Optical filter arrangement with transmission spectrum the intensity of which can be continuously adjusted, and corresponding measurement device

Abstract

The invention relates to an optical filter arrangement (30) for filtering an incident beam bundle (15). The optical filter arrangement (30) comprises a filter (10) which is designed as a bandpass filter which is variable over a spectrum and which is equipped with at least one shading means (31). According to the invention, the shading means (31) is designed to adjust an overall transmission spectrum (20) of the filter (10). To this end, the shading means (31) is designed to shade at least a portion of the filter (10) optically in a specifiable manner and / or to switch same to a non-transparent state. The invention also relates to a method (100) for determining a physical or chemical variable of a substance sample (16) which is examined using such an optical filter arrangement (30), and to a corresponding computer program product (60). In addition, the invention relates to a measurement device (70) equipped with such an optical filter arrangement (30). The invention furthermore relates to a simulation method (200) for simulating an operating behaviour of a corresponding optical filter arrangement (30), and to a corresponding simulation program product (70).

Description

[0001] Description

[0002] Optical filter arrangement with continuously adjustable transmission spectrum and corresponding measuring device

[0003] The invention relates to an optical filter arrangement by means of which the intensity of a transmission spectrum can be continuously adjusted. The invention also relates to a measuring device having such an optical filter arrangement. Furthermore, the invention relates to a method for determining a physical or chemical quantity of a substance sample and a computer program product configured for this purpose. Furthermore, the invention relates to a simulation method for such an optical filter arrangement and a corresponding simulation program product.

[0004] European patent application EP 0 205 050 A2 discloses a photometer for simultaneously measuring multiple wavelengths. The photometer has a circularly variable filter to which pivoting radial arms are attached. Opposite optical fibers are attached to the ends of the radial arms. Light emitted from one optical fiber passes through the circularly variable filter and reaches the opposite optical fiber. The light is then guided to a detection means. By adjusting the positions of the radial arms, a plurality of wavelengths can be detected simultaneously.

[0005] Measuring instruments such as photometers are used in a wide variety of analytical applications. The objective is to quickly and precisely determine the physical or chemical properties of a sample or the composition of increasingly complex samples. Among other things, the aim is to simultaneously measure an increased number of sample components. Furthermore, the objective is for such photometers to be compact, simple, and cost-effective. The invention is based on the task of providing a method that offers an improvement in at least one of the aspects outlined.

[0006] The object described above is achieved by a measuring device according to the invention which comprises a detector and an optical filter arrangement. The optical filter arrangement and the detector are coupled to an evaluation unit. The evaluation unit can be designed as a single device or as a plurality of devices which interact with one another. The optical filter arrangement according to the invention is designed to filter an incident beam of rays. The beam of rays can be generated in a measuring cell in which a material sample is irradiated and as a result the incident radiation is scattered and / or absorbed, for example inelastically, by the material sample. As a result, the beam of rays to be filtered by the optical filter arrangement is emitted from the measuring cell. The optical filter arrangement comprises a filter which is designed as a bandpass filter which is variable over a spectrum.The filter is therefore transparent to the beam of rays at different wavelength intervals, i.e. partial spectra, depending on a position on the filter. The filter can be transparent to a specific partial spectrum in sections, i.e. have a corresponding partial transmission spectrum. The partial transmission spectra that are present at different positions on the filter in turn combine to form an overall transmission spectrum. The optical filter arrangement further comprises a shading means. The shading means can be arranged in front of or behind the filter, viewed along a beam path of the beam of rays. According to the invention, the shading means is designed to set the overall transmission spectrum of the filter in a predeterminable manner, for example in terms of intensity.Furthermore, the shading means is designed to provide and / or make non-transparent at a predeterminable position and / or a predeterminable section. Accordingly, the overall transmission spectrum of the filter, and thus of the optical filter arrangement, can be precisely adjusted for measuring operation, for example in a photometer. The overall transmission spectrum can be adapted, among other things, to a detector which is designed to receive and record the overall transmission spectrum. As a result, for example, the intensity present in a partial transmission spectrum can be reduced to such an extent that the detector is not oversaturated. Consequently, the technical potential of a detector can be fully exploited and increased measurement accuracy can be achieved across a broad spectrum. Likewise, the use of multiple detectors which are set up for measuring operation in different intensity ranges can be avoided.The detector can, for example, be designed as a single-element detector. The optical filter arrangement thus allows an associated measuring device, such as a photometer, to be manufactured compactly, simply, and cost-effectively. The optical filter arrangement itself can also be manufactured easily. Furthermore, the detector can be designed to detect a partial transmission spectrum of the optical filter arrangement. The partial transmission spectrum forms a section of the overall transmission spectrum of the filter.

[0007] In addition, the evaluation unit can be equipped with a computer program product which is designed according to one of the embodiments outlined below. The evaluation unit can also be designed as a control unit for actuating the optical filter arrangement. The measuring device can also be designed, for example, as a photometer, in particular as a Raman photometer. Such a measuring device makes it possible to determine a plurality of physical or chemical parameters of a material sample and / or to quickly determine the composition of the material sample from a plurality of components. The features of the optical filter arrangement, the method and the computer program product described above can be transferred individually or in combination to the claimed measuring device.In one embodiment of the claimed measuring device, and thus of the claimed optical filter arrangement, the shading means is designed as a display having a plurality of pixels. Such a display can be, for example, a liquid crystal display, also called an LCD. At least one of the pixels can be switched to be predeterminably transparent or non-transparent. The display itself can be transparent in a basic state and comprise at least one pixel that can be switched to be non-transparent. The display can thus be switched to be transparent or non-transparent pixel by pixel. Alternatively, the display can be non-transparent in a basic state and comprise at least one pixel that can be switched to be predeterminably transparent. Furthermore, the at least one pixel can be switched to be partially transparent or partially non-transparent in a stepped or continuous manner.Consequently, by appropriately switching at least one pixel of the display, it is possible to locally specify the intensity of at least a partial transmission spectrum of the filter or how the intensity is distributed in its overall transmission spectrum. The display can therefore be controlled pixel by pixel and can therefore adapt the intensity of at least a partial transmission spectrum of the filter. By means of pixels that can be switched to be partially transparent or partially opaque in a stepped or continuous manner, the intensity of at least a partial transmission spectrum of the filter, i.e. a degree of transparency of the filter, can be adjusted even more precisely. Furthermore, it is possible to specify which areas of a detector, which receives at least a partial transmission spectrum of the filter, are irradiated and with which intensity. This means, for example, that adjacent sections on the filter which are transparent to different spectra can be separated on the detector.This avoids overlaps. The detector can also have a reduced resolution compared to known detectors in photometers. Overall, the claimed optical filter arrangement further simplifies a corresponding measuring device and makes it more cost-effective. Furthermore, the display can be tilted so that the beam of rays hits it at an angle other than 90°. By tilting the display in this way, a reduced area per pixel can be made opaque, partially transparent or partially opaque, thereby increasing the achievable resolution of the display. Accordingly, the section to be covered by the display can be precisely adjusted and the optical filter arrangement is also suitable for precision-oriented applications, for example laboratory technology. The shading means designed as a display can be positioned in front of or behind the filter along the direction of propagation of the beam of rays.Furthermore, the shading device designed as a display can also be switched to be transparent, non-transparent, partially transparent, or partially non-transparent, column by column or row by row. Wiring of the pixels column by column or row is easy to implement. This allows the shading device to be easily tuned and, among other things, a scanning function can be provided across the entire transmission spectrum of the filter. This also increases the functional versatility of the optical filter arrangement.

[0008] In a further embodiment of the claimed measuring device, and thus also of the claimed optical filter arrangement, the filter is designed at least in sections as a continuously variable bandpass filter. Accordingly, a transparent spectrum of the filter shifts continuously along a direction on the surface of the filter in the corresponding section. The filter can be designed continuously as a variable bandpass filter, which allows the use of a broad spectral range. The optical filter arrangement is thus suitable for a wide variety of applications. Alternatively, in the case of a filter that is only designed in sections as a continuously variable bandpass filter, an unused spectral range can be excluded, i.e. skipped. The filter can thus be designed as required.The filter can, for example, be designed as a combination of several continuously variable bandpass filters. The continuously variable bandpass filter can, for example, be produced using an inkjet printing process. For example, the continuously variable bandpass filter can be designed as a linearly variable bandpass filter or as a circularly variable bandpass filter. The linearly variable bandpass filter can be essentially rectangular and have a transparent spectrum that is essentially variable along one of its edges. Correspondingly, the circularly variable bandpass filter can have a variable transparent spectrum essentially along a circumferential direction. Continuously variable bandpass filters of this type make it possible to precisely specify at least one desired partial transmission spectrum. In conjunction with a display with at least one pixel that is predefinably transparent or...is switchable to be non-transparent, the accuracy with which the desired partial transmission spectrum can be selected is essentially limited by the resolution, i.e. the pixel size, of the display. Accordingly, the achievable precision with the claimed optical filter arrangement is higher, the higher the resolution of the display. Technical advances in terms of resolution in displays can therefore be easily transferred to the claimed optical filter arrangement. By replacing the display with a higher resolution display, the claimed optical filter arrangement can be easily retrofitted and improved. Furthermore, continuously variable bandpass filters make it easy to separate transparent and non-transparent sections of the filter and thus receive sharply selected partial spectra at a detector.

[0009] Furthermore, the claimed measuring device, and thus also the claimed optical filter arrangement, can be provided with a polarization filter. The polarization filter can be positioned in the beam path of the beam, i.e., in front of or behind the filter. Since a shading device designed as a display, in particular as an LCD, itself acts as a polarization filter, the overall intensity of the overall transmission spectrum can be further adjusted using the polarization filter. This further increases the discriminatory power of different partial transmission spectra on a detector that receives at least the partial transmission spectrum of the optical filter arrangement.

[0010] The object described at the outset is also achieved by a method according to the invention for determining a physical or chemical parameter of a material sample. The physical or chemical parameter can be, for example, a density of the material sample, its calorific value, its Wobbe index, its structural makeup, a parameter relating to a light-induced degradation of at least one component of the material sample, a parameter relating to a course of a chemical reaction in the material sample or a mixture ratio. The method is carried out using an optical filter arrangement and comprises a first step in which the material sample is irradiated with a light source. The light source can be a laser, for example. By irradiating the material sample, a beam of rays is generated in the first step and is emitted by the material sample.The method further comprises a second step in which a target intensity for at least a partial spectrum of the beam is specified. The specification can be made by a user and / or a computer program product with which the physical or chemical variable is to be determined. The computer program product can for this purpose comprise artificial intelligence. Furthermore, in the second step, a switching signal is output to at least one pixel by means of which its degree of transparency is specified, i.e. at least a partial transmission spectrum of a filter of the optical filter arrangement is set in terms of intensity. The switching command can be determined based on the target intensity for the partial spectrum of the beam.

[0011] The claimed method also includes a third step in which at least a partial transmission spectrum of the filter is recorded, which at least partially overlaps with the partial spectrum of the beam according to the second step. The partial transmission spectrum can be recorded using a detector that can be arranged behind the optical filter arrangement. This specifies the overall intensity of the recorded partial transmission spectrum, for example that received by the detector. In a fourth step, the physical or chemical parameter of the material sample is determined based on the partial transmission spectrum recorded in the third step. The method according to the invention offers an increased degree of measurement accuracy and can be implemented essentially without delay.The physical or chemical quantity to be determined can be determined by detecting the beam of rays, which propagates essentially at the speed of light. The speed at which the physical or chemical quantity is determined is limited at most by the reaction speeds of the optical filter arrangement and its associated detector and the computing speed of an associated evaluation unit. Accordingly, the claimed method offers an increased sampling rate, which can be increased even further through future advances in computing power and pixel control speed. Furthermore, the claimed method requires a reduced number of detectors and can, for example, be carried out with just one detector. This also makes the use of a cost-intensive single-element detector as the detector efficient and space-saving.

[0012] The claimed method can be carried out, for example, using a measuring device outlined above, in particular a measuring device with an optical filter arrangement according to one of the embodiments presented above. The technical advantages of the corresponding measuring device or the corresponding optical filter arrangement are thus also present in the claimed method. The features of the claimed measuring device and, accordingly, of the claimed optical filter arrangement are transferable to the claimed method individually and in combination.

[0013] In a further embodiment of the claimed method, the at least one pixel of the display can be switched with a predeterminable clocking in the second step. For example, the at least one pixel can be switched alternately transparent and non-transparent in a clocked manner. The at least one pixel can be switched in a clocked manner using pulse width modulation, for example. Alternatively or additionally, the at least one pixel can be switched in a clocked manner, stepped or continuously between different degrees of transparency. By clocked control of the at least one pixel, at least one partial transmission spectrum of the filter can be adjusted even more finely in terms of intensity. Furthermore, pixels of the display can be switched transparent or non-transparent in such a way that predeterminable partial transmission spectra are generated.Accordingly, targeted serial measurement of different physical or chemical parameters and / or different components of the sample is possible. Accordingly, the claimed method offers a high degree of flexibility and is adaptable to a wide variety of different measurement methods. The claimed method can be retrofitted, in particular, to existing measuring devices, such as photometers.

[0014] Furthermore, the claimed method can comprise a plurality of pixels being switched to be opaque, transparent, partially transparent or partially opaque in a row or column manner. This provides a movable search area. In particular, at least one row and / or column of pixels can be switched to be at least partially transparent. At the same time, pixels outside the search area can be switched to be opaque. The search area can be moved in a predetermined manner via the display and thus via the filter. This makes the optical filter arrangement tunable, i.e. a spectral sweep is realized. This expands the functional spectrum of a measuring device with a corresponding optical filter arrangement. Furthermore, the second, third and fourth steps of the claimed method can be carried out for a plurality of partial spectra, each with a desired intensity.Accordingly, a plurality of partial transmission spectra of the filter can be specifically specified, on the basis of which a physical or chemical parameter of the material sample can be determined, either individually or in combination with another partial transmission spectrum. Alternatively or additionally, the composition of the material sample can be precisely determined, for example by essentially simultaneously determining the concentrations of different components. Overall, the claimed method can be used to determine a plurality of physical or chemical parameters of the material sample in parallel, or to quickly determine the composition of a complex material sample. The versatility of the claimed method is essentially only limited by the pixel control speed, the resolution of the detector used, and the computing power of an associated evaluation unit.Furthermore, partial transmission spectra that are irrelevant for the intended determination of the physical or chemical parameter can be completely shaded and thus excluded from further computational analysis. Accordingly, only minimal data is generated in these partial spectra. The claimed method is thus particularly data-efficient, which further facilitates rapid computational processing.

[0015] The underlying problem is similarly solved by a computer program product according to the invention which is designed to control an optical filter arrangement comprising a filter. The computer program product is designed to output control signals for actuating a shading means of the optical filter arrangement. The shading means is arranged in the beam path of the optical filter arrangement, i.e. in front of or behind a filter of the optical filter arrangement. According to the invention, the computer program product is designed to carry out a method according to at least one of the embodiments outlined above. The computer program product can further be designed to receive and evaluate measurement signals from at least one detector which is designed and arranged to receive at least a partial transmission spectrum of the optical filter arrangement.The computer program product can furthermore be stored in an executable manner, at least in part, on an evaluation unit which is directly or indirectly coupled to the detector and also serves as a control unit for the optical filter arrangement. Furthermore, the computer program product can be embodied as software, hard-wired, i.e. as a chip, integrated circuit or FPGA, or as a combination thereof. Furthermore, the computer program product can be embodied monolithically, i.e. can be executable on a single hardware platform. Alternatively, the computer program product can be embodied modularly, i.e. can comprise a plurality of subprograms which interact via a communicative data connection and thereby implement their functionality.

[0016] The problem described above is also solved by a method according to the invention for simulating the operating behavior of an optical filter arrangement. The operating behavior can comprise determining a partial transmission spectrum and / or a total transmission spectrum of the optical filter arrangement. The operating behavior can be simulated under predefinable operating parameters. The method comprises a first step in which a data set is provided which at least partially simulates the functioning of at least one section of the optical filter arrangement to be simulated. The data set can comprise a model of the optical filter arrangement which at least partially depicts its structure. Alternatively or additionally, the data set can also be designed as a computer model which simulates the functioning of the optical filter arrangement.The mode of operation here is to be understood as any interaction of the optical filter arrangement with a beam of rays incident on it, and accordingly a virtual representation of such a beam of rays. The method further comprises a second step in which at least one operating parameter is specified which defines the operating behavior to be simulated. The operating parameter includes, for example, a composition of the material sample, a partial spectrum or a total spectrum of the beam of rays, its intensity, a degree of collimation of the beam of rays, a resolution of a detector, a switching behavior of at least one pixel and / or a position of a shading means, in particular a covering surface. The operating parameter can essentially be any value that is not unchangeable due to the design of the optical filter arrangement to be simulated.The operating behavior can include a partial transmission spectrum and / or a total spectrum of the optical filter arrangement that develops when it is irradiated by the beam. The operating behavior can also include the measurement behavior of a detector positioned behind the optical filter arrangement.

[0017] The method further comprises a third step in which a simulation program product is executed which is designed to determine at least one performance parameter of the optical filter arrangement based on the data set specified in the first step and the at least one operating parameter specified in the second step. The performance parameter can essentially be any variable by which the operating behavior of the optical filter arrangement can be quantified. In particular, it can be an intensity distribution in a partial transmission spectrum or in the overall transmission spectrum of the optical filter arrangement. Likewise, a position of partial transmission spectra can be mapped on a receiver of the associated detector, for example a CCD chip or photon multiplier, in the form of at least one performance parameter.Furthermore, the method according to the invention includes a fourth step in which the at least one performance parameter determined in the third step is output. The output is made to a user, for example, via a graphical user interface and / or via a data interface. The at least one performance parameter can be transferred to other simulation-oriented computer programs via the data interface.

[0018] According to the invention, the optical filter arrangement which is simulated using the method is designed according to one of the embodiments presented above. Alternatively or additionally, the method for simulating the optical filter arrangement is set up to simulate an operating method according to one of the embodiments outlined above. The optical behavior of filter elements, for example bandpass filters, can be precisely simulated with relatively little computational effort. The shading behavior on such a filter element or on such a filter is essentially determined by a geometric resolution which the underlying data set has. The geometry relevant for an optical behavior can also be simulated with relatively little computational effort.In particular, the data set can comprise an essentially planar, i.e. two-dimensional, model of the filter with its filter elements, which is provided with a grid and can thus be shaded or made non-transparent in a predetermined manner using the grid. The invention is based, among other things, on the surprising finding that the underlying optical filter arrangement is particularly simulation-friendly due to its design. Accordingly, the operation of the optical filter arrangement can be reproduced quickly and precisely. The claimed method can be designed to monitor the operation of a corresponding optical filter arrangement. For this purpose, for example, a performance parameter determined in the third step can be compared with a corresponding measured value of the detector and thus checked for plausibility.Because the claimed method can be carried out quickly even on hardware platforms with relatively low computing power, the operation of the optical filter arrangement can be monitored with reduced delay. In particular, the claimed method can be used for real-time monitoring of the optical filter arrangement. Furthermore, intended operation of the optical filter arrangement can be quickly tested and optimized by simulation. Overall, the claimed method for simulating the operation of the associated optical filter arrangement enables accelerated error detection and / or the technical potential of the optical filter arrangement can be exploited more effectively in a simple manner. The features of the underlying filter arrangement and the underlying operating method can be easily transferred to the simulation method individually or in combination, and therefore also apply to their virtual representations therein.

[0019] The problem described at the outset is also solved by a simulation program product according to the invention. The simulation program product is designed to simulate the operating behavior of an optical filter arrangement. For this purpose, the simulation program product can be designed as a so-called digital twin of the optical filter arrangement, for example as a digital twin within the meaning of the application US 2017 / 0286572 A1. The disclosure content of US 2017 / 0286572 A1 is incorporated by reference into the present application. According to the invention, the simulation program product is designed to carry out a method for simulating an operating behavior according to one of the embodiments outlined above. Accordingly, the features of the associated method for simulation can be transferred to the simulation program product.

[0020] The invention is explained in more detail below with reference to individual embodiments in the figures. The figures are to be read as complementary to one another in that identical reference numerals in different figures have the same technical meaning. Furthermore, the individual features of the embodiments shown in the figures can also be combined with one another and with the features outlined above. They show in detail:

[0021] FIG 1 shows a schematic structure of a first embodiment of the optical filter arrangement according to the solution and an embodiment of the claimed simulation method;

[0022] FIG 2 shows a schematic structure of a second embodiment of the claimed optical filter arrangement and an embodiment of the claimed operating method;

[0023] FIG 3 is a schematic oblique view of a component of a third embodiment of the claimed optical filter arrangement.

[0024] FIG. 1 schematically shows a first embodiment of the optical filter arrangement 30 according to the solution. Likewise, an embodiment of the claimed method 200 for simulation, as the simulation method 200, is schematically depicted. The optical filter arrangement 30 comprises a filter 10 which is designed as a bandpass filter which is variable over a spectrum. The filter 10 comprises a plurality of filter elements 12 which are arranged adjacent to one another around a center point 13. The filter elements 12 are essentially shaped like a circular segment and together form the circular filter 10, which can be understood as a segment filter 26. Each of the filter elements 12 has a partial transmission spectrum 18 in which it is transparent for a specific wavelength 21 or a wavelength range. The partial transmission spectra 18 are designed differently and combined form an overall transmission spectrum 20 of the filter 10.The filter elements 12 are arranged along a circumferential direction 19, sorted according to their partial transmission spectra 18. The boundaries 14 of the total transmission spectrum 20 coincide with a common radial line of the filter 10. During measurement, a beam of rays 15 is incident on the filter 10, the beam of rays 15 being essentially circular and centered on the center point 13 of the filter 10.

[0025] The beam 15 is emitted by a material sample 16 having a composition 17 characteristic of an intensity distribution 41 with which the beam 15 is incident on the filter 10. The composition 17 of the material sample 16 represents a physical or chemical quantity that is to be determined during the measuring operation of the optical filter arrangement 30.

[0026] The filter 10 is provided with a shading means 31 in the region of a first filter element 12.1, a second filter element 12.2, and a third filter element 12.3. The shading means 31 are designed as cover surfaces 32 that are movable along a radial direction. A corresponding radial movement is represented in FIG. 1 by a double arrow 33. The cover surfaces 32 are each essentially wedge-shaped or shaped like a circular segment. A predeterminable portion of the first, second, or third filter element 12.1, 12.2, 12.3 can be shaded by the radial movement 33. Accordingly, an intensity 22 can be set for the corresponding filter element 12.1, 12.2, 12.3 in the region of its partial transmission spectrum 18.The further the cover surface 32 is moved toward the center point 13 of the filter 10, the stronger the shading effect and the lower the intensity 22 in the corresponding partial transmission spectrum 18. A position of the cover surfaces 32 can be specified during assembly of the optical filter arrangement 30. Alternatively, the cover surfaces 32 can each be designed to be movable independently of one another via a drive means and positioned before or during a measurement operation.

[0027] Accordingly, an intensity decrease 23 results in each area, i.e., a wavelength range, corresponding to the partial transmission spectrum 18 of the first, second, or third filter element 12.1, 12.2, 12.3. The intensity decrease 23 is related to an intensity 22 in this area that results when the beam 15 is incident on the filter 10 without shadow. The intensity decrease 23 is greater the further the corresponding filter element 12.1, 12.2, 12.3 is interconnected by the cover surface 32. During measurement operation of the optical filter arrangement 30, at least a partial transmission spectrum 34 of the filter 10, i.e., a section of its overall transmission spectrum 20, is detected by a detector 40. Due to the intensity reduction 23 at the second filter element 12.2, an intensity 22 is present at the corresponding wavelength 21, which can be easily detected and processed by the detector 40.Accordingly, the intensity 22 in the range of the partial transmission spectrum 18 of the second filter element 12.2 can be adjusted in such a way that, for example, overdriving or oversaturation of the detector 40 is avoided. An analogous effect is also achieved in the range of the partial transmission spectra 18 of the first and third filter elements 12.1, 12.3. The total transmission spectrum 20 of the filter 10 can therefore be detected with a single detector 40. A measuring device 50 equipped with such an optical filter arrangement 30 consequently requires a reduced number of detectors 40 to detect the displayed total transmission spectrum 20. Such a measuring device 50 can therefore be manufactured simply, compactly, and cost-effectively. To determine the composition 17 of the substance sample 16, the detector 40 is connected to an evaluation unit 45 via a communicative data connection 44.

[0028] With the illustrated optical filter arrangement 30, an embodiment of the claimed method 200 for simulating its operating behavior can be carried out. The method 200 starts with a first step 210 in which a data set is provided by which the functionality of a section of the optical filter arrangement 30 is at least partially simulated. The data set comprises at least a virtual representation of a filter element 12, 12.1, 12.2, 12.3. Furthermore, a second step 220 belongs to the claimed method 200 in which at least one operating parameter is specified which defines the operating behavior to be simulated. The operating parameter is the spectrum of the beam 15, the composition 17 of the material sample 16 emitting the beam 15 and / or at least one position of a cover surface 32.The method 200 further comprises a third step 230 in which a simulation program product 70 (not shown in detail) is executed. The simulation program product 70 is designed to determine at least one performance parameter of the optical filter arrangement 30 on the basis of the operating parameter and the data set. The performance parameter is the total transmission spectrum 20 which is established with its intensity distribution 41 when the beam bundle 15 is aligned with the filter 10 at the given position of at least one covering surface 32. The claimed method 200 further comprises a fourth step 240 in which the determined performance parameter, i.e. the resulting total transmission spectrum 20, is output to a user and / or a data interface 74 via a graphical user interface 72.The method 200 can be implemented with reduced computational effort and is therefore suitable for monitoring the optical filter arrangement 30, in particular for real-time monitoring.

[0029] A second embodiment of the claimed optical filter arrangement 30 is depicted in FIG 2. Likewise, an embodiment of the claimed method 100 for operating such an optical filter arrangement 30, i.e. an operating method 100, is shown schematically. The optical filter arrangement 30 comprises a filter 10 which is designed as a linearly variable filter 28. The filter 10 is essentially rectangular and, viewed along one of its edges, has a variable partial transmission spectrum 18. In FIG 1, the linearly variable filter 28 is transparent from left to right for partial transmission spectra 18 with increasing wavelength 21. The filter 10 is provided with a display 35 which has a plurality of pixels 36 which serve as shading means 31. The pixels 36 can each be switched in a stepped or continuously variable manner via a control unit 42.The pixels 36 can each be switched between a transparent state 37 and an opaque state 39. Likewise, the pixels 36 can each be switched to a predeterminable degree into a partially transparent state 38. Furthermore, the pixels 26 can be controlled independently by the control unit 42 via switching signals 43. For this purpose, the control unit 42 is equipped with a suitably designed computer program product 60. The optical filter arrangement 30 belongs to a measuring device 50, which also includes a detector 40 that interacts with the optical filter arrangement 30.

[0030] The optical filter arrangement 30 according to FIG 2 can be adjusted by means of a claimed method 100. The method 100, i.e. the operating method 100, starts from a first step 110 in which the optical filter arrangement 30 is provided in a functional state. Next, a material sample 16 is irradiated with a light source so that it emits a beam of rays 16. The beam of rays 15, i.e. its spectral composition, is characteristic of its composition 17. The beam of rays 15 emitted in the first step 110 falls on the filter 10. In a second step 120, a user and / or an artificial intelligence specifies a target intensity 25 for a partial spectrum 24 of the beam of rays 15. The existing intensity 22 is higher than the target intensity 25 in the corresponding partial spectrum 24. The current intensity 22 is determined and compared with the target intensity 25.Furthermore, in the second step 120, a switching signal 43 is determined for a plurality of pixels 26 of a display 35, with which switching signal their respective degree of transparency is specified. At least in the region of the partial spectrum 24 of the beam 15, a plurality of pixels 36 are switched to be opaque, thus reducing the transparent area in the region of the partial spectrum 24. The switching commands 43 are determined by means of a computer program product 60, which is stored executably on the control unit 42. By switching the plurality of pixels 36 to be opaque, an overall transmission spectrum 20 is obtained for the filter 10, which overall transmission spectrum 20 is reduced to different degrees in terms of intensity 22 in the range of different wavelengths 21.

[0031] Likewise, a third step 130 belongs to the claimed method 100, in which a partial transmission spectrum 34 of the filter 10 is detected. The detected partial transmission spectrum 34 overlaps with the partial spectrum 24 of the beam 15 in terms of wavelength 21. The detection of the partial transmission spectrum 34 is carried out by the detector 40. The total transmission spectrum 20, when detected by the detector 40, essentially represents an intensity characteristic curve 27, which has an intensity 22 for each wavelength 21 of the total transmission spectrum 20.

[0032] Furthermore, in a fourth step 140 of the claimed method 100, a physical or chemical parameter of the substance sample 16 is detected based on the detected partial transmission spectrum 34. For example, a concentration of a component in the composition 17 of the substance sample 16 is determined using the detected partial transmission spectrum 34 of the filter 10. The fourth step 140 is carried out by means of an evaluation unit 45, which is coupled to the detector 40 via a communicative data connection 44. The evaluation unit 44 can be functionally part of the control unit 42 or vice versa. Overall, the claimed method 100 can be carried out by means of the computer program product 60, which is stored executably on the control unit 42.By means of the claimed method 100, the display 35, and thus the optical filter arrangement 30, can be adapted to different spectra of beams 15 in such a way that the intensity 22 in a partial spectrum 24 of the beam 15 to be examined can be adapted to the detection capability of the detector 40. The partial spectrum 24 can essentially be freely predetermined. Accordingly, a single detector 40 is suitable for evaluating a wide range of possible beams 15, and thus different material samples 16. Because the display 20 can be switched to be transparent, partially transparent or non-transparent over essentially the entire total transmission spectrum 20 of the filter 10, a plurality of partial spectra 24 of the beam 15 can also be set as a separate partial transmission spectrum 34.As a result, a plurality of physical or chemical parameters of the material sample 16 can be determined essentially simultaneously. The optical filter arrangement 30 is represented by a simulation program product 70 (not shown in detail) and is designed to simulate the operating behavior of the optical filter arrangement 30 that occurs during the described method 100. The simulation program product 70 is designed as a digital twin of the optical filter arrangement 30.

[0033] A filter 10 according to a third embodiment of the claimed optical filter arrangement 30 is shown schematically in FIG 3. The filter 10 is essentially circular and has a variable partial transmission spectrum 18 along a direction of rotation 19. Along the direction of rotation 19, the filter 10 is transparent to a continuously increasing wavelength 21. Boundaries 14 of a total transmission spectrum 20 thus formed form a radial line on the filter 10, starting from its center point 13. Overall, the filter 10 forms a so-called circularly variable filter 29. The circularly variable filter 29 can be used analogously to a segment filter 26 as in FIG 1. Further alternatively or additionally, the circularly variable filter 29 can also be combined with a correspondingly designed display 25 as in FIG 2. The circularly variable filter 29 can be used in an optical filter arrangement 30 which belongs to a measuring device 50.Furthermore, the circularly variable filter 29 is represented in an associated simulation program product 70 with which its operating behavior can be simulated.

Claims

Patent claims 1. Measuring device (50) comprising a detector (40) and an optical filter arrangement (30) coupled to an evaluation unit (45), wherein the optical filter arrangement (30) is designed to filter an incident beam (15) and comprises a filter (10) which is designed as a bandpass filter variable over a spectrum and which is equipped with at least one shading means (31), wherein the shading means (31) is designed to adjust an overall transmission spectrum (20) of the filter (10) in order to optically provide at least a portion of the filter (10) in a predeterminable manner and to switch it non-transparent, characterized in that the shading means (31) is designed as a display (35), the pixels (36) of which can each be switched to be predeterminably transparent, partially transparent or non-transparent, and the detector (40) is arranged to detect at least one partial transmission spectrum (34) of the optical filter arrangement (30).

2. Measuring device (50) according to claim 1, characterized in that the display (35) is designed as a liquid crystal display.

3. Measuring device (50) according to claim 1 or 2, characterized in that the display (35) is arranged tilted.

4. Measuring device (50) according to one of claims 1 to 3, characterized in that the display (35) is arranged in front of or behind the filter (10) along a propagation direction of the beam (15).

5. Measuring device (50) according to one of claims 1 to 4, characterized in that the filter (10) is designed at least in sections as a continuously variable bandpass filter.

6. Measuring device (50) according to claim 5, characterized in that the continuously variable bandpass filter is designed as a linearly variable bandpass filter (28).

7. Measuring device (50) according to one of claims 1 to 6, characterized in that the optical filter arrangement (30) is provided with a polarization filter.

8. A method (100) for determining a physical or chemical quantity of a material sample (16) by means of an optical filter arrangement (30), comprising the steps of: a) irradiating the material sample (16) with a light source and generating a beam of rays (15) which is emitted by the irradiated material sample (16); b) specifying a target intensity (25) for at least one partial spectrum (24) of the beam of rays (15) and outputting a switching signal (43) to at least one pixel (36) for specifying its degree of transparency; c) detecting at least one partial transmission spectrum (34) which at least partially overlaps with the partial spectrum (24) from step b); d) determining the physical or chemical quantity of the material sample (16) based on at least the partial transmission spectrum (34).

9. Method (100) according to claim 8, characterized in that the method (100) is carried out by means of an optical filter arrangement (30) according to one of claims 1 to 7.

10. Method (100) according to claim 8 or 9, characterized in that the at least one pixel (36) is switched with a predeterminable timing in step b).

11. Method (100) according to one of claims 8 to 10, characterized in that a movable search area is specified by a column-wise and / or row-wise non-transparent, transparent, partially transparent or partially non-transparent switching of a plurality of pixels (26).

12. Method (100) according to one of claims 8 to 11, characterized in that steps b), c) and d) are carried out repeatedly for a plurality of predeterminable partial spectra (24), each with a desired intensity (25).

13. Computer program product (60) for controlling an optical filter device (30) with a filter (10) which is designed to determine and output switching signals (43) for actuating a shading means (31) in the beam path of the optical filter device (30), characterized in that the computer program product (60) is designed to carry out a method (100) according to one of claims 8 to 12.

14. A method (200) for simulating an operating behavior of an optical filter arrangement (30), comprising the steps of: a) providing a data set that at least partially simulates a mode of operation of at least one section of the optical filter arrangement (30) to be simulated; b) specifying at least one operating parameter that defines the operating behavior to be simulated; c) executing a simulation program product (70) that is designed to determine at least one performance parameter of the optical filter arrangement (30) based on the data set and the at least one operating parameter; d) outputting the determined performance parameter to a user and / or a data interface (74); characterized in that the optical filter arrangement (30) is designed according to one of claims 1 to 7 and / or for simulating a method (100) according to one of claims 8 to 12.

15. Simulation program product (70) for simulating an operating behavior of an optical filter arrangement (30), characterized in that the simulation program product (70) is designed to carry out a method (200) according to claim 14 and / or is designed to simulate a method (100) according to one of claims 7 to 12.

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