EP4673708A1

EP4673708A1 - Led temperature measurement setup via buffered direct injection (bdi) circuit

Info

Publication number: EP4673708A1
Application number: EP24706766.3A
Authority: EP
Inventors: Szu-Yu Huang; Samiul ISLAM; Henning ZIMMERMANN; Felix Schmidt; Celal Mohan OEGUEN; Tobias BAUMGARTNER; Till-Jonas Ostermann; Bernd Scherwath
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: WO2024180027A1; CN120712461A; JP2026507153A; KR20250155532A

Abstract

A spectrometer device (110) and a method of obtaining spectroscopic information on at least one object (112) are disclosed. The spectrometer device (110) comprises: i. at least one light source (114) for generating illumination light (116) for illuminating the object (112); ii. at least one detector (128) for detecting detection light (130) from the object (112) and generating at least one detector signal; iii. at least one driving unit (138) for electrically driving the light source (114); iv. at least one multi-channel read-out integrated circuit (139), wherein each channel of the multi-channel read-out integrated circuit (139) comprises at least one buffered direct injection (BDI) circuit (141), wherein the BDI circuit (141 ) is configured for read-out of the detector signal, wherein the BDI circuit (141) is configured for generating at least one item of information on an electrically measurable quantity required for driving the light source (114), wherein the multi-channel read-out integrated circuit (139) comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) (142) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source (114); and v. at least one evaluation unit (136) for evaluating at least one detector signal generated by the detector (128) and for deriving the spectroscopic information on the object (112) from the detector signal, wherein the evaluation unit (136) is configured for taking into consideration the item of information on the electrically measurable quantity required for driving the light source (114) when deriving the spectroscopic information from the detector signal.

Description

LED Temperature Measurement Setup via Buffered Direct Injection (BDI) Circuit

Technical Field

The present invention refers to spectrometer device for obtaining spectroscopic information on at least one object and to a method of 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 (QEx = 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.

US 10 841 563 B1 discloses a sensor and sensor platform, for an autonomous system. The sensor and its platform sense, perform signal or data processing, and make the decision locally at the point of sensing. More specifically, the sensor along with its platform simulates the hu- man-like or human capacity to make decisions by combing the data from several sensors that detect different data sets, and combine them in a series of data processes that allows autonomous decisions to be made. Additionally, the sensor platform combines multiple sensors in one metasensor with the functionality of multiple sensors placed on a common carrier or platform.

Tetzlaff T. et. al. describe in “Hardware Implementation of LED Forward Voltage Measurement for Junction Temperature Estimation”, 2018, 19th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), the extension of LED driver circuits by measurement components and signal processing hardware to accurately detect the LED junction temperature. This information can be used by the driver to control current and therefore the temperature of the LED device. Focus of this scientific publication is the measurement of the LED temperature based on the forward-volt- age measurement of the LED.

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 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 spectrometer device for obtaining spectroscopic information on at least one object, a method of obtaining spectroscopic information on at least one object, a computer program and a computer-readable storage medium, with the features of the independent claims. Advantageous embodiments which might be realized in an isolated fashion or in any arbitrary combinations are listed in the dependent claims as well as throughout the specification.

In a first aspect of the present invention, a spectrometer device for obtaining spectroscopic information on at least one object is disclosed.

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, comprises at least one light source which, 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.

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 comprises at least one light source for generating illumination light for illuminating the object.

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

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 to 3 pm, preferably from 1.3 to 2.5 pm, more preferably from 1 .5 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 a combination of the primary light and light generated by the light-conversion by the luminescent material or 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 further comprises at least one detector 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 ana- logue/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 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 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 lightemitting 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 multi-channel read-out integrated circuit. Each channel of the multi-channel read-out integrated circuit comprises at least one buffered direct injection (BDI) circuit. The BDI circuit is configured for read-out of the detector signal. The BDI circuit is configured for generating at least one item of information on an electrically measurable quantity required for driving the light source. The multi-channel read-out integrated circuit comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source.

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 of the detector 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. Additionally, the ROIC is configured for generating the item of information on an electrically measurable quantity required for driving the light source. The ROIC may have at least one channel for reading the detector, specifically at least one channel for each pixel of the detector, and at least one channel for generating the item of information on an electrically measurable quantity required for driving the light source, as will be outlined in further detail below.

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 multi-channel read-out integrated circuit may comprise at least two channels, such as at least one channel for read-out of the detector signal and at least one channel for generating the item of information on the electrically measurable quantity required for driving the light source. Consequently, the read-out integrated circuit comprising at least two channels may also be referred to as “multi-channel read-out integrated circuit”. The term “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 being associated with at least one component of the spectrometer device. Specifically, the multi-channel read-out integrated circuit may comprise at least one channel associated with the detector, the channel being specifically configured for read-out of the detector signal generated by the detector. Additionally, the multi-channel read-out integrated circuit may comprise at least one further channel associated with another component, such as a resistor, as will be outlined in further detail below, the channel being specifically configured for generating the item of information on the electrically measurable quantity required for driving the light source. As outlined above, the detector may comprise the plurality of photosensitive elements. In this case, the multi-channel read-out integrated circuit may comprise at least one channel associated with each photosensitive element and being specifically configured for read-out of the detector signal of the associated photosensitive element.

Each channel, as outlined above, comprises at least one B DI circuit. The term “buffered direct injection circuit”, also referred to as “BDI 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. The BDI circuit may specifically be realized as an ASIC with multiple channels for read-out of the detector and for generating the item of information on an electrically measurable quantity required for driving the light source for multiple channels in parallel.

The term “electrically measurable quantity” 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 parameter required for driving the light source, which is electrically measurable. Consequently, the term “item of information on an electrically measurable quantity” may refer to any numerical indication quantifying the electrically measurable quantity. For example, the item of information on the electrically measurable quantity required for driving the light source may comprise at least one item of information selected from the group consisting of: a forward voltage at the light source; a voltage drop at the light source; a current at the light source; an electrical power input at the light source; a resistance of the light source; an impedance of the light source.

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 signal and the item of information on the electrically measurable quantity required for driving the light source. Thus, the specific use of the ASIC may be synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source.

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 and/or the item of information on the electrically measurable quantity required for driving the light source, 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 and/or a photovoltage depending on the intensity of the incident light on the detector, and/or an electrical signal of the electrically measurable quantity required for driving the light source.

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 signal and the item of information on the electrically measurable quantity required for driving the light source may comprise reading out of the detector signal and generating the item of information on the electrically measurable quantity required for driving the light source in an at least partially timely overlapping fashion, specifically simultaneously. For example, the synchronous sampling of the detector signal and the item of information on the electrically measurable quantity required for driving the light source may comprise reading out of the detector signal and generating the item of information on the electrically measurable quantity required for driving the light source in parallel.

The multi-channel read-out application-specific integrated circuit (ASIC) 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 multi-channel read-out integrated cir- cuit, specifically of the multi-channel 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 one or more transistors, specifically a plurality of transistors. 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 multi-channel 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 an pixel of the detector. By applying a bias voltage y_Bjasto the BDI circuit, a voltage applied to the detector may be kept constant. The multi-channel 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, specifically the multi-channel read-out application-specific integrated circuit, 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.

Additionally or alternatively, an exemplary channel of the multi-channel read-out integrated circuit comprises the BDI circuit and may be configured for generating the item of information on the electrically measurable quantity required for driving the light source. As an example, the light source may comprise the LED. The spectrometer device may further comprise at least one resistor electrically connecting an anode of the LED with the ROIC. For example, the resistor may have a resistance in the range of IMfl to 10M , specifically of R = 2M(1. Additionally, the spectrometer device may comprise the shunt resistor. In this example, the spectrometer device may comprise at least two resistors, wherein the two or more resistors may be embodied similar with respect to each other, or, alternatively, different from each other. Each side of the shunt resistor may be electrically connected via one of the resistors to the multi-channel read-out integrated circuit. Thus, both a voltage drop at the shunt resistor and a current through the light source may be determinable. The shunt resistor, as an example, may have a resistance in the range of 1MH to 10MU, specifically of R = lfl.

The spectrometer device comprises at least one evaluation unit for evaluating at least one detector signal generated by the detector and for deriving the spectroscopic information on the object from the detector signal. The evaluation unit is configured for taking into consideration the item of information on the electrically measurable quantity required for driving the light source when deriving the spectroscopic information from the detector signal.

The term “to evaluate”, as used herein, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of processing at least one first item of information in order to generate at least one second item of information thereby. Consequently, the term “evaluation unit”, as used herein, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device or a combination of devices configured to evaluate or process at least one first item of information, in order to generate at least one second item of information thereof. Thus, specifically, the evaluation unit may be configured for processing at least one input signal and to generate at least one output signal thereof. The at least one input signal, as an example, may comprise at least one detector signal provided directly or indirectly by the at least one detector and, additionally, at least one signal directly or indirectly provided by the multichannel read-out integrated circuit, the signal specifically comprising the at least one item of information on the at least one electrically measureable quantity.

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 of generating the items of information. As an example, one or more algorithms may be implemented which, by using the at least one detector signal and the at least one item of information on the at least one electrically measureable quantity as input variables, 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 evaluation unit, specifically may be configured, e.g. by software programming, for determining at least one correction from the item of information on the at least one electrically measureable quantity. Thus, 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 at least one electrically measureable quantity. 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 at least one electrically measureable quantity.

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 at least one electrically measureable quantity, in particular the forward voltage, 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.

The spectrometer device may further comprise at least one resistor electrically connecting the light source with the multi-channel read-out integrated circuit. Specifically, in case the light source comprises the LED, the resistor may electrically connect an anode of the LED with the ROIC. Further, the spectrometer device may comprise at least two resistors and at least one shunt resistor. Each side of the shunt resistor may be electrically connected via at least one of the resistors to the multi-channel read-out integrated circuit. Thus, the voltage drop at the shunt resistor may be determined and a current through the light source may be determinable. The resistor and/or the shunt resistor may have a temperature coefficient smaller than 1000 ppm/K, specifically smaller than 100 ppm/K, more specifically smaller than 50 ppm/K, more specifically smaller than 10 ppm/K.

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.

Additionally or alternatively, the detector may comprise a single detector and the light source may comprise multiple light sources having different spectral ranges. Each of the light source may be configured for generating illumination light for illuminating the object in a specific spectral range. The detector may be configured for detecting detection light from the object, specifically comprising the reflected illumination light from the plurality of light sources in the different spectral ranges, and for generating at least one time-dependent detector signal. The evaluation unit may be configured for evaluating the time-dependent detector signal by frequency-multiplexing, specifically such that at least one detector signal for each of the different spectral ranges can be derived from the time-dependent detector signal. The detector signals for each of the different spectral ranges may be used for deriving the spectroscopic information on the object. Specifically, the evaluation unit may be configured for individually considering the item of information on the electrically measurable quantity required for driving the light sources for each of the detector signals and for combining the detector signals for deriving the spectroscopic information. Additionally or alternatively, it may be possible to use both the plurality of photosensitive element, as described above, and multiple light sources. The multi-channel read-out circuit may allow in both cases the synchronous sampling of the detector signal and the item of information on the electrically measurable quantity required for driving the light source.

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.

In a further aspect of the present invention, a method of obtaining spectroscopic information on at least one object by using 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 spectrometer device above.

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 comprises: a. electrically driving at least one light source by using at least one driving unit; b. illuminating the object with illumination light generated by the light source; c. generating at least one detector signal by detecting detection light from the object using at least one detector; d. generating at least one item of information on an electrically measurable quantity required for driving the light source by using at least one multi-channel read-out integrated circuit, wherein each channel of the multi-channel read-out integrated circuit comprises at least one buffered direct injection (BDI) circuit, wherein the BDI circuit is configured for read-out of the detector signal, wherein the BDI circuit is configured for generating the at least one item of information on an electrically measurable quantity required for driving the light source, wherein the multi-channel read-out integrated circuit comprises at least one multichannel read-out application-specific integrated circuit (ASIC) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source; and e. evaluating the at least one detector signal generated by the detector by using at least one evaluation unit and deriving the spectroscopic information on the object from the detector signal taking into consideration the item of information on the electrically measurable quantity required for driving the light source.

Specifically, in the method, 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, may be used.

Steps c. and d. may be performed in a timely overlapping fashion, specifically in parallel.

The method may be performed on-line in the field. The term “on-line”, 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 a process of being performed in the course of another process, such as during the other process, preferably without the necessity of being separately started or initiated by a user. Thus, specifically, the correction of the detector signal, by using the at least one item of information on the electrically measureable quantity may be performed as an on-line calibration or on-line correction during obtaining spectroscopic information on at least one object, without the necessity for performing a separate calibration process.

Further, in step e., at least one correction may be determined from the item of information on the electrically measurable quantity required for driving the light source, wherein, further, the at least one detector signal may be corrected, by using the correction. The correction may specifically comprise at least one temperature correction. The temperature correction may be at least partially dependent on the item of information on the electrically measurable quantity required for driving the light source. The correction may comprise multiplying the at least one detector signal with at least one correction factor. The corrected detector signal may be used for deriving the spectroscopic information.

The term “correction” 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 modification or the process of modifying at least one item of interest in accordance with one or more items of infer- mation indicating parameters known to have an impact on the item of interest. Thus, the measured spectrum may be corrected in such a way that the corrected spectrum corresponds to a spectrum under precisely known or standardized conditions, e.g. at a specific temperature and/or at a predetermined electrically measureable quantity. As an example, the correction may comprise a modification of a measured spectrum comprised by the detector signal to correspond to standardized conditions, such as at a predetermined electrically measureable quantity required for driving the light source and/or at a predetermined temperature. Thus, step e. may comprise a correction in which a measured spectrum derived from the detector signal may be modified to correspond to a corrected spectrum, specifically a corrected spectrum which presumably would have been obtained under predetermined standard conditions, e.g. at the predetermined electrically measureable quantity required for driving the light source and/or at a predetermined temperature. The standardized conditions may be defined by using appropriate conditions, e.g. by using room temperature as a predetermined temperature and/or using a specific measureable quantity required for driving the light source measured at a predetermined forward current at room temperature. Other standard conditions, however, are also feasible. Thereby, the corrected spectrum may be compared to a reference spectrum that is determined under the precisely known or standardized conditions.

For determining the correction factor, specifically the correction function, one or more calibration measurements may be performed. Thus, the correction may be based on one or more calibration measurements. As an example, the calibration measurements may determine the at least one detector signal, as a function of the electrically measureable quantity and, further, optionally also as a function of the detection wavelength. As outlined above, at least one condition may be determined as a standard condition, e.g., at least one specific electrically measureable quantity required for driving the light source. As an example, an electrically measureable quantity measured at room temperature may be predetermined to define standard conditions, e.g. for each wavelength. By determining a ratio between the detector signal measured for a specific electrically measureable quantity and the detector signal measured for the predetermined standard electrically measureable quantity, a correction factor may be determined for each wavelength. Thereby, specifically in case the item of information on the electrically measureable quantity indicates that the electrically measureable quantity deviates from the standard electrically measureable quantity, the correction factor may be chosen such that the corrected detector signal corresponds to a detector signal, which would have been measured if the conditions had been identical to the predetermined standard conditions, e.g. room temperature. Additionally or alternatively, the temperature may be varied in a targeted manner, such as to set or adjust the temperature to two or more target temperatures. Specifically, the standard conditions may comprise a set of two or more predefined target temperatures and/or a corresponding set of electrically measureable quantities. For each of the temperatures, the electrically measureable quantity and the detector signal may be measured, e.g. for each wavelength. Correction factors may then be determined as described above.

The correction specifically may be based on a model describing spectral properties of the light source as a function of the electrically measureable quantity and/or temperature. The model may be an empirical, semi-empirical or theoretical model. Thus, as an example, and as will be described in further detail below, the impact of a change in the electrically measureable quantity required for driving the light source on the spectrum may be measured in one or more calibration measurements, e.g. by using a standardized object or reference object and measuring the spectrum as a function of the electrically measureable quantity. Then, a correction may be determined, e.g. by using a specific electrically measureable quantity as a standard, and correcting spectra determined for other electrically measureable quantities to correspond to the standardized spectrum.

The at least one model describing modifications of the spectrum and/or of the spectroscopic information on the object as a function of the electrically measureable quantity and/or describing required corrections for correcting the spectrum and/or the spectroscopic information on the object as a function of the electrically measureable quantity may be predetermined, and may, as an example, be stored in at least one data storage device of the spectrometer device.

As further outlined above, the evaluation unit may be configured for correcting the at least one detector signal, by using the correction. Thus, as an example, the evaluation unit may be configured, e.g. by software programming, for directly or indirectly transforming the detector signal, e.g. a spectrum derived thereof, into a corrected detector signal, e.g. into a corrected spectrum. As an example and as further outlined above, the correction specifically may comprise multiplying the at least one detector signal, i.e. the “raw” detector signal or a secondary detector signal derived thereof, e.g. a spectrum generated by using the detector signal, with at least one correction factor. Thereby, a correction of the spectrum may be performed which takes into account the electrically measureable quantity required for driving the light source as a correction parameter. The evaluation unit specifically may be configured for using the corrected detector signal for deriving the spectroscopic information.

As an example, the detector may be configured for generating detector signals for at least one spectral range, specifically for at least two differing spectral ranges of the light from the object, specifically at least one of sequentially and simultaneously. For example, the detector, as outlined above, may comprise an array of photosensitive elements, wherein each photosensitive element may be sensitive in a different spectral range and/or may be exposed to light in a different spectral range. The evaluation unit may be configured for individually correcting the detector signals in differing spectral ranges and for combining the individually-corrected detector signals for deriving the spectroscopic information. Thereby, individually corrected detector signals may be combined e.g. for generating a corrected spectrum.

Thus, generally, the detector may comprise 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 generally be configured for individually correcting each of the detector signals and for combining the detector signals for deriving the spectroscopic information. Thus, specifically in case each of the photosensitive elements is sensitive in a different spectral range and/or is exposed to light in a different spectral range, e.g. by one or more appropriate filters in a beam path of the detection light, the impact of the electrically measureable quantity as a correction parameter and/or the impact of the temperature may be corrected individually for each of the photosensitive elements.

The method, specifically at least step e. 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 e., 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).

The spectrometer device and the method according to the present invention, in one or more of the above-mentioned embodiments and/or in one or more of the embodiments described in further detail below, provide a large number of advantages over known devices and methods of similar kind. Specifically, the spectrometer device and the method of obtaining spectroscopic information on at least one object provide minimal hardware effort for correcting for external and/or internal influences, such as temperature, in spectrometer device. The spectrometer device may provide a measurement device, which may allow the measurement of different physical quantities with small additional hardware adjustments and with high resolution based on the BDI circuit. One or more BDI circuits may be employed for read-out of the detector, specifically of one or more photoconductive detectors, and for generating the item of information on the electrically measurable quantity required for driving the light source. Such a multi-channel readout ASIC may allow a synchronous sampling of optical and electrical signals. Thus, for each optical measurement of the detectors, a corresponding measurement of other components may be performed and used for compensation. The ROIC may specifically comprise multiple channels comprising one or more BDI circuits. By applying a bias voltage V_Bias to the BDI circuit, the voltage applied to the detector may be kept constant. The current due to the applied voltage may be skimmed by means of current skimming to remove any offset in the signal. Any change in the detector resistance due to the illumination may lead to an increased current flow, which may be digitalized by an analog to digital converter (ADC) with a comparatively high time and voltage resolution. The bias voltage may be adjusted according to the measurement task.

In one example, the light source may comprise an LED. If a current at the LED may be regulated to a constant current I_set, specifically such that the LED stays on a constant level power output, a change in voltage is minimum in the chosen current range. For example, the current at the LED may be chosen such that the LED may have a forward voltage of 2.7 V to 2.9 V depending on a temperature. In the ROIC, the BDI's input voltage may be set to a steady 2.6 V. Thus, by connecting the resistor, specifically a resistor with a low temperature coefficient, between the anode of the LED and the input of the ROIC, it may be possible to analyze the item of information on an electrically measurable quantity required for driving the light source in the region of interest of about 0.1 V - 0.3 V with high precision. However, other input voltages may also be feasible for other light sources. Thus, the BDI may serve as an offset removal circuit.

Specifically, V_{LED dr}wer ~ ^Bias may be applied to the resistor, leading to a current which can be digitalized. Thus, only the change of the LED forward voltage due to a temperature change may be determined with high precision. As an example, a temperature may change from 20°C to 30°C. The voltage drop at the resistor may be determined according to R ~ ^LED driver ^Bias

VR,@3O°C = 2.7 V - 2.6 V = 100 mV

^,@20°c = 2.9 V - 2.6 V = 300 mV

By using an exemplary resistor of R = 2 MCI, measurement currents of 50nA to 150nA may be achieved. The ROIC may be configured to have a 24-bit resolution over this voltage and current range. Thus, in this example, a voltage and current resolution of I_res = 150 nA/2²⁴ = 8.9 fA and V_res = 300 mV/2²⁴ = 17.8 nV may be achieved.

Even though the absolute accuracy of the measurement voltage may deteriorate due to multiple confounds, e.g. tolerances on BDI voltage, resistance tolerance or the like, a relative change of the forward voltage may be monitored with high precision, which specifically may help to compensate any changes of the LED output power and, thus, may be used compensate any optical signal change of the detector.

In a further example, the spectrometer device may additionally comprise at least one shunt resistor to determine both the LED voltage drop and the LED current, wherein the input currents of the ROIC may be neglected. Thus, the electrical input power into the LED may be monitored in addition to the forward voltage, which may increase the precision with which the optical signal compensation ca be performed. This type of working mode may require matched read-out IC channels such that inherent offsets may not generate current offsets. Each side of the shunt resistor may be electrically connected via at least one of the resistor to the multi-channel read-out integrated circuit. This configuration may allow for high resolution, short-term, time-based power drift compensation methods, which, specifically, enable improved readings of the detector. The overall power measurement may not be very accurate, but the high resolution can be used for relative compensation methods. Additionally, if the thermal characteristics of the light source are known, such as thermal capacity and/or conductivity to PCB and/or conversion efficiency, the temperature of the light source may be estimated by the determined power dissipated over the light source.

Both measurement examples, specifically determining a forward voltage and/or a power measurement of the light source, may be performed at different stages of the lifetime of the spectrometer device, e.g. end of line test, open port measurements, measurements themselves, calibration measurements or the like. Additionally, when using multiple light sources, wherein potential drift effects can be common to all light sources or be individual to just a single light source, it may be possible to determine information if the drift happens in the ROIC or in the light sources themselves.

Additionally or alternatively, further types of light sources may also be monitored by means of the ROIC even if they feature different electrical and optical characteristics. As an example, the light source may comprise an incandescent light source. A filament of the incandescent lamp may be a metallic resistor. Thus, heating up pf the light source may follow Joule’s law and the emitted radiation may follow Planck’s law. By determining the current flowing through the filament and the voltage applied thereto, the resistance of the filament may be determined, wherein the latter may depend on the temperature. By keeping the resistance of the filament constant by means of control loops of current and voltage, the radiated spectrum from the light source may also be stabilized. This skimming current compensation may be used on forward voltage measurements as well as on power dissipation measurements.

Alternatively or additionally, negative thermal coefficient thermistors (NTC) may be used for direct temperature measurement. By positioning the NTC next to the light source or in direct contact to the light source and by determining the resistance of the NTC, it may be possible to monitor the temperature and consequently the optical output of the light source. The spectrometer device and the method according to the present invention may specifically allow fast sampling. Thus, the high frequency noise of the light source input by means of voltage and power measurements may be correlated to the light source output by means of the detector signal. By doing so, the signal to noise ratio of the measured detector signal can be increased.

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 spectrometer device for obtaining spectroscopic information on at least one object, the spectrometer device comprising: i. at least one light source for generating illumination light for illuminating the object; ii. at least one detector for detecting detection light from the object and generating at least one detector signal; iii. at least one driving unit for electrically driving the light source; iv. at least one multi-channel read-out integrated circuit, wherein each channel of the multi-channel read-out integrated circuit comprises at least one buffered direct injection (BDI) circuit, wherein the BDI circuit is configured for read-out of the detector signal, wherein the BDI circuit is configured for generating at least one item of information on an electrically measurable quantity required for driving the light source

(114), wherein the multi-channel read-out integrated circuit comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source (114); and v. at least one evaluation unit for evaluating at least one detector signal generated by the detector and for deriving the spectroscopic information on the object from the detector signal, wherein the evaluation unit is configured for taking into consideration the item of information on the electrically measurable quantity required for driving the light source when deriving the spectroscopic information from the detector signal.

Embodiment 2: 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 to 3 pm, preferably from 1 .3 to 2.5 pm, more preferably from 1.5 to 2.2 pm.

Embodiment 3: The spectrometer device according to any one of the 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, 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.

Embodiment 4: The spectrometer device according to any one of the 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 5: The spectrometer device according to any one of the preceding embodiments, wherein the item of information on the electrically measurable quantity required for driving the light source comprises at least one item of information selected from the group consisting of: a forward voltage at the light source; a voltage drop at the light source; a current at the light source; an electrical power input at the light source; a resistance of the light source; an impedance of the light source.

Embodiment 6: The spectrometer device according to any one of the preceding embodiments, wherein the multi-channel read-out application-specific integrated circuit (ASIC) comprises at least one skimming circuit configured for current skimming of a current at the detector. Embodiment 7: The spectrometer device according to the preceding embodiment, wherein the skimming circuit comprises at least one programmable current sink comprising one or more transistors, specifically a plurality of transistors, wherein the transistors are of the same size and are build-up in parallel or of doubling size build-up in series.

Embodiment 8: The spectrometer device according to any one of the preceding embodiments, further comprising at least one resistor electrically connecting the light source with the multi-channel read-out integrated circuit.

Embodiment 9: The spectrometer device according to any one of the preceding embodiments, further comprising at least two resistors electrically connecting the light source with the multi-channel read-out integrated circuit and at least one shunt resistor, wherein each side of the shunt resistor is electrically connected via at least one of the resistors to the multichannel read-out integrated circuit.

Embodiment 10: The spectrometer device according to any one of the two preceding embodiments, wherein the resistor and/or the shunt resistor have a temperature coefficient smaller than 1000 ppm/K, specifically smaller than 100 ppm/K, more specifically smaller than 50 ppm/K, more specifically smaller than 10 ppm/K.

Embodiment 11 : The spectrometer device according to any one of the preceding embodiments, wherein the detector comprises a plurality of photosensitive element, specifically an array of photosensitive elements, wherein each of the photosensitive elements is configured for generating at least one detector signal, wherein the evaluation unit is 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.

Embodiment 12: 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.

Embodiment 13: The spectrometer device according to the preceding embodiment, wherein the spectrometer device comprises at least one wavelength-selective element disposed in a beam path of the 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 14: The spectrometer device according to any one of the preceding embodiments, the spectrometer device further comprising at least one wavelength-selective element, the wavelength-selective element comprising 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.

Embodiment 15: The spectrometer device according to the preceding embodiment, wherein the wavelength-selective element is selected from the group of a tunable wavelength-selective element and a wavelength-selective element having a fixed transmission spectrum.

Embodiment 16: The spectrometer according to the preceding embodiment, wherein the wavelength-selective element having a fixed transmission spectrum comprises at least one filter element, specifically at least one absorption filter element, more specifically a bandpass filter element.

Embodiment 17: The spectrometer device according to any one of the two preceding embodiments, wherein the tunable wavelength-selective element comprises at least one tunable interferometer, specifically at least one of a MEMS Fabry-Perot interferometer and a MEMS Michelson interferometer.

Embodiment 18: A method of obtaining spectroscopic information on at least one object by using a spectrometer device, the method comprising: a. electrically driving at least one light source by using at least one driving unit; b. illuminating the object with illumination light generated by the light source; c. generating at least one detector signal by detecting detection light from the object using at least one detector; d. generating at least one item of information on an electrically measurable quantity required for driving the light source by using at least one multi-channel read-out integrated circuit, wherein each channel of the multi-channel read-out integrated circuit comprises at least one buffered direct injection (BDI) circuit, wherein the BDI circuit is configured for read-out of the detector signal, wherein the BDI circuit is configured for generating the at least one item of information on an electrically measurable quantity required for driving the light source, wherein the multi-channel read-out integrated circuit comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source; and e. evaluating the at least one detector signal generated by the detector by using at least one evaluation unit and deriving the spectroscopic information on the object from the detector signal taking into consideration the item of information on the electrically measurable quantity required for driving the light source.

Embodiment 19: The method according to the preceding embodiment, wherein a spectrometer device according to any one of the preceding embodiments referring to a spectrometer device is used. Embodiment 20: The method according to any one of the preceding embodiments referring to a method, wherein steps c. and d. are performed in a timely overlapping fashion, specifically in parallel.

Embodiment 21 : The method according to any one of the preceding embodiments referring to a method, wherein the method is performed on-line in the field.

Embodiment 22: The method according to any one of the preceding embodiments referring to a method, wherein, in step e., at least one correction is determined from the item of information on the electrically measurable quantity required for driving the light source, wherein, further, the at least one detector signal is corrected, by using the correction.

Embodiment 23: The method according to the preceding embodiment, wherein the correction comprises at least one temperature correction, the temperature correction being at least partially dependent on the item of information on the electrically measurable quantity required for driving the light source.

Embodiment 24: The method according to any one of the two preceding embodiments, wherein the correction comprises multiplying the at least one detector signal with at least one correction factor.

Embodiment 25: The method according to any one of the three preceding embodiments, wherein the corrected detector signal is used for deriving the spectroscopic information.

Embodiment 26: The method according to any one of the preceding embodiments referring to a method, wherein at least step e. of the method is computer-implemented.

Embodiment 27: A computer program comprising instructions which, when the program is executed by a 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 28: A computer-readable storage medium, specifically a non-transient computer- readable medium, comprising instructions which, when the instructions are executed by a 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 schematic flowchart illustrating generating and processing a detector signal;

Figure 4 shows a diagram representing a superposition of spectra of infrared radiation of a phosphor LED at various temperatures;

Figure 5 shows a diagram representing a change in emission power change as a function of temperature for a selected number of wavelengths;

Figure 6 shows a diagram of a forward voltage as a function of temperature for a selected current;

Figures 7 A and 7B show spectra of two different types of phosphor LEDs;

Figures 8A and 8B show diagrams representing decay constants (Figure 8A) and growth constants (Figure 8B) as a function of wavelength for a phosphor LED emitting between 1 .3 pm and 2 pm;

Figure 9A and 9B show diagrams representing decay constants (Figure 9A) and growth constants (Figure 9B) as a function of wavelength for a phosphor LED emitting between 1.6 pm and 2.1 pm;

Figure 10 shows a diagram representing normalized light output as a function of a forward current;

Figure 11 shows a flow chart of an embodiment of a method of obtaining spectroscopic information on at least one object by using a spectrometer device;

Figures 12A to 12D show different embodiments of exemplary channels of the ROIC; and Figure 13 shows a diagram with a current-voltage characteristic of a light-emitting diode (LED).

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 comprises 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 comprises at least one light-emitting diode 118 and at least one luminescent material 120 for light-conversion of primary light generated by the lightemitting 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 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 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 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 of optically sensitive 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 evaluation unit 136 for evaluating at least one detector signal generated by the detector 128 and for deriving the spectroscopic information on the object 112 from the detector signal. The detector 128 may directly or indirectly provide the detector signals to the evaluation unit 136. Thus, the detector 128 and the evaluation unit 136 may be directly or indirectly connected, as indicated by arrows in Figure 1. The detector signal may be used as a “raw” detector signal and/or may be processed or preprocessed before further use, e.g. by filtering and the like. Thus, the detector 128 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.

As shown in Figure 1 , the spectrometer device 110 further comprises at least one driving unit 138 for electrically driving the light source 114. Particularly, 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 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. 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 inte- grated 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 .

The spectrometer device 110 further comprises at least one multi-channel read-out integrated circuit 139. Each channel of the multi-channel read-out integrated circuit 139 comprises at least one buffered direct injection (BDI) circuit 141. The BDI circuit 141 is configured for read-out of the detector signal. The BDI circuit 141 is configured for generating at least one item of information on an electrically measurable quantity required for driving the light source 114. The multi-channel read-out integrated circuit 139 comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) 142 configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source 114. Possible embodiment of the multi-channel read-out integrated circuit 139 are shown in Figures 12A to 12D. Thus, for a detailed description of the ROIC, reference is made to the description of Figures 12A to 12D.

As outlined above, the BDI circuit 141 may be configured for generating the at least one electrically measurable quantity, in particular a forward voltage, required for driving the light source 114, specifically the light-emitting diode 118. The forward voltage may be applied to the LED 118 in the forward direction, i.e. with a positive contact of a voltage or current source 140 applied to a p-layer of the LED 118 and a negative contact applied to the n-layer of the LED 118, in order to generate a predetermined electrical current through the LED 118. As an example, the predetermined current defining the forward voltage may be a current, which is known to generate a predetermined light output of the light source 114 and/or of the light-emitting diode 118.

As outlined above, and as shown in Figure 1 , the spectrometer device 110 comprises the at least one evaluation unit 136 for evaluating at least one detector signal generated by the detector 128 and for deriving the spectroscopic information on the object 112 from the detector signal. The evaluation unit 136 is configured for taking into consideration the item of information on the at least one electrically measurable quantity, in particular the forward voltage, when deriving the spectroscopic information from the detector signal. Specifically, the evaluation unit 136 may be configured for processing at least one input signal and to generate at least one output signal thereof. The at least one input signal, as an example, may comprise at least one detector signal provided directly or indirectly by the at least one detector 128 and, additionally, at least one signal directly or indirectly provided by ROIC 139, the signal comprising the at least one item of information on the at least one electrically measurable quantity, in particular the forward voltage. The arrows between the driving unit 138, which at least partially comprises the ROIC 139 in the embodiment illustrated in Figure 1 , and the evaluation unit 136 in Figure 1 illustrate the process of providing to the evaluation unit 136 and/or retrieving by the evaluation unit 136 the signal comprising the at least one item of information on the at least one electrically measurable quantity, in particular the forward voltage. 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 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.

Specifically, the evaluation unit 136 may be configured, e.g. by software programming, for determining at least one correction from the item of information on the at least one electrically measurable quantity, in particular the forward voltage, specifically a correction based on a model describing spectral properties of the light source 114 as a function of the at least one electrically measurable quantity, in particular the forward voltage. The evaluation unit 136 further may be configured for correcting the at least one detector signal, by using the correction. The correction specifically may comprise multiplying the at least one detector signal with at least one correction factor as described in detail above and as will be described further below in an exemplary fashion. The evaluation unit 136 specifically may be configured for using the corrected detector signal for deriving the spectroscopic information.

As described above in more detail, the detector 128 may specifically comprise an array of photosensitive elements 134. Each of the photosensitive elements 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 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 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 wave- length-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 at least one object 112 and/or radiation emitted by the at least one 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 at least one object 112. 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 112, e.g. as a function of a wavelength or wavelength sub-range over one or more wavelengths, 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. Examples of spectra are shown e.g. in Figures 4, 7A and 7B. 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. The light source 114 comprises 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 122 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 Y3Al50i2:Ce³⁺); rare- earth-doped Sialons; copper- and aluminium-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 118 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 120 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 126 (not shown in Figure 2) or may be unpackaged. Thus, the LED 118 and the at least one luminescent material 120 for light-conversion of the primary light generated by the light-emitting diode 118 may specifically be housed in a common housing 126. Alternatively, however, the LED 118 may also be an unhoused or bare LED 118, as illustrated in Figure 2.

The schematic flowchart of Figure 3 illustrates the process of generating the detector signal as well as processing of the detector signal, e.g. to generate a corrected signal. Specifically, hardware components 164, which may take part in the process or generating and/or preprocessing the detector signal as well as software components 166, which may take part in processing and/or correcting the detector signal, are illustrated in Figure 3. The hardware components 164, also simply referred to as “hardware” 164, may specifically comprise the at least one light-emitting diode 118 of the spectrometer device 110, in particular a blue LED 118, configured for emitting blue primary light. The hardware components 164 may further comprise the luminescent material 120, also referred to as phosphor LED 122, the object 112 as well as one or more optical components 151 , e.g. the at least one wavelength-selective element 152, and the detector 128.

As part of the correction that may be performed by the evaluation unit 136, a correction for temperature changes may be performed, even for local temperature changes within the light source 114, which may have an impact on the emission characteristics of the light source 114. In addition to the hardware components 164, temperatures for selected hardware components 164 are indicated in Figure 3. The hardware components 164 may have differing or identical temperatures, e.g. depending on an arrangement of the hardware components 164, such as their relative positions and distances in the spectrometer device 110. Specifically, as described above, the temperature of the luminescent material 120 and the temperature of the light-emitting diode 118 may be coupled, e.g. due to heat transfer by one or both of thermal radiation and heat conduction between the light-emitting diode 118 and the luminescent material 120. Thus, in particular, the temperature of the LED 118, which may also be referred to as “7^”, and the temperature of the luminescent material 120, which may also be referred to as “ T^”, may be similar or even identical. In Figure 3, the temperature of the LED 118 is indicated with reference sign 168, the temperature of the luminescent material 120 is indicated with reference sign 170, and the temperature of the detector 128, also referred to as “7 ”, is indicated with reference sign 172.

The LED 118 may emit primary light when an electrical current flows through the LED 118, e.g. as a result of an appropriate voltage applied to the LED 118 by the driving unit 138 in order to generate a specific electrical current, such as a predetermined electrical current. A target signal St may be provided as indicated in Figure 3 by reference sign 174, e.g. to the driving unit 138, to drive the LED 118 to emit blue primary light. The target signal St 174 may in particular be a predetermined current value that is to be generated through the LED 118, e.g. by applying an appropriate voltage. The predetermined current value may in particular be in the range from 10 mA to 500 mA, more specifically in the range from 100 mA to 300 mA, e.g. a current value of 50 mA. Thus, the predetermined current may be known to generate a predetermined light output of the LED 118, such as blue primary light. The LED 118 may be at the temperature “T_Pn indicated by reference sign 168. The blue primary light may be converted by the luminescent material 120 into secondary light, such as into light in the infrared spectral range. The luminescent material 120 may be at the temperature “T_Ph indicated by reference sign 170. The illumination light 116 generated by the light source 114, which 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, may illuminate the object 112. For directing the illumination light 116, one or more optical components 151 , such as one or more mirrors, lenses, wavelength selective elements 152 or other optical components 151 may be used, e.g. by placing the optical components 151 in the beam path of the illumination light 116. The detection light 130 from the object 112, e.g. reflected light, may be directed to the detector 128. In the beam path of the detection light 130, again, optionally, one or more optical components 151 may be used. As an example, one or more wavelength-selective elements 152 may be used, such as one or more dispersive elements, e.g. for splitting the detection light 130 into its spectral components.

As described above in more detail, the detector 128 may e.g. comprise an array of photosensitive elements 134. Specifically, the detector 128 may be or may comprise a pixel sensor, such as a CCD chip or a CMOS chip, comprising a plurality of pixels arranged on the chip. As an example, each of the pixels may correspond to a predetermined spectral range, e.g. by being sensitive to the predetermined spectral range. The detector 128 may thus generate a detector signal S_Px,i 176, as indicated in Figure 3 by reference sign 176, comprising a plurality of detector signals. Thus, each of the plurality of detector signals may correspond to an electronic signal generated by one of the plurality of pixels of the detector 128. Each of the plurality of detector signals may e.g. be given as a numerical value corresponding to a number of counts of the respective pixel as measured e.g. during a predetermined time span. Thus, the detector signal Spx 176 may specifically be a function of the wavelength of the detection light 130, as indicated by the index “px”. The signal S_px,i 176 may further be a function of time, e.g. in the case of timedependent detector signals, as indicated by the index “i”.

The plurality of signals comprised by the detector signal S_px,i 176 may be generated simultaneously or in a temporally successive manner. The detector signal S_px.i 176 may be determined using readout electronics 178 as indicated in Figure 3. The detector signal S_px,i 176 may be processed, e.g. as part of the preprocessing and/or as part of further processing steps. As an example, the pixels comprised by the detector 128 may specifically be active pixel sensors, which may be adapted to amplify the electronic detector signal S_px,i 176, e.g. as part of a preprocessing process prior to further processing that may e.g. be performed by one or more of the software components 166.

The signal S_px,i 176 as generated by the detector 128 may also be referred to as “Frame signal S_px,i 176”. Figure 3 illustrates the process of providing the signal S_px,i 176 to one of the software components 166 with an arrow. Specifically, the software components 166 configured for processing and/or correcting the detector signal S_px.i, 176 may comprise at least one first software 180, which may also be referred to as “software 1”, and at least one second software 182, which may also be referred to as “software 2”. The first software 180 may be configured for performing at least one first processing step 184, also referred to as “processing 1 ”, on the detector signal S_px,i 176, such as by applying at least one algorithm to the detector signal S_px,i 176. Specifically, the first processing step 184 may comprise at least one correction of transient or timedependent effects. Thus, as an example, the first processing step 184 may comprise one or more of the following: a correction of the dark signal; a correction of dark signal drift; a correction of fluctuation effects; a correction of photodetector response for individual detector elements or individual time steps; a correction of environment-induced, e.g., temperature-induced changes of the photodetector response; an extraction of information for subsequent processing; an addition or multiplication with a parameter, which was generated from information on the at least one electrically measurable quantity, in particular the forward voltage, or on device temperature. The first software 180 may be configured for performing at least one further step comprising at least one fast Fourier transform 186 to the detector signal. Thus, as a result of applying the first processing step 184 and/or the fast Fourier transform 186 to the detector signal S_pX]i 176, a signal S_px 188, also referred to as “pixel signal S_px 188”, may be generated, which may no longer be a function of time. Specifically, the time dependency of the frame signal S_px,j 176 may be eliminated by one or more of the steps forming part of the first software component 1 while the wavelength dependency may still be present in the on signal S_px 188 as indicated by the index “pn”. Figure 3 further illustrates the process of providing the signal S_px 188 to the second software 182 with an arrow. The second software 182 may be configured for performing at least one second processing step 190, also referred to as “processing 2”, on the signal S_px 188, such as by applying at least one algorithm to the signal S_px 188, thereby generating at least one corrected signal S_px, _Corr 191 . Specifically, the second processing step 190 may comprise one or more of the following: a correction of the dark signal; a correction of dark signal drift; a correction of fluctuation effects; a correction of photodetector response for individual detector elements or individual time steps; a correction of environment-induced, e.g., temperature-induced changes of the photodetector response; an extraction of information for subsequent processing; a manipulation with at least one parameter, for example an addition or multiplication with a parameter, which was generated from information on the at least one electrically measurable quantity, in particular the forward voltage, or on device temperature. In particular, the corrected signal S_px, _COrr 191 may comprise a plurality of corrected signals, such as a plurality of corrected electronic signals. Each of the plurality of corrected signals may specifically correspond to a corrected number of counts of the respective pixel.

The spectrometer device 1 10 comprises the at least one evaluation unit 136 for evaluating the at least one detector signal generated by the detector 128 and for deriving the spectroscopic information on the object 112 from the detector signal. The evaluation unit 136 is configured for taking into consideration the item of information on the at least one electrically measurable quantity, in particular the forward voltage when deriving the spectroscopic information from the detector signal. The evaluation unit 136 may in particular be configured by software programming for evaluating and/or processing the detector signal as part of the first processing step 184 of the at least one first software 180. The evaluation unit 136 may specifically be configured for determining the at least one correction from the item of information on the at least one electrically measurable quantity, in particular the forward voltage, and may further be configured for correcting the at least one detector signal, by using the correction. Thus, the evaluation unit 136 may process and correct the signal S_px 188 to generate a signal S_px, j, _COrr, which may then e.g. be further processed such as by applying the fast Fourier transform 186.

Both the light-emitting diode 118 and the luminescent material 120 may be based on different materials and/or different compositions of materials, e.g. as described in more detail above, which, generally, may affect and influence the spectrum 192 of the phosphor LED 122. However, the spectrum 192 or the spectral properties of a specific phosphor LED 122 may change with temperature, even when being operated at a specific, predetermined current. These changes may include shifts of the emission peaks 193, broadening or narrowing of the spectrum 192, increases or decreases of the emission and the like. In many cases, however, the emission at some wavelengths is affected to a larger extent than the emission at other wavelengths. This effect is illustrated by the diagram shown in Figure 4, which represents a superposition of spectra 192 of infrared radiation of a phosphor LED 122 at various temperatures. Specifically, the diagram in Figure 4 shows the power spectral density (PDS) 194 in units of microwatt per nanometer (pW/nm) on the y-axis 196 as a function of the wavelength 198 given in nanometers on the x-axis 200. For the represented spectra 192 the temperature of the phosphor LED 122 generating the illumination light 116 ranges from 25°C to 50°C. Typically, there is within the spectrum 192, a specific central wavelength, where the power spectral density typically does not change with temperature. Each wavelength therefore typically has its own temperature coefficient, regarding to the increment/decrement of the power. Therefore, the shape of the spectrum 192 changes with temperature as apparent from Figure 4. To visualize this effect even more clearly, a number of four specific wavelength intervals, each centering around one of four specific wavelengths ranging across the spectrum 192 are indicated in Figure 4. The wavelength intervals are delimited by dashed lines. Specifically, the following four wavelengths and their respective intervals are marked with the following reference signs: 1643 nm is indicated by reference sign 202, 1750 nm is indicated by reference sign 204, 1802 nm is indicated by reference sign 206, and 1950 nm is indicated by reference sign 208,. For each of these wavelengths, the emission power change normalized to the emission power change at 25°C is shown in the diagram in Figure 5 as a function of temperature over a temperature range from 25°C to 50°C. In the diagram of Figure 5 the emission power change normalized to the emission power change at 25°C given in percent is shown on the y-axis 196 and represented by reference sign 219, while the temperature in °C, represented by reference sign 220, is indicated on the x-axis 200. The lines in the diagram in Figure 5 indicate fitted curves 236. As apparent from Figure 5, the emission power at the central wavelength of 1802 nm may change very little over the observed temperature range (that is, the emission power change is zero or close to zero), while the emission power change may change considerably for other wavelengths, e.g. for 1643 nm or 1953 nm.

When generating a specific current through a light-emitting diode 118, such as an electrical current at a specific, predefined value by applying to the light-emitting diode 118 a forward voltage, the appropriate forward voltage may be a function of the temperature of the light-emitting diode 118. Thus, when applying the same current to the light-emitting diode 118, the forward voltage of the LED 118 typically decreases while temperature increases. Each type of the LED 118 has its own characteristic forward voltage to temperature curve. Typically, the forward voltage of the LED 118 linearly decreases with rising temperature, such as with a slope in the range of 1 ■ 10^-4 to 1 ■ 10^-3 V/K. Figure 6 illustrates this relationship for a specific LED 118. In particular, the diagram of Figure 6 shows the forward voltage applied to an LED 118 for the generation of a direct current of 150 mA through the LED 118 as a function of the temperature of the LED 118. The forward voltage in the units of Volt is represented by reference sign 224 on the y-axis 196. The temperature in °C is indicated by reference sign 220 on the x-axis 200. As apparent from Figure 6, the forward voltage, in this case, decreases linearly with increasing temperature. The curve in Figure 6, may be described by the following equation:

U /_f = -0.00059 2.98 wherein (/^represents the forward voltage and T represents the Temperature. In the diagram in Figure 6, measuring points 221 represented by grey, filled circles are shown as well as a dashed line corresponding to the above given fitted curve 236. Instead of a relation and/or curve between the forward voltage and the temperature as described in an exemplary fashion above, a relation between another electrically measurable quantity required for driving the light source 114 and the temperature may be used, e.g. a fed in electrical power; a current, resistance, inductance, capacitance and the like.

Thus, by using the at least one electrically measurable quantity, in particular the forward voltage, as a correction parameter, an individual temperature correction of the spectrum 192 at the different wavelengths may be performed. Specifically, the evaluation unit 136 may be configured for individually correcting the plurality of detector signals of the detector signal S_px,i and for combining the individually-corrected detector signals for deriving the spectroscopic information. As outlined above, the individual correction may be performed by using the array of photosensitive elements 134, wherein each of the photosensitive elements may be configured for generating at least one detector signal and wherein each of the detector signals may individually be corrected by using the at least one electrically measurable quantity, in particular the forward voltage, as a correction parameter. Finally, the corrected detector signals may be combined for deriving the spectroscopic information.

For deriving the spectroscopic information on the object 112, specifically a spectrum, the spectrometer device 110, in particular the evaluation unit 136, may specifically take into account the characteristics of the luminescent material 120 used in the light source 114. As outlined in more detail above, the luminescent material 120 may be configured for absorbing primary photons generated by the light-emitting diode 118 and may, as a reaction, emit secondary photons instantaneously or after a delay or decay time. The signal or emission of the phosphor LED 122 after turning off the forward current may be described using equations (1) and (2) as described above.

Thus, characteristic for the luminescent material 120 may in particular be the decay constant _d 228, which may describe the typical time of an afterglow of the luminescent material 120, as well as the growth constant t_g, which may describe the typical time for reaching a saturation of the emission of converted light. The time constants t_d and r_g typically differ between different phosphor LEDs 122 and/or between different types of the luminescent material 120. Additionally, decay constant T_d and growth constant _g may depend on the wavelength. The time constants typically are extracted from step response of the optical signal by applying / shutting off the forward current. Figures 7A and 7B show spectra 192 of two different types of phosphor LEDs 122, which emit light in the near infrared range. Specifically the power spectral density is shown as a function of the wavelength, which is given in nm. As apparent from Figures 7A and 7B the spectra 192 of the two different phosphor LEDs 122 differ. Thus, as an example, the spectrum 192 shown in Figure 7B reflects a high emission in the range from 1850 nm to 1950 nm, while the emission in this region is negligible for the phosphor LED 122, whose spectrum 192 is shown in Figure 7A. The decay constant _d and the growth constant _g of the phosphor LED 122, whose spectrum is shown in Fig 7A, are given as a function of the wavelength in Figures 8A and 8B, respectively. The decay constant and the growth constant T_g of the phosphor LED 122, whose spectrum is shown in Fig 7B, are given as a function of the wavelength in Figures 9A and 9B, respectively. Specifically, Figures 8A and 9A show the respective decay constants _d in ms, indicated by reference sign 228, on the y-axis 196 versus the wavelength in nm 198 on the x-axis 200; and Figures 8B and 9B show the respective growth constants z_g in ms, indicated by reference sign 230, on the y-axis 196 versus the wavelength in nm 198 on the x-axis 200. Data points from different repetition measurements are marked in different shades of grey.

A further characteristic of the LED 118 is the light output power as a function of the forward current. Thus, generally, by increasing the forward current, specifically the input current, the power emitted by the LED 118 is increased. The shape, e.g. the slope, of the curve of the light output as a function of the forward current is characteristic to the individual LED 118. Figure 10 shows an example of such a curve. Specifically, in the diagram in Figure 10, the normalized light output 232 of a phosphor LED 122 is shown as a function of the forward current 234, which is given in Ampere.

Figure 11 shows a flow chart of an embodiment of a method of obtaining spectroscopic information on the object 112 by using the spectrometer device 110. Specifically, in the method, a spectrometer device 110 according to the present invention, such as according to the exemplary embodiment described with respect to Figure 1 and/or according to any other embodiment disclosed herein, may be used. Thus, for a detailed description of the spectrometer device 110 to be used in the method, reference is made to the description of Figure 1.

The method comprises: a. (denoted by reference number 238) electrically driving the light source 114 by using the driving unit 138; b. (denoted by reference number 240) illuminating the object 112 with illumination light 116 generated by the light source 114; c. (denoted by reference number 242) generating the at least one detector signal by detecting detection light 130 from the object 112 using the detector 128; d. (denoted by reference number 244) generating the at least one item of information on an electrically measurable quantity required for driving the light source 114 by using the at least one multi-channel read-out integrated circuit 139, wherein each channel of the multichannel read-out integrated circuit 139 comprises at least one buffered direct injection (BDI) circuit 141 , wherein the BDI circuit 141 is configured for read-out of the detector signal, wherein the BDI circuit 141 is configured for generating the at least one item of information on an electrically measurable quantity required for driving the light source 114, wherein the multi-channel read-out integrated circuit 139 comprises at least one multichannel read-out application-specific integrated circuit (ASIC) 142 configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source 114; and e. (denoted by reference number 246) evaluating the at least one detector signal generated by the detector 128 by using the evaluation unit 136 and deriving the spectroscopic information on the object 112 from the detector signal taking into consideration the item of information on the electrically measurable quantity required for driving the light source 114.

Specifically, as indicated in Figure 11 , steps c. and d. may be performed in a timely overlapping fashion, specifically in parallel.

Further, in step e., at least one correction may be determined from the item of information on the electrically measurable quantity required for driving the light source 114, wherein, further, the at least one detector signal may be corrected, by using the correction. The correction may specifically comprise at least one temperature correction. The temperature correction may be at least partially dependent on the item of information on the electrically measurable quantity required for driving the light source 114. The correction may comprise multiplying the at least one detector signal with at least one correction factor. The corrected detector signal may be used for deriving the spectroscopic information.

Figures 12A to 12D show different embodiments of exemplary channels of the ROIC 139. Specifically, Figures 12A and 12B show exemplary embodiment of a channel of the multi-channel read-out integrated circuit 139 configured for read-out of the detector signal, whereas Figures 12C and 12D show exemplary embodiments of a channel of the multi-channel read-out integrated circuit 139 configured for generating the item of information on an electrically measurable quantity required for driving the light source 114.

As can be seen in Figure 12A, the exemplary channel of the multi-channel read-out integrated circuit 139 comprises the buffered direct injection circuit 141 . By applying a bias voltage V^sto the BDI circuit 141 , a voltage applied to the detector 128 may be kept constant. A current due to the applied voltage may be skimmed by means of current skimming to remove any offset in the signal. Thus, as shown in Figure 12A, the ROIC 139, specifically the multi-channel read-out ap- plication-specific integrated circuit 142, may comprise at least one skimming circuit 248 configured for current skimming of the current at the detector 128. Any change in the detector resistance due to the illumination may lead to an increased current flow, which may be digitalized by an analog to digital converter (ADC) 250 with a comparatively high time and voltage resolution.

Additionally, as shown in Figure 12B, the skimming circuit 248 may comprise at least one programmable current sink 252 comprising a plurality of transistors (not shown in the Figures). The transistors may be of the same size and may be build-up in parallel or of doubling size build-up in series.

As outlined above, Figure 12C shows an exemplary channel of the multi-channel read-out integrated circuit 139 configured for generating the item of information on an electrically measurable quantity required for driving the light source 114. In this example, the light source 114 may comprise the LED 118. The spectrometer device 110, as shown in Figure 12C, may further comprise at least one resistor 254 electrically connecting the light source 114 with the multi-channel read-out integrated circuit 139. Specifically, in this case, the resistor 254 may electrically connecting an anode of the LED 118 with the ROIC 139. Further, in this example, the resistor 254 may have a resistance of R = 2 .

Additionally, as can be seen in Figure 12D, the spectrometer device 110 may comprise at least one shunt resistor 256. In this example, as shown in Figure 12D, the spectrometer device 110 may comprise at least two resistors 254. Each side of the shunt resistor 256 may be electrically connected via one of the resistors 254 to the multi-channel read-out integrated circuit 139. Thus, both a voltage drop at the shunt resistor 256 and a current through the light source 114 may be determinable. The shunt resistor 256, as an example, may have a resistance of R = in, whereas the resistors 254 connecting the shunt resistor 256 to the ROIC 139 may have an resistance of of R = lAffl. In the examples of Figures 12C and 12D, the resistors 254 and/or the shunt resistor 256 may have a temperature coefficient smaller than 1000 ppm/K, specifically smaller than 100 ppm/K, more specifically smaller than 50 ppm/K, more specifically smaller than 10 ppm/K.

Figure 13 shows a diagram with a current-voltage characteristic of the light-emitting diode (LED) 118. Specifically, the diagram shows the current 258 at the LED 118 as a function of voltage 260. As can be seen in Figure 13, if the current 258 at the LED 118 may be regulated to a constant current I_set, specifically such that the LED 118 stays on a constant level power output, the change in voltage is minimum in the chosen current range. For example, the current 258 at the LED 118 may be chosen such that the LED 118 may have a forward voltage of 2.7 V to 2.9 V depending on a temperature. In the ROIC 139, the BDI's 141 input voltage may be set to a steady 2.6 V. Thus, by connecting the resistor 254, specifically a resistor with a low temperature coefficient as outlined above, between the anode of the LED 118 and the input of the ROIC 139, it may be possible to analyze the item of information on an electrically measurable quantity required for driving the light source 114 in the region of interest of about 0.1 V - 0.3 V with high precision. However, other input voltages may also be feasible for other light sources 114. Thus, the BDI 141 may serve as an offset removal circuit.

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 array of photosensitive elements evaluation unit driving unit multi-channel read-out integrated circuit current source buffered direct injection (BDI) circuit multi-channel read-out application-specific integrated circuit (ASIC) data processing devices preprocessing devices data storage devices filter element optical component wavelength-selective element substrate ceramic substrate contact pad converter body side coat hardware components software components temperature of the LED temperature of the luminescent material temperature of the detector target signal S_t electronic detector signal S_pXii readout electronics software 1 software 2 first processing step fast Fourier transformation pixel signal S_px second processing step signal S_px, _Corr spectrum peak power spectral density in microwatt per nanometer y-axis wavelength in nm x-axis

1643nm

1750nm

1802nm

1950nm emission power change normalized to 25°C (given in percent) temperature in °C measuring points forward voltage in Volt signal in number of counts decay constant T_d in ms growth constant t_g in ms normalized light output forward current in Ampere fitted curves electrically driving the light source illuminating the object generating the detector signal generating the item of information on an electrically measurable quantity required for driving the light source evaluating the detector signal skimming circuit analog to digital converter programmable current sink resistor shunt resistor current voltage

Claims

1 . A spectrometer device (110) for obtaining spectroscopic information on at least one object (112), the spectrometer device (110) comprising: i. at least one light source (114) for generating illumination light (116) for illuminating the object (112), wherein the light source (114) comprises at least one electrically driven light source; ii. at least one detector (128) for detecting detection light (130) from the object (112) and generating at least one detector signal; ill. at least one driving unit (138) for electrically driving the light source (114); iv. at least one multi-channel read-out integrated circuit (139), wherein each channel of the multi-channel read-out integrated circuit (139) comprises at least one buffered direct injection (BDI) circuit (141), wherein the BDI circuit (141) is configured for read-out of the detector signal, wherein the BDI circuit (141 ) is configured for generating at least one item of information on an electrically measurable quantity required for driving the light source (114), wherein the multi-channel read-out integrated circuit (139) comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) (142) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source (114), wherein the item of information on the electrically measurable quantity required for driving the light source (114) comprises at least one item of information selected from the group consisting of: a forward voltage at the light source (114); a voltage drop at the light source (114); a current at the light source (114); an electrical power input at the light source (114); a resistance of the light source (114); an impedance of the light source (114); and v. at least one evaluation unit (136) for evaluating at least one detector signal generated by the detector (128) and for deriving the spectroscopic information on the object (112) from the detector signal, wherein the evaluation unit (136) is configured for taking into consideration the item of information on the electrically measurable quantity required for driving the light source (114) when deriving the spectroscopic information from the detector signal, wherein the evaluation unit (136) is configured for determining at least one correction from the item of information on the at least one electrically measureable quantity, wherein the evaluation unit (136) is configured for correcting the at least one detector signal, by using the correction.

2. The spectrometer device (110) according to the preceding claim, wherein the light source (114) is configured for emitting light in a spectral range at least partially comprising an infrared spectral range.

3. The spectrometer device (110) according to any one of the preceding claims, wherein the light source (114) comprises at least one light source selected from the group consisting of: an incandescent lamp; a light-emitting diode (LED) (118); a light-emitting diode (LED) (118) and at least one luminescent material (120) for light-conversion of primary light generated by the light-emitting diode (118); a laser, a solid-state laser, a gas laser, a quantum cascade laser; a plasma light source; a low pressure discharge lamp; a high pressure discharge lamp; an electrical light source.

4. The spectrometer device (110) according to any one of the preceding claims, wherein the multi-channel read-out application-specific integrated circuit (ASIC) (142) comprises at least one skimming circuit (248) configured for current skimming of a current at the detector (128).

5. The spectrometer device (110) according to any one of the preceding claims, further comprising at least one resistor (254) electrically connecting the light source (114) with the multi-channel read-out integrated circuit (139).

6. The spectrometer device (110) according to any one of the preceding claims, further comprising at least two resistors (254) electrically connecting the light source (114) with the multi-channel read-out integrated circuit (139) and at least one shunt resistor (256), wherein each side of the shunt resistor (256) is electrically connected via at least one of the resistors (254) to the multi-channel read-out integrated circuit (139).

7. The spectrometer device (110) according to any one of the two preceding claims, wherein the resistor (254) and/or the shunt resistor (256) have a temperature coefficient smaller than 1000 ppm/K.

8. The spectrometer device (110) according to any one of the preceding claims, wherein the detector (128) comprises a plurality of photosensitive element, wherein each of the photosensitive elements is configured for generating at least one detector signal, wherein the evaluation unit (136) is configured for individually considering the item of information on the electrically measurable quantity required for driving the light source (114) for each of the detector signals of the photosensitive elements and for combining the detector signals for deriving the spectroscopic information.

9. The spectrometer device (110) according to the preceding claim, wherein the spectrometer device (110) is configured such that the photosensitive elements are sensitive to differing spectral ranges of the light from the object (112), wherein the spectrometer device

(110) comprises at least one wavelength-selective element (152) disposed in a beam path of the detection light (130), wherein the wavelength-selective element (152) is configured such that each of the photosensitive elements is exposed to an individual spectral range of the detection light (130) from the object (112).

10. A method of obtaining spectroscopic information on at least one object (112) by using a spectrometer device (110), the method comprising: a. electrically driving at least one light source (114) by using at least one driving unit (138), wherein the light source (114) comprises at least one electrically driven light source; b. illuminating the object (112) with illumination light (116) generated by the light source (114); c. generating at least one detector signal by detecting detection light (130) from the object (112) using at least one detector (128); d. generating at least one item of information on an electrically measurable quantity required for driving the light source (114) by using at least one multi-channel read-out integrated circuit (139), wherein each channel of the multi-channel read-out integrated circuit (139) comprises at least one buffered direct injection (BDI) circuit (141), wherein the BDI circuit (141) is configured for read-out of the detector signal, wherein the BDI circuit (141 ) is configured for generating the at least one item of information on an electrically measurable quantity required for driving the light source (114), wherein the multi-channel read-out integrated circuit (139) comprises at least one multi-channel read-out application-specific integrated circuit (ASIC) (142) configured for synchronous sampling the detector signal and the item of information on the electrically measurable quantity required for driving the light source (114), wherein the item of information on the electrically measurable quantity required for driving the light source (114) comprises at least one item of information selected from the group consisting of: a forward voltage at the light source (114); a voltage drop at the light source (114); a current at the light source (114); an electrical power input at the light source (114); a resistance of the light source (114); an impedance of the light source (114); and e. evaluating the at least one detector signal generated by the detector (128) by using at least one evaluation unit (136) and deriving the spectroscopic information on the object (112) from the detector signal taking into consideration the item of information on the electrically measurable quantity required for driving the light source (114); wherein, in step e., at least one correction is determined from the item of information on the electrically measurable quantity required for driving the light source (114), wherein, further, the at least one detector signal is corrected, by using the correction.

11 . The method according to the preceding claim, wherein the correction comprises at least one temperature correction, the temperature correction being at least partially dependent on the item of information on the electrically measurable quantity required for driving the light source (114).

12. The method according to any one of the two preceding claims, wherein the corrected detector signal is used for deriving the spectroscopic information.

13. A computer program comprising instructions which, when the program is executed by a 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.

14. A computer-readable storage medium comprising instructions which, when the instruc- tions are executed by a 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.