SPECTRAL ANALYSIS SYSTEM, MOBILE DEVICE WITH A SPECTRAL ANALYSIS SYSTEM, A METHOD FOR DETERMINING A CORRECTION FUNCTION FOR IMAGE CORRECTION OF A SPECTRUM ACQUIRED BY A SPECTRAL ANALYSIS SYSTEM AND COMPUTER PROGRAM

Abstract

Spectral analysis system for recording a spectrum with optics that form a beam path, wherein the spectral analysis system is designed to apply a correction function, which is in the form of a matrix, to a recorded spectrum by means of matrix multiplication in order to obtain a modified spectrum, where the matrix is ​​an inverse of a matrix that distributes each spectral sample of an actual or undisturbed spectrum with a certain impulse response to the spectrally corresponding sample and the spectrally surrounding samples of a simulated recorded spectrum, and accumulates the contributions thus obtained for all samples of the simulated recorded spectrum. where the impulse response is determined by measuring a spectrum of a reference radiation source.

Description

Technical field

[0001] Exemplary embodiments according to the invention relate to a spectrometer, a mobile device with a spectrometer, a method for determining a correction function for image correction of a spectrum recorded by a spectrometer and a computer program. Background of the invention

[0002] Various methods for improving / increasing the spectral resolution in spectral instruments are known in the prior art.

[0003] The traditional, and therefore widely used, method relies on two main components: meticulous aberration correction during optical design and adjustment procedures, particularly focus setting, after assembly of the entire system. This typically involves degrees of freedom in the form of actuators of various designs. While very common, these two methods have distinct drawbacks. Correcting optical aberrations often results in complex optical surfaces and tight tolerances. The use of mechanical actuators adds considerable mechanical complexity and thus higher costs, and also hinders mass production of spectral instruments, as adjustment procedures are time-consuming. Furthermore, the need for adjustment, due to the space required for the actuators, impedes miniaturization.Strictly speaking, this approach does not aim to improve or increase the spectral resolution of specific device types, but rather to ensure it through design. In any case, the usual method is ineffective for miniaturized systems and high production volumes.

[0004] In contrast, methods are also known that enable an improvement in spectral resolution using signal processing. These methods involve first recording comparison spectra with a high-resolution spectrometer to create a correction function. The method described in EP 0 983 490 B1 serves as an example of such a procedure. However, this approach involves comparing spectra of identical samples recorded with different spectrometers and can lead to comparatively complex data processing.

[0005] Furthermore, methods for reconstructing spectral data in the field of spectral imaging are known. However, these require a targeted, active modification of the irradiance distribution in the beam path during the measurement process. Such methods are known under the term "coded aperture" and are described, for example, in WO 2007 / 047 732 A2. The necessity of active manipulation during the measurement and the required use of matrix image sensors ultimately render this method unsuitable in the context of the present invention.

[0006] In the field of imaging systems, methods are known that improve image quality, particularly image sharpness, using suitable correction algorithms. These methods are often based on knowledge of the point spread function or other characteristics, such as the movement of the objects being imaged (motion blur). Such methods are used in industrial metrology / image processing or field monitoring / photogrammetry. However, the methods used in this context are only very limitedly applicable to spectral instruments, as wavelength calibration issues must be considered, which are irrelevant in the applications mentioned above.Furthermore, in the examples mentioned above, these methods are generally not specifically incorporated into the hardware optimization process, but rather used to address specific problems such as motion blur or depth-of-field issues. The only thematic connection to a spectral apparatus is that such an apparatus also exhibits potentially flawed optical imaging. The algorithms used are typically iterative processes. Here, iterative convergence must be ensured and the generation of image artifacts avoided. This often leads to a less-than-optimal compromise solution.

[0007] In spectroscopy, dispersive spectrometers, spectrographs, monochromators, and polychromators are often used to record the spectrum of electromagnetic radiation, particularly in the ultraviolet (UV), visible (VIS), and infrared (IR) spectral ranges. These instruments employ a diffraction grating or prism to perform spectral splitting. A key performance parameter in such devices is spectral resolution. Since dispersive spectrometers are optical imaging systems, the resolution is determined, among other things, by the efficiency of the optical imaging. The entrance slit of the spectrometer should be imaged as sharply as possible onto an exit slit, or alternatively, a line detector or camera chip. This ensures that optical aberrations, including potential focus errors, are corrected as effectively as possible.

[0008] The demanding imaging requirements of spectral instruments have thus far necessitated a complex approach to the development and manufacturing of such devices. In a sometimes elaborate optical calculation, optical aberrations are corrected or significantly reduced through optimized optical components and their precise arrangement. This often results in tightly toleranced parts and minimal assembly tolerances. Furthermore, adjustment steps for selected system components are integrated into the assembly process to reduce remaining errors through fine-tuning or, for example, to optimize the focus setting.

[0009] This approach is proving problematic for the development and production of spectral instruments in large quantities and / or very small devices in several respects. In large-scale production, any adjustment procedures are no longer feasible due to time and cost constraints. Furthermore, the often tightly toleranced optical components lead to unacceptable costs. This situation currently prevents the mass production of high-performance spectral instruments and thus also the use of such devices in relevant applications, e.g., environmental measurement technology and food safety.

[0010] In view of this, there is a need for a concept that allows a better compromise between increasing the spectral resolution of a spectral apparatus or ensuring the resolution compared to commercial systems, producing a spectral apparatus in large quantities and as a very small system, relaxing tolerances of optical components installed in a spectral apparatus, and reducing costs.

[0011] EP 0 983 490 B1 and DE 10 2010 014 593 A1 describe the recording of reference spectra using reference samples. DE 10 2006 045 033 A1 describes a correction function intended to compensate for optical aberrations, for which, for example, a spatially and wavelength-dependent deconvolution function is determined. To determine the deconvolution function, the change in a monochrome point caused by the imaging device as a whole, i.e., by the recording device and any upstream optics, is recorded. Summary of the invention

[0012] One embodiment relates to a spectral analysis system for recording a spectrum with optics that form a beam path. The optics can be imaging or beam-shaping. The spectral analysis system, also referred to herein as a spectrometer, is designed to apply a correction function to a recorded spectrum in order to obtain a modified spectrum (corrected spectrum). A memory in which the correction function is stored can be located locally within the spectrometer or externally. A processing unit for applying the correction function to the recorded spectrum to obtain the corrected spectrum can also be located locally within the spectrometer or externally. The optics can exhibit imaging defects such as spherical aberrations, astigmatism, coma, defocus, and / or chromatic aberration.Due to optical aberrations, for example, the recorded spectrum deviates from the intended spectrum. Because the spectrometer's processing unit applies a correction function to the recorded spectrum, the influence of these optical aberrations can be reduced. Thus, this spectrometer produces a corrected spectrum with better resolution due to fewer optical aberrations than the spectrometer's original spectrum. The corrected spectrum, for example, exhibits only minor differences from the intended spectrum.

[0013] This embodiment of the spectrometer is based on the understanding that by applying the correction function to the recorded spectrum, optical aberrations of the spectrometer can be compensated for so effectively that it is no longer necessary to correct these aberrations through mechanical adjustment of spectrometer components, such as the optics. For example, the spectral analysis system can process the recorded spectra so that the spectrometer, despite its aberrations, produces a corrected spectrum that differs only slightly from the actual recorded spectrum. Thus, by applying the correction function to the recorded spectrum, it is possible to increase the spectral resolution of the spectrometer. The corrected spectrum of the spectrometer more closely resembles the actual recorded spectrum than the original, recorded spectrum. Furthermore, the spectrometer can, for example,This spectrometer can be produced in large quantities and as a very small system because it eliminates the need to correct optical aberrations through subsequent adjustment or to accept very small optical tolerances. Because the optics, for example, are permitted to have large tolerances, it is easier to manufacture the individual components of the spectrometer and then assemble them, thus enabling mass production. Furthermore, the spectrometer described here allows for its production as a very small system. The smaller a spectrometer is, the smaller the required tolerances for its optics tend to be. Manufacturing small spectrometers, due to the small tolerances required for components such as the optics, is a very complex and costly process. Moreover, for example...It is difficult to incorporate adjustment elements into a small spectrometer to reduce imaging errors after production. The spectrometer described here can be produced without complex and costly manufacturing processes because imaging errors caused by the spectrometer's optical hardware do not need to be compensated for during production, but can be corrected using software, for example. The spectrometer described here may exhibit imaging errors because applying a correction function to the recorded spectrum reduces the influence of these errors and thus increases the spectral resolution of the spectrometer. Therefore, the spectrometer described here can be produced as a small system with minimal effort. Because the spectrometer can be implemented as a small system, it is portable.This eliminates the need to transport samples to the laboratory for spectrometer analysis. Samples can now be analyzed directly on-site using the small, portable spectrometer.

[0014] It can therefore be concluded that the spectrometer can increase the spectral resolution of the spectral apparatus with larger tolerances of the optical components, thus enabling the production of the spectrometer in large quantities and / or as a very small system while reducing costs.

[0015] One embodiment involves a mobile device with an integrated spectrometer. This allows the spectrometer to be used in different locations, rather than being limited to a fixed location such as a laboratory. The use of the spectrometer described herein makes it possible to integrate a spectrometer into a mobile device, as it can be manufactured cost-effectively and in large quantities while maintaining good spectral resolution.

[0016] One embodiment provides a method for determining a correction function for correcting the imaging of a spectrum acquired by a spectrometer. The method comprises acquiring a reference spectrum from a reference radiation source with the spectrometer to obtain a reference spectrum, wherein the spectrum of the reference radiation source has a spectral bandwidth smaller than the spectral resolution of the spectrometer, and creating a correction function from the acquired reference spectrum such that, when the correction function is applied to spectra acquired by the spectrometer, corrected spectra are obtained that are less affected by imaging errors in the spectrometer's optics. For example, the method can be used to create a correction function with which spectrometers can correct specific imaging errors, e.g.,The optical limitations of the spectrometer can be at least partially compensated for. Thus, the method optimizes, for example, the spectral resolution of the spectrometer.

[0017] One embodiment relates to a computer program with program code for carrying out a procedure when the program runs on a computer. Character description

[0018] Exemplary embodiments according to the present invention are explained in more detail below with reference to the accompanying figures. These show: Fig. 1 a schematic representation of a spectrometer according to an embodiment of the present invention; Fig. 2 a schematic representation of a spectrometer with a sensor element according to an embodiment of the present invention; Fig. 3 a schematic representation of a spectrometer with a detector element according to an embodiment of the present invention; Fig. 4a a schematic representation of a mobile device with a spectrometer according to an embodiment of the present invention; Fig. 4b a schematic representation of a mobile device with a spectrometer and a processing unit integrated in the mobile device according to an embodiment of the present invention; Fig. 5 a schematic representation of a close-up of the exit aperture of a spectrometer according to an embodiment of the present invention; Fig. 6 a schematic representation of a magnified section of the spectrometer's exit aperture when defocus is present as an imaging error; Fig. 7 a diagram of a very narrowband spectrum of a reference source for determining a correction function for the spectrometer according to an embodiment of the present invention; Fig. 8 a diagram of a recorded reference spectrum with a spectrometer with correct focus position according to an embodiment of the present invention; Fig. 9 a diagram of a reference spectrum of a spectrometer with defocus according to an embodiment of the present invention; Fig. 10 a diagram of a spectrum recorded by a spectrometer according to an embodiment of the present invention; Fig. 11 a schematic representation of a corrected spectrum of a spectrometer according to an embodiment of the present invention; Fig. 12 a block diagram of a method for determining a correction function for imaging a spectrum recorded by a spectrometer according to an embodiment of the present invention; and Fig. 13 a block diagram of a method for determining and applying a correction function of a spectrometer according to an embodiment of the present invention. Detailed description of the embodiments according to the figures

[0019] Before exemplary embodiments of the present invention are explained in detail below with reference to the drawings, it should be noted that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0020] Fig. Figure 1 shows a schematic representation of a spectral analysis system 100 according to an embodiment of the present invention for recording a spectrum 110 with an imaging optic 120. The spectral analysis system, hereinafter referred to as the spectrometer 100, comprises, for example, a memory 130 in which a correction function is stored. Furthermore, the spectrometer 100 comprises, for example, a processing unit 140 for applying the correction function to a recorded spectrum 112 in order to obtain a corrected spectrum 114.

[0021] In Fig. Although the spectrum 110 to be recorded is shown in a diagram (intensity versus wavelength), it is not necessary to know the diagram containing the spectrum to be recorded. For example, a light source with an unknown spectrum to be recorded could be located at this point, or it could be radiation reflected or transmitted by a sample. The radiation of the spectrum 110 to be recorded enters the spectrometer 100, where it is directed and focused by the imaging optics 120 and spectrally dispersed by a spectral dispersing element of the spectrometer 100. The resulting spectrum 112 obtained by the spectrometer 100 differs from the spectrum 110 to be recorded in that it is altered (impaired) by imaging errors of the imaging optics 120 of the spectrometer 100, for example.The greater the imaging errors of the imaging optics 120 of the spectrometer 100, the greater, for example, the deviation of the recorded spectrum 112 from the target spectrum 110. To increase the resolving power (the spectral resolving power) of the spectrometer 100, the recorded spectrum 112 is forwarded to the processing unit 140. The processing unit 140 retrieves the correction function from the memory 130 and applies it to the recorded spectrum 112 to obtain the corrected spectrum 114.

[0022] The correction function thus enables a spectrometer configuration that allows the spectral resolution of a spectrometer (Spectrometer 100) with imaging errors (including defocus) to be increased computationally, i.e., without interfering with the system's opto-mechanical hardware. This opens up the possibility, when building spectrometers, especially in very large quantities and with very small systems, of completely eliminating the usual adjustment process and / or no longer correcting certain imaging errors, thereby relaxing tolerances and significantly reducing costs. Imaging errors are deliberately accepted, the impact of which on the resolution is corrected retrospectively in the signal (spectrum).

[0023] In one embodiment, the correction function is in the form of a matrix which, when applied to the recorded spectrum 112, yields the corrected spectrum 114. The corrected spectrum 114 is obtained by multiplying the recorded spectrum 112 by a matrix. The matrix can, for example, be...by inverting a matrix that distributes each spectral sample of an actual or undisturbed spectrum with a certain impulse response to the spectrally corresponding sample and the spectrally surrounding samples of a simulated recorded spectrum, and accumulates the contributions thus obtained for all samples of the simulated recorded spectrum, i.e., by inverting a matrix that essentially simulates the deviation of the recorded spectrum from an undisturbed spectrum caused by imaging errors, whereby the impulse response can be determined by measuring a recorded spectrum 112 of a reference radiation source, as will be described below. The reference radiation source can be, for example,A laser, an LED, a narrowband thermal radiation source, or a combination of light source and monochromator, produces a spectrum to be recorded that has a bandwidth smaller than the spectral resolution of the spectrometer. The invertibility of the matrix offers an advantage. Determining the correction matrix by inverting a matrix constructed from one or more measured impulse responses is possible because this impulse response matrix—that is, the synthetic imaging matrix composed of the individual spectral impulse responses—is, in principle, regular and therefore invertible. This allows the use of non-iterative correction methods with significant advantages in terms of time and accuracy. Furthermore, algorithm-related artifacts are either absent or minimal. In any case, precise knowledge of the entire spectrum of the reference radiation source is not required; only, for example, the position of the maximum spectral line is necessary.In particular, the shape of individual spectral lines or narrow bands is then no longer significant, since the spectral width is, by definition, considerably smaller than the resolution of the spectrometer. Any resulting inaccuracy in the wavelength position of the corresponding line is therefore negligible. Because the correction function is in the form of a matrix, the processing unit 140 can apply the correction function to the recorded spectrum 112 in an energy-efficient manner to obtain the corrected spectrum 114, since the application of the correction function in this case consists only of matrix multiplication of a vector, consisting of the samples of the recorded spectrum, by the correction matrix. Typical sizes for such matrices are, for example, approximately 256x256 or 512x512, 1024x1024, or even larger, depending on the spectral range and the required spectral resolution.The correction matrix can therefore be mxn in size, where n,m > 128, where, for example, n corresponds to the number of spectral samples of the recorded spectrum, i.e., the number of spectral values ​​of the spectrometer.

[0024] In one embodiment, the spectral analysis system 100 is configured to perform an integral transformation or matrix manipulation when a correction function is applied. In the spectrometer 100 made of Fig. For example, processing unit 140 is configured to perform matrix multiplication or, more generally, matrix manipulation when applying the correction function. However, the application of the correction function can also consist of a numerical convolution or inverse numerical convolution if the correction function is known, for instance, as a functional relationship. In general, the application of the correction function can consist of an integral transformation. The integral transformation can thus involve a convolution or an FFT (Fast Fourier Transform), and / or the matrix manipulation can involve matrix multiplication. Because no prior knowledge of the recorded spectrum is required for correction when using the spectrometer, the effort associated with spectrum improvement is minimal.It is made possible to apply the correction function to the recorded spectrum 112 in a performance- and time-efficient manner in order to obtain the corrected spectrum 114.

[0025] Fig. Figure 2 shows a schematic representation of a spectrometer 100 for recording a spectrum 110 with an optical system 122 according to an embodiment of the present invention. The optical system 122 with the imaging optics 120 is designed to spectrally split the electromagnetic radiation (of the spectrum 110 to be recorded). The optical system 122 is, for example, a monochromator, a polychromator, or a device designed to perform hyperspectral imaging. Thus, the optical system 122 enables the spectrometer 100 to spectrally split the electromagnetic radiation of the spectrum 110 to be recorded and thereby analyze the spectral composition of the spectrum 110.

[0026] In one embodiment, the optical system 122 has no adjustment elements and / or no mechanical actuators to correct imaging errors after the spectrometer 100 has been manufactured. It is also possible that an inlet aperture, an outlet aperture, and components of the optical system 122 are fixed relative to each other and without adjustment. In this case, for example, the electromagnetic radiation of the spectrum 110 to be recorded enters the optical system 122 of the spectrometer 100 through the inlet aperture, is spectrally split within the optical system 122, and then exits the spectrally splitted optical system 122 through the outlet aperture. The components of the optical system 122 are positioned relative to each other, for example, such that the electromagnetic radiation is spectrally split, and only radiation with a specific, adjustable spectral bandwidth exits through the outlet aperture.The radiation exiting the optical system 122 is, for example, received by a detector element 150 of the spectrometer 100. Because the optical system 122 has no adjustment elements and / or mechanical actuators—meaning, for example, that the entrance aperture, the imaging optics, the exit aperture, and components of the optical system are fixed and aligned relative to one another—the spectrometer 100 can be mass-produced. This is because, once all elements of the optical system 122 of the spectrometer 100 have been arranged, no further adjustments are necessary. The spectrometer 100 can therefore be mass-produced, as the complex adjustment procedures that would otherwise be required for each individual spectrometer 100 after production are no longer necessary.Since adjustment elements and mechanical actuators for correcting imaging errors would take up considerable space in the spectrometer 100, the spectrometer 100 described herein can be implemented as a small system without these adjustment elements and mechanical actuators. The inlet and outlet openings can be round, oval, rectangular, crescent-shaped, arcuate, square cushion-shaped, square barrel-shaped, or other shapes.

[0027] The spectrometer 100 comprises, for example, at least one detector element 150 designed to detect the electromagnetic radiation split by the optical system 122. The recorded spectrum 112 is generated from the data acquired by the at least one detector element 150. The recorded spectrum 112 is forwarded to a processing unit 140. The processing unit 140 retrieves a correction function from a memory 130 and applies this function to the recorded spectrum 112 to obtain a corrected spectrum 114. For example, it is not necessary for the memory 130 to be located within the spectrometer 100, nor for the latter to contain the former. The memory can also be implemented, for example, as a cloud or in an external device to which the unit 140 has access, or from which the unit 140 receives the correction function. The processing unit 140 can be connected to the memory 130, for example.The connection can be wired or wireless, such as via Wi-Fi, Bluetooth, ZigBee, etc. Additionally or alternatively, the processing unit can be located externally, meaning the actual application is performed by sending the captured spectrum to the processing unit to execute the application locally.

[0028] In one embodiment, the correction function stored in memory 130 is generated by a method as described below. For this purpose, the spectrum 110 to be recorded has at least one spectral peak, i.e., a spectral line or a spectral band, with a bandwidth smaller than the spectral resolution of the spectrometer 100. In other words, the spectrometer 100 records the spectrum from a reference radiation source with a spectral peak that, for example, has a bandwidth smaller than the spectral resolution of the spectrometer 100. The spectrum of the reference radiation source does not need to be known precisely. For example, only the spectral position of the spectral maximum is known. The recorded spectrum then represents, as it were, the impulse response of the spectrometer at the spectral maximum (or spectral line) of the reference source. The procedure can be adapted as needed.The process is repeated for further spectral positions of the reference source spectrum maximum. The recorded spectrum 112 is forwarded to the processing unit 140. In the processing unit 140, the recorded spectrum 112 is used, for example, to create a matrix that distributes each spectral sample of an actual or undisturbed spectrum with a certain impulse response to the spectrally corresponding sample and the spectrally surrounding samples of a simulated recorded spectrum, and accumulates the contributions thus obtained for all samples of the simulated recorded spectrum. This matrix then essentially simulates the deviation of the recorded spectrum from an undisturbed spectrum caused by imaging errors. Its columns would correspond to impulse responses for the different sampling positions and would be derived from the one or more recorded spectra, for example, by interpolation.The processing unit 140 then determines, for example, the correction function for image correction of a spectrum 112 recorded by the spectrometer 100. The correction function can be determined, for example, by the processing unit 140 by inverting the aforementioned matrix. This inverted matrix can then be stored in the memory 130 as a correction function. Thus, it is possible for the spectrometer 100 to determine a correction function independently. This corrects or qualitatively improves the recorded spectra 112 of the spectrometer 100 into a corrected spectrum 114, since the correction function in the memory 130 at least partially reverses the individual imaging errors of the imaging optics 120 of the spectrometer 100. Thus, for example, each spectrometer 100 has an individual correction function.This measure increases the spectral resolution of the spectrometer 100 and makes it possible to individually compensate for imaging errors of the spectrometer 100, thereby allowing tolerances of the optical components (the imaging optics 120) to be relaxed.

[0029] In one embodiment, the spectrometer 100 comprises a sensor element 160 designed to detect an environmental condition. Alternatively, the spectrometer could also learn the environmental condition via external sensors and use it as described below. The spectrometer 100 is configured to determine the correction function of the spectral analysis system 100 depending on an environmental condition, e.g., to look up a different function depending on the existing condition, or to apply it depending on the condition, e.g., via environmental condition-specific correction manipulations or functions. The sensor element 160 can detect, for example, temperature, humidity, atmospheric pressure, and / or combinations of these environmental conditions. By having the spectrometer 100, for example,The sensor element 160 enables the processing unit 140 of the spectrometer 100 to read an environment-condition-dependent correction function from the memory 130 and apply it to the recorded spectrum 112 to obtain a corrected spectrum 114. Thus, the spectrometer 100 described herein is designed to increase its spectral resolution by correcting environment-condition-dependent imaging errors. The environment-condition-dependent correction function can be determined by performing the aforementioned derivation of the correction function for different environmental conditions to obtain a set of correction functions, or by generating a correction function that is parameterizable with respect to the environmental conditions. For this purpose, the environmental conditions are recorded during each measurement of the reference source spectrum.

[0030] In one embodiment, the spectrometer 100 is designed to determine a correction function for image correction of a spectrum recorded by a spectrometer (spectrum to be recorded 110) depending on ambient conditions. For this purpose, a reference spectrum is provided as the spectrum to be recorded 110, which has a spectral peak with a bandwidth smaller than the spectral resolution of the spectrometer 100. The spectrum to be recorded 110 is spectrally split in the optical system 122 and recorded by the detector element 150. This results in the recorded spectrum 112, which is then forwarded to the processing unit 140. Simultaneously, for example, the sensor element 160 records the ambient conditions present during the measurement and transmits them to the memory 130.The processing unit 140 converts the recorded spectrum 112 into a correction function and sends it to the memory 130, where the correction function determined by the spectrometer 100 is stored together with the corresponding environmental conditions. The correction function was determined by the spectrometer 100 such that, by applying the correction function, e.g., by the processing unit 140 of the spectrometer 100, to recorded spectra 112 taken by the spectrometer 100, corrected spectra 114 are obtained that are less affected by imaging errors of an imaging optic 120 of the spectrometer 100. Thus, for example, several correction functions can be stored in the memory 130 for different environmental conditions.

[0031] The above embodiments enable the production of spectrometers with an improved ratio between manufacturing effort and accuracy. EP 0 983 490 B1 describes an improvement in the spectral resolution of a spectrometer using signal processing. Reference spectra are acquired with a high-resolution spectrometer to create a correction function. However, this approach involves comparing spectra of identical samples acquired with different spectrometers and can lead to comparatively complex data processing. The resolution improvement described there is based on a comparison with a known spectrum of the same sample. In contrast, the spectrometer described here is based on the acquisition of spectrometer properties, independent of known reference spectra.This leads to significantly more universal applicability, since the spectrum of the samples to be measured is precisely unknown in the field. In other words, the spectrometer 100 described herein does not require a reference spectrum. Instead, the imaging errors are determined once with sufficient accuracy, and at least one correction function is derived from this. The correction function can reduce the influence of the imaging errors on the recorded spectrum for different spectral ranges. Because a reference radiation source with a bandwidth smaller than the spectral resolution of the spectrometer is used to determine the correction function, the correction function is, for example, a type of spectral point image function (not a reference spectrum as in the prior art).This represents a significant simplification compared to the state of the art and thus enables the economical production and operation of large quantities of spectral instruments.

[0032] It should be noted that here, a spectrometer 100 is understood to be a device that can consist of several modules with different functions. An optical module (optical system 122), for example, essentially represents the optical beam path for decomposing the electromagnetic radiation to be measured (spectrum to be recorded 110) into its spectral components. The module can include an optical component for decomposing electromagnetic radiation in the form of a diffraction grating or prism. The grating can be planar, concave, or convex. Furthermore, the grating itself can be aberration-corrected (adjusted shape and position of the individual grating lines). In the case of a prism, it can also have different shapes, e.g., planar surfaces (standard triangular shape) or non-planar surfaces (e.g., Féry prism). These can be, for example, monochromators, polychromators, or imaging polychromators.The electromagnetic radiation to be analyzed can be in the UV, VIS, or IR spectral range. Possible spectral ranges are, for example, VIS: 400 nm - 1100 nm, NIR: 800 nm - 1600 nm, NIR: 1000 nm - 1900 nm, NIR: 1150 nm - 2300 nm, NIR: 1250 nm - 2500 nm, IR: 3000 nm - 6000 nm, or ranges where the lower limit is greater than or equal to 50% of the specified limit and the upper limit is less than or equal to 200% of the specified limit. Another component includes, for example, the detector (at least one detector element 150), with corresponding control electronics for detecting the radiation and converting it into a measurement signal (recorded spectrum 112). These can be detectors with only one element or with multiple elements (line or matrix sensors). In addition to the detector assembly, there is, for example, electronics that contain a data storage device (memory 130) and possibly other components.It enables signal preprocessing and is designed for communication with other devices, e.g., a PC.

[0033] The exemplary embodiments are based on a holistic view of the system. This includes not only the "hardware," essentially the beam path with its optical components (optical system 122 with the imaging optics 120) and the detector with its associated electronics, but also, for example, signal processing and data preparation (a "holistic" system approach). This makes it possible to generate an optimized overall system while taking into account the specific advantages of the individual subsystems. Crucially, in such an approach, not every subsystem needs to be optimized in every aspect; rather, the system design focuses on optimizing the interaction of the different components. This results not only in technical but also, in most cases, in economic advantages compared to the prior art.

[0034] The construction of spectrometers requires not only good aberration correction (costly) for good spectral resolution, but almost always also adjustment of the beam path (focus adjustment). This effort, especially the adjustment, currently prevents the mass production of spectrometers at acceptable costs. In the Spectrometer 100, the adjustment process is completely eliminated in favor of modified data processing. Within certain limits, this also applies to the correction of the system; certain imaging errors, such as defocus, spherical aberration, astigmatism, coma, field curvature, and / or chromatic aberration, no longer need to be fully corrected because the resulting loss of resolution can also be compensated for by suitable data processing. For the [unclear - possibly "in the context of the Spectrometer 100"], the [unclear - possibly "in the context of the Spectrometer 100"] Fig. The spectrometers shown, for example, can be used to correct the significantly increasing errors of spherical aberration, astigmatism, and coma by relaxing tolerances and using a simpler optical surface shape for the large concave mirror, which can be a spherical mirror, as described above. The same applies to defocus. This results in a significant cost advantage due to less expensive optical components and less stringent tolerances for components and the overall system.

[0035] Fig. Figure 3 shows a schematic representation of a scanning spectrometer 100 according to an embodiment of the present invention. Electromagnetic radiation 8 enters the optical system 122 through an entrance aperture 1 (entrance slit) and strikes a mirror 5 (imaging optics), which collimates the radiation and directs it onto a rotatable diffraction grating 3. A portion of the radiation 9 diffracted by the grating 3 strikes the mirror 5 again and is focused by it onto the exit aperture 2 (exit slit). Behind the exit aperture 2 is a detector element 6 for detecting the radiation and subsequently converting it into an electrical signal. Furthermore, the spectrometer 100 contains an electronic data storage device 7 in which device-specific data correlated with the imaging errors are stored. The storage device 7 is electronically connected to the detector 6 and the peripherals via data lines 10. The storage device 7 can, for example,the same function as the 130 in memory. Fig. 1 and Fig. 2 exhibit and the detector element 6 can, for example, have the same functionalities as at least one detector element 150 made of Fig. 2. The data acquired by the detector element 6 regarding the spectral properties of the electromagnetic radiation 8 is stored, for example, as a spectral intensity distribution in the form of a matrix in the memory 7. The processing unit 140 retrieves, for example, the acquired spectrum from the memory 7, e.g., in the form of the matrix, and the device-specific data correlated with the imaging errors, in order to convert the acquired spectrum into a corrected spectrum. For the conversion, the processing unit 140 applies a correction function, which is available in the form of the device-specific data correlated with the imaging errors, to the acquired spectrum. The spectrum is acquired by a rotation 4 of the grating 3 in the spectrometer 100 and the time-sequential acquisition of the signal at the detector 6. The subsequent further processing of the data can be carried out in another part of the electronics, such as...in processing facility 140.

[0036] Fig. Figure 4a shows a schematic representation of a mobile device 200 in which the spectrometer 100 described herein is integrated, according to an embodiment of the present invention. The mobile device 200 is designed to receive electromagnetic radiation 210 and transmit it to the spectrometer 100. The spectrometer 100 has, for example, the same functionalities as the spectrometer 100 of Fig. 1, Fig. 2 and Fig. 3. The spectrometer 100 generates a corrected spectrum 114, which is sent, for example, in the form of a diagram to a display 220 of the mobile device 200 and is displayed on the display 220 for the user.

[0037] In one embodiment, the mobile device 200 with the spectrometer 100 does not have a display 220. In this case, the mobile device 200 can be connected, for example, wirelessly or via a cable to an external device, such as a computer and / or a screen, in order to display and / or further process the corrected spectrum on the external device.

[0038] The electronics of the mobile device 200 for the spectrometer 100, for example, perform tasks such as storing the correction function, calculating the application of the correction function to the recorded spectrum, and / or measuring environmental conditions. Particularly for mobile devices (mobile device 200) such as smartphones, tablet computers, PDAs (Personal Digital Assistants), notebooks, and / or GPS devices, enormous quantities of spectrometers are required. In such devices, some of the existing electronic infrastructure can then be used for the operation of the spectrometer.

[0039] For example, as schematically shown in Fig. Figure 4b shows that part of the electronics of the mobile device 200 forms the processing unit 140 of the spectrometer 100, according to an embodiment of the present invention. The mobile device 200 consists of Fig. 4b can, for example, have the same functionalities as the mobile device 200. Fig. 4a. Electromagnetic radiation 210 is emitted, for example, by the mobile device 200 in Fig. 4b is recorded and transmitted to the spectrometer 100. The spectrometer 100 spectrally splits the electromagnetic radiation 210 and records a spectrum, which it then transmits to the processing unit 140. The processing unit 140 retrieves a correction function either from the spectrometer 100's internal memory, from the mobile device 200's internal memory, or from a cloud or other external device to which the mobile device 200 is wirelessly connected. The processing unit 140 applies the correction function thus obtained to the spectrum recorded by the spectrometer 100, thereby generating a corrected spectrum 114, which is displayed, for example, on the display 220 of the mobile device 200.

[0040] Fig. Figure 5 shows a schematic representation of an outlet opening 2 (e.g., a close-up of the outlet opening 2 of the spectrometer 100, shown in Fig. 3) with a beam 9 of diffracted radiation passing through the slit (exit aperture 2), according to an embodiment of the present invention. In this example, the focus position of the spectrometer to which the exit aperture 2 belongs is correctly adjusted. The focus is located at the slit position, thereby achieving the nominal resolution of the spectrometer by means of adjustment. A second beam 19, belonging to radiation of a different wavelength, is completely blocked at the slit 2, so that selectively only light of a specific wavelength can pass through the exit aperture 2.

[0041] In the prior art, the components of the spectrometer's optical system had to be painstakingly adjusted to ensure that the focus was at the slit position, as in Fig. Figure 5 shows the situation. With the spectrometer described herein, this adjustment is no longer necessary, for example. The spectrometer's processing unit 140 applies a correction function to the recorded spectrum in order to reduce imaging errors such as an incorrect focus position and to produce a corrected spectrum that shows hardly any deviations from a recorded spectrum with correct focus, as for example in Fig. 5 shown, has.

[0042] Fig. 6 also shows how Fig. 5 an exit opening 2 with a beam 9 of diffracted radiation according to an embodiment of the present invention. In contrast to Fig. Figure 5 illustrates a defocus as an example of an imaging error. The radiation 9 is focused in front of the slit (exit aperture 2). As a result, not all of the radiation can pass through the slit. Furthermore, radiation from the beam 19 of a different wavelength can also partially pass through the slit, leading to a reduced spectral resolution.

[0043] The spectrometer described herein can exhibit an imaging error, as in Fig. Figure 6 illustrates this and, for example, the processing unit can at least partially compensate for the imaging error by applying a correction function to the recorded spectrum in order to provide a corrected spectrum. Thus, with the spectrometer described herein, it is no longer necessary to reduce imaging errors of the spectrometer after its manufacture by adjusting components of the spectrometer's optical system. This allows the spectrometer described herein to be manufactured more simply and cost-effectively.

[0044] Fig. Figure 7 shows a very narrowband spectrum of a reference source, which can be used, for example, as an input signal into the spectrometer 100 in Fig. 1, Fig. 2, Fig. 3, Fig. 4a and / or Fig. 4b can be used to determine a correction function according to an embodiment of the present invention. The spectral bandwidth of the peak of the spectrum considered here can, for example, be significantly smaller than the spectral resolution of spectrometer 100. In other words, the spectral peak bandwidth is preferably negligible compared to the nominal resolution (without significant imaging errors) of the spectrometer. The diagram in Fig. Figure 7 shows the intensity as a function of wavelength. Considering that in practice the spectral sampling values ​​of the spectrometer are often spectrally much denser than the spectrometer's nominal resolution, i.e., oversampling is achieved, it may be sufficient if the full width at half maximum (FWHM) of the reference spectrum, which should be smaller than the spectrometer's nominal resolution, is, for example, less than twice the spectral sampling distance of the spectrometer. As mentioned, multiple measurements can be performed with reference source spectra of different maximum wavelengths λ0. Furthermore, a reference spectrum with multiple peaks or multiple spectral lines within the spectral range of the recorded spectrometer spectrum can be used.

[0045] Fig. Figure 8 shows, for example, a diagram of a spectrum produced by the spectrometer 100 in Fig. 1, Fig. 2, Fig. 3, Fig. 4a and / or Fig. 4b with correct focus position, as e.g. in Fig. 5 shown, to the input signal, as in Fig. 7 e.g. shown, according to an embodiment of the invention. The one in Fig. The spectrum shown in Figure 8 is recorded at the system's nominal resolution. The diagram shows the intensity as a function of wavelength.

[0046] Fig. Figure 9 shows in a diagram the input signal of the Fig. 7. corresponding spectrum, which the spectrometer with defocus, as e.g. shown in Fig. 6, according to an embodiment of the invention, would thus have a reduced spectral resolution of the system. Since the input signal (see Fig. 7) however, if it has a negligible spectral bandwidth, the signal thus recorded (spectrum in the diagram of Fig. 9) For example, information about imaging errors, specifically defocus. The resulting spectral function can be used as the basis for the correction function for any recorded spectra. The diagram shows the intensity as a function of wavelength.

[0047] Fig. Figure 10 shows a diagram illustrating an example of a measurement using the spectrometer (as in Fig. 1, Fig. 2, Fig. 3, Fig. 4a and / or Fig. 4b) A recorded spectrum according to an embodiment of the present invention is shown, wherein optical aberrations are present in the system (e.g., the optical system). The aberrations lead to a loss of resolution and detail in the spectrum. The diagram shows the intensity as a function of wavelength.

[0048] Fig. Figure 11 shows a diagram illustrating how a corrected spectrum, e.g. of the recorded spectrum from Fig. 10, which may appear after application of the correction function, according to an embodiment of the present invention. The diagram shows the intensity as a function of the wavelength.

[0049] The difference between Fig. 10 to Fig. Reference 11 shows that the spectrometer described herein can improve the spectral resolution of a spectrometer affected by imaging errors without costly modifications to the opto-mechanical hardware of the spectrometer.

[0050] Fig. Figure 12 shows a block diagram for an embodiment of a method according to an embodiment of the present invention. The method is designed to determine a correction function for imaging a spectrum recorded by a spectrometer. To determine the correction function, a narrowband radiation source is first provided to the spectrometer 310. The narrowband radiation source represents a reference radiation source. The reference radiation source for recording the reference spectrum 320 comprises a laser, a narrowband LED, a narrowband thermal radiation source, or a line source. In a further step of the method, the spectrometer records a reference spectrum from the reference radiation source 320 to obtain a recorded reference spectrum.A peak in the spectrum of the reference radiation source has a bandwidth smaller than the spectral resolution of the spectrometer. A further step of the procedure involves creating a correction function from the recorded reference spectrum. When this correction function is applied to spectra recorded by the spectrometer, corrected spectra are obtained that are minimally affected by imaging errors in the spectrometer's optical system. The procedure then involves storing the correction function in a memory. This memory can be located, for example, within the spectrometer itself, or implemented as cloud storage or in an external device. If the memory is implemented as cloud storage or in an external device, the spectrometer is connected to the memory, for example, wirelessly or via a cable.

[0051] The procedure for determining the correction function can be performed, for example, only once, preferably during the commissioning of the spectrometer. The determination of the correction function can be carried out using an input signal whose spectral bandwidth is negligible or at least very small compared to the required instrument resolution. For example, unlike other methods in the prior art, it is not necessary to know the exact shape of this optical input signal (reference radiation source). This correction function can then be used in subsequent measurements, for example, in the form of a convolution or inverse convolution (other, more complex approaches are also conceivable), to correct spectra. From the perspective of optical imaging in the spectrometer, the correction function is, for example, a type of spectral point image function (not a reference spectrum as in the prior art). However, it can vary across the spectral range.Therefore, in some cases, depending on the design of the spectrometer, it may be necessary to determine the correction function at several points in the spectral range.

[0052] In one embodiment, the recording 320 can be carried out one or more times with one or more reference spectra, wherein the one or more reference spectra can have several peaks whose spectral width is each smaller than the spectral resolution of the spectral analysis system, and which have a different spectral position to each other in order to obtain a plurality of recorded impulse response spectra, wherein the creation of a correction function is carried out on the basis of the plurality of impulse response spectra.

[0053] In one embodiment, the acquisition 320 is repeated for several reference spectra 350, each exhibiting a peak with a spectral width smaller than the spectral resolution of the spectrometer and having different spectral positions, such as their respective maximums, in order to obtain a plurality of recorded reference spectra or a plurality of recordings of impulse responses, namely impulse responses at different spectral positions of the spectrometer spectrum. The acquisition of several reference spectra is repeated, for example, x times, where x ≥ 2. Thus, for example, at x = 7, seven narrowband radiation sources can be provided to the spectrometer 310, wherein a first narrowband radiation source is, for example,One narrowband radiation source has a wavelength of 400 nm, a second narrowband radiation source a wavelength of 450 nm, a third narrowband radiation source a wavelength of 500 nm, a fourth narrowband radiation source a wavelength of 550 nm, a fifth narrowband radiation source a wavelength of 600 nm, a sixth narrowband radiation source a wavelength of 650 nm, and a seventh narrowband radiation source a wavelength of 700 nm. Thus, the reference radiation sources have different spectral positions of their maximums. For each of these reference radiation sources, a reference spectrum is recorded, for example. 320 The creation of a correction function is carried out using the majority of reference spectra. The spectral position of the narrowband reference radiation sources, or rather...The peak of the reference spectrum can be selected arbitrarily depending on the spectrometer's application. For example, wavelengths within the visible spectrum suitable for human vision can be chosen, but wavelengths outside this range, such as X-rays, ultraviolet radiation, infrared radiation, terahertz radiation, microwaves, etc., can also be selected. By repeatedly recording the reference spectrum for multiple reference spectra, the correction function, which is generated based on the majority of recorded reference spectra, can minimize spectrometer aberrations depending on the spectral position of the radiation within a recorded spectrum. Thus, the correction function addresses individual spectrometer aberrations depending on the spectral position of the radiation. For example, the aberration defocus may be greater at one wavelength than at another. The correction function includes, for example,These differences are due to the spectrometer's imaging errors, meaning that when the correction function is applied to a recorded spectrometer spectrum, a corrected spectrum is produced that minimizes the influence of imaging errors on the recorded spectrum. Thus, an improved corrected spectrometer spectrum is achieved. However, it should be noted that it is possible that the multiple peaks, which in the preceding example were each individually distributed across recorded reference spectra and used for a respective impulse response measurement, could also be partially or even entirely part of a single reference spectrum.In other words, multiple peaks of a reference spectrum, contained within the spectral range of the spectrometer and each exhibiting a narrower spectral width than the spectrometer's resolving power, could be used to generate individual impulse response measurements. These measurements could then be combined with one or more impulse response measurements from other measured reference spectra to construct the aforementioned inverting matrix. Such a multi-peak, multi-band reference spectrum can be generated, for example, using calibration lamps such as argon and krypton lamps.

[0054] In one embodiment, different environmental conditions are provided 360. The reference spectrum is recorded, for example, under different environmental conditions 320 in order to create a correction function for each environmental condition 330. For example, the environmental conditions can be changed by altering the temperature, humidity, pressure, or other properties of the atmosphere inside the spectrometer. Providing different environmental conditions can be achieved, for example, by performing the reference spectrum measurement in a climate chamber, such as by means of one or more elements within it that define the temperature and / or humidity and / or pressure of the environment in which the spectrometer performs the reference spectrum measurement.Creating a correction function for each environmental condition—that is, having different correction functions for different environmental conditions—makes it possible to minimize spectrometer imaging errors in a corrected spectrum, depending on the varying environmental conditions. For example, elevated temperatures within the spectrometer can cause the imaging optics to expand, resulting in larger imaging errors than at lower temperatures. While the spectrometer is recording a spectrum, environmental conditions can be measured via a sensor element. This allows the spectrometer's processing unit to apply a correction function appropriate to the environmental conditions to the recorded spectrum, thus obtaining a corrected spectrum.Thus, by determining a correction function for each environmental condition, the further influence of imaging errors of the spectrometer on the recorded spectrum is minimized, thereby improving the corrected spectrum and thus improving the resolving power of the spectrometer.

[0055] In one embodiment, the correction function is stored in a memory of the spectrometer together with information about the associated environmental conditions 342, from which the spectral analysis system obtains knowledge of the correction function. For this purpose, the correction function stored in the memory 340 is linked with the environmental conditions stored in the memory 344. The spectrometer's memory does not necessarily have to be located in the spectrometer itself, but can also be implemented in the form of a cloud or in an external device. Each spectrometer, for example, has its own individual memory in which the associated correction functions are stored, which means that differently manufactured spectrometers can exhibit different imaging errors that can be individually minimized by different correction functions in a corrected spectrum.Thus, correction functions linked to the specific environmental conditions are stored in a memory specifically for the spectrometer, minimizing the influence of environmental conditions during measurements. By storing the information (e.g., the environmental conditions) and at least one correction function in the spectrometer's memory, the spectrometer's processing unit can quickly access the appropriate correction function for the measurement.

[0056] In one embodiment, the correction function is parameterized. For example, environmental conditions can be provided as parameters, allowing multiple different correction functions to be created from a single correction function, depending on the parameters. This makes it possible to use less memory in the spectrometer and to generate a corrected spectrum more efficiently using the spectrometer's processing unit.

[0057] In one embodiment, the creation of a correction function (330) involves creating a synthesized imaging matrix (e.g., an imaging function) based on the recorded reference spectrum, which simulates the effect of one or more imaging errors on the spectra recorded by the spectrometer, and calculating a matrix inverse to the synthesized imaging matrix, which forms the correction function. The synthesized imaging function can, for example, represent a matrix with the spectral intensity distribution of the recorded reference spectrum. Since the recorded reference spectrum is based on a narrowband radiation source, the synthesized imaging function can be interpreted as a point spread function. A point spread function simulates, for example, the effect of one or more imaging errors on the spectra recorded by the spectrometer. In this case, for example,The inverse point spread function is the correction function. This correction function is designed, for example, to deconvolution the recorded spectrum of the spectrometer to obtain a corrected spectrum. This correction function increases the spectral resolution of the spectrometer and allows for the reduction of tolerances in the spectrometer's optical components, as the correction function minimizes the influence of optical aberrations on the corrected spectrum. Thus, regardless of the spectrometer's own aberrations, the correction function computationally reduces their influence on the recorded spectrum.

[0058] In one embodiment, the reference radiation source for recording the reference spectrum 320 comprises a laser or a narrowband radiation source. Thus, for example, a laser or a narrowband radiation source is provided as the reference radiation source 310. The peak of the narrowband reference radiation source should, for example, have a smaller spectral width than the spectral resolution of the spectrometer. The reference radiation source, which comprises a laser or a narrowband radiation source for recording the reference spectrum, provides, for example,The acquired reference spectrum provides information about the spectrometer's imaging errors, allowing a correction function to be created from the reference spectrum. This correction function can then be applied to acquired spectra to obtain corrected spectra that are less affected by imaging errors in the spectrometer's optical system. Thus, the laser or narrowband radiation source enables the correction function to be applied to unknown acquired spectra, thereby reducing the influence of imaging errors and generating a corrected spectrum that increases the spectrometer's resolving power.

[0059] In one embodiment, the spectral analysis system is impaired by imaging errors in the beam-shaping or imaging optics of the system. This impairment results in a loss of spectral resolution in the recorded spectra. The method can reduce or compensate for this loss of resolution.

[0060] Fig. Figure 13 shows a block diagram of an embodiment of a method 300 for determining a correction function for image correction of a spectrum recorded by a spectrometer and of a method 302 for applying the correction function. The method 300 and the method 302 are described in Fig. Although shown in a block diagram with successive steps, it is equally possible that procedure 300 is carried out independently of procedure 302 and procedure 302 independently of procedure 300.

[0061] The procedure 300 comprises providing 310 a narrowband radiation source, recording 320 the signal from the narrowband radiation source with the spectrometer, storing 344 the associated data, and deriving and storing a correction function 335. Storing 344 the associated data includes, for example, storing the environmental conditions in memory, but it can also include, for example, storing the recorded signal. The recorded signal can be stored, for example, as a spectral intensity distribution. Associated data can also include, for example, statistical information such as the designation / numbering of the narrowband radiation source, or system-relevant information such as error messages. Step 335, deriving and storing a correction function, can, for example,the same functionality as creating 330 a correction function from the recorded reference spectrum and storing 340 the correction function in a memory, as in . Fig. 12 shown, exhibit.

[0062] Method 302 comprises recording 370 a spectrum of an arbitrary sample and correcting 380 the spectrum (the recorded spectrum) by applying the correction function to the recorded spectrum (e.g., "convolution" or "inverse convolution"). Correcting 380 of the spectrum, for example, produces a corrected spectrum. The correction 380 of the spectrum is performed, for example, by a processing unit of the spectrometer (the spectral apparatus).

[0063] Methods 300 and 302, for example, allow the spectral resolution of a spectral instrument with imaging errors (including defocus) to be increased computationally, i.e., without interfering with the system's opto-mechanical hardware. This opens up the possibility of completely dispensing with the usual adjustment process in the future when building spectral instruments, especially in very large quantities and very small systems, and / or of no longer correcting certain imaging errors, thus relaxing tolerances and significantly reducing costs. For example, imaging errors are deliberately accepted, the effect of which on the resolution is corrected retrospectively in the signal (spectrum).

[0064] According to method 302, the recorded signal or spectrum of any sample is subsequently processed, thereby improving the spectral resolution of the spectrometer. A fundamental prerequisite for implementing such a mathematical method is prior knowledge of the intensity distribution of the spectrally split radiation in the focal plane of the beam path, which is subject to (imaging) errors (even defocus can be considered an imaging error). The correction method therefore consists, for example, of two essential steps: 1. the one-time formulation and determination of a correction function 300, and 2. the application 302 of this correction function to the measurement data of any spectral measurement. It is important that the determination 300 of the correction function can be performed only once, preferably during the commissioning of the instrument. The correction process can be directly implemented in the spectrometer's hardware.

[0065] Methods 300 and 302 for increasing spectral resolution and the associated computational effort can be optimized by incorporating a data storage unit into the spectrometer's electronics, where the data from recorded spectra can be stored. This applies, for example, to both the correction function and the recorded spectra of various samples. Furthermore, part of the spectrometer's electronics can be designed such that the necessary calculations are directly implemented, for example, in an FPGA (Field Programmable Gate Array) or DSP (Digital Signal Processor). This allows the spectrometer to provide pre-corrected spectra for further use in other instruments with minimal time and cost.

[0066] At this point, it should be emphasized once again that the described methods 300 and 302 can not only serve to avoid adjustment efforts, but also to greatly simplify optical aberration correction. For example, it is no longer necessary to correct certain image errors, such as spherical aberration. The residual errors are incorporated into the correction function. This generally reduces the tolerances of both the optical components and the assembly of the spectrometer. In this sense, the use of methods 300 and 302 can be considered Fig. 13 and the procedure presented in Fig. 12 to a modified optical design strategy in which certain errors are corrected in favor of others, or indeed not corrected.

[0067] The spectrometer and associated methods described herein are based, among other things, on the realization that the economical production of spectrometers in medium to large quantities or very small form factors is not possible with currently used methods; however, such production is achievable using the correction method 302 described above, i.e., computationally with signal processing. In this respect, the present invention forms the basis for the volumetric production of spectrometers, which in turn leads to entirely new fields of application that were previously inaccessible to spectroscopy.

[0068] The spectrometer and method described herein can be described in other words by the following exemplary embodiments.

[0069] According to one embodiment, the system (spectrometer) and method for performing spectral analytical measurements comprise: • An optical system for the spectral splitting of electromagnetic radiation; • At least one detector for detecting electromagnetic radiation; • Electronics for controlling / reading out at least one detector (e.g., first electronics); • Electronics for processing / preparing measurement data or signals from the detector (e.g., second electronics or, in other words, the processing unit); and • A data storage device.

[0070] The optical system for spectral splitting may have optical aberrations, and the data storage may contain data about the type of optical aberrations.

[0071] In one embodiment, the electronics for processing / preparing (second electronics) of measurement data can access the data in the data storage about the type of imaging errors for the purpose of manipulating / further processing the measurement data.

[0072] The data on optical imaging errors that the data storage device exhibits can, for example, be in the form of detector signals that may be correlated with the imaging errors.

[0073] The data on optical imaging errors in the data storage can be used to improve the spectral resolution.

[0074] In one embodiment, the defining optical aberration is defocus, and the associated aberration data stored in the data memory can be used to improve the spectral resolution. The defining optical aberration can also be, for example, defocus and / or spherical aberration and / or coma and / or astigmatism, or a combination of these aberrations and their associated data stored in the data memory, and can be used to improve the spectral resolution.

[0075] In one embodiment, the system for spectral splitting of electromagnetic radiation can be designed as a monochromator or polychromator or as a device for hyperspectral imaging.

[0076] The detector for electromagnetic radiation can have a plurality of detector elements.

[0077] In one embodiment, the spectrometer (system) can have a sensor for measuring the temperature and a data storage device in which the data for different temperatures are stored.

[0078] The manipulation / further processing of measurement data using data from the data storage can be carried out with an algorithm or a correction function that is implemented in part of the spectrometer's electronics.

[0079] The spectrometer can optionally have an integrated radiation source for electromagnetic radiation.

[0080] Optionally, the spectrometer can be integrated into a mobile device. Part of the device's electronics can be used to manipulate / further process the measurement data.

[0081] In one embodiment, a method for improving the spectral resolution of the spectrometer is created with the following steps: • Providing a narrowband radiation source (reference source) for electromagnetic radiation • Recording the narrowband spectrum of the radiation source with the spectrometer in the form of a detector signal as a function of the wavelength or wavenumber or frequency of the radiation • Storing the detector signal data in the data memory • Creating a correction function from the recorded data • Recording a spectrum of any sample • Application of the correction function to the recorded spectrum of the sample to improve the spectral resolution

[0082] In one embodiment, it may be sufficient to determine the correction function only once and write the associated data to memory.

[0083] The correction function can be determined using electromagnetic radiation that has a small spectral bandwidth compared to the spectral resolution of the spectral apparatus.

[0084] The data on the imaging errors are available, for example, as a spectral intensity distribution.

[0085] The correction function can optionally be determined at several points in a spectrum, and the associated data can be stored in the data memory.

[0086] The application of the correction function may involve mathematical convolution or inverse convolution, or a Fourier or inverse Fourier transformation.

[0087] The correction function can differ for different areas of a spectrum.

[0088] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, such that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device. Some or all of the process steps can be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the key process steps can be performed by such an apparatus.

[0089] Depending on specific implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be carried out using a digital storage medium, for example, a floppy disk, DVD, Blu-ray disc, CD, ROM, PROM, EPROM, EEPROM, FLASH memory, hard disk, or other magnetic or optical storage medium, on which electronically readable control signals are stored. These control signals can interact with, or interact with, a programmable computer system in such a way as to execute the respective method. Therefore, the digital storage medium can be computer-readable.

[0090] Some embodiments according to the invention therefore include a data carrier which has electronically readable control signals which are able to interact with a programmable computer system in such a way that one of the methods described herein is carried out.

[0091] In general, embodiments of the present invention can be implemented as a computer program product with a program code, wherein the program code is effective in carrying out one of the methods when the computer program product runs on a computer.

[0092] The program code can also be stored on a machine-readable medium, for example.

[0093] Other embodiments include the computer program for carrying out one of the methods described herein, wherein the computer program is stored on a machine-readable medium.

[0094] In other words, an embodiment of the method according to the invention is thus a computer program that includes program code for carrying out one of the methods described herein when the computer program runs on a computer.

[0095] Another embodiment of the methods according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for carrying out one of the methods described herein is recorded. The data carrier, the digital storage medium, or the computer-readable medium is typically tangible and / or non-perishable or non-temporary.

[0096] Another embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or sequence of signals can be configured, for example, to be transferred via a data communication connection, such as the Internet.

[0097] Another embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to perform one of the methods described herein.

[0098] Another embodiment comprises a computer on which the computer program for performing one of the procedures described herein is installed.

[0099] Another embodiment of the invention comprises a device or system designed to transmit a computer program for carrying out at least one of the methods described herein to a receiver. The transmission can be, for example, electronic or optical. The receiver can be, for example, a computer, a mobile device, a storage device, or a similar device. The device or system can, for example, include a file server for transmitting the computer program to the receiver.

[0100] In some embodiments, a programmable logic device (for example, a field-programmable gate array, an FPGA) can be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array can interact with a microprocessor to perform one of the methods described herein. Generally, in some embodiments, the methods are performed by any hardware device. This can be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0101] The devices described herein can be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0102] The devices described herein, or any components of the devices described herein, may be implemented at least partially in hardware and / or in software (computer program).

[0103] The methods described herein can be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0104] The methods described herein, or any components thereof, may be executed at least partially by hardware and / or by software.

[0105] The embodiments described above merely illustrate the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be obvious to other people skilled in the art. Therefore, it is intended that the invention be limited only by the scope of protection set forth in the following claims and not by the specific details presented herein by way of description and explanation of the embodiments.

Claims

[1] Spectral analysis system for recording a spectrum with optics that form a beam path, wherein the spectral analysis system is designed to apply a correction function, which is in the form of a matrix, to a recorded spectrum by means of matrix multiplication in order to obtain a modified spectrum, where the matrix is ​​an inverse of a matrix that distributes each spectral sample of an actual or undisturbed spectrum with a certain impulse response to the spectrally corresponding sample and the spectrally surrounding samples of a simulated recorded spectrum, and accumulates the contributions thus obtained for all samples of the simulated recorded spectrum, where the impulse response is determined by measuring a spectrum of a reference radiation source. [2] Spectral analysis system according to claim 1, wherein the correction function is generated by one of methods 13 to 22. [3] Spectral analysis system according to claim 1 or claim 2, configured to perform matrix manipulation when applying the correction function. [4] Spectral analysis system according to claim 3, wherein the matrix manipulation comprises matrix multiplication. [5] Spectral analysis system according to any one of claims 1 to 4, designed to determine and / or apply the correction function depending on an environmental condition of the spectral analysis system. [6] Spectral analysis system according to any one of claims 1 to 5, wherein the spectral analysis system comprises the following elements: an optical system comprising the optics, wherein the optical system is designed to spectrally split electromagnetic radiation and wherein the optical system is a monochromator, a polychromator or a device designed to perform hyperspectral imaging, and at least one detector element designed to detect the electromagnetic radiation split by the optical system. [7] Spectral analysis system according to claim 6, with inlet and outlet openings that are round, oval, rectangular, crescent-shaped, arcuate, square cushion-shaped or square barrel-shaped. [8] Spectral analysis system according to any one of claims 1 to 7, wherein the spectral analysis system comprises an optical system with optics and is designed to spectrally split electromagnetic radiation, and comprises at least one detector element designed to detect the electromagnetic radiation split by the optical system, and wherein the optical system has no adjustment elements, and / or wherein the optical system has no mechanical actuators to correct imaging errors after or during the manufacture of the spectral analysis system, and / or wherein an entrance aperture, an exit aperture and components of the optical system are fixed relative to each other and without adjustment. [9] Spectral analysis system according to any one of claims 1 to 8, wherein the correction function is stored in the spectral analysis system. [10] Spectral analysis system according to any one of claims 1 to 9, comprising a memory for storing the correction function, and / or a processing unit for performing calculations concerning the application of the correction function, and / or a sensor element for detecting an environmental condition. [11] Mobile device in which a spectral analysis system according to any one of claims 1 to 10 is integrated. [12] Mobile device according to claim 11, wherein electronics of the mobile device for the spectral analysis system perform a storage of the correction function and / or recorded spectra, calculations relating to the application of the correction function to the recorded spectrum and / or an environmental condition measurement and / or store the spectrum changed by the application of the correction function. [13] Method for determining a correction function for a spectrum recorded by a spectral analysis system, comprising: Recording a spectrum of a reference radiation source with the spectral analysis system to obtain an impulse response, wherein the spectrum of the reference radiation source has a peak with a spectral width smaller than the spectral resolution of the spectral analysis system. Creating a correction function based on the impulse response, so that when the correction function is applied to recorded spectra acquired by the spectral analysis system, modified spectra are obtained that are less affected by errors in the optics of the spectral analysis system. where the correction function is in the form of a matrix, and where the matrix is ​​an inverse of a matrix that distributes each spectral sample of an actual or undisturbed spectrum with a certain impulse response to the spectrally corresponding sample and the spectrally surrounding samples of a simulated recorded spectrum, and accumulates the contributions thus obtained for all samples of the simulated recorded spectrum. [14] Method according to claim 13, wherein the spectral analysis system is impaired by imaging errors of a beam-shaping or imaging optic of the spectral analysis system, the impairment consisting of a spectral resolution loss of the recorded spectra. [15] Method according to claim 13 or 14, wherein the spectral analysis system is according to any one of claims 1 to 11. [16] Method according to any one of claims 13 to 15, wherein the acquisition with one or more reference spectra is carried out one or more times, wherein the one or more reference spectra together have several peaks whose spectral width is each smaller than the spectral resolution of the spectral analysis system, and which have a different spectral position to obtain a plurality of acquired impulse response spectra, wherein the creation of a correction function is carried out on the basis of the plurality of impulse response spectra. [17] Method according to any one of claims 13 to 16, wherein the reference spectrum is recorded under different environmental conditions in order to create a correction function for each environmental condition. [18] Method according to any one of claims 13 to 17, wherein the correction function is stored in a memory together with information on the associated environmental conditions, from which the spectral analysis system obtains knowledge of the correction function. [19] Method according to any one of claims 13 to 18, wherein the creation of the correction function comprises creating a synthesized imaging function based on the recorded reference spectrum, which simulates an effect of one or more imaging errors on the spectra recorded by the spectral analysis system, and calculating a function inverse to the synthesized imaging function. [20] Method according to any one of claims 13 to 18, wherein the creation of the correction function comprises creating a synthesized imaging matrix based on the recorded reference spectrum, which simulates an effect of one or more imaging errors on the spectra recorded by the spectral analysis system, and calculating a matrix inverse to the synthesized imaging matrix, which forms the correction function. [21] Method according to any one of claims 13 to 20, wherein the creation and / or application of the correction function is iterative or non-iterative. [22] Method according to any one of claims 13 to 21, wherein the reference radiation source for recording the reference spectrum comprises a laser or a narrowband LED or a narrowband thermal radiation source or a line emitter. [23] Computer program comprising program code for carrying out the method according to any one of claims 13 to 22, when the program runs on a processor.

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