Method for calibrating a spectrometer device

Abstract

A method is disclosed for calibrating a spectrometer device (114), the spectrometer device (114) comprising at least one detector device (112) comprising at least one optical element (116) configured to separate incident light into a spectrum of constituent wavelength components, and further comprising a plurality of photosensitive elements (122), each photosensitive element (124) configured to receive at least a portion of one of the constituent wavelength components and generate a respective detector signal in response to illumination of the respective photosensitive element (124) by at least one portion of each of the constituent wavelength components. The method comprises the following steps: a) illuminating a spectrometer arrangement (114), in particular a detector arrangement (112), via at least one optical interferometer (130) using at least one broadband light source (128); b) determining for the plurality of photosensitive elements (122), in particular for each of the photosensitive elements (124), a plurality of detector signals in response to illumination via the optical interferometer (130) in step a); and c) determining at least one item of calibration information from the plurality of detector signals. Includes. Further disclosed is a system (110) for calibrating a spectrometer device (114), a computer program and a computer readable storage medium for carrying out the method.

Description

[Technical field]

[0001] The present invention relates to a method and a system for calibrating a spectrometer device. Furthermore, the present invention relates to a computer program and a computer readable storage medium for carrying out the method for calibrating a spectrometer device. The method and device of the present invention can be used in particular for calibrating a spectrometer device used for investigations in the infrared spectral range, in particular in the near infrared and mid infrared spectral ranges. However, other spectrometer devices used for optical investigations are also feasible. [Background technology]

[0002] Spectroscopy is widely used in research, industrial and customer applications, enabling multiple applications such as optical analysis and / or quality control. It is used in food, agriculture, pharmaceutical, medical, life sciences and many other fields. Various methods are available, such as photometry, absorption, fluorescence and Raman spectroscopy, allowing qualitative and / or quantitative analysis of samples. These methods usually involve mapping spectral information, such as the irradiance of a sample at a particular wavelength, to a specific physical section of the spectroscopic device, e.g. a detector pixel, a time interval, etc.

[0003] In general, spectroscopy requires reliable performance of the spectroscopic instruments with negligible variation for successful applications, especially when measurements from different spectroscopic instruments are compared with each other. Specifically, the spectral data of a particular sample should be at least similar or identical for different spectroscopic instruments of the same type.

[0004] In spectroscopic devices, wavelength and / or stray light calibration is generally crucial for reliable performance. In particular, some spectroscopic devices use gratings and / or filters, such as bandpass filters, as part of the optical sensor to select which parts of the spectrum are detected by a particular detector element. Detailed information of the grating and / or filter, such as bandwidth and / or bandstop, and its interaction with the detector elements may generally be required to understand the response of the optical sensor. For example, when an optical sensor is constructed by placing a linear variable filter on a linear array of multiple detector elements or pixels, wavelength calibration of the optical sensor may generally be required.

[0005] Various methods for wavelength calibration and / or stray light calibration are known in the art. For example, an optical sensor can be illuminated with monochromatic light of a certain wavelength. This illumination light is detected by certain detector elements of a linear array. Since the wavelength of the monochromatic light is known, the optical sensor can be calibrated. Furthermore, information about the spectral resolution of the optical sensor can be obtained in this way.

[0006] As an example, a method for correcting the response of a spectroradiometer for measurement errors resulting from instrument spectral stray light is described in Y. Zong, SW Brown, BC Johnson, KR Lykke and Y. Ohno: "Simple spectral stray light correction method for array spectroradiometers", Applied Optics, Vol. 45, No. 6, 2006. By characterizing the response of the instrument to a set of monochromatic laser sources that cover the spectral range of the instrument, a spectral stray light signal distribution matrix is ​​obtained that quantifies the magnitude of the spectral stray light signal in the instrument. Using these data, a spectral stray light correction matrix can be derived to correct the instrument response with a simple matrix multiplication.

[0007] US2011 / 032529A1 discloses the calibration of any spectrometer using a stable monolithic interferometer as a wavelength calibration standard. Light from a polychromatic light source is input to the monolithic interferometer and is subjected to interference based on the optical path difference of the interferometer. The resulting wavelength modulated output beam is analyzed in a reference spectrometer to generate reference data. The output beam from the interferometer can be fed to any spectral instrument. Wavelength calibration of the any spectral instrument is based on a comparison of the spectral instrument output to the reference data.

[0008] WO2003 / 085371A2 discloses a method and system for real-time high-speed high-resolution hyperspectral imaging. The system comprises an electromagnetic radiation collimating element for collimating electromagnetic radiation emitted by an object in a scene or sample. The system comprises an optical interferometer for receiving and splitting the collimated object radiation beam, generating an interference image, and piezoelectrically determining and modifying the magnitude of the optical path difference of the split collimated object radiation beam. The optical interferometer includes a beam splitter, a fixed mirror, a movable mirror, a piezoelectric motor for displacing the movable mirror along an axis, a distance change feedback sensor for sensing and measuring the change in distance of the movable mirror along the axis, a piezoelectric motor controller for actuating and controlling the piezoelectric motor, and a thermomechanically stable optical interferometer mount. The system further comprises camera optics for collecting an interference image of each optical path difference, a detector for recording the interference image, a central programming and signal processing unit, and a display.

[0009] Despite the advantages achieved by known methods and devices, some technical challenges remain. In particular, each wavelength may have to be calibrated separately. Such a procedure may be time-consuming and costly, since it requires monochromatic light of different wavelengths. Alternatively, it may be possible to use only a few wavelengths for calibration and to interpolate the signals of the detector elements in between. However, the interpolation may limit the amount of information that can be obtained with the optical sensor. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] US2011 / 032529A1 [Patent Document 2] WO2003 / 085371A2 [Non-patent literature]

[0011] [Non-Patent Document 1] Y. Zong, S.W. Brown, B.C. Johnson, K.R. Lykke and Y. Ohno: "Simple spectral stray light correction method for array spectroradiometers", Applied Optics, Vol. 45, No. 6, 2006. Summary of the Invention [Problem to be solved by the invention]

[0012] It would therefore be desirable to provide an apparatus that at least partially addresses the above technical challenges related to calibrating a spectrometer device. In particular, a method and system for calibrating a spectrometer device is proposed that increases the amount of calibration information while providing time- and cost-effective calibration. [Means for solving the problem]

[0013] This problem is addressed by a method and a system for calibrating a spectrometer device, by a computer program and a computer readable storage medium with the features of the independent claims. Advantageous embodiments, which may be realized independently or in any combination, are set out in the dependent claims and in the specification as a whole.

[0014] The terms "having", "comprises" or "including" as used herein, or any grammatical variants thereof, are used in a non-exclusive manner. Thus, these terms can refer both to the situation where, apart from the features introduced by these terms, no further features are present in the entity described in this context, and to the situation where one or more further features are present. As an example, the expressions "A has B", "A comprises B" and "A includes B" can refer both to the situation where no other elements are present in A apart from B (i.e., A solely and exclusively comprises B), and to the situation where, in addition to B, one or more further elements are present in entity A, such as element C, elements C and D, or further elements.

[0015] Additionally, it should be noted that the terms "at least one," "one or more," or similar language indicating that a feature or element may be present more than one time, are typically used only once when introducing each feature or element. In most cases, when referring to each feature or element, the language "at least one" or "one or more" will not be repeated, despite the fact that each feature or element may be present more than one time.

[0016] Furthermore, as used herein, the terms "preferably", "more preferably", "particularly", "more particularly", "particularly", "more particularly", or similar terms are used in connection with any feature without limiting the possibility of substitution. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. The invention can be practiced with alternative features, as will be recognized by those skilled in the art. Similarly, features introduced by "in one embodiment of the invention" or similar expressions are intended to be optional features, without any limitation on alternative embodiments of the invention, without any limitation on the scope of the invention, and without any limitation on the possibility of combining the feature introduced in such a way with other optional or non-optional features of the invention.

[0017] In a first aspect of the present invention, a method for calibrating a spectrometer device, such as a detector of a spectrometer device, is disclosed.

[0018] The term "spectrometer device" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically, but not limited to, refer to a device capable of optically analyzing at least one sample and thereby generating at least one item of information regarding at least one spectral characteristic of the sample. In particular, the term can refer to a device capable of recording signal intensity with respect to a corresponding wavelength or a section thereof, e.g., a wavelength interval, of a spectrum, the signal intensity preferably being provided as an electrical signal that can be used for further evaluation. The optical element can specifically comprise at least one wavelength-selective element, such as an optical filter and / or a dispersive element, and can be used to separate the incident light into a spectrum of constituent wavelength components whose respective intensities are determined by using a detector device. In addition, additional optical elements may be used that can be designed to receive the incident light and transmit the incident light to the optical element. The spectrometer device can generally be operable in a reflection mode and / or a transmission mode. For possible embodiments of the spectrometer device, please refer to the description of the spectrometer device outlined in more detail below.

[0019] The term "calibrate" (this process is also referred to as "calibration") as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically refer to, but is not limited to, at least one process of determining, correcting and adjusting measurement inaccuracies in a spectrometer device. Thus, the result of the calibration process, often also referred to as an "item of calibration information", is or may comprise at least one item of information about the result of the calibration process, such as, for example, a calibration function, a calibration coefficient, a calibration matrix, etc., for converting one or more measured values ​​into one or more calibrated or "true" values. The measurement inaccuracies may result from, by way of example, uncertainties in wavelength determination and / or inherent and / or external interferences to the measurement signal of the spectrometer device. Thus, the calibration of the spectrometer device may comprise at least one of wavelength calibration, stray light calibration, dark current calibration, and testing of spectral resolution. The calibrations, and in particular each calibration, may comprise at least one two-stage process, where in a first step information about the deviation of the measurement signal of the spectrometer device from a known standard is determined, and in a second step this information is used to correct and / or adjust the measurement signal of the spectrometer device to reduce, minimize and / or eliminate the deviation. Thus, a calibration may comprise applying an item of calibration information to, for example, the measurement signal and / or the measurement spectrum of the spectrometer device. Calibration of the spectrometer device may improve and / or maintain the accuracy of measurements performed with the calibrated spectrometer device.

[0020] Calibration of the spectrometer device may in particular be performed at the manufacturer's site by the spectrometer device manufacturer, however calibration may also be performed in the field, for example after setup of the spectrometer device at the site of use and / or for maintenance purposes.

[0021] The spectrometer device comprises at least one detector device. Thus, specifically, when calibrating the spectrometer device, calibration of the detector device that the spectrometer device comprises may be necessary and may be performed. The term "detector device" is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically refer to, but is not limited to, any device or combination of devices that can record and / or monitor incident light. The detector device may be configured to respond to incident illumination and generate an electrical signal indicative of the intensity of the illumination. The detector device may have sensitivity in one or more of the visible, ultraviolet, or infrared spectral ranges, specifically the near-infrared spectral range (NIR). The detector device may specifically be or comprise at least one optical sensor, for example an optical semiconductor sensor. As an example, particularly when the detector device has sensitivity in the infrared spectral range, such as the near-infrared spectral range, the semiconductor sensor may be or may comprise at least one semiconductor sensor including at least one material selected from the group consisting of Si, PbS, PbSe, InGaAs, and extended InGaAs. As an example, the detector device may comprise at least one photodetector, such as at least one CCD or CMOS device. The detector device may specifically comprise at least one detector array including a plurality of pixelated sensors, each of which is configured to detect at least a portion of at least one of the constituent wavelength components.

[0022] The detector device comprises at least one optical element configured to separate the incident light into a spectrum of constituent wavelength components. The term "optical element" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically refer to any element or combination of elements suitable for one or more of transmitting, reflecting, deflecting, or scattering light in a wavelength-dependent manner, but is not limited thereto. The optical element can further be specifically configured to separate the incident light into a spectrum of constituent wavelength components and then transmit the spectrum onto the detector device. Specifically, the wavelength-dependent transmission, reflection, deflection, or scattering of the incident light in the optical element results in a spatial separation of the constituent wavelength components of the spectrum, which can then be transmitted directly or indirectly onto the detector device.

[0023] The term "light" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to any special or customized meaning. The term can specifically refer to, but is not limited to, the section of electromagnetic radiation that is usually referred to as the "optical spectrum range" and includes one or more of the visible spectrum range, the ultraviolet spectrum range, and the infrared spectrum range. The term "ultraviolet spectrum" or "UV" generally refers to electromagnetic radiation having wavelengths between 1 nm and 380 nm, preferably between 100 nm and 380 nm. The term "visible" generally refers to wavelengths between 380 nm and 760 nm. The term "infrared" or "IR" generally refers to wavelengths between 760 nm and 1000 μm, with wavelengths between 760 nm and 3 μm usually referred to as "near infrared" or "NIR", while wavelengths between 3 μm and 15 μm are usually designated as "mid infrared" or "MidIR", and wavelengths between 15 μm and 1000 μm are usually designated as "far infrared" or "FIR".

[0024] The term "spectrum" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically, but not limited to, refer to a section of the optical spectrum range interrogated by a spectrometer device, specifically, at least one of the IR spectrum range, especially the NIR or MidIR spectrum range. Each portion of the spectrum may be constituted by an optical signal defined by a signal wavelength and a corresponding signal intensity. Thus, the term "constituent wavelength components" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically, but not limited to, refer to an optical signal forming a portion of the spectrum. Specifically, the optical signal may include a signal intensity corresponding to each wavelength or wavelength interval.

[0025] The detector apparatus further comprises a plurality of photosensitive elements, each photosensitive element configured to receive at least a portion of one of the constituent wavelength components and to generate a respective detector signal in response to illumination of the respective photosensitive element by at least a portion of each of the constituent wavelength components.

[0026] The term "photosensitive element" as used herein is a broad term and should be given its normal and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. This term can specifically, but not exclusively, refer to individual optical sensors comprised by a detector device, each optical sensor having at least one photosensitive area, which is configured to record the optical response of the photosensitive element by generating at least one output signal that depends on the intensity of a portion of one of the constituent wavelength components incident on the particular photosensitive area. The at least one photosensitive area comprised by an individual optical sensor may be a single homogeneous area specifically designed to receive the incident light that is incident on the photosensitive area. The at least one output signal can specifically be used as a detector signal and preferably be provided to an external evaluation unit for further evaluation.

[0027] The term "detector signal" is therefore a broad term and should be given its ordinary and customary meaning by those skilled in the art and should not be limited to a special or customized meaning. The term can specifically, but not exclusively, refer to a signal generated by at least one detector, specifically at least one output signal of a photosensitive element. The at least one output signal may be selected from at least one of an electronic signal and an optical signal. The at least one output signal may be an analog signal and / or a digital signal. The output signals of adjacent photosensitive elements can be generated simultaneously or successively in time. For example, during a row scan or a line scan, a sequence of output signals corresponding to a series of photosensitive elements arranged in a column can be generated. Furthermore, each photosensitive element may preferably be an active pixel sensor, which may be adapted to amplify the output signal before providing it as a detector signal to an external evaluation unit. For this purpose, the photosensitive element may comprise one or more signal processing devices, such as one or more filters and / or analog-to-digital converters for processing and / or pre-processing the electronic signal.

[0028] The present invention includes the following steps, which are performed in the given order by way of example. However, it should be noted that different orders are possible. Furthermore, one or more of the method steps may be performed once or repeatedly. Furthermore, two or more of the method steps may be performed simultaneously or overlapping in time. The method may include further method steps not listed.

[0029] This method involves the following steps: a) illuminating a spectrometer arrangement, in particular a detector arrangement, using at least one broadband light source via at least one optical interferometer; b) determining for the plurality of photosensitive elements, in particular for each of the photosensitive elements, a plurality of detector signals in response to the illumination via the optical interferometer in step a); and c) determining at least one item of calibration information from the plurality of detector signals. Includes.

[0030] The term "illuminate" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically refer to, but is not limited to, the process of providing, passing, and / or directing light from a light source to a device or element to be illuminated. Specifically, illuminating a device or element using a broadband light source may include providing and / or directing light emitted from the broadband light source to the device or element to be illuminated. One or more additional devices may be disposed on the path of light from the broadband light source to the device or element to be illuminated. Thus, illuminating a device or element to be illuminated through one or more additional devices may include directing light from the broadband light source to one or more additional devices and then providing and / or directing the light to the device or element to be illuminated. For example, illuminating a spectrometer device, specifically a detector device, through an optical interferometer may include directing light from the broadband light source to an optical interferometer and then directing the light that has passed through the optical interferometer to a spectrometer device, specifically a detector device.

[0031] The term "broadband light source" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically refer to a device that emits light in a broad spectral range, such as, but not limited to, light having a spectral width of at least 5 nm, specifically at least 10 nm, for example, a spectral width of 10 nm to 3000 nm. The broad spectral range of the broadband light source may include at least one of the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The light used for the exemplary purpose of the present invention may include, in particular, light having a wavelength in at least one of the IR spectral range, specifically the NIR or MidIR spectral range, more specifically 1 μm to 5 μm, and even more specifically 1 μm to 3 μm. For example, the broadband light source may comprise a thermal emitter that emits light in the NIR and MidIR, such as 1000 nm to 3000 nm, more specifically 1300 nm to 2500 nm. Further possible embodiments of the broadband light source are described in more detail below.

[0032] The term "optical interferometer" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to any special or customized meaning. The term can specifically, but not exclusively, refer to a device or combination of devices that allows superposition of light, specifically superposition of light in the optical spectrum range, and causes the effect of interference of the superposed light. For example, the optical interferometer can be configured to split incident light into at least two light beams and further cause a phase shift of the split light beams relative to each other. The optical interferometer can further be configured to combine the phase-shifted light beams such that the light beams are superposed and interfere with each other.

[0033] The optical interferometer may in particular be selected from the group consisting of a Michelson interferometer, a Fabry-Perot interferometer, and a cube-corner interferometer, although other optical interferometers are also feasible.

[0034] Further, in step a), the transmission frequency of the optical interferometer may be varied over a predetermined spectral range, and in step b), a plurality of detector signals may be determined in response to the transmission frequency of the optical interferometer. In step c), at least one item of calibration information may be determined by comparing the transmission frequency of the optical interferometer with at least one of the pixel positions and identification numbers of the plurality of photosensitive elements that generate intensity peaks of the plurality of detector signals associated with the transmission frequency. The term "transmission frequency" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically, but is not limited to, a dominant frequency in a spectrum of a plurality of frequencies transmitted through an optical spectrometer. In particular, the transmission frequency of the optical interferometer may refer to a dominant frequency in a spectrum of transmission frequencies having the highest transmission intensity. The transmission frequency may be used as a reference for calibrating the optical interferometer. The term "pixel position" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically, but is not limited to, refer to any item of position information of a photosensitive element in a detector device. The pixel information represents the position of the photosensitive element in the detector device, specifically, in one dimension, two dimensions, or even three dimensions, by using one or more of absolute position information and relative position information. The term "identification number" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can specifically, but is not limited to, refer to a numeric or alphanumeric item of information that uniquely identifies each photosensitive element that the detector device comprises. For example, the photosensitive elements of the detector device may be numbered with respect to the order of their appearance in the detector device. However, other options for identifying the photosensitive elements of the detector device are also feasible.

[0035] The multiple detector signals may be recorded for wavenumbers in the range of 12.000 1 / cm to 500 1 / cm, particularly in the range of 10.000 1 / cm to 1000 1 / cm, and more particularly in the range of 7.000 1 / cm to 4.000 1 / cm. Thus, the optical spectrometer device may be configured to transmit light having wavenumbers in the range of 12.000 1 / cm to 500 1 / cm, particularly in the range of 10.000 1 / cm to 1000 1 / cm, and more particularly in the range of 7.000 1 / cm to 4.000 1 / cm.

[0036] The optical interferometer may, for example, comprise at least one beam splitting device for splitting the incident light, in particular the incident light from a broadband light source, into at least two illumination paths. The optical interferometer may further comprise at least one scanning mirror in the first illumination path and at least one stationary mirror in the second illumination path. In the method, in particular in step a), the scanning mirror may be moved along the first illumination path and the stationary mirror may remain stationary. The scanning mirror may be moved stepwise with a step frequency of 1 kHz or less, in particular with a step frequency of 500 Hz or less, more particularly with a step frequency of 150 Hz or less. In particular, the step frequency of the scanning mirror may be slower than the maximum readout frequency of the detector device. For example, if the maximum readout frequency of the detector device limits the stepping frequency to 1 kHz or less, a stepping frequency of 100 Hz is optimal. The term "readout frequency" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically, but not limited to, refer to a quantitative measure of readouts performed at a particular time interval. Specifically, in a detector device, the output signal of the photosensitive element may be generated by an associated signal processing device, such as a readout integrated circuit. For example, each photosensitive element may include a readout integrated circuit, which may be configured to accumulate the photoresponse, specifically the photocurrent, of the photosensitive element generated in response to illumination of the photosensitive element, and to transmit the accumulated photoresponse for further signal processing. The readout frequency may indicate the time interval during which the photocurrent of the photosensitive element is accumulated by the readout integrated circuit. The term "stepping frequency" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term may specifically, but not limited to, refer to a quantitative measure of steps performed at a particular time interval. Specifically, the step frequency of the scanning mirror may quantify the number of steps or positions of the scanning mirror in the first illumination path per second.

[0037] Furthermore, in step b), the multiple detector signals may be determined for multiple positions of the scanning mirror in the first illumination path. The multiple positions of the scanning mirror may be different from one another. Furthermore, step c) may specifically include correlating the multiple detector signals with the multiple positions of the scanning mirror prior to processing the multiple detector signals. Thus, in step c), the multiple detector signals correlated to the multiple positions of the scanning mirror may be used to determine at least one item of calibration information.

[0038] Additionally or alternatively, step c) may include processing the plurality of detector signals determined in step b), thereby obtaining a plurality of processed detector signals. The determination of at least one item of calibration information in step c) may include determining at least one item of calibration information from the plurality of processed detector signals. The term "processing" as used herein may specifically refer to a process of performing one or more operations on the plurality of detector signals. The result of the processing may be or may include a plurality of processed detector signals. Specifically, the processing of the plurality of detector signals may include transforming, specifically mathematically transforming, the plurality of detector signals. For example, the plurality of detector signals may be transformed using at least one Fourier transform, specifically at least one discrete Fourier transform. Additionally or alternatively, the processing may include applying one or more of an offset correction and a digital filter to the plurality of detector signals.

[0039] As outlined above, step c) comprises determining at least one item of calibration information. The item of calibration information may comprise at least one of an item of wavelength calibration information and an item of stray light calibration information. The item of wavelength calibration information may comprise at least one wavelength calibration function. The wavelength calibration function may assign at least one of the pixel positions and the identification number of the photosensitive element to the wavelength positions. For example, the wavelength calibration function may comprise a polynomial function. However, other wavelength calibration functions are also feasible. The item of stray light calibration information may comprise at least one signal distribution function, in particular at least one signal distribution matrix. The signal distribution function represents the distribution of responses of a plurality of photosensitive elements, in particular the distribution of the response of each photosensitive element, to incident light having a particular wavelength. By way of example, the calculation and / or application of the signal distribution matrix is ​​described in further detail in Y. Zong, SW Brown, BC Johnson, KR Lykke and Y. Ohno: "Simple spectral stray light correction method for array spectroradiometers", Applied Optics, Vol. 45, No. 6, 2006.

[0040] Additionally or alternatively, the method, and in particular step c), may be at least partially computer-implemented, as outlined in more detail below.

[0041] In a further aspect of the invention, a system for calibrating a spectrometer device is disclosed, comprising a spectrometer device with at least one detector device, the detector device comprising at least one optical element configured to separate incident light into a spectrum of constituent wavelength components, and further comprising a plurality of light-sensitive elements, each light-sensitive element configured to receive at least a portion of one of the constituent wavelength components and generate a respective detector signal in response to illumination of the respective light-sensitive element by at least one portion of each of the constituent wavelength components. The system further comprises at least one broadband light source and at least one optical interferometer arranged to illuminate the spectrometer device, in particular the detector device, with the broadband light source via the optical interferometer. The system further comprises at least one evaluation unit, the evaluation unit configured to perform a method according to the invention, for example according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below.

[0042] For definitions and possible embodiments of the system or parts thereof, reference is made to the definitions and embodiments explained with respect to the method for calibrating a spectrometer device.

[0043] The term "evaluation unit" as used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art and should not be limited to a special or customized meaning. The term can refer specifically, but not limited to, any logic circuit configured to perform the basic operations of a computer or system, and / or generally, a device configured to perform calculations or logical operations. In particular, the evaluation unit can be configured to process basic instructions that run a computer or system. As an example, the evaluation unit may be composed of at least one arithmetic logic unit (ALU), at least one floating point unit (FPU), such as a math coprocessor or numeric coprocessor, a number of registers, specifically, registers configured to provide operands to the ALU and store operation results, and memories, such as an L1 cache memory and an L2 cache memory. In particular, the processor may be a multi-core processor. In particular, the evaluation unit may be or comprise a central processing unit (CPU). For example, the evaluation unit may comprise one or more processors. Additionally or alternatively, the evaluation unit may be or comprise a microprocessor, so that in particular the elements of the evaluation unit may be contained in one integrated circuit (IC) chip. Additionally or alternatively, the evaluation unit may be or comprise one or more chips, such as one or more application specific integrated circuits (ASICs) and / or one or more field programmable gate arrays (FPGAs) and / or one or more tensor processing units (TPUs) and / or a dedicated machine learning optimization chip. The evaluation unit may be configured, such as by software programming, in particular to perform one or more evaluation operations, in particular one or more operations performed in step c) of the method described in more detail above. The evaluation unit may be configured to exchange data and / or control commands, in one direction and / or in two directions, with other elements of the system, in particular the detector device. In particular, the evaluation unit may be configured to receive a plurality of detector signals from the detector device.

[0044] The broadband light source may comprise, by way of example only, at least one of an incandescent lamp, a black body radiator, an electric filament, and a light emitting diode.

[0045] The optical element may comprise at least one wavelength selective element, which may be selected from the group consisting of a prism, a diffraction grating, a linear tunable filter, an optical filter, in particular a narrow bandpass filter.

[0046] The detector device may comprise a number of photosensitive elements arranged in a linear array. The linear array of photosensitive elements may comprise a number of 10 to 1000 photosensitive elements, in particular a number of 100 to 500 photosensitive elements, in particular a number of 200 to 300 photosensitive elements, more particularly a number of 256 photosensitive elements. Each photosensitive element may be selected from the group consisting of a pixelated inorganic camera element, in particular a pixelated inorganic camera chip, more particularly a CCD chip or a CMOS chip, a monochrome camera element, in particular a monochrome camera chip, at least one photoconductor, in particular an inorganic photoconductor, more particularly an inorganic photoconductor comprising PbS, PbSe, Ge, InGaAs, ext.InGaAs, InSb or HgCdTe. Each photosensitive element can be sensitive to electromagnetic radiation in the wavelength range of 760 nm to 1000 μm, specifically in the wavelength range of 760 nm to 15 μm, more specifically in the wavelength range of 1 μm to 5 μm, and even more specifically in the wavelength range of 1 μm to 3 μm.

[0047] The detector arrangement may in particular be provided in a spectrometer arrangement, in particular in at least one of a reflectance spectrometer arrangement and a transmission spectrometer arrangement.

[0048] In a further aspect of the present invention, a computer program is disclosed comprising instructions which, when executed by a system according to the present invention, e.g. according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below, cause an evaluation unit of the system to perform a method for calibrating a spectrometer device according to the present invention, e.g. according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below.

[0049] Thus, in particular, at least the method step c) indicated above may be performed by using a computer or a computer network, preferably by using a computer program, however, one, more than one or even all of the method steps a) to c) indicated above may at least be computer controlled and / or supported by a computer or a computer network.

[0050] In a further aspect of the present invention, a computer readable storage medium is disclosed which comprises instructions which, when executed by a system according to the present invention, e.g. according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below, cause an evaluation unit of the system to perform a method for calibrating a spectrometer device according to the present invention, e.g. according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below.

[0051] The term "computer-readable storage medium" as used herein may specifically refer to a non-transitory data storage means such as a hardware storage medium on which computer-executable instructions are stored. A computer-readable storage medium may also be called a computer-readable data carrier, and may specifically be or comprise a storage medium such as a random access memory (RAM) and / or a read-only memory (ROM).

[0052] The method and system according to the invention may offer a number of advantages over known methods and devices. In particular, by combining a spectrometer device, in particular a spectrometer device with a detector device having a linear variable filter as an optical element, with an optical interferometer, the calibration of the spectrometer device may be improved. The method and system allow for a faster calibration of the spectrometer device while increasing the amount of measurement information, such as information on the spectral resolution and stray light. In particular, the need to calibrate each wavelength individually with a monochromatic laser source and / or several different bandpass filters may be eliminated by carrying out the method according to the invention.

[0053] In this method, broadband light may be emitted from a broadband light source, pass through an optical interferometer, and be directed to a spectrometer arrangement, in particular a detector arrangement. The light-sensitive elements of the detector arrangement, in particular all of the light-sensitive elements, may be read out using suitable electronics. The detector signals as a function of time I(t) may be correlated to the movement of a scanning mirror in the optical interferometer. Using a Fourier transform, the total transmission spectrum of the optical element is obtained for each light-sensitive element provided in the detector arrangement.

[0054] By way of summary and without excluding further possible embodiments, the following embodiments can be envisaged:

[0055] Embodiment 1: A method for calibrating a spectrometer device, the spectrometer device comprising at least one detector device, the detector device comprising at least one optical element configured to separate incident light into a spectrum of constituent wavelength components, and further comprising a plurality of photosensitive elements, each photosensitive element configured to receive at least a portion of one of the constituent wavelength components and generate a respective detector signal in response to illumination of the respective photosensitive element by at least one portion of each of the constituent wavelength components; Follow these steps: a) illuminating a spectrometer arrangement, in particular a detector arrangement, using at least one broadband light source via at least one optical interferometer; b) determining for the plurality of photosensitive elements, in particular for each of the photosensitive elements, a plurality of detector signals in response to the illumination via the optical interferometer in step a); and c) determining at least one item of calibration information from the plurality of detector signals. A method comprising:

[0056] Embodiment 2: The method of the preceding embodiment, wherein the optical interferometer is selected from the group consisting of a Michelson interferometer, a Fabry-Perot interferometer, and a cube-corner interferometer.

[0057] Embodiment 3: A method according to any one of the preceding embodiments, wherein in step a), the transmission frequency of the optical interferometer is varied over a predetermined spectral range, and in step b), a plurality of detector signals are determined according to the transmission frequency of the optical interferometer.

[0058] Embodiment 4: A method as described in the preceding embodiment, wherein in step c) at least one item of calibration information is determined by comparing a transmission frequency of the optical interferometer with at least one of pixel positions and identification numbers of a plurality of photosensitive elements producing intensity peaks of a plurality of detector signals associated with the transmission frequency.

[0059] Embodiment 5: A method according to any one of the preceding embodiments, wherein the optical interferometer comprises at least one beam splitting device for splitting incident light, particularly incident light from a broadband light source, into at least two illumination paths, and the optical interferometer further comprises at least one scanning mirror in a first illumination path and at least one stationary mirror in a second illumination path, and in the method, particularly in step a), the scanning mirror is moved along the first illumination path and the stationary mirror remains stationary.

[0060] Embodiment 6: The method according to the preceding embodiment, wherein the scanning mirror is moved stepwise with a step frequency of 1 kHz or less, in particular with a step frequency of 500 Hz or less, more particularly with a step frequency of 150 Hz or less.

[0061] Embodiment 7: A method according to any one of the two preceding embodiments, wherein in step b), a plurality of detector signals are determined for a plurality of positions of the scanning mirror in the first illumination path, the plurality of positions of the scanning mirror being different from each other.

[0062] Embodiment 8: The method of the preceding embodiment, wherein step c) specifically comprises correlating the multiple detector signals with multiple positions of the scanning mirror before processing the multiple detector signals.

[0063] Embodiment 9: The method of the preceding embodiment, wherein in step c), a plurality of detector signals correlated to a plurality of positions of the scanning mirror are used to determine at least one item of calibration information.

[0064] Embodiment 10: A method according to any one of the preceding embodiments, wherein step c) comprises processing the plurality of detector signals determined in step b), thereby obtaining a plurality of processed detector signals, and wherein determining at least one item of calibration information in step c) comprises determining at least one item of calibration information from the plurality of processed detector signals.

[0065] Embodiment 11: The method according to the preceding embodiment, wherein processing the plurality of detector signals comprises transforming, in particular mathematically transforming, the plurality of detector signals.

[0066] Embodiment 12: The method according to the preceding embodiment, wherein the plurality of detector signals are transformed using at least one Fourier transform, in particular at least one discrete Fourier transform.

[0067] Embodiment 13: The method of any one of the preceding embodiments, wherein the detector signals are recorded for wavenumbers in the range of 12,000 1 / cm to 500 1 / cm, specifically in the range of 10,000 1 / cm to 1000 1 / cm, more specifically in the range of 7,000 1 / cm to 4,000 1 / cm.

[0068] Embodiment 14: A method according to any one of the preceding embodiments, wherein the items of calibration information include at least one of an item of wavelength calibration information and an item of stray light calibration information.

[0069] Embodiment 15: The method according to the preceding embodiment, wherein the item of wavelength calibration information includes at least one wavelength calibration function, the wavelength calibration function assigning at least one of a pixel position and an identification number of the photosensitive element to a wavelength position.

[0070] Embodiment 16: A method according to any one of the preceding two embodiments, wherein the item of stray light calibration information includes at least one signal distribution function, in particular at least one signal distribution matrix, the signal distribution function representing the distribution of responses of a plurality of photosensitive elements to incident light having a particular wavelength, in particular the distribution of the response of each photosensitive element.

[0071] Embodiment 17: A method according to any one of the preceding embodiments, in particular where step c) is at least partially computer-implemented.

[0072] Embodiment 18: A system for calibrating a spectrometer device, comprising: a spectrometer device with at least one detector device, the detector device comprising at least one optical element configured to separate incident light into a spectrum of constituent wavelength components, and further comprising a plurality of photosensitive elements, each photosensitive element configured to receive at least a portion of one of the constituent wavelength components and generate a respective detector signal in response to illumination of the respective photosensitive element by at least one portion of each of the constituent wavelength components, the system further comprising at least one broadband light source and at least one optical interferometer arranged to illuminate the spectrometer device, in particular the detector device, with the broadband light source via an optical interferometer, the system further comprising at least one evaluation unit, the evaluation unit configured to perform the method according to any one of the preceding embodiments.

[0073] Embodiment 19: The system of the preceding embodiment, wherein the broadband light source comprises at least one of an incandescent lamp, a blackbody radiator, an electric filament, and a light emitting diode.

[0074] Embodiment 20: A system described in any one of the previous two embodiments, wherein the optical element comprises at least one wavelength-selective element.

[0075] Embodiment 21: The system according to the preceding embodiment, wherein the wavelength-selective element is selected from the group consisting of a prism, a diffraction grating, a linear tunable filter, and an optical filter, specifically a narrow bandpass filter.

[0076] Embodiment 22: A system described in any one of the preceding four embodiments, wherein the detector device comprises a plurality of photosensitive elements arranged in a linear array, and the linear array of photosensitive elements comprises a number of 10 to 1000 photosensitive elements, particularly a number of 100 to 500 photosensitive elements, particularly a number of 200 to 300 photosensitive elements, more particularly a number of 256 photosensitive elements.

[0077] Embodiment 23: A system described in any one of the preceding five embodiments, wherein each photosensitive element is selected from the group consisting of a pixelated inorganic camera element, specifically a pixelated inorganic camera chip, more specifically a CCD chip or a CMOS chip, a monochrome camera element, specifically a monochrome camera chip, at least one photoconductor, specifically an inorganic photoconductor, more specifically an inorganic photoconductor comprising PbS, PbSe, Ge, InGaAs, ext.InGaAs, InSb or HgCdTe.

[0078] Embodiment 24: A system described in any one of the preceding six embodiments, wherein each photosensitive element is sensitive to electromagnetic radiation in the wavelength range of 760 nm to 1000 μm, specifically in the wavelength range of 760 nm to 15 μm, more specifically in the wavelength range of 1 μm to 5 μm, and more specifically in the wavelength range of 1 μm to 3 μm.

[0079] Embodiment 25: A system described in any one of the preceding seven embodiments, wherein the detector device is provided in a spectrometer device, specifically at least one of a reflectance spectrometer device and a transmission spectrometer device.

[0080] Embodiment 26: A computer program comprising instructions that, when executed by a system described in any one of the preceding system-related embodiments, cause an evaluation unit of the system to perform a method for calibrating a spectrometer device described in any one of the preceding method-related embodiments.

[0081] Embodiment 27: A computer-readable storage medium comprising instructions which, when executed by a system described in any one of the embodiments relating to the preceding systems, cause an evaluation unit of the system to perform a method for calibrating a spectrometer device described in any one of the embodiments relating to the preceding methods. [Brief description of the drawings]

[0082] Further optional features and characteristics are preferably disclosed in more detail in the following description of the embodiments in conjunction with the dependent claims. Here, it will be understood by those skilled in the art that each optional feature may be implemented individually and also in combination with any optional feature. The scope of the present invention is not limited to the preferred embodiments. The embodiments are illustrated diagrammatically in the figures. The same reference numbers in these figures refer to identical or functionally equivalent elements.

[0083] In the diagram below: [Figure 1] FIG. 1 shows in a schematic diagram an embodiment of a system for calibrating a spectrometer device. [Diagram 2] FIG. 2 shows a flow chart of an embodiment of a method for calibrating a spectrometer device. [Diagram 3] 3A-3D are diagrams of stray light calibration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0084] 1 shows in a schematic diagram an exemplary embodiment of a system 110 for calibrating a spectrometer device 114. The system 110 includes a spectrometer device 114 with at least one detector device 112. The detector device 112 comprises at least one optical element 116 configured to separate incident light into a spectrum of constituent wavelength components. The optical element 116 may in particular comprise at least one wavelength-selective element 118. In the exemplary embodiment shown in FIG. 1, the wavelength-selective element 118 may be a linear variable filter 120. However, other options such as a prism, a diffraction grating, an optical filter, in particular a narrow band-pass filter, are also feasible.

[0085] The detector arrangement 112 further comprises a plurality of photosensitive elements 122, each photosensitive element 124 configured to receive at least a portion of one of the constituent wavelength components and to generate a respective detector signal in response to illumination of the respective photosensitive element 124 by at least a portion of each of the constituent wavelength components.

[0086] As seen in FIG. 1, the detector device 112 may comprise a number of photosensitive elements 122 arranged in a linear array 126. The linear array 126 of photosensitive elements 124 may comprise a number of photosensitive elements 124 of 256. Each photosensitive element 124 may be an inorganic photoconductor comprising PbS. However, other configurations or sizes of the linear array and / or other photoconductors are also feasible. Each photosensitive element 124 may be sensitive to electromagnetic radiation in the wavelength range of 1 μm to 3 μm.

[0087] The system 110 further comprises at least one broadband light source 128 and at least one optical interferometer 130 arranged to illuminate the detector arrangement 112 with the broadband light source 128 via the optical interferometer 130. The broadband light source 128 may comprise, by way of example, at least one incandescent lamp 132. However, other broadband light sources 128, such as blackbody radiators, light emitting diodes and / or electric filaments, are also feasible.

[0088] As seen in FIG. 1 , the optical interferometer 130 may be composed of at least one Michelson interferometer 134. However, other optical interferometers, such as a Fabry-Perot interferometer and / or a cube-corner interferometer, are in principle feasible. In this example, the optical interferometer 130 comprises at least one beam splitting device 136 for splitting the incoming light, in particular the incoming light from the broadband light source 128, into at least two illumination paths. The optical interferometer 130 may further comprise at least one scanning mirror 138 in a first illumination path 140 and at least one stationary mirror 142 in a second illumination path 144. As indicated by the arrow 146, the scanning mirror 138 may be movable along the first illumination path 140.

[0089] The system 110 further comprises at least one evaluation unit 148, which is configured to perform a method for calibrating the spectrometer arrangement 114 according to the present invention, e.g. according to any one of the embodiments disclosed above and / or any one of the embodiments disclosed in more detail below. The evaluation unit 148 may be configured to exchange data and / or control commands with other elements of the system 110, in particular the detector arrangement 112, in one direction and / or in two directions, as indicated by arrow 150 in Fig. 1. In particular, the evaluation unit 148 may be configured to receive a plurality of detector signals from the detector arrangement 112.

[0090] In Fig. 2, a flow chart of an exemplary embodiment of a method for calibrating the spectrometer device 114 is shown. The spectrometer device 114 may be embodied as shown in Fig. 1: the spectrometer device 114 comprises at least one detector device 112 with at least one optical element 116 configured to separate incident light into a spectrum of constituent wavelength components. The detector device 112 further comprises a plurality of photosensitive elements 122, each photosensitive element 124 configured to receive at least a portion of one of the constituent wavelength components and to generate a respective detector signal in response to illumination of the respective photosensitive element 124 by at least one portion of each of the constituent wavelength components.

[0091] The method includes, by way of example, the following steps, which may be performed in the given order. However, it should be noted that different orders are also possible. Furthermore, one or more of the method steps may be performed once or repeatedly. Furthermore, two or more of the method steps may be performed simultaneously or overlapping in time. The method may include further method steps not listed.

[0092] This method involves the following steps: a) illuminating the spectrometer arrangement 114, specifically the detector arrangement 112, via at least one optical interferometer 130 using at least one broadband light source 128 (indicated by reference numeral 152); b) determining for the plurality of photosensitive elements 122 (indicated by reference numeral 154), in particular for each of the photosensitive elements 124, a plurality of detector signals in response to illumination via the optical interferometer 130 in step a); and c) determining at least one item of calibration information from the plurality of detector signals (depicted by reference numeral 156). Includes.

[0093] Further, in step a), the transmission frequency of the optical interferometer 130 may be varied over a predetermined spectral range, and in step b), the plurality of detector signals may be determined as a function of the transmission frequency of the optical interferometer 130. In step c), at least one item of calibration information may be determined by comparing the transmission frequency of the optical interferometer 130 with at least one of the pixel locations and identification numbers of the plurality of photosensitive elements 122 that produce intensity peaks of the plurality of detector signals associated with the transmission frequency.

[0094] As outlined above, the optical interferometer 130 may comprise at least one scanning mirror 138 in a first illumination path 140 and at least one stationary mirror 142 in a second illumination path 144. The scanning mirror 138 may be movable along the first illumination path 140. In the method, particularly in step a), the scanning mirror 138 may be moved along the first illumination path 144 and the stationary mirror 142 may remain stationary. The scanning mirror 138 may be moved in steps with a step frequency of 1 kHz or less, particularly with a step frequency of 100 Hz or less, more particularly with a step frequency of 10 Hz or less.

[0095] Further, in step b), the multiple detector signals may be determined for multiple positions of scanning mirror 138 in first illumination path 140. The multiple positions of scanning mirror 138 may be different from one another. Further, as shown in FIG. 2, step c) may specifically include correlating the multiple detector signals with multiple positions of scanning mirror 138 (as indicated by reference numeral 158) prior to processing the multiple detector signals. Thus, in step c), the multiple detector signals correlated to the multiple positions of scanning mirror 138 may be used to determine at least one item of calibration information.

[0096] Further, as shown in Fig. 2, step c) may comprise processing the plurality of detector signals determined in step b), thereby obtaining a plurality of processed detector signals (indicated by reference numeral 160). The determination of the at least one item of calibration information in step c) may comprise determining the at least one item of calibration information from the plurality of processed detector signals. In particular, the processing of the plurality of detector signals may comprise transforming, in particular mathematically transforming, the plurality of detector signals. For example, the plurality of detector signals may be transformed using at least one Fourier transform, in particular at least one discrete Fourier transform.

[0097] The items of calibration information may include at least one of an item of wavelength calibration information and an item of stray light calibration information. The items of wavelength calibration information may include at least one wavelength calibration function. The wavelength calibration function may assign at least one of pixel positions and identification numbers of the light sensitive elements 124 to wavelength positions. For example, the wavelength calibration function may include a polynomial function. However, other wavelength calibration functions are also feasible. The items of stray light calibration information may include at least one signal distribution function, in particular at least one signal distribution matrix. The signal distribution function represents a distribution of responses of the plurality of light sensitive elements 122, in particular the distribution of responses of each light sensitive element 124, to incident light having a particular wavelength. By way of example, the calculation and / or application of the signal distribution matrix is ​​described in further detail in Y. Zong, SW Brown, BC Johnson, KR Lykke and Y. Ohno: "Simple spectral stray light correction method for array spectroradiometers", Applied Optics, Vol. 45, No. 6, 2006.

[0098] Illustrative diagrams of stray light calibration, specifically diagrams corresponding to a number of sub-steps for determining an item of stray light calibration information, are shown in Figures 3A-3D. In Figure 3A, a number of processed detector signals 162 are shown for different transmission frequencies of the optical interferometer 130. Specifically, in the diagram of Figure 3A, the signal intensity 164 of the processed detector signals is shown as a function of pixel position 166 of the number of photosensitive elements 122. Figure 3A shows a number of processed detector signals 162 for several transmission frequencies of the optical interferometer 130, specifically corresponding to a transmission wavelength of 1456 nm (indicated by reference number 168), a transmission wavelength of 1664 nm (indicated by reference number 170), a transmission wavelength of 1840 nm (indicated by reference number 172), a transmission wavelength of 2057 nm (indicated by reference number 174), a transmission wavelength of 2241 nm (indicated by reference number 176), and a transmission wavelength of 2446 nm (indicated by reference number 178).

[0099] The processing of the detector signals may include applying one or more of an offset correction and a digital filter to the detector signals. FIG. 3B shows the processed detector signals 162 after application of an offset correction and a digital filter, such as a Savitzky-Golay filter. Specifically, in the diagram of FIG. 3B, the signal intensities 164 of the processed detector signals are shown as a function of pixel location 166 of the photosensitive elements 122. In FIG. 3B, the signal intensities 164 of the transmission frequencies identified in FIG. 3A are shown. In FIG. 3C, the signal intensities 164 of the transmission frequencies corresponding to transmission wavelengths in the range of 1456 nm to 2446 nm are shown (indicated by reference numeral 180). These signal intensity values ​​may be stored in a so-called signal distribution matrix.

[0100] The signal distribution matrix, particularly the inverse of the signal distribution matrix, may be applied to a measured spectrum determined with a calibrated detector arrangement 112. The effect of applying the signal distribution matrix to a measured spectrum is shown in FIG. 3D. In the diagram of FIG. 3D, the relative intensity of the measured spectrum is shown as a function of pixel position 166. In FIG. 3D, an uncorrected measured spectrum 182 of a PET sample is shown, along with a corresponding corrected measured spectrum 184 obtained by applying an item of stray light calibration information, specifically including the signal distribution matrix, to the uncorrected measured spectrum 182. As can be seen in FIG. 3D, applying the item of stray light calibration information can improve the spectral resolution and reduce the effects of stray light. [Explanation of symbols]

[0101] 110 System 112 Detector Equipment 114 Spectrometer equipment 116 Optical elements 118 Wavelength Selection Element 120 Linear Variable Filter 122 Multiple photosensitive elements 124 Photosensitive element 126 Linear Array 128 Broadband Light Source 130 Optical Interferometer 132 Incandescent lamp 134 Michelson Interferometer 136 Beam splitter 138 Scanning Mirror 140 First lighting path 142 Stationary mirror 144 Second Lighting Path 146 Arrow 148 evaluation units 150 Arrow 152 Illuminating the detector device 154 Determining Multiple Detector Signals 156 Determine at least one item of calibration information 158 Correlating Multiple Detector Signals 160 Processing Multiple Detector Signals 162 Multiple Processed Detector Signals 164 Signal Strength 166 pixel position 168 Transmission wavelength 1456nm 170 Transmission wavelength 1664nm 172 Transmission wavelength 1840nm 174 Transmission wavelength 2057nm 176 Transmission wavelength 2241nm 178 Transmission wavelength 2446nm 180 Transmission wavelength range: 1456nm~2446nm 182 Uncorrected measured spectrum 184 Corrected measured spectrum

Claims

1. A method for calibrating a spectrometer device (114), comprising: the spectrometer arrangement (114) comprises at least one detector arrangement (112), the detector arrangement comprising at least one optical element (116) configured to separate incident light into a spectrum of constituent wavelength components, and further comprising a plurality of photosensitive elements (122), each photosensitive element (124) configured to receive at least a portion of one of the constituent wavelength components and to generate a respective detector signal in response to illumination of the respective photosensitive element (124) by at least one portion of each of the constituent wavelength components; Steps below: a) illuminating said spectrometer device (114) via at least one optical interferometer (130) using at least one broadband light source (128); b) determining, for the plurality of photosensitive elements (122), a plurality of detector signals in response to illumination via the optical interferometer (130) in step a); and c) determining at least one item of calibration information from said plurality of detector signals. Including, the optical interferometer (130) comprises at least one beam splitting device (136) for splitting incident light into at least two illumination paths, the optical interferometer (130) further comprising at least one scanning mirror (138) in a first illumination path (140) and at least one stationary mirror (142) in a second illumination path (144); The scanning mirror (138) is moved along the first illumination path (140), while the stationary mirror (142) remains stationary, and the scanning mirror (138) is moved in steps with a step frequency of 1 kHz or less, the step frequency of the scanning mirror (138) being slower than a maximum readout frequency of the detector arrangement (112). method.

2. The method of claim 1 , wherein the optical interferometer (130) is selected from the group consisting of a Michelson interferometer (134), a Fabry-Perot interferometer, and a cube-corner interferometer.

3. 3. The method of claim 1, further comprising: varying a transmission frequency of the optical interferometer (130) over a predetermined spectral range in step a); and determining the plurality of detector signals in response to the transmission frequency of the optical interferometer (130) in step b).

4. 3. The method of claim 1 or 2, wherein in step c) at least one item of calibration information is determined by comparing the transmission frequency of the optical interferometer (130) with at least one of a pixel position (166) and an identification number of the plurality of photosensitive elements (122) producing intensity peaks of the plurality of detector signals associated with the transmission frequency.

5. 3. The method of claim 1, wherein in step b) the plurality of detector signals are determined for a plurality of positions of the scanning mirror in the first illumination path, the plurality of positions of the scanning mirror being different from one another, and step c) includes correlating the plurality of detector signals with the plurality of positions of the scanning mirror, and in step c) the plurality of detector signals correlated to the plurality of positions of the scanning mirror are used to determine at least one item of the calibration information.

6. 3. The method of claim 1 or 2, wherein step c) comprises processing the plurality of detector signals determined in step b), thereby obtaining a plurality of processed detector signals (162), and wherein determining the at least one item of calibration information in step c) comprises determining the at least one item of calibration information from the plurality of processed detector signals (162), and wherein processing the plurality of detector signals comprises transforming the plurality of detector signals, the plurality of detector signals being transformed using at least one Fourier transform.

7. The method of claim 1 or 2, wherein the items of calibration information include at least one of an item of wavelength calibration information and an item of stray light calibration information.

8. 3. The method of claim 1, wherein the items of wavelength calibration information include at least one wavelength calibration function, the wavelength calibration function assigning at least one of a pixel location (166) and an identification number of the photosensitive element (124) to a wavelength location.

9. 3. The method of claim 1, wherein the items of stray light calibration information include at least one signal distribution function, the signal distribution function representing a distribution of responses of the plurality of photosensitive elements (122) to incident light having a particular wavelength.

10. A system for calibrating a spectrometer device (114), comprising the spectrometer device (114) with at least one detector device (112), the detector arrangement (112) comprises at least one optical element (116) configured to separate incident light into a spectrum of constituent wavelength components, and further comprises a plurality of photosensitive elements (122), each photosensitive element (124) configured to receive at least a portion of one of the constituent wavelength components and to generate a respective detector signal in response to illumination of the respective photosensitive element (124) by at least one portion of each of the constituent wavelength components; the spectrometer further comprising at least one broadband light source (128) and at least one optical interferometer (130), the broadband light source and the optical interferometer being arranged to illuminate the spectrometer arrangement (114) with the broadband light source (128) through the optical interferometer (130); Further comprising at least one evaluation unit (148), said evaluation unit (148) being configured to perform the method according to claim 1 or 2. System (110).

11. The system (110) of claim 10, wherein the broadband light source (128) comprises at least one of an incandescent lamp (132), a black body radiator, an electric filament, and a light emitting diode.

12. 11. The system of claim 10, wherein the optical element comprises at least one wavelength-selective element, the wavelength-selective element being selected from the group consisting of a prism, a diffraction grating, a linear tunable filter, and an optical filter.

13. The system (110) of claim 10, wherein the detector device (112) comprises the plurality of photosensitive elements (122) arranged in a linear array (126), the linear array (126) of photosensitive elements (124) comprising a number of photosensitive elements (124) between 10 and 1000.

14. A computer program comprising instructions that, when executed by the system (110) of claim 10 relating to the system, cause the evaluation unit (148) of the system (110) to perform a method for calibrating a spectrometer device (114) as described in claim 1 relating to the method.

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