Background-based photodetector drift correction

Abstract

The invention relates to a method for determining at least one correction function for compensating for a change in responsivity of at least one photodetector (120). The photodetector (120) comprises at least one photosensitive area (122) and at least one readout electronics unit (124) for reading out the photosensitive area (122). The method comprises the following steps: a) determining at least one reference signal of the photodetector (120) wherein the photosensitive region (122) is illuminated by light radiation (112) provided by at least one reference (156) for determining the reference signal; b) determining at least one background signal level of the photodetector (120); c) determining the correction function by using at least one evaluation unit (132), where determining the correction function comprises determining a change in the background signal level and evaluating a relationship of the change in the background signal level with the reference signal. Further, a method for determining at least one item of information about at least one measurement object (114), a photodetector (120) and a spectrometer (110) are proposed.

Description

Technical Field

[0001] The invention relates to a method for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector, a method for determining at least one item of information about a measurement object using at least one photodetector, a photodetector and a spectrometer. Such a method and an apparatus can generally be used for research or monitoring purposes, in particular in the infrared (IR) spectral region, in particular in the near infrared (NIR) spectral region, and for detecting heat, flames, fire or smoke. However, other kinds of applications are also possible. Background Art

[0002] Optical spectroscopy methods, specifically in the near-infrared and mid-infrared spectral ranges, allow insights into the molecular structure of an object by observing the vibrations of molecular bonds. While mid-infrared light can be used to excite fundamental vibrational modes with high finesse and absorption intensity, the near-infrared spectral range enables the observation of higher modes (harmonics) and combination bands at lower absorption intensities. These advantages can make it possible to probe bulk objects and obtain information about molecular composition by using near-infrared spectroscopy. Therefore, NIR spectroscopy can be widely used in life and natural sciences, medicine, material science, agriculture, food or pharmaceutical industries, for example, for blood glucose measurement, pulse oximetry, fat content, material classification, product fraud identification and many other applications.

[0003] However, in contrast to spectrometers operating in the visible, it is generally quite difficult to provide analytical equipment for the NIR wavelength range: silicon-based photodetectors are generally not suitable for light with wavelengths above 1.1 μm due to the band structure. However, indium, germanium or lead salts or thermopiles can be applied. Typically, NIR detectors in laboratory spectrometers as well as in benchtop spectrometers are usually thermoelectrically cooled using multiple stages, in particular in order to achieve low temperatures, high detectivity and stability against temperature drifts. However, thermoelectric cooling typically increases technical complexity, size and power consumption, which hinders the widespread application of NIR spectroscopy, for example for point-of-care analysis or in consumer devices.

[0004] Therefore, it is desirable to operate an IR spectrometer without cooling, wherein the detector material preferably works over a wide range of operating conditions and ambient temperatures. Therefore, when comparing the measurement results with a reference signal or when repeating measurements, it is necessary to compensate for the drift of the detector material caused by temperature in order to reduce the measurement noise.

[0005] Photoresistors can exhibit temperature dependence. For example, the dark resistance, responsivity, and detectivity of photoconductive detectors, such as those made of, for example, PbS, PbSe, exhibit strong temperature dependence. Systematic drift may occur due to changes in the electronics. For example, typically, a bias voltage is applied to the photoresistor to generate dark current and signal current, and changes in the temperature of the electronics may introduce systematic drift in the measured detector signal. Both detector changes and electronics changes may occur simultaneously.

[0006] Therefore, small changes in the detector temperature may lead to large errors in the obtained light signal. Typically, a temperature sensor on the detector substrate is used to monitor the detector temperature. In order to achieve the most accurate results for multi-pixel devices, even several temperature sensors are needed. Typically, thermoelectric coolers (TECs) and TEC controllers are used to stabilize the temperature of the detector to mitigate these temperature effects. The temperature of the sensor is used to control the current through the TEC in a way that keeps the temperature of the sensor as constant as possible (a few mK). Therefore, the temperature of the detector is also estimated to be constant. Significant changes in the responsivity due to changes in the detector temperature are not expected and are not taken into account.

[0007] Devices and methods are known, for example from JP H01110225A, CN 2359677 Y, US 6852966B1, US20110255075A1, CN 109307550A, JP S61213650A, CN 103076087A, DE 102009026951A1, which apply temperature correction based on a temperature sensor or on a second optical detector that is the same as the main detector.

[0008] WO 2021 / 069544 A1 describes a device comprising: - at least one photoconductor array, wherein each photoconductor is configured to exhibit a resistance related to illumination of its photosensitive area, wherein at least one photoconductor in the array is designed to be a characterizing photoconductor; - at least one bias voltage source, wherein the bias voltage source is configured to apply at least one AC bias voltage to the characterizing photoconductor or to apply at least one direct current (DC) bias voltage to the characterizing photoconductor; - at least one photoconductor readout circuit, wherein the photoconductor readout circuit is configured to determine a response voltage of the characterizing photoconductor generated in response to the bias voltage, wherein the response voltage is proportional to a variable characterizing the photoconductor array, wherein the photoconductor readout circuit is configured to determine the response voltage of the characterizing photoconductor during operation of the photoconductor array.

[0009] US2018 / 073923 A1 describes an optical measurement method using a detector having detection sensitivity to at least the near-infrared region. The optical measurement method includes: obtaining an output value by measuring a light sample with the detector at any exposure time; and correcting the output value with a correction amount corresponding to the output value when the exposure time for obtaining the output value is within a second range. The correction amount includes a coefficient multiplied by the square of the exposure time, the coefficient indicating the degree of deviation of the output linearity obtained when the light sample is measured with the detector at an exposure time within the second range from the output linearity obtained when the light sample is measured with the detector at an exposure time within the first range.

[0010] US 4,773,761 A describes a photoelectric colorimeter, which includes a photoelectric conversion section, which includes: an optical filter and a photoelectric sensor, the optical filter is used to analyze the light from the test piece and the reference of the sample to calibrate the sample into primary color elements, and the photoelectric sensor is used to convert each of the primary color elements into an electrical signal; and a data processing section, the data processing section includes: a calibration constant calculation device, the calibration constant calculation device is used to calculate the calibration constant of each of a plurality of reference calibration samples based on the calibration point of each of the reference calibration samples and the information input from the photoelectric conversion section; a chromaticity point calculation device, the chromaticity point calculation device is used to calculate the chromaticity point of the test piece and the chromaticity point of each reference calibration sample; a memory device, the memory device is used to store the calibration constant and the calibration point of each of the reference calibration samples; an estimation device, the estimation device is used to estimate a new calibration constant suitable for the chromaticity point of the test piece by interpolation between the corresponding calibration constants of the reference calibration samples using the positional relationship between the chromaticity point of the calibration point and the chromaticity point of the test piece as a parameter; and a correction device, the correction device is used to correct the measurement value of the test piece by the new calibration constant.

[0011] M. Krupinski et al., “Test stand for non-uniformity correction of microbolometer focal plane arrays used in thermal cameras,” SPIE SMART STRUCTURES AND MATERIALS + NONDESTRUCTIVE EVALUATION AND HEALTH MONITORING, 2005, San Diego, California, USA, Vol. 8896, p. 889611, XP093006817, US ISSN: 0277-786X, DOI: 10.1117 / 12.2028633 ISBN: 978-1-5106-4548-6, relates to the correction of the non-uniform response of a particular detector (pixel) to infrared radiation of the same incident power.

[0012] US2021 / 025758 A1 describes a system for non-invasively probing an in vivo sample to measure an analyte, the system comprising: a pulse sensor connected to the in vivo sample to detect the blood pulse of the sample and generate a corresponding pulse signal; a laser generator for generating laser radiation having a wavelength, power and diameter, the laser radiation being directed toward the sample to induce a Raman signal; a laser controller suitable for activating the laser generator; a spectrometer for receiving the Raman signal and generating analyte spectral data; and a computing device connected to the pulse sensor, the laser controller and the spectrometer, the computing device being suitable for associating spectral data with the pulse signal based on timing data received from the laser controller so as to separate spectral components of the analyte from the blood of the sample from spectral components of the analyte generated by non-blood components of the sample.

[0013] Despite the advantages implied by the above-described apparatus and methods, there is still a need for improvement. In particular, there is a need for improved compensation for both detector variations and electronic component variations.

[0014] Problem to be solved

[0015] The problem addressed by the present invention is therefore to provide methods and devices for compensating for responsivity variations of at least one photodetector, which methods and devices at least substantially avoid the disadvantages of known methods and devices of this type. In particular, it is desirable to provide methods and devices that ensure improved compensation of both detector variations and electronic component variations in a simple and safe manner, in particular without requiring the installation of additional components. Summary of the invention

[0016] This problem is solved by the invention having the features of the independent claims. Advantageous embodiments which can be realized individually or in any arbitrary combination are listed in the dependent claims as well as in the entire description.

[0017] In a first aspect of the invention, a method for determining at least one correction function for compensating for responsivity variations of at least one photodetector is disclosed. The photodetector comprises at least one photosensitive area and at least one readout electronics unit for reading out the photosensitive area. The method comprises the following steps:

[0018] a) determining at least one reference signal of the photodetector, wherein the photosensitive area is illuminated by optical radiation provided by at least one reference for determining the reference signal;

[0019] b) determining at least one background signal level of the photodetector;

[0020] c) determining the correction function by using at least one evaluation unit, wherein determining the correction function comprises determining a change in a background signal level and evaluating the change in the background signal level in relation to the reference signal.

[0021] The method steps may be performed in the order indicated. However, it should be noted that a different order is also possible. The method may include additional method steps not listed. Further, one or more of the method steps may be performed once or repeatedly. Further, two or more of the method steps may be performed simultaneously or in a time-overlapping manner. The method may include repeating steps a) to c) at a predefined time or continuously.

[0022] The method may be at least partially implemented by a computer. As used herein, the term "computer-implemented method" is a broad term and will be given its common and conventional meaning for those of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a method involving at least one computer and / or at least one computer network. The computer and / or computer network may include at least one processor that may be configured to perform at least one method step of the method according to the present invention. Specifically, each of these method steps is performed by a computer and / or a computer network. The method may be performed fully automatically, specifically without user interaction.

[0023] As used herein, the term "photodetector" is a broad term and will be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, an optical detector or sensor configured to detect optical radiation, such as for detecting illumination and / or a light spot generated by at least one light beam. The photodetector may include at least one substrate. A single photodetector may be a substrate having at least one single photosensitive region that generates a physical response to illumination of a given wavelength range.

[0024] The photodetector may include at least one photosensitive area, also denoted as a photosensitive region. The photodetector may include a plurality of photosensitive areas, which may be arranged in at least one of an array or a matrix. As used herein, the term "photosensitive area" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a unit of a photodetector configured for illumination, or in other words for receiving light radiation, and for generating at least one signal (such as an electronic signal) in response to the illumination. The photosensitive area may be located on the surface of the photodetector. The photosensitive area may specifically be a single, enclosed, uniform photosensitive area. However, other options may also be feasible. The photosensitive area may also be referred to as a pixel.

[0025] Illumination can be provided by at least one measurement object. The provision can include at least one of reflection, transmission and emission. Specifically, before interacting with the measurement object, illumination can be emitted, for example, by at least one radiation source. As used herein, the term "radiation source" is a broad term and will be given its ordinary and conventional meaning for ordinary technicians in the field and is not limited to special or custom meanings. The term can specifically refer to, but is not limited to, a device configured to emit optical radiation. The radiation source can be configured to emit optical radiation, such as optical radiation in the form of a beam, toward the measurement object. The radiation source can be configured to emit optical radiation isotropically (e.g., uniformly in all spatial directions), wherein only a portion of the emitted optical radiation can illuminate the measurement object. The radiation source can include at least one of a semiconductor-based radiation source or a thermal radiator. At least one semiconductor-based radiation source can be selected from at least one of a light emitting diode (LED) or a laser (specifically a laser diode). The LED can include at least one fluorescent and / or phosphorescent material. The thermal radiator can include at least one of an incandescent lamp, a black body emitter, and a micro-electromechanical system (MEMS) emitter. The radiation source can be a modulated radiation source. Other types of radiation sources may also be possible.

[0026] As used herein, the term "illumination" is a broad term and will be given its ordinary and conventional meaning for ordinary technicians in the field and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, light radiation, specifically light radiation in at least one spectral range of the visible light spectrum, the ultraviolet spectrum, or the infrared spectrum. The term "ultraviolet light" generally refers to electromagnetic radiation with a wavelength of 1nm to 380nm, preferably 100nm to 380nm. Further, the term "visible light" generally refers to a wavelength of 380nm to 760nm. Further, the term "infrared" ("abbreviated as IR") generally refers to a wavelength of 760nm to 1000μm, wherein a wavelength of 760nm to 3μm is generally referred to as "near infrared" (abbreviated as "NIR"). Preferably, the illumination used for the typical purpose of the present invention is IR radiation, more preferably NIR radiation, especially radiation with a wavelength of 760nm to 3μm, preferably 1μm to 3μm. The illumination can specifically be light radiation that illuminates a photodetector or more specifically a photosensitive area. The term “illumination” may also be referred to herein as “optical radiation” or “light.” The photodetector may be configured to detect optical radiation within a wavelength of 300 nm to 3000 nm, specifically 500 nm to 2500 nm, more specifically 1400 nm to 2000 nm.

[0027] The illumination can be modulated, for example, by using a modulated radiation source. The radiation source can be a modulated radiation source. As used herein, the term "modulation" (including any grammatical variations thereof) is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, a process of changing, specifically periodically changing at least one characteristic of the optical radiation, specifically one or both of the intensity or phase of the optical radiation. As the technician will know, intensity is also related to the amplitude of the optical radiation. Modulation can be a full modulation from a maximum value to zero, or it can be a partial modulation from a maximum value to an intermediate value greater than zero. Modulation can include the use of a modulating element. The modulating element can be configured to, for example, mechanically modulate the optical radiation (for example, by using a rotating chopper wheel) and / or for electronically modulating the optical radiation (for example, by using an electro-optic effect and / or an acousto-optic effect, for example, by using a Pockels cell and / or a Kerr cell). Other options are also feasible.

[0028] The photosensitive region may include at least one photoconductive material. The photoconductive material may be selected from at least one of PbS, PbSe, Ge, InGaAs, InSb, or HgCdTe. Other options such as photodiodes or thermopiles may also be possible. The photodetector may be configured to generate at least one signal such as a photocurrent, specifically generating at least one measurement signal in response to illumination of the photosensitive region.

[0029] The photodetector includes at least one readout electronics unit for reading out the photosensitive area. As used herein, the term "readout" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, the 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 the at least one photodetector, or more specifically a photosensitive area). Readout may include a separate readout of a device (such as a photosensitive area). Additionally or alternatively, readout may include a readout of a group of devices (such as a group of photosensitive areas).

[0030] As used herein, the term "readout electronics unit" is a broad term and is given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to, but is not limited to, an electronics unit configured to quantify and / or process at least one physical property and / or a change in at least one physical property detected by a photodetector or more specifically a photosensitive area. The readout electronics unit may include at least one of the following: an operational amplifier; an analog-to-digital converter; a voltage divider; a current divider, an ASIC, specifically for subtracting a constant current to generate a signal current.

[0031] For example, the photodetector may include a bias voltage source. As used herein, the term "bias voltage source" is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, at least one voltage source configured to generate a bias voltage. The bias voltage source may be configured to apply at least one (e.g., constant) bias voltage V to the photodetector, specifically to a photosensitive region (which may be considered a resistor in this context). 偏置 The bias voltage V can be applied to the photosensitive area by using a bias voltage source 偏置 To generate dark signals, especially dark current I D . Dark current I D can flow through the photodetector, where I D =V 偏置 / R D , where V偏置 is the bias voltage, and R D is the dark resistance. The readout electronics unit can be configured to read the dark current I D Subtract the constant current I q , which gives the signal current I S =I D –I q . Signal current I S It can be amplified by the front-end electronics (AMP), and then an analog-to-digital converter (ADC) can be used to generate a digital signal S. 偏置 Changes in may cause changes in responsivity, which can be corrected by using the compensation method according to the present invention.

[0032] As used herein, the term "compensation" (including any grammatical variations thereof) is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, the elimination or correction of a physical effect, specifically a disturbing influence or interference or disturbance. Compensation may be or may include a measure for a disturbance. Specifically, compensation may be temperature compensation, wherein the temperature or more specifically a temperature change may be, for example, a disturbance to a detector. As an example, the responsiveness of a photodetector may be temperature dependent. Thus, changes in the ambient temperature of the photosensitive area may result in additional changes in the detector signal that are not responsive to illumination of the photodetector. In other words, the detector signal may be subject to temperature drift.

[0033] The method may comprise compensating for changes in the responsivity of the photosensitive area caused by a physical quantity influencing the resistance, in particular the dark resistance, of the photosensitive area. The method may comprise compensating for changes in the responsivity of the photosensitive area caused by at least one of: a change in the temperature of the photosensitive area; a change in the illumination of the photosensitive area, in particular due to at least one background radiation; a change in the temperature of the evaluation unit or at least a part thereof; a change in at least one physical quantity, in particular the temperature, of the photodetector or at least a part thereof, in particular at least one optional further electronic component of the photodetector, as described above or as described in more detail below.

[0034] As used herein, the term "responsivity" is a broad term and will be given its ordinary and conventional meaning for those of ordinary skill in the art and will not be limited to a special or custom meaning. The term may specifically refer to, but is not limited to, the relationship between at least one input and at least one output of a photodetector. Responsivity can be the relationship between an optical input and an electrical output. Responsivity can measure the electrical output (e.g., photocurrent or resistance) for each optical input (e.g., light intensity or irradiance). Responsivity may also be referred to as photosensitivity. As used herein, the term "responsivity variation" is a broad term and will be given its ordinary and conventional meaning for those of ordinary skill in the art and will not be limited to a special or custom meaning. The term may specifically refer to, but is not limited to, any deviation in responsiveness, such as any deviation in responsiveness determined relative to a predefined value and / or at different points in time.

[0035] In step a), at least one reference signal of the photodetector is determined. The photosensitive area is illuminated by optical radiation provided by at least one reference for determining the reference signal. In step b), at least one background signal level of the photodetector is determined.

[0036] As used herein, the term "signal" is a broad term and will be given its common and conventional meaning for those of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, an observable change in at least one physical quantity. A signal may be or include a symbol or function that conveys information about the at least one physical quantity. A signal may specifically be or include at least one of an electronic signal, an optical signal, or a photoelectric signal. A signal may be a variable signal, specifically a signal that is variable over time. A signal may be or include at least one of: a variable voltage, a variable current, a variable charge, a variable resistance, or generally a variable electromagnetic wave. A variable electromagnetic wave may include at least one of a variable amplitude, a variable frequency, or a variable phase. Additional options are feasible and are generally well known to the technician.

[0037] As used herein, the term "reference" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, at least one arbitrary object. In particular, the reference may have at least one known physical property, in particular at least one optical property. Other embodiments are also feasible. For example, the reference may have unknown physical properties. For example, the reference may be a measurement object, such as a sample to be measured. As an example, when analyzing a measurement object, multiple measurement values ​​may be recorded, wherein at least one measurement value may be used as a reference value.

[0038] As used herein, the term "measurement object" is a broad term and will be given its common and conventional meaning for those of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, any body selected from a living body and an inanimate body. The measurement object may specifically include at least one material that is subjected to research. The measurement object may generally refer to an object to be measured (e.g., for which a spectrum is to be recorded), wherein the measurement object may have any characteristic in principle (e.g., any optical characteristic or any shape). The measurement object may include at least one solid sample. However, other measurement objects such as fluids may also be feasible.

[0039] As used herein, the term "reference signal" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a signal generated by a photodetector in response to illumination by light radiation provided by a reference. In particular, a reference signal may be generated by a photosensitive area in response to illumination. A reference signal may be or include at least one signal generated at a single point in time. A reference signal may be or include at least one signal generated within a time period. A reference signal may be or include at least one pre-processed signal, such as a filtered or smoothed or amplified signal. A reference signal may be or include at least one of an analog signal or a digital signal.

[0040] Step a) may comprise determining a plurality of reference signals. For example, the reference signal may be determined for: different conditions of the photodetector, in particular one or more of different temperatures of the photosensitive area; different illumination of the photosensitive area; different temperatures of the evaluation unit or at least parts thereof; different physical quantities of the photodetector or at least parts thereof, in particular different physical quantities of at least one optional further electronic component of the photodetector described below, i.e. different bias voltages. The reference signal may be determined at different times. For example, the reference signal may be determined for different predefined temperatures.

[0041] The reference signal may be measured online using frequency multiplexing during sample measurement and / or in the absence of sample measurement by measuring the reference signal for at least one extended period of time. For example, different frequencies may be used for sample measurement and measurement of the reference signal. For example, the optical radiation in step a) may be modulated. Additionally or alternatively, the reference signal may be measured before or after the sample measurement.

[0042] As used herein, the term "background signal" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a signal generated by a photodetector that is independent of illumination. For example, in order to determine the background signal, the photosensitive area may be covered by at least one opaque cover and / or not illuminated. As an example, when modulated light radiation is used, the photosensitive area may not be illuminated at least for a predefined time interval. The modulation may be a full modulation down to zero intensity, so that the photosensitive area may not be illuminated at a minimum value of the intensity of the modulated light radiation. For example, in the absence of illumination, the photosensitive area may be configured to generate a background signal. The background signal may be a signal generated by the photosensitive area, wherein illumination of the photosensitive area is suppressed when the background signal is generated. The background signal may depend on at least one intrinsic property of the photosensitive area, in particular a material property of at least one semiconductor comprised by the photosensitive area. The background signal may specifically depend on the temperature of the photosensitive area. The background signal may include a dark signal, in particular a dark current. The dark current may be thermally induced by the spontaneous formation of free charge carriers in the semiconductor of the photosensitive area.

[0043] As used herein, the term "background signal level" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, the average value of the minimum value of the background signal. In step a), the light radiation may be modulated. The background signal level may be determined by using the time and phase of the minimum value of the modulated light radiation. Determining the background signal level may include extrapolating a dark signal and / or modeling the dark signal. For example, the dark signal may be extracted only from the dark phase. Extrapolation may include, for example, extrapolating to a time when the background signal is not determined during illumination of the photosensitive area, for example, during determination of a reference signal and / or during sample measurement. Modeling the measured dark signal may include, for example, fitting the measured dark signal using a predefined fitting function to the identified minimum value. For example, the predefined fitting function may be a linear function.

[0044] The method may comprise measuring a reference signal and a background signal, in particular both, under at least two different conditions of the photodetector. The condition of the photodetector may be set by setting and / or adjusting the value of at least one influencing variable. The influencing variable may be at least one variable influencing the dark resistance of the photosensitive area. The influencing variable may be at least one variable selected from the group consisting of: the temperature of the photosensitive area; the illumination of the photosensitive area; the temperature of the evaluation unit or at least a part thereof; at least one physical quantity of the photodetector or at least a part thereof, in particular at least one physical quantity of at least one optional further electronic component of the photodetector described below, i.e. a bias voltage.

[0045] The background signal level and the reference signal can be measured synchronously in time. As used herein, the term "synchronous in time" is a broad term and will be given its ordinary and conventional meaning for ordinary technicians in the field and is not limited to special or custom meanings. The term can specifically refer to but is not limited to the fact that the determination of the reference signal and the dark signal is performed in the same measurement and / or at the same time. Not only can the time information of the signal measured synchronously in time be used, but it can also be measured synchronously in time by using phase information. The signal S measured synchronously in time can be described as a complex polynomial S (phase, t) = P1 (phase) + P2 (t), where P1 and P2 are polynomials as functions of phase and time, respectively. P1 can be selected so that it reaches 0 at the phase of the minimum signal; then, P2 describes the dark signal over time so that the dark signal can be modeled. The method may include considering the complete synchronous measurement signal or only considering a portion of the synchronous measurement signal. For example, a portion of the synchronous measurement signal that is away from the minimum phase by about a predefined limit (e.g., about ± 1ms) can be used to model the dark signal. The optimization of the problem and the analytical description for dark signal modeling may depend on one or more of the modulation form, frequency and signal decay time and the light source used. Measuring synchronously in time may allow online calibration, i.e. calibration during operation of the photodetector. Measuring synchronously in time may allow preventing the need for additional calibration time and thus improving measurement efficiency.

[0046] For example, determining the background signal level in step b) may include determining the dark signal from the dark phase during determination of the reference signal. As used herein, the term "dark phase" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, at least one time range in which the photosensitive area is covered by at least one opaque cover and / or is not illuminated. For example, the dark signal may be extracted from the dark phase and may be extrapolated for the phase at which light is incident on the photosensitive area. However, other embodiments are also feasible. For example, the background signal level and the reference signal may be measured at different times. For example, step b) may include determining the dark signal before and / or during and / or after determining the reference signal.

[0047] The method may use the dark current together with a reference signal that is not necessarily time synchronized to correct for responsivity variations. As outlined above, the determination of the dark signal may be performed during the dark phase so that no additional measurements are required before and / or after the sample measurement. This may allow even small scale variations (i.e., time scales below the measurement time) to be tracked. In addition, the method may include determining the dark signal before and / or between and / or after the modulation measurement so that the dark signal is determined in true darkness throughout the measurement period. The determination of the coefficients of the correction function may be performed by actively tracking the reference signal and the dark signal in an online manner. This may be achieved by frequency multiplexing or by tracking the reference over an extended period of time without obtaining a sample measurement.

[0048] Step c) comprises determining a correction function by using at least one evaluation unit. Determining the correction function comprises determining a change in a background signal level and evaluating the change in the background signal level in relation to a reference signal.

[0049] As used herein, the term "evaluation" (including any grammatical variations thereof) is a broad term and is to be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, analyzing or interpreting data, specifically for determining at least one item of qualitative or quantitative information. Evaluation may include processing data, such as by processing data using at least one relationship, specifically at least one function having at least one of a variable or a predetermined parameter.

[0050] As used herein, the term "evaluation unit" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a device configured to analyze or interpret data, specifically for determining at least one qualitative or quantitative information. The information may be obtained specifically by evaluating at least one detector signal generated by at least one photodetector. The evaluation unit may be or may include at least one of an integrated circuit (particularly an application specific integrated circuit (ASIC)) or a data processing device, in particular a digital signal processor (DSP), a field programmable gate array (FPGA), a microcontroller, a microcomputer, a computer or an electronic communication unit (particularly a smart phone or a tablet). Additional components may be feasible, in particular at least one preprocessing device or a data acquisition device. Further, the evaluation unit may include at least one interface, in particular at least one of a wireless interface or a wired interface. Further, the evaluation unit may be designed to completely or partially control or drive another device, such as at least one photodetector. Information such as determined by the evaluation unit may be provided to at least one of another device or a user in at least one of an electronic, visual, auditory or tactile manner, particularly preferably. Further, the information can be stored in at least one data storage unit, in particular in an internal data storage unit such as comprised by the photodetector or at least the spectrometer, in particular by the at least one evaluation unit, or in a separate storage unit to which the information can be transmitted via at least one interface. The at least one electronic communication unit can include the separate storage unit. The storage unit can be particularly configured to store at least one electronic table, such as at least one look-up table.

[0051] The evaluation unit can preferably be configured to execute at least one computer program, in particular at least one computer program that executes or supports the steps of the method according to the invention. For this purpose, the evaluation unit can in particular comprise at least one data processing device, in particular at least one of an electronic data processing device or an optical data processing device. The processing device can be designed to determine the correction function.

[0052] At least one photodetector may include an evaluation unit and / or a communication interface. The communication interface may be configured to perform at least one of the following: transmitting data from or to the evaluation unit or transmitting data within the evaluation unit. As used herein, the term "communication interface" is a broad term and will be given its common and conventional meaning for those of ordinary skill in the art and is not limited to a special or custom meaning. Specifically, the term may refer to, but is not limited to, an article or element that forms a boundary configured to transfer information. In particular, a communication interface may be configured to transfer information from a computing device (e.g., a computer), such as to send or output information to, for example, another device. Additionally or alternatively, a communication interface may be configured to transfer information to a computing device, such as to a computer, such as to receive information. The communication interface may specifically provide a means for transferring or exchanging information. In particular, the communication interface may provide a data transfer connection, such as Bluetooth, NFC, inductive coupling, etc. As an example, a communication interface may be or may include at least one port, the at least one port including one or more of a network or Internet port, a USB port, and a disk drive. The communication interface may include at least one web interface.

[0053] At least one evaluation unit may be at least partially cloud-based. As used herein, the term "cloud-based" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, outsourcing at least one evaluation unit or part of the at least one evaluation unit to an at least partially interconnected external device, specifically a computer or computer network with greater computing power and / or data storage capacity. The external devices may be arbitrarily distributed in space. The external devices may change over time, specifically according to demand. The external devices may be interconnected using the Internet. The external devices may each include at least one communication interface.

[0054] As used herein, the term "correction function" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a mathematical function for compensating for changes in the responsivity of a photodetector. The correction function may include at least one coefficient. The correction function may be a function selected from the group consisting of: a linear function; a polynomial function; an exponential function. The correction function may be applied to correct any measurement signal (including sample measurements) at its corresponding dark signal level.

[0055] Determine that this correction function comprises the variation of determining background signal level.The method may comprise retrieving at least one initial background signal level.Retrieving this initial background signal level may comprise measuring and / or using predefined (e.g., storage) values, such as the value retrieved from a lookup table.For example, the initial background level may be the first background level under a first system state (e.g., at a first temperature).Determine that the variation of this background signal level comprises comparing the initial background signal level with the background signal level determined in step b).The initial background signal level may be the background signal level determined as a previous background signal level, for example, this background signal level was determined during a previous measurement and / or this background signal level was determined during a previous execution according to the method of the present invention.

[0056] Determining the correction function includes evaluating the relationship between the change in the background signal level and the reference signal. The change in the background signal level can be determined relative to the reference signal corresponding to the zero point of the dark signal change. The correction function can be determined by fitting the correction function to the relationship between the change in the background signal level and the reference signal, thereby determining the parameters of the correction function. The correction function can be fitted to the relationship between the reference signal and the modeled change in the dark signal. For example, the correction function is a linear function

[0057]

[0058] Among them, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0059] S with D1 ref,1 and S with D2 ref,2 It can be determined at two different system states, such as at different times and / or at different temperatures, etc. These values ​​can be used to determine calibration coefficients (in the case of a linear correction function), and the correction function is fully defined. Thus, advantageously, knowledge of a reference or absolute temperature may not be required.

[0060] For example, the method can be used to compensate for systematic changes in dark resistance. Any change in dark resistance may result in a change in dark current, and thus a change in signal current will be seen. Changes in dark resistance may be caused by changes in detector temperature, but also by background light or any other amount that may affect the resistance of the photodetector itself. In fact, the method according to the present invention can allow a universal correction scheme for all resistance change modes. Further, any signal or current caused by the light signal on the photodetector can be obtained, because these signals or currents also affect the resistance of the detector. The light signal can be modulated to achieve efficient signal processing that distinguishes the signal from the dark signal and noise and system drift. Long-term stability can vary over time, but using a defined reference signal level, online calibration may be feasible by using the method according to the present invention. The background signal level and the reference signal can be determined in a modulated manner and / or by monitoring the dark phase (e.g., before / after the sample measurement) during the sample measurement. The change in responsiveness (photosensitivity) can be determined based on the change in the dark signal / current as monitored by the reference signal (change). In order to obtain a more accurate calibration, repeated calibration measurements can be obtained.

[0061] For example, the method according to the invention can be used to compensate the current I q and / or bias voltage V 偏置 The photodetector may further comprise at least one temperature stabilization device, in particular a thermoelectric cooler, for controlling the temperature of the photodetector or at least a part thereof, in particular a photosensitive area. Such a photodetector may be denoted herein as a "stabilized detector". The dark resistance may be kept stable by means of, for example, a TEC. System drifts may be caused, for example, by changes in environmental conditions, such as changes in the temperature of electronic components other than the photodetector itself. Under conditions of a constant dark resistance, I q or I D Any change in V 偏置 changes) may cause I S The change in and thus the change in the digital signal S. For a photoresistor, the responsivity can be determined by the basic detector characteristics and the applied bias voltage V 偏置 Therefore, V 偏置 A change in φ may result in a change in the responsivity. Therefore, the method according to the invention can also be applied to compensate for such systematic drifts in the electronics when mapping changes in the dark signal.

[0062] As used herein, the term "temperature stabilization device" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, an element or device configured to keep the temperature of another element or device constant or stable or stable. Specifically, at least one temperature stabilization device may be configured to stabilize the temperature of a photodetector. The temperature stabilization device may be configured to maintain the temperature of a component of the photodetector (such as a photosensitive region and / or a readout electronics unit) at a predetermined level. The temperature stabilization device may be configured to stabilize the temperature of a component of the photodetector (such as a photosensitive region and / or a readout electronics unit). The temperature stabilization device may be or include at least one thermoelectric cooler. As used herein, the term "thermoelectric cooler" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, an electrically driven heat pump configured to transfer heat between at least two spatial regions, thereby generating a heat flux between the at least two spatial regions. Specifically, a thermoelectric cooler may be based on the Peltier effect in order to generate a heat flux. For this purpose, the thermoelectric cooler may in particular comprise at least one Peltier element. The direction of the heat flux may depend on the direction of the current applied to the thermoelectric cooler. Depending on the direction of the heat flux, the thermoelectric cooler may be used to cool at least one spatial region by transferring heat to at least one further spatial region, or to heat the spatial region by transferring heat from at least one further spatial region. Other options may also be feasible.

[0063] The present invention relates to a compensation method, in particular for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector. In particular, the present invention proposes a self-referencing of a photodetector, such as a self-referencing of a photosensitive area (e.g. a pixel). The method comprises determining a reference signal and a background signal using the same photosensitive area (e.g. the same pixel). Thus, the signal of the photosensitive area and its background signal are used, thereby generating a self-reference. Such a self-referencing may allow a constant bias voltage to be applied to the photosensitive area.

[0064] In contrast, WO 2021 / 069544 A1 proposes using several photodetectors (i.e. several photosensitive areas) for reference and application of an AC bias voltage.

[0065] In a further aspect of the invention, a method for determining at least one item of information about at least one measurement object using at least one photodetector is disclosed. The photodetector comprises at least one photosensitive area and at least one readout electronics unit for reading out the photosensitive area. The method comprises the following steps:

[0066] i) providing optical radiation by the measurement object and determining at least one measurement signal by using the photodetector;

[0067] ii) correcting the measurement signal by using at least one evaluation unit, by using a correction function, wherein the correction function is determined by using the method according to the invention for determining at least one correction function; and

[0068] iii) determining the information about the measurement object by evaluating the corrected measurement signal using the evaluation unit.

[0069] The method steps may be performed in the order indicated. However, it should be noted that a different order is also possible. The method may include additional method steps that are not listed. Further, one or more of the method steps may be performed once or repeatedly. Further, two or more of the method steps may be performed simultaneously or in a time-overlapping manner.

[0070] As used herein, the term "measurement information" is a broad term and will be given its ordinary and conventional meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, knowledge or evidence that provides a qualitative and / or quantitative description associated with at least one measurement, specifically at least one measurement object. The measurement information may include at least one of a physical property of the measurement object or a chemical composition of at least one measurement object. The physical property may specifically include an optical property, such as at least one absorbance of the measurement object and / or at least one emissivity of the measurement object. The chemical composition may specifically refer to qualitative and / or quantitative information about at least one material included in the measurement object.

[0071] In step i), the optical radiation provided by at least one measurement object may include a wavelength of 300nm to 3000nm, specifically 500nm to 2500nm, more specifically 1400nm to 2000nm. As used herein, the term "providing" (including any grammatical variations thereof) is a broad term and will be given its ordinary and conventional meaning for ordinary technicians in the field and is not limited to special or custom meanings. The term may specifically refer to but is not limited to at least one of the following: reflection of optical radiation, specifically diffuse reflection; diffraction; transmission and emission. The optical radiation provided by the measurement object may indicate at least one of the physical properties of the measurement object (e.g., the optical properties and / or temperature of the measurement object) and the chemical properties of the measurement object (e.g., the chemical composition of the measurement object). As an example, the optical radiation provided by the measurement object may be emitted by at least one measurement object, specifically at least partially emitted toward a photodetector. Further, the optical radiation provided by the at least one measurement object may be reflected, such as diffusely reflected, by the at least one measurement object at least partially toward the at least one photodetector. Further, the optical radiation provided by the at least one measurement object may be transmitted through the at least one measurement object and at least partially directed toward the at least one photodetector. However, the at least one measurement object may also at least partially absorb the optical radiation, which may specifically indicate at least one physical property of the at least one measurement object and / or at least one chemical property of the at least one measurement object, such as the chemical composition of at least one material forming the at least one measurement object.

[0072] Step ii) comprises correcting the measurement signal by using the evaluation unit, by using the correction function. The correction function is determined by using the method according to the invention for determining at least one correction function. For further details about the method for determining at least one item of measurement information, reference may be made to the description of the method for determining at least one correction function as described above or described in more detail below.

[0073] Step iii) determines information about the measurement object by evaluating the corrected measurement signal using the evaluation unit. For example, the correction function is a linear function, where the i-th measurement signal S meas,i The corrected signal S is corrected by the following formula corr,i ,

[0074]

[0075] in

[0076]

[0077] D1 is the initial background signal level, D2 is the background signal level used to determine the correction function, and Dmeas,i is the measurement signal S meas,i The background signal level, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0078] The method for determining at least one measurement information can be at least partially implemented by a computer. With reference to the computer-implemented aspects of the present invention, one or more or even all of the method steps of one or more of the methods of the embodiments disclosed herein can be performed using a computer or a computer network. Therefore, generally, any of the method steps including the provision and / or manipulation of data can be performed using a computer or a computer network. Generally, these method steps can include any method steps, except for method steps that generally require manual work, such as providing samples and / or performing certain aspects of the actual measurement.

[0079] This article further discloses and proposes a computer program, which includes computer executable instructions, which are used to execute one or more methods in the method according to the present invention in one or more embodiments of the embodiments included in this article when the program is executed on a computer or a computer network. Specifically, the computer program can be stored on a computer-readable data carrier and / or a computer-readable storage medium. Therefore, this article further discloses and proposes a non-transient computer-readable medium, which includes instructions that, when executed by one or more processors, cause the one or more processors to perform at least one method in the method according to the present invention. Specifically, one, more than one or even all of the method steps a) to c) and i) to iii) indicated above can be performed and / or implemented by using one or more processors.

[0080] For example, the non-transitory computer readable medium comprises instructions which, when executed by the one or more processors, cause execution of a method for determining at least one correction function for compensating for a change in the responsivity of at least one photodetector. In particular, the one or more processors may provide instructions to the photodetector and / or at least one control unit of the photodetector for implementing and / or executing determination of at least one reference signal and at least one background signal. In addition, the one or more processors (in particular as an evaluation unit) may perform step c), i.e., determining the correction function comprises determining a change in the level of the background signal and evaluating the relationship of the change in the level of the background signal to the reference signal.

[0081] For example, the non-transitory computer readable medium comprises instructions which, when executed by the one or more processors, cause a method for determining at least one item of information about at least one measurement object to be performed. In particular, the one or more processors may provide instructions to the photodetector for implementing and / or performing the measurement. In addition, the one or more processors (in particular as evaluation units) may perform steps ii) and iii), i.e., correcting the measurement signal by using at least one evaluation unit, by using a correction function, wherein the correction function is determined by using a method according to any one of the preceding claims relating to a method for determining at least one correction function, and determining information about the measurement object by using the evaluation unit by evaluating the corrected measurement signal.

[0082] As used herein, the terms "computer-readable data carrier" and "computer-readable storage medium" may specifically refer to a non-transitory data storage device, such as a hardware storage medium on which computer-executable instructions are stored. A computer-readable data carrier or storage medium may specifically be or may include a storage medium such as a random access memory (RAM) and / or a read-only memory (ROM).

[0083] Thus, in particular, one, more than one or even all of the method steps a) to c) and i) to iii) as indicated above may be performed by using a computer or a computer network, preferably by using a computer program.

[0084] This document further discloses and proposes a computer program product with program code means, so that when the program is executed on a computer or a computer network, the method according to the present invention in one or more of the embodiments included in this document is performed. Specifically, the program code means can be stored on a computer-readable data carrier and / or a computer-readable storage medium.

[0085] This document further discloses and proposes a data carrier having a data structure stored thereon, which, after being loaded into a computer or a computer network (such as loaded into a working memory or a main memory of a computer or a computer network), can execute a method according to one or more embodiments of the embodiments disclosed herein.

[0086] This article further discloses and proposes a computer program product having program code means stored on a machine-readable carrier so that when the program is executed on a computer or computer network, a method according to one or more of the embodiments disclosed herein is performed. As used herein, a computer program product refers to a program that is a tradable product. The product can generally exist in any format, such as in paper format, or on a computer-readable data carrier and / or a computer-readable storage medium. Specifically, the computer program product can be distributed via a data network.

[0087] Finally, a modulated data signal is disclosed and proposed herein, which contains instructions readable by a computer system or a computer network for executing a method according to one or more of the embodiments disclosed herein.

[0088] With reference to the computer-implemented aspects of the present invention, one or more or even all of the method steps of the methods according to one or more of the embodiments disclosed herein may be performed using a computer or a computer network. Thus, typically, any of the method steps including the provision and / or manipulation of data may be performed using a computer or a computer network. Typically, these method steps may include any method steps, except for method steps that typically require manual work, such as providing samples and / or performing certain aspects of the actual measurement.

[0089] Specifically, this article further discloses:

[0090] - a computer or a computer network, comprising at least one processor, wherein the processor is adapted to execute the method according to one of the embodiments described in this specification,

[0091] - a computer loadable data structure, which is suitable for performing a method according to one of the embodiments described in this specification when the data structure is executed on a computer,

[0092] - a computer program, wherein the computer program is adapted to perform a method according to one of the embodiments described in this specification when the program is executed on a computer,

[0093] - a computer program comprising program means for carrying out a method according to one of the embodiments described in the present description when the computer program is executed on a computer or on a computer network,

[0094] - a computer program comprising the program means according to the preceding embodiment, wherein the program means is stored on a computer-readable storage medium,

[0095] - a storage medium, on which a data structure is stored and wherein the data structure is suitable for carrying out a method according to one of the embodiments described in the present description after being loaded into a main storage device and / or a working storage device of a computer or a computer network, and

[0096] A computer program product having program code means, wherein the program code means can be stored or stored on a storage medium for executing the method according to one of the embodiments described in the present description if the program code means is executed on a computer or a computer network.

[0097] In a further aspect of the invention, a photodetector for measuring optical radiation is disclosed. The photodetector is configured to perform the method according to the invention for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector and / or to perform the method according to the invention for determining at least one item of information about a measurement object. The photodetector comprises at least one photosensitive area and at least one readout electronics unit.

[0098] The readout electronics unit may include one or more of: at least one bias voltage source; at least one operational amplifier; at least one analog-to-digital converter; at least one voltage divider; at least one current shunt; an ASIC.

[0099] The at least one photosensitive region may include at least one photoconductive material. The photoconductive material may be selected from at least one of PbS, PbSe, Ge, InGaAs, InSb, or HgCdTe. The photosensitive region may be configured as a photoconductor or a photodiode. The photosensitive region may be optically active. The photosensitive region may generate an electrical signal when illuminated. The integrated circuit may condition, amplify and / or digitize the light-induced electrical signal. The at least one photodetector may include at least one of an evaluation unit or a communication interface, the communication interface being configured to perform at least one of the following: transmitting data from the evaluation unit or transmitting data to the evaluation unit or transmitting data within the evaluation unit. The at least one evaluation unit may be at least partially cloud-based. The at least one readout electronics unit may be wired to at least one of the at least one evaluation unit or the at least one communication interface.

[0100] The photodetector may further comprise at least one temperature stabilization device, in particular a thermoelectric cooler.

[0101] For further details about the photodetector, reference may be made to the description of the method as given above or as described in more detail below. In particular, as outlined above, the at least one photodetector may comprise an evaluation unit and / or a communication interface configured to transfer information to a computing device. As further outlined above, the evaluation unit may further be designed to fully or partially control or drive the photodetector.

[0102] In another aspect of the present invention, a spectrometer for spectrally analyzing optical radiation provided by at least one measurement object is disclosed. The spectrometer comprises:

[0103] at least one radiation source configured for emitting optical radiation at least partially towards the at least one measurement object; and

[0104] - at least one photodetector according to any of the embodiments relating to photodetectors described above or in further detail below.

[0105] As used herein, the term "spectrum" (including its grammatical variations) is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and will not be limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a partition of optical radiation, wherein the spectrum consists of an optical signal defined by a signal wavelength and a corresponding signal intensity. In particular, the spectrum may include spectral information associated with at least one measurement object, such as the type and composition of at least one material forming the at least one measurement object, which spectral information may be determined by recording at least one spectrum associated with the at least one measurement object. As used herein, the term "spectrometer" is a broad term and will be given its ordinary and conventional meaning for a person of ordinary skill in the art and will not be limited to a special or custom meaning. The term may specifically refer to, but is not limited to, a device configured to determine spectral information by recording at least one measurement of at least one signal intensity associated with at least one corresponding signal wavelength of optical radiation and evaluating at least one detector signal associated with the signal intensity.

[0106] The spectrometer may further include at least one evaluation unit. The evaluation unit may further be designed to control or drive the spectrometer or parts thereof, such as a radiation source, in whole or in part. The photodetector may include the evaluation unit. However, the evaluation unit may also be arranged at least partially outside the photodetector, such as in a spectrometer. Therefore, the spectrometer may include the evaluation unit. Additionally or alternatively, the evaluation unit may be arranged at least partially outside the spectrometer, such as in an external device (e.g., a computer, a smart phone, or a tablet computer). The evaluation unit may be at least partially based on the cloud. The spectrometer may include at least one communication interface, which is configured to perform at least one of the following: transmitting data from the evaluation unit or transmitting data to the evaluation unit or transmitting data within the evaluation unit.

[0107] The spectrometer may further comprise at least one optical filter element configured to filter the optical radiation or more specifically a selected wavelength of the optical radiation. The at least one optical filter element may specifically be positioned in the beam path before the photosensitive region. The spectrometer may comprise a plurality of photodetectors and a plurality of optical filter elements, each photodetector comprising one or more photosensitive regions. The optical filter element may be positioned in the beam path before the at least one photodetector, wherein the plurality of optical filter elements may be configured to at least partially filter different wavelengths.

[0108] For further details regarding the spectrometer, reference may be made to the description of the photodetector and method above and as described in more detail below.

[0109] In another aspect of the present invention, there is disclosed the use of a spectrometer according to any of the embodiments relating to a spectrometer described in further detail above or below for a purpose of use selected from the group consisting of: infrared detection applications; thermal detection applications; thermometer applications; heat seeking applications; flame detection applications; fire detection applications; smoke detection applications; temperature sensing applications; spectroscopy applications; exhaust gas monitoring applications; combustion process monitoring applications; pollution monitoring applications; industrial process monitoring applications; chemical process monitoring applications; food processing process monitoring applications; water quality monitoring applications; air quality monitoring applications; quality control applications; temperature control applications; motion control applications; emission control applications; gas sensing applications; gas analysis applications; motion sensing applications; chemical sensing applications; mobile applications; medical applications; mobile spectroscopy applications; food analysis applications.

[0110] As used herein, the terms "having", "including" or "comprising" or any arbitrary grammatical variant thereof are used in a non-exclusive manner. Thus, these terms may refer to the absence of additional features in the entity described in this context in addition to the features introduced by these terms, or the presence of one or more additional features. As an example, the expressions "A has B", "A includes B" and "A contains B" may refer to the absence of other elements in A in addition to B (i.e., A consists only and solely of B), or the presence of one or more additional elements in entity A in addition to B (such as element C, elements C and D or even additional elements).

[0111] Further, it should be noted that the terms "at least one", "one or more", or similar expressions indicating that a feature or element may occur once or more than once are typically used only once when introducing the corresponding feature or element. In most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" is not repeated, although the corresponding feature or element may occur once or more than once.

[0112] Further, as used herein, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features without limiting the possibilities of alternatives. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As the skilled person will recognize, the present invention can be implemented by using alternative features. Similarly, the features introduced by "in an embodiment of the present invention" or similar expressions are intended to be optional features, without any limitation on alternative embodiments of the present invention, without any limitation on the scope of the present invention, and without any limitation on the possibility of combining the features introduced in this manner with other optional or non-optional features of the present invention.

[0113] Summarizing and without excluding further possible embodiments, the following embodiments may be envisaged:

[0114] Embodiment 1: A method for determining at least one correction function for compensating for responsivity variations of at least one photodetector, wherein the photodetector comprises at least one photosensitive area and at least one readout electronics unit for reading out the photosensitive area, the method comprising the following steps:

[0115] a) determining at least one reference signal of the photodetector, wherein the photosensitive area is illuminated by optical radiation provided by at least one reference for determining the reference signal;

[0116] b) determining at least one background signal level of the photodetector;

[0117] c) determining the correction function by using at least one evaluation unit, wherein determining the correction function comprises determining a change in a background signal level and evaluating the change in the background signal level in relation to the reference signal.

[0118] Embodiment 2: The method according to the previous embodiment, wherein the background signal level and the reference signal are measured synchronously in time.

[0119] Embodiment 3: The method according to any one of the preceding embodiments, wherein the reference signal is measured online using frequency reuse during sample measurement and / or by measuring the reference signal for at least one extended period of time in the absence of sample measurement.

[0120] Embodiment 4: The method according to any one of the preceding embodiments, wherein determining the background signal level in step b) comprises determining a dark signal from a dark phase during determination of the reference signal.

[0121] Embodiment 5: The method according to any one of the preceding embodiments, wherein the background signal level and the reference signal are measured at different times.

[0122] Embodiment 6: The method according to any one of the preceding embodiments, wherein step b) comprises determining the dark signal before and / or during and / or after determining the reference signal.

[0123] Embodiment 7: The method according to the preceding embodiment, wherein the photosensitive area is covered by at least one opaque cover and / or is not illuminated.

[0124] Embodiment 8: The method according to any one of the preceding two embodiments, wherein determining the background signal level comprises extrapolating dark signals and / or modeling these dark signals.

[0125] Embodiment 9: A method according to any one of the preceding embodiments, wherein in step a), the optical radiation is modulated.

[0126] Embodiment 10: The method according to the preceding embodiment, wherein the background signal level is determined by using the time and phase of the minimum of the modulated optical radiation.

[0127] Embodiment 11: A method according to any of the preceding embodiments, wherein the method comprises retrieving at least one initial background signal level, wherein determining the change in the background signal level comprises comparing the initial background signal level with the background signal level determined in step b).

[0128] Embodiment 12: A method according to any of the preceding embodiments, wherein the method comprises measuring the reference signal and the background signal under at least two different conditions of the photodetector, wherein the condition of the photodetector is set by setting and / or adjusting the value of at least one influencing variable.

[0129] Embodiment 13: A method according to the previous embodiment, wherein the influencing variable is at least one variable that affects the dark resistance of the photosensitive area, wherein the influencing variable is at least one variable selected from the group consisting of: the temperature of the photosensitive area; the illumination of the photosensitive area; the temperature of the evaluation unit or at least a part thereof; at least one physical quantity of the photodetector or at least a part thereof, i.e., a bias voltage.

[0130] Embodiment 14: A method according to any of the preceding embodiments, wherein the change in the background signal level is determined relative to a reference signal corresponding to a zero point of the dark signal change.

[0131] Embodiment 15: A method according to any one of the aforementioned embodiments, wherein the correction function is fitted to the relationship between the change in the background signal level and the reference signal.

[0132] Embodiment 16: A method according to any of the preceding embodiments, wherein the correction function comprises at least one coefficient, wherein the correction function is a function selected from the group consisting of: a linear function; a polynomial function; an exponential function.

[0133] Embodiment 17: The method according to any of the preceding embodiments, wherein the correction function is a linear function

[0134]

[0135] Among them, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0136] Embodiment 18: A method according to any of the preceding embodiments, wherein the method comprises repeating steps a) to c) at a predefined time or continuously.

[0137] Embodiment 19: A method according to any of the preceding embodiments, wherein the method comprises compensating for changes in the responsivity of the photosensitive region caused by a physical quantity affecting the resistance of the photosensitive region.

[0138] Embodiment 20: A method according to any of the preceding embodiments, wherein the method includes compensating for changes in the responsiveness of the photosensitive area caused by at least one of the following: changes in the temperature of the photosensitive area; changes in the illumination of the photosensitive area; changes in the temperature of the evaluation unit or at least a part thereof; changes in at least one physical quantity of the photodetector or at least a part thereof.

[0139] Embodiment 21: A method according to any one of the preceding embodiments, wherein the readout electronic device unit comprises at least one bias voltage source, wherein at least one bias voltage V is applied to the photosensitive area by using the bias voltage source 偏置 to generate a dark signal.

[0140] Embodiment 22: A method according to any of the preceding embodiments, wherein the readout electronic device unit may include at least one of the following: an operational amplifier; an analog-to-digital converter; a voltage divider; a current divider, an ASIC.

[0141] Embodiment 23: A method according to any of the preceding embodiments, wherein the photodetector further comprises at least one temperature stabilization device for controlling the temperature of the photodetector or at least a portion thereof.

[0142] Embodiment 24: A method according to any of the preceding embodiments, wherein the photosensitive area comprises at least one photoconductive material.

[0143] Embodiment 25: The method according to any of the preceding embodiments, wherein the photoconductive material is selected from at least one of PbS, PbSe, Ge, InGaAs, InSb and HgCdTe.

[0144] Embodiment 26: A method according to any of the preceding embodiments, wherein the photodetector comprises the evaluation unit and / or at least one communication interface for transmitting data from the evaluation unit and / or to the evaluation unit and / or within the evaluation unit.

[0145] Embodiment 27: A method according to any of the preceding embodiments, wherein the evaluation unit is at least partially cloud-based.

[0146] Embodiment 28: A method according to any of the method embodiments described above, wherein the method is at least partially implemented by a computer.

[0147] Embodiment 29: A method for determining at least one item of information about at least one measurement object using at least one photodetector, wherein the photodetector comprises at least one photosensitive area and at least one readout electronics unit for reading out the photosensitive area, the method comprising the following steps:

[0148] i) providing optical radiation by the measurement object and determining at least one measurement signal by using the photodetector;

[0149] ii) correcting the measurement signal by using at least one evaluation unit, by using a correction function, wherein the correction function is determined by using a method according to any of the preceding embodiments relating to the method for determining at least one correction function; and

[0150] iii) determining the information about the measurement object by evaluating the corrected measurement signal using the evaluation unit.

[0151] Embodiment 30: The method according to the previous embodiment, wherein the correction function is a linear function, wherein the i-th measurement signal S meas,i The corrected signal S is corrected by the following formula corr,i ,

[0152]

[0153] in

[0154]

[0155] D1 is the initial background signal level, D2 is the background signal level used to determine the correction function, and D meas,i is the measurement signal S meas,i The background signal level, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0156] Embodiment 31: A method according to any of the preceding embodiments relating to a method for determining at least one item of information, wherein the method is at least partially implemented by a computer.

[0157] Embodiment 32: A non-transitory computer-readable medium comprising instructions, which, when executed by one or more processors, cause the one or more processors to perform at least one of the methods described in any of the method embodiments described above.

[0158] Embodiment 33: A photodetector for measuring optical radiation, the photodetector being configured to perform a method for determining at least one correction function for compensating for changes in the responsivity of at least one photodetector according to any of the aforementioned embodiments involving a method for determining at least one correction function for compensating for changes in the responsivity of at least one photodetector, and / or to perform a method for determining at least one item of information about a measured object according to any of the aforementioned embodiments involving a method for determining at least one item of information about a measured object, wherein the photodetector comprises at least one photosensitive area and at least one readout electronic device unit.

[0159] Embodiment 34: A photodetector according to the preceding embodiment, wherein the readout electronic device unit comprises one or more of: at least one bias voltage source, at least one operational amplifier; at least one analog-to-digital converter; at least one voltage divider; at least one current shunt; an ASIC.

[0160] Embodiment 35: A photodetector according to any of the aforementioned embodiments relating to photodetectors, wherein the photodetector further comprises at least one temperature stabilization device.

[0161] Embodiment 36: A photodetector according to any of the aforementioned embodiments relating to photodetectors, wherein the photosensitive area comprises at least one photoconductive material.

[0162] Embodiment 37: The photodetector according to the previous embodiment, wherein the photoconductive material is selected from at least one of PbS, PbSe, Ge, InGaAs, InSb and HgCdTe.

[0163] Embodiment 38: A photoelectric detector according to any one of the aforementioned embodiments involving photoelectric detectors, wherein the photoelectric detector includes at least one evaluation unit and / or includes at least one interface, and the at least one interface is used to transmit data from the evaluation unit and / or to the evaluation unit and / or within the evaluation unit.

[0164] Embodiment 39: A photodetector according to any of the preceding embodiments relating to photodetectors, wherein the evaluation unit is at least partially cloud-based.

[0165] Embodiment 40: A spectrometer for performing spectral analysis on optical radiation provided by at least one measurement object, the spectrometer comprising:

[0166] - at least one radiation source configured for emitting optical radiation at least partially towards the measurement object; and

[0167] - at least one photodetector according to any of the preceding embodiments relating to photodetectors.

[0168] Embodiment 41: The spectrometer according to the previous embodiment, wherein the spectrometer further comprises at least one evaluation unit, wherein the evaluation unit is further configured to generate at least one item of spectral information about the measurement object.

[0169] Embodiment 42: The spectrometer according to the preceding embodiment, wherein the evaluation unit is further configured to control the radiation source.

[0170] Embodiment 43: A spectrometer according to any one of the aforementioned embodiments relating to a spectrometer, wherein the radiation source is a modulated radiation source.

[0171] Embodiment 44: The spectrometer according to any of the preceding embodiments relating to a spectrometer, wherein the radiation source comprises at least one of a semiconductor-based radiation source and a thermal radiator.

[0172] Embodiment 45: The spectrometer described in any of the aforementioned embodiments related to the spectrometer further includes at least one optical filter element.

[0173] Embodiment 46: Use of the spectrometer described in any of the aforementioned embodiments involving spectrometers for a purpose of use selected from the group consisting of: infrared detection applications; thermal detection applications; thermometer applications; heat seeking applications; flame detection applications; fire detection applications; smoke detection applications; temperature sensing applications; spectroscopy applications; exhaust gas monitoring applications; combustion process monitoring applications; pollution monitoring applications; industrial process monitoring applications; chemical process monitoring applications; food processing process monitoring applications; water quality monitoring applications; air quality monitoring applications; quality control applications; temperature control applications; motion control applications; emission control applications; gas sensing applications; gas analysis applications; motion sensing applications; chemical sensing applications; mobile applications; medical applications; mobile spectroscopy applications; food analysis applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0174] Other optional features and embodiments are preferably disclosed in more detail in the subsequent description of the embodiments in conjunction with the dependent claims. Wherein, as the skilled person will recognize, the corresponding optional features can be implemented in an independent manner and in any arbitrary feasible combination. The scope of the present invention is not limited by the preferred embodiments. The embodiments are schematically depicted in the accompanying drawings. Wherein, the same reference numerals in these drawings represent the same or functionally equivalent elements.

[0175] In the attached picture:

[0176] Figure 1Schematically illustrates an exemplary embodiment of a spectrometer according to the present invention;

[0177] FIG. 2A to FIG. 2B schematically illustrates an exemplary embodiment of a photodetector according to the present invention;

[0178] Figure 3 A flow chart illustrating an exemplary embodiment of a method for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector;

[0179] FIG. 4A to FIG. 5B shows experimental results of measuring an exemplary embodiment of a spectrometer according to the present invention; and

[0180] Figure 6 A flow chart of an exemplary embodiment of a method for determining at least one item of information about a measurement object is shown. DETAILED DESCRIPTION

[0181] Figure 1 An exemplary embodiment of a spectrometer 110 according to the present invention is schematically shown. The spectrometer 110 is configured to perform a spectral analysis on an optical radiation 112 provided by at least one measurement object 114. The spectrometer 110 can be a device configured to determine spectral information by recording at least one measurement value of at least one signal intensity associated with at least one corresponding signal wavelength of the optical radiation 112 and evaluating at least one detector signal associated with the signal intensity. The measurement object 114 can be any body selected from a living body and an inanimate body. The measurement object 114 can specifically include at least one material under investigation. The measurement object 114 can generally refer to an object to be measured (for example, for which a spectrum is to be recorded), wherein the measurement object 114 can have any property in principle (for example, any optical property or any shape). The measurement object 114 can include at least one solid or fluid sample.

[0182] The spectrometer 110 includes at least one radiation source 116 configured to emit optical radiation 112 at least partially toward at least one measurement object 114. The radiation source 116 may be a device configured to emit optical radiation 112. The radiation source 116 may be configured to emit optical radiation 112 toward the measurement object 114, such as optical radiation in the form of a light beam 118, such as Figure 1Indicated. Alternatively or additionally, the radiation source 116 can be configured to emit the optical radiation 112 isotropically (e.g., uniformly in all spatial directions), wherein only a portion of the emitted optical radiation 112 can illuminate the measurement object 114. The radiation source 116 can include at least one of a semiconductor-based radiation source or a thermal radiator. At least one semiconductor-based radiation source can be selected from at least one of a light emitting diode (LED) or a laser (in particular, a laser diode). The LED can include at least one fluorescent and / or phosphorescent material. The thermal radiator can include at least one of an incandescent lamp, a black body emitter, and a microelectromechanical system (MEMS) emitter. The radiation source 116 can be a modulated radiation source 119. Therefore, the optical radiation 112 can be modulated. Modulation can include a process of changing, in particular, periodically changing, at least one characteristic of the optical radiation 112, in particular, one or both of the intensity or phase of the optical radiation 112. The modulation can be a complete modulation from a maximum value to zero, or can be a partial modulation from a maximum value to an intermediate value greater than zero.

[0183] The spectrometer 110 includes at least one photodetector 120 according to any of the embodiments involving the photodetector 120 described in further detail above or below. Figure 2A and Figure 2B , these figures individually schematically illustrate exemplary embodiments of a photodetector 120 according to the present invention. Specifically, Figure 2A indicates the settings of the photodetector 120, and Figure 2B A circuit diagram corresponding to a photodetector 120 is indicated. The photodetector 120 is configured for performing a method according to the invention for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector and / or for performing a method according to the invention for determining at least one item of information about a measurement object. The photodetector 120 comprises at least one photosensitive area 122 and at least one readout electronics unit 124.

[0184] The photodetector 120 may be an optical detector or sensor configured to detect the optical radiation 112, such as for detecting illumination and / or a light spot generated by at least one light beam 118. The photodetector 120 may include at least one substrate. A single photodetector 120 may be a substrate having at least one single photosensitive region 122 that generates a physical response to illumination of a given wavelength range. The photodetector 120 may include a plurality of photosensitive regions 122 that may be arranged in at least one of an array or a matrix. The photosensitive region 122 may be a unit of the photodetector 120 configured for illumination, or in other words for receiving the optical radiation 112, and for generating at least one signal (such as an electronic signal) in response to the illumination. The photosensitive region 122 may be located on a surface of the photodetector 120. The photosensitive region 122 may specifically be a single, closed, uniform photosensitive region 122. At least one photosensitive region 122 may include at least one photoconductive material. The photoconductive material may be selected from at least one of PbS, PbSe, Ge, InGaAs, InSb, or HgCdTe. The photosensitive region 122 may be configured as a photoconductor or a photodiode. The photosensitive region 122 may be optically active. The photosensitive region 122 may generate an electrical signal when illuminated. The integrated circuit may condition, amplify, and / or digitize the light-induced electrical signal.

[0185] The readout electronics unit 124 may be an electronics unit configured to quantify and / or process at least one physical property and / or a change in at least one physical property detected by the photodetector 120 or more specifically the photosensitive region 122. Figure 2B As indicated, the readout electronics unit 124 may include at least one of: an operational amplifier 126; an analog-to-digital converter 128; a voltage divider; a current divider, an ASIC, specifically for subtracting a constant current I q To generate a signal current I S The photodetector 120 may include a bias voltage source 130. The bias voltage source 130 may be a voltage source configured to generate a bias voltage. The bias voltage source 130 may be configured to apply at least one (e.g., constant) bias voltage V to the photodetector 120, specifically to the photosensitive region 122 (which may be considered a resistor in this context). 偏置 The bias voltage V can be applied to the photosensitive region 122 by using a bias voltage source 130 偏置 To generate dark signals, especially dark current I D . Dark current I D can flow through the photodetector 122, where I D =V 偏置 / R D , where V 偏置 is the bias voltage, and RD is the dark resistance. The readout electronics unit can be configured to read the dark current I D Subtract the constant current I q , which gives the signal current I S =I D –I q . Signal current I S V may be amplified by front-end electronics such as operational amplifier 126 and then may use analog-to-digital converter 128 to generate a digital signal S. 偏置 Changes in may cause changes in responsivity, which can be corrected by using the compensation method according to the present invention.

[0186] Compensation may be the elimination or correction of a physical effect, in particular a disturbing influence or interference or disturbance. Compensation may be or may include a measure for a disturbance. In particular, compensation may be temperature compensation, wherein the temperature or more particularly a temperature change may be, for example, a disturbance for the detector. As an example, the responsivity of the photodetector 120 may be temperature dependent. Thus, changes in the ambient temperature of the photosensitive region 122 may result in additional changes in the detector signal that are not responsive to the illumination of the photodetector 120. In other words, the detector signal may be subject to temperature drift. Responsivity may include a relationship between at least one input and at least one output of the photodetector 120. Responsivity may be a relationship between an optical input and an electrical output. Responsivity may measure an electrical output (e.g., photocurrent or resistance) for each optical input (e.g., light intensity or irradiance). Responsivity may also be referred to as photosensitivity. Responsivity changes may include any deviations in responsivity, such as any deviations in responsivity determined relative to a predefined value and / or at different points in time.

[0187] The at least one photodetector 120 or at least the spectrometer 110 may comprise at least one of an evaluation unit 132 or a communication interface 134, which is configured to perform at least one of the following: transfer data from or to or within the evaluation unit 132. Additionally or alternatively, the evaluation unit 132 may be at least partially arranged outside the spectrometer 110, such as in an external device (e.g., a computer, a smartphone or a tablet). The evaluation unit 132 may be a device configured to analyze or interpret data, in particular to determine at least one qualitative or quantitative information. The information may be obtained in particular by evaluating at least one detector signal generated by the at least one photodetector 120. The evaluation unit 132 may be or may comprise at least one of an integrated circuit, in particular an application specific integrated circuit (ASIC), or a data processing device, in particular at least one of a digital signal processor (DSP), a field programmable gate array (FPGA), a microcontroller, a microcomputer, a computer or an electronic communication unit (in particular a smartphone or a tablet). Further components may be feasible, in particular at least one preprocessing device or a data acquisition device. Further, the evaluation unit 132 may include at least one interface, in particular at least one of a wireless interface or a wired interface. Further, the evaluation unit 132 may be designed to completely or partially control or drive another device, such as at least one photodetector 120 or a spectrometer 110 or a part thereof, such as a radiation source 116. The information as determined by the evaluation unit 132 may be provided to at least one of another device or a user in at least one of an electronic, visual, auditory or tactile manner. Further, the information may be stored in at least one data storage unit, specifically in an internal data storage unit such as included by the photodetector 120 or at least the spectrometer 110, in particular by at least one evaluation unit 132, or in a separate storage unit to which the information may be transmitted via at least one interface. At least one electronic communication unit may include the separate storage unit. The storage unit may be particularly configured to store at least one electronic table, such as at least one lookup table.

[0188] The evaluation unit 132 can preferably be configured to execute at least one computer program, in particular at least one computer program that executes or supports the steps of the method according to the invention. For this purpose, the evaluation unit 132 can in particular include at least one data processing device, in particular at least one of an electronic data processing device or an optical data processing device. The processing device can be designed to determine the correction function.

[0189] At least one evaluation unit 132 may be at least partially cloud-based. In other words, at least one evaluation unit 132 may be at least partially distributed in at least one cloud 136 for at least one of cloud computing or cloud storage. At least one cloud 134 may specifically include at least one external device 138, such as a computer or a computer network. Figure 1 and Figure 2A As shown, at least one evaluation unit 132 can be at least partially distributed within the photodetector 120, for example, for performing a first signal processing of the detector signal read out by the at least one readout electronics unit 124, such as for signal filtering or signal smoothing. Additional signal processing or signal evaluation can be performed in a part of at least one evaluation unit 132 distributed on at least one external device 138 of at least one cloud 136. At least one external device 138 can specifically include a larger computing power or data storage capacity. Additionally or alternatively, at least one external device 138 can be more user-friendly or mobile, such as a smartphone. The external devices 138 can be arbitrarily distributed in space. The external devices 138 can change over time, in particular according to demand. The external devices 138 can be interconnected by using the Internet or an intranet. Different parts of the at least one evaluation unit 132 can be at least partially interconnected by at least one communication interface 134. The communication interface 134 can be at least one of wireless or wired.

[0190] The communication interface 134 can be an article or element that forms a boundary configured for transferring information. In particular, the communication interface 134 can be configured to transfer information from a computing device (e.g., a computer), such as to send or output information to, for example, another device. Additionally or alternatively, the communication interface 134 can be configured to transfer information to a computing device, such as to a computer, such as to receive information. The communication interface 134 can specifically provide a means for transferring or exchanging information. In particular, the communication interface 134 can provide a data transfer connection, such as Bluetooth, NFC, inductive coupling, etc. As an example, the communication interface 134 can be or can include at least one port, the at least one port including one or more of a network or Internet port, a USB port, and a disk drive. The communication interface 134 can be at least one web interface. At least one readout electronic device unit 124 can be wired to at least one of the at least one evaluation unit or at least one communication interface 134, such as by using a wire 140.

[0191] The photodetector 120 may further include at least one temperature stabilization device 142. The temperature stabilization device 142 may be an element or device configured to keep the temperature of another element or device constant or smooth or stable. Specifically, at least one temperature stabilization device 142 may be configured to stabilize the temperature of the photodetector 120. The temperature stabilization device 142 may be configured to maintain the temperature of a component of the photodetector 120, such as the photosensitive region 122 and / or the readout electronics unit 124, at a predetermined level. The temperature stabilization device 142 may be configured to stabilize the temperature of a component of the photodetector 120, such as the photosensitive region 122 and / or the readout electronics unit 124. The temperature stabilization device 142 may be configured to stabilize the temperature of another component of the spectrometer 110, specifically the radiation source 116. The temperature stabilization device 142 may be wired to at least one of the photodetector and the radiation source 116. The temperature stabilization device 142 may be or include at least one thermoelectric cooler 144. Thermoelectric cooler 144 can be an electrically driven heat pump configured to transfer heat between at least two spatial regions, thereby generating a heat flux between the at least two spatial regions. Specifically, thermoelectric cooler 144 can be based on the Peltier effect to generate heat flux. For this purpose, thermoelectric cooler 144 can include at least one Peltier element in particular. The direction of the heat flux can depend on the direction of the current applied to thermoelectric cooler 144. Depending on the direction of the heat flux, thermoelectric cooler 144 can be used to cool at least one spatial region by transferring heat to at least one other spatial region, or to heat the spatial region by transferring heat from at least one other spatial region.

[0192] The spectrometer 110 may further include at least one optical filter element 146 configured to filter the optical radiation 112 or more specifically a selected wavelength of the optical radiation 112. The at least one optical filter element may be specifically positioned in the beam path before the photosensitive region 122. The spectrometer 110 may include a plurality of photodetectors 120 and a plurality of optical filter elements 146, each photodetector including one or more photosensitive regions 122. The optical filter element 146 may be positioned in the beam path before the at least one photodetector 120, wherein the plurality of optical filter elements 146 may be configured to at least partially filter different wavelengths. The spectrometer 110 may further include at least one housing 148 surrounding at least part of the spectrometer 110, such as the photodetector 120 and / or the radiation source 116. The external device 138 of the cloud 134 may be arranged outside the housing 148. The housing 142 may include at least one window 150. The at least one window 150 may be at least partially transparent to the optical radiation 112.

[0193] In the following, reference will be made to Figure 1 An exemplary beam path of optical radiation 112 is described. At least one radiation source 116 can emit optical radiation 112 as incident optical radiation 152 toward a measurement object 114 through a window 150. The measurement object 114 can reflect (particularly diffusely reflect) the incident optical radiation 152 at least partially toward a photosensitive region 122 of a photodetector 120 in the form of reflected optical radiation 154. Further, the measurement object 114 can at least partially absorb the incident optical radiation 152, which can indicate at least one physical property or chemical composition of the measurement object 114. The reflected optical radiation 154 can pass through the window 150 and the optical filter element 146 before reaching the photodetector 120, which can generate a corresponding signal. In the described beam path, the measurement object 114 can be easily replaced by a reference 156 having known optical properties, which is typically used for calibration purposes, for example. In general, the reference 156 can be an arbitrary object. In particular, the reference 156 can have at least one known physical property, in particular at least one optical property. However, the reference 156 can also have unknown physical properties, for example. For example, the reference 156 may be a sample to be measured, such as the measurement object 114 .

[0194] Figure 3 A flow chart of an exemplary embodiment of a method for determining at least one correction function for compensating for responsivity variations of a photodetector 120 is shown. The photodetector 120 comprises a photosensitive area 122 and a readout electronics unit 124 for reading out the photosensitive area 122. The method comprises the following steps:

[0195] a) (indicated by reference numeral 158) determining at least one reference signal of the photodetector 120, wherein the photosensitive region 122 is illuminated by optical radiation 112 provided by at least one reference 156 for determining the reference signal;

[0196] b) (indicated by reference numeral 160) determining at least one background signal level of the photodetector 120;

[0197] c) (denoted by reference numeral 162) determining a correction function by using the at least one evaluation unit 132, wherein determining the correction function comprises determining a change in a background signal level and evaluating the change in the background signal level in relation to a reference signal.

[0198] Method steps a) to c) may be performed in the order indicated. However, it should be noted that a different order is also possible. The method may include additional method steps that are not listed. Further, one or more of method steps a) to c) may be performed once or repeatedly. Further, two or more of method steps a) to c) may be performed simultaneously or in a time-overlapping manner. The method may include repeating steps a) to c) at a predefined time or continuously.

[0199] The method for determining at least one correction function for compensating for changes in the responsivity of the photodetector 120 can be at least partially implemented by a computer. The computer-implemented method can be a method involving at least one computer and / or at least one computer network. The computer and / or the computer network may include at least one processor, which may be configured to perform at least one method step of the method according to the present invention. In particular, each of these method steps is performed by a computer and / or a computer network. The method can be performed fully automatically, in particular without user interaction.

[0200] The method may comprise compensating for changes in the responsivity of the photosensitive area 122 caused by a physical quantity influencing the resistance, in particular the dark resistance, of the photosensitive area 122. The method may comprise compensating for changes in the responsivity of the photosensitive area 122 caused by at least one of: a change in the temperature of the photosensitive area 122; a change in the illumination of the photosensitive area 122, in particular a change in the illumination of the photosensitive area due to at least one background radiation; a change in the temperature of the evaluation unit 132 or at least a part thereof; a change in at least one physical quantity, in particular the temperature, of the photodetector 120 or at least a part thereof, in particular at least one optional further electronic component of the photodetector 120, as described above or as described in more detail below.

[0201] The reference signal may be a signal generated by the photodetector 120 in response to illumination by the optical radiation 112 provided by the reference 156. Specifically, the reference signal may be generated by the photosensitive region 122 in response to illumination. The reference signal may be or include at least one signal generated at a single point in time. The reference signal may be or include at least one signal generated over a period of time. The reference signal may be or include at least one pre-processed signal, such as a filtered or smoothed or amplified signal. The reference signal may be or include at least one of an analog signal or a digital signal.

[0202] Step a) may comprise determining a plurality of reference signals. For example, the reference signal may be determined for: different conditions of the photodetector 120, in particular one or more of different temperatures of the photosensitive area 122; different illumination of the photosensitive area 122; different temperatures of the evaluation unit 132 or at least parts thereof; different physical quantities of the photodetector 120 or at least parts thereof, in particular different physical quantities of at least one optional further electronic component of the photodetector as described above or in further detail below, i.e. different bias voltages. The reference signal may be determined at different times. For example, the reference signal may be determined for different predefined temperatures.

[0203] The reference signal may be measured online using frequency multiplexing during the sample measurement and / or in the absence of sample measurement by measuring the reference signal for at least one extended period of time. For example, different frequencies may be used for the sample measurement and the measurement of the reference signal. For example, the optical radiation in step a) may be modulated. Additionally or alternatively, the reference signal may be measured before or after the sample measurement.

[0204] FIG. 4A to FIG. 5B Experimental results of measurements on an exemplary embodiment of spectrometer 110 are shown. Figure 4A Signal traces of a modulated reference signal at two different detector temperatures over a time t of 1000 ms are shown. The signal S is recorded digitally in counts. The dark current is extracted from the dark phase and extrapolated for the light phase, as will be described in further detail below. The modulated reference signal at a photodetector temperature of 21.927°C is represented by reference numeral 164. The corresponding modeled background signal at a photodetector temperature of 21.927°C is represented by reference numeral 166. The modulated reference signal at a photodetector temperature of 21.543°C is represented by reference numeral 168. The corresponding modeled background signal at a photodetector temperature of 21.543°C is represented by reference numeral 170. As can be seen, the difference in photodetector temperature reflects the difference in modeled background signals 168 and 170. Figure 4B In FIG. 1 , a background signal model of the modulated reference signal 164 is formed by using the time intervals before and after recording the modulated reference signal 164. The corresponding further modeled background signal at a photodetector temperature of 21.927°C is denoted by reference numeral 172.

[0205] The background signal may be a signal generated by the photodetector 120 that is independent of illumination. For example, in order to determine the background signal, the photosensitive area 122 may be covered by at least one opaque cover and / or not illuminated. Figure 4AAs indicated, when modulated light radiation is used, the photosensitive region 122 may not be illuminated at least for a predefined time interval. The modulation may be a full modulation down to zero intensity, so that the photosensitive region 122 may not be illuminated at a minimum value of the intensity of the modulated light radiation. For example, in the case of not being illuminated, the photosensitive region 122 may be configured to generate a background signal. The background signal may be a signal generated by the photosensitive region 122, wherein illumination of the photosensitive region 122 is suppressed when the background signal is generated. The background signal may depend on at least one intrinsic property of the photosensitive region 122, in particular a material property of at least one semiconductor comprised by the photosensitive region 122. The background signal may in particular depend on the temperature of the photosensitive region 122. The background signal may include a dark signal, in particular a dark current. The dark current may be thermally induced by spontaneous formation of free charge carriers in the semiconductor of the photosensitive region 122.

[0206] The background signal level may be an average of the minimum values ​​of the background signal. In step a), the optical radiation 112 may be modulated. The background signal level may be determined by using the time and phase of the minimum value of the modulated optical radiation 112. Determining the background signal level may include extrapolating a dark signal and / or modeling the dark signal. For example, the dark signal may be extracted only from the dark phase. The extrapolation may include, for example, extrapolating to a time when the background signal is not determined during illumination of the photosensitive area, for example during determination of a reference signal and / or during sample measurement. Modeling the measured dark signal may include, for example, fitting the measured dark signal using a predefined fitting function to the identified minimum value. For example, the predefined fitting function may be a linear function.

[0207] The method may comprise measuring a reference signal and a background signal, in particular both, under at least two different conditions of the photodetector 120. The conditions of the photodetector 120 may be set by setting and / or adjusting the value of at least one influencing variable. The influencing variable may be at least one variable influencing the dark resistance of the photosensitive region 122. The influencing variable may be at least one variable selected from the group consisting of: the temperature of the photosensitive region 122; the illumination of the photosensitive region 122; the temperature of the evaluation unit 132 or at least a part thereof; at least one physical quantity of the photodetector 120 or at least a part thereof, in particular at least one optional further electronic component of the photodetector 120 described above or in further detail below, i.e. a bias voltage.

[0208] The background signal level and the reference signal can be measured synchronously in time, so that the determination of the reference signal and the dark signal can be performed in the same measurement and / or at the same time. The synchronous measurement can be performed not only by using the time information of the signals measured synchronously in time, but also by using the phase information. Figure 4CThe modulated reference signal 164 is shown as a phased signal curve, where the phase P is measured in ms. From the phased signal curve, specifically from the indicated intervals around the 6ms phase, a background signal model 174 is derived. The signal S measured synchronously in time can be described as a complex polynomial S(phase,t)=P1(phase)+P2(t), where P1 and P2 are polynomials as functions of phase and time, respectively. P1 can be selected so that it reaches 0 at the phase of the minimum signal; then, P2 describes the dark signal over time so that the dark signal can be modeled. The method may include considering the complete synchronous measurement signal or only a portion of the synchronous measurement signal. For example, a portion of the synchronous measurement signal that is away from the minimum phase by about a predefined limit (e.g., about ±1ms) can be used for dark signal modeling. The optimization of the problem and the analytical description for dark signal modeling may depend on one or more of the modulation form, frequency and signal decay time and the light source used. Measuring synchronously in time may allow online calibration, i.e., calibration during operation of the photodetector 120. Measuring synchronously in time may allow preventing the need for additional calibration time and thus improve measurement efficiency.

[0209] For example, determining the background signal level in step b) may include determining a dark signal from a dark phase during the determination of the reference signal. The dark phase may be a time range in which the photosensitive area is covered by at least one opaque cover and / or is not illuminated. For example, the dark signal may be extracted from the dark phase and may be extrapolated for the phase in which the illumination is incident on the photosensitive area 122. For example, the background signal level and the reference signal may be measured at different times. For example, step b) may include determining the dark signal before and / or during and / or after determining the reference signal.

[0210] The method may use the dark current together with a reference signal that is not necessarily time synchronized to correct for responsivity variations. As outlined above, the determination of the dark signal may be performed during the dark phase so that no additional measurements are required before and / or after the sample measurement. This may allow even small scale variations (i.e., time scales below the measurement time) to be tracked. In addition, the method may include determining the dark signal before and / or between and / or after the modulation measurement so that the dark signal is determined in true darkness throughout the measurement period. The determination of the coefficients of the correction function may be performed by actively tracking the reference signal and the dark signal in an online manner. This may be achieved by frequency multiplexing or by tracking the reference over an extended period of time without obtaining a sample measurement.

[0211] Figure 5AThe reference signal level corresponding to the modulated reference signal 164 is indicated plotted against the modeled variation Δ of the background signal. The reference signal level is specifically indicated by means of a raw amplitude 176 obtained via a Fast Fourier Transform at the modulation frequency. A correction function, denoted by reference numeral 178, is fitted to the raw amplitude for obtaining a corresponding corrected amplitude 180. The amplitude A and the modeled variation Δ are likewise indicated in counts. Figure 5B The case of a temperature-stabilized photodetector 120 is indicated similarly. Even in this case, signal drift is visible and is usually caused by electronic drift. Figure 5B In the example, the amplitude A directly varies with the dark current I measured in counts. D draw.

[0212] The correction function may be a mathematical function for compensating for variations in the responsivity of the photodetector 120. The correction function may include at least one coefficient. The correction function may be a function selected from the group consisting of: a linear function; a polynomial function; an exponential function. The correction function 178 may be applied to correct any measurement signal (including sample measurements) at its corresponding dark signal level.

[0213] Determining the correction function comprises determining a change in the background signal level. The method according to the present invention may comprise retrieving at least one initial background signal level. Retrieving the initial background signal level may comprise measuring and / or using a predefined (e.g., stored) value, such as a value retrieved from a lookup table. For example, the initial background level may be a background level at a predefined reference temperature (e.g., at 20° C.). Determining a change in the background signal level comprises comparing the initial background signal level with the background signal level determined in step b).

[0214] Determining the correction function includes evaluating the relationship between the change in the background signal level and the reference signal. The change in the background signal level can be determined relative to the reference signal corresponding to the zero point of the dark signal change. The correction function can be determined by fitting the correction function to the relationship between the change in the background signal level and the reference signal, thereby determining the parameters of the correction function. The correction function can be fitted to the relationship between the reference signal and the modeled change in the dark signal. For example, the correction function is a linear function

[0215]

[0216] Among them, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0217] For example, the method can be used to compensate for systematic changes in dark resistance. Any change in dark resistance may result in a change in dark current, and thus a change in signal current will be seen. Changes in dark resistance may be caused by changes in detector temperature, but also by background light or any other amount that may affect the resistance of the photodetector 120 itself. In fact, the method according to the present invention can allow a universal correction scheme for all resistance change modes. Further, any signal or current caused by the light signal on the photodetector 120 can be obtained, because these signals or currents also affect the resistance of the detector. The light signal can be modulated to achieve efficient signal processing that distinguishes the signal from the dark signal and noise and system drift. Long-term stability can change over time, but using a defined reference signal level, online calibration may be feasible by using the method according to the present invention. The background signal level and the reference signal can be determined in a modulated manner and / or by monitoring the dark phase during the sample measurement (e.g., before / after the sample measurement). Changes in responsiveness (photosensitivity) can be determined based on changes in the dark signal / current as monitored by (changes in) the reference signal. In order to obtain a more accurate calibration, repeated calibration measurements can be obtained.

[0218] For example, the method according to the invention can be used to compensate the current I q and / or bias voltage V 偏置 The system drift of I can be avoided, especially when using a stable detector. The dark resistance can be kept stable by means of, for example, a thermoelectric cooler 144. System drift can be caused, for example, by changes in environmental conditions, such as changes in the temperature of electronic components other than the photodetector 120 itself. Under the condition of constant dark resistance, I q or I D Any change in V 偏置 changes in S The change in and thus the change in the digital signal S. For a photoresistor, the responsivity can be determined by the basic detector characteristics and the applied bias voltage V 偏置 Therefore, V 偏置 A change in φ may result in a change in the responsivity. Therefore, the method according to the invention can also be applied to compensate for such systematic drifts in the electronics when mapping changes in the dark signal.

[0219] Figure 6 A flow chart of an exemplary embodiment of a method for determining at least one item of information about a measurement object 114 using a photodetector 120 is shown. The photodetector 120 comprises a photosensitive area 122 and a readout electronics unit 124 for reading out the photosensitive area 122. The method comprises the following steps:

[0220] i) (indicated by reference numeral 182 ) providing optical radiation 112 by a measurement object 114 and determining at least one measurement signal by using a photodetector 120 ;

[0221] ii) (indicated by reference numeral 184) correcting the measurement signal by using the evaluation unit 132 using a correction function, wherein the correction function is determined by using the method according to the invention for determining at least one correction function; and

[0222] iii) (indicated by reference numeral 186 ) determining information about the measurement object 114 by using the evaluation unit 132 by evaluating the corrected measurement signal.

[0223] Method steps i) to iii) can be performed in the order indicated. However, it should be noted that a different order is also possible. The method may include additional method steps that are not listed. Further, one or more of method steps i) to iii) can be performed once or repeatedly. Further, two or more of method steps i) to iii) can be performed simultaneously or in a time-overlapping manner.

[0224] The measurement information may be knowledge or evidence that provides a qualitative and / or quantitative description related to at least one measurement, specifically to the measurement object 114. The measurement information may include at least one of a physical property of the measurement object 114 or a chemical composition of the measurement object 114. The physical property may specifically include an optical property, such as at least one absorbance of the measurement object 114 and / or at least one emissivity of the measurement object 114. The chemical composition may specifically refer to qualitative and / or quantitative information about at least one material included in the measurement object 114.

[0225] In step i), the optical radiation 112 provided by the at least one measurement object 114 may include a wavelength of 300 nm to 3000 nm, specifically 500 nm to 2500 nm, more specifically 1400 nm to 2000 nm. The providing may include at least one of the following: reflection, specifically diffuse reflection, diffraction, transmission and emission of the optical radiation 112. The optical radiation 112 provided by the measurement object 114 may indicate at least one of a physical property of the measurement object 114 (e.g., an optical property and / or a temperature of the measurement object 114) and a chemical property of the measurement object 114 (e.g., a chemical composition of the measurement object 114). As an example, the optical radiation 112 provided by the measurement object 114 may be emitted by the at least one measurement object 114, specifically at least partially emitted toward the photodetector 120. Further, the optical radiation 112 provided by the at least one measurement object 114 may be reflected, for example diffusely reflected, by the at least one measurement object 114 at least partially toward the at least one photodetector 120. Furthermore, the optical radiation 112 provided by the at least one measurement object 114 may be transmitted through the at least one measurement object 114 and at least partially directed toward the at least one photodetector 120. However, the at least one measurement object 114 may also at least partially absorb the optical radiation 112, which may specifically indicate at least one physical property of the at least one measurement object 114 and / or at least one chemical property of the at least one measurement object 114, such as the chemical composition of at least one material forming the at least one measurement object 114.

[0226] Step ii) comprises correcting the measurement signal by using the evaluation unit 132, by using a correction function. The correction function is determined by using the method for determining at least one correction function according to the invention. For further details about the method for determining at least one item of measurement information, reference may be made to the description of the method for determining at least one correction function as described above or described in more detail below.

[0227] Step iii) determines information about the measurement object 114 by evaluating the corrected measurement signals using the evaluation unit 132. For example, the correction function is a linear function, where the i-th measurement signal S meas,i The corrected signal S is corrected by the following formula corr,i ,

[0228]

[0229] in

[0230]

[0231] D1 is the initial background signal level, D2 is the background signal level used to determine the correction function, and D meas,i is the measurement signal Smeas,i The background signal level, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

[0232] The method for determining at least one measurement information can be at least partially implemented by a computer. With reference to the computer-implemented aspects of the present invention, one or more or even all of the method steps of one or more of the methods of the embodiments disclosed herein can be performed using a computer or a computer network. Therefore, generally, any of the method steps including the provision and / or manipulation of data can be performed using a computer or a computer network. Generally, these method steps can include any method steps, except for method steps that generally require manual work, such as providing samples and / or performing certain aspects of the actual measurement.

[0233] List of Reference Numerals

[0234] 110 Spectrometer

[0235] 112 Light Radiation

[0236] 114 Measurement Objects

[0237] 116 Radiation Source

[0238] 118 Beam

[0239] 119 Modulated Radiation Source

[0240] 120 Photodetector

[0241] 122 Photosensitive area

[0242] 124 Readout electronics unit

[0243] 126 Operational Amplifier

[0244] 128 Analog-to-digital converter

[0245] 130 Bias voltage source

[0246] 132 evaluation units

[0247] 134 Communication Interface

[0248] 136 Cloud

[0249] 138 External Devices

[0250] 140 Wire

[0251] 142 Temperature stabilization equipment

[0252] 144 Thermoelectric Cooler

[0253] 146 Optical filter elements

[0254] 148 Housing

[0255] 150 Window

[0256] 152 Incident radiation

[0257] 154 Reflected light radiation

[0258] 156 References

[0259] 158 Method step a)

[0260] 160 Method step b)

[0261] 162 Method step c)

[0262] 164 Modulated reference signal at photodetector temperature of 21.927°C

[0263] 166 Modeled background signal at photodetector temperature of 21.927°C

[0264] 168 Modulated reference signal at photodetector temperature of 21.543°C

[0265] 170 Modeled background signal at photodetector temperature of 21.543°C

[0266] 172 Additional modeled background signal at photodetector temperature of 21.927°C

[0267] 174 Background signal model based on phase-controlled signal curve

[0268] 176 Original Amplitude

[0269] 178 Correction function fitted to the original amplitude

[0270] 180 corrected amplitude

[0271] 182 Method Step i)

[0272] 184 Method step ii)

[0273] 186 Method step iii)

Claims

1. A method for determining at least one correction function for compensating for variations in the responsivity of at least one photodetector (120), wherein: The photodetector (120) comprises at least one photosensitive area (122) and at least one readout electronics unit (124) for reading out the photosensitive area (122), the method comprising the following steps: a) determining at least one reference signal of the photodetector (120), wherein the photosensitive area (122) is illuminated by optical radiation (112) provided by at least one reference (156) for determining the reference signal; b) determining at least one background signal level of the photodetector (120); c) determining the correction function by using at least one evaluation unit (132), wherein determining the correction function comprises determining a change in a background signal level and evaluating the change in the background signal level in relation to the reference signal.

2. The method according to the preceding claim, wherein: The background signal level and the reference signal are measured synchronously in time, wherein measuring synchronously in time comprises determining the reference signal and the background signal level in the same measurement and / or at the same time.

3. A method according to any one of the preceding claims, wherein: The reference signal is measured online using frequency reuse during sample measurements and / or by measuring the reference signal for at least one extended period of time in the absence of sample measurements.

4. A method according to any one of the preceding claims, wherein: Determining the background signal level in step b) comprises determining a dark signal from a dark phase during determination of the reference signal.

5. A method according to any one of the preceding claims, wherein: Step b) comprises determining the dark signal before and / or during and / or after determining the reference signal.

6. A method according to any one of the preceding claims, wherein: In step a), the optical radiation (112) is modulated, wherein the background signal level is determined by using the time and phase of a minimum of the modulated optical radiation (112).

7. A method according to any one of the preceding claims, wherein: The method comprises measuring the reference signal and the background signal under at least two different conditions of the photodetector (120), wherein the condition of the photodetector (120) is set by setting and / or adjusting the value of at least one influencing variable, wherein the influencing variable is at least one variable influencing the dark resistance of the photosensitive area (122), wherein the influencing variable is at least one variable selected from the group consisting of: the temperature of the photosensitive area (122); the illumination of the photosensitive area (122); the temperature of the evaluation unit (132) or at least a part thereof; at least one physical quantity of the photodetector (120) or at least a part thereof, namely a bias voltage.

8. A method according to any one of the preceding claims, wherein: The correction function is fit to the variation of the background signal level versus the reference signal.

9. A method according to any one of the preceding claims, wherein: The correction function is a linear function Among them, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

10. A method for determining at least one item of information about at least one measurement object (114) using at least one photodetector (120), wherein: The photodetector (120) comprises at least one photosensitive area (122) and at least one readout electronics unit (124) for reading out the photosensitive area (122), the method comprising the following steps: i) providing optical radiation by the measurement object (114) and determining at least one measurement signal by using the photodetector (120); ii) correcting the measurement signal by using at least one evaluation unit (132) by using a correction function, wherein the correction function is determined by using a method according to any of the preceding claims relating to a method for determining at least one correction function; and iii) determining information about the measurement object (114) by evaluating the corrected measurement signal using the evaluation unit (132).

11. The method according to the preceding claim, wherein: The correction function is a linear function, where the i-th measurement signal S meas,i The corrected signal S is corrected by the following formula corr,i , in D1 is the initial background signal level, D2 is the background signal level used to determine the correction function, and D meas,i is the measurement signal S meas,i The background signal level, S ref,1 is the first reference signal with background level D1, S ref,2 is a second reference signal with a background level D2.

12. A non-transitory computer readable medium comprising instructions which, when executed by one or more processors, cause the one or more processors to perform at least one of the methods according to any of the preceding method claims.

13. A photodetector (120) for measuring optical radiation (112), the photodetector (120) being configured to perform a method for determining at least one correction function for compensating for changes in the responsivity of at least one photodetector (120) according to any of the preceding claims relating to a method for determining at least one correction function for compensating for changes in the responsivity of at least one photodetector (120), and / or to perform a method for determining at least one item of information about a measurement object (114) according to any of the preceding claims relating to a method for determining at least one item of information about a measurement object (114), wherein: The photodetector (120) includes at least one photosensitive region (122) and at least one readout electronics unit (124).

14. A spectrometer (110) for spectrally analyzing optical radiation (112) provided by at least one measurement object (114), the spectrometer comprising: at least one radiation source (116) configured to emit optical radiation at least partially towards the measurement object (114); as well as - At least one photodetector (120) according to the preceding claim.

15. Use of the spectrometer (110) according to the preceding claim for a purpose of use selected from the group consisting of: infrared detection applications; thermal detection applications; thermometer applications; heat seeking applications; flame detection applications; fire detection applications; smoke detection applications; temperature sensing applications; spectroscopy applications; exhaust gas monitoring applications; combustion process monitoring applications; pollution monitoring applications; industrial process monitoring applications; chemical process monitoring applications; food processing process monitoring applications; water quality monitoring applications; air quality monitoring applications; quality control applications; temperature control applications; motion control applications; emission control applications; gas sensing applications; gas analysis applications; motion sensing applications; chemical sensing applications; mobile applications; medical applications; mobile spectroscopy applications; food analysis applications.

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