EP4673710A1

EP4673710A1 - Synchronous measurement of bias and reference voltage for signal correction of photosensitive element

Info

Publication number: EP4673710A1
Application number: EP24706765.5A
Authority: EP
Inventors: Bernd Scherwath; Celal Mohan OEGUEN; Nico Haser
Original assignee: TrinamiX GmbH
Current assignee: TrinamiX GmbH
Priority date: 2023-02-28
Filing date: 2024-02-27
Publication date: 2026-01-07
Also published as: WO2024180026A1; CN120712463A

Abstract

A method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object (112) by using a spectrometer device (110) is disclosed. The spectrometer device (110) comprises at least one detector (128) comprising at least one photosensitive element (134) configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region, wherein the spectrometer device (110) comprises at least one read-out integrated circuit (135) comprising at least one measurement channel (170), wherein the read-out integrated circuit (135) comprises at least one bias voltage source (172) configured for applying at least one bias voltage V_Bias to the photosensitive element (134), wherein the read-out integrated circuit (135) comprises at least one read-out element (174) configured for determining an output current I_out of the photosensitive element (134), wherein the measurement channel (170) comprises a reference resistor (182) having a known resistance R_Ref, wherein the read-out element (174) is configured for measuring a current I_Ref through the reference resistor (182). The method comprising the following steps: a. applying at least one bias voltage V_Bias to the photosensitive element (134) by using the bias voltage source (172) of the read-out integrated circuit (135), determining the output current I_out of the photosensitive element (134) and measuring the current I_Refthrough the reference resistor (182) having the known resistance R_Ref; b. evaluating, by using at least one evaluation unit (136), the output current I_out of the photosensitive element (134) and the current I_Refthrough the reference resistor (182) thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object (112) is compensated for the bias voltage influence.

Description

Synchronous Measurement of Bias and Reference Voltage for Signal Correction of Photosensitive element

Technical Field

The present invention refers to a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object and a spectrometer device for obtaining spectroscopic information on at least one object. The invention further refers to a computer program and a computer-readable storage medium for performing the method. Such devices and methods can, in general, be used for investigating or monitoring purposes, in particular, in the infrared (IR) spectral region, especially in the near-infrared (NIR) spectral region, and in the visible (VIS) spectral region, e.g. in a spectral region allowing to mimic a human's ability of color sight. However, further applications are feasible.

Background art

Spectrometer devices are known to be efficient tools for obtaining information on the spectral properties of an object, when emitting, irradiating, reflecting and/or absorbing light. Spectrometer devices, thus, may assist in analyzing samples or other tasks in which information on the spectral properties of an object is of interest.

Usually, in spectrometer devices, spectral information is obtained via one or more detectors and one or more wavelength-selective optical elements, such as one or more dispersive optical elements, filters such as bandpass filters, prisms, gratings, interferometers, or the like. The detectors may comprise any type of light-sensitive element, such as one or more single or multiple pixel detectors, line detectors or array detectors having one- or two-dimensional arrays of pixels. Further, spectrometer devices may comprise one or more light sources. Thus, in spectroscopy, typically, tunable light sources, e.g. lasers, and/or broad-band emitting light sources are used, such as halogen-gas filled light bulbs and/or hot filaments. However, additionally or alternatively, other light sources, such as light-emitting diodes have also been proposed for the visible spectral region.

As an example, US 2010/208261 A1 describes a device for determining at least one optical property of a sample. The device comprises a tunable excitation light source for applying excitation light to the sample. The device furthermore comprises a detector for detecting detection light emerging from the sample. The excitation light source comprises a light-emitting diode array, which is configured at least partly as a monolithic light-emitting diode array. The monolithic light-emitting diode array comprises at least three light-emitting diodes each having a different emission spectrum.

US 8,164,050 B2 describes a multi-channel source assembly for downhole spectroscopy that has individual sources that generate optical signals across a spectral range of wavelengths. A combining assembly optically combines the generated signals into a combined signal and a routing assembly that splits the combined signal into a reference channel and a measurement channel. Control circuitry electrically coupled to the sources modulates each of the sources at unique or independent frequencies during operation.

Further, US 7,061 ,618 B2 describes integrated spectroscopy systems, wherein in some examples, integrated tunable detectors, using one or multiple Fabry-Perot tunable filters, are provided. Other examples use integrated tunable sources combining one or multiple diodes, such as superluminescent light-emitting diodes (SLED), and a Fabry Perot tunable filter or etalon.

Furthermore, US 5,475,221 A describes an optical device which uses an array of light-emitting diodes, controlled by multiplexing schemes, to replace conventional broad band light sources in devices such as spectrometers.

Generally, spectrometer devices are subject to various internal and external influences, such as environmental influences, which may have an impact on the results of the spectroscopic measurements. In order to correct and/or compensate for these influences, various calibration and/or correction methods are known. These calibration methods may be performed once or several times, such as under laboratory conditions, e.g. by the manufacturer. However, also a plurality of on-line calibration techniques are known which may be performed by performing one or more correction and/or calibration steps in between two spectroscopic measurements or even during the measurements.

US 09360366 B1 discloses a self-referencing spectrometer that simultaneously auto-calibrate and measure optical spectra of physical object utilizing shared aperture as optical inputs. The concurrent measure and self-calibrate capabilities makes it possible as an attachment spectrometer on a mobile computing device without requiring an off-line calibration with an external reference light source. Through the mobile computing device, the obtained spectral information and imagery captured can be distributed through the wireless communication networks.

DE 102014013848 B4 discloses a microspectrometer, in particular a NIR microspectrometer for mobile applications in battery-operated terminals, to overcome the nonminiaturization and handheld limitations of the aforementioned system configurations, a microspectrometer system, and a calibration method. The miniaturized NIR spectrometer is to be designed without active temperature stabilization. Instead, according to the invention, the spectral sensitivity function is recorded on several levels in the expected working temperature range as part of a factory temperature calibration step (QEA = f(T); measured with an integrated temperature sensor).

WO 2019/191698 A2 relates to a self-referenced spectrometer for providing simultaneous measurement of a background or reference spectral density and a sample or other spectral density. The self-referenced spectrometer includes an interferometer optically coupled to receive an input beam and to direct the input beam along a first optical path to produce a first interfering beam and a second optical path to produce a second interfering beam, where each in- terfering beam is produced prior to an output of the interferometer. The spectrometer further includes a detector optically coupled to simultaneously detect a first interference signal produced from the first interfering beam and a second interference signal produced from the second interfering beam, and a processor configured to process the first interference signal and the second interference signal and to utilize the second interference signal as a reference signal in processing the first interference signal.

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

US 06667802 B2 discloses a method of calibrating a spectrographic inspection system. The method comprises providing a plurality of packages, each of the plurality of packages containing a group of items, wherein each of the groups of items has a known composition, measuring the reflectance value of each of the groups of items and thereby obtaining a reference reflectance value set, normalizing the reference reflectance value set and thereby creating a normalized reference reflectance value set, and storing the normalized reference reflectance value set.

US 06717669 B2 discloses auto-calibrating spectrometers and methods that measure transmission or reflection versus wavelength of a sample without need for calibration for long periods of time. Reflection and transmission spectrometers along with auto-calibrating methods for use therewith are disclosed. Light is focused onto a sample using a lens or similar optical element that transmits light towards the sample reflects light impinging upon it, and transmits light reflected from the sample. If one monitors the light reflected from the first lens and sample, very useful information is available related to the system response versus time. The reflected light is monitored from the first lens and sample, and the system changes over time are corrected for using this reflected light.

US 09448114 B2 discloses a spectrometer which comprises a plurality of isolated optical channels comprising a plurality of isolated optical paths. The isolated optical paths decrease crosstalk among the optical paths and allow the spectrometer to have a decreased length with increased resolution. In many embodiments, the isolated optical paths comprise isolated parallel optical paths that allow the length of the device to be decreased substantially. In many embodiments, each isolated optical path extends from a filter of a filter array, through a lens of a lens array, through a channel of a support array, to a region of a sensor array. Each region of the sensor array comprises a plurality of sensor elements in which a location of the sensor element corresponds to the wavelength of light received based on an angle of light received at the location, the focal length of the lens and the central wavelength of the filter.

WO 2019/204515 A1 discloses methods of sensor readout and calibration and circuits for performing the methods. In some embodiments, the methods include driving an active sensor at a voltage. In some embodiments, the methods include use of a calibration sensor, and the circuits include the calibration sensor. In some embodiments, the methods include use of a calibration current source and circuits include the calibration current source. In some embodiments, a sensor circuit includes a Sigma-Delta ADC. In some embodiments, a column of sensors is readout using first and second readout circuits during a same row time.

EP 2 690 416 A1 discloses an infrared image sensor for detecting infrared rays. The infrared image sensor includes a light-receiving unit including a pixel region in which a plurality of pixels are arranged and at least one reference pixel; a difference circuit for acquiring a first differential signal that is a differential signal between a signal of one pixel contained in the pixel region and a signal of the reference pixel and a second differential signal that is a differential signal between signals of two predetermined pixels out of the pixels contained in the pixel region; and a pixel signal calculating unit that calculates a signal of each of the pixels on the basis of the first differential signal and the second differential signal.

Despite the advantages achieved by known methods and devices, several technical challenges remain in the field of spectroscopy and spectroscopic devices, specifically for spectroscopy in the near-infrared range. Specifically, optoelectronic components, such as light sources, detectors, read-out electronics or the like, generally comprise strong temperature dependencies. If the temperature dependency is not corrected, a drift due to the temperature change may lead to a decrease in the measurement reproducibility of a spectrometer device.

Generally, these technical challenges can be avoided either by temperature-stabilizing the temperature-sensitive optoelectronic components using further hardware, e.g. thermoelectric coolers, or by monitoring and correcting the temperature change of the temperature-sensitive optoelectronic component, e.g. by a direct monitoring or by a monitoring of the consequent change of the electrical and/or optical property of the respective component.

However, in the latter case, the monitored properties can be of different natures, e.g. voltage, current, resistance, power consumption, optical efficiency, spectral shift or the like. The monitoring of each of these properties may require different electrical circuits with different electrical components. Furthermore, the change of these properties due to the temperature change may be very small compared to their initial value. Thus, the resolution of the monitoring system generally has to be high. In summary, these constraints may cause complex and expensive systems with large footprint. Such complex system are generally not feasible for size and cost sensitive applications.

Problem to be solved It is therefore desirable to provide devices and methods which at least partially address the above-mentioned technical challenges. In particular, it is an object of the invention to provide a spectrometer device and a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object which minimize the hardware effort for correcting for external and/or internal influences, such as temperature, in spectrometer device.

Summary

This problem is addressed by a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object, a computer program and a computer-read- able storage medium, and a spectrometer device for obtaining spectroscopic information on at least one object, 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.

In a first aspect of the present invention, a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object by using a spectrometer device is disclosed.

The term “bias voltage influence” 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 any influence relating to the bias voltage on the detector signal. For example, the bias voltage influence may be one or more of noise, ripple voltage, and at least one drift, e.g. a temperature drift.

The term “compensating for a bias voltage influence” 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 one or more of considering the bias voltage influence when obtaining the spectroscopic information and/or correcting the spectroscopic information for the bias voltage information and/or removing the influence relating to the bias voltage from the spectroscopic information on the object. The compensating may comprise using at least one mathematical algorithm, e.g. applying at least one correction function.

The term “noise” 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 disturbance in a signal. In the following the term noise will be used representative for any of the above listed bias voltage influence.

The spectrometer device comprises at least one detector comprising at least one photosensitive element configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region. The spectrometer device comprises at least one read-out integrated circuit comprising at least one measurement channel. The read-out integrated circuit comprises at least one bias voltage source configured for applying at least one bias voltage V_Bias to the photosensitive element. The read-out integrated circuit comprises at least one read-out element configured for determining an output current I_out of the photosensitive element. The measurement channel comprises a reference resistor having a known resistance R_Ref. The read-out element is configured for measuring a current l_Ref through the reference resistor.

The method comprises the following steps that may be performed in the given order. However, a different order may also be possible. In particular, one, more than one or even all of the method steps may be performed once or repeatedly. Further, the method steps may be performed successively or, alternatively, one or more of the method steps may be performed in a timely overlapping fashion or even in a parallel fashion and/or in a combined fashion. The method may further comprise additional method steps that are not listed.

The method comprising the following steps: a. applying at least one bias voltage V_Bias to the photosensitive element by using the bias voltage source, determining the output current I_out of the photosensitive element and measuring the current I_Ref through the reference resistor having the known resistance RRef< b. evaluating, by using the evaluation unit, the output current I_out of the photosensitive element and the current l_Ref through the reference resistor thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object is compensated for the bias voltage influence.

The method may further comprise evaluating the output current I_out of the photosensitive element and deriving the spectroscopic information on the object therefrom by using the evaluation unit. The method further may comprise compensating the output current l_out of the photosensitive element and/or the spectroscopic information on the object for the bias voltage influence. The compensating may be performed in post processing, e.g. by one or more of kick out noisy parts, correct the noisy samples, remove the drift, and the like.

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. 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.

The spectrometer device, as an example, may be or may comprise a device which allows for a measurement of at least one spectrum, e.g. for the measurement of a spectral flux, specifically as a function of a wavelength or detection wavelength. The spectrum may be acquired, as an example, in absolute units or in relative units, e.g. in relation to at least one reference measurement. Thus, as an example, the acquisition of the at least one spectrum specifically may be performed either for a measurement of the spectral flux (unit W/nm) or for a measurement of a spectrum relative to at least one reference material (unit 1), which may describe the property of a material, e.g., reflectance over wavelength. Additionally or alternatively, the reference measurement may be based on a reference light source, an optical reference path, a calculated reference signal, e.g. a calculated reference signal from literature, and/or on a reference device.

Specifically, the at least one spectrometer device may be a diffusive reflective spectrometer device configured for acquiring spectral information from the light which is diffusively reflected by the at least one object, e.g. the at least one sample. Additionally or alternatively, the at least one spectrometer device may be or may comprise an absorption- and/or transmission spectrometer. In particular, measuring a spectrum with the spectrometer device may comprise measuring absorption in a transmission configuration. Specifically, the spectrometer device may be configured for measuring absorption in a transmission configuration. As outlined above, however, other types of spectrometer devices are also feasible.

The spectrometer device, as will be outlined in further detail below, may comprise at least one light source, in particular at least one artificial light source. The light source, as an example, may be at least one of a tunable light source, a light source having at least one fixed emission wavelength and a broadband light source. The spectrometer device, as will be outlined in further detail below, further comprises at least one detector configured for detecting light, such as light which is at least one of transmitted, reflected or emitted from the at least one object. The spectrometer device further may comprise, as will be outlined in further detail below, at least one wavelength-selective element, such as at least one of a grating, a prism and a filter, e.g. a length variable filter having varying transmission properties over its lateral extension. The wavelength-selective element may be used for separating incident light into a spectrum of constituent wavelength signals whose respective intensities are determined by employing a detector such as a detector having a detector array as described below in more detail. Other embodiments of light source may be possible, too. For example, ambient light may be used.

The spectrometer device, specifically, may be a portable spectrometer device. 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 m³ or 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 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.

The term “spectroscopic information”, also referred to as “spectral information” or as “an 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 at least one object and/or radiation emitted by 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.

The spectrometer device specifically may be configured for acquiring at least one spectrum or at least a part of a spectrum of detection light propagating from the object to the spectrometer. The spectrum may describe the radiometric unit of spectral flux, e.g. given in units of watt per nanometer (W/nm), or other units, e.g. as a function of the wavelength of the detection light. Thus, the spectrum may describe the optical power of light, e.g. in the NIR spectral range, in a specific wavelength band. The spectrum may contain one or more optical variables as a function of the wavelength, e.g. the power spectral density, electric signals derived by optical measurements and the like. The spectrum may indicate, as an example, the power spectral density and/or the spectral flux of the object, e.g. of a sample, e.g. relative to a reference sample, such as a transmittance and/or a reflectance of the object, specifically of the sample. The spectrum, as an example, may comprise at least one measurable optical variable or property of the detection light and/or of the object, specifically as a function of the illumination light and/or the detection light. As an example, the at least one measurable optical variable or property may comprise at least one at least one radiometric quantity, such as at least one of a spectral density, a power spectral density, a spectral flux, a radiant flux, a radiant intensity, a spectral radiant intensity, an irradiance, a spectral irradiance. Specifically, as an example, the spectrometer device, specifically the detector, may measure the irradiance in Watt per square meter (W/m²), more specifically the spectral irradiance in Watt per square meter per nanometer (W/m²/nm). Based on the measured quantity the spectral flux in Watt per nanometer (W/nm) and/or the radiant flux in Watt (W) may be determined, e.g. calculated, by taking into account an area of the detector.

The term “object” 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 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. The object specifically may comprise at least one sample which may fully or partially be analyzed by spectroscopic methods. As an example, the object may be or may comprise at least one of: human or animal skin; edibles, such as fruits; plastics and textile.

The spectrometer device may comprise at least one light source for generating illumination light for illuminating the object. However, the method according to the present invention may be used without illumination, e.g. in a dark measurement.

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 the typical purposes of the present invention is light in the infrared (IR) spectral range, more preferred, in the near infra- red (NIR) and/or the mid infrared spectral range (M id I R), 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.

Consequently, the term “light 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 in the sense of the above-mentioned definition. The light source specifically may be or may comprise at least one electrical light source, such as an electrically driven light source.

The term “illuminate”, 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 exposing at least one element to light.

In spectroscopy, various sources and paths of light are to be distinguished. In the context of the present invention, a nomenclature is used which, firstly, denotes light propagating from the light source to the object as “illuminating light” or “illumination light”. Secondly, light propagating from the object to the detector is denoted as “detection light”. The detection light may comprise at least one of illumination light reflected by the object, illumination light scattered by the object, illumination light transmitted by the object, luminescence light generated by the object, e.g. phosphorescence or fluorescence light generated by the object after optical, electrical or acoustic excitation of the object by the illumination light or the like. Thus, the detection light may directly or indirectly be generated through the illumination of the object by the illumination light.

Further, as will be outlined in detail below, within the light source itself, a distinction may be made between various light sources, such as primary light sources and secondary light sources. Thus, as will be outlined in further detail below, “primary light”, also referred to as “pump light”, may be generated by a primary light source such as at least one light-emitting diode and may subsequently be transformed into “secondary light”, such as by using light conversion, e.g. through one or more phosphor materials. The illumination light may be or may comprise at least one of the primary light or a part thereof, the secondary light or a part thereof, or a mixture of both.

The light source generally can be embodied in various ways. For example, the light source can be part of the spectrometer device, such as in a housing of the spectrometer device. Alternatively or additionally, however, the at least one light source can also be arranged outside a housing, for example as a separate light source. The light source can be arranged separately from the object and illuminate the object from a distance. The light source may specifically be configured for emitting light in a spectral range at least partially comprising the infrared spectral range, specifically the near-infrared spectral range, more specifically in a spectral range from 760 nm to 3 pm, more specifically in a spectral range from 1 pm to 3 pm, more specifically in a spectral range from 1 pm to 2.5 pm, more specifically in a spectral range from 1 .3 pm to 2.5 pm, most specifically in a spectral range from 1.5 pm to 2.2 pm.

The light source may comprise at least one light source selected from the group consisting of: an incandescent lamp; a light-emitting diode (LED); a laser, specifically a laser diode, a solid- state laser, a gas laser, a quantum cascade laser; a plasma light source; a low pressure discharge lamp, specifically a low pressure fluorescent lamp; a high pressure discharge lamp; an electrical light source. The low pressure discharge lamp may refer to any gas discharge lamp being operated at a gas pressure below 1 % of atmospheric pressure under normal conditions. The high pressure discharge lamp may refer to any gas discharge lamp being operated at a gas pressure above 10% of atmospheric pressure under normal conditions. The electrical light source may refer to any type of light source which can be driven by means of electrical current and voltage.

The light source may specifically comprise at least one light-emitting diode and at least one luminescent material for light-conversion of primary light generated by the light-emitting diode. Specifically, the illumination light may be at least one of a combination of the primary light and light generated by the light-conversion by the luminescent material and light generated by the light conversion of the luminescent material, also referred to as secondary light.

The term “light-emitting diode” or briefly “LED”, 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 optoelectronic semiconductor device capable of emitting light when an electrical current flows through the device. The optoelectronic semiconductor device may be configured for generating the light due to various physical processes, including one or more of spontaneous emission, induced emission, decay of metastable excited states and the like. Thus, as an example, the light-emitting diode, may comprise one or more of: a light-emitting diode based on spontaneous emission of light, in particular an organic light-emitting diode, a light-emitting diode based on superluminescence (sLED), or a laser diode (LD). In the following, without narrowing the possible embodiments of the light-emitting diode to any of the before-mentioned physical principles or setups, the abbreviation “LED” will be used for any type of light-emitting diode. Specifically, the LED may comprise at least two layers of semiconductor material, wherein light may be generated at at least one interface between the at least two layers of semiconductor material, specifically due to a recombination of positive and negative electrical charges, e.g. due to electron-hole recombination. The at least two layers of semiconductor material may have differing electrical properties, such as at least one of the layers being an n-doped semiconductor material and at least one of the layers being a p-doped semiconductor material. Thus, as an example, the LED may comprise at least one pn-junction and/or at least one pin-set up. It shall be noted, however, that other device structures are feasible, too. The at least one semiconductor material may specifically be or may comprise at least one inorganic semiconducting material. It shall be noted, however, that organic semiconducting materials may be used additionally or alternatively.

Generally, the LED may convert electrical current into light, specifically into the primary light, more specifically into blue primary light, as will be outlined in further detail below. The LED, thus, specifically may be a blue LED. The LED may be configured for generating the primary light, also referred to as the “pump light”. Thus, the LED may also be referred to as the “pump LED”. The LED specifically may comprise at least one LED chip and/or at least one LED die. Thus, the semiconductor element of the LED may comprise an LED bare chip.

Various types of LEDs suitable for generating the primary light are known to the skilled person and may also be applied in the present invention. Specifically, p-n-diodes may be used. As an example, one or more LEDs selected from the group of an LED on the basis of indium gallium nitride (InGaN), an LED on the basis of GaN, an LED on the basis of InGaN/GaN alloys or combinations thereof and/or other LEDs may be used. Additionally or alternatively, quantum well LEDs may also be used, such as one or more quantum well LEDs on the basis of InGaN. Additionally or alternatively, superluminescence LEDs (sLED) and/or quantum cascade lasers may be used.

The term “luminescence” 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 spontaneous emission of light by a substance not resulting from heat. Specifically, luminescence may refer to a cold-body radiation. More specifically, the luminescence may be initiated or excited by irradiation of light, in which case the luminescence is also referred to as “photoluminescence”. The property of a material being capable of performing luminescence, in the context of the present invention, is referred to by the adjective “luminescent”. The at least one luminescent material specifically may be a photoluminescent material, i.e. a material which is capable of emitting light after absorption of photons or excitation light. Specifically, the luminescent material may have a positive Stokes shift, which generally may refer to the fact that the secondary light is red-shifted with respect to the primary light.

The at least one luminescent material, thus, may form at least one converter, also referred to as a light converter, transforming primary light into secondary light having different spectral properties as compared to the primary light. Specifically, a spectral width of the secondary light may be larger than a spectral width of the primary light, and/or a center of emission of the secondary light may be shifted, specifically red-shifted, compared to the primary light. Specifically, the at least one luminescent material may have an absorption in the ultraviolet and/or blue spectral range and an emission in the near-infrared and/or infrared spectral range. Thus, generally, the luminescent material or converter may form at least one component of the phosphor LED converging primary light or pump light, specifically in the blue spectral range, into light having a longer wavelength, e.g. in the near-infrared or infrared spectral range.

Various types of conversion and/or luminescence are known and may be used in the context of the present invention. Thus, specifically, the conversion can occur via a dipole-allowed transition in the luminescent material, also referred to as fluorescence, and/or via a dipole-forbidden, thus long-lived, transition in the luminescent material, often also referred to as phosphorescence.

The luminescent material, specifically, may, thus, form at least one converter or light converter. The luminescent material may form at least one of a converter platelet, a luminescent and specifically a fluorescent coating on the LED and phosphor coating on the LED. The luminescent material may, as an example, comprise one or more of the following materials: Cerium-doped YAG (YAG:Ce3+, or Y3AI5O12:Ce3+); rare-earth-doped Sialons; copper- and aluminium-doped zinc sulfide (ZnS:Cu,AI).

The LED and the luminescent material, together, may form a so-called “phosphor LED”. Consequently, the term “phosphor light-emitting diode” or briefly “phosphor LED”, 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 combination of at least one light-emitting diode configured for generating primary light or pump light, and at least one luminescent material, also referred to as a “phosphor”, configured for light-conversion of the primary light generated by the light-emitting diode. The phosphor LED may form a packaged LED light source, including the LED die, e.g. a blue LED emitting blue pump light, as well as the phosphor, which, as an example, fully or partially coats the LED, which is, as an example, configured for converting the primary light or blue light into light having differing spectral properties, specifically into near-infrared light. Generally, the phosphor LED may be packaged in one housing or may be unpackaged. Thus, the LED and the at least one luminescent material for light-conversion of the primary light generated by the light-emitting diode may specifically be housed in a common housing. Alternatively, however, the LED may also be an unhoused or bare LED which may fully or partially be covered with the luminescent material, such as by disposing one or more layers of the luminescent material on the LED die. The phosphor LED, generally, may form an emitter or light source by itself.

In the light source, specifically the phosphor LED, the at least one luminescent material specifically may be located with respect to the light-emitting diode such that a heat transfer from the light-emitting diode to the luminescent material is possible. More specifically, the luminescent material may be located such that a heat transfer by one or both of thermal radiation and heat conduction is possible, more preferably by heat conduction. Thus, as an example, the luminescent material may be in thermal contact and/or in physical contact with the light-emitting diode. As an example, the luminescent material may form one or more coatings or layers in contact with or in close proximity to the light-emitting diode, such as with one or more of the semiconductor materials of the light-emitting diode. Thereby, generally, a temperature of the luminescent material and a temperature of the light-emitting diode may be coupled.

The at least one luminescent material specifically may form at least one layer. Generally, various alternatives of positioning the luminescent material with respect to the light-emitting diode are feasible, alone or in combination. Firstly, the luminescent material, e.g., at least one layer of the luminescent material, such as the phosphor, may be positioned directly on the light-emitting diode, which is also referred to as a “direct attach”, e.g. with no material in between the LED and the luminescent material or with one or more transparent materials in between, such as with one or more transparent materials, specifically transparent for the primary light, in between the LED and the luminescent material. Thus, as an example, a coating of the luminescent material may be placed directly or indirectly on the LED. Additionally or alternatively, the luminescent material, as an example, may form at least one converter body, such as at least one converter disk, which may be placed on top of the LED, e.g. by adhesive attachment of the converter body to the LED. Additionally or alternatively, the luminescent material may also be placed in a remote fashion, such that the primary light from the LED has to pass an intermediate optical path before reaching the luminescent material. This placement may also be referred to as a “remote placement” or as a “remote phosphor”. Again, as an example, the luminescent material in the remote placement may form a solid body or converter body, such as a disk or converter disk. Further, in case of the remote placement, the luminescent material may also be a coating. In particular, an object which is transmitting light, e.g. a thin glass substrate, module window, comprising and/or being made of glass or plastics, may be coated with the phosphor. Alternatively, a reflective surface may be coated with the phosphor. This could be a flat or rough mirror, which may comprise and/or be made of a high-reflective index material substrate, e.g. silicon, or a gold, silver, aluminum or chromium coated flat or rough surface, e.g. glass, or a plastic. In the intermediate optical path, one or more optical elements may be placed, such as one or more of a lens, a prism, a grating, a mirror, an aperture or a combination thereof. Thus, specifically, an optical system having imaging properties may be placed in between the LED and the luminescent material, in the intermediate optical path. Thereby, as an example, the primary light may be focused, or bundled onto the converter body.

The spectrometer device may further comprises at least one driving unit for electrically driving the light source. 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 one or both of at least one control parameter and/or electrical power to another device. 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 at least one light source. The driving unit specifically may be configured for controlling one or more electrical parameters of an electrical power provided to the light source, specifically to the at least one light-emitting diode. As an example, the driving unit may be configured for providing an electrical current to the LED, specifically for controlling an electrical current through the LED. Therein, as an example, the driving unit may be configured for adapting a voltage provided to the LED, the voltage being required for achieving a specific electrical current through the LED. The driving unit may comprise one or more of a current source and a voltage source. Specifically, the driving unit may comprise at least one current source for providing at least one predetermined current to the LED, wherein the current source specifically may be configured for adjusting or controlling a voltage applied to the LED in order to generate the predetermined current. The driving unit, as an example, may comprise one or more electrical components, such as integrated circuits, for driving the light source. The driving unit may fully or partially be integrated into the light source or may be separated from the light source.

The spectrometer device comprises at least one detector comprising at least one photosensitive element configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region. Generally, the parameter to be determined using the spectroscopy is the irradiation of the detector at the given wavelength. In particular, the detector signal is the current (also denoted as current signal), denoted as I_out, wherein the current l_out depends on the irradiation. A change of current while irradiation may be due to resistance change by the photosensitive element and due to the generated photocurrent by the photosensitive element.

The detector, in particular, is configured for detecting detection light from the object and generating at least one detector signal. 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 “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 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 specifically comprise at least one detector current indicating an accumulated photocurrent from the detector, specifically at least one detector current from each pixel of the detector. The detector signal may directly or indirectly be provided by the detector to the evaluation unit, such that the detector and the evaluation unit may be directly or indirectly connected. The detector signal may be used as a “raw” detector signal and/or may be processed or preprocessed before further used, e.g. by filtering and the like. Thus, the 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.

In the present case, the detector is configured for detecting light propagating from the object to the spectrometer device or more specifically to the detector of the spectrometer device, which, according to the above-mentioned nomenclature, is referred to as “detection light”. Thus, specifically, the detector may be or may comprise at least one optical detector. The optical 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 optical 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 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 sensitive area of the detector is illuminated.

The detector may comprise one single optically sensitive element or area or a plurality of optically sensitive elements or areas, also referred to as “photosensitive elements”. Specifically, the detector may be or may comprise at least one detector array, more specifically an array of photosensitive elements, as will be outlined in further detail below. Each of the photosensitive elements may comprise at least a photosensitive area which may be adapted for generating an electrical signal depending on the intensity of the incident light, wherein the electrical signal may, in particular, be provided to the evaluation unit, as will be outlined in further detail below.

The photosensitive area as comprised by each of the optically sensitive elements may, especially, be a single, uniform photosensitive area which is configured for receiving the incident light which impinges on the individual optically sensitive elements. However, other arrangements of the optically sensitive elements may also be conceivable.

The light-sensitive region may comprises at least one photoconductive material selected from the group consisting of lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); Silicon Germanium (SiGe); extrinsic semiconductors, organic semiconductors.

The photosensitive element, in particular the array of optically sensitive elements, may be designed to generate detector signals, preferably electronic signals, associated with the intensity of the incident light which impinges on the individual optically sensitive elements. The detector signal may be an analogue and/or a digital signal. The electronic signals for adjacent pixelated sensors can, accordingly, be generated simultaneously or else in a temporally successive manner. By way of example, during a row scan or line scan, it is possible to generate a sequence of electronic signals which correspond to the series of the individual optically sensitive elements which are arranged in a line. In addition, the individual optically sensitive elements may, preferably, be active pixel sensors which may be adapted to amplify the electronic signals prior to providing it to the evaluation unit. For this purpose, the detector may comprise one or more signal processing devices, such as one or more filters and/or analogue-digital-converters for processing and/or preprocessing the electronic signals.

In case the detector comprises an array of optically sensitive elements, the detector, as an example, may be selected from any known pixel sensor, in particular, from a pixelated organic camera element, preferably, a pixelated organic camera chip, or from a pixelated inorganic camera element, preferably, a pixelated inorganic camera chip, more preferably from a CCD chip or a CMOS chip, which are, commonly, used in various cameras nowadays. As an alternative, the detector generally may be or comprise a photoconductor, in particular an inorganic photoconductor, especially PbS, PbSe, Ge, InGaAs, ext. InGaAs, InSb, or HgCdTe. As a further alternative, it may comprise at least one of pyroelectric, bolometer or thermophile detector elements. Thus, a camera chip having a matrix of 1 x N pixels or of M x N pixels may be used here, wherein, as an example, M may be < 10 and N may be in the range from 1 to 50, preferably from 2 to 20, more preferred from 5 to 10. Further, a monochrome camera element, preferably a monochrome camera chip, may be used, wherein the monochrome camera element may be differently selected for each optically sensitive element, especially, in accordance with the varying wavelength along the series of the optical sensors.

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

The spectrometer device comprises at least one read-out integrated circuit comprising at least one measurement channel.

The term “measurement channel” 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 electrical circuit or a set of electrical circuits configured for measuring an output current I_out of the photosensitive element. Specifically, the measurement channel may comprise at least one electrical circuit configured for measuring an output current l_out of the photosensitive element and at least one electrical circuit configured for measuring a current I_Ref through the reference resistor, specifically at least partially simultaneously. For example, the measurement channel may comprise at least one measurement channel for the photosensitive element and at least one measurement channel of for the reference resistor, wherein, in particular, the measurement channel for the photosensitive element and the measurement channel for the reference resistor may at least partially overlap with each other, such as by sharing common electrical circuits or any part thereof. As outlined above, the detector may comprise the plurality of photosensitive elements. In this case of the detector comprising a plurality of the photosensitive elements, the read-out integrated circuit may be a multi-channel read-out integrated circuit comprising a plurality of measurement channels. Each of the measurement channels may be configured for measuring the output current I_0llt of the associated photosensitive element. The multi-channel read-out integrated circuit may comprise at least one measurement channel associated with each photosensitive element and being specifically configured for read-out of the detector signal of the associated photosensitive element.

The term “read-out”, also referred to as “reading”, 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 action or process of quantifying and/or processing at least one physical property and/or a change in at least one physical property detected by at least one device, specifically by at least one component of the spectrometer device. The term “integrated circuit” (IC) 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 set of electronic circuits on a chip. The chip may comprise at least one substrate made of a semiconductor material, specifically on at least one substrate made of silicon. The term “read-out integrated circuit” (ROIC) 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 integrated circuit configured for reading the at least one component of the spectrometer device. For example, the ROIC is configured for reading the detector, wherein the reading may comprise accumulating a photocurrent from each pixel of the detector for generating a detector signal and transferring the detector signal to at least one output for further evaluation.

The read-out integrated circuit may specifically be an analog integrated circuit, i.e. an integrated circuit comprising a set of electrical circuits with active elements, such as transistors, and/or passive elements, such as capacitors, resistors and/or inductors, being configured for processing continuous signals, specifically continuous analog signals.

The read-out integrated circuit comprises at least one bias voltage source configured for applying at least one bias voltage V_Blas to the photosensitive element. The term “bias voltage 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 at last one voltage source configured for generating a bias voltage. The bias voltage source may be configured for applying at least one, e.g. constant, bias voltage V_Blas to the photosensitive element, specifically to the light-sensitive region which may be regarded as a resistance in this context. The photosensitive element may be or may comprise at least one passive detectors, e.g. as outlined above, PbS may be used. PbS is among other things sensitive to light and changes its resistance based on the illuminance. This effect can be used to build light sensitive sensors out of PbS material. Such a PbS measurement cell may be a passive detector. Therefore, the bias voltage V_Blas is applied to the photosensitive element.

In particular, an output signal of the photosensitive element is the output current I_out which is dependent of light E_v, the bias voltage V_Bias, the resistance R of the photosensitive element, and the temperature T. The output current I_out may be proportional to the bias voltage V_Blas and inversely proportional to the resistance of the photosensitive element R(E_V,T), that changes with the intensity of the light E_v incident to the sensor material and its temperature T:

. _ fi las o^ut ~ R(E_V,T)

The spectrometer device may comprise at least means of cooling measures, e.g. at least one thermoelectric cooler (TEC). In this case of the temperature T can be neglected or can be assumed constant.

The read-out integrated circuit comprises at least one read-out element configured for determining an output current l_out of the photosensitive element. The read-out integrated circuit may comprises at least one read-out element selected from the group consisting of: at least one voltage divider circuit or at least one buffered direct injection circuit. The photosensitive element may be arranged between the bias voltage source and the read-out element such that the readout integrated circuit can determine an output current I_out of the photosensitive element.

The term “voltage divider circuit” 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 electronic circuit configured for generating an output voltage (7_0Ut) that is a fraction of its input voltage .

The term “buffered direct injection circuit”, also referred to as “B DI circuit”, 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 electronic device comprising at least one electrical circuit configured for providing a buffering function. Specifically, the BDI circuit may comprise a single electrical circuit or a set of electrical circuits, wherein at least one electrical circuit may comprise at least one feedback circuit, specifically at least one feedback circuit configured to reduce input impedance of the BDI circuit's input signal. To this end, the BDI circuit may comprise at least one buffer amplifier, such as at least one voltage buffer and/or at least one current buffer. For the measurement of the output current I_Pbs the photosensitive element may be arranged between V_Bias and V_BDI, wherein V_BDI is a regulated reference voltage (e.g. 2.6V), for which the upper equation results in: The BDI circuit may specifically be realized as an ASIC with multiple channels for read-out of a plurality of photosensitive elements in parallel. The term “application-specific integrated circuit (ASIC)” 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 integrated circuit configured for a specific use. Specifically, in the context of the present invention, the ASIC is configured for synchronous sampling the detector signals from the plurality of photosensitive elements. The term “sampling” 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 process of obtaining measurement values from a continuous-time signal. Specifically, the sampling may comprise obtaining measurement values, such as the detector signal from a continuous-time signal provided to the BDI circuit, specifically to the ASIC. The continuous-time signal may comprise an electrical signal by the detector, such as a photocurrent depending on the intensity of the incident light on the detector. The term “synchronous” 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 property of two or more processes being performed in an at least partially timely overlapping fashion. Specifically, the synchronous performing of two or more processes may comprise simultaneously starting and completing the two or more processes or, alternatively, starting at least one processes before at least one other processes, wherein, further, the at least one other processes may be started before the previously started process is completed. The synchronous sampling of the detector signals may comprise reading out of the detector signals in an at least partially timely overlapping fashion, specifically simultaneously. For example, the synchronous sampling of the detector signals may comprise reading out of the detector signals in parallel.

The read-out application-specific integrated circuit may comprise at least one skimming circuit configured for current skimming of a current at the detector. The term “skimming circuit” 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 electrical circuit configured for current skimming, specifically for removing a part of a current in another electrical circuit. Specifically, the skimming circuit may be configured for skimming the current at the detector, i.e. the detector current. As outlined above, the detector signal may specifically comprise the detector current indicating an accumulated photocurrent from the detector. Thus, the skimming circuit may act as a current sink, specifically as a current sink of the detector current. The skimming circuit may be comprised by at least one channel of the read-out integrated circuit, specifically of the read-out application-specific integrated circuit (ASIC), configured for read-out of the detector signal. The skimming circuit may specifically be optional. For example, in case the light source comprises the LED, no skimming circuit may be required. In this case, an input voltage to the BDI circuit may be in the range of the forward LED voltage and, thus, skimming may not be required. However, in other cases, such as other light sources, wherein the BDI input voltage may be lower than the voltage applied to the light source, for example 0 V, the skimming circuit may be advantageously used in the ASIC in order to remove the DC component of the voltage applied to the light source. The skimming circuit may specifically comprise at least one programmable current sink comprising at least one transistor. For example, the transistor may be used for a global skimming. The transistor may be configured for skimming an identical current of each channel. The skimming circuit may comprise a plurality of transistors. The transistors of the plurality of transistors may be used for a local skimming. For example, the transistors may be selectable for the channels. For example, the local skimming may be used for selecting specific channels for skimming and for neglecting other channels. This may allow measuring LEDs and detectors at the same time. The transistors may be of the same size and may be build-up in parallel, specifically equally weighted transistors when programmed, or, alternatively, of doubling size build-up in series, specifically binary weighted when programmed.

An exemplary channel of the read-out integrated circuit comprises the BDI circuit and may be configured for read-out of the detector signal. An input of the BDI circuit may be connected with an output of the detector, specifically with an output of a pixel of the detector. By applying a bias voltage Ve^to the BDI circuit, a voltage applied to the detector may be kept constant. The multichannel read-out integrated circuit may additionally comprise an analog to digital converter (ADC). Any change in the detector resistance due to the illumination may lead to an increased current flow, which may be digitalized by the analog to digital converter. Optionally, the ROIC may comprise the at least one skimming circuit configured for current skimming of the current at the detector, specifically to remove any offset in the signal, specifically in case the light source may comprise a light source other than the LED.

In real electrical systems all voltages are noisy and in this case noise on V_Bias and/or on V_BDI can be seen directly in the output signal which reduces the signal to noise ratio (SNR) of the signal. For increasing the SNR the voltages V_Bias and V_BDI must be as clean as possible and therefore the noise must be blocked on the physical level. To block the noise on the voltages additional parts would be needed in the application like e.g., capacitors or active filters. Those parts, however, need space which can be critical for electrical circuits with high integration density and furthermore increase costs. Generally, two different kinds of noise can occur on V_Bias and V_BDI the so called common mode noise and the so called differential mode noise. In the common mode noise, both voltages may be influenced by the same noise voltage V_Noise wherein it is assumed, that the bias voltage and the BDI voltage can be split to an DC part without noise V_Biasoc and V_BD/DCand the noisy part V_BiaSNoise and V_BDlNoise. The voltage difference may keep the same for common mode distortion, such that the detector shows no noise. In the differential mode, V_BDI is assumed to be constant, as it is regulated. V_Bias is noisy and it is assumed, that it can be split to an DC part without noise V_BlaSDC and the noisy part V_BiaSNoise. Thus, if there is differential noise in the system, this noise would falsifying the resulting current flowing out of the measurement cells, which is degreasing the SNR. In known devices, the noise part can only be reduced by said methods of filtering the signal which results in additional parts and higher costs. Again, it shall be noted that the term “noise” is used as synonym for any disturbance of the named voltage. Thus, not only in particular noise but voltage fluctuations in general may be compensated. Possible interferences may be one or more of noise, control deviations, switching power supply oscillations, conducted disturbance, radiated disturbance, magnetically coupled disturbance.

The present invention proposes that the read-out integrated circuit is configured for monitoring V_Bias. The bias voltage may have a strong influence on the quality of the optical measurement. Thus, by monitoring the bias voltage, the exact input voltage to the measurement system is known, which needs no longer to be assumed as constant. In known spectrometer devices, for the optical measurements V_Bias is assumed to have a constant preset value and no noise or drift. By knowing the input, or more exactly the noise on the input, the coherent noise on the output signal can be compensated in post processing. Therefore, the present invention can allow increasing reliability of the optical measurement, in particular by allowing plausibility checks and/or device health checks.

The measurement channel comprises a reference resistor having a known resistance R_Ref. The term “reference resistor” 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 resistor having a known resistance. The read-out element is configured for measuring a current I_Ref through the reference resistor. The resistance R_Ref may be an average value determined, specifically pre-determined, from a plurality of reference measurements. The reference resistor may be more robust compared to the detector, e.g. in view of one or more of temperature stability (low temperature coefficient), negligible hysteresis (high stability), negligible degradation with time (very low resistor aging), may have low noise and the like. The reference resistor may be or may comprise at least one resistor selected from the group consisting of M ELF, a metal foil resistor, a metal oxide resistor, a wire wound resistor, a carbon film resistor. The resistance R_Ref may be in the order of magnitude of R(E_V ). The resistance R_Ref may be from 100 k to 1 G , preferably from 1 MQ to 10 MQ. The reference resistor may be placed in parallel to the photosensitive element(s) and may be also connected between the bias voltage V_Bias and the regulated voltage V_BD1. The same bias voltage may be applied to both, the photosensitive element and the reference resistor. The current l_Ref through this resistor R_Ref may be measured with the same elements as the current through the photosensitive element(s).

The method comprises evaluating the output current I_out of the photosensitive element and deriving the spectroscopic information on the object therefrom by using the evaluation unit. The evaluating comprises considering the current I_Ref through the reference resistor. 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 and to generate at least one output thereof.

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.

The evaluation unit may be adapted to execute at least one computer program, such as at least one computer program performing or supporting the step b. of the method. As an example, one or more algorithms may be implemented which, by using the at least one detector signal I_out as input variable, may perform a predetermined transformation for deriving the spectroscopic information on the object, such as for deriving a corrected spectrum and/or for deriving at least one spectroscopic information describing at least one property of the object. For this purpose, the evaluation unit may, particularly, comprise at least one data processing device, also referred to as a processor, in particular an electronic data processing device, which can be designed to generate the desired information by evaluating the detector signal and the item of information on the at least one electrically measureable quantity. The evaluation unit may use an arbitrary process for generating the required information, such as by calculation and/or using at least one stored and/or known relationship. The evaluation unit specifically may be configured for performing at least one digital signal processing (DSP) technique on the primary detector signal or any secondary detector signal derived thereof, in particular at least one Fourier transformation. Additionally or alternatively, the evaluation unit may be configured for performing one or more further digital signal processing techniques on the primary detector signal or any secondary detector signal derived thereof, e.g. windowing, filtering, Goertzel algorithm, cross-correlation and auto-correlation. Besides the detector signal and the information on the at least one electrically measureable quantity, one or a plurality of further parameters and/or items of information can influence said relationship. The relationship can be determined or determinable empirically, analytically or else semi-empirically. As an example, the relationship may comprise at least one of a model or calibration curve, at least one set of calibration curves, at least one function or a combination of the possibilities mentioned. One or a plurality of calibration curves can be stored for example in the form of a set of values and the associated function values thereof, for example in a data storage device and/or a table. Alternatively or additionally, however, the at least one calibration curve can also be stored for example in parameterized form and/or as a functional equation. Separate relationships for processing the detector signals into the items of information may be used. Alternatively, at least one combined relationship for processing the detector signals is feasible. Various possibilities are conceivable and can also be combined.

The method may comprise determining an actual value of the bias voltage V_Bias,_actuai using the current I_Re through the reference resistor by using the at least one evaluation unit.

In particular, in step b., the following equations are used:

The bias voltage V_BiaSiactuai may be determined by measuring the current I_Ref through the reference resistor having the known resistance R_Ref-.

By knowing the actual present voltage V_BiaSiactuai over the resistor R_Ref via measuring the current I_Ref and therefore over the photosensitive element, the value of the electral resistance of the photosentive element R can be calculated with higher accurancy and therefore the SNR can be increased. In step b, the evaluation unit may calculate the electrical resistance R by _ (yBiasDc^+VBiasfi_0ise') lout

Additionally, the waveform of V_{B ias} can be evaluated. Ideally it should be constant. I_Ref and I_out may be measured simultaneously, such that for every moment the exact value of V_{B ias}, actual ^is known.

The evaluation unit may consider the actual value of the bias voltage V_Bias, actual f°^r compensating for noise for obtaining the spectroscopic information on the object. The spectroscopic information on the object may be compensated for noise considering the calculated electrical resistance R. By knowing the noise on the input of the detector, the noise on the optical output is also known and can be compensated in post processing, e.g. by one or more of kick out noisy parts, correct the noisy samples, remove the drift, and the like. For example, the resistance calculation may be used as plausibility check or device health check and not for the spectral measurement itself. Additionally or alternatively, in step b, the evaluation unit may calculate the electrical resistance R by

The electral resistance R may be calculated from ratios of the currents I_Ref and I_out. As the voltage (V_BiaSDC + V_BiaSNoise) are the same and the measurement of both the signal measurement and the measurement of the bias votlage take place in parallel and therefore exactly at the same time, both equations can be set in ratio over this voltage:

This equation is completly independent of the bias voltage and the noise. The resistor value can be choosen and a part with a very low deviation tolerance can be ordered. The currents can be measured with high resolution, e.g. with BDI and integrate and fire stage. Thus, by adding one resistor the calcualtion of the restence of the PbS-measurement cell is independent of the bias voltage and the noise on it and can be expressed as a ratio of measured currents and a fixed resistor value.

This resistor may require less space than any filtering circuit. Moreover, even a resistor with very low deviation tolerance may be less expensive than a filter circuit. So by adding one resistor to the system the SNR can be increased.

The bias voltage may be monitored for any noise components in the read-out circuit, which is also responsible to measure the signals of the mentioned detectors by means of simultaneous measurements. Thus, the noise components may be identical for bias voltage measurement and detector measurement. By simultaneously measuring the bias voltage, the present invention may allow to establish a correlation between the noise components on the bias voltage and the noise components on the detector output current. Therefore, by knowing input and its impact on the output it may be possible to compensate the noise and the SNR can be increased. The spectroscopic information on the object may be determined considering the calculated electrical resistance R. In particular, in this case, the noise on the optical output is known and can be compensated in post processing, e.g. by one or more of kick out noisy parts, correct the noisy samples, remove the drift, and the like.

The evaluation unit, specifically may be configured, e.g. by software programming, for determining at least one correction from the actual value of the bias voltage V_Bias, actual and/or the calculated resistance R. As an example, the evaluation unit may be configured for determining a spectrum from the at least one detector signal provided by the detector, such as a spectrum indicating a photometric or radiometric parameter as a function of the wavelength. This spectrum may be corrected by applying at least one correction function, e.g. a correction factor, e.g. a wavelength-dependent correction factor of correction function, to the spectrum, thereby generating a corrected spectrum. Thus, as an example, the correction factor specifically may be or may comprise at least one correction factor being a function of at least a wavelength of the detection light and the actual value of the bias voltage V_{Bias actuai} and/or the calculated resistance R. The detector signal may, as an example, provide a signal as a function of the wavelength of the detection light, wherein, by using the correction factor, each functional value of the detector signal may be multiplied with a corresponding correction factor, being determined by the actual value of the bias voltage V_Bias,_actual and/or the calculated resistance R.

The output current l_out of the photosensitive element may be corrected using l_ref, thereby determining an actual output current lout, actual. The actual output current may be used for further obtaining the spectroscopic information of the object.

The evaluation unit may be configured for evaluating the detector signal I_out generated by the detector and for deriving the spectroscopic information on the object from the detector signal.

As an example, the detector signal may comprise a plurality of detector signals being at least a function of the wavelength of the detection light, and, optionally, also of time, specifically for time-dependent detector signals. This plurality of detector signals may form a spectrum, including the option of a digital or an analogue spectrum. Thus, as an example, each of the detector signals may summarize information from a predetermined spectral range being defined by a spectral resolution of the detector. As outlined above, the detector may comprise a plurality of photosensitive elements, each of the photosensitive elements being sensitive in a different spectral range and/or being exposed to a different part of the spectrum of the detection light. The entirety of the detector signals of the photosensitive elements may form the detector signal, or in the entirety, as an example, defines the spectral information, a part thereof, or a predecessor thereof. Since the spectral range of sensitivity of each of the photosensitive elements may be known, the intensity of the detection light as a function of the detection wavelength may be derived by this detector signal, by combining the data pairs of the photosensitive elements, each data pair comprising the respective signal of the photosensitive element and the wavelength of sensitivity. Each of the respective signals of the photosensitive elements may be corrected by using a corresponding correction factor of the respective wavelength, wherein the correction factor, being a function of the actual bias voltage and/or the electrical resistance R is provided by the evaluation unit. It shall be noted, however, that other ways of generating spectral information are also feasible, such as by sequentially exposing one and the same detector to different spectral portions of the detection light, e.g. by using a scannable wavelength-selective element. The correction of these sequentially determined spectra may be performed in an analogous fashion, by using correction factors being a function of the wavelength, and by correcting the spectrum accordingly.

As outlined above, the detector may comprise a plurality of photosensitive element, specifically an array of photosensitive elements, wherein each of the photosensitive elements may be configured for generating at least one detector signal. The evaluation unit may be configured for individually considering the item of information on the electrically measurable quantity required for driving the light source for each of the detector signals of the photosensitive elements and for combining the detector signals for deriving the spectroscopic information. Specifically, the spectrometer device may be configured such that the photosensitive elements are sensitive to differing spectral ranges of the light from the object. For example, the spectrometer device may comprise at least one wavelength-selective element disposed in a beam path of the detection light. The wavelength-selective element may be configured such that each of the photosensitive elements is exposed to an individual spectral range of the detection light from the object.

The spectrometer device may comprise at least one wavelength-selective element. The wavelength-selective element may comprise at least one of a wavelength-selective element disposed in a beam path of the illumination light and a wavelength-selective element disposed in a beam path of the detection light. The wavelength-selective element may be selected from the group of a tunable wavelength-selective element and a wavelength-selective element having a fixed transmission spectrum. The wavelength-selective element having a fixed transmission spectrum may comprise at least one filter element, specifically at least one absorption filter element, more specifically a bandpass filter element. The tunable wavelength-selective element may comprise at least one tunable interferometer, specifically at least one of a MEMS Fabry-Perot interferometer and a MEMS Michelson interferometer.

The method, specifically at least step b. of the method, may be computer-implemented. The term “computer-implemented” 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 process which is fully or partially implemented by using a data processing means, such as data processing means comprising at least one processing unit. The method, specifically step b., may be computer-implemented, or at least computer-controlled or computer-assisted, by using the evaluation unit of the spectrometer device.

In a further aspect of the present invention, a computer program is disclosed, comprising instructions which, when the program is executed by a spectrometer device according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below, cause the spectrometer device to perform the method according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below.

Similarly, a computer-readable storage medium, specifically a non-transient computer-readable medium, is disclosed, comprising instructions which, when the instructions are executed by a spectrometer device according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below, cause the spectrometer device to perform the method according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below. As used herein, the terms “computer-readable data carrier”, “computer-readable storage medium” and “non-transient computer-readable medium” are broad term and are to be given their ordinary and customary meaning to a person of ordinary skill in the art and are not to be limited to a special or customized meaning. The terms specifically may refer, without limitation, to data storage means, specifically non-transitory data storage means, such as a hardware storage medium having stored thereon computer-executable instructions. The computer-readable data carrier or storage medium or computer-readable medium specifically may be or may comprise a storage medium such as a random-access memory (RAM) and/or a read-only memory (ROM).

In a further aspect of the present invention, a spectrometer device is disclosed. For possible embodiments of the spectrometer device and for definitions of terms, reference is made to the description of the method above.

The spectrometer device comprises: at least one detector comprising at least one photosensitive element configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region; at least one read-out integrated circuit comprising at least one measurement channel, wherein the read-out integrated circuit comprises at least one bias voltage source configured for applying at least one bias voltage V_Bias to the photosensitive element, wherein the read-out integrated circuit comprises at least one read-out element configured for determining an output current I_out of the photosensitive element, wherein the measurement channel comprises a reference resistor having a known resistance R_Ref, wherein the readout element is configured for measuring a current I_Ref through the reference resistor; at least one evaluation unit for evaluating the output current I_out of the photosensitive element and for deriving the spectroscopic information on the object therefrom, wherein the evaluation unit is configured for evaluating the output current I_out of the photosensitive element and the current I_Ref through the reference resistor thereby estimating the noise for obtaining the spectroscopic information, wherein the spectroscopic information on the object is compensated for the bias voltage influence.

The spectrometer device may be configured for performing the method according to the present invention.

The spectrometer device may comprise a tunable spectrometer assembly, such as at least one tunable MEMS Fabry-Perot assembly with a single detector or at least one tunable MEMS Michelson interferometer with a single detector.

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.

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.

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.

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

Embodiment 1 . A method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object by using a spectrometer device, wherein the spectrometer device comprises at least one detector comprising at least one photosensitive element configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region, wherein the spectrometer device comprises at least one read-out integrated circuit comprising at least one measurement channel, wherein the read-out integrated circuit comprises at least one bias voltage source configured for applying at least one bias voltage V_Blas to the photosensitive element, wherein the read-out integrated circuit comprises at least one read-out element configured for determining an output current I_out of the photosensitive element, wherein the measurement channel comprises a reference resistor having a known resistance R_Ref, wherein the read-out element is configured for measuring a current I_Ref through the reference resistor, the method comprising the following steps: a. applying at least one bias voltage V_Bias to the photosensitive element by using the bias voltage source of the read-out integrated circuit, determining the output current I_out of the photosensitive element and measuring the current I_Ref through the reference resistor having the known resistance R_Ref, b. evaluating, by using at least one evaluation unit, the output current I_out of the photosensitive element and the current I_Ref through the reference resistor thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object is compensated for the bias voltage influence.

Embodiment 2. The method according to the preceding embodiment, wherein, in step b, the method comprises determining an actual value of the bias voltage V_Blas,_actuai using the current I_Ref hrough the reference resistor by using the evaluation unit, wherein the evaluation unit considers the actual value of the bias voltage V_BiaSiactuai for compensating for noise for obtaining the spectroscopic information on the object.

Embodiment 3. The method according to the preceding embodiment, wherein, in step b, the evaluation unit calculates the electrical resistance R by

Embodiment 4. The method according to any one of the two preceding embodiments, wherein the evaluation unit evaluates the output current I_out and the waveform of V_Bias, actual by using the current I_Ref through the reference resistor.

Embodiment 5. The method according to any one of the preceding method embodiments, wherein, in step b, the evaluation unit calculates the electrical resistance R by

Embodiment 6. The method according to any one of the two preceding embodiments, wherein the spectroscopic information on the object is compensated for noise considering the calculated electrical resistance R.

Embodiment 7. The method according to any one of the preceding embodiments, wherein the method comprises illuminating the object with illumination light generated by at least one light source.

Embodiment 8. The method according to any one of the preceding embodiments referring to a method, wherein at least step b. of the method is computer-implemented.

Embodiment 9. A spectrometer device for obtaining spectroscopic information on at least one object, the spectrometer device comprising:

- at least one detector comprising at least one photosensitive element configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region;

- at least one read-out integrated circuit comprising at least one measurement channel, wherein the read-out integrated circuit comprises at least one bias voltage source configured for applying at least one bias voltage V_Bias to the photosensitive element, wherein the read-out integrated circuit comprises at least one read-out element configured for determining an output current I_out of the photosensitive element, wherein the measurement channel comprises a reference resistor having a known resistance R_Ref , wherein the read-out element is configured for measuring a current I_Ref through the reference resistor;

- at least one evaluation unit for evaluating the output current I_out of the photosensitive element and for deriving the spectroscopic information on the object therefrom, wherein the evaluation unit is configured for evaluating the output current I_out of the photosensitive element and the current I_Ref through the reference resistor thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object is compensated for the bias voltage influence.

Embodiment 10. The spectrometer device according to the preceding embodiment, wherein the spectrometer device is configured for determining an actual value of the bias voltage ^Bias, actual using the current I_Ref through the reference resistor by using the evaluation unit, wherein the evaluation unit is configured for considering the actual value of the bias voltage V_{B las},_actuai for compensating for the bias voltage influence for obtaining the spectroscopic information on the object.

Embodiment 11 . The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the light-sensitive region comprises at least one photoconductive material selected from the group consisting of lead sulfide (PbS); lead selenide (PbSe); mercury cadmium telluride (HgCdTe); cadmium sulfide (CdS); cadmium selenide (CdSe); indium antimonide (InSb); indium arsenide (InAs); indium gallium arsenide (InGaAs); silicon (Si); Silicon Germanium (SiGe); extrinsic semiconductors, organic semiconductors.

Embodiment 12. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the spectrometer device comprises at least one light source for generating illumination light for illuminating the object.

Embodiment 13. The spectrometer device according to the preceding embodiment, wherein the light source is configured for emitting light in a spectral range at least partially comprising an infrared spectral range, specifically a near-infrared spectral range, more specifically in a spectral range from 760 nm to 3 pm, more specifically in a spectral range from 1 pm to 3 pm, more specifically in a spectral range from 1 pm to 2.5 pm, more specifically in a spectral range from 1 .3 pm to 2.5 pm, most specifically in a spectral range from 1.5 pm to 2.2 pm.

Embodiment 14. The spectrometer device according to any one of the two preceding embodiments, wherein the light source comprises at least one light source selected from the group consisting of: an incandescent lamp; a light emitting diode (LED); a laser, a laser diode, a solid-state laser, a gas laser, a quantum cascade laser, a plasma light source, e.g., low pressure fluorescent lamps, high pressure lamps, or any types of light source, which can be driven by means of electrical current and voltage.

Embodiment 15. The spectrometer device according to any one of the three preceding embodiments, wherein the light source comprising at least one light-emitting diode and at least one luminescent material for light-conversion of primary light generated by the light-emitting diode.

Embodiment 16. The spectrometer device according to any one of the four preceding embodiments, wherein the spectrometer device comprises at least one driving unit for electrically driving the light source.

Embodiment 17. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the read-out integrated circuit comprises at least one read-out element selected from the group consisting of: at least one voltage divider circuit or at least one buffered direct injection circuit.

Embodiment 18. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the photosensitive element is arranged between the bias voltage source and the read-out element such that the read-out integrated circuit can determine an output current I_out of the photosensitive element.

Embodiment 19. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the evaluation unit is configured for calculating the electrical resistance R by

Embodiment 20. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the evaluation unit is configured for evaluating the output current l_out and the waveform of V_Bias,act by using the current I_Ref through the reference resistor.

Embodiment 21 . The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the evaluation unit is configured for calculating the electrical resistance R by

Embodiment 22. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the read-out integrated circuit comprises at least one skimming circuit configured for current skimming of a current at the detector. Embodiment 23. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the detector comprises a plurality of photosensitive element, wherein each of the photosensitive elements is configured for generating at least one detector signal.

Embodiment 24. The spectrometer device according to the preceding embodiment, wherein the spectrometer device is configured such that the photosensitive elements are sensitive to differing spectral ranges of the light from the object, wherein the spectrometer device comprises at least one wavelength-selective element disposed in a beam path of detection light, wherein the wavelength-selective element is configured such that each of the photosensitive elements is exposed to an individual spectral range of the detection light from the object.

Embodiment 25. The spectrometer device according to any one of the two preceding embodiments, wherein the spectrometer device comprises multi-channel read-out integrated circuit comprising a plurality of measurement channels.

Embodiment 26. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the spectrometer device comprises a tunable spectrometer assembly, such as at least one tunable MEMS Fabry-Perot assembly with a single detector or at least one tunable MEMS Michelson interferometer with a single detector.

Embodiment 27. The spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, wherein the spectrometer device is configured for performing the method according to any one of the preceding embodiments referring to a method.

Embodiment 28. A computer program comprising instructions which, when the program is executed by the spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, cause the spectrometer device to perform the method according to any one of the preceding embodiments referring to a method.

Embodiment 29. A computer-readable storage medium, specifically a non-transient computer- readable medium, comprising instructions which, when the instructions are executed by spectrometer device according to any one of the preceding embodiments referring to a spectrometer device, cause the spectrometer device to perform the method according to any one of the preceding embodiments referring to a method.

Short description of the Figures 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.

In the Figures:

Figure 1 shows a schematic overview of a spectrometer device;

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

Figure 3 shows a flow chart of an embodiment of a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object by using a spectrometer device; and

Figure 4 shows a schematic view of an embodiment of a read-out integrated circuit of a spectrometer device.

Detailed description of the embodiments

In Figure 1 , a schematic overview of a spectrometer device 110 for obtaining spectroscopic information on at least one object 112 is shown. The spectrometer device 110 may comprise a plurality of components as illustrated in Figure 1. Possible components of the spectrometer device 110 and their interplay will be described in the following, specifically with reference to Figure 1 . The spectrometer device 110 may comprise at least one light source 114 for generating illumination light 116 for illuminating the object 112. The light source 114 may be at least one of a tunable light source, a light source having at least one fixed emission wavelength and a broadband light source. The light source 114 specifically may be or may comprise at least one electrical light source. The light source 114 may, as an example, comprise at least one lightemitting diode 118 and at least one luminescent material 120 for light-conversion of primary light generated by the light-emitting diode 118. As an example, the light-emitting diode 118, may comprise one or more of: a light-emitting diode (LED) based on spontaneous emission of light, a light-emitting diode based on superluminescence (sLED), a laser diode (LLED).

The LED 118 may specifically comprise at least two layers of semiconductor material 121 , wherein light may be generated at at least one interface between the at least two layers of semiconductor material 121 , specifically due to a recombination of positive and negative electrical charges. The at least two layers of semiconductor material 121 may have differing electrical properties, such as at least one of the layers being an n-doped semiconductor material 121 and at least one of the layers being a p-doped semiconductor material 121 . Thus, as an example, the LED 118 may comprise at least one pn-junction and/or at least one pin-set up. It shall be noted, however, that other device structures are feasible, too.

The light-emitting diode 118 may generate primary light, which may also be referred to as “pump light”. The primary light may subsequently be transformed into “secondary light”, such as by using light conversion, e.g. through one or more luminescent materials 120, such as phosphor materials. The at least one luminescent material 120, thus, may form at least one converter, also referred to as a light converter, transforming primary light into secondary light having different spectral properties as compared to the primary light. Specifically, a spectral width of the secondary light may be larger than a spectral width of the primary light, and/or a center of emission of the secondary light may be shifted, specifically red-shifted, compared to the primary light. Specifically, the at least one luminescent material 120 may have an absorption in the ultraviolet and/or blue spectral range and an emission in the near-infrared and/or infrared spectral range. The illumination light 116 may be or may comprise at least one of the primary light or a part thereof, the secondary light or a part thereof, or a mixture of both.

As indicated in Figure 1 , the light source 114 may specifically comprise a phosphor light-emitting diode 122, also referred to as phosphor LED 122. The phosphor LED 122 may be a combination of at least one light-emitting diode 118 configured for generating primary light or pump light, and at least one luminescent material 120, also referred to as a “phosphor”, configured for light-conversion of the primary light generated by the light-emitting diode 118. The phosphor LED 122 may form a packaged LED light source, including an LED die 124, e.g. a blue LED emitting blue pump light, as well as the phosphor, which, as an example, fully or partially coats the LED 118, which is, as an example, configured for converting the primary light or blue light into light having differing spectral properties, specifically into near-infrared light. Figure 2 shows a more detailed view of the light source 114 embodied as a phosphor LED 122.

Generally, the light source 114 can be embodied in various ways. Thus, the light source 114 can, for example, be part of the spectrometer device 110 in a housing 126 of the spectrometer device 110, as illustrated in Figure 1 . Alternatively or additionally, however, the at least one light source 114 can also be arranged outside the housing 126, for example as a separate light source 114 (not shown). The light source 114 can be arranged separately from the object 112 and illuminate the object 112 from a distance, as indicated in Figure 1.

Illumination light 116 as generated by the light source 114 may propagate from the light source 114 to the object 112. In Figure 1 , the illumination light 116 generated by the light source 114 and propagating to the object 112 is illustrated by an arrow. The object 112 specifically may comprise at least one sample, which may fully or partially be analyzed by spectroscopic methods.

As apparent from Figure 1 , the spectrometer device 110 further comprises at least one detector 128 comprising at least one of photosensitive element 134 configured for exhibiting an electrical resistance R dependent on its an illumination of its light-sensitive region. Specifically, the detector 128 may be configured for detecting detection light 130 from the object 112. While light propagating from the light source 114 to the object 112 may be referred to as illumination light 116, light propagating from the object 112 to the detector 128 may be denoted as “detection light” 130. In Figure 1 , the detection light 130 is illustrated by an arrow. The detection light 130 may comprise at least one of illumination light 116 reflected by the object 112, illumination light 116 scattered by the object 112, illumination light 116 transmitted by the object 112, luminescence light generated by the object 112, e.g. phosphorescence or fluorescence light generated by the object 112 after optical, electrical or acoustic excitation of the object 112 by the illumination light 116 or the like. Thus, the detection light 130 may directly or indirectly be generated through the illumination of the object 112 by the illumination light 116.

The detector 128 may be or may comprise at least one optical detector 132. The optical detector 132 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 128 is irradiated. More specifically, the optical detector 132 may comprise the at least one photosensitive element 134 and/or at least one other 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 detector 128, 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 128 or a sensitive area of the detector 128 is illuminated.

The detector 128 may comprise one single optically sensitive element or area or a plurality of optically sensitive elements or areas. As indicated in Figure 1 , the detector 128 may comprise at least one detector array, more specifically an array of photosensitive elements 134. Each of the photosensitive elements 134 may be configured for generating at least one detector signal. In particular, each of the photosensitive elements 134 may comprise at least a photosensitive area, which may be adapted for generating an electrical signal depending on the intensity of the incident light, wherein the electrical signal may, in particular, be provided to an evaluation unit 136 of the spectrometer device 110, as will be outlined in further detail below.

In case the detector 128 comprises the array photosensitive elements 134, the detector 128, may e.g. be selected from any known pixel sensor, specifically from a CCD chip or a CMOS chip. As an alternative, the detector 128 generally may be or comprise a photoconductor, in particular an inorganic photoconductor, especially PbS, PbSe, Ge, InGaAs, ext. InGaAs, InSb, or HgCdTe. As a further alternative it may comprise at least one of pyroelectric, bolometer or thermopile detector elements.

The spectrometer device 110 comprises at least one read-out integrated circuit 135 comprising at least one measurement channel 170 (not shown in Figure 1 ). An exemplary embodiment of the read-out integrated circuit 135 is shown in Figure 4. Thus, for a detailed description of the read-out integrated circuit 135, reference is made to the description of Figure 4. As will be outlined in further detail below, the read-out integrated circuit 135 comprises at least one bias voltage source 172 (not shown in Figure 1) configured for applying at least one bias voltage V_Bias to the photosensitive element 134. The read-out integrated circuit 135 further comprises at least one read-out element 174 (not shown in Figure 1) configured for determining an output current I_out of the photosensitive element 134. The measurement channel 170 comprises a reference resistor 182 (not shown in Figure 1) having a known resistance R_Ref. The read-out element 174 is configured for measuring a current I_Ref through the reference resistor 182.

The spectrometer device 110 comprises at least one evaluation unit 136 for evaluating the output current I_out of the photosensitive element 134 and for deriving the spectroscopic information on the object 112 therefrom. Further, the evaluation unit 136 is configured for evaluating the output current I_out of the photosensitive element 134 and the current I_Ref through the reference resistor 182 thereby estimating the bias voltage influence for obtaining the spectroscopic information. The spectroscopic information on the object 112 is compensated for the bias voltage influence.

The evaluation unit 136 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 144, 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 146 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 136 may comprise one or more data storage devices 148, as shown in Figure 1 . Further, the evaluation unit 136 may comprise one or more interfaces, such as one or more wireless interfaces and/or one or more wire-bound interfaces.

As shown in Figure 1 , the spectrometer device 110 may further comprise at least one driving unit 138 for electrically driving the light source 114. The driving unit 138 may be configured for providing an electrical current to the LED 118, specifically for controlling an electrical current through the LED 118. Therein, as an example, the driving unit 138 may be configured for adapting and measuring a voltage provided to the LED 118, the voltage being required for achieving a specific electrical current through the LED 118. The driving unit 138, specifically, may comprise one or more of: a current source 140, a voltage source, a current measurement device, such as an Ampere-meter, a voltage measurement device 142, such as a Volt-meter, a power measurement device. Specifically, the driving unit 138 may comprise at least one current source 140 for providing at least one predetermined current to the LED 118, wherein the current source 140 specifically may be configured for adjusting or controlling a voltage applied to the LED 118 in order to generate the predetermined current. The driving unit 138, as an example, may comprise one or more electrical components, such as integrated circuits, for driving the light source 114. The driving unit 138 may be fully or partially integrated into the light source 114 or may be separated from the light source 114, the latter configuration being illustrated in Figure 1 . As described above in more detail, the detector 128 may specifically comprise an array of photosensitive elements 134. Each of the photosensitive elements 134 may be configured for generating at least one detector signal. The evaluation unit 136 may be configured for individually correcting each of the detector signals and for combining the detector signals for deriving the spectroscopic information. The spectrometer device 110 may be configured such that the photosensitive elements 134 of the detector 128 are sensitive to differing spectral ranges of the light from the object 112. In particular, the detector 128 may be configured for generating detector signals for at least two differing spectral ranges of the light from the object 112, specifically at least one of sequentially and simultaneously. The spectrometer 110 specifically may comprise at least one filter element 150 disposed in a beam path of the light from the object 112. The filter element 150 specifically may be configured such that each of the photosensitive elements 134 is exposed to an individual spectral range of the light from the object 112.

The spectrometer device 110 further may comprise one or more optical components 151 , e.g. such as one or more of at least one mirror, at least one lens, at least one aperture and at least one wavelength-selective element 152. Specifically, the one or more optical components 151 may be arranged in at least one of the beam path of the illumination light 116 and the beam path of the detection light 130. The spectrometer device 110 may in particular comprise the at least one wavelength-selective element 152. The wavelength-selective element 152 specifically may be selected from the group of a tunable wavelength-selective element 152 and a wave- length-selective element 152 having a fixed transmission spectrum. By using a tunable wavelength-selective element 152, as an example, differing wavelength ranges may be selected sequentially, whereas, by using a wavelength-selective element 152 having a fixed transmission spectrum, the selection of the wavelength ranges may be fixed and may, however, be dependent e.g. on a detector position. The wavelength-selective element 152 may be used for separating incident light into a spectrum of constituent wavelength signals whose respective intensities are determined by employing a detector, e.g. the detector 128 of the spectrometer device 110, which may comprise the array of photosensitive elements 134. The at least one wavelength-selective element 152 may e.g. comprise at least one of a filter, a grating and a prism. The wavelength-selective element 152 may specifically comprise at least one of a wavelength-selective element 152 disposed in the beam path of the illumination light 116 and a wavelength-selective element 152 disposed in the beam path of the detection light 130. Figure 1 illustrates an embodiment of the spectrometer device 110 with one wavelength-selective element 152 arranged in the beam path of the illumination light 116, and one wavelength-selective element 152 arranged in the beam path of the detection light 130.

The spectrometer device 110 as represented in a schematic fashion in Figure 1 is configured for obtaining spectroscopic information on the at least one object 112. In particular, the spectrometer device 110 may be configured for obtaining an item of information, e.g. on the object 112 and/or radiation emitted by the object 112, characterizing at least one optical property of the object 112, 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 object 112. As an example, the spectroscopic 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 112, e.g. as a function of a wavelength or wavelength subrange over one or more wave-lengths, e.g. over a range of wavelengths. Thus, the spectrometer device 110 may be configured for acquiring at least one spectrum or at least a part of a spectrum of detection light 130 propagating from the object 112 to the detector 128. The spectrum may describe the radiometric unit of spectral flux, e.g. given in units of watt per nanometer (W / nm), or other units, e.g. as a function of the wavelength of the detection light 130. Thus, the spectrum may describe the optical power of light, e.g. in the NIR spectral range, in a specific wavelength band. The spectrum may contain one or more optical variables as a function of the wavelength, e.g. the power spectral density, electric signals derived by optical measurements and the like. The spectrometer device 110 may specifically be a portable spectrometer device 110, which may in particular be used in the field.

In Figure 2, a schematic cross-sectional view of a light source 114 is shown. The at least one light source 114 of the spectrometer device 110 may be configured for generating or providing to electromagnetic radiation in one or more of the infrared, the visible and the ultraviolet spectral range. Due to the fact that many material properties or properties on the chemical constitution of many objects 112 may be derived from the near infrared spectral range, light used for 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, more preferably of 1 pm to 2.5 pm, more preferably of 1 .3 pm to 2.5 pm, most preferably of 1.5 pm to 2.2 pm. The light source 114 may comprise the at least one light-emitting diode 118 and the at least one luminescent material 120 for light-conversion of primary light generated by the light-emitting diode 118. The LED 118 and the luminescent material 120, together, may form the phosphor LED 122, as described above.

The phosphor LED 122 as illustrated in Figure 2 may comprise one or more functional components. Specifically, the phosphor LED 122 may comprise one or more substrates 154, specifically one or more electrically insulating substrates 154. In particular, the phosphor LED 122 may comprise one or more ceramic substrates 156, as shown in Figure 2. The substrate 154 may be configured for holding the at least one LED die 124 and the at least one luminescent material 120. Further, the at least one substrate 154 may hold or comprise one or more components of electrical connectivity, such as one or more contact pads 158 as shown in Figure 2 and/or one or more electrical leads, such as one or more metallic contacts and/or one or more metallic leads. The substrate 154 may be configured to serve as a heat sink. Heat may be generated in the LED die 124, such as due to a limited conversion of electrical energy into photonic energy, as well as in the luminescent material 120, e.g. during the conversion process. Said heat may be dissipated in the substrate 154, such as in ceramic substrate.

As shown in Figure 2, the phosphor LED 122 may comprise the light-emitting diode 118. The light-emitting diode 118 may be configured for converting electrical current into primary light, such as blue primary light, using at least one LED chip and/or the at least one LED die 124 as illustrated in Figure 2. Specifically, p-n-diodes may be used. As an example, one or more LEDs 118 selected from the group of an LED 118 on the basis of indium gallium nitride (InGaN), an LED 118 on the basis of GaN, an LED 118 on the basis of InGaN/GaN alloys or combinations thereof and/or other LEDs 118 may be used. Additionally or alternatively, quantum well LEDs 118 may also be used, such as one or more quantum well LEDs 118 on the basis of InGaN. Additionally or alternatively, Superluminescence LEDs (sLED) and/or Quantum cascade lasers may be used. As further apparent from Figure 2, the phosphor LED may comprise the at least one luminescent material 120 configured for light-conversion of the primary light generated by the light-emitting diode 118. Various types of conversion and/or luminescence are known and may be used in the context of the present invention. Specifically, the luminescent material 120 may comprise at least one of: Cerium-doped YAG (YAG:Ce3⁺, or Y₃AI₅0i2:Ce³⁺); rare-earth- doped Sialons; copper- and alu-minium-doped zinc sulfide (ZnS:Cu,AI).

The luminescent material 120 specifically may form at least one layer. Generally, various alternatives of positioning the luminescent material 120 with respect to the light-emitting diodel 18 are feasible, alone or in combination. Firstly, the luminescent material 120, e.g., at least one layer of the luminescent material 120, such as the phosphor, may be positioned directly on the light-emitting diode 118, e.g. with no material in between the LED 118 and the luminescent material 120 or with one or more transparent materials in between, such as with one or more transparent materials, specifically transparent for the primary light, in between the LED and the luminescent material 120. Thus, as an example, a coating of the luminescent material 120 may be placed directly or indirectly on the LED 118 (not shown). Additionally or alternatively, the luminescent material 120, as an example, may form at least one converter body 160, such as at least one converter disk, which may also be referred to as converter platelet. The converter body 160 may be placed on top of the LED 118, e.g. by adhesive attachment of the converter body 160 to the LED 118, as illustrated in Figure 2. Additionally or alternatively, the luminescent material 120 may also be placed in a remote fashion, such that the primary light from the LED 118 has to pass an intermediate optical path before reaching the luminescent material 120 (not shown). Again, as an example, the luminescent material in the remote placement may form a solid body or converter body 160, such as a disk or converter disk. In the intermediate optical path, one or more optical elements may be placed, such as one or more of a lens, a prism, a grating, a mirror, an aperture or a combination thereof. Thus, specifically, an optical system having imaging properties may be placed in between the LED 118 and the luminescent material 120, in the intermediate optical path. Thereby, as an example, the primary light may be focused, or bundled onto the converter body 160.

In the light source 114, specifically the phosphor LED 122, the at least one luminescent material 120 may be located with respect to the light-emitting diode 118 such that a heat transfer from the light-emitting diode 118 to the luminescent material 120 is possible. More specifically, the luminescent material 120 may be located such that a heat transfer by one or both of thermal radiation and heat conduction is possible, more preferably by heat conduction. Thus, as an example, the luminescent material 120 may be in thermal contact and/or in physical contact with the light-emitting diode 118 as illustrated in Figure 2. Thereby, generally, a temperature of the luminescent material 120 and a temperature of the light-emitting diode 118 may be coupled.

As illustrated in Figure 2, the light source 114, specifically the phosphor LED 122, may comprise further components such as at least one side coat 162 covering at least one side, such as a top side, a bottom side and/or one or more lateral sides of at least of: the substrate 154, the contact pad 158, the light-emitting diode 118 and the luminescent material 120. Specifically, the side coat 162 may cover gaps and/or interspaces that may be present in the layered set-up of the light source 114 as shown in Figure 2. Further components of the light source 114, specifically components, which are not shown in Figure 2, are feasible. Generally, the light source 114, in particular the phosphor LED 122, may be packaged in one housing (not shown in Figure 2) or may be unpackaged. Thus, the LED 118 and the at least one luminescent material 120 for lightconversion of the primary light generated by the light-emitting diode 118 may specifically be housed in a common housing. Alternatively, however, the LED 118 may also be an unhoused or bare LED 118, as illustrated in Figure 2.

Figure 3 shows a flow chart of an exemplary embodiment of a method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object 112 by using a spectrometer device 110. In the method, a spectrometer device 110 according to the present invention, such as according to the exemplary embodiment shown in Figure 1 and/or according to any other embodiment of the spectrometer device 110 disclosed herein, may be used. Thus, for a description of the spectrometer device 110, reference is made to the description of Figure 1.

The method may comprise (denoted by reference number 164) illuminating the object 112 with illumination light 116 generated by the light source 114.

The method comprising the following steps: a. (denoted by reference number 166) applying at least one bias voltage V_Bias to the photosensitive element 134 by using the bias voltage source 172 of the read-out integrated circuit 135, determining the output current l_out of the photosensitive element 134 and measuring the current I_Ref through the reference resistor 182 having the known resistance RRef ’ b. (denoted by reference number 168) evaluating, by using the evaluation unit 136, the output current l_out of the photosensitive element 134 and the current I_Ref through the refer- ence resistor 182 thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object 112 is compensated for the bias voltage influence.

Specifically, the method may comprise determining an actual value of the bias voltage ^vBias, actual using the current I_Ref through the reference resistor 182 by using the evaluation unit 136. In particular, in step b., the following equations are used:

The bias voltage V_Bias,_actuai may be determined by measuring the current I_Re through the reference resistor 182 having the known resistance R_Ref

By knowing the actual present voltage V_BiaSiactuai over the resistor R_Ref 182 via measuring the current I_Ref and therefore over the photosensitive element 134, the value of the electral resistance of the photosentive element /? 134 can be calculated with higher accurancy and therefore the SNR can be increased. In step b, the evaluation unit 136 may calculate the electrical resistance R by

Additionally, the waveform of V_Bias can be evaluated. Ideally it should be constant. I_Ref and I_out may be measured simultaneously, such that for every moment the exact value of V_Bias, actual ^is known.

The evaluation unit 136 may consider the actual value of the bias voltage V_{BlaS Clctuai} for compensating for noise for obtaining the spectroscopic information on the object 112. The spectroscopic information on the object 112 may be compensated for noise considering the calculated electrical resistance R. By knowing the noise on the input of the detector 128, the noise on the optical output is also known and can be compensated in post processing, e.g. by one or more of kick out noisy parts, correct the noisy samples, remove the drift, and the like. For example, the resistance calculation may be used as plausibility check or device health check and not for the spectral measurement itself.

Additionally or alternatively, in step b, the evaluation unit 136 may calculate the electrical resistance R by

In Figure 4, an exemplary embodiment of an exemplary read-out integrated circuit 135 of the spectrometer device 110 is shown in a schematic view. As outlined above, the read-out integrated circuit 135 comprises at least one measurement channel 170. In the example of Figure 1 , specifically in case the detector 128 may comprise the plurality of photosensitive elements 134, the read-out integrated circuit 135 may be a multi-channel read-out integrated circuit comprising a plurality of measurement channels 170. Each of the measurement channels 170 may be configured for measuring the output current l_out of the associated photosensitive element 134. The multi-channel read-out integrated circuit may comprise at least one measurement channel 170 associated with each photosensitive element 134 and being specifically configured for read-out of the detector signal of the associated photosensitive element 134.

Further, the read-out integrated circuit 135 comprises at least one bias voltage source 172 configured for applying at least one bias voltage V_Bias to the photosensitive element 134. The readout integrated circuit 135 comprises at least one read-out element 174 configured for determining an output current l_out of the photosensitive element 134. As shown in Figure 4, the photosensitive element 134 may be arranged between the bias voltage source 172 and the read-out element 174 such that the read-out integrated circuit 135 can determine an output current I_out of the photosensitive element 134.

In the example of Figure 4, the read-out element 174 may be at least one buffered direct injection circuit 176. However, other read-out elements 174, such as voltage divider circuits or the like, are also feasible. Further, as can be seen in Figure 4, an input of the BDI circuit 176 may be connected with an output of the detector 128, specifically with an output of a pixel of the detector 128, more specifically with an output of the photosensitive element 134. By applying a bias voltage y_Biasto the BDI circuit 176, a voltage applied to the detector 128 may be kept constant. The read-out integrated circuit 135 may additionally comprise an analog to digital converter (ADC) 178. Any change in the detector resistance due to the illumination may lead to an increased current flow, which may be digitalized by the analog to digital converter 178. Optionally, the read-out integrated circuit 135 may comprise at least one skimming circuit 180 configured for current skimming of the current at the detector 128, specifically to remove any offset in the signal, specifically in case the light source 114 may comprise a light source other than the LED 118. Further, as shown in Figure 4, the measurement channel 170 comprises a reference resistor 182 having a known resistance R_Ref. The read-out element 174 is configured for measuring a current I_Ref through the reference resistor 182. The read-out element 174, as an example, may comprise an additional buffered direct injection circuit 186, wherein an input of the additional

BDI circuit 186 may be connected with an output of the reference resistor 182. The bias voltage Vfiiasmay also applied to the additional BDI circuit 186 for measuring the current I_Ref through the reference resistor 182.

List of reference numbers spectrometer device object light source illumination light light-emitting diode luminescent material semiconductor material phosphor light-emitting diode LED die housing detector detection light optical detector photosensitive element read-out integrated circuit evaluation unit driving unit current source voltage measurement device data processing devices preprocessing devices data storage devices filter element optical component wavelength-selective element substrate ceramic substrate contact pad converter body side coat illuminating the object applying at least one bias voltage evaluating the output current I_out and the current I_Ref measurement channel bias voltage source read-out element buffered direct injection circuit analog to digital converter skimming circuit reference resistor additional buffered direct injection circuit

Claims

1 . A method of compensating for a bias voltage influence for obtaining spectroscopic information on at least one object (112) by using a spectrometer device (110), wherein the spectrometer device (110) comprises at least one detector (128) comprising at least one photosensitive element (134) configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region, wherein the spectrometer device (110) comprises at least one read-out integrated circuit (135) comprising at least one measurement channel (170), wherein the read-out integrated circuit (135) comprises at least one bias voltage source (172) configured for applying at least one bias voltage V_{B las} to the photosensitive element (134), wherein the read-out integrated circuit (135) comprises at least one read-out element (174) configured for determining an output current I_out of the photosensitive element (134), wherein the measurement channel (170) comprises a reference resistor (182) having a known resistance R_Ref , wherein the read-out element (174) is configured for measuring a current l_Ref through the reference resistor (182), the method comprising the following steps: a. applying at least one bias voltage V_{B ias} to the photosensitive element (134) by using the bias voltage source (172) of the read-out integrated circuit (135), determining the output current I_out of the photosensitive element (134) and measuring the current I_Ref through the reference resistor (182) having the known resistance R_Ref ; b. evaluating, by using at least one evaluation unit (136), the output current I_out of the photosensitive element (134) and the current I_Ref through the reference resistor (182) thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectroscopic information on the object (112) is compensated for the bias voltage influence; wherein, in step b, the method comprises determining an actual value of the bias voltage vBtas, actual using the current I_Ref through the reference resistor (182) by using the evaluation unit (136), wherein the evaluation unit (136) considers the actual value of the bias voltage V_Bias>actuai for compensating for the bias voltage influence for obtaining the spectroscopic information on the object (112), wherein, in step b, the evaluation unit (136) calculates the electrical resistance R by

2. The method according to the preceding claim, wherein the evaluation unit (136) evaluates the output current l_out and the waveform of V_{B ias},_actuai by using the current I_Ref through the reference resistor (182).

3. The method according to any one of the preceding method claims, wherein, in step b, the evaluation unit (136) calculates the electrical resistance R by

4. The method according to any one of the two preceding claims, wherein the spectroscopic information on the object (112) is compensated for the bias voltage influence considering the calculated electrical resistance R.

5. The method according to any one of the preceding claims, wherein the method comprises illuminating the object (112) with illumination light (116) generated by at least one light source (114).

6. A spectrometer device (110) for obtaining spectroscopic information on at least one object (112), the spectrometer device (110) comprising: at least one detector (128) comprising at least one photosensitive element (134) configured for exhibiting an electrical resistance R dependent on an illumination of its light-sensitive region; at least one read-out integrated circuit (135) comprising at least one measurement channel (170), wherein the read-out integrated circuit (135) comprises at least one bias voltage source (172) configured for applying at least one bias voltage V_Bias to the photosensitive element (134), wherein the read-out integrated circuit (135) comprises at least one read-out element (174) configured for determining an output current I_out of the photosensitive element (134), wherein the measurement channel (170) comprises a reference resistor (182) having a known resistance R_Ref, wherein the read-out element (174) is configured for measuring a current l_Ref through the reference resistor (182); at least one evaluation unit (136) for evaluating the output current I_out of the photosensitive element (134) and for deriving the spectroscopic information on the object (112) therefrom, wherein the evaluation unit (136) is configured for evaluating the output current l_out of the photosensitive element (134) and the current I_Ref through the reference resistor (182) thereby estimating the bias voltage influence for obtaining the spectroscopic information, wherein the spectrometer device (110) is configured for determining an actual value of the bias voltage V_BiaS)actuat using the current I_Ref through the reference resistor (182) by using the evaluation unit (136), wherein the evaluation unit (136) is configured for considering the actual value of the bias voltage V_Btas, actual for compensating for the bias voltage influence for obtaining the spectroscopic information on the object (112), wherein the evaluation unit (136) is configured for calculating the electrical resistance R by

7. The spectrometer device (110) according to the preceding claim, wherein the read-out integrated circuit (135) comprises at least one read-out element selected from the group consisting of: at least one voltage divider circuit or at least one buffered direct injection circuit (176).

8. The spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110), wherein the photosensitive element (134) is arranged between the bias voltage source (172) and the read-out element (174) such that the read-out integrated circuit (135) can determine an output current I_0llt of the photosensitive element (134).

9. The spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110), wherein the evaluation unit (136) is configured for calculating the electrical resistance R by

10. The spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110), wherein the evaluation unit (136) is configured for evaluating the output current l_out and the waveform of V_BiaSiact by using the current I_Ref through the reference resistor (182).

11. A computer program comprising instructions which, when the program is executed by the spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110), cause the spectrometer device (110) to perform the method according to any one of the preceding claims referring to a method.

12. A computer-readable storage medium, specifically a non-transient computer-readable medium, comprising instructions which, when the instructions are executed by spectrometer device (110) according to any one of the preceding claims referring to a spectrometer device (110), cause the spectrometer device (110) to perform the method according to any one of the preceding claims referring to a method.