drive a light-emitting diode. Thus, step v. may include correcting the measured spectrum derived from the detector signal to correspond to a corrected spectrum (particularly, a corrected spectrum estimated to be obtained under predetermined standard conditions), e.g., to a measured spectrum at a predetermined electrical measurement quantity required to drive the light-emitting diode, particularly a predetermined standard forward voltage, and / or a predetermined temperature. The standard conditions may be defined using appropriate conditions, e.g., using room temperature as the predetermined temperature and / or a specific measurable quantity required to drive the light-emitting diode, particularly a specific forward voltage measured under a predetermined forward current at room temperature, although other standard conditions are also possible.

[0083] One or more calibration measurements may be performed to determine the correction coefficient, particularly the correction function. Therefore, the correction may be based on one or more calibration measurements. For example, the calibration measurement may measure at least one detector signal using an electrically measurable quantity, particularly a forward voltage, as a parameter, and, if necessary, may also measure the detection wavelength as a parameter. As described above, at least one condition may be determined as a standard condition, such as at least one specific electrically measurable quantity, particularly at least one specific forward voltage, required to drive the light-emitting diode. For example, an electrically measurable quantity, particularly a forward voltage, measured at room temperature may be predetermined (e.g., for each wavelength) to define the standard condition. The correction coefficient may also be determined for each wavelength by determining the ratio of the detection signal measured for a specific electrically measurable quantity, particularly a specific forward voltage, to the detection signal measured for a predetermined standard electrically measurable quantity, particularly a standard forward voltage. Thus, if the information, particularly about the electrically measurable quantity, particularly the forward voltage, generated by the measurement unit, e.g., generated by the drive unit, deviates from a standard electrically measurable quantity, particularly the standard forward voltage, the correction factor can be selected so that the corrected detector signal corresponds to the detector signal measured under predetermined standard conditions, e.g., room temperature. Additionally or alternatively, the temperature can be intentionally changed, e.g., by setting or adjusting the temperature to two or more target temperatures. In particular, the standard conditions can include a set of two or more predefined target temperatures and / or a set of corresponding electrically measurable quantities (e.g., forward voltages). At each temperature, the electrically measurable quantity (e.g., forward voltages) and the detector signal can be measured (e.g., for each wavelength). The correction factor can then be determined as described above.

[0084] In particular, the correction can be based on a model describing the spectral characteristics of the light source, particularly as a function of forward voltage and / or temperature. The model can be empirical, semi-empirical, or theoretical. For example, as described in more detail below, the effect on the spectrum of changes in an electrically measurable quantity, particularly the forward voltage, required to drive the light-emitting diode can be measured by one or more calibration measurements, e.g., using a standardized or reference object and measuring the spectrum as a function of the electrically measurable quantity, particularly the forward voltage. The correction can then be determined, e.g., by using a particular electrically measurable quantity, particularly a particular forward voltage, as a reference and correcting spectra measured at other electrically measurable quantities, particularly other forward voltages, to match the standardized spectrum.

[0085] At least one model describing the change in the spectrum and / or spectral information of the object as a function of electrically measurable quantities, in particular positive voltage, and / or a model describing the corrections required to correct the spectrum and / or spectral information of the object as a function of electrically measurable quantities, in particular positive voltage, may also be determined in advance and may be stored, for example, in at least one data storage device of the spectroscopic device.

[0086] As explained further above, the evaluation unit may also be configured to correct at least one detector signal using a correction. For example, the evaluation unit may be configured, via software programming, to convert the detector signal (e.g., a spectrum derived therefrom) directly or indirectly into a corrected detector signal (e.g., a corrected spectrum). For example, as explained further above, the correction may include multiplying the at least one detector signal (i.e., the "raw" detector signal or a derivative thereof, e.g., a spectrum generated using the detector signal) by at least one correction factor. This may also allow for spectral correction taking into account electrically measurable quantities, in particular the forward voltage, required to drive the light-emitting diode as a correction parameter. The evaluation unit may particularly be configured to derive spectral information using the corrected detector signal.

[0087] For example, the detector may be configured to generate detection signals in at least one spectral range, in particular in at least two different spectral ranges of light emitted from the object, particularly configured to generate detection signals in at least one spectral range sequentially or simultaneously. For example, the detector configured as described above may include an array of light-sensitive elements, each of which may be sensitive to light in a different spectral range and / or configured to be exposed to light in a different spectral range. The evaluation unit may be configured to individually correct the detector signals in the different spectral ranges and to derive spectral information by combining the individually corrected detector signals. Thus, the individually corrected detector signals may be combined, for example, to generate a corrected spectrum.

[0088] Thus, in general, the detector may comprise an array of light-sensitive elements, each of which may be configured to generate at least one detector signal. The evaluation unit may generally be configured to correct each detector signal individually and to derive spectral information by combining the detector signals. Thus, in particular if each light-sensitive element is sensitive to or exposed to light in different spectral ranges (e.g., by one or more appropriate filters arranged in the detection light path), it is also possible to correct for each light-sensitive element individually using electrically measurable quantities (e.g., forward voltage) as correction parameters or temperature effects. As mentioned above, the photosensitive elements may be sensitive to different spectral ranges of light from the object. Different spectral sensitivities may be achieved by using photosensitive elements with inherently different spectral sensitivities, for example, by using different integrated filters and / or different light-sensitive materials (e.g., semiconductor materials). Additionally or alternatively, different spectral sensitivities may be achieved by placing one or more wavelength-selective elements, such as filters, gratings, prisms, or the like, in one or more optical paths of the detected light, such that different spectral components of the forward direction of the detected light from the object reach the respective photosensitive elements sequentially or simultaneously.

[0089] Therefore, in general, a spectroscopic device may also include at least one wavelength-selective element. As used herein, the term "wavelength-selective element" is a broad term and is intended to have the meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. This term is not particularly limited and may refer to any optical element that interacts differently with different spectral components of incident light, such as an optical element having at least one wavelength-dependent optical property, including at least one wavelength-dependent optical property selected from the list of reflectance, reflection direction, refractive index, refraction direction, absorption, transmittance, and refractive index.

[0090] Here, wavelength selection by the at least one wavelength-selecting element may be performed in at least one optical path of the illumination light, where the wavelength of illumination of the object is selected and / or changed (e.g., for the detector in general and / or for each photosensitive element), and / or in the detection optical path of the detection light, where the wavelength of detection is selected and / or changed. Thus, for example, the at least one wavelength-selecting element may include at least one of a wavelength-selecting element arranged in the optical path of the illumination light and a wavelength-selecting element arranged in the optical path of the detection light.

[0091] The wavelength-selective element may in particular be selected from the group of adjustable wavelength-selective elements and wavelength-selective elements with fixed transmission spectra. When an adjustable wavelength-selective element is used, it is possible, for example, to sequentially select different wavelength ranges. On the other hand, when a wavelength-selective element with fixed transmission spectra is used, the selection of the wavelength range is fixed, but may, for example, depend on the detection position. This makes it possible, for example, in the detection light path, to simultaneously expose different detectors and / or different light-sensitive elements of the detector to light of different spectral ranges.

[0092] Thus, as explained above, and by way of example, the at least one wavelength-selective element may include at least one of a filter, a grating, a prism, a plasmonic filter, a diffractive optical element, or a metamaterial. More specifically, the spectroscopic device may include at least one filter element disposed in the optical path of the light emanating from the object (i.e., the detected light), configured such that each light-sensitive element is exposed to a respective spectral range of the light emanating from the object. For example, a variable filter element, whose transmittance depends on its position on the filter element, may be used, and when the variable filter element is disposed above the array of light-sensitive elements, each light-sensitive element is exposed to a portion of the spectral range of the incident light, particularly the detected light from the object. Additionally or alternatively, the at least one wavelength-selective element may include at least one of the following elements: an array of individual bandpass filters, an array of patterned filters, a MEMS interferometer, or a MEMS Fabry-Perot interferometer. Still other elements are possible.

[0093] As further explained above, this method may be particularly implemented online in situ. The term "online" is used herein in a broad sense, meaning as it would normally be understood by a person skilled in the art, and is not limited to any particular or customized meaning. This term particularly refers to the nature of a process being performed as part of another process, including, for example, during another process, without the need for a separate initiation or activation by a user. Thus, specifically, the operation of correcting the detector signal using at least one piece of information related to an electrically measurable quantity, particularly a forward voltage, may be implemented as an online calibration or correction, without the need for a separate calibration process, when acquiring spectral information related to at least one object.

[0094] As explained in more detail above, the method according to any of the above embodiments and / or any of the embodiments explained in more detail below may be entirely or partially computer-controlled, computer-implemented, and / or computer-assisted, for example, by using one or more computer programs running on at least one processor (e.g., at least one processor within at least one processor of a spectroscopic device, e.g., at least one processor integrated within a detector and / or evaluation unit). In particular, as outlined above, step e. of the method may be computer-controlled, computer-implemented, or computer-assisted. However, it should be noted that other steps of the method may also be computer-controlled, computer-implemented, or computer-assisted. For example, this may be any one or more of steps a., b., c., and d.

[0095] In this specification, the terms "computer-readable data carrier", "computer-readable storage medium" and "non-transitory computer-readable medium" are broad terms and are intended to have the meanings that are commonly understood by those skilled in the art, without being limited to any specific or customized meaning. These terms may particularly refer to, but are not limited to, data storage means, especially non-transitory data storage means, such as hardware storage media that store computer-executable instructions. A computer-readable data carrier or storage media or computer-readable medium may in particular be or include storage media such as random access memory (RAM) and / or read-only memory (ROM).

[0096] The spectroscopic device and method of the present invention, in one or more embodiments described above and / or in one or more embodiments described in detail below, offers numerous advantages over similar devices and methods. In particular, it is possible to perform online correction or calibration for temperature changes, including local temperature changes within the light source, which may affect the light source's radiation characteristics. More particularly, electrically measurable quantities, particularly forward voltages, required to drive LEDs serve as reliable correction parameters and typically exhibit reproducible changes as a function of local temperature within phosphor LEDs, allowing for correction of detector signals, particularly spectra or information derived from such spectral information.

[0097] Furthermore, the use of phosphate LEDs in place of or in combination with conventional thermal emitters (e.g., tungsten-wire incandescent lamps) may offer several advantages. While thermal emitters generally offer flat spectra, low low-temperature dependence, and high power spectral density even in long wavelength regions (e.g., the near-infrared), thermal emitters are typically unsuitable for the fabrication of large-volume spectrometers. Therefore, the disadvantages of thermal emitters generally include the high complexity of their manufacturing process, low electrical-to-optical conversion efficiency, and physical limitations in miniaturization. The use of LEDs, particularly phosphor LEDs, may overcome these drawbacks. LEDs have proven to be reliable standardized light sources in the visible light region.

[0098] In the context of the present invention, a spectroscopic device comprising at least one light-emitting diode and at least one luminescent material or phosphor can also be used to provide a broadband light source using one or more phosphor LEDs. This can, for example, create a white light source or realize a broadband light source in the infrared range, especially the near-infrared range. The phosphor can convert photons with shorter wavelengths (and therefore higher energy) into photons with longer wavelengths (and therefore lower energy), for example by transferring part of the energy of the primary photons to a phosphor material (e.g., a phosphor lattice). The remaining lower energy can cause the emission of longer-wavelength photons.

[0099] Thus, the luminescent material may be configured to absorb one or more primary photons generated by the light-emitting diode and may emit one or more secondary photons in response to this absorption. The emission of the secondary photons may occur immediately or after a delayed or decay time. Thus, as discussed above, the luminescent material may be or include at least one of a fluorescent material and a phosphorescent material. Fluorescence may cause the luminescent material to emit secondary light (e.g., long-wavelength light) for a characteristic lifetime τ (tau) after the primary light, such as a short-wavelength or high-energy pump light, is turned off, e.g., due to forbidden quantum optical transitions or forbidden dipole transitions. Thus, specifically, in the luminescent material, the emission of secondary light may occur via forbidden transitions (e.g., forbidden dipole transitions) that have a longer lifetime than spontaneous dipole-allowed transitions, as is the case in many fluorescent materials.

[0100] Specifically, as mentioned above, luminescent materials, especially fluorescent materials, that absorb in the blue spectral region and emit in the infrared spectral region may be used. For example, luminescent materials capable of converting blue primary or pump light having a wavelength of 440 nm into near-infrared secondary light (e.g., secondary light having a wavelength in the 1-3 μm range, preferably 1.3-2.5 μm, more preferably 1.5-2.2 μm) may be used. Additionally or alternatively, the primary or pump light may be generated by an infrared LED having a wavelength in the 850-940 nm range, which may then be converted by the luminescent material into near-infrared secondary light (having a wavelength in the 1-3 μm range, preferably 1.3-2.5 μm, more preferably 1.5-2.2 μm range).

[0101] A phosphor LED includes at least one light emitting diode and at least one phosphor material and can be realized as a single element. Thus, technically, a phosphor LED may include multiple subcomponents.

[0102] First, a phosphor LED may include at least one functional element, such as an LED die having at least one junction (e.g., at least one pn junction) between at least two semiconductor regions, in which primary light (e.g., short-wavelength excitation light, e.g., in the blue spectral region) can be generated.

[0103] Furthermore, a fluorescent LED may include at least one luminescent material, in particular at least one fluorescent material, which is particularly disposed directly above the LED die and converts primary light (in particular excitation light) into secondary light (in particular long wavelength near infrared light).

[0104] Furthermore, fluorescent LEDs can also include at least one substrate (base material), specifically at least one electrically insulating substrate. Thus, for example, fluorescent LEDs can also include at least one ceramic substrate. The at least one substrate can also be configured to hold at least one LED die and at least one luminescent material. Furthermore, the at least one substrate can hold or include one or more electrical connection components, such as one or more contact pads and / or one or more electrical leads (e.g., one or more metal contacts and / or one or more metal leads). Furthermore, the substrate (e.g., ceramic substrate) can also be configured to function as a heat sink. Heat is generated in both the LED die and the luminescent material due to the limited conversion of electrical energy to light energy, and can also be generated within the luminescent material (e.g., during the conversion process). The heat can be dissipated within the substrate, such as a ceramic substrate.

[0105] The spectroscopic device using at least one LED can also be configured to operate in a continuous wave (CW) mode and / or preferably to apply at least one modulation driving scheme to improve the accuracy and reliability of the measurements. Thus, for example, the at least one driving unit can be configured to apply a modulation driving scheme to the LED, and the evaluation device can be configured to take the modulation driving scheme into account when deriving at least one spectral information from the at least one detector signal. For example, lock-in techniques, filter techniques, or other means known to those skilled in the art can be applied.

[0106] Therefore, the spectrometer device can also be configured to apply a modulation drive scheme to the LED to compensate for the DC background of the detector or to reduce detector noise, for example, a bandpass filter can be applied to the detector signal to remove the DC component.

[0107] Illumination light generated by a light source, particularly a phosphor LED, can be directed to illuminate the sample. For example, one or more mirrors can optionally be used to direct the illumination light. Detected light (e.g., reflected light) from the object can be directed to a detector, optionally using one or more optical components. For example, one or more wavelength-selective elements (e.g., dispersive elements) can be used to split the detected light into its spectral components.

[0108] The detector may record one or more detection signals, for example, using readout electronics integrated into the spectroscopic device, and in particular, using one or both of the detector and the evaluation device. The readout electronics may also include, for example, one or more signal processing devices. Thus, as described above, for evaluation by the evaluation device, the "raw" detector signal may be used, or one or more secondary detector signals derived therefrom (e.g., one or more filtered detector signals) may be used. Furthermore, at least one detector signal (primary or secondary) may be combined with wavelength-related information (e.g., derived from the number of photosensitive elements in the array of photosensitive elements from which the detector signal was derived), which is known to have been exposed to a particular wavelength within a particular wavelength range. In the context of the present invention, particularly in the context of evaluation of a detection signal by a detection signal evaluation unit, the options of evaluating the raw detection signal and / or the secondary detection signal (e.g., preprocessed detection signal, processed detection signal, or combined detection signal) are feasible. However, the present invention is particularly useful for correcting the "raw" detection signal, which indicates the signal intensity relative to the detection wavelength. Other options are possible.

[0109] For example, the detector signals (e.g., by the detector itself and / or the evaluation unit) may be processed or pre-processed into secondary detector signals by applying one or more Fourier transforms. For example, a fast Fourier transform (FFT) may be applied. From the processed secondary detector signals, at least one spectral information may be derived by software running in the evaluation unit. For example, the Fourier transform of the detector signals may be read by software in the spectroscopic device, in particular the evaluation device, and post-processed into spectral information of the object.

[0110] As noted above, LEDs and phosphor LEDs can also provide efficient, dimmable light sources for implementing specific evaluation schemes and reducing noise and artifacts. Temperature variations within the light source, particularly within the LED, can also be fully or partially compensated for by using at least one electrically measurable quantity, particularly the forward voltage, as a correction or calibration parameter. Thus, for a typical LED used herein, when operated at the maximum voltage and current the LED can withstand, the temperature of the various components of the light source, particularly the LED, can vary over a wide temperature range. For example, a typical operating current can range from 2 mA to 1000 mA, typically 10 mA to 300 mA. For example, the forward voltage can range from 1.5 V to 3.5 V, typically 2.25 V to 3 V. Thus, for example, under maximum operating conditions, the light-emitting element junction temperature can reach 135°C. The operating case temperature can range from -40°C to 135°C, and the emitter storage temperature can range from -40°C to 125°C. The electrostatic discharge (ESD) sensitivity of the LED may be 250 V according to standard ANSI / ESDA / JEDEC JS-001-2012. These typical parameters represent a wide range of temperature variations that may affect the spectral information obtained from the target by the spectroscopic device. Other parameters and parameter ranges are possible.

[0111] It is generally known that phosphor LEDs produce different spectra when the composition of the luminescent material, e.g., the phosphor composition, is different. Typically, each phosphor LED has multiple peaks in its spectrum, which spans a wide wavelength range. However, even when the same current is applied to a phosphor LED, its spectral characteristics and the spectrum itself can change with temperature. These changes include shifts in the emission peak, broadening or narrowing of the spectrum, and increases or decreases in emission intensity. In many cases, emission at certain wavelengths is more affected than emission at other wavelengths. Therefore, within the spectrum, there are specific center wavelengths where the power (especially the power spectral density) is independent of temperature changes. Each wavelength has a temperature coefficient for increasing or decreasing power. Therefore, the shape of the spectrum changes with temperature. Individual temperature correction of the spectrum at different wavelengths can also be performed by using electrically measurable quantities, particularly forward voltage, as correction parameters. Therefore, as described above, the evaluation unit can be configured to individually correct detector signals in different spectral ranges and derive spectral information by combining the individually corrected detector signals. More particularly, as mentioned above, this individual correction can be performed using an array of light-sensitive elements, where each light-sensitive element is configured to generate at least one detection signal, and each detection signal can be individually corrected using an electrically measurable quantity, in particular the forward voltage, as a correction parameter. Finally, the corrected detection signals can be combined to derive the spectral information.

[0112] By using electrically measurable quantities, especially the forward voltage, as correction parameters, temperature changes and the individual characteristics of phosphor LEDs can be corrected. For example, if the same current is applied to an LED, the forward voltage of the LED usually decreases as the temperature increases. Each type of LED has its own characteristic curve of forward voltage vs. temperature. Usually, the forward voltage of an LED decreases linearly with increasing temperature, e.g., 1·10 -4 From 1·10 -3 The gradient of the V / K range is shown.

[0113] Furthermore, spectroscopic devices and methods can take into account the characteristics of the luminescent material used in the light source. Therefore, as mentioned above, there is typically a delay between the absorption of at least one primary photon by the luminescent material and the emission of at least one secondary photon by the luminescent material. This delay is characterized by a so-called "characteristic time constant" τ, also referred to as the "time constant," "decay time," or "saturation time." As is well known to experts, the term "time constant" is used herein in a broad sense and is intended to have the general meaning commonly understood by those skilled in the art, without being limited to any specific or customized meaning. In processes where the rate or probability of a process, such as the emission of a photon, is proportional to the distribution of one or more states or process states, the distribution typically varies exponentially. The time constant τ in these processes may determine the 1 / e time of the process. For luminescent materials or converters, particularly phosphors, two different time constants may exist. The first time constant may represent the typical time until the emission of converted light reaches saturation. The second time constant may represent the typical time for the luminescent material or converter to decay (afterglow).

[0114] Typical time constants for phosphor conversion elements lie in the range of 0.1 ms to <10 ms. The time constants usually differ between different phosphor LEDs or different luminescent materials or phosphor elements. Phosphor elements emitting shorter wavelengths generally exhibit smaller time constants. Furthermore, the decay constant τ d and the growth constant τ g may be wavelength dependent.

[0115] The time constant is usually extracted from the step response of the optical signal obtained by applying and blocking a forward current.

[0116] After interrupting the forward current, the signal or light emission typically decays according to equation (1):

number

[0117] After switching on the forward current, the signal or light emission grows according to equation (2):

number

[0118] In both equations (1) and (2), S is the optical signal level at the time the forward current is applied / cut off. max is the optical signal level reached at t>>5.

[0119] Another characteristic of LEDs is the dependence of light output power on forward current. In general, increasing the input current increases the power that an LED can accept. The shape (e.g., slope) of the light output vs. forward current curve is a characteristic of each individual LED.

[0120] As described above, by using electrically measurable quantities, especially forward voltage, as control or correction parameters for spectroscopic measurements, efficient and reliable online correction or online calibration can be realized. This overcomes various challenges associated with typical spectrometers and their calibration. Specifically, in a typical spectroscopic process, the instrument response is calibrated by a reference measurement using a spectrometer, so the measurement result only provides information about the sample. However, if the optical components of the spectrometer device are changed between the reference and sample measurements, the sample information will be affected by the system change and may be distorted. In particular, the optical spectrum S of the light source Ls (λ) is the optical spectrum S LS,Ref (λ)) and the actual sample measurement (optical spectrum S LS,Sample (λ)), the spectral information of the object or sample is disguised. This is because the spectrum is the ratio S Ls (λ), S LS,Sample(λ) usually deviates. For phosphor LEDs, the situation is more complicated. This is because the spectrum of a phosphor LED is a combination of the spectrum of the LED and the spectrum of the luminescent material. The two components of a phosphor LED may be affected differently by temperature changes. Therefore, the spectrum of a phosphor LED is usually expressed by equation (3):

number

[0121] where S Ls (λ, T pn ,T p ) is the wavelength λ and the LED pn junction temperature T pn , and the temperature of the phosphor T p represents the spectrum of the light source LS with parameters S blue (λ,T pn ) represents the spectrum of the LED (e.g., blue LED), and S phosphor (λ,T p ) represents the spectrum of a light-emitting material (e.g., a phosphor).

[0122] Both subcomponents, the LED and the luminescent material, have their own independent temperature responses, so a change or shift in system temperature, or a change or shift in ambient temperature (especially between reference and sample measurements), will typically affect both the LED junction and the luminescent material, thereby affecting the spectrum.

[0123] The present invention may solve this problem in an efficient and reliable manner. Therefore, reliable correction parameters are provided, such as at least one piece of information about an electrically measurable quantity, in particular the forward voltage (the forward voltage itself and / or at least one other piece of information derived directly or indirectly from the forward voltage, e.g., a pre-processed value of the forward voltage), or other electrically measurable quantities necessary for driving a light-emitting diode, such as input power, current, resistance, inductance, capacitance, etc. When deriving spectral information from a detection signal, various temperature changes may be corrected by taking into account at least one piece of information about an electrically measurable quantity, in particular the forward voltage. This allows a self-referencing scheme to be applied, in which internal parameters (i.e., electrically measurable quantities, in particular the forward voltage) can be used for reference, in particular online. Below, this scheme will be exemplarily described using the forward voltage as an example of an electrically measurable quantity necessary for driving a light-emitting diode. Without being bound by this theory, this is because the temperature T of the light-emitting material is a function of the temperature T of the light-emitting material. p and the LED pn junction temperature T pn This is because there is a fixed dependency between:

number

[0124] Furthermore, the forward voltage U of the pn junction F and temperature T pn There are certain dependencies between:

number

[0125] Using these dependencies, a model can be created that takes into account the entire light source, and this model is pn It is based on the temperature alone, not on the combined junction and phosphor temperatures.

[0126] Junction temperature T pn is the forward voltage U FThis allows the radiation spectrum of a light source to be described by:

number

[0127] Therefore, the emission spectrum of the light source is a function of wavelength and forward voltage. This function may be determined, for example, empirically, semi-empirically, or theoretically. This function may be determined by performing a calibration process one or more times and measuring the forward voltage, for example, measuring intensity versus wavelength. This may allow one or more calibration curves to be determined and taken into account in the evaluation step. Therefore, measuring the forward voltage during a reference or sample measurement or a single measurement can efficiently correct for temperature effects.

[0128] For example, as described above, the optical spectrum of the light source before and after interaction with the object can be described as a function of the forward voltage as shown in equation (6) above. To correct the emission spectrum, for example, the emission spectrum can be measured using at least one reference forward voltage U F,Ref For example, this reference forward voltage may be the forward voltage expected or measured at a particular reference temperature (e.g., room temperature). Additionally or alternatively, the forward voltage at one or more other reference temperatures (e.g., housing temperature, heat sink temperature, or other system-specific temperature) may be used.

[0129] The correction includes at least one positive voltage-dependent correction factor or correction function k(λ,U F ) is used:

number

[0130] As shown, the correction function k(λ,U F ) is the wavelength λ and the forward voltage U FThe correction function may be a function of . This correction function may be determined by one or more calibration measurements, e.g., by factory calibration. For example, calibration measurements may be performed to measure the signal at various forward voltages as a function of the measured forward voltage for a number of different wavelengths or wavelength ranges. From the empirical data, one or more correction coefficients are derived, e.g., for each wavelength or wavelength range, that describe the correction as a function of forward voltage. For example, the correction coefficients may be derived by fitting a correction curve to the empirical data or by modeling the dependence of the signal on the forward voltage. Therefore, analytical, empirical, or semi-empirical models are typically used for the correction. Details are provided further below.

[0131] Therefore, in general, the correction, correction factor, or correction function k(λ, U F ) is S LS,model (λ,U F ) dependencies. For a particular phosphor LED, the analytical model may be determined through a factory calibration process or a field calibration process (e.g., under controlled environmental conditions such as a known temperature). Additionally or alternatively, a batch calibration may be performed, whereby a model, such as an analytical model, may be obtained from independent measurements from representative devices for a batch of phosphor LEDs. This method is also referred to as calibration to a "gold standard."

[0132] The calibration factor is determined by the voltage V ... F,Ref The spectrum may be corrected to correspond to a reference forward voltage, e.g., measured at a reference temperature. As described above, the Model S spectrum may be calculated from the calibration data, e.g., by fitting a reference curve to the experimental data with the measured forward voltage on the horizontal axis and the signal at a particular wavelength on the vertical axis. LS,model (λ,U F ) can be derived from this model. Correction coefficients or functions k(λ,U F ) can be derived:

number

[0133] Therefore, in subsequent measurements, the detector signal (e.g., for each wavelength) is adjusted by applying a correction factor or function k(λ, U F ), producing a detector signal that is largely independent of the actual temperature at various locations in the spectrometer apparatus and that is largely immune to temperature drift and the like.

[0134] The spectrometer device can also be equipped with two temperature sensors. Using these temperature sensors, the temperature of the spectrometer device can be measured between measurements, but not while the spectrometer measurement is in progress. However, some characteristics and performance of the spectrometer device may be affected by temperature changes. Most notably, the impedance of the detector (e.g., a PbS detector) decreases significantly with increasing temperature. This can introduce errors in the detected light intensity and reduce the reproducibility of spectrometer measurements under thermally different conditions, even when the actual lighting conditions remain unchanged. However, because the temperature of the spectrometer device cannot be tracked during the measurement, thermal drift that occurs during the measurement cannot be dynamically tracked or compensated for; the temperature during the measurement can only be roughly estimated from the temperature before and after the experiment. The present invention proposes a method to account for the fluctuations in the forward voltage due to temperature changes that occur during the LED's on-phase.

[0135] In particular, the correction according to the present invention may be further configured to take into account fluctuations in the positive voltage in the on-phase of the light source. As mentioned above, the at least one driving unit may also be configured to apply a modulation driving scheme for driving the light source. According to the modulation driving scheme, the light source may exhibit alternating on-phase and off-phase states. In particular, the LEDs are switched on and off sequentially. For example, the modulation driving scheme may include a pulse width modulation scheme using an essentially square wave signal with a fixed periodic duration, oscillating between two different positive voltage levels (in particular, oscillating between a minimum level and a maximum level). In this specification, the term "on-phase" is a broad term and is intended to have the meaning normally understood by those skilled in the art, and is not limited to any special or customized meaning. In particular, U F This includes, but is not limited to, a phase where the amount of an off-phase exceeds a minimum level. As used herein, the term "off-phase" is a broad term and is intended to have the general meaning commonly understood by those skilled in the art, and is not limited to any special or customized meaning. This term is used without limitation in the U F may represent phases at a minimum level, specifically phases that do not have a defined value.

[0136] As mentioned above, the drive unit 、 While driving the light source, a positive voltage U F and positive current I F It can also be configured to measure the forward voltage U F and positive current I F The measurement of 、 This can be done by measuring the current through a sense resistor, especially a shunt resistor, connected in series with the LED. F may be stably controlled to a certain level during the on-phase of the LED, while U F may vary depending on the actual temperature of the LED junction. This temperature dependence may typically show a linear relationship with a negative slope. For example,

number

[0137] T in the on phase pn (U F The function T may be predetermined, for example, by the manufacturer, or may be determined at the customer's site before performing the spectroscopic measurement. pn (U F ) function can be predetermined by performing the following steps:

[0138] - exposing the spectroscopic device to a plurality of different temperatures; - measuring temperature values ​​using at least one temperature sensor at each different temperature; - Maximum forward voltage U of the first on-phase at each temperature F measuring step; - Measured U F and temperature pairs to determine a function of the parameters α and U0.

number

number

[0139] For example, U F Several measurements of U may be taken. These different temperatures may be set externally, for example using a climate chamber or an electric heating element, to cover a wide range of temperatures, or may be controlled by small thermal changes caused by subsequent measurements. In each measurement, the temperature is measured with at least one temperature sensor and the maximum U during the first on-phase is F The first ON phase is expected to be the most consistent with the temperature measured by the temperature sensor before the measurement. Fand temperature), the parameter α and the function

number

number

[0140] In summary, and without excluding further possible embodiments, the following embodiments are contemplated: "Embodiment 1" 1. A spectroscopic device for obtaining spectral information about at least one object, comprising: i. at least one light source for generating illumination light for illuminating an object, the light source including at least one light emitting diode and at least one luminescent material for photoconversion of primary light generated by the light emitting diode; ii. at least one detector for detecting detection light detected from the object; iii. at least one driving unit for electrically driving the light source; iv. at least one measuring unit for generating at least one information relating to at least one electrically measurable quantity, in particular the forward voltage required to drive the light-emitting diode, in particular the voltage applied in the forward direction to the light-emitting diode to generate a predetermined current through the light-emitting diode; and iv. At least one electrically measurable quantity, in particular the forward voltage required to drive a light-emitting diode. v. at least one evaluation unit for evaluating at least one detector signal generated by the detector and for deriving spectral information of the object from the detector signal, the evaluation unit being configured to take into account information on at least one electrically measurable quantity, in particular a forward voltage, when deriving the spectral information from the detector signal; 1. A spectroscopic apparatus comprising:

[0141] "Embodiment 2" 2. The spectroscopic device of embodiment 1, wherein the light source comprises a phosphor light emitting diode.

[0142] "Embodiment 3" 3. The spectroscopic device of embodiment 1 or 2, wherein the dominant emission wavelength range of the light-emitting diode is at least partially located within the spectral range of 420 nm to 460 nm, more particularly within the range of 440 nm to 455 nm, and even more particularly at 440 nm.

[0143] "Embodiment 4" 4. The spectroscopic device according to any one of the first to third embodiments, wherein the illumination light has a spectral range at least partly located within the near-infrared spectral range, in particular in the range of 1 μm to 3 μm, preferably in the range of 1.3 μm to 2.5 μm, and more preferably in the range of 1.5 μm to 2.2 μm.

[0144] "Embodiment 5" A spectroscopic device according to any one of embodiments 1 to 4, wherein the evaluation unit is configured to determine at least one correction from information relating to at least one electrically measurable quantity, in particular the forward voltage, and in particular the correction is based on a model describing the spectral characteristics of the light source as a function of the at least one electrically measurable quantity, in particular the forward voltage, and the evaluation unit is further configured to correct at least one detector signal using said correction.

[0145] "Embodiment 6" 6. The spectroscopic device according to any one of embodiments 1 to 5, wherein the correction comprises multiplying at least one detector signal by at least one correction factor.

[0146] "Embodiment 7" 7. The spectroscopic device according to any one of embodiments 1 to 6, wherein the evaluation unit is configured to derive spectral information using the corrected detector signal.

[0147] "Embodiment 8" A spectroscopic device according to any one of embodiments 5 to 7, wherein the detector is configured to generate detector signals for at least two different spectral ranges of light obtained from the object, in particular configured to generate at least one sequentially or simultaneously, and the evaluation unit is configured to individually correct the detector signals for the different spectral ranges and derive spectral information by combining the individually corrected detector signals.

[0148] "Embodiment 9" A spectroscopic device according to any one of embodiments 5 to 8, wherein the detector comprises an array of light-sensitive elements, each light-sensitive element being configured to generate at least one detection signal, and the evaluation unit is configured to correct each detection signal individually and combine the detection signals to derive spectral information.

[0149] "Embodiment 10" 10. The spectroscopic device of embodiment 9, wherein the light-sensitive elements are configured to be sensitive to different spectral ranges of light from the object.

[0150] "Embodiment 11" 10. The spectroscopic device of embodiment 9, wherein the spectroscopic device includes at least one filter element disposed in the optical path of the light from the object, the filter element configured to expose each photosensitive element to a respective spectral range of the light from the object.

[0151] "Embodiment 12" The spectroscopic device according to any one of embodiments 1 to 11, further comprising at least one wavelength selection element, the wavelength selection element including at least one of a wavelength selection element arranged in the optical path of the illumination light and a wavelength selection element arranged in the optical path of the detection light.

[0152] "Embodiment 13" 13. The spectroscopic device of embodiment 12, wherein the wavelength-selective element is selected from the group of a tunable wavelength-selective element or a wavelength-selective element with a fixed transmission spectrum.

[0153] "Embodiment 14" 1. A method for obtaining spectral information of at least one object, the method comprising: a. electrically driving at least one light source using at least one driving unit, the light source including at least one light emitting diode and at least one luminescent material for photoconverting primary light generated by the light emitting diode; b. generating, using at least one measuring unit, at least one piece of information relating to at least one electrically measurable quantity, in particular the forward voltage required to drive the light-emitting diode; c. illuminating the object with illumination light generated by the light source; d. detecting the detection light from the object using at least one detector; and e. evaluating at least one detector signal generated by the detector using at least one evaluation unit and deriving spectral information of the object from the detector signal using the evaluation unit, wherein information on at least one electrically measurable quantity, in particular the forward voltage, is taken into account when deriving the spectral information from the detector signal; A method comprising:

[0154] "Embodiment 15" The method according to embodiment 14, using a spectroscopic device according to any one of embodiments 1 to 13 relating to the spectroscopic device.

[0155] "Embodiment 16" 16. The method according to method embodiment 14 or 15, wherein the method is performed online on-site.

[0156] "Embodiment 17" 17. The method according to any one of method embodiments 14 to 16, wherein in step e. at least one correction is determined from information about at least one electrically measurable quantity, in particular the forward voltage, and further wherein said correction is used to correct at least one detector signal.

[0157] "Embodiment 18" 18. The method of embodiment 17, wherein the correction is based on a model describing the spectral characteristics of the light source as a function of at least one electrically measurable quantity, in particular the forward voltage.

[0158] "Embodiment 19" 19. The method according to embodiment 17 or 18, wherein the correction comprises multiplying the at least one detection signal by at least one correction factor.

[0159] "Embodiment 20" 20. The method according to any one of embodiments 17 to 19, wherein the corrected detection signal is used to derive spectral information.

[0160] "Embodiment 21" A method according to any one of embodiments 17 to 20, wherein the detector generates detector signals for at least two different spectral ranges of light from the object, particularly generating at least one sequentially or simultaneously, and the method includes a step of individually correcting the detector signals in the different spectral ranges and deriving spectral information by combining the individually corrected detector signals.

[0161] "Embodiment 22" A method according to any one of embodiments 17 to 21, wherein the detector comprises an array of light-sensitive elements, each light-sensitive element configured to generate at least one detection signal, and the method comprises a step of individually correcting each detection signal and combining the detection signals to derive spectral information.

[0162] "Embodiment 23" 23. The method of embodiment 22, wherein the light-sensitive elements are configured to be sensitive to different spectral ranges of light emitted from the object.

[0163] "Embodiment 24" 24. The method of embodiment 23, wherein the spectroscopic device includes at least one filter element disposed in the optical path of the light from the object, the filter element configured to expose each photosensitive element to a respective spectral range of the light from the object.

[0164] "Embodiment 25" 25. The method according to any one of embodiments 14 to 24, wherein at least step e of the method is computer-implemented.

[0165] "Embodiment 26" A computer program, the instructions of which, when executed by an evaluation unit of a spectroscopic device referring to any one of embodiments 1 to 13 of any preceding paragraph relating to a spectroscopic device, are configured to cause the evaluation unit to perform a method referring to any one of embodiments 14 to 25 relating to a method. "Embodiment 27" A computer-readable storage medium, the computer-readable storage medium storing instructions that, when executed by an evaluation unit of a spectroscopic device according to any one of embodiments 1 to 13 of the preceding paragraph, cause the evaluation unit to perform the method according to any one of embodiments 14 to 26.

[0166] "Embodiment 28" A non-transitory computer-readable medium comprising instructions, which when executed by an evaluation unit of a spectroscopic device described in any one of embodiments 1 to 13 relating to a spectroscopic device, cause the evaluation unit to perform a method according to the method described in any one of embodiments 14 to 25. [Brief explanation of the drawings]

[0167] Furthermore, optional features and embodiments are disclosed in the detailed description of the embodiments, preferably in combination with the dependent claims. In this case, as will be understood by those skilled in the art, each optional feature can be realized independently or in any possible combination. The scope of the invention is not limited by the preferred embodiments. The embodiments are illustrated schematically in the drawings. In these drawings, the same reference numerals represent the same or functionally equivalent elements. [Figure 1] FIG. 1 shows a schematic diagram of the spectrometer setup. [Figure 2] FIG. 2 shows a schematic cross-sectional view of the light source. [Figure 3] FIG. 3 shows a schematic flow chart illustrating the generation and processing of detector signals. [Figure 4] FIG. 4 shows a diagram illustrating the overlay of infrared emission spectra of phosphor LEDs at various temperatures. [Figure 5] FIG. 5 shows a diagram illustrating the temperature-dependent light output variation at selected wavelengths. [Figure 6] FIG. 6 shows a plot of forward voltage versus temperature at selected currents. [Figure 7] 7A and 7B show the spectra of two different phosphor LEDs. [Figure 8] 8A and 8B show graphs illustrating the wavelength dependence of the decay constant (FIG. 8A) and growth constant (FIG. 8B) for a phosphor LED emitting in the wavelength range from 1.3 μm to 2 μm. [Figure 9]9A and 9B show the decay constant (FIG. 9A) and growth constant (FIG. 9B) as a function of wavelength for a phosphor LED emitting in the wavelength range of 1.6 μm to 2.1 μm. [Figure 10] FIG. 10 shows a plot of normalized light output as a function of normalized light output for positive current. [Figure 11] 11A and 11B show a plot of the raw detector signal for a particular detector pixel as a function of the forward voltage applied to the phosphor LED, along with a curve modeling this function (FIG. 12A) and the corrected detector signal as a function of the forward voltage applied to the phosphor LED (FIG. 12B). [Figure 12] 12A and 12B show the same views as FIGS. 11A and 12B, but for different detector pixels. [Figure 13] 13A and 13B show the same views as FIGS. 12A and 12B, but for different detector pixels. [Figure 14] FIG. 14 shows a schematic flow chart of a method for obtaining spectral information of at least one object. [Figure 15] FIG. 15 shows an example of the linear dependence of the forward voltage on the temperature measured by the temperature sensor. DETAILED DESCRIPTION OF THE INVENTION

[0168] FIG. 1 shows a schematic diagram of a spectroscopic device 110 for obtaining spectral information of at least one object 112. As shown in FIG. 1, the spectroscopic device 110 may include multiple components. The components of the spectroscopic device 110 and their interactions are described below with particular reference to FIG. 1. The spectroscopic device 110 includes at least one light source 114 that generates illumination light 116 for illuminating the object 112. The light source 114 may be, or may include, any of, a tunable light source, a light source having at least one fixed emission wavelength, or a broadband light source, or a combination thereof. The light source 114 may, in particular, be, or may include, at least one electric light source. The light source 114 includes a light-emitting diode 118 and at least one luminescent material 120 that photoconverts primary light generated by the light-emitting diode 118. For example, the light-emitting diode 118 may include any one or more of the following: a light-emitting diode (LED) based on spontaneous emission, a light-emitting diode based on superluminescence (sLED), or a laser diode (LLED).

[0169] The LED 118 may include at least two semiconductor material layers 121, configured such that light is generated by recombination of, in particular, positive and negative electrical charges at the interface between the at least two semiconductor material layers 121. The at least two semiconductor material layers 121 may have different electrical properties, for example, at least one layer being an n-type doped semiconductor material 121 and at least one layer being a p-type doped semiconductor material 121. Thus, for example, the LED 118 may include at least one pn junction and / or at least one pin arrangement, although other device structures are possible.

[0170] The light-emitting diode 118 generates primary light, also referred to as "pump light." The primary light may be converted into "secondary light," for example, by photoconversion via one or more luminescent materials 120 (e.g., phosphor materials). Thus, at least one luminescent material 120 may form at least one converter (also referred to as an optical converter) and convert the primary light into secondary light having spectral characteristics different from those of the primary light. In particular, the spectral width of the secondary light may be wider than that of the primary light, and / or the central wavelength of the secondary light may be shifted (e.g., red-shifted) relative to the primary light. In particular, the at least one luminescent material 120 may have absorption in the ultraviolet and / or blue spectral region and emission in the near-infrared and / or infrared spectral region. The illumination light 116 may be or include a mixture of the primary light or a portion thereof, the secondary light or a portion thereof, or both.

[0171] As shown in FIG. 1, light source 114 may specifically include a phosphor light-emitting diode 122 (hereinafter also referred to as phosphor LED 122). Phosphor LED 122 may be a combination of at least one light-emitting diode 118 configured to generate primary light or pump light and at least one luminescent material 120 (phosphor) configured to photoconvert the primary light generated by light-emitting diode 118. Phosphor LED 122 may form a packaged LED light source including an LED die 124, e.g., a blue LED, emitting blue pump light, and a phosphor, e.g., fully or partially covering LED 118, including LED 118 configured to convert the primary light or blue light to light with different spectral characteristics, e.g., near-infrared light. FIG. 2 shows a detailed perspective view of light source 114 implemented as a phosphor LED 122.

[0172] In general, the light source 114 can be implemented in a variety of forms. For example, as shown in Figure 1, the light source 114 can be configured as part of the spectroscopic device 110, disposed within a housing 126 of the spectroscopic device 110. Alternatively, or additionally, at least one light source 114 can be disposed outside the housing 126, e.g., as a separate light source 114 not shown. The light source 114 can be disposed at a location remote from the object 110 and illuminate the object 110 (see Figure 1).

[0173] Illumination light 116 generated by light source 114 may propagate from light source 114 to object 112. In Figure 1, the illumination light 116 generated by light source 114 and propagating to object 112 is indicated by an arrow. Object 112 may, among other things, include at least one sample that can be fully or partially analyzed by spectroscopy.

[0174] As can be seen in FIG. 1 , the spectroscopic device 110 further includes at least one detector 128 configured to detect detected light 130 emanating from the object 112. Light propagating from the light source 114 to the object 112 may be referred to as "illumination light 116," while light propagating from the object 112 to the detector 128 is labeled "detected light 130." In FIG. 1 , the detected light 130 is indicated by an arrow. The detected light 130 may include illumination light 116 reflected by the object 112, illumination light 116 scattered by the object 112, illumination light 116 transmitted by the object 112, luminescence light generated by the object 112, e.g., fluorescent light or fluorescence light generated by the object 112 after the object 112 is optically, electrically, or acoustically stimulated by the illumination light 116 or similar light. Thus, the detection light 130 may be generated directly or indirectly by illumination of the object 112 by the illumination light 116 .

[0175] The detector 128 may be or may include at least one optical detector 132. The optical detector 132 may also be configured to measure at least one optical parameter, such as the intensity and / or power of light irradiating at least one photosensitive area of ​​the detector 132. More particularly, the optical detector 132 may also include at least one light-sensitive element and / or at least one optical sensor, such as at least one of a photodiode, a photocell, a photosensitive resistor, a phototransistor, a thermophilic sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier, or a bolometer. The detector 128 may therefore be configured to generate at least one detection signal in the above sense, more particularly at least one electrical detection signal, which provides information about an optical parameter, such as the power and / or intensity of light irradiating the detector 128 or a photosensitive area of ​​the detector 128.

[0176] The detector 128 may include a single light-sensitive element or region, or multiple light-sensitive elements or regions. As shown in FIG. 1, the detector 130 may include at least one detector array, more particularly an array of light-sensitive elements 134. Each light-sensitive element 134 may be configured to generate at least one detector signal. In particular, each light-sensitive element 134 may include at least one light-sensitive region adapted to generate an electrical signal in response to the intensity of the incident light, which electrical signal may be provided to an evaluation unit 136 of the spectroscopic device, as described below.

[0177] If the detector 128 comprises an array of photosensitive elements 134, the detector 128 may, for example, be selected from known pixel sensors, and in particular may be selected from CCD or CMOS chips. Alternatively, the detector 128 may generally be or comprise a photoconductor, in particular an inorganic photoconductor (e.g., PbS, PbSe, Ge, InGaAs, InGaAs, InSb, or HgCdTe). As a further alternative, it may comprise at least one of pyroelectric, bolometer, or thermopile detector elements.

[0178] The spectroscopic device 110 includes at least one evaluation unit 136 that evaluates at least one detector signal generated by the detector 128 and derives spectral information of the object 112 from the detector signal. The detector 128 may provide the detector signal to the evaluation unit 136 directly or indirectly. Thus, the detector 128 and the evaluation unit 136 may be directly or indirectly connected, as shown by the arrows in FIG. 1 . The detector signal may be used as a “raw” detector signal and / or may be processed or pre-processed before further use, including, for example, by filtering. Thus, the detector 128 may also include at least one processing unit and / or at least one pre-processing unit (e.g., amplifier, analog-to-digital converter, electrical filter, Fourier transform, etc.).

[0179] As shown in FIG. 1 , the spectroscopic device 110 further comprises at least one driving unit 138 for electrically driving the light source 114. The spectroscopic device 110 includes at least one measurement unit 139. The measurement unit 139 is configured to generate at least one information regarding at least one electrically measurable quantity, in particular a forward voltage, required to drive the light-emitting diode 118. The measurement unit 139 may be an element of the driving unit 138, as shown in FIG. 1 . In particular, the driving unit 138 may be configured to supply an electrical current to the LED 118 and in particular to control the electrical current through the LED 118. For example, the driving unit 138 may be configured to adjust and measure the voltage supplied to the LED 118, which voltage is required to achieve a specific electrical current through the LED 118. The driving unit 138 may in particular include one or more of the following: a current source 140, a voltage source, a current measuring device (e.g., an ampere meter), a voltage measuring device 142 (e.g., a voltmeter), and a power measuring device. In particular, the driving unit 138 may include at least one current source 140 for providing at least one predetermined current to the LEDs 118, which may be configured to regulate or control a voltage applied to the LEDs 118 to generate the predetermined current. The driving unit 138 may also include one or more electrical components, such as, for example, an integrated circuit, for driving the light source 114. The driving unit 138 may be fully or partially integrated into the light source 114, or may be separate from the light source 114, the latter configuration being shown in FIG. 1 .

[0180] As mentioned above, the driving unit 138 is configured to generate at least one information regarding at least one electrically measurable quantity, in particular a forward voltage, required to drive the light-emitting diode 118. The forward voltage may be applied to the LED in a positive direction, i.e., such that the positive pole of the voltage or current source 140 is connected to the p-layer and the negative pole is connected to the n-layer of the LED 118, thereby causing a predetermined electrical current to flow through the LED 118. For example, the predetermined current defining the forward voltage is a current known to generate a predetermined light output of the light source 114 and / or the light-emitting diode 118.

[0181] The measurement unit 139 may also include one or more measuring devices or elements (e.g., one or more voltage measurement devices 142) to generate at least one information about at least one electrically measurable quantity (e.g., a forward voltage) necessary to drive the LED 118, e.g., to drive the LED 118 with a predetermined electrical current in the forward direction. The at least one information about the at least one electrically measurable quantity, e.g., the forward voltage, may be provided from the measurement unit 139 as at least one electrical signal and / or electrical information, e.g., including one or both of an analog signal and a digital signal. The electrical signal containing the at least one information about the at least one electrically measurable quantity, e.g., the forward voltage, may be provided directly or indirectly to the evaluation unit 136. The electrical signal may be time-dependent or static.

[0182] As mentioned above, as shown in FIG. 1 , the spectroscopic device 110 comprises at least one evaluation unit 136 for evaluating at least one detector signal generated by the detector 128 and deriving spectral information of the object 112 from the detector signal. The evaluation unit 136 is configured to take into account information related to at least one electrically measurable quantity, in particular the forward voltage, when deriving the spectral information from the detector signal. In particular, the evaluation unit 136 may also be configured to process at least one input signal and generate its at least one output signal. The at least one input signal may, for example, comprise at least one detector signal provided directly or indirectly from the at least one detector 128 and further at least one signal provided directly or indirectly from the measurement unit 139. This signal comprises at least one item of information related to the at least one electrically measurable quantity, in particular the forward voltage. The arrow between the drive unit 138, which in the embodiment shown in FIG. 1 comprises a measurement unit 139, and the evaluation unit 136 in FIG. 1 indicates the provision to the evaluation unit 136 of a signal comprising at least one item of information relating to at least one electrically measurable quantity and / or the acquisition of said signal by the evaluation unit 136.

[0183] The evaluation unit 136 may be or include one or more integrated circuits (e.g., one or more application-specific integrated circuits (ASICs)) and / or one or more data processing devices 144 (e.g., one or more computers, digital signal processors (DSPs), field programmable gate arrays (FPGAs)), preferably one or more microcomputers and / or microcontrollers. It may also include additional components, such as one or more preprocessing devices 146 and / or data acquisition devices (e.g., one or more devices for receiving and / or preprocessing detector signals, such as one or more analog-to-digital converters and / or one or more filters). Furthermore, the evaluation unit may also include one or more data storage devices 148, as shown in FIG. 1 . Furthermore, the evaluation unit 136 may also include one or more interfaces, such as one or more wireless interfaces and / or one or more wired interfaces.

[0184] In particular, the evaluation unit 136 can be configured, for example by software programming, to determine at least one correction from information related to the at least one electrically measurable quantity, in particular a correction based on a model describing the spectral characteristics of the light source 114 as a function of the at least one electrically measurable quantity, in particular the forward voltage. The evaluation unit 136 can also be further configured to correct the at least one detection signal using the correction. The correction can also include multiplying the at least one detection signal by at least one correction factor, as described in detail above and exemplarily further described below. The evaluation unit 136 can also be configured, in particular, to derive spectral information using the corrected detection signal.

[0185] As described in detail above, the detector 128 may specifically include an array of light-sensitive elements 134. Each light-sensitive element may be configured to generate at least one detection signal. The evaluation unit 136 may be configured to individually correct each detection signal and combine the detection signals to derive spectral information. The spectrometer device 110 may be configured such that the light-sensitive elements of the detector 128 are sensitive to different spectral ranges of light from the object 112. In particular, the detector 128 may be configured to generate detector signals corresponding to at least two different spectral ranges of light from the object 112 (particularly, sequentially or simultaneously). The spectrometer 110 may also be configured to include at least one filter element 150 disposed in the optical path of the light from the object 112. The filter element 150 may be configured such that each light-sensitive element is exposed to a respective spectral range of light from the object 112.

[0186] The spectroscopic device 110 may further include one or more optical elements 151 (e.g., one or more of at least one mirror, at least one lens, at least one aperture, and at least one wavelength-selecting element 152). Specifically, the one or more optical elements 151 may be arranged in at least one of the optical path of the illumination light 116 or the optical path of the detection light 130. The spectroscopic device 110 may, in particular, include at least one wavelength-selecting element 152. The wavelength-selecting element 152 may, in particular, be selected from the group of an adjustable wavelength-selecting element 152 and a wavelength-selecting element 152 with a fixed transmission spectrum. For example, when an adjustable wavelength-selecting element 152 is used, different wavelength ranges may be selected sequentially. On the other hand, when a wavelength-selecting element 152 with a fixed transmission spectrum is used, the selection of the wavelength range is fixed but may depend, for example, on the position of the detector. The wavelength-selective element 152 may be used to separate the incident light into a spectrum of constituent wavelength signals and measure the intensity of each wavelength signal using a detector (e.g., detector 128 of spectroscopic device 110). Detector 128 may include an array of light-sensitive elements 134. The at least one wavelength-selective element 152 may include, for example, at least one of a filter, a diffraction grating, or a prism. The wavelength-selective element 152 may specifically include at least one wavelength-selective element 152 disposed in the optical path of the illumination light 116 and a wavelength-selective element 152 disposed in the optical path of the detection light 130. FIG. 1 illustrates an embodiment of the spectroscopic device 110 in which one wavelength-selective element 152 is disposed in the optical path of the illumination light 116 and one wavelength-selective element 152 is disposed in the optical path of the detection light 130.

[0187] The spectroscopic device 110, schematically illustrated in FIG. 1 , is configured to acquire spectral information about at least one object 112. In particular, the spectroscopic device may be configured to acquire information about the at least one object and / or radiation emitted from the at least one object, i.e., information characterizing at least one optical property of the object, and more particularly, information characterizing at least one optical property of the object, e.g., information qualitatively or quantitatively characterizing at least one of transmission, absorption, reflection, or emission. For example, the at least one spectral information may include at least one intensity information, e.g., information about the intensity of light transmitted, absorbed, reflected, or emitted by the object, expressed as a function of one or more wavelength ranges, e.g., wavelength or wavelength subranges. Accordingly, the spectroscopic device 110 may be configured to acquire at least one spectrum or at least a portion of a spectrum of the detected light 130 propagating from the object 112 to the detector 128. The spectrum may describe a radiometric unit of measurement of spectral flux, e.g., expressed in watts per nanometer (W / nm), or in other units (e.g., as a function of wavelength of the detected light). Thus, the spectrum may describe the optical power of light in a particular wavelength band, e.g., within the near-infrared (NIR) spectral range. The spectrum may include one or more optical variables as a function of wavelength, e.g., power spectral density, an electrical signal derived from the optical measurement, etc. Examples of spectra are shown, e.g., in Figures 4, 7A, and 7B. The spectroscopic device 110 may be, in particular, a portable spectroscopic device 110, which may be used in the field. FIG. 2 shows a schematic cross-sectional view of a light source 114. The at least one light source 114 of the spectroscopic device 110 may be configured to generate or provide electromagnetic radiation in one or more of the infrared, visible, or ultraviolet spectral ranges. Because many properties related to the material or chemical composition of the object 112 are derived from the near-infrared spectral range, the light used in typical applications of the present invention is light in the infrared (IR) spectral range, and preferably light in the near-infrared (NIR) and / or mid-infrared (Mid-IR) spectral range, particularly light having wavelengths between 1 μm and 5 μm, preferably between 1 μm and 3 μm. The light source 114 includes at least one light-emitting diode 118 and at least one luminescent material 120 for photoconversion of primary light generated by the light-emitting diode 118. The LED 118 and luminescent material 120 may comprise a phosphor LED 122, as described above.

[0188] The phosphor LED 122 shown in FIG. 2 may also include one or more functional components. Specifically, the phosphor LED 122 may also include one or more substrates 154, particularly one or more electrically insulating substrates 154. In particular, the phosphor LED 122 may also include one or more ceramic substrates 156, as shown in FIG. 2. The substrate 154 (base material 154) may be configured to support at least one LED die 124 and at least one luminescent material 120. Furthermore, as shown in FIG. 2, at least one substrate 154 may support and / or include at least one contact pad 158 and / or at least one electrical connection component (e.g., at least one metal contact and / or at least one metal lead). The substrate 154 may also be configured to function as a heat sink. For example, due to limited efficiency in the conversion of electrical energy to light energy, the LED die 124 may generate heat, as may the luminescent material 120, for example, during the conversion process. The heat may be dissipated to a substrate 154, such as a ceramic substrate.

[0189] As shown in FIG. 2, the phosphor LED 122 can also include a light-emitting diode 118. The light-emitting diode 118 can be configured to convert an electrical current into primary light, such as blue primary light, using at least one LED chip and / or at least one LED die 124, as shown in FIG. 2. Specifically, a pn diode can be used. As an example, one or more LEDs 118 selected from indium gallium nitride (InGaN)-based LEDs 118, GaN-based LEDs 118, LEDs 118 based on InGaN / GaN alloys or combinations thereof, and / or other LEDs 118 can be used. Additionally or alternatively, a quantum well LED 118 can be used, such as one or more quantum well LEDs 118 based on indium gallium nitride (InGaN). Additionally or alternatively, a superluminescent LED (sLED) and / or a quantum cascade laser can be used. As further apparent from FIG. 2, the phosphor LED may also include at least one luminescent material 120 configured to photoconvert the primary light generated by the light emitting diode 118. Various types of conversion and / or luminescence are known and may be used in the context of the present invention. Specifically, the luminescent material 120 may include at least one of the following: cerium-doped YAG (YAG:Ce3 + , or Y3Al5O 12 :Ce 3+ ); rare earth doped sialon; copper and aluminum doped zinc sulfide (ZnS:Cu,Al).

[0190] Specifically, the luminescent material 120 may form at least one layer. In general, various alternatives for disposing the luminescent material 120 relative to the light-emitting diode 118 are possible, alone or in combination. First, the luminescent material 120 (e.g., at least one layer of the luminescent material 120, e.g., a phosphor) can be disposed directly on the light-emitting diode 118. This can be the case, for example, when no material is present between the LED 118 and the luminescent material 120, or when one or more transparent materials (e.g., one or more transparent materials transparent to the primary light) are present between the LED 118 and the luminescent material 120. For example, a coating of the luminescent material 120 can be disposed directly or indirectly on the LED 118 (not shown). Additionally or alternatively, the luminescent material 120 can form, for example, at least one converter body 160 (at least one converter disk), also referred to as a converter platelet. The converter body 160 may be disposed above the LED 118, for example, by adhesively securing the converter body 160 to the LED 118, as shown in FIG. 2 . Additionally or alternatively, the luminescent material 120 may be remotely disposed such that primary light emitted from the LED 118 passes through an intermediate optical path before reaching the luminescent material 120 (not shown). For example, the remotely disposed luminescent material may form the converter body 160 or a solid body such as a disk or converter disk. The intermediate optical path may also include one or more optical elements, including lenses, prisms, gratings, mirrors, apertures, or combinations thereof. Thus, specifically, an optical system having imaging properties may be disposed in the intermediate optical path between the LED 118 and the luminescent material 120, for example, to focus or converge the primary light onto the converter body 160.

[0191] In light source 114, particularly phosphor LED 122, at least one luminescent material 120 may be positioned relative to light emitting diode 118 to allow heat transfer from light emitting diode 118 to luminescent material 120. More specifically, luminescent material 120 may be positioned to allow heat transfer by thermal radiation and / or thermal conduction, more preferably by thermal conduction. Thus, for example, as shown in FIG. 2, luminescent material 120 may be positioned to be in thermal and / or physical contact with light emitting diode 118. This generally allows the temperature of luminescent material 120 to be coupled to the temperature of light emitting diode 118.

[0192] As shown in FIG. 2 , the light source 114, particularly the phosphor LED 122, may include additional components, such as at least one side coating 162 covering at least one side (e.g., top) and at least one side coating 162 covering the bottom and / or at least one side (e.g., at least one side of the substrate 154, contact pads 158, light-emitting diode 118, and luminescent material 120). Specifically, the side coating 162 may cover gaps and / or gaps that may exist in the layered structure of the light source 114, as shown in FIG. 2 . Other components of the light source 114, particularly components not shown in FIG. 2 , are possible. In general, the light source 114, particularly the phosphor LED 122, may be encapsulated in a housing not shown in FIG. 2 or may be constructed unencapsulated. Thus, the LED 118 and at least one luminescent material 120 for photoconverting the primary light generated by the LED 118 may be housed in a common housing. However, as shown in FIG. 2, the LED 118 may be a bare LED 118 without a housing.

[0193] The schematic flowchart of Figure 3 illustrates the process of generating a detection signal and processing the detection signal (e.g., generating a correction signal). Specifically, hardware components 164 that may participate in generating and / or pre-processing the detection signal and software components 166 that may participate in processing and / or correcting the detection signal are illustrated in Figure 3. The hardware components 164 (also simply referred to as "hardware" 164) include, among other things, at least one light-emitting diode 118 (particularly a blue LED 118) of the spectrometer device 110, configured to emit blue primary light. The hardware components 164 may further include a fluorescent material 120, also referred to as an LED phosphor, an object 112, and one or more optical components 151 (e.g., at least one wavelength-selecting element 152), as well as a detector 128.

[0194] As part of the corrections made by the evaluation unit 136, corrections may be made for temperature changes, including local temperature changes within the light source 114, which may affect the radiation characteristics of the light source 114. In FIG. 3, the temperatures of selected hardware components 164 are displayed in addition to the hardware components 164. The hardware components 164 may have different or the same temperatures depending on their location, e.g., relative position or distance, within the spectrometer apparatus 110. In particular, as mentioned above, the temperature of the luminescent material 120 and the temperature of the light emitting diode 118 may be coupled and influenced by heat transfer between the light emitting diode 118 and the luminescent material 120, either by thermal radiation or thermal conduction, or both. Thus, in particular, the temperature of the light emitting diode 118 (hereinafter "T pn ”) and the temperature of the luminescent material 120 (hereinafter referred to as “T Ph 3, the temperature of the LED 118 is indicated by reference numeral 168, the temperature of the luminescent material 120 is indicated by reference numeral 170, and the temperature of the detector 128 (T D (also referred to as the "internal interface") is designated by reference numeral 172.

[0195] The LED 118 may emit a primary light when an electrical current flows through the LED 118, for example, because the driving unit 138 applies an appropriate voltage to the LED to generate a particular electrical current (e.g., a predetermined electrical current). As shown in FIG. 3, for example, the driving unit 138 may receive a target signal S via reference numeral 174 to drive the LED 118 to emit a blue primary light. t may be provided. t 174 is a predetermined current value to be provided through the LED 118, which may be generated, for example, by applying an appropriate voltage. The predetermined current value may be in the range of 10 mA to 500 mA, more particularly in the range of 100 mA to 300 mA, for example, 50 mA. Thus, a predetermined current may be known to generate a predetermined light output (e.g., a predominantly blue light) of the LED 118. The LED 118 is maintained at a temperature "T" indicated by reference numeral 168. pn The blue primary light may be converted by the luminescent material 120 into secondary light (e.g., light in the infrared spectral range). The luminescent material 120 may be at a temperature "T ph ". The illumination light 116 generated by the light source 114 may include primary light or a portion thereof, secondary light or a portion thereof, or a mixture thereof, and may illuminate the object 112. One or more optical components 151 (e.g., one or more mirrors, lenses, wavelength-selective elements 152, or other optical components 151) may be used to direct the illumination light 116, for example, by placing the optical components 151 in the optical path of the illumination light 116. The detected light (e.g., reflected light) from the object 112 may be directed to the detector 128. Optionally, one or more optical elements 151 may also be used in the optical path of the detected light 130. For example, one or more wavelength-selective elements 152 (e.g., dispersive elements) may be used to split the detected light 130 into its spectral components.

[0196] As described in detail above, the detector 128 may include, for example, an array of light-sensitive elements 134. In particular, the detector 128 may be or include a pixel sensor, such as a CCD chip or a CMOS chip, with a plurality of pixels arranged on the chip. For example, each pixel may be configured to correspond to, e.g., be sensitive to, a predetermined spectral range. This allows the detector 128 to generate a detector signal S 1 including a plurality of detector signals, as shown at 176 in FIG. 3 . px,i 176. Thus, each of the plurality of detector signals may correspond to an electronic signal generated by each of the plurality of pixels of the detector 128. Each detector signal may be given, for example, as a numerical value corresponding to the number of counts of that pixel measured during a predetermined time interval. Thus, the detector signal S px,i 176 is indicated by the index "px" as a function that depends on the wavelength of the detected light 130. px,i 176 may also be a function of time, as indicated by the index "i", such as in the case of a time-dependent detector signal.

[0197] Detector signal S px,i The signals included in 176 may be generated simultaneously or in a time-sequential manner. px,i 176 can be determined using readout electronics 178 as shown in FIG. px,i 176 may be processed, for example, as part of pre-processing or as part of a further processing step. For example, the pixels included in detector 128 may generate an electronic detection signal S px,i 176, which may be an active pixel sensor adapted to amplify the signal, for example, as part of a pre-processing process performed as a precursor to further processing performed by one or more of the software components 166.

[0198] The signal S generated by the detector 128 px,i 176 also refers to the "frame signal S px,i176”. As shown in FIG. 3, the signal S px,i 176 to one of the software components 166. Specifically, the detector signal S px,i A software component 166 configured to process and / or correct 176 is 、 The system may also include at least one first software 180 (hereinafter also referred to as "Software 1") and at least one second software 182 (hereinafter also referred to as "Software 2"). The first software 180 is configured to generate a detector signal S px,i 176, which may be configured to perform at least one first processing step 184 (hereinafter also referred to as "Process 1") on the detector signal S px,i 176. The first processing step 184 may be realized by applying at least one algorithm to the detected signal S. In particular, the first processing step 184 may include correction of at least one transient or time-dependent effect. Thus, for example, the first processing step 184 may include one or more of the following: correction of the dark signal; correction of the dark signal drift; correction of fluctuation effects; correction of the photodetector response at individual detection elements or at individual time steps; correction of changes in the photodetector response due to environmental factors (e.g., temperature); extraction of information for subsequent processing; addition or multiplication with a parameter generated from information about at least one electrically measurable quantity (particularly the forward voltage) or device temperature. The first software 180 may also be configured to perform at least one additional step on the detected signal S, including at least one fast Fourier transform 186. Thus, the detected signal S px,i 176 is subjected to a first processing step 184 and / or a fast Fourier transform 186 to obtain a signal S px 188 (the so-called "pixel signal S px 188") can be generated. Specifically, a frame signal S px,i The time dependence of 176 is removed by one or more steps constituting the first software component 1, while the wavelength dependence is removed by one or more steps constituting the first software component 1, as indicated by the index "pn". 、 signal Spx 3, as indicated by the arrow, the signal S px 188 to the second software 182. The second software 182 receives the signal S px 188 may be configured to perform at least one second processing step 190 (so-called "Process 2") on the signal S px 188 by applying at least one algorithm to the at least one correction signal S px, corr 191. In particular, the second processing step 190 can include one or more of the following: correction of the dark signal signal; correction of the drift of the dark signal signal; correction of fluctuation effects; correction of the photodetector response at individual detection elements or individual time steps; correction of changes in the photodetector response due to environmental factors (e.g., temperature); extraction of information for subsequent processing; manipulation (e.g., addition or multiplication) with at least one parameter (e.g., a parameter generated from information about at least one electrically measurable quantity, in particular the forward voltage or the device temperature). In particular, the corrected signal S px, corr 191 may also include a plurality of corrected signals (e.g., a plurality of corrected electronic signals), each of which may specifically correspond to a corrected count number for a corresponding pixel.

[0199] The spectroscopic device 110 comprises at least one evaluation unit 136 for evaluating at least one detector signal generated by the detector 128 and deriving spectral information of the object 112 from the detector signal. The evaluation unit 136 is configured to take into account information about at least one electrically measurable quantity, in particular the forward voltage, when deriving the spectral information from the detector signal. The evaluation unit 136 may also be configured by software programming to evaluate and / or process the detector signal, in particular as part of a first processing step 184 of at least one first software 180. The evaluation unit 136 may in particular be configured to determine at least one correction from the information item about the at least one electrically measurable quantity, in particular the forward voltage, and may further be configured to correct the at least one detector signal using said correction. Thus, the evaluation unit 136 may determine at least one correction from the information item about the at least one electrically measurable quantity, in particular the forward voltage, and may also be configured to correct the at least one detector signal using said correction. px 188 processed and corrected 、 signal S px , i, corr , which may be further processed, for example by applying a fast Fourier transform 186.

[0200] The light-emitting diode 118 and the luminescent material 120 may be constructed from different materials and / or different compositions of materials, and generally, these constructions may affect the spectrum 192 of the phosphor LED 122, for example, as described in detail above. However, the spectrum 192 or its spectral characteristics of a particular phosphor LED 122 may change with temperature, even when operated at a particular preset current. These changes may include a shift in the emission peak 193, a broadening or narrowing of the spectrum 192, an increase or decrease in the amount of light emitted, etc. However, in many cases, the emission at certain wavelengths may be affected more than the emission at other wavelengths. This effect is illustrated in the diagram shown in FIG. 4, which shows an overlay of the infrared emission spectrum 192 of the phosphor LED 122 at various temperatures. Specifically, the diagram in FIG. 4 plots wavelength 198 in nanometers on the x-axis 200 and power spectral density (PDS) 194 in microwatts per nanometer (μW / nm) on the y-axis 196. In the illustrated spectrum 192, the temperature of the phosphor LED 122 generating the illumination light 116 ranges from 25°C to 50°C. Typically, there is a specific center wavelength within spectrum 192 that is independent of temperature changes. Therefore, each wavelength has its own temperature coefficient for increasing or decreasing output power. Therefore, as is evident from FIG. 4, the shape of spectrum 192 changes with temperature. To more clearly visualize this effect, four specific wavelength ranges across spectrum 192 are shown in FIG. 4, each centered around one of the four specific wavelengths. The wavelength ranges are delimited by dashed lines. Specifically, the following four wavelengths and their corresponding intervals are marked with the following reference symbols: 1643 nm, reference symbol 202; 1750 nm, reference symbol 204; 1802 nm, reference symbol 206; and 1950 nm, reference symbol 208. For each of these wavelengths, the normalized change in luminous power relative to the change in luminous power at 25°C is shown as a function of temperature in the temperature range from 25°C to 50°C in the diagram of FIG.In the diagram of Figure 5, the change in luminous power expressed as a percentage relative to the change in luminous power at 25°C is shown on the y-axis 196 at reference numeral 219, and temperature (°C) is shown on the x-axis 200 at reference numeral 220. The line in the diagram of Figure 5 represents a fitted curve 236. As is evident from Figure 5, the luminous output at the central wavelength of 1802 nm changes very little within the observed temperature range (i.e., the change in luminous output is zero or close to zero), while the change in luminous output at other wavelengths (e.g., 1643 nm and 1953 nm) can be significantly different.

[0201] For a particular current through the light-emitting diode 118 (e.g., a particular, predefined value of electrical current obtained by applying a forward voltage to the light-emitting diode 118), the appropriate forward voltage may be a function of the temperature of the light-emitting diode 118. Thus, for the same current applied to the light-emitting diode 118, the forward voltage of the light-emitting diode 118 typically decreases as the temperature increases. Each type of light-emitting diode 118 has its own characteristic curve of forward voltage versus temperature. Typically, the forward voltage of the light-emitting diode 118 decreases linearly with increasing temperature, e.g., 1·10 -4 ~1·10 -3 The temperature of the LED 118 varies with a slope in the range of V / K. Figure 6 illustrates this relationship for a particular LED 118. In particular, the diagram in Figure 6 plots the temperature of the LED 118 on the horizontal axis and the forward voltage applied to the LED 118 on the vertical axis when a DC current of 150 mA is applied to the LED 118. The forward voltage (in volts) is represented by reference character 224 on the y-axis 196. The temperature (in degrees Celsius) is represented by reference character 220 on the x-axis 200. As can be seen from Figure 6, in this case the forward voltage decreases linearly with increasing temperature. The curve in Figure 5 can be expressed by the following equation:

number

[0202] where U fwhere t denotes the forward voltage and T denotes the temperature. The illustration in Figure 6 shows measurement points 221 represented by grey filled circles and a dashed line corresponding to the fitted curve 236 given above. Instead of the equation or curve relating forward voltage to temperature exemplarily described above, the relationship between temperature and another electrically measurable quantity required to drive the light source can also be used, such as input power, current, resistance, inductance, capacitance, etc.

[0203] In this way, it is also possible to carry out individual temperature corrections of the spectrum 192 at different wavelengths by using at least one electrically measurable quantity, in particular the forward voltage, as a correction parameter. 、 Detection signal S px,i The optical fiber 130 may also be configured to individually correct a plurality of detected signals and combine the individually corrected detected signals to derive spectral information. As mentioned above, the individual correction may be performed using a photosensitive element array 134, where each photosensitive element is configured to generate at least one detected signal, and each detected signal is individually corrected using at least one electrically measurable quantity, in particular the forward voltage, as a correction parameter. Finally, the corrected detected signals may be combined to derive spectral information.

[0204] To derive spectral information, in particular the spectrum, of the object 112, the spectroscopic device 110, and in particular the evaluation unit 136, may also take into account in particular the properties of the luminescent material 120 used in the light source 114. As explained in detail above, the luminescent material 120 may be configured to absorb primary photons generated by the light emitting diode 118 and may emit secondary photons in response, either immediately or after a delayed or decay time. The signal or emission after switching off the forward current of the light emitting diode 122 (LED 122) can be described using equations (1) and (2) explained above.

[0205] Therefore, a particularly characteristic property of the luminescent material 120 is the decay constant τd 228 and the growth constant τ, which represents the typical time until the converted light emission reaches saturation. g The time constant τ d and τ g is typically different between different phosphor LEDs 122 and / or different types of phosphor materials 120. Furthermore, the decay constant τ d and the growth constant τ g may depend on wavelength. These time constants are usually extracted from the step response of the optical signal due to the application / cutoff of a forward current. Figures 7A and 7B show spectra 192 of two different phosphor LEDs 122 emitting light in the near-infrared region. Specifically, the power spectral density is given as a function of wavelength in nm. As is clear from Figures 7A and 7B, the spectra 192 of the two different phosphor LEDs 122 are different. For example, the spectrum 192 shown in Figure 7A shows high emission in the wavelength range from 1400 nm to 1600 nm, while the phosphor LED 122 having the spectrum 192 shown in Figure 7B has negligible emission in this region. The decay constant τ of the phosphor LED 122 having the spectrum shown in Figure 7A is d and the growth constant τ g are shown as a function of wavelength in Figures 8A and 8B, respectively. The decay constant τ of the phosphor LED 122 having the spectrum shown in Figure 7B d and the growth constant τ g is shown as a function of wavelength in Figures 9A and 9B, respectively. Specifically, Figures 8A and 9A each show the attenuation constant τ d 8B and 9B show the growth constant τ g The wavelength (in ms) is indicated by reference symbol 230 and is plotted on the y-axis 196 with wavelength (in nm) 198 on the x-axis 200. Data points for different replicate measurements are marked with different shades of grey.

[0206] Another characteristic of an LED 118 is its relationship to light output power as a function of forward current. Thus, generally, increasing the forward current (specifically, the input current) increases the power emitted by the LED 118. The curve (e.g., slope) of light output as a function of forward voltage is a characteristic unique to each individual LED 118. FIG. 10 shows an example of such a curve. Specifically, in the illustration of FIG. 10, the normalized light output 232 of a phosphor LED is shown as a function of forward current (forward current) 234 in amperes.

[0207] As described above, the evaluation unit 136 may be particularly configured to determine at least one correction from information about at least one electrically measurable quantity, particularly the forward voltage, and the correction may be based on a model that describes the optical spectral characteristics of the light source 114 as a function of the at least one electrically measurable quantity, particularly the forward voltage. The evaluation unit 136 may also be configured to correct at least one detector signal using the at least one correction, and may particularly include a configuration that multiplies the at least one detector signal by at least one correction factor. Figures 11A, 12A, and 13A each show the raw detector signal of a particular detector pixel as a function of the forward voltage applied to the phosphor-LED 122, along with a fitted curve 236 that models this function. Each different pixel may correspond to a different wavelength, as described in detail above. Specifically, in each of FIGS. 11A, 12A, and 13A, the signal in counts 226 on the y-axis 196 is shown as a function of the forward voltage (volts) 224 applied to the phosphor LED 122, represented on the x-axis 200. In the experimental data shown in FIGS. 11A, 12A, and 13A, a white target was used as the object 112 and was illuminated with the illumination light 116. At higher temperatures, a lower forward voltage is required to achieve a predefined current through the LED 118, and thus a lower forward voltage corresponds to a higher temperature (and vice versa). As is evident from a comparison of FIGS. 11A, 12A, and 13A, temperature dependence can vary significantly from pixel to pixel. Thus, specifically, the temperature dependence of the pixel shown in FIG. 13A is very low, meaning that a decrease in temperature or an increase in forward voltage results in little or no change in the detected signal for this pixel. On the other hand, the pixels shown in Figures 11A and 12A both exhibit a significant temperature dependence, with signal counts increasing sharply as the temperature decreases or the positive voltage increases.

[0208] The spectroscopic device 110, in particular the evaluation unit 136, can also be configured to perform a correction of the detector signal and generate a corrected emission spectrum, which is largely independent of the actual temperature at various locations of the spectroscopic device 110 and is further largely unaffected by temperature drift and similar factors. The theory and principles underlying the theoretical description of the emission spectrum of the light source 114 have been explained in detail above. In particular, reference is made to equations (3) to (8). Thus, as explained in detail above, the influence of temperature can be efficiently corrected by measuring at least one electrically measurable quantity, in particular the forward voltage for the reference measurement or the sample measurement, or during one measurement. In particular, the correction factor as described in equation (7) or the correction function k(λ,U) as described in equation (8) can be used to calculate the temperature effect. F ) can also be used to determine the corrected spectrum. Figures 11B, 12B, and 13B show the raw detected signal shown in Figures 11A, 12A, and 13A, with the correction coefficients or correction functions k(λ,U) shown in Figures 11B, 12B, and 13B, respectively. F 1 shows an example of a corrected detection signal determined by applying

[0209] 11B, 12B, and 13B are graphs each showing the forward voltage applied to the phosphor LED 122 on the horizontal axis and the corrected detector signal counts on the vertical axis. The corrected detector signal in counts shown on the y-axis 196 is marked with reference numeral 238, and has been subjected to a correction applied to the raw signal 226 as shown in FIGS. 11A, 12A, and 13A, respectively. As mentioned above, the evaluation unit 136 may be configured to individually correct the detector signals in different spectral ranges and to derive spectral information by combining the individually corrected detector signals. The correction of the emission spectrum may involve, for example, applying at least one reference forward voltage U as described in detail above. F,Ref11B, 12B, and 13B, in this example, the emission spectrum is corrected to a reference forward voltage corresponding to room temperature (e.g., 25°C). Additionally, other reference temperatures are possible, such as the housing temperature, the heat sink temperature, or other temperatures specific to the system. In particular, by selecting a reference temperature that corresponds to (e.g., is close to) the temperature within the spectroscopic device, the correction to the emission spectrum can be kept small.

[0210] Therefore, the detector signal (e.g., for each wavelength) is adjusted by applying a correction factor or function k(λ, U F ), which may produce a detector signal that is broadly independent of the actual temperature at various locations in the spectroscopic device 110, and is also less susceptible to temperature drift, etc., as shown in Figures 11B, 12B, and 13B.

[0211] In a further aspect, a method for obtaining spectral information of at least one object 112 is disclosed. The method includes performing the following steps in a predetermined order, although different orders are possible. In particular, one, more, or all of the method steps may be performed once or repeatedly. Furthermore, the method steps may be performed sequentially, or alternatively, one or more method steps may be performed in a timed overlapping, parallel, or combined manner. The method may include additional method steps not listed.

[0212] The method includes the following steps: a. electrically driving at least one light source 114 using at least one driving unit 138, the light source 114 including at least one light emitting diode 118 and at least one luminescent material 120 for photoconversion of primary light generated by the light emitting diode 118; b. generating, using at least one measuring unit 139, at least one piece of information relating to at least one electrically measurable quantity, in particular the forward voltage required to drive the light emitting diode 118; c. illuminating the object 112 with illumination light 116 generated by the light source 114; d. detecting the detected light 130 from the object 112 using the detector 128; and e. Evaluating at least one detector signal 248 generated by the detector 128 using at least one evaluation unit 136 and deriving spectral information of the object 112 from the detector signal, wherein information about at least one electrically measurable quantity, in particular information about the positive voltage, is taken into account when deriving the spectral information from the detector signal.

[0213] 14 shows a schematic flowchart of a method for obtaining spectral information of at least one object 112. In the flowchart, method step a. is designated by reference numeral 240, method step b. is designated by reference numeral 241, method step c. is designated by reference numeral 242, method step d. is designated by reference numeral 244, and method step e. is designated by reference numeral 246. Step e. includes evaluating a detector signal 248 and considering information about at least one electrically measurable quantity, in particular, forward voltage, when deriving spectral information from the detector signal 248. The flowchart illustrates, by an arrow from step d to step e, the process of providing at least one detector signal 248 generated by the detector 128 for evaluation in step e. Furthermore, an arrow from step b to step e illustrates the process of providing information about at least one electrically measurable quantity, in particular, forward voltage, that is considered in step e. A specific implementation of the method may be performed using a spectroscopic device 110 according to the present invention, for example, according to any one of the embodiments described above or any one of the embodiments described in more detail below. Therefore, for details of the method, such as details regarding terms, definitions, or examples, reference may be made to the description of the spectroscopic device 110 described above or the description described in more detail below.

[0214] The method can in particular be performed online, for example in the field. The spectroscopic device 110 is in particular a portable spectroscopic device 110, and can in particular be used in the field.

[0215] As outlined above, in step e., at least one correction may be determined from information about the forward voltage. Furthermore, at least one detector signal may be corrected using the correction. The correction may be determined based on a model describing the spectral characteristics of the light source 114 as a function of at least one electrically measurable quantity (particularly the forward voltage). Specifically, the correction may include multiplying at least one detector signal by at least one correction factor. The corrected detector signal may be used to derive spectral information. The detector 128 may generate detector signals for at least one spectral range of light from the object 112, particularly at least two different spectral ranges. The spectral ranges of the detector 128 may overlap or may not intersect with each other. The detector 128 may generate detector signals corresponding to at least two different spectral ranges of light from the object 112, sequentially or simultaneously. The method, particularly step e., may include separately correcting the detector signals for the different spectral ranges and combining the separately corrected detector signals to derive the spectral information.

[0216] The detector 128 may particularly include an array of light-sensitive elements 134. Each light-sensitive element may be configured to generate at least one detector signal. The method, particularly step e., may include correcting each detector signal individually and combining the detector signals to derive spectral information. The light-sensitive elements may particularly be sensitive to different spectral ranges of light from the object 112.

[0217] The spectroscopic device 110 may also specifically include at least one filter element 150 disposed in the optical path of the light from the object 112. The filter elements 150 may be configured such that each light sensitive element is exposed to a respective spectral range of the light from the object 112.

[0218] This method may be fully or partly computer-implemented, and thus step e. of the method may be computer-implemented.

[0219] The spectroscopic device 110 can also be equipped with two temperature sensors. Using these temperature sensors, the temperature of the spectroscopic device 110 can be measured between measurements, but not while the spectroscopic measurement is in progress. However, some characteristics and performance of the spectroscopic device 110 can be affected by temperature changes. Most notably, the impedance of the detector 128 (e.g., a PbS detector) decreases significantly with increasing temperature. This can introduce errors in the detected light intensity and reduce the reproducibility of spectroscopic measurements under thermally different conditions, even when the actual lighting conditions remain unchanged. However, because the temperature of the spectroscopic device 110 cannot be tracked during measurement, thermal drift that occurs during measurement cannot be dynamically tracked or compensated for; the temperature during measurement can only be roughly estimated from the temperature before and after the experiment. The present invention proposes a method to account for temperature changes that cause fluctuations in the forward voltage that occur during the LED's on-phase.

[0220] In particular, the correction according to the present invention may further be configured to take into account fluctuations in the positive voltage during the on-phase of the light source 114. As mentioned above, the at least one driving unit 138 may also be configured to apply a modulation driving scheme for driving the light source 114. According to the modulation driving scheme, the light source 114 may exhibit alternating on-phase and off-phase states. In particular, the LEDs 118 are switched on and off sequentially. For example, the modulation driving scheme may include a pulse width modulation scheme using an essentially square wave signal with a fixed periodic duration, oscillating between two different positive voltage levels (in particular between a minimum level and a maximum level). The on-phase may be U F The OFF phase is the phase where U exceeds the minimum level. F is at a minimum level, specifically a phase that does not have a defined value.

[0221] As described above, the driving unit 114 applies a forward voltage U F and the positive current I F The positive voltage U F and the positive current I F The measurement of 、 This can also be implemented by measuring the current through a sense resistor, particularly a shunt resistor, connected in series with the LED 118. f may be stably controlled to a constant level during the on-phase of the LED 118. F can vary depending on the actual temperature of the LED junction. This temperature dependence can usually be a linear relationship with a negative slope. For example,

number

[0222] Figure 15 shows an example of the linear dependence of the forward voltage on temperature as measured by a temperature sensor (e.g., one of the Centipede temperature sensors used). Figure 15 shows the relationship between U(F) / V as a function of temperature "xtm[0]" / °C.

[0223] T in the on phase pn (U F ) function may be predetermined, for example, by the manufacturer, or may be determined before performing the spectroscopic measurement at the customer's site. pn (U F ) function may be predetermined by performing the following steps: - exposing the spectroscopic device 110 to a plurality of different temperatures; - measuring temperature values ​​using at least one temperature sensor at each different temperature; - Maximum forward voltage U in the first on-phase at different temperatures F measuring step; - Measured U F and temperature pairs, the function

number

number

[0224] For example, U at different temperatures F It is also possible to carry out several measurements of U. These different temperatures can be set externally, for example using a climate chamber or an electric heating element, and can cover a wide range of temperatures or can be controlled by small thermal changes caused by subsequent measurements. In each measurement, the temperature is measured with at least one temperature sensor and the maximum U in the first ON phase is F The first ON phase is expected to be the most consistent with the temperature measured by the temperature sensor before the measurement. F and temperature) to obtain the function

number

number

[0225] 110 Spectrometer equipment 112 Object 114 Light source 116 Illumination 118 Light Emitting Diode 120 Luminescent Materials 121 Semiconductor Materials 122 Phosphor light-emitting diode 124 LED dies 126 Housing 128 detectors 130 Detected Light 132 Optical Detector 134 Array of light-sensitive elements 136 evaluation units 138 Drive Unit 139 Measuring Unit 140 Current source 142 Voltage measuring device 144 Data Processing Device 146 Pretreatment equipment 148 Data Storage Devices 150 filter elements 151 Optical Components 152 Wavelength selection element 154 Substrate (base material) 156 Ceramic Substrate 158 contact pads 160 Converter Body 162 Side Coat (Side Coating) 164 Hardware Components 166 Software Components 168 LED Temperature 170 Temperature of the luminescent material 172 Detector temperature 174 Target signal S t 176 Electronic detector signal S px,i 178 Readout Electronics 180 Software 1 182 Software 2 184 First Processing Step 186 Fast Fourier Transform 188 pixel signal S px 190 Second Processing Step 191 Signal S px, corr 192 Spectrum 193 Peak 194 microwatts per nanometer power spectral density 196 y-axis 198 wavelengths (nanometers) 200 x axis 202 1643nm 204 1750nm 206 1802nm 208 1950nm 219 Change in luminous output normalized to 25°C (expressed as a percentage) 220 Temperature (℃) 221 measurement points 224 Forward voltage (V) 226 Signal Counts 228 Attenuation constant τ d (milliseconds) 230 Growth constant (τ g ) Unit: ms 232 Standardized (normalized) light output 234 Forward Current (Amperes) 236 Fitting curve 238 Corrected detector signal (counts) 240 Method Step a. 241 Method Step b. 242 Method Step c. 244 Method Step d. 246 Method Step e. 248 detector signal 250 Information items relating to electrically measurable quantities

Claims

1. A spectroscopic device (110) for obtaining spectral information of at least one object (112), comprising: i. at least one light source (114) for generating illumination light (116) for illuminating an object (112), the at least one light source (114) including at least one light emitting diode (118) and at least one luminescent material (120) for photoconverting primary light generated by the light emitting diode (118); ii. at least one detector (128) for detecting the detection light (130) from the object (112); iii. at least one driving unit (138) for electrically driving the light source (114); iv. at least one measuring unit (139) for generating at least one piece of information relating to at least one electrically measurable quantity, in particular the forward voltage required to drive the light-emitting diode (118); and v. at least one evaluation unit (136) for evaluating at least one detector signal generated by the detector (128) and deriving spectral information of the object (112) from the detector signal, the evaluation unit (136) being configured to take into account information about at least one electrically measurable quantity, in particular a positive voltage, when deriving the spectral information from the detector signal; a spectroscopic device (110) comprising:

2. The spectroscopic device (110) of claim 1, wherein the light source (114) comprises a phosphor light emitting diode (122).

3. 3. The spectroscopic device (110) of claim 1 or 2, wherein the light emitting diode (118) has a dominant emission wavelength range that is at least partially located within a wavelength range of 420 nm to 460 nm.

4. 3. The spectroscopic device (110) of claim 1 or 2, wherein the illumination light (116) has a spectral range that is at least partially located within the near-infrared spectral range.

5. 3. The spectroscopic device (110) of claim 1 or 2, wherein the evaluation unit (136) is configured to determine at least one correction from information about at least one electrically measurable quantity, in particular information about the forward voltage, and further wherein the evaluation unit (136) is configured to correct at least one detection signal using the correction.

6. 6. The spectroscopic device (110) of claim 5, wherein the correction comprises multiplying at least one detected signal by at least one correction factor.

7. 6. The spectroscopic device (110) of claim 5, wherein the evaluation unit (136) is configured to derive spectral information using the corrected detection signal.

8. 6. The spectrometer device (110) of claim 5, wherein the detector (128) is configured to generate detector signals corresponding to at least two different spectral ranges of light from the object (112), and the evaluation unit (136) is configured to individually correct the detector signals for the different spectral ranges and to derive spectral information by combining the individually corrected detector signals.

9. 6. The spectroscopic device (110) of claim 5, wherein the detector (128) comprises an array of light-sensitive elements (134), each light-sensitive element configured to generate at least one detection signal, and the evaluation unit (136) is configured to correct each detection signal individually and combine the detection signals to derive spectral information.

10. A method for obtaining spectral information of at least one object (112), the method comprising: a. electrically driving at least one light source (114) using at least one driving unit (138), the light source (114) including at least one light emitting diode (118) and at least one luminescent material (120) for photoconversion of primary light generated by the light emitting diode (118); b. generating, using at least one measuring unit (139), at least one piece of information relating to at least one electrically measurable quantity, in particular the forward voltage, required to drive the light-emitting diode (118); c. illuminating the object (112) with illumination light (116) generated by a light source (114); d. detecting the detected light (130) from the object (112) using at least one detector (128); and e. evaluating at least one detector signal generated by the detector (128) using at least one evaluation unit (136) and deriving spectral information of the object (112) from said detector signal using the evaluation unit (136), wherein information about at least one electrically measurable quantity, in particular the forward voltage, is taken into account when deriving the spectral information from the detector signal; A method comprising:

11. 11. The method according to claim 10, wherein in step e) at least one correction is determined from information about at least one electrically measurable quantity, in particular the forward voltage, and further wherein said correction is used to correct at least one detector signal.

12. 12. The method of claim 11, wherein the detector comprises an array of light-sensitive elements (134), each light-sensitive element configured to generate at least one detector signal, and the method comprises the steps of individually correcting each detector signal and combining the detector signals to derive the spectral information.

13. 12. A computer program comprising instructions, the instructions of the program being configured, when executed by an evaluation unit (136) of a spectroscopic device (110) according to claim 1 or 2, to cause the evaluation unit (136) to perform the method according to claim 10 or 11.

14. 12. A computer-readable storage medium comprising instructions, which when executed by an evaluation unit (136) of a spectroscopic device (110) according to claim 1 or 2 relating to a spectroscopic device (110), cause the evaluation unit (136) to perform the method according to claim 10 or 11 relating to the method.

15. A non-transitory computer readable medium comprising instructions which, when executed by an evaluation unit (136) of a spectroscopic device (110) according to claim 1 or 2 relating to a spectroscopic device (110), cause the evaluation unit (136) to perform the method according to claim 10 or 11 relating to a method.

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