Forward voltage compensation for led2 calibration

Abstract

A method for calibrating a spectrometer device (110), wherein the method comprises the following steps: 1) receiving a dependency / 1(U 1) of a radiation intensity / 1 of the first light emitting element (128) of the spectrometer device (110) depending on a first forward voltage U 1 applied for driving the first light emitting element (128); 2) receiving a dependency I 2(U 2) of a radiation intensity I 2 of a second light emitting element (130) of the spectrometer device (110) depending on a second forward voltage U 2 applied for driving the second light emitting element (130); 3) determining the items of calibration information c R (formula I) and c O (formula II) wherein the determined c R and c O are constants with respects to the first forward voltage U 1 and the second forward voltage U 2.

Description

[0001] 240305WO01

[0002] Forward Voltage Compensation For LED2 Calibration

[0003] Technical Field

[0004] The invention relates to a method for calibrating a spectrometer device, a method for operating a spectrometer device, a spectrometer device, a mobile device, a computer program and a non-transitory computer-readable storage medium.

[0005] The methods and devices according to the present invention specifically may be employed for example in various areas of daily life, security technology, gaming, traffic technology, production technology, photography such as digital photography or video photography for arts, documentation or technical purposes, safety technology, information technology, agriculture, crop protection, maintenance, cosmetics, medical technology or in the sciences. However, other applications are also possible.

[0006] Background art

[0007] Typically, spectrometers are calibrated by using reference standards. For a consumer market a calibration should be performed without a user interaction. In the state of the art, typically factory calibrations and internal calibration targets are used for this purpose.

[0008] Typically an internal calibration target is integrated into the spectrometer, so that light reflected from the internal calibration target that is generated by a light emitting element of the spectrometer device can be detected in absence of an object. In a factory calibration, data generated in this process is used to perform a factory calibration to determine a relation between the detected reflection light and a known reference standard.

[0009] Under the assumption that the relation between the measurements of the internal target and the known reference standard is constant and long term stable, a calibration in the field is performed by using the internal calibration target. This calibration, typically, requires to perform an open port measurement in absence of an object before and / or after the object measurements. The quality of the calibration is limited due to fluctuations of conditions such as a temperature heat up during to the online calibration.

[0010] Such approaches further may have to utilize additional compensation schemes to account for uncertainties caused by the factory calibration of characteristics of a first light emitting element 240305WO01

[0011] - 2 -

[0012] and a second light emitting element. It is still necessary to perform an additional open port measurement, during which it has to be ensured that the open port condition is met. Furthermore, the open port signal is necessarily very small and, thereby, suffers from a lowered signal-to-noise ratio. The second light emitting element may be used for an online calibration. The first light emitting element and the second light emitting element are independent from each other and are therefore emitting light of slightly different power, specifically due to temperature changes.

[0013] Problem to be solved

[0014] It is therefore desirable to provide methods and devices, which at least partially address the above-mentioned technical challenges and at least substantially avoid the disadvantages of known methods and devices.

[0015] In particular, it is an object of the present invention to improve the signal-to-noise ratio of the spectrometer device. Furthermore, it is an object of the present invention to minimize the required calibration measurements. Furthermore, it is an object of the present invention to present an object measurement scheme allowing to derive an item of spectral information on an object not requiring open port measurements and reference calibration target measurements. Furthermore, it is an object of the present invention to present an object measurement scheme being temperature stable and accounting for aging effects of the light emitting elements.

[0016] Summary

[0017] This problem is addressed by a method for calibrating a spectrometer device, a method for operating a spectrometer device, a spectrometer device, a mobile device, a computer program and a non-transitory computer-readable storage medium with the features of the independent claims. Advantageous embodiments which might be realized in an isolated fashion or in any arbitrary combinations are listed in the dependent claims as well as throughout the specification.

[0018] In a first aspect, a method for calibrating a spectrometer device is disclosed. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0019] The steps of the method for calibrating a spectrometer device may be performed in the given order. A different order, however, may also be feasible. Further, two or more of the method steps may be performed simultaneously. Thereby, the method steps may at least partly overlap 240305WO01

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[0021] in time. Further, the method steps may be performed once or repeatedly. Thus, one or more or even all of the method steps may be performed once or repeatedly. The method may comprise additional method steps, which are not listed herein.

[0022] The method for calibrating a spectrometer device may be a computer-implemented method. Alternatively or in addition, at least one of the method steps, preferably any one of the method steps, which involve the use of an evaluation unit, may be performed by using a device comprising at least one processor for executing the steps. The term "computer implemented method" as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a method, which involves at least one apparatus, specifically a computer, or a plurality of apparatus, particularly connected via a computer network. The plurality of apparatus may be connected, particularly for transmitting data, via a network by using at least one connection interface at any one of the apparatuses of the plurality of apparatus. The computer-implemented method may be implemented as at least one computer program that may be provided on a storage medium carrying the computer program, whereby at least one of the steps of the computer-implemented method are performed by using the at least one computer program. Preferably any one of the steps may be performed using the at least one computer program. Alternatively, the at least one computer program may be accessible by an apparatus which may be adapted for performing the method via a network, such as via an inhouse network, via internet, or via a cloud. With particular regard to the present invention, the present method can, thus, be performed on a programmable apparatus, which is configured for this purpose, such as by providing a computer program, which is configured for such a purpose.

[0023] The term “calibrating” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a procedure of determining an item of calibration information. The item of calibration information may be configured for compensating an influence on a desired value to be derived by using the spectrometer device, such as an item of spectral information, wherein the item of calibration information compensates for said influence. Thereby, the desired value may correspond with a reference standard value or a true value.

[0024] The term “spectrometer device” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optical device configured for acquiring at least one item of spectral information on at least one object. 240305WO01

[0025] -4 -

[0026] Specifically, the at least one item of spectral information may refer to at least one optical property or optically measurable property which is determined as a function of a wavelength, for one or more different wavelengths. More specifically, the optical property or optically measurable property, as well as the at least one item of spectral information, may relate to at least one property characterizing at least one of a transmission, an absorption, a reflection and an emission of the at least one object, either by itself or after illumination with external light. The at least one optical property may be determined for one or more wavelengths. The spectrometer device specifically may form an apparatus which is capable of recording a signal intensity with respect to the corresponding wavelength of a spectrum or a partition thereof, such as a wavelength interval, wherein the signal intensity may, specifically, be provided as an electrical signal which may be used for further evaluation.

[0027] The spectrometer comprises at least one sample interface, wherein the sample interface is configured for defining a measurement pose of the at least one object outside of the spectrometer device; at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light; at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one object, at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target.

[0028] As further used herein, the term “light” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to electromagnetic radiation in one or more of the infrared, the visible and the ultraviolet spectral range. Herein, the term “ultraviolet spectral range”, generally, refers to electromagnetic radiation having a wavelength of 1 nm to 380 nm, preferably of 100 nm to 380 nm. Further, in partial accordance with standard ISO-21348 in a valid version at the date of this document, the term “visible spectral range”, generally, refers to a spectral range of 380 nm to 760 nm. The term “infrared spectral range” (I R) generally refers to electromagnetic radiation of 760 nm to 1000 pm, wherein the range of 760 nm to 1.5 pm is usually denominated as “near infrared spectral range” (NIR) while the range from 1.5 p to 15 pm is denoted as “mid infrared spectral range” (MidlR) and the range from 15 pm to 1000 pm as “far infrared spectral range” (FIR). Preferably, light used for 240305WO01

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[0030] the typical purposes of the present invention is light in the infrared (IR) spectral range, more preferred, in the near infrared (NIR) and / or the mid infrared spectral range (MidlR), especially the light having a wavelength of 1 pm to 5 pm, preferably of 1 pm to 3 pm. This is due to the fact that many material properties or properties on the chemical constitution of many objects may be derived from the near infrared spectral range. It shall be noted, however, that spectroscopy in other spectral ranges is also feasible and within the scope of the present invention.

[0031] Consequently, the term “light emitting element”, also referred to as an “illumination source”, as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device configured for generating or providing light, specifically “first light” or “second light” in the sense of the above-mentioned definition for the term “light”. The light emitting element specifically may be or may comprise at least one electrical light source. The “first light”, “second light” that is emitted by the respective light emitting element may be referred to as “illumination light”.

[0032] At least one of

[0033] - the first light emitting element;

[0034] - the second light emitting element;

[0035] may be at least one of:

[0036] - a thermal radiator;

[0037] - a microelectromechanical system (MEMS)-based emitter;

[0038] - a laser, specifically a vertical cavity surface emitting laser (VCSEL), particularly emitting at least one wavelength in the infrared region;

[0039] - a light-emitting diode (LED), particularly

[0040] o a LED emitting light that is at least partially located in the infrared spectral range and / or

[0041] o a LED illuminating a phosphor for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range.

[0042] The light emitting element may be a thermal radiator. The thermal radiator may be selected from an incandescent lamp or a thermal infrared emitter. The term “incandescent lamp” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an electric light having a heatable element, such as a wire filament heated, which is capable of being heated to a temperature at which it emits light, 240305WO01

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[0044] especially infrared light. Since the incandescent lamp can, therefore, be considered as a thermal emitter within the infrared spectral range, an emission power of the incandescent lamp decreases with increasing wavelength. The thermal radiator may be selected from an incandescent lamp or a thermal infrared emitter. The term “thermal infrared emitter” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a micro-machined thermally emitting device, which comprises a radiation emitting surface as the light emitting element that emits the optical radiation to be monitored.

[0045] Alternatively or in addition, the light emitting element may be a microelectromechanical system (MEMS)-based emitter. The term “microelectromechanical system (MEMS)-based emitter” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary apparatus configured for generating and / or emitting light comprising at least one element, wherein the element is associated with MEMS technology. MEMS technology, typically, involves the manufacture of mechanical and / or electrical elements on a microscale, typically below 1 pm or 100 pm or 1 mm or 5 mm or 50 mm. Alternatively or in addition, the light emitting element may be a laser, specifically a vertical cavity surface emitting laser (VCSEL), particularly emitting at least one wavelength in the infrared region.

[0046] The term “vertical-cavity surface-emitting laser” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a semiconductor laser diode configured for laser beam emission perpendicular with respect to a top surface. VCSELs are generally known to the skilled person such as from WO 2017 / 222618 A.

[0047] Alternatively or in addition, the radiation emitting element may be a light-emitting diode (LED), specifically a LED emitting light that is at least partially located in the infrared spectral range. Alternatively or in addition, a LED emitting light that is illuminating a luminescent material, specifically a phosphor, for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range. 240305WO01

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[0049] The illumination light may have a spectral range at least partially located in the near-infrared spectral range, specifically in the spectral range from 1 to 3 pm, preferably from 1.3 to 2.5 pm, more preferably from 1.5 to 2.2 pm.

[0050] The term “beam path” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a trajectory or a route taken by a beam of light. The trajectory or the route taken by the beam of light may be through space and / or at least one optical component. The first beam path may be different from the second beam path, particularly in a manner that at least a portion of their trajectory or route differ.

[0051] The first beam path is configured for light propagating along the first beam path passing at least one sample interface of the spectrometer device. By passing the sample interface, the first light may leave the spectrometer device. The first beam path may be configured for directing the first light, specifically first illumination light, onto an object. Thereby, the first light may interact with the object in a manner that first detection light may be generated. When the first light interacted with the object, the first light might propagate to the detector and generate at least one detector signal.

[0052] The term “sample interface” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary surface, such as measurement surface, at which an object is intended to interact with an optical measurement system, such as the spectrometer device. The measurement surface may be a measurement plane. For interacting with the object, the spectrometer device may emit the illumination light, particularly in a manner that the object generates the detection light. In addition, the spectrometer may receive the detection light. Particularly to allow the interaction with the object as intended, the sample interface may define a measurement pose of the object. When the object assumes the measurement pose, particularly as defined by the sample interface, at least one of: receiving the illumination light by the object and, thereby, generating the detection light is per-formed in a manner as intended, such as that when the object assumes the measurement pose, the signal-to-noise ratio of the spectrometer device is increased.

[0053] The term “measurement pose” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a relative posi- 240305WO01

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[0055] tion and / or orientation of the object relative to the sample interface, which is intended to be assumed during the spectral measurement, particularly to allow an interaction between the spectrometer device and the object as intended, such as intended by the setup and / or arrangement of the components of the spectrometer device.

[0056] The second beam path is configured for light propagating along the second beam path without passing the at least one sample interface of the spectrometer device. By not passing the sample interface, the second light may remain in the spectrometer device. When the second light interacted with the internal calibration target, the second light might may travers to the detector and generate the at least one detector signal S2(I2).

[0057] An internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target. The at least one known optical characteristic may be or may comprise a known reflectivity of the internal calibration target.

[0058] The term “calibration target” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a reference object having known characteristics, such as a predetermined and / or a predefined, describing the interaction with light. The calibration target may be used to calibrate the spectrometer device.

[0059] The term “internal calibration target” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to at least one calibration target integrated in the spectrometer device, in particular in the second beam path of the spectrometer device. Specifically, the internal calibration target may be configured for interacting with the second light, such as the second illumination light, in the second optical path in a predetermined or pre-defined manner. The internal calibration target may be configured for receiving the second light emitted from the second light emitting element and transferring the second light via the second beam path onto the detector. In particular, the internal calibration target may be configured for ensuring that the illumination light emitted from the second light emitting element propagates via the second beam path to the wavelength selective element without passing the sample interface, e.g. by interacting with the second illumination light, such as by reflecting and / or scattering and / or filtering and / or directing, the second light onto the optical filter. 240305WO01

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[0061] The internal calibration target may comprise at least one diffusive reflective surface. The term “diffuse reflective surface” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a surface configured for scattering incident light at a plurality of different angles, e.g. in ideal case Lambertian reflection. The internal calibration target may have diffusive scattering properties and a reflectance not equal to zero. Specifically, the internal calibration target may function as a diffuse mirror. The internal calibration target may comprise a surface roughness configured for generating a Lambertian reflection profile. The surface roughness may be selected such that a specular reflection on the surface has a Lambertian profile due to a ratio of the wavelength of the incident radiation and the surface roughness, thereby creating a “diffuse mirror”. The surface roughness may be selected depending on the wavelength of the impinging light, e.g. such that the reflection (e.g. Fresnel reflection generated by a metal or partial Fresnel and partial diffuse reflection generated by a dielectric material) has a Lambertian profile.

[0062] For example, the internal calibration target comprises one or more of: at least one layer of Polytetrafluoroethylene (PTFE), at least one optical coating, such as a white surface coating, e.g. available from Nextel® Suede coating 3101, a dielectric coating, at least one partially reflective dielectric mirror, at least one metal coating or metal foil comprising one or more of gold, silver, aluminum, chromium, and at least one beam splitter. For example, the internal calibration target may be applied to the substrate by one or more of spray coating, stamping, printing, gluing, at least one squeegee process.

[0063] The substrate may be at least partially covered by the internal calibration target. The internal calibration target may cover 0.1 to 99.9 % of the substrate, specifically 0.5 to 25 % of the substrate, more specifically 1 to 10% of the substrate. For example, 1 to 10 % of the substrate may be covered by the internal calibration target and a rest, e.g. of 99 to 90% may be used for the first optical path for measuring the object.

[0064] The internal calibration target may comprise at least one white reflection element such as a coating, film or foil. The term “white” as used herein 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 to be limited to a special or customized meaning. The term specifically may characterize, without limitation, the reflection of the element, i.e. that the reflection is essentially wavelength independent in the wavelength range of interest, in particular that there are no dominant absorption peaks in the reflection spectrum of the element in the given wavelength range. The term “white reflection element” as used herein is a broad term and is to be given its ordinary and customary meaning to 240305WO01

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[0066] a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a material layer having an at least partially diffusive reflective surface. The white reflection element may provide a diffusive reflective surface. The white reflection element may be semi-transparent at at least one given wavelength range. The wavelength range for which the white reflection element is semi-transparent may be selected such that it matches at least partially the wavelength range of the light source. However, the wavelength range for which the white reflection element may be different from the wavelength range of the light source, e.g. narrower. The white reflection element may be configured for at least partially reflecting and / or partially transmitting incident light. The white reflection element may comprise one or more of at least one layer of Polytetrafluoroethylene (PTFE), at least one optical coating, such as a white surface coating, e.g. a white varnish available from Nextel® Suede coating 3101.

[0067] The white reflection element may be arranged directly on the substrate. The term “arranged directly” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an application without any further element between the substrate and the white reflection element. For example, white reflection element may be coated, e.g. spray coated, on the substrate. However, other processes may be possible such as stamping, printing, gluing, at least one squeegee process and the like.

[0068] The internal calibration target may comprise at least one carrier element via which the white reflection element is arranged onto the substrate. The term “carrier element” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to at least one element and / or layer arranged between two other elements, e.g. the substrate and the white reflection element. The carrier element may be configured for providing at least one supporting function for mounting at least one further element of the internal calibration target onto the substrate. For example, the white reflection element and the carrier element may function together as internal calibration target and / or the carrier element may support the white reflection element. The carrier element may be diffuse reflective in at least one wavelength range. The carrier element may comprise at least one reflection material. The white reflection element may be semi-transparent. The carrier element may be configured for scattering light upon transmission of the white reflection element. Thus, the reflective carrier can increase overall reflectivity. The mounting of the white reflection element onto the carrier element may be performed e.g. using a transparent adhesive, e.g., epoxy glue, or in at least one spray coating (varnish) process. However, other processes are possible. 240305WO01

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[0070] The verb “to detect” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of at least one of determining, measuring and monitoring at least one parameter, qualitatively and / or quantitatively, such as at least one of a physical parameter, a chemical parameter and a biological parameter. Specifically, the physical parameter may be or may comprise an electrical parameter. Consequently, the term “photosensitive detector”, or “detector” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device configured for detecting, i.e. for at least one of determining, measuring and monitoring, at least one parameter, qualitatively and / or quantitatively, such as at least one of a physical parameter, a chemical parameter and a biological parameter. The at least one detector may be configured for generating at least one detector signal, more specifically at least one electrical detector signal, such as an analogue and / or a digital detector signal, the detector signal providing information on the at least one parameter measured by the detector. The detector signal may directly or indirectly be provided by the at least one detector to the evaluation unit, such that the at least one detector and the evaluation unit may be directly or indirectly connected. The detector signals may be used as a “raw” detector signal and / or may be processed or preprocessed before further used, e.g. by filtering and the like. Thus, the at least one detector may comprise at least one processing device and / or at least one preprocessing device, such as at least one of an amplifier, an analogue / digital converter, an electrical filter and a Fourier transformation.

[0071] The at least one detector may be configured for detecting light propagating from the object to the spectrometer device or more specifically to the at least one detector of the spectrometer device. The at least one detector may be configured for determining at least one optical parameter, such as an intensity and / or a power of light by which at least one sensitive area of the detector is irradiated. More specifically, the at least one detector may comprise at least one photosensitive element and / or at least one optical sensor, such as at least one of a photodiode, a photocell, a photosensitive resistor, a phototransistor, a thermophile sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier and a bolometer. The at least one detector, thus, may be configured for generating at least one detector signal, more specifically at least one electrical detector signal, in the above-mentioned sense, providing information on at least one optical parameter, such as the power and / or intensity of light by which the detector or a 240305WO01

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[0073] sensitive area of the detector is illuminated. The at least one detector may be a Lead Sulfide (PbS) detector.

[0074] The detector may comprise a plurality of photosensitive elements, wherein each of the photosensitive elements may be configured for generating at least one detector signal for deriving the spectral information. The plurality of photosensitive elements may be arranged in an array. The term “array” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a series of optical sensors which may, preferably, be arranged in a single line as a one-dimensional matrix along the length of the length variable filter or in more than one line, especially in two, three, or four parallel lines, in form of a two-dimensional matrix, in particular, in order to receive most of the intensity of the incident light as possible. Thus, a number N of photosensitive elements in one direction may be higher compared to a number M of photosensitive elements in a further direction such that the one-dimensional 1 x N matrix or a rectangular two-dimensional M x N matrix may be obtained, wherein M < 10 and N > 10, preferably N > 20, more preferred N > 50. In addition, the matrixes may also be placed in a staggered arrangement.

[0075] The plurality of photosensitive elements may be sensitive to differing, particularly not overlapping, wavelength intervals. Particularly consequently, a first photosensitive element may detect light within a first wavelength range and a second photosensitive element may detect light within a second wavelength range, wherein the first and the second wavelength range are different from each other, particularly in a manner that wavelength ranges do not overlap. There may be a third photosensitive elements having a further different, particularly not overlapping, wavelength range, and so on.

[0076] The spectrometer device further may comprise at least one wavelength-selective element, wherein the wavelength-selective element is disposed in at least one of:

[0077] - the at least one first beam path;

[0078] - the at least one second beam path.

[0079] The at least one the wavelength-selective element may be configured and / or may be arranged in a manner that any photosensitive element of the plurality of photosensitive elements is exposed to an individual spectral range of light.

[0080] The method comprises the following steps: 240305WO01

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[0082] 1) receiving a dependency I1(U1) of a radiation intensity I1of a first light emitting element of the spectrometer device depending on a first forward voltage U1applied for driving the first light emitting element;

[0083] 2) receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element of the spectrometer device depending on a second forward voltage U2applied for driving the second light emitting element;

[0084] 3) determining a function b between the dependency I1(U1) and the dependency I2(U2), wherein

[0085] b =

[0086] 12(U2)’

[0087] and determining a function f1(U1) by solving the function b for U2and / or determining a function f2(U2) by solving the function b for U1in a manner that

[0088] f1(U1) = U2and

[0089] f2(U2) = U1;

[0090] 4) determining at least one, two or any one of the following functions by using the function

[0091]

[0092] and / or the function f2cu2y.

[0093] D(U1) =

[0094] R1(U1) / R2(f1(U1))

[0095] D(U2) = R1(f2(U2)) / R2(U2)

[0096] R2(u2) ’

[0097] D*(U1) = O1(U1) / O2(f1(U1)) and

[0098] O1(f2(U2))

[0099]

[0100] O2(u2) ’

[0101] wherein R1(U1) and R1(f2(U2)) are a detector signal generated by first light propa- gating along the first beam path measured while a reference calibration target is arranged at the sample interface; wherein R2(f1(U1)) and R2(U2) are a detector signal generated by second light propagating along the second beam path measured while the reference calibration target is arranged at the sample interface; wherein O1(U1) and O1(f2(U2)) are a detector signal generated by first light propagating along the first beam path measured while the sample interface is free, preferably of an object and / or the reference calibration target; wherein O2(U2) and O2(f1(U1)) is a detector signal generated by second light propagating along the second beam path measured while the sample interface is free, preferably of an object and / or the reference calibration target. 240305WO01

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[0103] As already indicated, the method comprises receiving a dependency I1(U1) of a radiation intensity I1of a first light emitting element of the spectrometer device depending on a first forward voltage U1applied for driving the first light emitting element.

[0104] The term “to drive” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of providing electrical power to another device, such as a forward voltage. For driving a light emitting element, the spectrometer device may comprise a driving unit configured for providing the forward voltage. Consequently, the term “driving unit” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device or a combination of devices configured for providing one or both of at least one control parameter and / or electrical power to another device, such as, in the present case, to the first light emitting element and / or the second light emitting element.

[0105] The term “dependency” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a relationship in which a value is determined or influenced by changes in the variable. Altering said variable may affect the value according to some rule or function. The dependency may be described by said rule or function. The function may be a mathematical function.

[0106] The dependency I1(U1) may determine the radiation intensity I1emitted by the first light emitting element as a function of the first forward voltage U1. Typically, the dependency may determine a specific radiation intensity I1for each specific first forward voltage U1of a plurality of differing first forward voltages U1. Thereby, for a first specific first forward voltage U1a first specific radiation intensity I1may be determined by the dependency I1(U1) and for a second specific first forward voltage U1a second specific radiation intensity I1may be determined by the dependency I1(U1).

[0107] The dependency I1(U1) may be determined by performing a polynomial fit of the n-th order, preferably wherein n = 2,

[0108] n

[0109] = ∑ m1,iU1,faci

[0110]

[0111] i=0

[0112] Performing the fit may be a step of the method. 240305WO01

[0113] - 15 -

[0114] The dependency / 2(^2) may be determined by performing a polynomial fit of the n-th order, preferably wherein n = 2,

[0115] I2(U2) = ∑m2,iU2i.

[0116]

[0117] i=0

[0118] Performing the fit may further be a step of the method.

[0119] When I1(U1)

[0120]

[0121] = ∑i=0nm1,iU1iand I2(U2) = ∑i=0nm2,iU2iit holds that

[0122]

[0123] In case of n=1 and two light emitting elements that show a linear but not necessarily parallel behavior, it holds that:

[0124] m1,0+ m1,1U1= b · (m2,0+ m2,1U2); and

[0125] m1,0+ m1,1U1− b · m2,0

[0126] = f1(U1) = U2.

[0127] b · m2,1

[0128] b(m2,0+ m2,1U2) − m1,0

[0129] = f2(U2) = U1

[0130]

[0131] In case of n=2 and two light emitting elements that show a quadratic and not parallel behavior, it holds that:

[0132] m1,0+ m1,1U1+ m1,2U12= b · (m2,0+ m2,1U2+ m2,2U22);

[0133] ∓√(b(−4 · b · m2,0· m2,2+ b · m2,12+ 4 · (m2,2· m1,0+ m2,2· m1,1+ m2,2· m1,2· U12))) − b · m2,1 / 2b · m2,2

[0134] ∓√(4m1,2(b(m2,2U22+ m2,0+ m2,1U2) − m1,0+ m1,12) − m1,1

[0135] U1= f2(U2) =

[0136]

[0137] 2 m1 2

[0138] Receiving the dependency I1(U1) may comprise at least one of:

[0139] - measuring the dependency I1(U1) by performing a measurement, preferably by at least one of:

[0140] o measuring the intensity I1when applying a plurality of different voltages U1

[0141]

[0142] o measuring the intensity I1and the voltage U1when applying the same current at different temperatures.

[0143] U1and U2may be functions of 7^ and T2, specifically U1(T1) and U2(T2) and, therefore, it holds that I1(U1(T1)) and I2(U2(T2)) are also functions of T1and T2, wherein T±and T2are Temperatures. 240305WO01

[0144] - 16 -

[0145] Measuring the dependency I1(U1) by performing a measurement, may be performed in a factory calibration.

[0146] The term “factory calibration” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a calibration that may be performed at a facility. The factory calibration may be performed by a manufacturer and / or a specialized technician. The factory calibration may not be performed by a consumer. The factory calibration may not be an online calibration that is being performed in the field by the consumer.

[0147] As already indicated, the method comprises receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element of the spectrometer device depending on a second forward voltage U2applied for driving the second light emitting element.

[0148] The dependency I2(U2) may determine the radiation intensity I2emitted by the second light emitting element as a function of the second forward voltage U2. Typically, the dependency may determine a specific radiation intensity I2for each specific second forward voltage U2of a plurality of differing second forward voltages U2. Thereby, for a first specific second forward voltage U2a first specific radiation intensity I2may be determined by the dependency I2(U2) and for a second specific second forward voltage U2a second specific radiation intensity I2may be determined by the dependency I2(U2

[0149] Receiving the dependency I2(U2) may comprise at least one of:

[0150] - measuring the dependency I2(U2) by performing a measurement; preferably by at least one of:

[0151] o measuring the intensity I2when applying a plurality of different voltages U2, o measuring the intensity I2and the voltage U2when applying the same current at different temperatures.

[0152] Measuring the dependency / 2(^2) by performing a measurement, may be performed in a factory calibration.

[0153] As already indicated, the method determining at least one of the following functions:

[0154] D(U1) =

[0155] D(U1) =

[0156]

[0157] 240305WO01

[0158] - 17 -

[0159] D(U2) = R1(f2(U2)) / R2(U2)

[0160] R2(U2) ’

[0161] and

[0162] O2(f1(U1))

[0163] O1(f2(U2))

[0164]

[0165] o2(u2) ’

[0166] wherein R1(U1) and R1(f2(U2)) are a detector signal generated by first light propagating along the first beam path measured while a reference calibration target is arranged at the sample interface; wherein R2(f1(U1)) and R2(U2) are a detector signal generated by second light propa-gating along the second beam path measured while the reference calibration target is arranged at the sample interface; wherein

[0167]

[0168] O1(U1) and O1(f2(U2)) are a detector signal generated by first light propagating along the first beam path measured while the sample interface is free; wherein O2(U2) and O2(f1(U1)) is a detector signal generated by second light propagating along the second beam path measured while the sample interface is free.

[0169] While the sample interface is free, an open port measurement may be performed. The term “open port measurement” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a measurement being performed when the sample interface is free of any object.

[0170] The term “reference calibration target” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a specific calibration target configured to be placed at the sample interface outside of the spectrometer device. The definitions given for the internal calibration target apply accordingly for the reference calibration target.

[0171] As already indicated, the method comprises determining a function b between the dependency I1(U1) and the dependency I2(U2)

[0172] The function b may be determined by dividing the dependency I1(U1) and the dependency I2(U2); °rvice versa. The function b may be a constant that is independent of the first forward voltage U1and the second forward voltage U2. 240305WO01

[0173] - 18 -

[0174] The at least one of the steps 1), 2) and 3) may be performed independent and / or before an assembly of the spectrometer device. The steps 1) and 2) may be performed for each light emitting element independently. The term “independent” may refer to the steps 1), 2) and 3) being performed in isolation, without relying on and / or being influenced by their role in the assembled spectrometer device. Measuring the at least one of the detector signals R1(U1), R2(U2),

[0175]

[0176] and O2(U2), specifically for step 4), may be performed when the spectrometer device is assembled. The detector signals R1(U1), R1(f2(U2)),

[0177]

[0178] may be measured in order to determine R1(f2(U2)), R2(f1(U1)), O1(f2(U2)) and / or O2(f1(U1)). Thereby, the specifics of the spectrometer design of an individual spectrometer may be accounted for.

[0179] Step 4) may be performed when the spectrometer device is assembled. The spectrometer device may be configured in a manner that the first beam path is configured for the first light propagating onto a detector of the spectrometer device along the first beam path in a manner that the first light passes the at least one sample interface of the spectrometer device. The spectrometer device may be configured in a manner that the second beam path is configured for the second light propagating onto the detector of the spectrometer device along the second beam path in a manner that the second light is not passing the at least one sample interface of the spectrometer device.

[0180] An emittance spectrum of the first light emitted by the first light emitting element may equal an emittance spectrum of the second light emitted by the second light emitting element. The second light emitted by the second light emitting element may have a smaller bandwidth than the first light emitted by the first light emitting element.

[0181] The first light emitting element may be driven in a polarization multiplexing mode at at least one first polarization. The term “polarization multiplexing mode” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a procedure for multiplexing a plurality of signals carried by light waves, allowing a plurality of channels of information to be transmitted on the same carrier by using waves of different polarization states. The evaluation unit may be configured for assigning at least one detector signal to the first beam path, e.g. the first light emitting element, or the second beam path, e.g. the first light emitting element, by evaluating the polarization of the detected first light and the polarization of the detected second light. 240305WO01

[0182] - 19 -

[0183] The second light emitting element may be driven in a polarization multiplexing mode at one or more second polarizations, particularly wherein the at least one first polarization is different than the one or more second polarizations.

[0184] The first light emitting element may be driven in a frequency multiplexing mode at at least one first frequency. The term “frequency multiplexing mode” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a procedure for multiplexing a plurality of signals carried by light waves, allowing a plurality of channels of information to be transmitted on the same carrier by using waves of different frequency states. The evaluation unit may be configured for assigning at least one detector signal to the first beam path, e.g. the first light emitting element, or the second beam path, e.g. the first light emitting element, by evaluating the frequency of the detected first light and the frequency of the detected second light.

[0185] The second light emitting element may be driven in a frequency multiplexing mode at one or more second frequencies, particularly wherein the at least one first frequency is different than the one or more second frequencies. The one or more second frequencies may comprise a first second frequency that is smaller than the first frequency, and the one or more second frequencies may comprise a second second frequency that is larger than the first frequency.

[0186] The calibration target may be at least one of: at least one beam splitter; at least one optical grating. A material of the calibration target may be or may comprise at least one of: at least one layer of Polytetrafluoroethylene (PTFE), at least one optical coating, such as a white surface coating or at least one color coating, e.g. a near infra-red reflecting color coating, at least one dielectric coating, at least one partially reflective dielectric mirror, at least one metal coating or metal foil comprising one or more of gold, silver, aluminum and chromium.

[0187] In a further aspect, a method for operating a spectrometer device for obtaining at least one item of spectral information on at least one object is disclosed. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0188] The steps of the method for operating a spectrometer device may be performed in the given order. A different order, however, may also be feasible. Further, two or more of the method steps may be performed simultaneously. Thereby, the method steps may at least partly overlap in time. Further, the method steps may be performed once or repeatedly. Thus, one or more or 240305WO01

[0189] - 20 -

[0190] even all of the method steps may be performed once or repeatedly. The method may comprise additional method steps, which are not listed herein.

[0191] The method for operating a spectrometer device may be a computer-implemented method. Alternatively or in addition, at least one of the method steps, preferably any one of the method steps, which involve the use of an evaluation unit, may be performed by using a device comprising at least one processor for executing the steps. The term "computer implemented method" as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a method, which involves at least one apparatus, specifically a computer, or a plurality of apparatus, particularly connected via a computer network. The plurality of apparatus may be connected, particularly for transmitting data, via a network by using at least one connection interface at any one of the apparatuses of the plurality of apparatus. The computer-implemented method may be implemented as at least one computer program that may be provided on a storage medium carrying the computer program, whereby at least one of the steps of the computer-implemented method are performed by using the at least one computer program. Preferably any one of the steps may be performed using the at least one computer program. Alternatively, the at least one computer program may be accessible by an apparatus which may be adapted for performing the method via a network, such as via an inhouse network, via internet, or via a cloud. With particular regard to the present invention, the present method can, thus, be performed on a programmable apparatus, which is configured for this purpose, such as by providing a computer program, which is configured for such a purpose.

[0192] The term “spectral information”, also referred to as “spectroscopic information” or as “item of spectral information”, as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an item of information, e.g. on the at least one object and / or radiation emitted by the at least one object, characterizing at least one optical property of the object, more specifically at least one item of information characterizing, e.g. qualifying and / or quantifying, at least one of a transmission, an absorption, a reflection and an emission of the at least one object. As an example, the at least one item of spectral information may comprise at least one intensity information, e.g. information on an intensity of light being at least one of transmitted, absorbed, reflected or emitted by the object, e.g. as a function of a wavelength or wavelength sub-range over one or more wavelengths, e.g. over a range of wavelengths. Specifically, the intensity information may correspond to or be derived from the signal intensity, specifically the electrical signal, recorded by the spectrometer device with respect to a wavelength or a range of wavelengths of the spectrum. 240305WO01

[0193] - 21 -

[0194] The “object” may, generally, be an arbitrary body, chosen from a living object and a non-living object. Thus, as an example, the at least one object may comprise one or more articles and / or one or more parts of an article, wherein the at least one article or the at least one part thereof may comprise at least one component which may provide a spectrum suitable for investigations. Additionally or alternatively, the object may be or may comprise one or more living beings and / or one or more parts thereof, such as one or more body parts of a human being, e.g. a user, and / or an animal.

[0195] The method comprises the following steps:

[0196] 1. emitting first light along a first beam path onto a detector of the spectrometer device by using at least one first light emitting element of the spectrometer device in order to generate at least one first detector signal

[0197]

[0198] at a known first forward voltage U1applied for driving the first light emitting element; wherein the spectrometer device is configured in a manner that the first beam path is configured for first light propagating along the first beam path passing at least one sample interface of the spectrometer device; wherein the at least one object is arranged on the at least one sample interface in a manner that first light interacts with the at least one object, particularly in a manner that first detection light is generated that is received by the detector;

[0199] 2. emitting second light along a second beam path onto the detector by using at least one second light emitting element of the spectrometer device in order to generate at least one second detector signal S2(I2) at a known second forward voltage U2applied for driving the second light emitting element; wherein the spectrometer device is configured in a manner that the second beam path is configured for second light propagating along the second beam path without passing the at least one sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target, particularly in a manner that second detection light is generated that is received by the detector;

[0200] 3. determining the item of spectral information on the object by evaluating the at least one first detector signal

[0201]

[0202] and the at least one second detector signal S2(I2) by using an evaluation unit, wherein evaluating the at least one first detector signal and the at least one second detector signal S2(I2) comprises using at least one of the following functions £>(t i); D U2); Z>*(I / i) and / F([ / 2), wherein the functions £>(t i); D U2); ZT(t i) and / F([ / 2) are determined by performing a method for 240305WO01

[0203] - 22 -

[0204] calibrating a spectrometer device according to any one of the preceding claims referring to a method for calibrating a spectrometer device.

[0205] As further used herein, the term “detection light” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to light that is generated by the object, particularly generated in an interaction of the illumination light with the object. The light may interact with the object by scattering, reflecting and / or transmitting. The detection light may be first light and / or second that is reflected and / or scattered back through the sample interface to the at least one detector. At least a portion of the illumination light may be transmitted and / or absorbed by the object in a manner that it is not detected by the at least one detector.

[0206] Typically, the item of spectral information, specifically an absorbance a, is determined via a logarithm of the reflectance r. The reflectance r may be determined from an object measurement Si, a reference calibration target measurement R and an open port measurement

[0207]

[0208] by using 1 Sr- 01

[0209] a

[0210]

[0211] = °8r =

[0212] In this case, the determination of the absorbance a requires at least three subsequent measurements with a first light emitting element. During these measurements the temperature of the light emitting element may change. Said temperature change may cause a change in the forward voltage U applied to the light emitting element in order to drive the light emitting element.

[0213] A dependency I1(U1) of a radiation intensity I1of the first light emitting element of the spectrometer device depending on a first forward voltage U1may be used to correct for environmental changes, specifically said temperature change resulting from subsequent measurements. In the subsequent measurements, the temperature of the light emitting element may typically increase. Said temperature increase may lead to a decrease of the forward voltage U1.

[0214] This effect may be corrected by accounting for the change of the radiation intensity caused by the change in the forward voltage U1by using the dependency I1(U1).

[0215] In the present case, the spectrometer device comprises a first light emitting element and a second light emitting element. The second light emitting element may be used for an online calibration. This online calibration is, typically, used to reduce the amount of subsequent measurement, such that no reference calibration target measurement R and an open port measurement is required. For this purpose, two functions may be calibrated in a factory calibration, namely 240305WO01

[0216] - 23 -

[0217] D =Rl / g2=Rl / S2and

[0218]

[0219] = % = %

[0220] The item of spectral information on the object may then be determined by using the equation S1- D* - S2

[0221] a = —log -.

[0222]

[0223] 5(D - £)*) ■ S2

[0224] The detector signals Si and S2are generated while the object is arranged at the sample interface. The detector signals

[0225]

[0226] and 02aregenerated while no object is arranged at the sample interface in order to perform an open port measurement. The detector signals R and R2are generated while a reference calibration target is arranged at the sample interface in order to perform an open port measurement. The index 1 indicates that the respective detector signals is generated by first light emitted by the first light emitting element along the first beam path. The index 2 indicates that the respective detector signals is generated by second light emitted by the second light emitting element along the second beam path.

[0227] For a correction of the change in the temperature, both radiation intensities

[0228]

[0229] and I2of both light emitting elements may have to be characterized in a calibration process. In the calibration process that is described by the method for calibrating the spectrometer device, the radiation intensities I1and I2may be measured depending on the forward voltages U1, U2by using at least one external detector. As already indicated, the spectrometer device may not being assembled at this stage for the characterization of both light emitting elements. The measurements required for the calibration process may be performed under at least one controlled environmental condition, such as a controlled temperature, humidity and so on.

[0230] To account for spectrometer device specific characteristics two additional functions may have to be calibrated, namely

[0231] D(U1) =

[0232] Wi, t / 2) and

[0233] R2(JJ2-) S2(L72)

[0234]

[0235] O2([ / 2) s2(u2y

[0236] These functions may again be measured in calibration process described by the method for calibrating the spectrometer device under controlled conditions.

[0237] By using the functions D(U1, U2), D*(U1, U2) the following functions may be calculated:

[0238] D(U1) =

[0239] D(U1) =

[0240] Rz i y 240305WO01

[0241] - 24 -

[0242] W 2)).

[0243] £»([ / 2) =

[0244] R2(U2) ’

[0245] and

[0246] O2(A(t / i))

[0247] O1(f2(U2))

[0248]

[0249] O2(u2) ’

[0250] As already indicated, the item of spectral information on the object may be, typically, determined by using the equation

[0251] ni ri, _. SdUj -DWi, U2)S2(U2)

[0252]

[0253] n 2) ogm u2) -oyiy, u2y -s2(u2y

[0254] In this case

[0255] Q1W

[0256] and

[0257] O2(U2) S2(U2)

[0258] DCiy,

[0259]

[0260] R2(U2) s2(u2y

[0261] As already indicated, the detector signals S (Ly) and S2(I2) are generated while the object is arranged at the sample interface. The detector signals Oi(t / i) and O2([ / 2) are generated while no object is arranged at the sample interface in order to perform an open port measurement. The detector signals R^ Ui) and R2U2) are generated while a reference calibration target is arranged at the sample interface in order to perform an open port measurement. The index 1 indicates that the respective detector signals is generated by first light emitted by the first light emitting element along the first beam path. The index 2 indicates that the respective detector signals is generated by second light emitted by the second light emitting element along the second beam path.

[0262] Herein, the item of spectral information on the object may be determined by using at least one of equations

[0263] ni. _, syy2(u2y - p\u2y s2(u2)

[0264]

[0265] 2) 09(P(U2) - P\U2)y S2(U2) ■

[0266] As already indicated

[0267] D(U1) =

[0268] D(UJ =

[0269] R2(f1(U1))

[0270] W 2)).

[0271] D(U2) =

[0272]

[0273] R2(U2) ’ 240305WO01

[0274] - 25 -

[0275] Oi(Oi)

[0276] and

[0277] O2(A(OI))

[0278] W2))

[0279]

[0280] O2(O2) ■

[0281] The term “to evaluate”, as used herein, 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of processing at least one first item of information in order to generate at least one second item of information thereby. Consequently, the term “evaluation unit”, as used herein, 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device or a combination of devices configured to evaluate or process at least one first item of information, in order to generate at least one second item of information thereof. Thus, specifically, the evaluation unit may be configured for processing at least one input signal and to generate at least one output signal thereof. The at least one input signal, as an example, may comprise at least one detector signal provided directly or indirectly by the at least one photosensitive detector.

[0282] As an example, the evaluation unit may be or may comprise 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 of computers, digital signal processors (DSP), field programmable gate arrays (FPGA) preferably one or more microcomputers and / or microcontrollers. Additional components may be comprised, such as one or more preprocessing devices and / or data acquisition devices, such as one or more devices for receiving and / or preprocessing of the detector signals, such as one or more AD-converters and / or one or more filters. Further, the evaluation unit may comprise one or more data storage devices. Further, the evaluation unit may comprise one or more interfaces, such as one or more wireless interfaces and / or one or more wire-bound interfaces.

[0283] ln a further aspect, a method for calibrating a spectrometer device is disclosed for obtaining items of calibration information cRand c0. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0284] The steps of the method may be performed in the given order. A different order, however, may also be feasible. Further, two or more of the method steps may be performed simultaneously. 240305WO01

[0285] - 26 -

[0286] Thereby, the method steps may at least partly overlap in time. Further, the method steps may be performed once or repeatedly. Thus, one or more or even all of the method steps may be performed once or repeatedly. The method may comprise additional method steps, which are not listed herein.

[0287] The items of calibration information cRand c0are used in object measurement in order to determine at least one item of spectral information, such as a(S1, S2, UltU2) =

[0288] -log,.-1 D. -2)- >, on an object, wherein the spectrometer device comprises:

[0289] D U1, U2)—D U1, U2))‘S2

[0290] - at least one sample interface, wherein the sample interface is configured for defining a measurement pose of at least one sample outside of the spectrometer device;

[0291] - at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0292] - at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one sample,

[0293] - at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target.

[0294] The method comprises the following steps:

[0295] 1) receiving a dependency I1(U1) of a radiation intensity I1of the first light emitting element of the spectrometer device depending on a first forward voltage U1applied for driving the first light emitting element;

[0296] 2) receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element of the spectrometer device depending on a second forward voltage U2applied for driving the second light emitting element;

[0297] 3) performing a first measurement of R̄1, R̄2for a known first forward voltage Ū1and a known second forward voltage Ū2a second measurement of Ō1, Ō2for a known first forward voltage Ū1and a known second forward voltage Ū2when the spectrometer is assembled, wherein R̄1is a detector signal generated by first light propagating along the first beam path measured while a reference calibration target, 240305WO01

[0298] - 27 -

[0299] being used as the at least one sample, is arranged at the at least one sample interface of the spectrometer device, wherein R2is a detector signal generated by second light propagating along the second beam path measured while the reference calibration target is arranged at the at least one sample interface; wherein is a detector signal generated by first light propagating along the first beam path measured while the at least one sample interface is free, wherein O2is a detector signal generated by second light propagating along the second beam path measured while the at least one sample interface is free;

[0300] 4) determining the items of calibration information cRand c0by using

[0301] Ri

[0302] — — Cp *; and

[0303]

[0304] R2^2 (^2)

[0305] Oi _ / i(Oi)

[0306] = —CO * z= v

[0307]

[0308] O2I2(U2)

[0309] wherein the determined cRand c0are constants with respects to the first forward voltage U1and the second forward voltage U2.

[0310] Ū1, Ū2, Ū1and / or Ū2may be known by measurement. The radiation intensity I1is the intensity or the optical output emitted from the light emitting element. The radiation intensity I1is independent of spectrometer-internal-transfer factors. In contrast,

[0311]

[0312] S1, R1and are signals / intensities received by the detector via the first beam path. This also applies to S2, I2, R2and O2.

[0313] The behavior of the first and second light emitting elements, specifically the dependencies or functions I1(U1) and I2(U2), may be known from manufacturer specifications and / or factory calibration. I1(U1) and I2(U2) denote the radiation intensity or optical output of the first and second light emitting elements as a function of their respective forward voltages, exclusive of spectrometer-internal transfer factors such as optical paths, wavelength-selective elements, detector responsivity and electronics. The measured detector signals depend on these source characteristics and on spectrometer-internal transfer factors. The calibration method accounts for the spectrometer-internal transfer factors by two constant calibration parameters, cRand c0. These parameters are determined from the assembled-device measurements using the reference calibration target and the open-port measurements, thereby minimizing calibration effort. Because cRand c0are constant with respect to U1and U2, the required measurements can be performed under differing environmental conditions. 240305WO01

[0314] - 28 -

[0315] At least one of the steps 1), 2) may be performed independent of an assembly of the spectrometer device. I1(U1) and I2(U2) may be linear functions and may each satisfy I1(0) = I2(0) = 0. In this case = A * U1 / U2and cR= cR* A; and c0= c0* A.

[0316]

[0317] I2(U2) U2R R ’ U U

[0318] A is typically a constant with respect to the forward voltages U1and U2. In a further aspect, a method for operating a spectrometer device for obtaining at least one item of spectral information on at least one object is disclosed. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0319] The steps of the method may be performed in the given order. A different order, however, may also be feasible. Further, two or more of the method steps may be performed simultaneously. Thereby, the method steps may at least partly overlap in time. Further, the method steps may be performed once or repeatedly. Thus, one or more or even all of the method steps may be performed once or repeatedly. The method may comprise additional method steps, which are not listed herein.

[0320] The spectrometer device comprises:

[0321] - at least one sample interface, wherein the sample interface is configured for defining a measurement pose of the at least one sample outside of the spectrometer device;

[0322] - at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0323] - at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one sample,

[0324] - at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target.

[0325] The method comprises the following steps:

[0326] 1. emitting first light along a first beam path onto a detector of the spectrometer device by using at least one first light emitting element of the spectrometer device in 240305WO01

[0327] - 29 -

[0328] order to generate at least one first detector signal S1at a known first forward voltage U1applied for driving the first light emitting element; wherein the spectrometer device is configured in a manner that the first beam path is configured for first light propagating along the first beam path passing at least one sample interface of the spectrometer device; wherein the at least one object being used as at least one sample is arranged on the at least one sample interface in a manner that first light interacts with the at least one object;

[0329] 2. emitting second light along a second beam path onto the detector by using at least one second light emitting element of the spectrometer device in order to generate at least one second detector signal S2at a known second forward voltage U2applied for driving the second light emitting element; wherein the spectrometer device is configured in a manner that the second beam path is configured for second light propagating along the second beam path without passing the at least one sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target;

[0330] 3. determining the item of spectral information on the object by using a at least one evaluation unit and by using

[0331] afS^ U^ Uj = -log-, - - -V J,

[0332]

[0333] wherein

[0334] r~ ~ A 4(^1)

[0335] C / 2) —CR *. zry A Jar*d

[0336] r~ ~ A 4(^1)

[0337]

[0338] v J / 2(t / 2)

[0339] U1and / or U2may be known by measurement. The items of calibration information cRand c0may be determined by performing a method for calibrating a spectrometer device as elsewhere disclosed herein.

[0340] Typically, the item of spectral information, specifically the absorbance a, is dependent from the object signal Si, a reference calibration target signal R and an open port signal by using 240305WO01

[0341] - 30 -

[0342] S1W - Q1W

[0343] a(C / i) = -log

[0344]

[0345] RM - Specifically, the absorbance can be written in the form

[0346] Si(t / i) -^®|s2([ / 2)

[0347] aCU,, u2) = -logvrTrn - n ari -

[0348]

[0349] More specifically, the absorbance can be written in the form

[0350] SM-D U1, U2) -S2U2)

[0351] a U^Uz) = -log

[0352] DiUi. U,) - D^UM) ■ S2(I2)

[0353] wherein

[0354] D(U1) =

[0355] Ddhm

[0356] s2(.u2y

[0357] QiW

[0358]

[0359] s2(u2y

[0360] Since the at least one second beam path comprises an internal calibration target and does not interact with a sample on the sample interface, it may hold that the ratios

[0361]

[0362] and

[0363]

[0364] =01Even further, it may even hold that R2([ / 2) = S2(I2) = O2U2y

[0365]

[0366] Specifically, the absorbance a, is

[0367] s±m i2m

[0368] c

[0369] s2m hm0

[0370] a(Ui> U2~) = -log

[0371] (.CRCO)

[0372] More specifically, the absorbance a, is determined by measuring at least one forward voltage U1together with at least one detector signal 5^ and by measuring at least one forward voltage U2together with at least one detector signal S2, such that

[0373] Si ^2(^2)

[0374] a^Sz, Ultu = -log.

[0375]

[0376] If I-LCU- and I2(U2) are linear functions and satisfy ^(0) = / 2(0) = 0, then

[0377]

[0378] = m1* U1and ^2(^2)= m2 * U2.

[0379] In this case 240305WO01

[0380] - 31 -

[0381] z~ ~ x h(Ul) U1

[0382] v 7i2(u2) U2

[0383] ~ A h(Ul) U1

[0384] D’-fUi, U2} = c0* = c0* A *

[0385]

[0386] v 7 / 2(t / 2) u2with the constant A = m1 / m2. Further in this case, the absorbance a is

[0387] ~ ~ ~ ~ s uc°

[0388] a{S1, S2, U1, U2^ = —log——1„ x.

[0389]

[0390] (CRco)

[0391] In a further aspect, a spectrometer device for obtaining at least one item of spectral information on at least one object by spectroscopic measurement is disclosed. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0392] The spectrometer device comprises:

[0393] a) at least one sample interface, wherein the sample interface is configured for defining a measurement pose of the at least one object outside of the spectrometer device;

[0394] b) at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0395] c) at least one first beam path, wherein the first beam path is configured in a manner that first light propagating along the first beam path passes the sample interface of the spectrometer device and interacts with the at least one object, d) at least one second beam path, wherein the second beam path is configured in a manner that second light propagating along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target,

[0396] e) at least one first light emitting element, wherein the first light emitting element is configured for emitting first light along the first beam path onto the detector; f) at least one second light emitting element, wherein the second light emitting element is configured for emitting second light along the second beam path onto the detector;

[0397] g) at least one evaluation unit, wherein the evaluation unit is configured for obtaining the item of spectral information by using the method for operating the 240305WO01

[0398] - 32 -

[0399] spectrometer device according to any one of the preceding claims referring to a method for operating a spectrometer device.

[0400] In a further aspect, a mobile device is disclosed, wherein the mobile device comprises a spectrometer device as elsewhere disclosed herein. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0401] The term “mobile device” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a mobile electronics de-vice more specifically to a mobile communication device, configured for providing access to at least one telecommunication network, such as a cell phone, smart phone or a wearable. The mobile device may be a portable device.

[0402] The term “portable” as used herein 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 to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the property of at least one object of being moved by human force, such as by a single user. Specifically, the object characterized by the term “portable” may have a weight not exceeding 10 kg, specifically not exceeding 5 kg, more specifically not exceeding 1 kg or even not exceeding 500 g. Additionally or alternatively, the dimensions of the object characterized by the term “portable” may be such that the object extends by no more than 0.3 m into any dimension, specifically by no more than 0.2 m into any dimension. The object, specifically, may have a volume of no more than 0.03 m3, specifically of no more than 0.01 m3, more specifically no more than 0.001 m3or even no more than 500 mm3. In particular, as an example, the portable spectrometer device may have dimensions of e.g. 10 mm by 10 mm by 5 mm. Specifically, the portable spectrometer device may be part of a mobile device or may be attachable to a mobile device, such as a notebook computer, a tablet, a cell phone, such as a smart phone, a smartwatch and / or a wearable computer, also referred to as “wearable”, e.g. a body borne computer such as a wrist band or a watch. In particular, the a weight of the spectrometer device, specifically the portable spectrometer device, may be in the range from 1 g to 100 g, more specifically in the range from 1 g to 10 g.

[0403] In a further aspect, a computer program is disclosed, wherein the computer program comprises instructions which, when the program is executed by a computer, cause the computer to perform the method as elsewhere disclosed herein. The computer program according to the preceding claim, wherein the computer is, preferably an evaluation unit of, the spectrometer device 240305WO01

[0404] - 33 -

[0405] as elsewhere disclosed herein. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0406] In a further aspect, a non-transitory computer-readable storage medium is disclosed, the computer-readable storage medium including instructions that when executed by a computer, cause the computer to perform the method as elsewhere disclosed herein. The non-transitory computer-readable storage medium according to the preceding claim, wherein the computer is, preferably an evaluation unit of, the spectrometer device as elsewhere disclosed herein. For this aspect, reference may be made to any further aspect, particularly any definition, Embodiment or claim given in the context of any further aspect.

[0407] As used herein, the “computer-readable storage medium” specifically may refer to non-transitory data storage means, such as a hardware storage medium having stored thereon computerexecutable instructions. The stored computer-executable instruction may be associate with the computer program. The computer-readable data carrier or storage medium specifically may be or may comprise a storage medium such as a random-access memory (RAM) and / or a readonly memory (ROM).

[0408] As used herein, the terms “have”, “comprise” or “include” or any arbitrary grammatical variations thereof are used in a non-exclusive way. Thus, these terms may both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present. As an example, the expressions “A has B”, “A comprises B” and “A includes B” may both refer to a situation in which, besides B, no other element is present in A (i.e. a situation in which A solely and exclusively consists of B) and to a situation in which, besides B, one or more further elements are present in entity A, such as element C, elements C and D or even further elements.

[0409] Further, it shall be noted that the terms “at least one”, “one or more” or similar expressions indicating that a feature or element may be present once or more than once typically are used only once when introducing the respective feature or element. In most cases, when referring to the respective feature or element, the expressions “at least one” or “one or more” are not repeated, nonwithstanding the fact that the respective feature or element may be present once or more than once. 240305WO01

[0410] - 34 -

[0411] 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 restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way. The invention may, as the skilled person will recognize, be performed by using alternative features. Similarly, features introduced by "in an embodiment of the invention" or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the invention, without any restrictions regarding the scope of the invention and without any restriction regarding the possibility of combining the features introduced in such way with other optional or non-optional features of the invention.

[0412] The method for calibrating a spectrometer device, the method for operating a spectrometer device, the spectrometer device, the mobile device, the computer program and the non-transitory computer-readable storage medium according to the present invention, in one or more of the above-mentioned embodiments and / or in one or more of the embodiments described in further detail below, provide a large number of advantages over known devices and methods of similar kind.

[0413] The present disclosure improves the signal-to-noise ratio of the spectrometer device. Further, the present disclosure minimizes the required calibration measurements. Further, the present disclosure relates to an object measurement scheme allowing to derive an item of spectral information on an object not requiring open port measurements and reference calibration target measurements.

[0414] Summarizing and without excluding further possible embodiments, the following embodiments may be envisaged:

[0415] Embodiment 1: A method for calibrating a spectrometer device for obtaining at least one item of calibration information, wherein the spectrometer comprises at least one sample interface, wherein the sample interface is configured for defining a measurement pose of the at least one object outside of the spectrometer device; at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light; at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one object, at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along 240305WO01

[0416] - 35 -

[0417] the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target, wherein the method comprises the following steps:

[0418] 1) receiving a dependency I1(U1) of a radiation intensity I1of a first light emitting element of the spectrometer device depending on a first forward voltage U1applied for driving the first light emitting element;

[0419] 2) receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element of the spectrometer device depending on a second forward voltage U2applied for driving the second light emitting element;

[0420] 3) determining a function b between the dependency I1(U1) and the dependency I2(U2), wherein

[0421] b.= S il- A(y2)’

[0422] and determining a function f1(U1) by solving the function b for U2and / or determining a function f2(U2) by solving the function b for U1in a manner that

[0423] f1(U1) = U2and

[0424] f2(U2) = U1;

[0425] 4) determining at least one, two or any one of the following functions by using the function

[0426]

[0427] and / or the function f2(u2y.

[0428] D(U1) = R1(U1) / R2(f1(U1));

[0429] R2(f1(U1))

[0430] D(U2) = R1(f2(U2)) / R2(U2);

[0431] R2W2) ’

[0432] D*(U1) = O1(U1) / O2(f1(U1))

[0433] D*(U2) = O1(f2(U2)) / O2(U2)

[0434]

[0435] wherein R1(U1) and R1(f2(U2)) are a detector signal generated by first light propagating along the first beam path measured while a reference calibration target is arranged at the sample interface; wherein R2(f1(U1)) and R2(U2) are a detector signal generated by second light propagating along the second beam path measured while the reference calibration target is arranged at the sample interface; wherein O1(U1) and O1(f2(U2)) are a detector signal generated by first light propagating along the first beam path measured while the sample interface is free; wherein O2(U2) and O2(f1(U1)) is a detector signal generated by second light propagating along the second beam path measured while the sample interface is free. 240305WO01

[0436] - 36 -

[0437] Embodiment 2: The method according to the preceding claim, wherein receiving the dependency I1(U1) comprises at least one of:

[0438] - measuring the dependency I1(U1) by performing a measurement; preferably by at least one of:

[0439] o measuring the intensity I1when applying a plurality of different voltages U1

[0440]

[0441] o measuring the intensity I1and the voltage U1when applying the same current at different temperatures.

[0442] Embodiment 3: The method according to any one of the preceding claims, wherein receiving the dependency l2(U2) comprises at least one of:

[0443] - measuring the dependency I2(U2) by performing a measurement; preferably by at least one of:

[0444] o measuring the intensity I2when applying a plurality of different voltages U2, o measuring the intensity I2and the voltage U2when applying the same current at different temperatures.

[0445] Embodiment 4: The method according to any one of the preceding claims, wherein the function b is determined by dividing the dependency I1(U1) and the dependency I2(U2); or vice versa.

[0446] Embodiment 5: The method according to the preceding claim, wherein the function b is a constant that is independent of the first forward voltage U1and the second forward voltage U2.

[0447] Embodiment 6: The method according to any one of the preceding claims, wherein the at least one of the steps 1), 2) and 3) is performed independent of and / or before an assembly of the spectrometer device.

[0448] Embodiment 7: The method according to any one of the preceding claims, wherein measuring at least one of the detector signals R1(U1), R2(U2), O1(U1) and O2(U2) is performed when the spectrometer device is assembled.

[0449] Embodiment 8: The method according to any one of the preceding claims, step 4) is performed when the spectrometer device is assembled, wherein the spectrometer device is configured in a manner that the first beam path is configured for the first light propagating onto a detector of the spectrometer device along the first beam path in a manner that the first light passes the at least one sample interface of the spectrometer device; wherein the spectrometer device is configured in a manner that the second beam path is configured 240305WO01

[0450] - 37 -

[0451] for the second light propagating onto the detector of the spectrometer device along the second beam path in a manner that the second light is not passing the at least one sample interface of the spectrometer device.

[0452] Embodiment 9: The method according to any one of the preceding claims, wherein an emittance spectrum of the first light emitted by the first light emitting element equals an emittance spectrum of the second light emitted by the second light emitting element.

[0453] Embodiment 10: The method according to any one of the preceding claims 1 to 7, wherein the second light emitted by the second light emitting element has a smaller bandwidth than the first light emitted by the first light emitting element.

[0454] Embodiment 11: The method according to any one of the preceding claims, wherein the first light emitting element is driven in a polarization multiplexing mode at least one first polarization.

[0455] Embodiment 12: The method according to the preceding claim, wherein the second light emitting element is driven in a polarization multiplexing mode at one or more second polarizations, particularly wherein the at least one first polarization is different than the one or more second polarizations.

[0456] Embodiment 13: The method according to any one of the preceding claims, wherein the first light emitting element is driven in a frequency multiplexing mode at least one first frequency.

[0457] Embodiment 14: The method according to the preceding claim, wherein the second light emitting element is driven in a frequency multiplexing mode at one or more second frequencies, particularly wherein the at least one first frequency is different than the one or more second frequencies.

[0458] Embodiment 15: The method according to the preceding claim, wherein

[0459] - the one or more second frequencies comprise a first second frequency that is smaller than the first frequency, and

[0460] - the one or more second frequencies comprise a second second frequency that is larger than the first frequency. 240305WO01

[0461] - 38 -

[0462] Embodiment 16: The method according to any one of the preceding claims, wherein the calibration target is or comprises a material selected from at least one of:

[0463] - at least one layer of Polytetrafluoroethylene (PTFE),

[0464] - at least one optical coating, such as a white surface coating or at least one color coating, e.g. a near infra-red reflecting color coating,

[0465] - at least one dielectric coating, at least one partially reflective dielectric mirror, - at least one metal coating or metal foil comprising one or more of gold, silver, aluminum, chromium, and at least one beam splitter;

[0466] - at least one optical grating.

[0467] Embodiment 17: A method for operating a spectrometer device for obtaining at least one item of spectral information on at least one object, wherein the method comprises the following steps:

[0468] 1. emitting first light along a first beam path onto a detector of the spectrometer device by using at least one first light emitting element of the spectrometer device in order to generate at least one first detector signal

[0469]

[0470] at a known first forward voltage U1applied for driving the first light emitting element; wherein the spectrometer device is configured in a manner that the first beam path is configured for first light propagating along the first beam path passing at least one sample interface of the spectrometer device; wherein the at least one object is arranged on the at least one sample interface in a manner that first light interacts with the at least one object;

[0471] 2. emitting second light along a second beam path onto the detector by using at least one second light emitting element of the spectrometer device in order to generate at least one second detector signal S2(I2) at a known second forward voltage U2applied for driving the second light emitting element; wherein the spectrometer device is configured in a manner that the second beam path is configured for second light propagating along the second beam path without passing the at least one sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target;

[0472] 3. determining the item of spectral information on the object by evaluating the at least one first detector signal and the at least one second detector signal S2(I2) by using an evaluation unit, wherein evaluating the at least one first detector signal and the at least one second detector signal S2(I2) comprises using at least 240305WO01

[0473] - 39 -

[0474] one of the following functions D(U1); D(U2); D*(U1) and D*(U2), wherein the functions D(U1); D(U2); D*(U1) and D*(U2) are determined by performing a method for calibrating a spectrometer device according to any one of the preceding claims referring to a method for calibrating a spectrometer device..

[0475] Embodiment 18: The method according to any one of the preceding claims referring to a method for operating a spectrometer device, wherein the item of spectral information on the object may be determined by using at least one of the equations

[0476] a = -log (S1(U1) - D*(U1) · S2(f1(U1)))

[0477] (D(U1) - D*(U1)) · S2(f1(U1))

[0478]

[0479] a = -log (S1(f2(U2)) - D*(U2) · S2(U2)) / ((D(U2) - D*(U2)) · S2(U2))

[0480] Embodiment 19: A method for calibrating a spectrometer device for obtaining items of calibration information cRand c0, wherein the items of calibration information cRand c0are used in object measurement in order to determine at least one item of spectral information on an object, wherein the spectrometer device comprises:

[0481] - at least one sample interface, wherein the sample interface is configured for defining a measurement pose of at least one sample outside of the spectrometer device;

[0482] - at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0483] - at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one sample,

[0484] - at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target, wherein the method comprises the following steps:

[0485] 1) receiving a dependency I1(U1) of a radiation intensity I1of the first light emitting element of the spectrometer device depending on a first forward voltage U1applied for driving the first light emitting element; 240305WO01

[0486] -40 -

[0487] 2) receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element of the spectrometer device depending on a second forward voltage U2applied for driving the second light emitting element;

[0488] 3) performing a first measurement of R1, R2for a known first forward voltage U1and a known second forward voltage U2a second measurement of O1, O2for a known first forward voltage U1and a second forward voltage U2when the spectrometer is assembled, wherein R1is a detector signal generated by first light propagating along the first beam path measured while a reference calibration target, being used as the at least one sample, is arranged at the at least one sample interface of the spectrometer device, wherein R2is a detector signal generated by second light propagating along the second beam path measured while the reference calibration target is arranged at the at least one sample interface; wherein

[0489]

[0490] is a detector signal generated by first light propagating along the first beam path measured while the at least one sample interface is free, wherein O2is a detector signal generated by second light propagating along the second beam path measured while the at least one sample interface is free;

[0491] 4) determining the items of calibration information cRand c0by using

[0492] >

[0493]

[0494] Oi >

[0495]

[0496] O2I2(u2)

[0497] wherein the determined cRand c0are constants with respects to the first forward voltage U1and the second forward voltage U2.

[0498] Embodiment 20: The method according to the preceding Embodiment, wherein at least one of the steps 1), 2) is performed independent of an assembly of the spectrometer device.

[0499] Embodiment 21: The method according to any one of the preceding two Embodiments, wherein I1(U1) and I2(U2) are linear functions and each satisfy I1(0) = I2(0) = 0 such that

[0500] W > A „ * > t / i

[0501]

[0502] ^2 (^2) ^2

[0503] and

[0504] cR= cR* A; and c0= c0* A. 240305WO01

[0505] -41 -

[0506] Embodiment 22: A method for operating a spectrometer device for obtaining at least one item of spectral information on at least one object, wherein the spectrometer device comprises:

[0507] - at least one sample interface, wherein the sample interface is configured for defining a measurement pose of at least one sample outside of the spectrometer device;

[0508] - at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0509] - at least one first beam path, wherein the first beam path is configured in a manner that first light generated by a first light emitting element propagates along the first beam path, passes the sample interface of the spectrometer device and interacts with the at least one sample,

[0510] - at least one second beam path, wherein the second beam path is configured in a manner that second light generated by a second light emitting element propagates along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target, wherein the method comprises the following steps:

[0511] 1. emitting first light along a first beam path onto a detector of the spectrometer device by using at least one first light emitting element of the spectrometer device in order to generate at least one first detector signal 5^ at a known first forward voltage U1applied for driving the first light emitting element; wherein the spectrometer device is configured in a manner that the first beam path is configured for first light propagating along the first beam path passing at least one sample interface of the spectrometer device; wherein the at least one object being used as at least one sample is arranged on the at least one sample interface in a manner that first light interacts with the at least one object;

[0512] 2. emitting second light along a second beam path onto the detector by using at least one second light emitting element of the spectrometer device in order to generate at least one second detector signal S2at a known second forward voltage U2applied for driving the second light emitting element; wherein the spectrometer device is configured in a manner that the second beam path is configured for second light propagating along the second beam path without passing the at least one sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in the second beam path in a manner that the second light interacts with the at least one internal calibration target; 240305WO01

[0513] - 42 -

[0514] 3. determining the item of spectral information on the object by using a at least one evaluation unit and by using

[0515] = -log-, - - -v },

[0516]

[0517] 2 1 2 / {D(n1,n2') -D'(o1,o2)) -s2

[0518] wherein

[0519] z~ ~ A h(Ui)

[0520] t / 2) —CR * j ffj \ >ar,d

[0521] 12\_U2)

[0522] h(Ul)

[0523] = c0*

[0524]

[0525] V J / 2(t / 2)

[0526] U1and / or U2may be known by measurement. The items of calibration information cRand c0may be determined by performing a method for calibrating a spectrometer device as elsewhere disclosed herein.

[0527] Embodiment 23: The method according to the preceding Embodiment referring to a method for operating a spectrometer device, wherein the items of calibration information cRand c0are determined by performing a method for calibrating a spectrometer device according to the preceding Embodiment.

[0528] Embodiment 24: A spectrometer device for obtaining at least one item of spectral information on at least one object by spectroscopic measurement, wherein the spectrometer device comprises:

[0529] a) at least one sample interface, wherein the sample interface is configured for defining a measurement pose of the at least one object outside of the spectrometer device;

[0530] b) at least one detector, wherein the detector is configured for generating at least one detector signal when detecting light;

[0531] c) at least one first beam path, wherein the first beam path is configured in a manner that first light propagating along the first beam path passes the sample interface of the spectrometer device and interacts with the at least one object, d) at least one second beam path, wherein the second beam path is configured in a manner that second light propagating along the second beam path and does not pass the sample interface of the spectrometer device, wherein an internal calibration target having at least one known optical characteristic is arranged in 240305WO01

[0532] -43 -

[0533] the second beam path in a manner that the second light interacts with the at least one internal calibration target,

[0534] e) at least one first light emitting element, wherein the first light emitting element is configured for emitting first light along the first beam path onto the detector; f) at least one second light emitting element, wherein the second light emitting element is configured for emitting second light along the second beam path onto the detector;

[0535] g) at least one evaluation unit, wherein the evaluation unit is configured for obtaining the item of spectral information by using the method for operating the spectrometer device according to any one of the preceding claims referring to a method for operating a spectrometer device.

[0536] Embodiment 25: The spectrometer device according to the preceding claim referring to a spectrometer device, wherein the at least one detector comprises a plurality of photosensitive elements sensitive to differing wavelength intervals.

[0537] Embodiment 26: The spectrometer device according to any one of the preceding claims referring to a spectrometer device, wherein the spectrometer device further comprises at least one wavelength-selective element, wherein the wavelength-selective element is disposed in at least one of:

[0538] - the at least one first beam path;

[0539] - the at least one second beam path.

[0540] Embodiment 27: The spectrometer device according to the preceding claims referring to a spectrometer device, wherein the at least one the wavelength-selective element is configured and / or arranged in a manner that any photosensitive element of the plurality of photosensitive elements is exposed to an individual spectral range of light.

[0541] Embodiment 28: The spectrometer device according to any one of the preceding claims referring to a spectrometer device, wherein at least one of

[0542] - the first light emitting element;

[0543] - the second light emitting element;

[0544] is at least one of:

[0545] - a thermal radiator;

[0546] - a microelectromechanical system (MEMS)-based emitter;

[0547] - a laser, specifically a vertical cavity surface emitting laser (VCSEL), particularly emitting at least one wavelength in the infrared region; 240305WO01

[0548] - 44 -

[0549] - a light-emitting diode (LED), particularly

[0550] o a LED emitting light that is at least partially located in the infrared spectral range and / or

[0551] o a LED illuminating a phosphor for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range.

[0552] Embodiment 29: A mobile device, wherein the mobile device comprises a spectrometer device according to any one of the preceding claims referring to a spectrometer device.

[0553] Embodiment 30: A computer program comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to any one of the method claims.

[0554] Embodiment 31: The computer program according to the preceding claim, wherein the computer is the spectrometer device according to any one of the preceding Claims referring to the spectrometer device.

[0555] Embodiment 32: A non-transitory computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a computer, cause the computer to perform the method according to any one of the method claims.

[0556] Embodiment 33: The non-transitory computer-readable storage medium according to the preceding claim, wherein the computer is the spectrometer device according to any one of the preceding claims referring to a spectrometer device.

[0557] Short description of the Figures

[0558] Further optional features and embodiments will be disclosed in more detail in the subsequent description of embodiments, preferably in conjunction with the dependent claims. Therein, the respective optional features may be realized in an isolated fashion as well as in any arbitrary feasible combination, as the skilled person will realize. The scope of the invention is not restricted by the preferred embodiments. The embodiments are schematically depicted in the Figures. Therein, identical reference numbers in these Figures refer to identical or functionally comparable elements. 240305WO01

[0559] -45 -

[0560] In the Figures:

[0561] Figure 1 shows an exemplary spectrometer device;

[0562] Figure 2 shows an exemplary method for calibrating a spectrometer device;

[0563] Figure 3 shows an exemplary method for operating a spectrometer device;

[0564] Figure 4 shows an exemplary received dependency

[0565]

[0566] and dependency / 2(^2);

[0567] Figure 5 shows an exemplary function 5;

[0568] Figure 6 shows a further exemplary method for calibrating a spectrometer device: and

[0569] Figure 7 shows a further exemplary method for operating a spectrometer device.

[0570] Detailed description of the embodiments

[0571] In Figure 1, an exemplary spectrometer device 110 for obtaining at least one item of spectral information on at least one object 112 by spectroscopic measurement is shown. The spectrometer device comprises:

[0572] a) at least one sample interface 114, wherein the sample interface 114 is configured for defining a measurement pose of the at least one object 112 outside of the spectrometer device;

[0573] b) at least one detector 116, wherein the detector 116 is configured for generating at least one detector signal when detecting light 118, 120;

[0574] c) at least one first beam path 122, wherein the first beam path 122 is configured in a manner that first light 118 propagating along the first beam path passes the sample interface 114 of the spectrometer device 110 and interacts with the at least one object 112,

[0575] d) at least one second beam path 124, wherein the second beam path 124 is configured in a manner that second light 120 propagating along the second beam path 124 and does not pass the sample interface 112 of the spectrometer device, wherein an internal calibration target 126 having at least one known optical characteristic is arranged in the second beam path 124 in a manner that the second light 126 interacts with the at least one internal calibration target 126, 240305WO01

[0576] -46 -

[0577] e) at least one first light emitting element 128, wherein the first light emitting element 128 is configured for emitting the first light 118 along the first beam path 122 onto the detector 116;

[0578] f) at least one second light emitting element 130, wherein the second light emitting element 130 is configured for emitting second light 120 along the second beam path 124 onto the detector 116.

[0579] Figure 2 shows an exemplary method 144 for calibrating the spectrometer device 110. The method comprises the following steps:

[0580] 1) (denoted by reference number 146) receiving a dependency / i(t i, / -ac) ofaradiation intensity y of a first light emitting element 128 of the spectrometer device 110 depending on a first forward voltage Ul facapplied for driving the first light emitting element 128, specifically wherein the indexfacindicates that the dependency may be determined in a factory calibration, the index facmay be omitted;

[0581] 2) (denoted by reference number 148) receiving a dependency /

[0582]

[0583] 2(I / 2, / ac) °faradiation intensity I2of a second light emitting element 130 of the spectrometer device 110 depending on a second forward voltage U2applied for driving the second light emitting element 130, specifically wherein the indexfacindicates that the dependency may be determined in a factory calibration, the indexfacmay be omitted; 3) (denoted by reference number 150) determining a function b between the dependency / i(t / i) and the dependency I2U2), wherein

[0584] b.= S il- JzC^z)’

[0585] and determining a function

[0586]

[0587] by solving the function b for U2and / or determining a function

[0588]

[0589] by solving the function b for U1in a manner that

[0590] f1(U1) = U2and

[0591] / ■2(u2)= Uy,

[0592] 4) (denoted by reference number 152) determining at least one, two or any one of the following functions by using the function AOA) and / or the function f2(u2y.

[0593] D(U1) =

[0594] R1(U1) / R2(f1(U1))

[0595] W 2)).

[0596] O(O2) =

[0597] R2(U2) ’

[0598] OiW

[0599] £»*([ / i) and

[0600] _ 01 ( / 2 (^2))

[0601]

[0602] O2(O2) ’ 240305WO01

[0603] -47 -

[0604] wherein R^UJ and R1f2(. U2)) are detector signals generated by first light 118 propagating along the first beam path 122 measured while a reference calibration target 140 is arranged at the sample interface 114; wherein R2(f-(U-)) and R2(U2) are detector signals generated by second light 120 propagating along the second beam path 124 measured while the reference calibration target 140 is arranged at the sample interface 114; wherein Oi(t / i) and OI( 2(^2))aredetector signals generated by first light 118 propagating along the first beam path 112 measured while the sample interface is free of an object 112; wherein O2U2) and O2( / i(^i))aredetector signals generated by second light 120 propagating along the second beam path 124 measured while the sample interface 114 is free of an object 112.

[0605] Receiving the dependency (1 / may comprise at least one of:

[0606] - measuring the dependency (14) by performing a measurement; preferably by at least one of:

[0607] o measuring the intensity I1when applying a plurality of different voltages U1

[0608]

[0609] o measuring the intensity I1and the voltage U1when applying the same current at different temperatures.

[0610] Receiving the dependency l2(U2) may comprise at least one of:

[0611] - measuring the dependency l2(U2) by performing a measurement; preferably by at least one of:

[0612] o measuring the intensity I2when applying a plurality of different voltages U2, o measuring the intensity I2and the voltage U2when applying the same current at different temperatures.

[0613] The function b may be determined by dividing the dependency 4(14) and the dependency / 2(t / 2); °rvice versa. The function b may be a constant that is independent of the first forward voltage U1and the second forward voltage U2. At least one of the steps 1), 2) and 3) may be performed independent of and / or before an assembly of the spectrometer device 110. Measuring at least one of the detector signals R^ Ui), R2U2),

[0614]

[0615] and may be performed when the spectrometer device 110 is assembled.

[0616] In Figure 3, an exemplary method 154 for operating a spectrometer device 110 for obtaining at least one item of spectral information on at least one object 112 is shown. 240305WO01

[0617] -48 -

[0618] Step 4) may be performed when the spectrometer device 110 is assembled, wherein the spectrometer device 110 may be configured in a manner that the first beam path 122 is configured for the first light 118 propagating onto a detector 116 of the spectrometer device 110 along the first beam path 122 in a manner that the first light 118 passes at least one sample interface 114 of the spectrometer device 110; wherein the spectrometer device 110 may be configured in a manner that the second beam path 124 is configured for the second light 120 propagating onto a detector 116 of the spectrometer device 110 along the second beam path 124 in a manner that the second light 120 is not passing the at least one sample interface 114 of the spectrometer device 110.

[0619] The method comprises the following steps:

[0620] 1. (denoted by reference number 156) emitting first light 118 along a first beam path 122 onto a detector 116 of the spectrometer device 110 by using at least one first light emitting element 128 of the spectrometer device 110 in order to generate at least one first detector signal

[0621]

[0622] at a known first forward voltage U1applied for driving the first light emitting element 128; wherein the spectrometer device 110 is configured in a manner that the first beam path 122 is configured for first light 118 propagating along the first beam path 122 passing at least one sample interface 114 of the spectrometer device 110; wherein the at least one object 112 is arranged on the at least one sample interface 114 in a manner that first light 118 interacts with the at least one object 112;

[0623] 2. (denoted by reference number 158) emitting second light 120 along a second beam path 124 onto the detector 116 by using at least one second light emitting element 130 of the spectrometer device 110 in order to generate at least one second detector signal S2(I2) at a known second forward voltage U2applied for driving the second light emitting element 130; wherein the spectrometer device 110 is configured in a manner that the second beam path 124 is configured for second light 120 propagating along the second beam path 124 without passing the at least one sample interface 114 of the spectrometer device 110, wherein an internal calibration target 126 having at least one known optical characteristic is arranged in the second beam path 124 in a manner that the second light 120 interacts with the at least one internal calibration target 126;

[0624] 3. (denoted by reference number 160) determining the item of spectral information on the object 112 by evaluating the at least one first detector signal

[0625]

[0626] and the at least one second detector signal S2(I2) by using an evaluation unit 132, wherein evaluating the at least one first detector signal

[0627]

[0628] and the at least one second detector signal S2(I2) comprises using at least one of the following functions 240305WO01

[0629] -49 -

[0630] £>([ ); D(JJ2£>*(t / i) and Z)*([ / 2), wherein the functions

[0631] D(Ui) D(U2y £>*(t / i) and£>*([ / 2) are determined by performing a method for calibrating a spectrometer device 110 according to any one of the preceding claims referring to a method for calibrating a spectrometer device 110..

[0632] The item of spectral information on the object may be determined by using at least one of the equations

[0633] r. - D^UJ - S2m

[0634] fJt. _, sM ))-pt(u2)-s2(u2)

[0635]

[0636] 2) (D([ / 2) - Z)*([ / 2)).s2([ / 2) '

[0637] The spectrometer device further comprises at least one evaluation unit 132, wherein the evaluation unit 132 is configured for obtaining the item of spectral information by using the method for operating the spectrometer device as elsewhere disclosed herein.

[0638] The spectrometer device may further comprise at least one driving unit 138, wherein the driving unit 138 is configured for driving the first light emitting element 128 and / or the second light emitting element 130.

[0639] At least one of

[0640] - the first light emitting element 128;

[0641] - the second light emitting element 130;

[0642] may be at least one of:

[0643] - a thermal radiator;

[0644] - a microelectromechanical system (MEMS)-based emitter;

[0645] - a laser, specifically a vertical cavity surface emitting laser (VCSEL), particularly emitting at least one wavelength in the infrared region;

[0646] - a light-emitting diode (LED), particularly

[0647] o a LED emitting light that is at least partially located in the infrared spectral range and / or

[0648] o a LED illuminating a phosphor for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range. 240305WO01

[0649] - 50 -

[0650] An emittance spectrum of the first light 118 emitted by the first light emitting element 128 may equal an emittance spectrum of the second light 120 emitted by the second light emitting element 130. The second light 120 emitted by the second light emitting element 130 may have a smaller bandwidth than the first light 118 emitted by the first light emitting element 128.

[0651] The first light emitting element 128 may be driven in a polarization multiplexing mode at at least one first polarization. The second light emitting element 130 may be driven in a polarization multiplexing mode at one or more second polarizations, particularly wherein the at least one first polarization is different than the one or more second polarizations.

[0652] The first light emitting element 128 may be driven in a frequency multiplexing mode at at least one first frequency. The second light emitting element 130 may be driven in a frequency multiplexing mode at one or more second frequencies, particularly wherein the at least one first frequency is different than the one or more second frequencies. The one or more second frequencies may comprise a first second frequency that is smaller than the first frequency, and the one or more second frequencies may comprise a second second frequency that is larger than the first frequency.

[0653] The internal calibration target 126 may be at least one of: at least one beam splitter; at least one optical grating.

[0654] A material of the internal calibration target 126 may be or may comprise at least one of:

[0655] - at least one layer of Polytetrafluoroethylene (PTFE),

[0656] - at least one optical coating, such as a white surface coating or at least one color coating, e.g. a near infra-red reflecting color coating,

[0657] - at least one dielectric coating, at least one partially reflective dielectric mirror, - at least one metal coating or metal foil comprising one or more of gold, silver, aluminum and chromium.

[0658] The at least one detector 116 may comprise a plurality of photosensitive elements 134 sensitive to differing wavelength intervals.

[0659] The spectrometer device 110 further may comprise at least one wavelength-selective element 136, wherein the wavelength-selective element 136 is disposed in at least one of:

[0660] - the at least one first beam path 122;

[0661] - the at least one second beam path 120. 240305WO01

[0662] - 51 -

[0663] The at least one the wavelength-selective element 136 may be configured and / or may be arranged in a manner that any photosensitive element 134 of the plurality of photosensitive elements is exposed to an individual spectral range of light 118, 120.

[0664] The exemplary spectrometer 110 device is arranged in a mobile device 142.

[0665] In Figure 4, the received dependency I₁(U₁) (denoted by reference number 162) and the received dependency l2(U2) (denoted by reference number 164) are depicted. On the horizontal axis 166, the forward voltage U is shown. On the vertical axis 168, the radiation intensity I is shown in arbitrary units. The dot denoted by reference number 170 indicates a specific radiation intensity I1for a specific forward voltage U1. The dot denoted by reference number 172 indicates a specific radiation intensity I2for a specific forward voltage U2. The dot denoted by reference number 174 indicates a radiation intensity I2corrected by using the function b (the correction is indiected by the shown arrow).

[0666] Both dependencies may be described by a linear function I = m0+ m1■ U. Since both dependencies / i(t / i) and I2(U2) may be parallel and thereby m1= m2, it holds that

[0667] / i([ / i) _ + _

[0668]

[0669] / 2(t / 2) m2fi+ m2Ur2

[0670] In Figure 5, the function b (denoted by reference number 176) is depicted. On the first horizontal axis 178, the forward voltage U1of the first light emitting element 128 is shown. On the second horizontal axis 180, the forward voltage U2of the second light emitting element 130 is shown. On the vertical axis 182, the function b is shown in arbitrary units.

[0671] In Figure 6, a further exemplary method 184 for calibrating a spectrometer device 110 for obtaining items of calibration information cRand c0is shown. The items of calibration information cRand c0are used in object measurement in order to determine at least one item of spectral information on an object, wherein the spectrometer device 110 comprises:

[0672] - at least one sample interface 114, wherein the sample interface 114 is configured for defining a measurement pose of at least one sample outside of the spectrometer device 110;

[0673] - at least one detector 116, wherein the detector 116 is configured for generating at least one detector signal when detecting light; 240305WO01

[0674] - 52 -

[0675] - at least one first beam path 122, wherein the first beam path 122 is configured in a manner that first light 118 generated by a first light emitting element 128 propagates along the first beam path 122, passes the sample interface 114 of the spectrometer device 110 and interacts with the at least one sample,

[0676] - at least one second beam path 124, wherein the second beam path 124 is configured in a manner that second light 120 generated by a second light emitting element 130 propagates along the second beam path 124 and does not pass the sample interface 114 of the spectrometer device 110, wherein an internal calibration target 126 having at least one known optical characteristic is arranged in the second beam path in a manner that the second light 120 interacts with the at least one internal calibration target 126,

[0677] wherein the method 184 comprises the following steps:

[0678] 1) (denoted by reference number 186) receiving a dependency I₁(U₁) of a radiation intensity I1of the first light emitting element 128 of the spectrometer device 110 depending on a first forward voltage U1applied for driving the first light emitting element 128;

[0679] 2) (denoted by reference number 188) receiving a dependency l2(U2) of a radiation intensity I2of a second light emitting element 130 of the spectrometer device 110 depending on a second forward voltage U2applied for driving the second light emitting element 130;

[0680] 3) (denoted by reference number 190) performing a first measurement of R1, R2for a known first forward voltage U1and a known second forward voltage U2a second measurement of O1, O2for a known first forward voltage U1and a known second forward voltage U2when the spectrometer 110 is assembled, wherein R1is a detector signal generated by first light 118 propagating along the first beam path 122 measured while a reference calibration target 140, being used as the at least one sample, is arranged at the at least one sample interface 114 of the spectrometer device 110, wherein R2is a detector signal generated by second light 120 propagating along the second beam path 124 measured while the reference calibration target 140 is arranged at the at least one sample interface 114; wherein

[0681]

[0682] is a detector signal generated by first light 118 propagating along the first beam path 112 measured while the at least one sample interface 114 is free, wherein O2is a detector signal generated by second light 120 propagating along the second beam path 124 measured while the at least one sample interface 114 is free;

[0683] 4) (denoted by reference number 192) determining the items of calibration information cRand c0by using 240305WO01

[0684] - 53 -

[0685] R_i _ — Cp *; and

[0686] R2

[0687] —co *

[0688]

[0689] 'W

[0690] wherein the determined cRand c0are constants with respects to the first forward voltage U1and the second forward voltage U2.

[0691] At least one of the steps 1), 2) may be performed independent of an assembly of the spectrometer device 110. / ([ / and / (t / 2) may be linear functions and / or may each satisfy 7(0) = 0 such that

[0692] _ W _AA * > U±

[0693]

[0694] ^2(^2) ^2

[0695] and

[0696] cR= cR* A; and

[0697]

[0698] c0=Co *

[0699] In Figure 7, a further exemplary method 194 for operating a spectrometer device 110 for obtaining at least one item of spectral information on at least one object 112 is disclosed. The spectrometer device 110 comprises:

[0700] - at least one sample interface 114, wherein the sample interface 114 is configured for defining a measurement pose of the at least one sample outside of the spectrometer device 110;

[0701] - at least one detector 116, wherein the detector 116 is configured for generating at least one detector signal when detecting light;

[0702] - at least one first beam path 122, wherein the first beam path 122 is configured in a manner that first light 118 generated by a first light emitting element 128 propagates along the first beam path 122, passes the sample interface 114 of the spectrometer device 110 and interacts with the at least one sample,

[0703] - at least one second beam path 124, wherein the second beam path 124 is configured in a manner that second light 120 generated by a second light emitting element 130 propagates along the second beam path 124 and does not pass the sample interface 114 of the spectrometer device 110, wherein an internal calibration target 126 having at least one known optical characteristic is arranged in the second beam path in a manner that the second light 120 interacts with the at least one internal calibration target 126,

[0704] wherein the method 194 comprises the following steps: 240305WO01

[0705] - 54 -

[0706] 1. (denoted by reference number 196) emitting first light 118 along a first beam path 122 onto a detector 116 of the spectrometer device 110 by using at least one first light emitting element 128 of the spectrometer device 110 in order to generate at least one first detector 116 signal at a known first forward voltage U1applied for driving the first light emitting element 128; wherein the at least one object 112, being used as at least one sample, is arranged on the at least one sample interface 114 in a manner that first light 118 interacts with the at least one object 112; 2. (denoted by reference number 198) emitting second light 120 along a second beam path 124 onto the detector 116 by using at least one second light emitting element 130 of the spectrometer device 110 in order to generate at least one second detector 116 signal S2at a known second forward voltage U2applied for driving the second light emitting element 130;

[0707] 3. (denoted by reference number 200) determining the item of spectral information on the object 112 by using a at least one evaluation unit 132 and by using

[0708] ~ ~ S1-D*((71,(72) -S2a(s1, S2,[ / 1,[ / 2) = -log-, - - -v },

[0709]

[0710] wherein

[0711] t / 2) —CR * j ffj \ >ar*d

[0712] = c0*

[0713]

[0714] V J / 2(t / 2)

[0715] The items of calibration information cRand c0may be determined by performing the further exemplary method 184 for calibrating the spectrometer device 110. 240305WO01

[0716] - 55 -

[0717] List of reference numbers

[0718] 110 spectrometer device

[0719] 112 object

[0720] 114 sample interface

[0721] 116 detector

[0722] 118 first light

[0723] 120 second light

[0724] 122 first beam path

[0725] 124 second beam path

[0726] 126 internal calibration target

[0727] 128 first light emitting element

[0728] 130 second light emitting element

[0729] 132 evaluation unit

[0730] 134 photosensitive element

[0731] 136 wavelength-selective element

[0732] 138 driving unit

[0733] 140 reference calibration target

[0734] 142 mobile device

[0735] 144 method for calibrating the spectrometer device

[0736] 146 receiving a dependency / i(t / i)

[0737] 148 receiving a dependency l2(U2)

[0738] 150 determining a function b

[0739] 152 determining at least one function

[0740] 154 method for operating a spectrometer device

[0741] 156 emitting first light along

[0742] 158 emitting second light

[0743] 160 determining an item of spectral information on the object 162 dependency

[0744]

[0745] 164 dependency I2(U2)

[0746] 166 horizontal axis

[0747] 168 vertical axis

[0748] 170 specific radiation intensity I1

[0749] 172 specific radiation intensity I2

[0750] 174 corrected radiation intensity I2

[0751] 176 ratio b

[0752] 178 first horizontal axis 240305WO01

[0753] - 56 -

[0754] 180 second horizontal

[0755] 182 vertical axis

[0756] 184 further exemplary method for calibrating a spectrometer device 186 receiving a dependency / i(t / i)

[0757] 188 receiving a dependency l2(U2)

[0758] 190 performing a first and a second measurement

[0759] 192 determining the items of calibration information cRand c0194 further exemplary method for operating a spectrometer device 196 emitting first light

[0760] 198 emitting second light

[0761] 200 determining the item of spectral information on the object

Claims

240305WO01- 57 -Claims1. A method for calibrating a spectrometer device (110) for obtaining items of calibration information cRand c0, wherein the items of calibration information cRand c0are used in object measurements in order to determine at least one item of spectral information on an object, wherein the spectrometer device (110) comprises:- at least one sample interface (114), wherein the sample interface (114) is configured for defining a measurement pose of at least one sample outside of the spectrometer device (110);- at least one detector (116), wherein the detector (116) is configured for generating at least one detector signal when detecting light;- at least one first beam path (122), wherein the first beam path (122) is configured in a manner that first light (118) generated by a first light emitting element (128) propagates along the first beam path (122), passes the sample interface (114) of the spectrometer device (110) and interacts with the at least one sample,- at least one second beam path (124), wherein the second beam path (124) is configured in a manner that second light (120) generated by a second light emitting element (130) propagates along the second beam path (124) and does not pass the sample interface (114) of the spectrometer device (110), wherein an internal calibration target (126) having at least one known optical characteristic is arranged in the second beam path in a manner that the second light (120) interacts with the at least one internal calibration target (126),wherein the method comprises the following steps:1) receiving a dependency I₁(U₁) of a radiation intensity I1of the first light emitting element (128) of the spectrometer device (110) depending on a first forward voltage U1applied for driving the first light emitting element (128);2) receiving a dependency I2(U2) of a radiation intensity I2of a second light emitting element (130) of the spectrometer device (110) depending on a second forward voltage U2applied for driving the second light emitting element (130);3) performing a first measurement of R1, R2for a known first forward voltage U1and a known second forward voltage U2a second measurement of O1, O2for a known first forward voltage U1and a known second forward voltage U2when the spectrometer (110) is assembled, wherein R±is a detector signal generated by first light (118) propagating along the first beam path (122) measured while a reference calibration target (140), being used as the at least one sample, is arranged at the at least one sample interface (114) of the spectrometer device (110), wherein R2is a detector signal generated by second light (120) propagating along the second240305WO01- 58 -beam path (124) measured while the reference calibration target (140) is arranged at the at least one sample interface (114); wherein 0^ is a detector signal generated by first light (118) propagating along the first beam path (112) measured while the at least one sample interface (114) is free, wherein O2is a detector signal generated by second light (120) propagating along the second beam path (124) measured while the at least one sample interface (114) is free;4) determining the items of calibration information cRand c0by usingRi KUJ— — Cp *; andR2W— c0*'Wwherein the determined cRand c0are constants with respects to the first forward voltage U1and the second forward voltage U2.

2. The method according to the preceding claim, wherein at least one of the steps 1), 2) is performed independent of an assembly of the spectrometer device (110).

3. The method according to any one of the preceding claims, wherein / i(t / i) and / 2C^2)arelinear functions and each satisfy (0) = / 2(°) = ° such that_ W _ / „I * > t / if2(t^2) ^2andcR= cR* A; andc0= c0*.

4. A method for operating a spectrometer device (110) for obtaining at least one item of spectral information on at least one object (112), wherein the spectrometer device (110) comprises:- at least one sample interface (114), wherein the sample interface (114) is configured for defining a measurement pose of at least one sample outside of the spectrometer device (110);- at least one detector (116), wherein the detector (116) is configured for generating at least one detector signal when detecting light;- at least one first beam path (122), wherein the first beam path (122) is configured in a manner that first light (118) generated by a first light emitting element (128)240305WO01- 59 -propagates along the first beam path (122), passes the sample interface (114) of the spectrometer device (110) and interacts with the at least one sample,- at least one second beam path (124), wherein the second beam path (124) is configured in a manner that second light (120) generated by a second light emitting element (130) propagates along the second beam path (124) and does not pass the sample interface (114) of the spectrometer device (110), wherein an internal calibration target (126) having at least one known optical characteristic is arranged in the second beam path in a manner that the second light (120) interacts with the at least one internal calibration target (126),wherein the method comprises the following steps:

1. emitting first light (118) along a first beam path (122) onto a detector (116) of the spectrometer device (110) by using at least one first light emitting element (128) of the spectrometer device (110) in order to generate at least one first detector (116) signal S̃1at a known first forward voltage U1applied for driving the first light emitting element (128); wherein the at least one object (112), being used as at least one sample, is arranged on the at least one sample interface (114) in a manner that first light (118) interacts with the at least one object (112);2. emitting second light (120) along a second beam path (124) onto the detector (116) by using at least one second light emitting element (130) of the spectrometer device (110) in order to generate at least one second detector (116) signal S2at a known second forward voltage U2applied for driving the second light emitting element (130);3. determining the item of spectral information on the object (112) by using a at least one evaluation unit (132) and by using~ ~ S1- D*((71, (72) - S2a(s1, S2, [ / 1, [ / 2) = -log-, - - -v },2 1 2 / {D(n1,n2') -D'(o1,o2)) -s2whereint / 2) —CR * j ffj \ >ar*d= c0*V J / 2(t / 2)240305WO01- 60 -5. The method according to the preceding claim referring to a method for operating a spectrometer device (110), wherein the items of calibration information cRand c0are determined by performing a method for calibrating a spectrometer device (110) according to any one of the preceding claims referring to a method for calibrating a spectrometer device (110).

6. A spectrometer device (110) for obtaining at least one item of spectral information on at least one object (112) by spectroscopic measurement, wherein the spectrometer device (110) comprises:a) at least one sample interface (114), wherein the at least one sample interface (114) is configured for defining a measurement pose of the at least one object (112) being used as at least one sample outside of the spectrometer device (110);b) at least one detector (116), wherein the detector (116) is configured for generating at least one detector (116) signal when detecting light;c) at least one first beam path (122), wherein the first beam path (122) is configured in a manner that first light (118) propagating along the first beam path (122) passes the sample interface (114) of the spectrometer device (110) and interacts with the at least one object (112),d) at least one second beam path (124), wherein the second beam path (124) is configured in a manner that second light (120) propagating along the second beam path (124) does not pass the sample interface (114) of the spectrometer device (110), wherein an internal calibration target (126) having at least one known optical characteristic is arranged in the second beam path (124) in a manner that the second light (120) interacts with the at least one internal calibration target (126),e) at least one first light emitting element (128), wherein the first light emitting element (128) is configured for emitting first light (118) along the first beam path (122) onto the detector (116);f) at least one second light emitting element (130), wherein the second light emitting element (130) is configured for emitting second light (120) along the second beam path (124) onto the detector (116);g) at least one evaluation unit (132), wherein the evaluation unit (132) is configured for obtaining the item of spectral information by using the method for operating the spectrometer device (110) according to any one of the preceding claims referring to a method for operating a spectrometer device (110).240305WO01- 61 -7. A mobile device (142), wherein the mobile device comprises a spectrometer device (110) according to the preceding claim referring to a spectrometer device (110).

8. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to any one of the method claims.

9. The computer program according to the preceding claim, wherein the computer is an evaluation unit (132) of the spectrometer device (110) according to the preceding claim refer- ring to the spectrometer device (110).

10. A non-transitory computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a computer, cause the computer to perform the method according to any one of the method claims.

11. The non-transitory computer-readable storage medium according to the preceding claim, wherein the computer is an evaluation unit (132) of the spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110).

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