In-situ wavelength calibration of wavelength scales of spectrometer devices

Abstract

A spectrometer device (110) for obtaining spectroscopy information about at least one object (112), the spectrometer device (110) comprising: i. At least one light source (114) for generating illumination light (116) for illuminating the object (112), the light source (114) comprises at least one light emitting diode (118) and at least one luminescent material (120) for light conversion of primary light generated by the light emitting diode (118); 10 ii. At least one detector (128) for detecting the light (116, 130, 256) and thereby generating at least one detector signal; iii. At least one evaluation unit (136) configured to derive spectroscopy information about the object (112) from the at least one detector signal, the evaluation unit (136) being configured to derive spectroscopy information about the object (112) by taking into account the wavelength correction information.

Description

Technical Field

[0001] The present invention relates to a spectrometer device for obtaining spectroscopic information about at least one object, in particular for analyzing a sample, a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object, and a method for obtaining spectroscopic information about at least one object. The present invention further relates to a computer program and a non-transitory computer-readable medium. Such a device and method can generally be used for research or monitoring purposes, particularly in the infrared (IR) spectral region, especially in the near-infrared (NIR) spectral region, and in the visible (VIS) spectral region, for example, in spectral regions that allow simulation of human color vision capabilities. However, other applications are also possible. Background Art

[0002] Spectrometer devices are known to be efficient tools for obtaining information about the spectral properties of an object when it emits, irradiates, reflects and / or absorbs light. Spectrometer devices can therefore assist in analyzing samples or other tasks where information about the spectral properties of an object is of interest.

[0003] Typically, in a spectrometer, spectral information is obtained via one or more detectors and one or more wavelength-selective optical elements (e.g., one or more dispersive optical elements, filters (e.g., bandpass filters), prisms, gratings, interferometers, etc.). The detectors can include any type of photosensitive element, such as one or more single-pixel or multi-pixel detectors, line detectors, or array detectors with a one-dimensional or two-dimensional array of pixels. Furthermore, the spectrometer can include one or more light sources. Therefore, in spectroscopy, tunable light sources (e.g., lasers) and / or broadband emission light sources (e.g., halogen gas-filled bulbs and / or hot filaments) are commonly used. However, other light sources, such as light-emitting diodes, have also been proposed, either additionally or alternatively, for the visible spectral region.

[0004] In general, for spectrometers, particularly near-infrared spectrometers, calibration of the optical response is crucial for generating reliable spectroscopic information about an object. Calibration of the optical response (e.g., the responsivity of the detector and / or optical system) can be performed in the field using reference measurements. This allows the vertical axis of the resulting spectrum to be calibrated. The vertical axis typically includes information about the intensity of a specific wavelength. Typically, calibration of the wavelength information required to generate the spectrum (which can then be considered the x-axis of the spectrum) is performed at the factory using a light source with a known spectrum and / or reference samples. Due to aging of the equipment (e.g., optical components), factory calibration of the wavelength information can become ineffective. This can lead to unpredictable, systematic errors in the measurement results.

[0005] As an example, US 2010 / 208261 A1 describes an apparatus for determining at least one optical property of a sample. The apparatus includes a tunable excitation light source for applying excitation light to the sample. The apparatus also includes a detector for detecting detection light emitted from the sample. The excitation light source includes an array of light-emitting diodes, which is configured at least in part as a monolithic array of light-emitting diodes. The monolithic array of light-emitting diodes includes at least three light-emitting diodes, each light-emitting diode having a different emission spectrum.

[0006] US Pat. No. 8,164,050 B2 describes a multi-channel light source assembly for downhole spectroscopy. The assembly includes individual light sources that generate optical signals spanning a spectral range of wavelengths. A combining assembly optically combines the generated signals into a combined signal, while a routing assembly separates the combined signal into a reference channel and a measurement channel. Control circuitry electrically coupled to the light sources modulates each of the light sources at a unique or independent frequency during operation.

[0007] Furthermore, US 7,061,618 B2 describes integrated spectroscopy systems, in which, in some examples, an integrated tunable detector is provided using one or more Fabry-Perot tunable filters. Other examples use integrated tunable light sources that combine one or more diodes (such as superluminescent diodes (SLEDs)) with Fabry-Perot tunable filters or etalons.

[0008] Furthermore, US 5,475,221 A describes an optical device that uses an array of light emitting diodes controlled by a multiplexing scheme to replace conventional broadband light sources in devices such as spectrometers.

[0009] Spectrometers are often subject to various internal and external influences (such as environmental influences) that may affect the results of spectral measurements. To correct for and / or compensate for these influences, various calibration and / or correction methods are known. These calibration methods can be performed once or several times by the manufacturer, for example, under laboratory conditions. However, various online calibration techniques are also known, which can be performed by performing one or more calibration and / or correction steps between two spectral measurements or even during a measurement.

[0010] US 09360366 B1 discloses a self-referencing spectrometer that utilizes a shared aperture as an optical input to simultaneously automatically calibrate and measure the spectrum of a physical object. The simultaneous measurement and self-calibration capabilities enable it to be used as an accessory spectrometer on a mobile computing device, eliminating the need for offline calibration using an external reference light source. The acquired spectral information and captured images can be distributed via a wireless communication network via the mobile computing device.

[0011] DE 102014013848 B4 discloses a miniature spectrometer (specifically, an NIR miniature spectrometer for mobile applications in battery-powered terminals) to overcome the limitations of the aforementioned system configurations in terms of non-miniaturization and hand-holding. It also discloses a miniature spectrometer system and a calibration method. This miniaturized NIR spectrometer design does not require active temperature stabilization. Instead, according to the present invention, as part of a factory temperature calibration procedure, the spectral sensitivity function (QEλ = f(T); measured using an integrated temperature sensor) is recorded at several levels within the expected operating temperature range.

[0012] 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 comprises an interferometer optically coupled to receive an input beam and guide the input beam along a first optical path to generate a first interference beam and guide the input beam along a second optical path to generate a second interference beam, wherein each interference beam is generated before an output end of the interferometer. The spectrometer further comprises: a detector optically coupled to simultaneously detect a first interference signal generated from the first interference beam and a second interference signal generated from the second interference beam; and a processor configured to process the first interference signal and the second interference signal and to use the second interference signal as a reference signal when processing the first interference signal.

[0013] US 20210293620 A1 discloses a spectrometer comprising: an illumination device for illuminating a spectral measurement region; a detection unit for detecting electromagnetic radiation from the spectral measurement region; and a spectral element disposed in a beam path between the illumination device and the detection unit. The illumination device comprises: a light-emitting diode having a first central wavelength, the light-emitting diode being designed to emit first electromagnetic radiation having a first spectrum; and a light-emitting element for converting a first component of the first electromagnetic radiation having the first spectrum into second electromagnetic radiation having a second spectrum. The first central wavelength is 550 nm or 3000 nm, or has a value between 550 nm and 3000 nm. The first spectrum and the second spectrum overlap.

[0014] US 06667802 B2 discloses a method for calibrating a spectral detection system. The method includes: providing a plurality of packages, each of the plurality of packages containing a group of articles, wherein each group of articles has a known composition; measuring reflectance values ​​of each group of articles to thereby obtain a reference reflectance value set; normalizing the reference reflectance value set to thereby generate a normalized reference reflectance value set; and storing the normalized reference reflectance value set.

[0015] US 06717669 B2 discloses an automatically calibrated spectrometer and method that measures the transmission or reflectance of a sample as a function of wavelength without requiring lengthy calibration. A reflectance spectrometer and a transmission spectrometer, as well as an automatically calibrated method for use therewith, are disclosed. Light is focused onto a sample using a lens or similar optical element that transmits the light to the sample, reflects the light impinging on it, and transmits the light reflected from the sample. If the light reflected from the first lens and the sample is monitored, very useful information about the response of the system over time can be obtained. The reflected light from the first lens and the sample is monitored, and the reflected light is used to correct for changes in the system over time.

[0016] US 09448114 B2 discloses a spectrometer comprising a plurality of isolated optical channels, each of which comprises a plurality of isolated optical paths. The isolated optical paths reduce crosstalk between the optical paths, reduce the length of the spectrometer, and improve resolution. In many embodiments, the isolated optical paths comprise isolated parallel optical paths, which significantly reduce the length of the device. In many embodiments, each isolated optical path extends 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 comprises a plurality of sensor elements, wherein the position of the sensor element corresponds to a wavelength of received light, the wavelength being based on the angle of the light received at that position, the focal length of the lens, and the center wavelength of the filter.

[0017] US 2013 / 0093936 A1 discloses an energy dispersive device, spectrometer, and method for evaluating the composition of a substance in situ without the need for specialized training or expensive equipment. The energy dispersive device or spectrometer can be used with a digital camera or mobile phone. The device comprises a stack of monodispersive or bidispersive diffraction gratings that are rotated about their normals to produce multiple diffraction orders, based on which qualitative or quantitative properties of the substance can be meaningfully measured and determined.

[0018] US 2017 / 0153142 A1 discloses spectrometer methods and apparatus that improve accuracy and better accommodate variability between spectrometer systems and associated components. In many cases, one or more of a calibration cap, accessory, or spectrometer is associated with a unique identifier and corresponding calibration data. The calibration data associated with the unique identifier can be stored in a database that is used to determine spectral information based on measurements of an object obtained using various spectrometer devices. The spectrum of an object can be determined in response to the unique identifier and associated calibration data, thereby improving accuracy and reducing costs.

[0019] Despite the numerous advantages of known methods and devices, several technical challenges remain in the field of spectroscopy and spectroscopic devices, particularly in the near-infrared range. Consequently, there is a need for calibration techniques that correct for various influences, particularly those that can be performed online in the field (i.e., at the location where the spectral measurement is performed). Temperature is known to have a significant impact on the results and accuracy of spectral measurements. Temperature variations can occur due to external influences (such as changes in ambient temperature). Additionally or alternatively, temperature variations can result from internal influences (such as currents and resistances within the spectroscopic device, e.g., due to electrical power dissipation). These temperature variations can occur over short periods of time and / or manifest as long-term drift. Furthermore, it must be considered that temperature variations do not necessarily occur globally and / or when the entire spectrometer device is in thermal equilibrium. Consequently, localized temperature variations can occur, particularly at locations that are difficult to monitor, such as locations within the spectrometer device and / or at interfaces within its components (e.g., semiconductor interfaces). Furthermore, the temperature dependence of the system can change. For example, even if the temperature remains constant, a system may exhibit different performance over time (e.g. due to degradation, aging, or changes in optical or electrical interfaces from frequent use).

[0020] Problem to be solved

[0021] It is therefore desirable to provide a method and apparatus that at least partially addresses the above technical challenges and at least substantially avoids the disadvantages of known methods and apparatuses. In particular, the present invention aims to provide a spectrometer apparatus and method that are capable of correcting, in particular in situ, external and / or internal influences on the wavelength information required to generate spectroscopic information about an object. Summary of the Invention

[0022] This problem is solved by a spectrometer device for obtaining spectroscopic information about at least one object, a corresponding method, a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object, a computer program, and a non-transitory computer-readable medium having the features of the independent claims. Advantageous embodiments are listed in the dependent claims and throughout the description, which can be implemented individually or in any arbitrary combination.

[0023] In a first aspect, a spectrometer device for obtaining spectroscopic information about at least one object is disclosed. The spectrometer device comprises:

[0024] i. at least one light source for generating illumination light for illuminating an object, the light source comprising at least one light-emitting diode and at least one luminescent material for light conversion of the primary light generated by the light-emitting diode;

[0025] ii. at least one detector for detecting detection light from an object generated by at least one light source, and thereby generating at least one detector signal;

[0026] iii. At least one evaluation unit configured to derive spectroscopic information about the object from the at least one detector signal, wherein the evaluation unit is configured to derive spectroscopic information about the object by taking into account wavelength correction information, in particular, derived from the at least one detector signal.

[0027] As used herein, the term "spectrographic device" is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a special or customary meaning. The term may specifically, but is not limited to, refer to an optical device configured to obtain at least one item of spectral information about at least one object. Specifically, the at least one spectral information item may refer to at least one optical property or optically measurable property determined as a function of wavelength for one or more different wavelengths. More specifically, the optical property or optically measurable property and the at least one spectral information item may relate to at least one property that characterizes at least one of transmission, absorption, reflection, and emission of the at least one object, either intrinsically or after exposure to external light. The at least one optical property may be determined for one or more wavelengths. The spectroscopic device may specifically be a device capable of recording signal intensities for corresponding wavelengths or subregions (e.g., wavelength intervals) of a spectrum, wherein the signal intensities may be provided as electrical signals that can be used for further evaluation.

[0028] By way of example, a spectrometer device may be or may include a device that allows for measuring at least one spectrum (e.g., for measuring spectral flux, in particular as a function of wavelength or detection wavelength). By way of example, the spectrum may be acquired in absolute units or relative units (e.g., relative to at least one reference measurement). Thus, by way of example, the acquisition of at least one spectrum may specifically focus on measuring spectral flux (in W / nm) or a spectrum (in W) relative to at least one reference material, which may describe a material property (e.g., a change in reflectivity with wavelength). Additionally or alternatively, the reference measurement may be based on a reference light source, an optical reference path, a calculated reference signal (e.g., a calculated reference signal from literature), and / or a reference device.

[0029] Specifically, at least one spectrometer device may be a diffuse reflectance spectrometer device configured to obtain spectral information from light diffusely reflected by at least one object (e.g., at least one sample). Additionally or alternatively, at least one spectrometer device may be or may include an absorption spectrometer and / or a transmission spectrometer. In particular, measuring a spectrum with the spectrometer device may include measuring absorption in a transmission configuration. Specifically, the spectrometer device may be configured to measure absorption in a transmission configuration. However, as outlined above, other types of spectrometer devices are also possible.

[0030] Specifically, and as will be further detailed below, at least one spectrometer device can include at least one light source, which can be, for example, at least one of a tunable light source, a light source having at least one fixed emission wavelength, and a broadband light source. As will be further detailed below, the spectrometer device further includes at least one detector device configured to detect light, such as at least one of light transmitted, reflected, or emitted from at least one object. As will be further detailed below, the spectrometer device can further include at least one wavelength-selective element, such as at least one of a grating, a prism, and a filter (e.g., a variable-length filter having varying transmission characteristics across its lateral extension). The wavelength-selective element can be used to separate incident light into a spectrum of component wavelength signals, the respective intensities of which are determined using a detector (e.g., a detector array as described in more detail below).

[0031] The spectrometer device may specifically be a portable spectrometer device. As used herein, the term "portable" is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, the property of at least one object being moved by human power (such as by a single user). In particular, the weight of the object characterized by the term "portable" may not exceed 10 kg, specifically not exceed 5 kg, more specifically not exceed 1 kg or even not exceed 500 g. Additionally or alternatively, the size of the object characterized by the term "portable" may be such that the object extends no more than 0.3 m in any dimension, specifically no more than 0.2 m in any dimension. In particular, the volume of the object may not exceed 0.03 m³, specifically not more than 0.01 m³, more specifically not more than 0.001 m³ or even not more than 500 mm 3 . In particular, as an example, the portable spectrometer device may have dimensions of, for example, 10 mm × 10 mm × 5 mm. In particular, the portable spectrometer device may be part of a mobile device, such as a laptop computer, a tablet computer, a mobile phone (such as a smartphone), a smartwatch and / or a wearable computer (also referred to as a “wearable device”, such as a body-worn computer (such as a wristband or a watch)), or may be attachable to a mobile device. In particular, the weight of the spectrometer device, in particular the portable spectrometer device, may be in the range of 1 g to 100 g, more particularly in the range of 1 g to 10 g.

[0032] As used herein, the term "spectroscopy information" (also referred to as "spectral information" or "spectral information item") is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a special or customary meaning. The term may specifically, but is not limited to, an item of information about at least one object and / or radiation emitted by at least one object, characterizing at least one optical property of the object, more specifically, characterizing, for example, at least one item of information that qualitatively and / or quantifies at least one of the transmission, absorption, reflection, and emission of the at least one object. By way of example, at least one item of spectral information may include at least one item of intensity information, such as information about the intensity of at least one of light transmitted, absorbed, reflected, or emitted by the object, for example, as a function of wavelength or wavelength sub-range within one or more wavelengths (e.g., within a wavelength range). Specifically, the intensity information may correspond to, or be derived from, a signal intensity (particularly an electrical signal) recorded by a spectrometer device that is associated with a wavelength or wavelength range of the spectrum.

[0033] The spectrometer device can be specifically configured to acquire at least one spectrum, or at least a portion of a spectrum, of detection light propagating from the object to the spectrometer. The spectrum can describe a radiometric unit of spectral flux, for example given in watts per nanometer (W / nm), or in other units, for example as a function of the wavelength of the detection light. Thus, the spectrum can describe the optical power of light within a specific wavelength band, for example in the NIR spectral range. The spectrum can include one or more optical variables that vary with wavelength, such as power spectral density, an electrical signal obtained by optical measurement, etc. As an example, the spectrum can indicate the power spectral density and / or spectral flux of the object (e.g., a sample), for example relative to a reference sample, such as the transmittance and / or reflectance of the object (particularly the sample).

[0034] As an example, the spectrum may include at least one measurable optical variable or property of the detection light and / or the object, the optical variable or property being in particular a function of the illumination light and / or the detection light. As an example, the at least one measurable optical variable or property may include at least one radiometric quantity, such as at least one of spectral density, power spectral density, spectral flux, radiant flux, radiant intensity, spectral radiant intensity, irradiance, and spectral irradiance. Specifically, as an example, the spectrometer device (in particular the detector) may measure power in Watts per square meter (W / m 2 ) or more specifically measured in watts per square meter per nanometer (W / m 2 Based on the measured quantities, the spectral flux in Watts per nanometer (W / nm) and / or the radiant flux in Watts (W) can be determined (e.g., calculated) by taking into account the area of ​​the detector.

[0035] As used herein, the term "object" is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, any body selected from animate objects and inanimate objects. Thus, by way of example, at least one object may include one or more items and / or one or more parts of an item, wherein at least one item or at least one part thereof may include at least one component that can provide a spectrum suitable for investigation. Additionally or alternatively, an object may be or may include one or more organisms and / or one or more parts thereof, such as one or more body parts of a human (e.g., a user) and / or an animal. In particular, an object may include at least one sample that can be analyzed in whole or in part by spectroscopic methods. By way of example, an object may be or may include at least one of the following: human or animal skin; edibles, such as fruit; plastics; and textiles.

[0036] The spectrometer includes 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 photoconverting primary light generated by the light emitting diode.

[0037] As further used herein, the term "light" is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customary meaning. The term may specifically refer to, but is not limited to, electromagnetic radiation in one or more of the infrared spectral range, the visible spectral range, and the ultraviolet spectral range. As used herein, the term "ultraviolet spectral range" generally refers to electromagnetic radiation having a wavelength of 1 nm to 380 nm, preferably 100 nm to 380 nm. Furthermore, in accordance in part with the version of standard ISO-21348 in effect as of the date of this document, the term "visible spectral range" generally refers to the spectral range of 380 nm to 760 nm. The term "infrared spectral range" (IR) generally refers to electromagnetic radiation in the range of 760 nm to 1000 µm, of which the range of 760 nm to 1.5 µm is generally referred to as the "near infrared spectral range" (NIR), the range of 1.5 µm to 15 µm is referred to as the "mid infrared spectral range" (MidIR), and the range of 15 µm to 1000 µm is referred to as the "far infrared spectral range" (FIR). Preferably, the light used for the typical purposes of the present invention is light in the infrared (IR) spectral range, more preferably light in the near-infrared (NIR) and / or mid-infrared (MidIR) spectral range, particularly light with a wavelength of 1 µm to 5 µm, preferably 1 µm to 3 µm. This is because many material properties or chemical composition characteristics of an object can be derived from the NIR spectral range. However, it should be noted that spectral analysis in other spectral ranges is also applicable and falls within the scope of the present invention.

[0038] Therefore, as used herein, the term "light source" (also referred to as "illumination source") is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, any device configured to generate or provide light in the sense defined above. The light source may specifically be or may include at least one electric light source, such as an electrically driven light source.

[0039] As will be further described below, the light source can generally be implemented in a variety of ways. Thus, for example, the light source can be part of the spectrometer device within the spectrometer device housing. Alternatively or additionally, however, the at least one light source can also be arranged external to the housing, for example as a separate light source. The light source can be arranged separately from the object and illuminate the object from a distance.

[0040] In spectroscopy, it is important to distinguish between various light sources and light paths. In the context of the present invention, the nomenclature used first refers to light propagating from a light source to an object as "illuminating light" (or "illumination light"). Secondly, light propagating from an object to a detector is referred to as "detection light." Detection light can include at least one of the following: illumination light reflected by an object, illumination light scattered by an object, illumination light transmitted by an object, or luminescence light generated by an object (e.g., phosphorescence or fluorescence generated by an object after optical, electrical, or acoustic excitation of the object by the illumination light). Therefore, detection light can be generated directly or indirectly by illumination of an object with illumination light.

[0041] Furthermore, as will be described in more detail below, within the light source itself, a distinction can be made between various light sources, such as primary and secondary light sources. Thus, "primary light" (also referred to as "pump light"), as will be described in more detail below, can be generated by a primary light source (such as at least one light-emitting diode) and can subsequently be transformed into "secondary light," such as by using light conversion (e.g., via one or more phosphor materials). The illumination light can be or include at least one of the primary light or a portion thereof, the secondary light or a portion thereof, or a mixture of the primary and secondary light.

[0042] Therefore, as used herein, the term "illumination" is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, the process of exposing at least one element to light.

[0043] As outlined above, the light source comprises at least one light-emitting diode and at least one luminescent material for photoconverting primary light generated by the light-emitting diode, wherein, in particular, the illumination light may be a combination of the primary light and the light generated by photoconversion of the luminescent material or light generated by photoconversion of the luminescent material (also referred to as secondary light).

[0044] As used herein, the term "light emitting diode," or simply "LED," is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not to be limited to a special or customary meaning. The term may specifically refer to, but is not limited to, an optoelectronic semiconductor device capable of emitting light when an electric current flows through the device. Optoelectronic semiconductor devices can be configured to generate light due to one or more of a variety of physical processes, including spontaneous emission, induced emission, decay of metastable excited states, and the like. Thus, by way of example, a light emitting diode may include one or more of the following: a light emitting diode based on spontaneous emission of light (particularly an organic light emitting diode), a superluminescent light emitting diode (sLED), or a laser diode (LD). Hereinafter, without narrowing down the possible embodiments of a light emitting diode to any of the aforementioned physical principles or setups, the abbreviation "LED" will be used for any type of light emitting diode. Specifically, an LED may include at least two layers of semiconductor material, wherein light may be generated at at least one interface between the at least two semiconductor material layers, particularly due to the recombination of positive and negative charges (e.g., electron-hole recombination). The at least two semiconductor material layers may have different electrical properties, such as at least one of the layers being an n-doped semiconductor material and at least one of the layers being a p-doped semiconductor material. Thus, as an example, an LED may include at least one pn junction and / or at least one pin structure. However, it should be noted that other device structures are also possible. The at least one semiconductor material may specifically be or may include at least one inorganic semiconductor material. However, it should be noted that organic semiconductor materials may be used in addition or alternatively.

[0045] Typically, as will be further detailed below, an LED can convert electrical current into light, specifically into primary light, more specifically into blue primary light. Thus, the LED can specifically be a blue LED. The LED can be configured to generate primary light, also referred to as "pump light." Thus, the LED can also be referred to as a "pump LED." The LED can specifically include at least one LED chip and / or at least one LED die. Thus, the semiconductor element of the LED can include a bare LED chip.

[0046] Various types of LEDs suitable for generating primary light are known to those skilled in the art and can also be used in the present invention. In particular, pn junction diodes can be used. By way of example, one or more LEDs selected from the group consisting of indium gallium nitride (InGaN)-based LEDs, GaN-based LEDs, InGaN / GaN alloy-based LEDs, or combinations thereof, and / or other LEDs can be used. Additionally or alternatively, quantum well LEDs, such as one or more quantum well LEDs based on InGaN, can also be used. Additionally or alternatively, superluminescent LEDs (sLEDs) and / or quantum cascade lasers can be used.

[0047] As used herein, the term "luminescence" is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, the process of spontaneous emission of light by a substance that is not caused by heat. In particular, luminescence may refer to radiation from a cold body. More specifically, luminescence may be initiated or stimulated by irradiation with light, in which case luminescence is also referred to as "photoluminescence". In the context of the present invention, the property of a material that is capable of luminescence is referred to by the adjective "luminescent". At least one luminescent material may specifically be a photoluminescent material, i.e. a material that is capable of emitting light after absorbing a photon or excitation light. In particular, the luminescent material may have a positive Stokes shift, which generally may refer to the fact that the secondary light is red-shifted relative to the primary light.

[0048] Thus, at least one luminescent material can form at least one converter (also called a light converter) that converts primary light into secondary light having different spectral characteristics than the primary light. Specifically, the spectral width of the secondary light can be greater than the spectral width of the primary light and / or the emission center of the secondary light can be shifted (specifically, red-shifted) compared to the primary light. Specifically, at least one luminescent material can have absorption in the ultraviolet and / or blue spectral ranges and emission in the near-infrared and / or infrared spectral ranges. Thus, typically, the luminescent material or converter can form at least one component of a phosphor LED, which concentrates primary light or pump light, particularly in the blue spectral range, into light having a longer wavelength, for example, in the near-infrared or infrared spectral range.

[0049] Various types of conversion and / or luminescence are known and can be used in the context of the present invention. Thus, in particular, the conversion can occur via a dipole-allowed transition in the luminescent material (also known as fluorescence) and / or via a dipole-forbidden, and therefore longer-lived, transition in the luminescent material (often also known as phosphorescence).

[0050] Thus, the luminescent material may specifically form at least one converter or light converter. The luminescent material may form at least one of a converter sheet, a luminescent coating (specifically a fluorescent coating) on ​​an LED, and a phosphor coating on an LED. As an example, the luminescent material may include one or more of the following materials: cerium-doped YAG (YAG:Ce 3+ or Y3Al5O 12 :Ce 3+ ); rare earth-doped Sialon; copper and aluminum co-doped zinc sulfide (ZnS:Cu,Al).

[0051] Together, an LED and a luminescent material can form a so-called "phosphor LED." Therefore, as used herein, the term "phosphor light-emitting diode," or simply "phosphor LED," is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a special or customary meaning. The term may specifically, but is not limited to, the combination of at least one light-emitting diode configured to generate primary light, or pump light, and at least one luminescent material (also referred to as a "phosphor") configured to photoconvert the primary light generated by the light-emitting diode. A phosphor LED can form a packaged LED light source comprising an LED die (e.g., a blue LED emitting blue pump light) and a phosphor that, for example, fully or partially coats the LED and, for example, is configured to convert the primary light, or blue light, into light with different spectral characteristics (specifically, into near-infrared light). Typically, a phosphor LED can be packaged in a housing or unpackaged. Thus, the LED and the at least one luminescent material for photoconverting the primary light generated by the light-emitting diode can be housed in a common housing. Alternatively, however, the LED may also be an unpackaged or bare LED, which may be fully or partially covered with luminescent material, such as by providing one or more layers of luminescent material on the LED die.A phosphor LED may typically form the emitter or light source itself.

[0052] In a light source (particularly a phosphor LED), at least one luminescent material can be positioned relative to a light-emitting diode (LED) such that heat can be transferred from the diode to the luminescent material. More specifically, the luminescent material can be positioned such that heat can be transferred via one or both of thermal radiation and thermal conduction (more preferably thermal conduction). Thus, by way of example, the luminescent material can be in thermal and / or physical contact with the light-emitting diode. By way of example, the luminescent material can form one or more coatings or layers that are in contact with or in close proximity to the light-emitting diode, such as contact with one or more of the semiconductor materials of the light-emitting diode. Thus, the temperature of the luminescent material and the temperature of the light-emitting diode can generally be coupled.

[0053] The at least one luminescent material can specifically form at least one layer. In general, various alternative approaches to positioning the luminescent material relative to the LED are possible, which can be used individually or in combination. First, the luminescent material (e.g., at least one layer of luminescent material, such as a phosphor) can be positioned directly on the LED, also referred to as "direct attachment," e.g., with no material between the LED and the luminescent material, or with one or more transparent materials between them, such as one or more transparent materials (particularly transparent to the primary light) between the LED and the luminescent material. Thus, by way of example, a coating of luminescent material can be placed directly or indirectly on the LED. Additionally or alternatively, by way of example, the luminescent material can form at least one converter, such as at least one converter disk, which can be placed on top of the LED, for example, by attaching the converter to the LED with an adhesive. Additionally or alternatively, the luminescent material can also be positioned remotely, such that the primary light from the LED must traverse an intermediate light path before reaching the luminescent material. This placement can also be referred to as "remote placement" or "remote phosphor." Similarly, by way of example, a remotely positioned luminescent material can form a solid or converter, such as a disk or converter disk. Furthermore, in the case of remote placement, the luminescent material can also be a coating. In particular, a light-transmitting object (e.g., a thin glass substrate, a module window) comprising and / or made of glass or plastic can be coated with a phosphor. Alternatively, a reflective surface can be coated with a phosphor. This can be a flat or rough reflector, which can comprise and / or be made of a substrate of a highly reflective material (e.g., silicon), or a flat or rough surface (e.g., glass or plastic) coated with gold, silver, aluminum, or chromium. One or more optical elements, such as lenses, prisms, gratings, reflectors, apertures, or combinations thereof, can be placed in the intermediate light path. Specifically, an optical system with imaging properties can be placed in the intermediate light path, between the LED and the luminescent material. Thus, for example, the primary light can be focused or concentrated onto the converter.

[0054] At least one spectrometer device may include at least one drive unit for electrically driving a light source. As used herein, the term "drive" is a broad term and is to be given its ordinary and conventional meaning to those skilled in the art and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, the process of providing one or both of at least one control parameter and / or electrical power to another device. Therefore, as used herein, the term "drive unit" is a broad term and is to be given its ordinary and conventional meaning to those skilled in the art and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, any device or combination of devices configured to provide one or both of at least one control parameter and / or electrical power to another device (e.g., in this example, at least one light source). For example, the drive unit may be specifically configured to at least one of measure and control one or more electrical parameters of the electrical power supplied to the light source (specifically, to at least one light-emitting diode). As an example, the drive unit may be configured to supply current to an LED, specifically to control the current through the LED. For example, the drive unit may be configured to adapt and measure the voltage supplied to the LED required to achieve a specific current through the LED. The measurement unit (e.g., a driver unit) may specifically include one or more of the following: a current source, a voltage source, a current measuring device (e.g., an ammeter), a voltage measuring device (e.g., a voltmeter), or a power measuring device. Specifically, the driver unit may include at least one current source for providing at least one predetermined current to the LED. The current source may be configured to adjust or control the voltage applied to the LED to generate the predetermined current. As an example, the driver unit may include one or more electrical components (e.g., an integrated circuit) for driving the light source. The driver unit may be fully or partially integrated into the light source, or may be separate from the light source.

[0055] As further outlined above, the spectrometer device comprises at least one detector for detecting detection light from the object generated by at least one light source and thereby generating at least one detector signal.

[0056] As used herein, the verb "detect" is a broad term and is to be given its ordinary and conventional meaning to those skilled in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, the process of at least one of qualitatively and / or quantitatively determining, measuring, and monitoring at least one parameter (such as at least one of a physical parameter, a chemical parameter, and a biological parameter). Specifically, a physical parameter may be or may include an electrical parameter. Therefore, as used herein, the term "detector" is a broad term and is to be given its ordinary and conventional meaning to those skilled in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, any device configured to detect, i.e., to at least one of qualitatively and / or quantitatively determine, measure, and monitor at least one parameter (such as at least one of a physical parameter, a chemical parameter, and a biological parameter). A detector may be configured to generate at least one detector signal, more specifically at least one electrical detector signal, such as an analog and / or digital detector signal, that provides information about the at least one parameter measured by the detector. The detector signal may be provided directly or indirectly by the detector to an evaluation unit, such that the detector and the evaluation unit may be directly or indirectly connected. The detector signal may be used as a "raw" detector signal and / or may be processed or pre-processed (e.g. by filtering etc.) before further use. Thus, the detector may comprise at least one processing device and / or at least one pre-processing device, such as at least one of an amplifier, an analog / digital converter, an electrical filter and a Fourier transform.

[0057] In this example, the detector is configured to detect light, such as, but not limited to, illumination light from a light source and / or detection light from an object; and / or light from at least one reference target. According to the above nomenclature, light that propagates from the object to the spectrometer device, or more specifically, to the detector of the spectrometer device, is referred to as "detection light."

[0058] Specifically, the detector may therefore be or may include at least one optical detector. The optical detector may be configured to determine at least one optical parameter, such as the intensity and / or power of light irradiating at least one sensitive area of ​​the detector. More specifically, the optical detector may include at least one photosensor and / or at least one optical sensor, such as at least one of a photodiode, a photocell, a photoresistor, a phototransistor, a thermopile sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier, and a bolometer. The detector may therefore be configured to generate at least one detector signal, more specifically at least one electrical detector signal in the aforementioned sense, which provides information about at least one optical parameter, such as the power and / or intensity of light irradiating the detector or a sensitive area of ​​the detector.

[0059] The detector may include a single optically sensitive element or region or a plurality of optically sensitive elements or regions. In particular, the detector may be or may include at least one detector array (more particularly an array of photosensitive elements), as will be described in further detail below. Each photosensitive element may include at least a photosensitive region, which may be adapted to generate an electrical signal depending on the intensity of incident light, wherein the electrical signal may in particular be provided to an evaluation unit, as will be described in further detail below.

[0060] The photosensitive area comprised by each optically sensitive element may in particular be a single, homogeneous photosensitive area configured to receive incident light impinging on the respective optically sensitive element. However, other arrangements of the optically sensitive elements are also conceivable.

[0061] The array of optically sensitive elements can be designed to generate a detector signal, preferably an electronic signal, which is associated with the intensity of the incident light impinging on the individual optically sensitive elements. The detector signal can be an analog signal and / or a digital signal. Accordingly, the electronic signals of adjacent pixelated sensors can be generated simultaneously or in a temporally consecutive manner. For example, during a row scan or line scan, a series of electronic signals can be generated corresponding to a series of individual optically sensitive elements arranged in a row. In addition, these individual optically sensitive elements can preferably be active pixel sensors, which can be suitable for amplifying the electronic signals before providing them to the evaluation unit. For this purpose, the detector can include one or more signal processing devices, such as one or more filters and / or analog-to-digital converters, for processing and / or preprocessing the electronic signals.

[0062] In the case where the detector comprises an array of optically sensitive elements, the detector can, by way of example, be selected from any known pixelated sensor, in particular, from pixelated organic camera elements, preferably pixelated organic camera chips, or from pixelated inorganic camera elements, preferably pixelated inorganic camera chips, more preferably from CCD chips or CMOS chips, which are the types commonly used in various cameras today. Alternatively, the detector can generally be or include a photoconductor, in particular an inorganic photoconductor, especially PbS, PbSe, Ge, InGaAs, extended InGaAs, InSb, or HgCdTe. As another alternative, the detector can include at least one of a pyroelectric element, a bolometer element, or a thermopile detector element. Thus, a camera chip having a matrix of 1 × N pixels or M × N pixels can be used, where, by way of example, M can be <10 and N can be in the range of 1 to 50, preferably 2 to 20, and more preferably 5 to 10. Furthermore, a monochrome camera element, preferably a monochrome camera chip, can be used, wherein the monochrome camera element can be selected differently for each optically sensitive element, in particular depending on the wavelength that varies across a range of optical sensors.

[0063] Hence, the array may be adapted to provide a plurality of electrical signals which may be generated by the photosensitive areas of the optically sensitive elements comprised by the array.The electrical signals provided by the array of the spectrometer device may be forwarded to an evaluation unit.

[0064] As described above, the at least one evaluation unit is configured to derive spectroscopic information about the object from the at least one detector signal, wherein the evaluation unit is configured to derive spectroscopic information about the object by taking into account in particular wavelength correction information derived from the at least one detector signal.

[0065] As further described above, the spectrometer apparatus includes at least one evaluation unit for evaluating at least one detector signal generated by a detector and for deriving spectroscopic information about the object from the detector signal. As used herein, the term "evaluation" is a broad term and is to be given its ordinary and conventional meaning for those skilled in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, the process of processing at least one first information item to thereby generate at least one second information item. Therefore, as used herein, the term "evaluation unit" is a broad term and is to be given its ordinary and conventional meaning for those skilled in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, any device or combination of devices configured to evaluate or process at least one first information item to generate at least one second information item thereof. Thus, in particular, the evaluation unit may be configured to process at least one input signal and generate at least one output signal thereof. By way of example, the at least one input signal may include at least one detector signal provided directly or indirectly by at least one detector and at least one signal provided directly or indirectly by a measurement unit, which may, for example, be a component of a drive unit, the signal including at least one information item regarding at least one electrically measurable quantity (particularly a forward voltage).

[0066] By way of example, the evaluation unit may be or may include one or more integrated circuits (such as one or more application-specific integrated circuits (ASICs)) and / or one or more data processing devices (such as one or more computers, digital signal processors (DSPs), and field-programmable gate arrays (FPGAs)), preferably one or more microcomputers and / or microcontrollers. Additional components may be included, such as one or more preprocessing devices and / or data acquisition devices, such as one or more devices for receiving and / or preprocessing detector signals, such as one or more A / D converters and / or one or more filters. Furthermore, the evaluation unit may include one or more data storage devices. Furthermore, the evaluation unit may include one or more interfaces, such as one or more wireless interfaces and / or one or more wired interfaces.

[0067] At least one evaluation unit can be adapted to execute at least one computer program, such as at least one computer program that performs or supports the information item generation step. For example, one or more algorithms can be implemented that, using at least one detector signal and at least one information item about at least one electrically measurable quantity (particularly the forward voltage) as input variables, can perform a predetermined transformation to obtain spectroscopic information about the object, such as a corrected spectrum and / or at least one item of spectroscopic information describing at least one characteristic of the object. To this end, the evaluation unit can particularly include at least one data processing device (also referred to as a processor, particularly an electronic data processing device) designed to generate the desired information by evaluating the detector signal and the information item about the at least one electrically measurable quantity (particularly the forward voltage). The evaluation unit can use any desired process to generate the desired information, such as calculation and / or using at least one stored and / or known relationship. The evaluation unit can specifically be configured to perform at least one digital signal processing (DSP) technique, particularly at least one Fourier transform, on the primary detector signal or any secondary detector signals derived therefrom. Additionally or alternatively, the evaluation unit can be configured to perform one or more additional digital signal processing techniques on the primary detector signal or any secondary detector signals derived therefrom, such as windowing, filtering, the Goertzel algorithm, cross-correlation, and autocorrelation. In addition to the detector signal and information about at least one electrically measurable quantity (particularly the forward voltage), one or more additional parameters and / or information items may also influence the relationship. This relationship can be determined or determinable empirically, analytically, or semi-empirically. By way of example, the relationship can include at least one of a model or calibration curve, at least one set of calibration curves, at least one function, or a combination of the aforementioned possibilities. The one or more calibration curves can be stored, for example, in a data storage device and / or table, for example, as a set of values ​​and their associated function values. Alternatively or additionally, however, at least one calibration curve can also be stored, for example, in parameterized form and / or as a functional equation. A single relationship can be used to process the detector signal into information items. Alternatively, at least one combined relationship for processing the detector signal is feasible. Various possibilities are contemplated, and these possibilities can also be combined.

[0068] As outlined above, the evaluation unit can be specifically configured, for example through software programming, to determine at least one correction based on items of wavelength correction information. As used herein, the term "wavelength correction information" is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a specific or customary meaning. The term can specifically, but not limited to, information regarding wavelength information used to correct spectroscopic information about an object. The wavelength correction information can be, or can be generated from, a known characteristic (particularly a known emission peak of an emission spectrum of a light source). The wavelength correction information can be obtained by comparing a measured wavelength of a characteristic (particularly the wavelength of a measured emission peak of the characteristic) with a known wavelength of the characteristic (particularly the known wavelength of the emission peak of the characteristic). The characteristic (particularly the emission peak) can be determined based on the power density distribution of light generated by the light source. The light generated by the light source can be illumination light. Alternatively or additionally, the light generated by the light source can be detection light from the object and / or light from a reference target. Different light sources can be generated. By taking into account the wavelength correction information, the relationship between at least one item of intensity information and at least one wavelength or at least one wavelength sub-range within one or more wavelength ranges can be corrected.

[0069] Thus, as an example, the evaluation unit can be configured to determine a spectrum, such as a spectrum indicating a wavelength-dependent photometric or radiometric parameter, from at least one detector signal provided by the detector. The spectrum can be corrected by applying at least one correction function (e.g., a correction factor, such as a wavelength-dependent correction factor of the correction function) to the spectrum, thereby generating a corrected spectrum. As an example, the detector signal can provide a signal as a function of the wavelength of the detected light, wherein, by using the correction, each function value of the detector signal can be assigned to a corrected wavelength and / or wavelength range.

[0070] By way of example, the detector signal may include multiple detector signals that are at least a function of the wavelength of the detection light and, optionally, also a function of time, particularly for time-dependent detector signals. The multiple detector signals may form a spectrum, including options for digital or analog spectra. Thus, by way of example, each detector signal may summarize information from a predetermined spectral range defined by the spectral resolution of the detector. The detector may include multiple photosensors, each sensitive to and / or exposed to a different portion of the spectrum of the detection light within a different spectral range. The detector signals of all the photosensitive elements may form the detector signal, or, by way of example, collectively define the spectral information, a portion thereof, or a precursor thereof. The sensitivity spectral range of each photosensitive element may be known, and the intensity of the detection light as a function of the detection wavelength may be derived from this detector signal by combining data pairs for each photosensitive element, each data pair comprising the corresponding signal of the photosensitive element and the sensitivity wavelength. In particular, due to aging, the sensitivity spectral range of each photosensitive element may change, for example, narrowing and / or widening and / or shifting. This can be compensated for by taking into account wavelength correction information.

[0071] At least one or each sensitivity spectral range of at least one or each photosensor can be corrected by using a corresponding correction factor for the respective wavelength, wherein the correction factor, which can be determined by evaluating the wavelength correction information, can be provided by the evaluation unit.

[0072] Therefore, as generally used herein, the term "calibration" is a broad term and is to be given its ordinary and conventional meaning to one of ordinary skill in the art and is not limited to a specific or customized meaning. The term may specifically refer to, but is not limited to, the modification or process of modifying at least one item of interest based on one or more information items indicating parameters known to have an impact on the item of interest. Thus, a measured spectrum can be corrected in such a way that the corrected spectrum corresponds to a spectrum under precisely known conditions or standardized conditions. Thus, the corrected spectrum can be compared with a reference spectrum determined under precisely known conditions or standardized conditions. As an example, correction can include modifying the measured spectrum included in the detector signal to correspond to standardized conditions. Such standardized conditions can be defined by known characteristic positions in the power spectral density distribution of wavelengths, particularly emission peak positions, more particularly emission peak positions of at least one emission band. The term "position" can refer to a specific wavelength and / or a range of wavelengths. Correction can include assigning at least one item of intensity information at a specific wavelength in the measured spectrum to a different wavelength in the corrected spectrum, such as the corrected wavelength.

[0073] Thus, step iii. may include a calibration in which the measured spectrum derived from the detector signal is modified to correspond to a calibrated spectrum, in particular a calibrated spectrum that may have been obtained under predetermined standard conditions. The standardization conditions may be defined by using appropriate conditions, such as known characteristic positions (in particular emission peak positions). However, other standard conditions are also feasible.

[0074] In order to determine the correction factor, in particular the correction function, one or more calibration measurements can be performed. These calibration measurements can be performed online and / or on site. Thus, the correction can be based on one or more calibration measurements. As an example, these calibration measurements can determine at least one detector signal that varies with wavelength. As outlined above, at least one condition can be determined as a standard condition. For example, a known characteristic position in the power spectral density distribution of the wavelength, in particular the emission peak position, more particularly the emission peak position of at least one emission band. By determining the ratio between the characteristic position (in particular the emission peak position) in the measured spectrum and the characteristic position (in particular the emission peak position) in the spectrum obtained under standard conditions, the correction factor for each wavelength can be determined.

[0075] As further outlined above, the evaluation unit can be configured to correct at least one wavelength and / or wavelength scale of the spectroscopic information by assigning at least one detector signal to a corrected wavelength using a correction. Thus, as an example, the evaluation unit can be configured, for example by software programming, to directly or indirectly transform at least one wavelength and / or wavelength range of a spectrum obtained, for example, from the at least one detector signal into at least one corrected wavelength and / or wavelength range, for example into a corrected spectrum. As an example and as further outlined above, the correction can specifically comprise multiplying the wavelength and / or wavelength range assigned to the at least one detector signal or a part thereof by a different wavelength and / or wavelength range. Thereby, a spectral correction taking into account the wavelength correction information can be performed. The evaluation unit can specifically be configured to obtain the spectroscopic information using the corrected wavelength information.

[0076] As an example, the detector can be configured to generate detector signals for at least one spectral range of light from the object (in particular, for at least two different spectral ranges), in a manner at least one of sequential and simultaneous. For example, as outlined above, the detector can include an array of photosensitive elements, wherein each photosensitive element can be sensitive to and / or exposed to light in a different spectral range. The evaluation unit can be configured to individually correct the wavelengths and / or wavelength ranges assigned to the detector signals in the different spectral ranges, and to combine the individually corrected assignments to obtain spectroscopic information. Thus, the individual detector signals assigned to the individually corrected wavelengths can be combined, for example, to generate a corrected spectrum.

[0077] Thus, in general, the detector may comprise an array of photosensitive elements, wherein each photosensitive element may be configured to generate at least one detector signal for a specific wavelength or wavelength range. The evaluation unit may generally be configured to individually correct each specific wavelength or wavelength range assigned to the detector signal, and to combine the detector signals to obtain the spectroscopic information. Thus, in particular, if each photosensitive element is sensitive to light in a different spectral range and / or is exposed to light in a different spectral range, for example, via one or more suitable filters in the beam path of the detection light, the wavelength correction information may be individually taken into account for each photosensitive element as an influence of the correction parameter.

[0078] As outlined above, the photosensitive elements can be sensitive to different spectral ranges of the light from the object. Different spectral sensitivities can be implemented by using photosensitive elements with inherently different spectral sensitivities, such as by using different integrated filters and / or different sensitive materials (e.g., semiconductor materials). Additionally or alternatively, different spectral sensitivities can be achieved by using one or more wavelength-selective elements (e.g., one or more filters, gratings, prisms, etc.) in one or more beam paths of the detection light, the one or more wavelength-selective elements being configured to allow different spectral portions of the detection light from the object to reach each photosensitive element sequentially or simultaneously.

[0079] The light-emitting diode may have a primary emission range that lies at least partially in the spectral range of 420 nm to 460 nm, more specifically in the range of 440 nm to 455 nm, more specifically at 440 nm. The luminescent material may be a phosphor. The illumination light may have a spectral range that lies at least partially in the near-infrared spectral range, specifically in the spectral range of 1 to 3 μm, preferably 1.3 to 2.5 μm, and more preferably 1.5 to 2.2 μm.

[0080] The detector may be configured to generate detector signals for at least two different spectral ranges of light from the object, at least one of sequentially and simultaneously, to obtain spectroscopic information. The detector may include an array of photosensitive elements, wherein each photosensitive element is configured to generate at least one detector signal to obtain spectroscopic information. The spectrometer device may be configured such that the photosensitive elements are sensitive to different spectral ranges of the light from the object. The spectrometer device may include at least one filter element arranged in a beam path of the light from the object, wherein the filter element may be configured such that each photosensitive element is exposed to a separate spectral range of the light from the object.

[0081] The spectrometer apparatus may further include at least one wavelength selective element, the wavelength selective element may include at least one of a wavelength selective element disposed in the beam path of the illumination light and a wavelength selective element disposed in the beam path of the detection light. The wavelength selective element may be selected from the group consisting of a tunable wavelength selective element and a wavelength selective element having a fixed transmission spectrum.

[0082] Therefore, typically, the spectrometer apparatus may further include at least one wavelength-selective element. As used herein, the term "wavelength-selective element" is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customary meaning. The term may specifically refer to, but is not limited to, any optical element that interacts with different spectral portions of incident light in different ways, such as by having at least one wavelength-dependent optical property (e.g., at least one wavelength-dependent optical property selected from the list consisting of reflectivity, reflection direction, refraction, refraction direction, absorption, transmission, and refractive index).

[0083] The wavelength selection by the at least one wavelength selective element can be performed in at least one beam path of the illumination light, thereby selecting and / or modifying the illumination wavelength of the object, and / or in the detection beam path of the detection light, thereby selecting and / or modifying the detection wavelength, for example, generally for the detector and / or for each photosensitive element. Thus, as an example, the at least one wavelength selective element can include at least one of a wavelength selective element arranged in the beam path of the illumination light and a wavelength selective element arranged in the beam path of the detection light.

[0084] The wavelength-selective element can be selected from the group consisting of a tunable wavelength-selective element and a wavelength-selective element with a fixed transmission spectrum. By way of example, by using a tunable wavelength-selective element, different wavelength ranges can be selected sequentially, whereas by using a wavelength-selective element with a fixed transmission spectrum, the selection of a wavelength range can be fixed but can depend, for example, on the detection position, thereby allowing, for example, different detectors and / or different photosensitive elements of a detector to be simultaneously exposed to light of different spectral ranges in the beam path of the detection light.

[0085] Thus, as outlined above and by way of example, the at least one wavelength-selective element can include at least one of a filter, a grating, a prism, a plasmonic filter, a diffractive optical element, and a metamaterial. More specifically, the spectrometer device can include at least one filter element disposed in the beam path of the light from the object (i.e., disposed in the beam path of the detection light), wherein the filter element can be configured such that each photosensitive element is exposed to a separate spectral range of the light from the object. By way of example, a variable filter element can be used whose transmission depends on its position on the filter element, such that when the variable filter element is placed on top of an array of photosensitive elements, each photosensitive element is exposed to a different spectral range of the incident light (in particular, the detection light from the object). Additionally or alternatively, the at least one wavelength-selective element can include at least one of the following: an array of individual bandpass filters, a patterned filter array, a MEMS interferometer, or a MEMS Fabry-Perot interferometer. Other elements are also possible.

[0086] The evaluation unit can be configured to determine wavelength correction information by considering an emission spectrum of the at least one light source. The term "emission spectrum of the at least one light source" (sometimes also referred to as "center wavelength") is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a special or customary meaning. The term may specifically, but is not limited to, refer to a spectrum affected by the illumination light, specifically a spectrum generated by the illumination light, particularly through interaction with an object and / or a reference target. Alternatively or additionally, the term refers to the spectrum of the illumination light.

[0087] The evaluation unit is configured to determine wavelength correction information by using the emission peak position of at least one emission band in the power spectral density distribution of the wavelengths of light generated by the light source. An emission band is a characteristic that is specific and / or unique to the secondary light generated by the phosphor material. The term "emission peak position" (sometimes also referred to as "center wavelength") is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a specific or customary meaning. The term may specifically refer to, but is not limited to, the frequency and / or wavelength at which the corresponding characteristic exhibits the highest power spectral density. The light generated by the light source may be illumination light or additional light generated by the illumination light, such as detection light or light from a reference target. To generate detection light, the illumination light may interact with an object such that detection light from the object can radiate from the object. To generate light from a reference target, the illumination light may interact with a reference target such that light from the object can radiate from the reference target. The additional light may include information about the illumination light (particularly the characteristic position and / or emission peak position), which may be obtained by evaluating spectral information provided by the additional light. An "emission band" may be a characteristic of light conversion, wherein "primary light" generated by a primary light source, such as at least one light emitting diode, may subsequently be converted into "secondary light" by one or more phosphor materials.

[0088] The emission peak position of at least one emission band in the power spectral density distribution of the wavelength of light used to determine wavelength correction information can be used to calibrate the wavelength of the spectroscopic information. The term "calibrating the wavelength of the spectroscopic information" is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a specific or customary meaning. The term may specifically, but not limited to, use wavelength correction information when obtaining spectroscopic information about an object at least once, thereby subsequently comparing the corrected spectroscopic information with spectroscopic information obtained under standardized conditions. The wavelength correction information can be used to correct the wavelength information of the spectroscopic information about the object. Thus, the intensity derived from at least one detector signal generated by the detected light can be assigned to a corrected wavelength or a corrected wavelength range. Thus, by using the wavelength correction information, at least one wavelength or at least one wavelength range assigned to at least a portion of at least one detector signal (such as a detector signal generated by a specific detector or a specific radiation-sensitive component of a detector, particularly a specific photosensor) can be corrected. Specifically, by considering the wavelength correction information, at least one wavelength or at least one wavelength range assigned to a detector or a photosensor of a detector can be assigned to at least one corrected wavelength or at least one corrected wavelength range.

[0089] The emission peak position of at least one emission band in the power spectral density distribution of the wavelength of light used to determine wavelength correction information can be independent of the temperature of the light source. The term "independent of the temperature of the light source" is a broad term and is to be given its ordinary and conventional meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term can specifically refer to, but is not limited to, a shift in the wavelength of the emission peak position by a maximum of 0.1% / K, preferably 0.01% / K, and more preferably 0.001% / K within a temperature range of -20°C to 85°C, preferably -5°C to 80°C, and more preferably 0°C to 75°C.

[0090] At least one evaluation unit can be configured to determine wavelength correction information on-site online. As used herein, the term "online" is a broad term and is to be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or customized meaning. The term can specifically refer to, but is not limited to, the following characteristics: a process is performed while another process is in progress (such as being performed during the other process) and preferably does not have to be started or initiated separately by a user. Therefore, in particular, determining the correction from at least one wavelength by taking into account the wavelength correction information can be performed as an online calibration without the need to use an external setting to perform the calibration. Further, in particular, the detector signal can be corrected by using the at least one wavelength correction information during the acquisition of spectroscopic information about at least one object.

[0091] The at least one detector may be configured to generate at least one detector signal by detecting at least one of:

[0092] Illuminating light from a light source,

[0093] detection light from the subject; or

[0094] light from at least one reference target;

[0095] The evaluation unit can be configured to determine wavelength correction information, in particular, wavelength correction information determined based on the emission peak position of at least one emission band in the power spectral density distribution of the wavelength of the corresponding detected light. Thus, the detected illumination light can specifically have a spectrum that is unaffected by the object and / or reference target. As used herein, the term "light from at least one reference target" is a broad term and is to be given its ordinary and conventional meaning for those skilled in the art and is not limited to a specific or customary meaning. The term can specifically, but not be limited to, light propagating from the reference target to the spectrometer device, or more specifically, to a detector of the spectrometer device, such as diffusely reflected light. The detection light can include at least one of the following: illumination light reflected by the reference target, illumination light scattered by the reference target, illumination light transmitted by the reference target, or luminescence light generated by the reference target (e.g., phosphorescence or fluorescence generated by the reference target after optical, electrical, or acoustic excitation of the reference target by the illumination light, etc.). The reference target can have a known effect on the spectrum of the illumination light. The reference target can include a material that has a known optical effect on the detected light from the reference target. Such a material can be, for example, barium sulfate. Other materials may also be present.

[0096] At least one detector signal evaluated to obtain spectroscopic information about the object may include wavelength correction information. Before obtaining the spectroscopic information about the object, the emission peak position of at least one emission band in the power spectral density distribution of the wavelength of the corresponding detected light may be detected by the at least one detector.

[0097] The spectrometer device may further comprise at least one measuring unit for generating at least one information item about at least one electrically measurable quantity required to drive the light-emitting diode (in particular, a forward voltage), and the evaluation unit may be further configured to take this information item about the at least one electrically measurable quantity into account when deriving the spectroscopic information from the detector signal. This allows correction of at least one intensity of the spectroscopic information.

[0098] As used herein, the term "measuring unit" is a broad term and is to be given its ordinary and customary meaning for a person of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically, but not limited to, any device or combination of devices configured to measure one or more electrical parameters of the electrical power supplied to a light source (particularly to at least one light-emitting diode) and to generate at least one item of information about an electrically measurable quantity (particularly a forward voltage). The measuring unit may be an element of a drive unit and / or an evaluation unit.

[0099] As used herein, the term "electrically measurable quantity" is a broad term and is to be given its ordinary and customary meaning to those skilled in the art and is not limited to a special or customary meaning. The term specifically refers to, but is not limited to, any parameter required to drive a light-emitting diode and that can be electrically measured. For example, the electrically measurable quantity may be at least one quantity selected from the group consisting of: forward voltage; input power; current; resistance, inductance, capacitance, etc.

[0100] As used herein, the term "forward voltage" is a broad term and is to be given its ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically, but is not limited to, refer to a voltage to be applied to an LED in the forward direction, i.e., by applying the positive contact of a voltage or current source to the p-layer of the LED and the negative contact to the n-layer of the LED, in order to generate a predetermined current through the LED. By way of example, the predetermined current defining the forward voltage may be a current known to generate a predetermined light output of the light source and / or light-emitting diode. The predetermined current may specifically be in the range of 10 mA to 500 mA, more specifically in the range of 100 mA to 300 mA. Additionally or alternatively, the term "forward voltage" may refer to the minimum voltage to be applied to an LED in the forward direction in order to generate a significant current through the LED, specifically a predetermined current defined as a minimum current, such as a current reaching and / or exceeding a minimum threshold. By way of example, the forward voltage may be a voltage that can be derived from the diode characteristics of an LED (i.e., from a graph indicating current as a function of voltage applied to the LED). As an example, the forward voltage can be obtained from a logarithmic plot of the diode characteristic of the LED, for example, by determining the inflection point in the forward branch of the characteristic, and / or by determining the voltage at the intersection of a straight line representing the steep portion of the forward branch with the horizontal or voltage axis. Thus, the forward voltage can generally represent the voltage that would be applied to the LED in the forward direction (p to n) in order to drive current through the diode. The forward voltage can depend on the band gap of the LED. Thus, in general, LEDs having a primary emission wavelength or range of primary emission wavelengths in the short wavelength range (such as in the blue spectrum) may typically require a higher forward voltage than LEDs emitting light in the longer wavelength range (such as red light). The forward voltage is sometimes also referred to as the "forward bias" or "junction voltage". For the forward voltage, the symbol or .

[0101] Thus, in general, the direction of current through an LED where the current flows from the p-doped layer to the n-doped layer of the LED, and / or the direction of current where the p-side or p-doped layer of the LED is connected to the positive connector of a power supply and where the n-side or n-doped layer of the LED is connected to the negative connector of the power supply can be identified as the "forward direction".

[0102] To generate at least one item of information about at least one electrically measurable quantity (particularly forward voltage) required to drive a light-emitting diode (e.g., driving the LED in the forward direction with a predetermined current), a measurement unit (e.g., as part of a driver unit) may include one or more measuring devices or measuring elements, such as one or more voltage measuring devices. By way of example, the at least one item of information about the at least one electrically measurable quantity (particularly forward voltage) may be provided by the measurement unit in the form of at least one electrical signal and / or electrical information, which may include, for example, one or both of an analog signal and a digital signal. The electrical signal including the at least one item of information about the at least one electrically measurable quantity (particularly forward voltage) may be provided directly or indirectly to an evaluation unit. The electrical signal may be time-dependent or static.

[0103] In another aspect, a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object is disclosed. The method comprises the following steps, which may be performed in a given order. However, different orders are also possible. In particular, one, more than one, or even 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 timely overlapping manner, or even in parallel, and / or in combination. The method may further include additional method steps not listed.

[0104] The method comprises the following steps:

[0105] a. electrically driving at least one light source by using at least one driving unit (138), the light source comprising at least one light-emitting diode and at least one luminescent material for light-converting primary light generated by the light-emitting diode;

[0106] b. detecting light using at least one detector and thereby generating at least one detector signal; and

[0107] c. evaluating at least one detector signal generated by a detector using at least one evaluation unit, and determining wavelength correction information by using, in particular, characteristic positions in a power spectral density distribution of the wavelengths of light generated by the light source, in particular emission peak positions of at least one emission band, and determining wavelength correction information by using emission peak positions of at least one emission band in a power spectral density distribution of the wavelengths of light generated by the light source, wherein the luminescent material is a phosphor, and wherein the emission band is a characteristic of secondary light generated by the material of the phosphor.

[0108] The emission peak position of at least one emission band in the power spectral density distribution of the wavelengths of light (particularly detected by at least one detector) can be independent of the temperature of the light source. The detected power spectral density distribution of the wavelengths of light can be determined using at least one detector.

[0109] On the other hand, a method for obtaining spectroscopic information about at least one object is disclosed. The method includes the following steps that can be performed in a given order. However, different orders are also possible. In particular, one, more than one, or even all method steps can be performed once or repeatedly. Further, these method steps can be performed sequentially, or alternatively, one or more method steps can be performed in a timely overlapping manner or even in a parallel manner and / or in a combined manner. The method may further include additional method steps that are not listed.

[0110] The method comprises the following steps:

[0111] 1. electrically driving at least one light source by using at least one driving unit, the light source comprising at least one light-emitting diode and at least one luminescent material for light-converting primary light generated by the light-emitting diode;

[0112] 2. Illuminating the object with illumination light generated by the light source;

[0113] 3. detecting light using at least one detector and thereby generating at least one detector signal; and

[0114] 4. Evaluating at least one detector signal using at least one evaluation unit and deriving spectroscopic information about the object from the at least one detector signal using the evaluation unit, wherein the spectroscopic information about the object is derived by taking into account wavelength correction information, in particular, derived from the at least one detector signal.

[0115] The wavelength correction information can be determined using a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object. This method can further include the step of generating at least one item of information about at least one electrically measurable quantity required to drive a light-emitting diode using at least one measurement unit; the item of information about the at least one electrically measurable quantity (particularly the forward voltage) can be taken into account when deriving the spectroscopic information from the detector signal. In particular, any of the above methods can be performed in-situ.

[0116] As further outlined above, any of the methods described above and / or according to any of the embodiments described in further detail below can be at least one of computer-controlled, computer-implemented, and computer-assisted, in whole or in part, for example, by using one or more computer programs running on at least one processor (e.g., at least one processor of a spectrometer device (e.g., at least one processor integrated within a detector and / or within an evaluation unit)). Specifically, as outlined above, at least one step of any of the methods involving the use of an evaluation unit can be at least one of computer-controlled, computer-implemented, and computer-assisted. However, it should be noted that other steps of the method can also be at least one of computer-controlled, computer-implemented, and computer-assisted, in whole or in part, such as one or more of steps a., b., and c. of the method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object and / or one or more of steps 1., 2., 3., and 4. of the method for obtaining spectroscopic information about at least one object.

[0117] In another aspect, a computer program is disclosed. The computer program includes instructions that, when executed by an evaluation unit of a spectrometer device, cause the evaluation unit to perform any of the methods described elsewhere herein. In another aspect, a non-transitory computer-readable storage medium is disclosed. The non-transitory computer-readable storage medium includes instructions that, when executed by the evaluation unit of a spectrometer device, cause the evaluation unit to perform any of the methods described elsewhere herein.

[0118] As used herein, the terms "computer-readable data carrier," "computer-readable storage medium," and "non-transitory computer-readable medium" are broad terms and are to be given their ordinary and customary meanings to those skilled in the art and are not limited to special or customized meanings. These terms may specifically refer to, but are not limited to, data storage devices, particularly non-transitory data storage devices, such as hardware storage media having computer-executable instructions stored thereon. A computer-readable data carrier or storage medium or computer-readable medium may specifically be or include a storage medium such as a random access memory (RAM) and / or a read-only memory (ROM).

[0119] As used herein, the terms "having," "including," or "comprising," or any grammatical variations thereof, are used in a non-exclusive manner. Thus, these terms can refer to the absence of additional features in the entity described in that context, in addition to the features introduced by these terms, or the presence of one or more additional features. By way of example, the expressions "A has B," "A includes B," and "A contains B" can refer to the absence of any other elements in A besides B (i.e., A consists solely and solely of B), or the presence of one or more additional elements in entity A, such as element C, elements C and D, or even additional elements, in addition to B.

[0120] Furthermore, it should be noted that the terms "at least one", "one or more", or similar expressions indicating that a feature or element may occur once or more than once are typically used only once when introducing the corresponding feature or element. In most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" is not repeated, although the corresponding feature or element may in fact occur once or more than once.

[0121] Further, as used herein, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features, without limiting the possibilities of alternatives. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As the skilled person will recognize, the present invention can be carried out through the use of alternative features. Similarly, features introduced by "in an embodiment of the invention" or similar expressions are intended to be optional features, without any limitation on alternative embodiments of the invention, without any limitation on the scope of the invention, and without any limitation on the possibility of combining features introduced in this manner with other optional or non-optional features of the invention.

[0122] In one or more of the above-described embodiments and / or in one or more of the embodiments described in further detail below, the spectrometer apparatus and method according to the present invention offer numerous advantages over known apparatus and methods of similar types. Specifically, online calibration or correction can be performed. More specifically, wavelength correction information can provide reliable correction parameters, which typically vary with aging of at least some components of the spectrometer apparatus, for deriving a spectrum or spectral information about an object.

[0123] Although the spectrum of a light source (particularly a light-emitting diode) can be temperature-dependent, the position of its emission band can be stable over a wide temperature range. Therefore, the light source can serve as an ideal reference for deriving wavelength correction information provided by the spectrometer itself. Reference measurements performed using the spectrometer can be applied at any time, and the spectrometer can be recalibrated using the wavelength correction information. This ensures that the wavelength information included in the spectroscopic information about the object is accurate. The wavelength correction information can be determined independently of the light source temperature, which may not affect the calibration.

[0124] Furthermore, the use of phosphor LEDs instead of or in addition to conventional thermal emitters (such as incandescent lamps with a tungsten filament as light source) can provide several advantages. Thus, in general, even though thermal emitters can provide a flat spectrum, low temperature dependence and a high power spectral density even at long wavelengths (such as in the NIR range), thermal emitters are generally not well suited for high-volume spectrometer production. Thus, in general, disadvantages of thermal emitters include high complexity of the manufacturing process, low conversion efficiency of electrical power to optical power and physical limitations of miniaturization. These disadvantages can be overcome by using LEDs, in particular phosphor LEDs. LEDs have proven to be reliable light sources, such as standardized light sources in visible light schemes.

[0125] In the context of the present invention, a broadband light source can be provided by using one or more phosphor LEDs in a spectrometer device, the one or more phosphor LEDs comprising at least one light-emitting diode and at least one luminescent material or phosphor. Thus, as an example, a white light source and / or a broadband light source in the infrared range, in particular in the NIR range, can be generated. The phosphor can convert photons with a shorter wavelength and therefore higher energy into photons with a longer wavelength or lower energy, for example by transferring a portion of the primary photon energy to the phosphor material, such as to the phosphor lattice. The remaining lower energy can result in the emission of long-wavelength photons.

[0126] Thus, a luminescent material can be configured to absorb one or more primary photons generated by a light-emitting diode and, in response to such absorption, emit one or more secondary photons. The emission of the secondary photons can occur instantaneously or after a delay or decay time. Thus, as outlined above, the luminescent material can be or include at least one of a phosphorescent material and a fluorescent material. The phenomenon of phosphorescence can result in the emission of secondary light (e.g., long-wavelength light) from the luminescent material within a characteristic lifetime, τ (tau), after the primary light (e.g., short-wavelength or high-energy pump light) is turned off, for example, due to a forbidden quantum optical transition or a forbidden dipole transition. Specifically, in a luminescent material, the emission of secondary light can occur via forbidden transitions (e.g., forbidden dipole transitions) that have a longer lifetime than, for example, transitions allowed by spontaneous dipoles, as can be the case with many fluorescent materials.

[0127] In particular, as outlined above, a luminescent material, in particular a phosphorescent material, can be used that has absorption in the blue spectral range and emission in the infrared spectral range. By way of example, a luminescent material can be used that is capable of converting blue primary light or pump light having a wavelength of, for example, 440 nm into near-infrared secondary light, for example, secondary light having a wavelength in the range of 1 to 3 µm, preferably 1.3 to 2.5 µm, and more preferably 1.5 to 2.2 µm. Additionally or alternatively, the primary light or pump light can be generated by an infrared LED having a wavelength in the range of 850 nm to 940 nm, which can then be converted by the luminescent material into near-infrared secondary light having a wavelength in the range of 1 to 3 µm, preferably 1.3 to 2.5 µm, and more preferably 1.5 to 2.2 µm.

[0128] A phosphor LED comprising at least one light emitting diode and at least one luminescent material may be implemented as a single component. Thus, on a technical level, a phosphor LED may comprise a plurality of subcomponents.

[0129] First, a phosphor LED may include one or more functional components, such as an LED die, including at least one junction, such as at least one pn junction, between at least two semiconductor regions. In the LED die, primary light, such as short-wavelength pump light, may be generated, for example, in the blue spectral range.

[0130] Further, a phosphor LED may include at least one luminescent material, in particular at least one phosphor material, which may in particular be placed directly on top of the LED die and may convert primary light, in particular pump light, into secondary light, in particular into long wavelength near-infrared light.

[0131] Furthermore, the phosphor LED may comprise one or more substrates, in particular one or more electrically insulating substrates. Thus, as an example, the phosphor LED may comprise one or more ceramic substrates. The at least one substrate may be configured to hold at least one LED die and at least one luminescent material. Furthermore, the at least one substrate may hold or comprise one or more electrical connection components, such as one or more contact pads and / or one or more electrical leads, such as one or more metal contacts and / or one or more metal leads. In addition, the substrate (such as a ceramic substrate) may be configured to act as a heat sink. For example, during the conversion process, heat may be generated in both the LED die and the luminescent material (such as due to the limited conversion of electrical energy into photon energy), as well as in the luminescent material. The heat may be dissipated in the substrate, such as in the ceramic substrate.

[0132] Spectrometer devices using at least one LED can be configured to apply a continuous wave (CW) mode and / or preferably at least one modulated drive scheme to improve measurement accuracy and reliability. Thus, for example, at least one driver unit can be configured to apply a modulated drive scheme to the LED, and the evaluation device can be configured to utilize the modulated drive scheme to derive at least one item of spectroscopic information from at least one detector signal. For example, phase-locking techniques, filtering techniques, etc., as known to those skilled in the art, can be applied.

[0133] Thus, the spectrometer apparatus may be configured to apply a modulated drive scheme to the LEDs to compensate for the detector's DC background and / or reduce detector noise.Thus, as an example, a bandpass filter may be applied to the detector signal in order to remove the DC component.

[0134] Illumination light generated by a light source (specifically, a phosphor LED) can be directed to illuminate the sample. For example, one or more mirrors can be used to direct the illumination light. Detection 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, such as one or more dispersive elements, can be used to separate the detection light into its spectral components.

[0135] One or more detector signals can be recorded by the detector, for example, using readout electronics included in the spectrometer device. Specifically, the readout electronics can be included in one or both of the detector and the evaluation device. For example, the readout electronics can include one or more signal processing devices. Thus, as outlined above, for evaluation by the evaluation device, a "raw" detector signal and / or one or more secondary detector signals derived therefrom (e.g., one or more filtered detector signals) can be used. Furthermore, at least one detector signal (primary or secondary) can be combined with additional information (e.g., information about the wavelength), such as the number of the photosensor element in the photosensor array from which the detector signal was derived, which is known to have been exposed to a specific wavelength within a certain wavelength range. In the context of the present invention, specifically in the context of evaluating detector signals by an evaluation unit, the option of evaluating the raw detector signal and / or the option of evaluating the secondary detector signal (e.g., a preprocessed detector signal, a processed detector signal, or a combined detector signal) is possible. However, the present invention remains relevant, in particular, for correcting the "raw" detector signal (specifically, a detector signal indicating a variation in signal intensity with the detection wavelength). However, other options are possible.

[0136] As an example, the detector signal (e.g., by the detector itself and / or by the evaluation unit) can be processed or preprocessed into a secondary detector signal by applying one or more Fourier transforms. For example, a fast Fourier transform can be applied. Based on the processed secondary detector signal, at least one item of spectroscopic information can be derived, for example, by software executed by the evaluation unit. Thus, as an example, the Fourier transform of the detector signal can be read out by software of the spectroscopic device (specifically, the evaluation device) and post-processed into spectroscopic information about the object.

[0137] As outlined above, LEDs and phosphor LEDs can thus provide highly efficient light sources that can be modulated to implement specific evaluation scenarios and to reduce noise and artifacts. By further using at least one item of information regarding an electrically measurable quantity (particularly the forward voltage) as a correction or calibration parameter, temperature variations within the light source (particularly within the LED) can be fully or partially compensated. Therefore, for a typical LED as used herein, when operated at the maximum voltage and current the LED can withstand, the temperature of various components of the light source (particularly the LED) can vary over a wide temperature range. As an example, the standard operating current can range from 2 mA to 1000 mA, typically from 10 mA to 300 mA. As an example, the forward voltage can range from 1.5 V to 3.5 V, typically from 2.25 V to 3 V. Thus, as an example, under maximum operating conditions, the emitter junction temperature can be 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. According to the ANSI / ESDA / JEDEC JS-001-2012 standard, the ESD sensitivity of an LED can be 250 V. These typical parameters show a large temperature variation range, which may have an impact on the spectroscopic information obtained about the object by the spectrometer device. It should be noted that other parameters and other parameter ranges are also possible.

[0138] It is generally known that phosphor LEDs generate different spectra depending on the composition of the luminescent material (such as the phosphor). Typically, each phosphor LED has multiple peaks in its spectrum, which is typically distributed over a wide wavelength range. However, even when the same current is supplied to the phosphor LED, the spectral characteristics or spectrum may vary with temperature. These variations can include shifts in emission peaks, broadening or narrowing of the spectrum, increases or decreases in emission, and so on. However, in many cases, emission at some wavelengths is more significantly affected than at others. Therefore, within the spectrum, there is typically a specific central wavelength where the power (specifically, the power spectral density) generally does not vary with temperature. Therefore, each wavelength typically has its own temperature coefficient with respect to power increase / decrement. Consequently, the shape of the spectrum varies with temperature. By using electrically measurable quantities (particularly forward voltage) as correction parameters, individual temperature corrections can be performed on the spectra at different wavelengths. Therefore, as outlined above, the evaluation unit can be configured to individually correct the detector signals in different spectral ranges and to combine these individually corrected detector signals to obtain spectroscopic information. More specifically, as also outlined above, such individual calibration can be performed by using an array of photosensitive elements, wherein each photosensitive element can be configured to generate at least one detector signal, and wherein each detector signal can be individually calibrated using an electrically measurable quantity (particularly forward voltage) as a calibration parameter. Finally, the calibrated detector signals can be combined to obtain spectroscopic information.

[0139] By using electrically measurable quantities (particularly forward voltage) as correction parameters, it is possible to correct for temperature variations and individual characteristics of phosphor LEDs. Thus, as an example, when the same current is applied to the LED, the forward voltage of the LED will generally decrease as the temperature increases. Each type of LED has its own forward voltage-temperature characteristic curve. In general, the forward voltage of an LED decreases linearly with increasing temperature, such as with to Slope in the range of V / K.

[0140] Furthermore, the spectrometer apparatus and method can take into account the characteristics of the luminescent materials used in the light source. Thus, as outlined 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 can be characterized by a so-called "characteristic time constant" τ (also known as "time constant," "decay time," or "saturation time"). As is well known to those skilled in the art, the term "time constant" is a broad term and is to be given its ordinary and customary meaning for those skilled in the art and is not limited to a specific or customary meaning. When used in the context of processes where the rate or probability of a process (such as photon emission) is proportional to the population of one or more states or process states, this population typically varies exponentially. In these processes, the time constant τ can determine the 1 / e time of the process. For luminescent materials or converters, particularly phosphors, two different time constants can occur. First, the first time constant can describe the typical time for emission of the converted light to reach saturation. Second, the second time constant can describe the typical duration of the afterglow of the luminescent material or converter.

[0141] Typical time constants for phosphor converters are in the range of 0.1 ms to < 10 ms. These time constants often vary between different phosphor LEDs and / or between different types of luminescent materials or phosphors. Typically, phosphors emitting at shorter wavelengths exhibit shorter time constants. Additionally, the decay constant and the growth constant Can depend on wavelength. The time constant is usually extracted from the step response of the optical signal by applying / cutting off the forward current.

[0142] After the forward current is turned off, the signal or emission typically decays according to equation (1):

[0143] (1)

[0144] After the forward current is turned on, the signal or emission generally increases according to equation (2):

[0145] (2)

[0146] For equations (1) and (2), When the forward current is applied / cut off, The optical signal level at . for The optical signal level reached when

[0147] Another characteristic of LEDs is that their light output power varies with forward current. Therefore, generally, increasing the input current increases the LED's permissible power. The shape (e.g., slope) of the light output vs. forward current curve is characteristic of each LED.

[0148] As outlined above, the use of electrically measurable quantities, in particular the forward voltage, as control or correction parameters for spectroscopic analysis purposes allows for efficient and reliable online correction or online calibration. Thereby, various challenges of typical spectrometers and their corresponding calibrations can be overcome. In particular, in a typical spectroscopic analysis process, a reference measurement of the spectrometer allows for calibration of the instrument response, so that the measurement only provides information about the sample. However, if the optical components of the spectrometer apparatus change between the reference measurement and the sample measurement, the sample information is affected by the systematic changes and thus the information about the sample may be distorted. In particular, when the spectrum of the light source is In a reference measurement (during which the light source has a spectrum ) and the actual sample measurement (during which the light source has a spectrum ) between the two spectra, the spectroscopic information about the image or sample will be distorted because the spectrum is usually based on two spectra. 、 The situation is often even more complex in phosphor LEDs, as the spectrum of a phosphor LED is a combination of the spectrum of the LED and the spectrum of the luminescent material. Both components of a phosphor LED can be affected by temperature changes in different ways. Therefore, for phosphor LEDs, the spectrum can usually be described by equation (3):

[0149] (3)

[0150] in, Express the spectrum of the light source LS as wavelength , LED pn junction temperature and the temperature of the phosphor function. represents the spectrum of an LED (e.g. a blue LED), and Represents the spectrum of a luminescent material, such as a phosphor.

[0151] Both subcomponents, the LED and the luminescent material, exhibit separate temperature responses. Therefore, system temperature variations or offsets, or ambient temperature variations or offsets (particularly between reference and sample measurements), typically affect the spectrum by affecting both the LED junction and the luminescent material.

[0152] At least one item of information about an electrically measurable quantity (in particular the forward voltage), such as the forward voltage itself and / or at least one other item of information derived directly or indirectly from the forward voltage (for example a pre-processed forward voltage measurement value), or another electrically measurable quantity required for driving the light-emitting diode (such as feed-in power, current, resistance, inductance, capacitance, etc.) provides a reliable correction parameter. By taking into account at least one item of information about the electrically measurable quantity (in particular the forward voltage) when deriving the spectroscopic information from the detector signal, various temperature changes can be taken into account. Thus, a self-referencing scheme can be applied, in which internal parameters, i.e. information items about the electrically measurable quantity (in particular the forward voltage), can be used for reference, in particular online reference. This will be outlined in the following in an exemplary manner, using the forward voltage as an example of an electrically measurable quantity required for driving the light-emitting diode. Without wishing to be bound by this theory, this is because at the temperature of the luminescent material the temperature of the luminescent material is affected by the temperature of the luminescent material. The temperature of the LED pn junction There are fixed dependencies between:

[0153] (4)

[0154] Furthermore, the forward voltage and the temperature of the pn junction There are fixed dependencies between:

[0155] (5)

[0156] By using these dependencies, a model can be created that takes into account the entire light source, based only on the junction temperature Rather than being based on a combination of junction temperature and phosphor temperature. is the forward voltage Therefore, the emission spectrum of the light source can be described by the following formula:

[0157] (6)

[0158] The emission spectrum of the light source is therefore a function of wavelength and forward voltage. This function can be determined, for example, empirically, semi-empirically, or even theoretically. This function can be determined in one or more calibration processes by determining the forward voltage and, for example, the intensity as a function of wavelength. From this, one or more calibration curves can be determined, and these one or more calibration curves can be taken into account in the evaluation step. Thus, by measuring the forward voltage for a reference measurement or a sample measurement or during a measurement, the influence of temperature can be effectively corrected.

[0159] As an example, as outlined above, the emission spectrum of the light source before or after interaction with the object can be described as a function of the forward voltage, as outlined in equation (6) above. In order to correct the emission spectrum, as an example, the emission spectrum can be calculated based on at least one reference forward voltage. To correct the emission spectrum. As an example, the reference forward voltage can be a forward voltage that is expected or measured at a specific reference temperature (such as room temperature). Additionally or alternatively, forward voltages at one or more other reference temperatures (such as case temperature, heat sink temperature, or any other system-specific temperature) can be used.

[0160] For the correction, use at least one forward voltage-dependent correction factor or correction function :

[0161] (7)

[0162] As indicated, the correction function Can be wavelength and forward voltage The correction function may be determined by one or more calibration measurements (e.g., by factory calibration). As an example, the calibration measurements may imply that, for a plurality of different wavelengths and / or a plurality of different wavelength ranges, at each forward voltage, the corresponding signal varies with the measured forward voltage. As an example, based on experimental data, for each wavelength or wavelength range, one or more correction factors may be derived, which describe the correction as a function of the forward voltage, e.g., by fitting a correction curve to the experimental data and / or by generating a model for the dependence of the signal on the forward voltage. Thus, as an example, an analytical model, an empirical model, or a semi-empirical model may typically be used for the correction. Examples will be given in further detail below.

[0163] Therefore, the correction, correction factor or correction function Usually, the analysis model can be based on the dependency The analytical model can be determined (e.g., calculated) for a specific phosphor LED during a factory calibration process or a field calibration process, for example, under controlled environmental conditions (e.g., a known temperature). Additionally or alternatively, batch calibration can be performed. Thus, for a batch of phosphor LEDs, a model, such as an analytical model, can be derived from independent measurements of representative devices. This approach can also be referred to as "gold standard" calibration.

[0164] As an example and as outlined above, the calibration factor may correct the spectrum to correspond to some reference, such as to a reference forward voltage , for example a reference forward voltage measured at a reference temperature. As outlined above, the model can be derived from the calibration data , for example by fitting a reference curve to experimental data showing, for example, how the signal at a particular wavelength varies with the measured forward voltage for various wavelengths. As an example, the correction factor or correction function can be obtained according to equation (8) :

[0165] (8)

[0166] Therefore, in subsequent measurements, the detector signal can be corrected by comparing it with a correction factor or correction function The detector signal is corrected, for example, for each wavelength, by multiplication, thereby generating detector signals which are largely independent of the actual temperature at the respective location of the spectrometer device and which, further, are largely unaffected by temperature drifts and the like.

[0167] In summary, and without excluding further possible embodiments, the following embodiments may be envisaged:

[0168] Embodiment 1: A spectrometer device for obtaining spectroscopic information about at least one object, the spectrometer device comprising:

[0169] i. at least one light source for generating illumination light for illuminating an object, the light source comprising at least one light-emitting diode and at least one luminescent material for light conversion of the primary light generated by the light-emitting diode;

[0170] ii. at least one detector for detecting light and thereby generating at least one detector signal;

[0171] iii. At least one evaluation unit configured to derive the spectroscopic information about the object from at least one detector signal, wherein the evaluation unit is configured to derive the spectroscopic information about the object by taking into account wavelength correction information, in particular, derived from the at least one detector signal.

[0172] Embodiment 2: The spectrometer device according to the preceding embodiment, wherein the light-emitting diode has a primary emission range at least partially in the spectral range of 420 nm to 460 nm, more particularly in the range of 440 nm to 455 nm, more particularly at 440 nm.

[0173] Embodiment 3: The spectrometer device according to any one of the preceding embodiments, wherein the luminescent material is a phosphor.

[0174] Embodiment 4: The spectrometer device according to any of the preceding embodiments, wherein the illumination light has a spectral range that lies at least partially in the near infrared spectral range, in particular in the spectral range of 1 to 3 µm, preferably 1.3 to 2.5 µm, more preferably 1.5 to 2.2 µm.

[0175] Embodiment 5: The spectrometer device according to any of the preceding embodiments, wherein the detector is configured to generate detector signals for at least two different spectral ranges of light from the object, specifically in a manner of at least one of sequential generation and simultaneous generation, to obtain the spectroscopic information.

[0176] Embodiment 6: The spectrometer device according to any one of the preceding embodiments, wherein the detector comprises an array of photosensitive elements, wherein each photosensitive element is configured to generate at least one detector signal to obtain spectroscopic information.

[0177] Embodiment 7: The spectrometer device according to any one of the preceding embodiments, wherein the spectrometer device is configured such that the light sensitive elements are sensitive to different spectral ranges of light from the object.

[0178] Embodiment 8: The spectrometer device according to any of the preceding embodiments, wherein the spectrometer device comprises at least one filter element arranged in the beam path of the light from the object, wherein the filter element is configured such that each photosensitive element is exposed to a separate spectral range of the light from the object.

[0179] Embodiment 9: According to the spectrometer device described in any one of the preceding embodiments, the spectrometer device further comprises at least one wavelength selection element, the wavelength selection element comprising at least one of a wavelength selection element arranged in the beam path of the illumination light and a wavelength selection element arranged in the beam path of the detection light.

[0180] Embodiment 10: The spectrometer device according to any one of the preceding embodiments, wherein the wavelength selective element is selected from the group consisting of a tunable wavelength selective element and a wavelength selective element with a fixed transmission spectrum.

[0181] Embodiment 11: The spectrometer device according to any one of the preceding embodiments, wherein the evaluation unit is configured to determine the wavelength correction information by taking into account an emission spectrum of the at least one light source.

[0182] Embodiment 12: The spectrometer device according to any one of the preceding embodiments, wherein the evaluation unit is configured to determine the wavelength correction information by using an emission peak position of at least one emission band in a power spectral density distribution of wavelengths of light generated by the light source.

[0183] Embodiment 13: The spectrometer device according to any one of the preceding embodiments, wherein the emission position of at least one emission band in the power spectral density distribution of the wavelength of light used to determine the wavelength correction information is used to calibrate the wavelength of the spectroscopic information.

[0184] Embodiment 14: The spectrometer device according to any one of the preceding embodiments, wherein the emission peak position of at least one emission band in the power spectral density distribution of the wavelength of light used to determine the wavelength correction information is independent of the temperature of the light source.

[0185] Embodiment 15: The spectrometer device according to any one of the preceding embodiments, wherein the at least one evaluation unit is configured to determine the wavelength correction information on-site.

[0186] Embodiment 16: The spectrometer apparatus according to any one of the preceding embodiments, wherein the at least one detector is configured to generate the at least one detector signal by detecting at least one of:

[0187] The illumination light from the light source,

[0188] detection light from the object; or

[0189] light from at least one reference target;

[0190] The evaluation unit is configured to determine the wavelength correction information, in particular the wavelength correction information determined based on an emission peak position of at least one emission band in a power spectral density distribution of the wavelength of the corresponding detected light.

[0191] Embodiment 17: The spectrometer device according to any of the preceding embodiments, wherein the at least one detector signal evaluated to obtain the spectroscopic information about the object comprises the wavelength correction information.

[0192] Embodiment 18: The spectrometer device according to any one of the preceding embodiments, wherein, before obtaining the spectroscopic information about the object, the emission peak 193 position of at least one emission band in the power spectral density distribution of the wavelength of the corresponding detected light is detected by the at least one detector.

[0193] Embodiment 19: A spectrometer device according to any of the preceding embodiments, wherein the spectrometer device further comprises at least one measuring unit for generating at least one information item about at least one electrically measurable quantity required to drive the light-emitting diode, wherein the evaluation unit is further configured to take into account the information item about the at least one electrically measurable quantity when deriving the spectroscopic information from the detector signal.

[0194] Embodiment 20: A method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object, the method comprising:

[0195] a. electrically driving at least one light source by using at least one driving unit, the light source comprising at least one light-emitting diode and at least one luminescent material for light conversion of the primary light generated by the light-emitting diode;

[0196] b. detecting light using at least one detector and thereby generating at least one detector signal; and

[0197] c. evaluating the at least one detector signal generated by the detector using at least one evaluation unit, and determining wavelength correction information by using, in particular, characteristic positions in the power spectral density distribution of the wavelengths of the light generated by the light source, more in particular emission peak positions of at least one emission band.

[0198] Embodiment 21: The method according to the preceding embodiment, wherein the emission peak position of at least one emission band in the power spectral density distribution of the wavelength of light is independent of the temperature of the light source.

[0199] Embodiment 22: The method according to any one of the two preceding embodiments, wherein the power spectral density distribution of the wavelengths of the detected light is determined by using the at least one detector.

[0200] Embodiment 23: A method of obtaining spectroscopic information about at least one object, the method comprising:

[0201] 1. electrically driving at least one light source by using at least one driving unit, the light source comprising at least one light-emitting diode and at least one luminescent material for photoconverting primary light generated by the light-emitting diode;

[0202] 2. illuminating the object with illumination light generated by the light source;

[0203] 3. detecting light using at least one detector and thereby generating at least one detector signal; and

[0204] 4. Evaluating the at least one detector signal by using at least one evaluation unit and deriving the spectroscopic information about the object from the at least one detector signal by using the evaluation unit, wherein the spectroscopic information about the object is obtained by taking into account, in particular, wavelength correction information obtained from the at least one detector signal.

[0205] Embodiment 24: The method according to the preceding embodiment, wherein the wavelength correction information is determined by using a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object according to any of the preceding embodiments related to the calibration method.

[0206] Embodiment 25: According to the method described in any one of the two preceding embodiments, the method further comprises the following steps: generating at least one information item about at least one electrically measurable quantity required to drive the light-emitting diode by using at least one measuring unit; wherein, when obtaining the spectroscopic information from the detector signal, the information item about the at least one electrically measurable quantity (in particular the forward voltage) is taken into account.

[0207] Embodiment 26: A computer program comprising instructions which, when executed by an evaluation unit of a spectrometer apparatus according to any one of the preceding embodiments relating to a spectrometer apparatus, cause the evaluation unit to perform a method according to any one of the preceding embodiments relating to a method.

[0208] Embodiment 27: A non-transitory computer-readable storage medium comprising instructions, which, when executed by an evaluation unit of a spectrometer device according to any of the aforementioned embodiments relating to a spectrometer device, causes the evaluation unit to perform any of the methods described in any of the aforementioned embodiments relating to methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0209] Additional optional features and embodiments will be disclosed in more detail in the subsequent embodiments, preferably in conjunction with the dependent claims. As will be appreciated by those skilled in the art, the respective optional features can be implemented independently and in any feasible combination. The scope of the present invention is not limited by the preferred embodiments. The embodiments are schematically depicted in the accompanying drawings. Identical reference numerals in these drawings represent identical or functionally equivalent elements.

[0210] In the attached figure:

[0211] Figure 1 A schematic overview of a spectrometer apparatus is shown;

[0212] Figure 2 shows a schematic cross-sectional view of a light source;

[0213] Figure 3 shows a schematic flow chart illustrating the generation and processing of detector signals;

[0214] Figure 4 shows a graph representing an overlay of infrared radiation spectra of a phosphor LED at various temperatures;

[0215] Figure 5shows a graph representing the variation of transmitted power as a function of temperature for a selected number of wavelengths;

[0216] Figure 6 shows a graph of the forward voltage versus temperature for a selected current;

[0217] Figure 7A and Figure 7B The spectra of two different types of phosphor LEDs are shown;

[0218] Figure 8A and Figure 8B The attenuation constant ( Figure 8A ) and the growth constant ( Figure 8B )

[0219] Figure 9A and Figure 9B The attenuation constant ( Figure 9A ) and the growth constant ( Figure 9B )

[0220] Figure 10 shows a graph representing normalized light output as a function of forward current;

[0221] Figure 11 A method for calibrating a spectrometer device is shown;

[0222] Figure 12 A method of obtaining spectroscopic information about at least one object is shown; and

[0223] Figure 13 Another exemplary spectrometer apparatus including a reference target is shown. DETAILED DESCRIPTION

[0224] exist Figure 1 , a schematic overview of a spectrometer device 110 for obtaining spectroscopic information about at least one object 112 is shown. The spectrometer device 110 may comprise Figure 1 The following will refer to the multiple components shown. Figure 1Possible components of a spectrometer device 110 and their interactions are described. Spectrometer device 110 includes at least one light source 114 for generating illumination light 116 for illuminating an object 112. Light source 114 can be at least one of a tunable light source, a light source having at least one fixed emission wavelength, and a broadband light source. Light source 114 can specifically be or include at least one electric light source. Light source 114 includes at least one light-emitting diode 118 and at least one luminescent material 120 for photoconverting primary light generated by light-emitting diode 118. By way of example, light-emitting diode 118 can include one or more of the following: a light-emitting diode (LED) based on spontaneous optical emission, a light-emitting diode (sLED) based on superluminescent emission, or a laser diode (LLED).

[0225] LED 118 may specifically include at least two semiconductor material layers 121, wherein light may be generated at at least one interface between the at least two semiconductor material layers 121, specifically due to the recombination of positive and negative charges. The at least two semiconductor material layers 121 may have different electrical properties, such as at least one of the layers being an n-doped semiconductor material 121 and at least one of the layers being a p-doped semiconductor material 121. Thus, as an example, LED 118 may include at least one pn junction and / or at least one pin structure. However, it should be noted that other device structures are also possible.

[0226] The light-emitting diodes 118 can generate primary light, which can also be referred to as "pump light." The primary light can then be converted into "secondary light," for example, using light conversion (e.g., by one or more luminescent materials 120, such as phosphor materials). Thus, at least one luminescent material 120 can form at least one converter (also referred to as a light converter) that converts the primary light into secondary light having different spectral characteristics than the primary light. Specifically, the spectral width of the secondary light can be greater than the spectral width of the primary light, and / or the emission center of the secondary light can be offset (specifically, red-shifted) compared to the primary light. Specifically, the at least one luminescent material 120 can have an absorptive property in the ultraviolet and / or blue spectral ranges, and an emissive property in the near-infrared and / or infrared spectral ranges. The illumination light 116 can be or include at least one of the primary light or a portion thereof, the secondary light or a portion thereof, or a mixture of the primary light and the secondary light.

[0227] like Figure 1As indicated, the light source 114 may specifically include a phosphor light emitting diode 122, also referred to as a phosphor LED 122. The 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 (also referred to as a "phosphor") configured to photoconvert the primary light generated by the light emitting diode 118. The 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 that, for example, fully or partially coats the LED 118 and, as an example, is configured to convert the primary light or blue light into light having different spectral characteristics (specifically, into near-infrared light). Figure 2 A more detailed view of the light source 114 implemented as a phosphor LED 122 is shown.

[0228] Generally, the light source 114 can be implemented in various ways. Thus, the light source 114 can be, for example, a part of the spectrometer device 110 in the housing 126 of the spectrometer device 110, such as Figure 1 However, alternatively or additionally, the at least one light source 114 can also be arranged outside the housing 126, for example as a separate light source 114 (not shown). The light source 114 can be arranged separately from the object 110 and illuminate the object 110 from a distance, such as Figure 1 As indicated.

[0229] Illumination light 116 generated by light source 114 may propagate from light source 114 to object 112. Figure 1 , illumination light 116 generated by a light source 114 and propagating to an object 112 is illustrated by an arrow. Specifically, the object 112 may include at least one sample that may be analyzed completely or partially by spectroscopic methods.

[0230] As from Figure 1 As apparent in FIG, the spectrometer device 110 further includes at least one detector 128 configured to detect detection light 130 from the object 112. The light propagating from the light source 114 to the object 112 may be referred to as illumination light 116, while the light propagating from the object 112 to the detector 128 may be referred to as “detection light” 130. Figure 1, detection light 130 is indicated by an arrow. Detection light 130 may include at least one of the following: illumination light 116 reflected by object 112, illumination light 116 scattered by object 112, illumination light 116 transmitted by object 112, or luminescent light generated by object 112 (e.g., phosphorescence or fluorescence generated by object 112 after object 112 is optically, electrically, or acoustically excited by illumination light 116). Therefore, detection light 130 may be generated directly or indirectly by illumination light 116 irradiating object 112.

[0231] Detector 128 may be or include at least one optical detector 132. Optical detector 132 may be configured to determine at least one optical parameter, such as the intensity and / or power of light irradiating at least one sensitive area of ​​detector 132. More specifically, optical detector 132 may include at least one photosensor and / or at least one optical sensor, such as at least one of a photodiode, a photocell, a photoresistor, a phototransistor, a thermopile sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier, and a bolometer. Thus, detector 128 may be configured to generate at least one detector signal, more specifically at least one electrical detector signal in the aforementioned sense, that provides information about at least one optical parameter, such as the power and / or intensity of light irradiating detector 128 or a sensitive area of ​​detector 128.

[0232] Detector 128 may include a single optically sensitive element or region or a plurality of optically sensitive elements or regions. Figure 1 As indicated, detector 130 may include at least one detector array, more specifically an array of photosensitive elements 134. Each photosensitive element 134 may be configured to generate at least one detector signal. In particular, each photosensitive element 134 may include at least a photosensitive area that may be adapted to generate an electrical signal depending on the intensity of incident light, wherein the electrical signal may in particular be provided to an evaluation unit 136 of the spectrometer device, as will be further detailed below.

[0233] In the case where detector 128 comprises an array of optically sensitive elements 134, detector 128 can, for example, be selected from any known pixel sensor, in particular from a CCD chip or a CMOS chip. Alternatively, detector 128 can generally be or include a photoconductor, in particular an inorganic photoconductor, especially PbS, PbSe, Ge, InGaAs, extended InGaAs, InSb, or HgCdTe. As another alternative, the detector can include at least one of a pyroelectric element, a bolometer element, or a thermopile detector element.

[0234] The spectrometer device 110 comprises at least one evaluation unit 136 for evaluating at least one detector signal generated by the detector 128 and for deriving spectroscopic information about the object 112 from the detector signal. The detector 128 can directly or indirectly provide the detector signal to the evaluation unit 136. Thus, the detector 128 and the evaluation unit 136 can be directly or indirectly connected, e.g. Figure 1 The detector signal can be used as a "raw" detector signal and / or can be processed or pre-processed (e.g., by filtering, etc.) before further use. Thus, the detector 128 can include at least one processing device and / or at least one pre-processing device, such as at least one of an amplifier, an analog / digital converter, an electrical filter, and a Fourier transform.

[0235] like Figure 1 As shown, the spectrometer device 110 further comprises at least one driving unit 138 for electrically driving the light source 114. The spectrometer device 110 comprises at least one measuring unit 139. The measuring unit 139 may be configured to generate at least one information item about at least one electrically measurable quantity (in particular a forward voltage) required to drive the light emitting diode 118. The measuring unit 139 may be a component of the driving unit 138, such as Figure 1 as indicated. In particular, the driving unit 138 may be configured to provide a current to the LED 118, specifically to control the current through the LED 118. Therein, as an example, the driving unit 138 may be configured to adapt and measure a voltage provided to the LED 118, which voltage is required to achieve a specific current through the LED 118. The driving unit 138 may specifically include one or more of the following: a current source 140, a voltage source, a current measuring device (such as an ammeter), a voltage measuring device 142 (such as a voltmeter), 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 LED 118, wherein the current source 140 may specifically be configured to adjust or control the voltage applied to the LED 118 so as to generate the predetermined current. As an example, the driving unit 138 may include one or more electrical components (such as integrated circuits) 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 preferred. Figure 1 In display.

[0236] As outlined above, the driving unit 138 may further be configured to generate at least one item of information about 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 the forward direction, i.e., by applying the positive contact of the voltage or current source 140 to the p-layer of the LED 118 and the negative contact to the n-layer of the LED 118, in order to generate a predetermined current through the LED 118. As an example, the predetermined current defining the forward voltage may be a current known to generate a predetermined light output of the light source 114 and / or the light-emitting diode 118.

[0237] To generate at least one item of information about at least one electrically measurable quantity (particularly forward voltage) required to drive light-emitting diode 118 (e.g., driving LED 118 in the forward direction with a predetermined current), measurement unit 139 may include one or more measuring devices or measuring elements, such as one or more voltage measuring devices 142. By way of example, the at least one item of information about the at least one electrically measurable quantity (particularly forward voltage) may be provided by measurement unit 139 in the form of at least one electrical signal and / or electrical information, such as one or both of an analog signal and a digital signal. The electrical signal including the at least one item of information about the at least one electrically measurable quantity (particularly forward voltage) may be provided directly or indirectly to evaluation unit 136. The electrical signal may be time-dependent or static.

[0238] As outlined above, and as Figure 1 As shown, spectrometer device 110 includes at least one evaluation unit 136 for evaluating at least one detector signal generated by detector 128 and for deriving spectroscopic information about object 112 from the detector signal. Evaluation unit 136 is configured to take into account, in particular, wavelength correction information derived from the at least one detector signal when deriving the spectroscopic information from the detector signal.

[0239] The evaluation unit 136 is configured to determine the wavelength correction information by using the position of the emission peak 193 of at least one emission band in the power spectral density distribution of the wavelengths of the light 116, 130, 256 generated by the light source 114. The emission band is a characteristic that is specific and / or exclusive to the secondary light generated by the material of the phosphor.

[0240] The emission peak 193 position of at least one emission band in the power spectral density distribution of the wavelength of light 116, 130, 256 used to determine wavelength correction information can be used to calibrate the wavelength of the spectroscopic information. The light can be illumination light 116 and / or can be generated by illumination light 116.

[0241] The at least one evaluation unit 136 may be configured to determine the wavelength correction information on site.

[0242] The at least one detector 128 may be configured to generate at least one detector signal by detecting at least one of:

[0243] Illumination light 116 from light source 114,

[0244] Detection light 130 from object 112; or

[0245] light 256 from at least one reference target 254;

[0246] Therein, the evaluation unit 136 may be configured to determine wavelength correction information, in particular wavelength correction information determined from a position of an emission peak 193 of at least one emission band in a power spectral density distribution of the wavelength of the respective detected light 116 , 130 , 256 .

[0247] At least one detector signal evaluated to derive spectroscopic information about object 112 may include wavelength correction information. Before deriving spectroscopic information about object 112, the position of an emission peak 193 of at least one emission band in a power spectral density distribution of the wavelength of the corresponding detected light 116, 130, 256 may be detected by at least one detector 128.

[0248] Evaluation unit 136 can further be configured to take into account information about at least one electrically measurable quantity (particularly the forward voltage) when deriving spectroscopic information from the detector signals. Specifically, evaluation unit 136 can be configured to process at least one input signal and generate at least one output signal thereof. By way of example, the at least one input signal can include at least one detector signal provided directly or indirectly by at least one detector 128 and at least one signal provided directly or indirectly by measurement unit 139, which signal includes at least one information item about at least one electrically measurable quantity (particularly the forward voltage). Figure 1 The drive unit 138 (which includes Figure 1 The arrows between the measuring unit 139 and the evaluation unit 136 in the illustrated embodiment illustrate the provision of a signal to the evaluation unit 136 and / or the retrieval of a signal by the evaluation unit 136 , the signal comprising at least one item of information about at least one electrically measurable quantity, in particular the forward voltage.

[0249] The evaluation unit 136 may be or may 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. Additional components may be included, such as one or more pre-processing devices 146 and / or data acquisition devices, such as one or more devices for receiving and / or pre-processing detector signals, such as one or more A / D converters and / or one or more filters. Furthermore, the evaluation unit may include one or more data storage devices 148, such as Figure 1 Furthermore, the evaluation unit 136 may include one or more interfaces, such as one or more wireless interfaces and / or one or more wired interfaces.

[0250] Specifically, evaluation unit 136 can be configured, for example through software programming, to determine at least one correction based on information about at least one electrically measurable quantity (particularly the forward voltage), specifically a correction based on a model describing the functional relationship between the spectral characteristics of light source 114 and the at least one electrically measurable quantity (particularly the forward voltage). Evaluation unit 136 can further be configured to correct at least one detector signal using the correction. As described in detail above and further exemplarily described below, the correction can specifically include multiplying the at least one detector signal by at least one correction factor. Evaluation unit 136 can specifically be configured to use the corrected detector signal to derive spectroscopic information.

[0251] As described in more detail above, the detector 128 can specifically include an array of photosensitive elements 134. Each photosensitive element can be configured to generate at least one detector signal. The evaluation unit 136 can be configured to individually correct each detector signal and to combine the detector signals to obtain spectroscopic information. The spectrometer device 110 can be configured such that the photosensitive elements of the detector 128 are sensitive to different spectral ranges of the light from the object 112. In particular, the detector 128 can be configured to generate detector signals for at least two different spectral ranges of the light from the object, specifically in a manner at least one of sequential and simultaneous. The spectrometer 110 can specifically include at least one filter element 150 arranged in the beam path of the light from the object. The filter element 150 can specifically be configured such that each photosensitive element is exposed to a separate spectral range of the light from the object 112.

[0252] The spectrometer device 110 may further include one or more optical components 151, such as one or more of at least one mirror, at least one lens, at least one aperture, and at least one wavelength selective element 152. Specifically, the one or more optical components 151 may be arranged in at least one of the beam path of the illumination light 116 and the beam path of the detection light 130. The spectrometer device 110 may particularly include at least one wavelength selective element 152. The wavelength selective element 152 may be selected from the group consisting of a tunable wavelength selective element 152 and a wavelength selective element 152 with a fixed transmission spectrum. By way of example, a tunable wavelength selective element 152 allows for sequential selection of different wavelength ranges, while a wavelength selective element 152 with a fixed transmission spectrum allows for a fixed wavelength range selection, or may also depend on, for example, the detector position. The wavelength selective element 152 may be used to separate incident light into a spectrum of component wavelength signals, the respective intensities of which are determined using a detector (such as the detector 128 of the spectrometer device 110, which may include an array of photosensors 134). The at least one wavelength selection element 152 may include, for example, at least one of a filter, a grating, and a prism. The wavelength selection element 152 may specifically include at least one of a wavelength selection element 152 disposed in the beam path of the illumination light 116 and a wavelength selection element 152 disposed in the beam path of the detection light 130. Figure 1 An embodiment of a spectrometer device 110 is shown having one wavelength selective element 152 arranged in the beam path of the illumination light 116 and one wavelength selective element 152 arranged in the beam path of the detection light 130 .

[0253] like Figure 1The spectrometer device 110, schematically shown in FIG. 1 , is configured to obtain spectroscopic information about at least one object 112. Specifically, the spectrometer device may be configured to obtain, for example, an item of information about the at least one object and / or radiation emitted by the at least one object, the information item characterizing at least one optical property of the object, more specifically, at least one item of information characterizing, for example, at least one of the transmission, absorption, reflection, and emission of the at least one object qualitatively and / or quantitatively. By way of example, the at least one spectral information item may include at least one item of intensity information, such as information about the intensity of at least one of light transmitted, absorbed, reflected, or emitted by the object, for example, as a function of wavelength or a wavelength subrange within one or more wavelengths (e.g., within a wavelength range). Thus, the spectrometer device 110 may be configured to acquire at least one spectrum, or at least a portion of a spectrum, of detection light 130 propagating from the object 112 to the detector 128. The spectrum may describe a radiometric measurement of the spectral flux, for example, given in watts per nanometer (W / nm), or other units, for example, as a function of the wavelength of the detection light. Thus, the spectrum may describe the optical power of light within a specific wavelength band, for example, within the NIR spectral range. A spectrum may include one or more optical variables that vary with wavelength, such as power spectral density, an electrical signal obtained by optical measurement, etc. Examples of spectra are Figure 4 、 Figure 7A and Figure 7B The spectrometer device 110 may specifically be a portable spectrometer device 110 , which may in particular be used on site.

[0254] exist Figure 2 A schematic cross-sectional view of a light source 114 is shown in FIG. The at least one light source 114 of the spectrometer device 110 can be configured to generate or provide electromagnetic radiation in one or more of the infrared, visible, and ultraviolet spectral ranges. Because many material properties or chemical composition characteristics of many objects 112 can be derived from the near-infrared spectral range, light typically used for the purposes of the present invention is light in the infrared (IR) spectral range, more preferably in the near-infrared (NIR) and / or mid-infrared (MidIR) spectral ranges, particularly light with a wavelength of 1 to 5 µm, preferably 1 to 3 µm. The light source 114 includes at least one light-emitting diode 118 and at least one luminescent material 120 for photoconverting the primary light generated by the light-emitting diode 118. As described above, the LED 118 and the luminescent material 120 together can form a phosphor LED 122.

[0255] like Figure 2As shown, the phosphor LED 122 may include one or more functional components. Specifically, the phosphor LED 122 may include one or more substrates 154, specifically one or more electrically insulating substrates 154. In particular, the phosphor LED 122 may include one or more ceramic substrates 156, such as Figure 2 As shown. The substrate 154 can be configured to hold at least one LED die 124 and at least one luminescent material 120. Further, at least one substrate 154 can hold or include one or more electrical connection components, such as Figure 2 One or more contact pads 158 and / or one or more electrical leads, such as one or more metal contacts and / or one or more metal leads, are shown. The substrate 154 can be configured to act as a heat sink. For example, during the conversion process, heat can be generated in the LED die 124 (e.g., due to the finite conversion of electrical energy to photon energy) and in the luminescent material 120. The heat can be dissipated in the substrate 154, such as a ceramic substrate.

[0256] like Figure 2 As shown, the phosphor LED 122 may include a light emitting diode 118. The light emitting diode 118 may be configured to use Figure 2 The at least one LED chip and / or at least one LED die 124 shown converts electric current into primary light, such as blue primary light. In particular, a pn junction diode can be used. As an example, one or more LEDs 118 selected from the group consisting of an indium gallium nitride (InGaN)-based LED 118, a GaN-based LED 118, an InGaN / GaN alloy-based LED 118, or a combination thereof, and / or other LEDs 118 can be used. Additionally or alternatively, quantum well LEDs 118 can also be used, such as one or more quantum well LEDs 118 based on InGaN. Additionally or alternatively, superluminescent LEDs (sLEDs) and / or quantum cascade lasers can be used. As described in Figure 2 As will be further apparent from the above, the phosphor LED may include at least one luminescent material 120 configured to light-convert 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:Ce 3+ or Y3Al5O 12 :Ce 3+ ); rare earth-doped Sialon; copper and aluminum co-doped zinc sulfide (ZnS:Cu,Al).

[0257] The luminescent material 120 may in particular form at least one layer. In general, various alternatives for positioning the luminescent material 120 relative to the light-emitting diode 118 are feasible, which may be used individually or in combination. Firstly, the luminescent material 120 (e.g. at least one layer of the luminescent material 120, such as a phosphor) may be positioned directly on the light-emitting diode 118, e.g. with no material between the LED 118 and the luminescent material 120, or with one or more transparent materials in between, such as one or more transparent materials (in particular transparent for the primary light) between the LED and the luminescent material 120. Thus, as an example, a coating of the luminescent material 120 may be placed directly or indirectly on the LED 118 (not shown). Additionally or alternatively, as an example, the luminescent material 120 may form at least one converter 160, such as at least one converter disc, which may also be referred to as a converter sheet. The converter 160 may be placed on top of the LED 118, e.g. as Figure 2 As shown, the converter 160 is attached to the LED 118 with an adhesive. Additionally or alternatively, the luminescent material 120 can be remotely positioned, such that the primary light from the LED 118 must traverse an intermediate light path before reaching the luminescent material 120 (not shown). Again, by way of example, the remotely positioned luminescent material can form a solid or converter 160, such as a disk or converter disk. One or more optical elements, such as one or more lenses, prisms, gratings, mirrors, apertures, or combinations thereof, can be positioned in the intermediate light path. Thus, in particular, an optical system with imaging properties can be positioned in the intermediate light path, between the LED 118 and the luminescent material 120. Thus, by way of example, the primary light can be focused or concentrated onto the converter 160.

[0258] In the light source 114 (specifically, the phosphor LED 122), at least one luminescent material 120 can be positioned relative to the light emitting diode 118 such that heat can be transferred from the light emitting diode 118 to the luminescent material 120. More specifically, the luminescent material 120 can be positioned such that heat can be transferred by one or both of thermal radiation and thermal conduction (more preferably by thermal conduction). Thus, as an example, the luminescent material 120 can be in thermal contact and / or physical contact with the light emitting diode 118, such as Figure 2 Thus, generally, the temperature of the light emitting material 120 and the temperature of the light emitting diode 118 can be coupled.

[0259] like Figure 2As shown, the light source 114 (specifically, the phosphor LED 122) can include additional components, such as at least one side coating 162 that covers at least one side (e.g., a top side, a bottom side, and / or one or more lateral sides) of at least one of the following: the substrate 154, the contact pads 158, the light emitting diode 118, and the luminescent material 120. In particular, the side coating 162 can cover voids and / or gaps that may be present in the layered arrangement of the light source 114, such as Figure 2 As shown. Other components of the light source 114 (specifically Figure 2 Typically, the light source 114 (particularly the phosphor LED 122) can be packaged in a housing ( Figure 2 Thus, the LED 118 and the at least one luminescent material 120 for light conversion of the primary light generated by the light emitting diode 118 can be accommodated in a common housing. Alternatively, however, the LED 118 can also be a housingless or bare LED 118, such as Figure 2 What is shown.

[0260] Figure 3 The schematic flow chart of FIG. 1 shows the process of generating a detector signal and processing the detector signal to generate a corrected signal, for example. Figure 3 , hardware components 164 that may participate in this process or in the generation and / or preprocessing of the detector signal, as well as software components 166 that may participate in the processing and / or correction of the detector signal, are shown. Hardware components 164 (also referred to simply as "hardware" 164) may specifically include at least one light-emitting diode 118 (particularly a blue LED 118) of the spectrometer device 110 configured to emit blue primary light. Hardware components 164 may further include a luminescent 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-selective element 152), and a detector 128.

[0261] As part of the corrections that can be performed by the evaluation unit 136, corrections can be performed for temperature changes (even for local temperature changes within the light source 114), which may have an influence on the emission characteristics of the light source 114. Figure 3, the temperature of the selected hardware component 164 is indicated in FIG. For example, depending on the arrangement of the hardware component 164 (such as the relative position and distance of the hardware component in the spectrometer device 110), the hardware component 164 may have different or the same temperature. Specifically, as described above, the temperature of the luminescent material 120 and the temperature of the luminescent diode 118 may be coupled, for example, due to heat transfer caused by one or both of thermal radiation and thermal conduction between the LED 118 and the luminescent material 120. Therefore, in particular, the temperature of the LED 118 (also referred to as "T pn ”) and the temperature of the luminescent material 120 (also referred to as “T Ph ”) can be similar or even identical. Figure 3 In FIG. 1 , 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 (also referred to as “T D ”) is indicated by reference numeral 172.

[0262] When current flows through the LED 118 (eg, due to the driver unit 138 applying an appropriate voltage to the LED), the LED 118 may emit primary light so as to generate a specific current (eg, a predetermined current). Figure 3 The target signal S indicated by reference numeral 174 in FIG. t , to drive LED 118 to emit blue primary light. In particular, the target signal S t Reference numeral 174 may be a predetermined current value to be generated through the LED 118, for example, by applying an appropriate voltage. Specifically, the predetermined current value may be in the range of 10 mA to 500 mA, more specifically in the range of 100 mA to 300 mA, for example, a current value of 50 mA. Thus, it is known that the predetermined current may generate a predetermined light output of the LED 118, such as a blue primary light. The LED 118 may be 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, for example into light in the infrared spectral range. The luminescent material 120 may be at a temperature “T” indicated by reference numeral 170. ph”. The object 112 may be illuminated by illumination light 116 generated by the light source 114, which illumination light may include at least one of primary light or a portion thereof, secondary light or a portion thereof, or a mixture of primary light and secondary light. In order to guide the illumination light 116, one or more optical components 151 (such as one or more mirrors, lenses, wavelength selection elements 152 or other optical components 151) may be used, for example by placing the optical component 151 in the beam path of the illumination light 116. Detection light from the object 112 (such as reflected light) may be guided to the detector 128. In the beam path of the detection light 130, one or more optical components 151 may also optionally be used. As an example, one or more wavelength selection elements 152, such as one or more dispersive elements, may be used, for example to separate the detection light 130 into its spectral components.

[0263] As described in more detail above, the detector 128 may, for example, include an array of photosensitive elements 134. Specifically, the detector 128 may be or may include a pixel sensor, such as a CCD chip or a CMOS chip, which includes a plurality of pixels arranged on the chip. As an example, each pixel may correspond to a predetermined spectral range, for example, by being sensitive to the predetermined spectral range. Thus, the detector 128 may generate a detector signal S px,i 176, such as Figure 3 As indicated by reference numeral 176 in the diagram, the detector signal comprises a plurality of detector signals. Thus, each of the plurality of detector signals may correspond to an electronic signal generated by one of the plurality of pixels of the detector 128. Each of the plurality of detector signals may be given, for example, as a numerical value corresponding to the number of counts of the corresponding pixel measured, for example, during a predetermined time span. Thus, the detector signal S px,i 176 may specifically be a function of the wavelength of the detection light 130, as indicated by the index "px". px,i 176 may further be a function of time (eg in the case of a time-dependent detector signal), as indicated by the index "i".

[0264] Detector signal S px,i The multiple signals included in 176 can be generated simultaneously or in a temporally continuous manner. px,i 176 can be used as Figure 3 The detector signal S is determined by the readout electronics 178 shown. px、i 176 can be processed, for example, as part of pre-processing and / or as part of a further processing step. As an example, the pixels comprised by the detector 128 can specifically be active pixel sensors that can be adapted to amplify the electronic detector signal S px,i176 , for example as part of a pre-processing process prior to further processing that may be performed, for example, by one or more of the software components 166 .

[0265] The signal S generated by the detector 128 px,i 176 may also be referred to as "frame signal S px,i 176". Figure 3 The provision of a signal S to one of the software components 166 is shown by an arrow. px,i 176 process. Specifically, it is configured to process and / or correct the detector signal S px,i The software component 166 of 176 may include at least one first software 180 (also referred to as “software 1”) and at least one second software 182 (also referred to as “software 2”). The first software 180 may be configured to detect the detector signal S px,i 176 performs at least one first processing step 184 (also referred to as “processing 1”), for example by applying at least one algorithm to the detector signal S px,i 176. In particular, the first processing step 184 may comprise at least one correction for transient effects or time-dependent effects. Thus, as an example, the first processing step 184 may comprise one or more of the following: a correction for a dark signal; a correction for a dark signal drift; a correction for fluctuation effects; a correction for the photodetector response of individual detector elements or individual time steps; a correction for environmentally induced (e.g. temperature-induced) variations in the photodetector response; extraction of information for subsequent processing; an addition or multiplication with a parameter, the addition or multiplication being generated based on information about at least one electrically measurable quantity (in particular the forward voltage) or about the device temperature. The first software 180 may be configured to perform at least one further step comprising performing at least one fast Fourier transformation 186 on the detector signal. Thus, as an example of applying the first processing step 184 and / or the fast Fourier transformation 186 to the detector signal S px,i 176, a signal S can be generated px 188 (also called "pixel signal S px 188”), the signal may no longer be a function of time. Specifically, the frame signal S px,i The time dependency of 176 can be eliminated by one or more of the steps forming part of the first software component 1, whereas the wavelength dependency may still be present in the start signal S px 188, as indicated by the index "pn". Figure 3 The provision of the signal S to the second software 182 is further illustrated by an arrow. px 188 process. The second software 182 can be configured to px188 performs at least one second processing step 190 (also referred to as “processing 2”), for example by applying at least one algorithm to the signal S px 188, thereby generating at least one corrected signal S px,corr 191. In particular, the second processing step 190 may comprise one or more of the following: correction of the dark signal; correction of dark signal drift; correction of fluctuation effects; correction of the photodetector response of individual detector elements or individual time steps; correction of environmentally induced (e.g. temperature induced) photodetector response variations; extraction of information for subsequent processing; manipulation of at least one parameter, e.g. addition or multiplication with a parameter, the addition or multiplication being generated as a function of information about at least one electrically measurable quantity (e.g. forward voltage) or about the device temperature. In particular, the corrected signal S px,corr 191 may include a plurality of corrected signals, such as a plurality of corrected electronic signals. Each of the plurality of corrected signals may specifically correspond to a corrected count number of a corresponding pixel.

[0266] Spectrometer device 110 includes at least one evaluation unit 136 for evaluating at least one detector signal generated by detector 128 and for deriving spectroscopic information about object 112 from the detector signal. 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 spectroscopic information from the detector signal. Evaluation unit 136 can be configured, in particular by software programming, to evaluate and / or process the detector signal as part of a first processing step 184 of at least one first software 180. Evaluation unit 136 can specifically be configured to determine at least one correction based on the information about the at least one electrically measurable quantity (in particular, the forward voltage) and can further be configured to correct the at least one detector signal by using the correction. Thus, evaluation unit 136 can process and correct signal S px 188 to generate a signal S px,i,corr , the signal may then be further processed, for example by applying a Fast Fourier Transform 186 .

[0267] For example, as described in more detail above, both the light emitting diode 118 and the luminescent material 120 can be based on different materials and / or different material compositions, which generally affects the spectrum 192 of the phosphor LED 122. However, even when operated at a specific predetermined current, the spectrum 192 or spectral characteristics of a particular phosphor LED 122 may change with temperature. These changes can include a shift in the emission peak 193, a broadening or narrowing of the spectrum 192, an increase or decrease in emission, etc. However, in many cases, the emission at some wavelengths is affected to a greater extent than the emission at other wavelengths. This effect is caused by Figure 4 The graph shown shows a superposition of infrared radiation spectra 192 of phosphor LEDs 122 at various temperatures. Specifically, Figure 4 The graph in FIG shows the variation of power spectral density (PDS) 194 in microwatts per nanometer (µW / nm) on the y-axis 196 as a function of wavelength 198 given in nanometers on the x-axis 200. For the spectrum 192 shown, the temperature range over which the phosphor LED 122 generates illumination light 116 is from 25°C to 50°C. Typically, there is a specific central wavelength or emission peak 193 location within the spectrum 192 where the power spectral density generally does not vary with temperature. Therefore, each wavelength generally has its own temperature coefficient with respect to the increment / decrement of power. Thus, as shown from Figure 4 As is evident in Figure 19, the shape of the spectrum 192 changes with temperature. To visualize this effect more clearly, Figure 4 192. The wavelength intervals are delimited by dashed lines. Specifically, the following four wavelengths and their corresponding intervals are labeled with the following reference numerals: 1643 nm is indicated by reference numeral 202, 1750 nm is indicated by reference numeral 204, 1802 nm is indicated by reference numeral 206, and 1950 nm is indicated by reference numeral 208. Figure 4 It follows that the emission peak 193 position of the corresponding feature 210 in at least one emission band in the power spectral density 194 distribution of the wavelengths of the light 116, 130, 256 used to determine the wavelength correction information may be independent of the temperature of the light source 114. For each of these wavelengths, Figure 5 The graph shows the variation of the transmit power normalized to the transmit power variation at 25°C over the temperature range from 25°C to 50°C. Figure 5 In the graph of , the transmit power variation (given in percentage) normalized to the transmit power variation at 25°C is shown on the y-axis 196 and denoted by reference numeral 219 , while the temperature in °C (denoted by reference numeral 220 ) is indicated on the x-axis 200 .

[0268] Figure 5 The line in the graph in indicates the fitted curve 236. Figure 5 As is apparent from the graph, the emission power at the central wavelength of 1802 nm can have very little variation (i.e., the emission power variation is zero or close to zero) over the observed temperature range, whereas for other wavelengths (e.g., for 1643 nm or 1953 nm), the emission power variation can have significant variation.

[0269] When a specific current (e.g., a current of a specific predefined value) is generated through the light emitting diode 118 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. Therefore, when the same current is applied to the light emitting diode 118, the forward voltage of the LED 118 generally decreases as the temperature increases. Each type of LED 118 has its own forward voltage-temperature characteristic curve. Generally, the forward voltage of the LED 118 decreases linearly as the temperature increases, such as when the temperature of the LED 118 is higher. to Slope in the range of V / K. Figure 6 This relationship is demonstrated for a particular LED 118. In particular, Figure 6 The graph shows the forward voltage applied to the LED 118 for generating a DC current of 150 mA through the LED 118 as a function of the temperature of the LED 118. The forward voltage in volts is indicated by reference numeral 224 on the y-axis 196. The temperature in °C is indicated by reference numeral 220 on the x-axis 200. Figure 6 As is evident from the figure, in this case the forward voltage decreases linearly with increasing temperature. Figure 5 The curve in can be described by the following equation:

[0270]

[0271] in, represents the forward voltage and Indicates temperature. Figure 6 In the diagram of FIG, a measurement point 221 represented by a gray solid circle and a dashed line corresponding to the above-given fitting curve 236 are shown. Instead of the relationship and / or curve between the forward voltage and the temperature as described above in an exemplary manner, a relationship between another electrically measurable quantity required to drive the light source and the temperature can be used, such as the fed electric power; current, resistance, inductance, capacitance, etc.

[0272] Thus, by using at least one electrically measurable quantity (in particular the forward voltage) as a correction parameter, the spectra 192 at different wavelengths can be individually temperature corrected. Specifically, the evaluation unit 136 can be configured to individually correct the detector signal S px,i The method further comprises the steps of: generating a plurality of detector signals and combining the individually corrected detector signals to obtain spectroscopic information. As outlined above, the individual corrections can be performed by using an array of photosensitive elements 134, wherein each photosensitive element can be configured to generate at least one detector signal, and wherein each detector signal can be individually corrected using at least one electrically measurable quantity (particularly forward voltage) as a correction parameter. Finally, the corrected detector signals can be combined to obtain spectroscopic information.

[0273] In order to obtain spectroscopic information (in particular, a spectrum) about the object 112, the spectrometer device 110 (in particular, the evaluation unit 136) can specifically take into account the properties of the luminescent material 120 used in the light source 114. As outlined in more detail above, the luminescent material 120 can be configured to absorb primary photons generated by the light-emitting diode 118 and, in response, can emit secondary photons either instantaneously or after a delay or decay time. The signal or emission of the phosphor LED 122 after the forward current is turned off can be described using equations (1) and (2) as described above.

[0274] Thus, the characteristic of the luminescent material 120 may in particular be the decay constant 228 and the growth constant , the decay constant can describe the typical time of afterglow of the luminescent material 120, and the growth constant can describe the typical time to reach saturation of emission of the converted light. and The decay constant is typically different between different phosphor LEDs 122 and / or between different types of luminescent materials 120. and the growth constant Can depend on wavelength. The time constant is usually extracted from the step response of the optical signal by applying / cutting off the forward current. Figure 7A and Figure 7B Spectra 192 of two different types of phosphor LEDs 122 that emit light in the near infrared range are shown. Specifically, the power spectral density is shown as a function of wavelength, which is given in nm. Figure 7A and Figure 7B As is apparent from FIG, the spectra 192 of the two different phosphor LEDs 122 are different. Thus, as an example, Figure 7AThe spectrum 192 shown in FIG reflects high emission in the range from 1400 nm to 1600 nm, whereas emission in this region is negligible for the phosphor LED 122, which has a spectrum 192 in the range of 1400 nm to 1600 nm. Figure 7B The phosphor LED 122 (whose spectrum is Figure 7A The decay constant is shown in and the growth constant respectively Figure 8A and Figure 8B The phosphor LED 122 (whose spectrum is given in Figure 7B The decay constant is shown in and the growth constant respectively Figure 9A and Figure 9B is given as a function of wavelength. Specifically, Figure 8A and Figure 9A The corresponding decay constant in ms is shown on the y-axis 196 (indicated by reference numeral 228 ) versus wavelength 198 in nm on the x-axis 200 ; and Figure 8B and Figure 9B The corresponding growth constant in ms is shown on the y-axis 196 (indicated by reference numeral 230) versus wavelength 198 in nm on the x-axis 200. Data points from different replicates are marked with different shades of grey.

[0275] Another characteristic of LEDs 118 is that their light output power varies with forward current. Thus, generally, by increasing the forward current (specifically, the input current), the power emitted by LED 118 increases. The shape (e.g., slope) of the light output versus forward current curve is characteristic of each LED 118. Figure 10 An example of such a curve is shown in FIG. Figure 10 In the graph of FIG. 2 , normalized light output 232 of a phosphor LED is shown as a function of forward current 234 , which is given in amperes.

[0276] exist Figure 11 , a method 236 for calibrating a spectrometer device 110 for obtaining spectroscopic information about at least one object 112 is shown. The method 236 includes:

[0277] a. In step a. 238: electrically driving at least one light source 114 by using at least one driving unit 138, the light source 114 comprising at least one light-emitting diode 118 and at least one luminescent material 120 for light-converting primary light generated by the light-emitting diode 118;

[0278] b. In step b. 240: detecting light 116, 130, 256 using at least one detector 128 and thereby generating at least one detector signal; and

[0279] c. In step c. 242: evaluating at least one detector signal generated by the detector 128 using at least one evaluation unit 136, and determining wavelength correction information by using, in particular, the position of a feature 210 in the power spectral density distribution of the wavelengths of the light 116, 130, 256 generated by the light source 114, more in particular the position of an emission peak 193 of at least one emission band, and determining the wavelength correction information by using the position of an emission peak 193 of at least one emission band in the power spectral density distribution of the wavelengths of the light 116, 130, 256 generated by the light source 114, wherein the luminescent material 120 is a phosphor, wherein the emission band is a characteristic of the secondary light generated by the material of the phosphor.

[0280] The power spectral density distribution of the wavelengths of the detected light 116 , 130 , 256 may be determined using at least one detector 128 .

[0281] exist Figure 12 In one embodiment, a method 244 of obtaining spectroscopic information about at least one object 112 includes:

[0282] 1. In step 1.246: electrically driving at least one light source 114 by using at least one driving unit 138, the light source 114 comprising 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;

[0283] 2. In step 2.248: illuminating the object 112 with illumination light 116 generated by the light source 114;

[0284] 3. In step 3.250: detecting light 116, 130, 256 by using at least one detector 128 and thereby generating at least one detector signal; and

[0285] 4. In step 4.252: evaluate at least one detector signal by using at least one evaluation unit 136, and obtain spectroscopic information about the object 112 from the at least one detector signal by using the evaluation unit 136, wherein the spectroscopic information about the object 112 is obtained by taking into account, in particular, wavelength correction information obtained from the at least one detector signal.

[0286] The wavelength correction information is determined using a method for calibrating a spectrometer device for obtaining spectroscopic information about at least one object. The method may further include the step of generating at least one item of information about at least one electrically measurable quantity required to drive a light-emitting diode using at least one measuring unit; wherein the item of information about the at least one electrically measurable quantity (particularly the forward voltage) may be further taken into account when deriving the spectroscopic information from the detector signal.

[0287] exist Figure 13 Another exemplary spectrometer device 110 is shown in FIG. Figure 1 Please refer to the reference numerals in the figures where they correspond. The other spectrometer device 110 further includes a reference target 254. Alternatively, the reference target may be a component external to the other spectrometer device 110. The reference target 254 may be illuminated by the illumination light 116. The detector 128 may detect light 250 from the at least one reference target 248.

[0288] List of Reference Numerals

[0289]

[0290]

Claims

1. A spectrometer device (110) for obtaining spectroscopic information about at least one object (112), the spectrometer device (110) comprising: i. at least one light source (114) for generating illumination light (116) for illuminating the object (112), the light source (114) comprising at least one light-emitting diode (118) and at least one luminescent material (120) for light-converting primary light generated by the light-emitting diode (118); ii. at least one detector (128) for detecting light (116, 130, 256) and thereby generating at least one detector signal; iii. at least one evaluation unit (136) configured to derive spectroscopic information about the object (112) from the at least one detector signal, wherein the evaluation unit (136) is configured to derive the spectroscopic information about the object (112) by taking into account wavelength correction information, wherein the evaluation unit (136) is configured to determine the wavelength correction information by using an emission peak (193) position of at least one emission band in a power spectral density distribution of wavelengths of light (116, 130, 256) generated by the light source (114), wherein the luminescent material (120) is a phosphor, wherein the emission band is a characteristic of secondary light generated by the material of the phosphor.

2. The spectrometer device (110) according to the preceding claim, wherein The emission peak (193) position of the at least one emission band in the power spectral density distribution of the wavelength of the light (116, 130, 256) used to determine the wavelength correction information is used to calibrate the wavelength of the spectroscopic information.

3. The spectrometer device (110) according to the two preceding claims, wherein: The position of the emission peak (193) of the at least one emission band in the power spectral density distribution of the wavelength of the light (116, 130, 256) used to determine the wavelength correction information is independent of the temperature of the light source (114).

4. The spectrometer device (110) according to any one of the preceding claims, wherein The at least one evaluation unit (136) is configured to determine the wavelength correction information on-site.

5. The spectrometer device (110) according to any one of the preceding claims, wherein The at least one detector (128) is configured to generate the at least one detector signal by detecting at least one of: Illuminating light (116) from the light source (114), Detection light (130) from the object (112); or light (256) from at least one reference target (254); Therein, the evaluation unit (136) is configured to determine the wavelength correction information by evaluating the corresponding detected light (116, 130, 250).

6. The spectrometer device (110) according to any one of the preceding claims, wherein The at least one detector signal evaluated to obtain the spectroscopic information about the object (112) includes the wavelength correction information.

7. The spectrometer device (110) according to any one of the six preceding claims, wherein Prior to obtaining the spectroscopic information about the object (112), the emission peak (193) position of the at least one emission band in the power spectral density distribution of the wavelength of the corresponding detected light (116, 130, 250) is detected by the at least one detector (128).

8. The spectrometer device (110) according to any one of the preceding claims, wherein The spectrometer device (110) further comprises at least one measuring unit (139) for generating at least one information item about at least one electrically measurable quantity required for driving the light-emitting diode (118), wherein the evaluation unit (136) is further configured to take into account the information item about the at least one electrically measurable quantity when deriving the spectroscopic information from the detector signal.

9. A method for calibrating a spectrometer device (110) for obtaining spectroscopic information about at least one object (112), the method comprising: a. electrically driving at least one light source (114) by using at least one driving unit (138), the light source (114) comprising 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); b. detecting light (116, 130, 256) using at least one detector (128) and thereby generating at least one detector signal; and c. evaluating the at least one detector signal generated by the detector (128) by using at least one evaluation unit (136), and determining wavelength correction information by using a power spectral density distribution of the wavelengths of the light (116, 130, 256) generated by the light source (114), and determining the wavelength correction information by using an emission peak (193) position of at least one emission band in the power spectral density distribution of the wavelengths of the light (116, 130, 256) generated by the light source (114), wherein the luminescent material (120) is a phosphor, wherein the emission band is a characteristic of secondary light generated by the material of the phosphor.

10. The method according to the preceding claim, wherein A power spectral density distribution of wavelengths of the detected light (116, 130, 256) is determined using the at least one detector (128).

11. A method of obtaining spectroscopic information about at least one object (112), the method comprising: electrically driving at least one light source (114) by using at least one driving unit (138), the light source (114) comprising 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); illuminating the object (112) with illumination light (116) generated by the light source (114); detecting light (116, 130, 256) using at least one detector (128) and generating at least one detector signal therefrom; as well as The at least one detector signal is evaluated by using at least one evaluation unit (136), and the spectroscopic information about the object (112) is derived from the at least one detector signal by using the evaluation unit (136), wherein the spectroscopic information about the object (112) is derived by taking into account wavelength correction information, wherein the wavelength correction information is determined by using the method for calibrating a spectrometer device (110) for obtaining spectroscopic information about at least one object (112) according to any one of claims 9 and 10.

12. A computer program comprising instructions which, when executed by an evaluation unit (136) of a spectrometer device (110) according to any of the preceding claims relating to a spectrometer device (110), cause the evaluation unit (136) to perform a method according to any of the preceding claims relating to a method.

13. A non-transitory computer-readable storage medium comprising instructions which, when executed by an evaluation unit (136) of a spectrometer device (110) according to any of the preceding claims relating to a spectrometer device (110), cause the evaluation unit (136) to perform a method according to any of the preceding claims relating to a method.

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