Rotary adjuster for a structure, in particular with an optical element

Abstract

The invention relates to a rotary adjuster (1) for a structure, in particular an optical element (3), preferably a grating and / or mirror with - at least one rotary table with at least one turntable - a drive connected to the rotary table, preferably comprising at least one motor and one gear and / or a motor-gear combination and a rotary mechanism The invention is characterized in that the rotary table comprises an angle measuring system for determining the angular position directly on the turntable, wherein the angle measuring system is preferably an absolute measuring system.

Description

[0001] The invention relates to a rotary adjuster for a structure, in particular an optical structure, in particular with an optical element preferably in the form of a grating and / or a mirror.

[0002] The rotary adjusters according to the invention are particularly preferably used in spectrometers or spectrographs, preferably in spectrometers with one or more grating elements. Other applications in the field of optical instruments, such as a microscope or a device for adjusting a mirror, are also possible.

[0003] When used in an optical setup, such as a microscope or, in particular, a spectrometer, where spectral resolution is preferably provided, precise positioning of the optical elements, such as the spectrometer's mirrors or gratings, is necessary. For the accuracy of the spectral calibration of a spectrometer, for example, it is crucial that the angle of rotation of the optical component, such as the optical grating, relative to the light incident on the component, preferably the grating, is precisely and reproducibly adjusted and maintained.

[0004] In the rotary stages currently in use, the rotary stage itself is driven, for example, via a worm gear and bellows, preferably by means of a stepper motor. The angle of rotation of the rotary stage's turntable is indirectly specified by moving the stepper motor through a known number of microsteps, and the rotation of the turntable is thus indirectly controlled via the rotary stage's reduction mechanism. The microsteps are counted relative to a reference position attached to the rotary stage, which can be determined, for example, via a mechanical limit switch or a light barrier. The resolution of such simple sensors for detecting the reference position is often limited, especially in compact turntables where small angular changes only result in tiny movements of the turntable.For high resolutions in the arcsecond range, either additional information from additional sensors directly on the driving motor axis, thus not yet mechanically reducing the motion, must be used, or extremely high-resolution and thus more complex reference sensors must be used. This further complicates the indirect control of the precise angular position of the turntable that can be achieved this way. Furthermore, after commissioning the system, the reference position must first be approached, thus initializing the system.

[0005] Despite a reduction ratio of 100 to 500:1, and thus 1 to 5 million stepper motor microsteps per rotary table revolution, such state-of-the-art rotary stages (e.g., the DV65-D37 rotary stage from OWIS, the ADT-65 rotary stage from Micos, or the DT-80 rotary stage from Physik Instrumente) exhibit an accuracy of significantly worse than one arcsecond. While it is possible to increase accuracy by increasing the mechanical preload of the components used in the reduction mechanism to minimize their mechanical play, sufficient smoothness must also be ensured to avoid possible step losses of the motor when moving the rotary stage.Gearboxes that are too stiff require large, powerful motors, which in turn introduce a lot of heat and mechanical stress into the system during movement, causing drift and relaxation processes and also preventing a compact design. Therefore, adjusting the preload is difficult and time-consuming. In general, with state-of-the-art rotary stages, by always approaching the target position from the same direction to further minimize the remaining gear play, the residual angular error can be reduced to a sinusoidal error of approximately 20-30 arc seconds. This sinusoidal error is periodic to the motor rotation and is primarily caused by the worm drive. However, to compensate for this residual mechanical error, with state-of-the-art rotary stages, it is necessary to measure this residual error during calibration of the rotary stage and to fit the measured data with a mathematical model.This model is then used to approach the desired target position with greater accuracy.

[0006] A disadvantage of the rotary adjusters and the state-of-the-art method for precise positioning of the rotary adjusters was the relatively high adjustment and assembly effort required for the numerous and diverse components. Since the angular position of the rotary adjuster is only indirectly specified via the microstep position of the stepper motor, mechanical play in particular adversely affects the angular accuracy. Furthermore, despite the complex adjustment and assembly work, the required accuracy was often not achieved, or frequent recalibration was necessary.

[0007] The object of the invention is therefore to provide a rotary adjuster for a structure, in particular for optical elements, preferably a grating and / or a mirror, which avoids the relatively high adjustment and assembly effort in rotary adjusters according to the prior art and makes it possible to directly measure the rotational position of the rotary adjuster, to adjust it with high accuracy and to hold it at a predetermined angular position.

[0008] By directly measuring the angular position of the turntable, it is particularly possible to detect and, if necessary, compensate for subsequent position deviations such as temperature drift or mechanical relaxation.

[0009] A further task is to provide a rotary stage that is compact in design and characterized by small dimensions, low weight and at the same time high precision and positioning accuracy. Rotary stages with dimensions of less than 140mm x 125mm x 60mm in width, length and height for the rotary stage including drive, gear and angle measuring system are therefore preferred. The dimensions of the motor and gear for the proposed rotary stage are LxWxH = 61x61x46 mm. In addition, there is the angle measuring system, i.e. a glass scale and a sensor head. This then results in the dimensions of the entire system with all components being 140x123x57 mm WxLxH. Rotary stages designed in this way and in a compact manner have the advantage that they can be installed in spectrometer setups with compact housings in a space-saving manner and can be easily mounted.At the same time, the compactness and simple installation also allow for easy replacement of the rotary adjuster during service. Furthermore, rotary adjusters with such small dimensions are characterized by their low weight.

[0010] According to the invention, this previously formulated object is achieved by a rotary adjuster having all the features of claim 1.

[0011] The rotary adjuster according to the invention for a structure, in particular an optical element such as a grating and / or a mirror, comprises at least one rotary table with at least one rotary plate and a drive connected to the rotary table, preferably with at least one motor and / or a motor-gearbox combination and a rotary mechanism, as well as an angle measuring system for determining the angular position, wherein the angle measuring system is an absolute measuring system. In the system according to the invention, due to the angle measuring system arranged directly on the rotary plate, the angular position is detected directly on the rotary plate of the rotary adjuster, i.e. after the mechanical reduction, and thus as close as possible to the optical component to be positioned.

[0012] In principle, both incremental and absolute angle measuring systems are possible. According to the invention, the angle measuring system is preferably an absolute measuring system. By using the angle measuring system as an absolute measuring system, it is possible to determine the rotational position of the rotary adjuster directly and absolutely at any time, i.e. without prior reference travel, and to adjust the rotary adjuster from the determined rotational position until the desired angle of rotation is reached. This offers advantages, in particular when switching on the system, since the grating or mirror does not have to be moved time-consumingly to a known reference position, from which the position can then be determined incrementally. At the same time, with an absolute measuring system, no incremental pulses can be lost due to interference, which makes the measurement considerably more robust and therefore more accurate.

[0013] To adjust the angle of rotation, a control and / or regulating system or a control and / or regulating device is provided which, after determining the rotational position, controls the rotary adjuster in such a way that the rotary adjuster, which is preferably motor-driven, adjusts in such a way that the desired rotational position, i.e. the desired angle of rotation, is reached or maintained.

[0014] In particular, the angle of rotation is adjusted with the aid of the control and / or regulating device in such a way that a mechanical inaccuracy of the rotating mechanism is compensated for, for example, by drift movements, mechanical stress relief, or relaxation processes.

[0015] It is particularly preferred if the angle of rotation is adjusted, in particular with the aid of the control and / or regulating device, such that an angular accuracy of better than one arcsecond, preferably better than half a arcsecond, is achieved. This is particularly advantageous because such accuracies are already achieved through tracking and, in contrast to the prior art, no complex adjustment or the use of nonlinear fitting routines is required. Active tracking also reduces or, preferably, completely eliminates the need for frequent and complex recalibrations to ensure long-term accuracy.

[0016] In another operating mode of the rotary stage, it is also possible to forego automated active tracking in the case of deviations below a specified threshold value and instead to allow small position deviations below the threshold value, but to measure the position deviations over time and to make them available to a downstream unit for later software correction of the measured spectra.

[0017] This operating mode is particularly advantageous when the rotary stage is to remain completely stationary during spectra recording or when the measurement accuracy of the angle measurement is significantly better than the achievable positioning accuracy of the rotary stage, which is limited by the mechanically reduced minimum motor movement of the rotary stage.

[0018] The adjustment of the rotary stage is preferably achieved using a stepper motor. It is particularly preferred if the gearbox, particularly the gearbox of the motor-gearbox combination, comprises a harmonic drive to achieve a low synchronization error and a compact design. A harmonic drive, or a so-called "harmonic drive," is characterized by a high reduction ratio and zero backlash, thus ensuring high positioning and repeatability accuracy.

[0019] Wave gears have three components: 1. an elliptical steel disc (so-called “wave generator”) in the center of the gearbox, whereby the gearbox has a central hub as well as a thin, elliptically deformable special ball bearing, 2. a flexspline, which is a deformable, cylindrical steel bushing with teeth arranged radially around the outside and 3. a circular spline, which is a rigid and cylindrical outer ring surrounding both the wave generator and the flexspline and is equipped with internal teeth.

[0020] The external toothing of the flexspline has fewer teeth than the internal toothing of the circular spline. This difference is often two teeth. Typically, the wave generator is used as the input element, which is coupled to the motor, and the flexspline as the output element of the mechanism. The elliptical wave generator, as the driven element, initiates the process of the wave gear and initially deforms the flexspline. The flexspline is located in mesh with the internally toothed circular spline in the opposite areas of the major axis of the ellipse. The rotation of the wave generator shifts the major axis of the ellipse and thus also the tooth meshing area. A crucial factor for the design and functioning of the wave gear is that the flexspline has fewer teeth than the circular spline.With a difference of, for example, two teeth, a relative movement of one tooth occurs between the flexspline and the circular spline after half a rotation of the wave generator. After a full rotation, the difference is already two teeth. This results in a strong reduction ratio with simultaneous high backlash and high torsional rigidity.

[0021] In order to determine the exact location of the rotary table and thus of the optical element mounted on the rotary table, in particular the grating and / or the mirror, the angular positioning system of the invention has an angle measuring system or, in particular, a partial circle angle measuring system. This can be a magnetic, inductive, or preferably optical angle or partial circle angle measuring system. The optical partial circle angle measuring system is preferably in the form of a measuring tape, for example made of steel, with periodically applied measuring markings, which is applied to a circumference, in particular of the rotary table that supports the optical element, preferably the grating and / or the mirror. The angle measuring system or partial circle angle measuring system is preferably in the form of a linear length measuring tape, for example, glued and / or pressed onto the edge of the rotary table.The position of the rotary table is determined via the measuring tape on the circumference with the aid of at least one sensor. The sensor is preferably an absolute sensor with which the markings applied to the linear measuring tape are detected and the position is thus determined. In one embodiment of the invention, the absolute sensor is an optical sensor. The optical sensor preferably comprises a photoelectric sensor with which the markings on the measuring tape are detected or, in particular, an extremely fast digital camera or digital line scan camera that continuously takes pictures of the measuring tape and the markings on it. The measuring tape bears unique markings so that, similar to looking at a meter stick or a macroscopic measuring tape, the position of the section of the measuring tape read at the time of measurement is detected by the sensor head.The markings on the scale are preferably stored in digital form and most preferably as contrast stripes in the form of barcodes with a nominal pitch of 20-30 µm. Special coding, such as 8B / 10B, 64B / 66B, or 64B / 67 coding, ensures that a sufficient number of contrast stripes, and thus signal changes, are present in the sensor's viewing window at all times. This ensures that the sensor, which detects not only individual lines but always a range of 20-100 contrast stripes simultaneously, can always determine a valid position. The exact functionality of such absolute sensors is described by the manufacturers of such sensors, for example, Renishaw (https: / / www.renishaw.de / de / funktionsweise-der-optischen-messsysteme-vonrenishaw--36979) and is intended to be incorporated in its entirety into this application.

[0022] The absolute sensor determines the absolute linear position on the scale with a resolution of less than 100 nm, and preferably less than 50 nm. An evaluation unit then calculates the angular position of the rotary stage from the determined absolute position and the diameter of the measuring scale. For example, if the diameter of the turntable is 100 mm and the scale is mounted on the circumference of the turntable, an angular resolution of less than 0.5 arcseconds is achieved, significantly better than one arcsecond.

[0023] A particularly high positioning accuracy and compactness is achieved if, as described above, the gear is designed as a wave gear, wherein the wave gear preferably comprises a flexspline and a circular spline and has a high reduction ratio of at least 80:1 and preferably at least 100:1.

[0024] In addition to the rotary adjuster, which is characterized according to the invention by a particularly high accuracy, the invention also provides a device for Raman, in particular confocal Raman and / or fluorescence microscopy and / or spectroscopy, wherein the device comprises a rotary adjuster according to one of the previously described embodiments and an optical element arranged on the rotary adjuster, in particular a mirror and / or a grating.

[0025] With the help of the rotary stage according to the invention, extremely precise angular positioning can be achieved, especially in a spectrometer. The rotary stage according to the invention achieves reproducibility in the range of significantly less than one arcsecond.

[0026] The following describes the advantages of using a rotary stage according to the invention in a spectrometer. For example, in a spectrometer with a focal length of 600 mm, the CCD camera used to record the spectra is also 600 mm away from the optical grating. Typically, in spectrometry, gratings are used in reflection mode. An error in the angular positioning of the grating or mirror therefore has a double effect: on the angle of the incident light and the angle of the reflected light. In the exemplary embodiment cited, an error of one arcsecond in the angular positioning of the grating at a distance of 600 mm on the CCD camera thus represents a shift of approximately 5.6 µm. The CCD cameras used in such spectrometers typically have pixel sizes in the range of 15–26 µm.To ensure that the error caused by angular positioning remains smaller than one CCD pixel, the angular positioning must be better than 3-5 arcseconds. Smaller CCD pixels are technically possible, but they collect too little light per unit time and become too insensitive to light. However, the spectral resolution of spectrometers is usually not limited by the CCD pixel size. Typical spectral lines in a spectrometer are usually mapped onto multiple CCD pixels. By fitting spectral lines, for example using a Gaussian or Lorentz function, and determining the spectral center of gravity, interpolation in the CCD sub-pixel range is possible. By fitting spectral lines, spectral resolutions of the spectrometer from fractions down to 0.01 CCD pixels and less are possible. Angular positioning errors of the grating in the range of arcseconds are therefore clearly visible and can significantly distort spectral measurements.Angular positioning errors in the sub-arcsecond range are very advantageous because they ensure that the resolution improvement achieved through the fitting process is no longer overlaid by errors and thus becomes usable. Fitting the spectral lines is necessary because otherwise the pixel size of the CCD camera limits the spectral resolution. At the same time, the CCD pixels must not be too small, as otherwise they would become too insensitive to light or collect too little light in a given time.

[0027] In addition to the rotary adjuster for different optical elements, the invention also claims an optical device, in particular a spectrometer with such a rotary adjuster, as well as a method for adjusting a rotation angle of a rotary adjuster with a rotation table and an angle measuring system or pitch circle measuring system arranged thereon.

[0028] The invention will now be described by way of example and without limitation with reference to the accompanying drawings.

[0029] They show: Fig. 1: a rotary adjuster according to the invention for an optical element, in particular a grating for use in a spectrometer Fig. 2: Rotary adjuster according to the invention with applied pitch circle measuring tape, sensor, drive and evaluation devices Fig. 3: Schematic structure of the assembly of a rotary adjuster according to the invention consisting of rotary adjuster, pitch circle measuring tape, sensor and motor with directly mounted wave gear Fig. 4: schematic structure of a wave gear Fig. 5: Detail of the markings (barcode consisting of contrasting stripes; the absolute position is stored in the barcode as a coarse position in coded form; the fine position is determined by interpolation of the lines) on a measuring tape according to the invention Fig. 6: Schematic structure of the detector for reading the pitch circle measuring tape Fig. 7: Dimensions of the fully assembled rotary adjuster according to the invention with length L, width B and height H Fig. 8: Achieved calibration result of a 600mm spectrometer equipped with a rotary stage according to the invention: The graph shows the residual error after calibration in pixels (16µm) versus the different positions of the CCD chip.

[0030] In Fig. Figure 1 shows the schematic structure of a spectrometer, for example a Raman spectrometer as known from WO 2018 / 158 136 A1 or WO 2011 / 131311 A1, with a rotary adjuster 1 according to the invention and an optical element 3, for example a grating or mirror arranged on the rotary adjuster. The disclosure content of WO 2018 / 158 136 A1 and WO 2011 / 131311 A1 is incorporated in its entirety into the present application. In a spectrometer, in particular a Raman spectrometer, an optical grating is illuminated through an entrance slit 2 or pinhole by a light beam 5 from a light source. The pinhole can also preferably be formed by the end of a glass fiber. The coupled-in light is preferably Raman scattered light, i.e. essentially a light source that, in addition to the excitation wavelength, also contains non-monochromatic light components.The light beam 5 strikes the optical element, e.g., a grating, arranged on a rotary stage 1 and is deflected in direction 7, e.g., onto a camera 9. This can occur through diffraction in the case of a grating, or through reflection in the case of a mirror. The distance between camera 9 and the optical element, e.g., grating 3, on the rotary stage is preferably approximately 300 mm to 600 mm. The grating arranged on the rotary stage is preferably a grating spectral filter of a spectrometer. In a Raman spectrometer, the beam of Raman light is expanded by suitable optics. The expanded beam then strikes the grating spectral filter mounted on the rotary stage. The grating spectral filter diffracts the light in different directions depending on its wavelength, so that, for example, a location-dependent spectral signal can be recorded on a CCD chip.The CCD chip, for example, has 1024 channels, whereby the 1024 channels of the CCD chip can capture light of different wavelengths. The rotary stage is designed to achieve a minimum error of better than 1 arcsecond, preferably better than half an arcsecond. For this purpose, the angle of rotation of the rotary stage is measured, evaluated using a control and regulating device, and the angular position is adjusted using the control and / or regulating device in such a way that any mechanical inaccuracy of the rotary mechanism is compensated for and an angular accuracy of better than 1 arcsecond, preferably better than half an arcsecond, is achieved.

[0031] In Fig. Figure 2 shows the entire system of a rotary adjuster according to the invention. An optical element, e.g., a grating or grating spectral filter, is arranged on the rotary plate 4 of the rotary adjuster. A graduated circle measuring standard in the form of a measuring tape 11 with an imprint (not shown) is applied, e.g., by gluing, to the edge of the rotary table of the rotary adjuster. The graduated circle measuring standard contains coded length or angle information, which is evaluated by the sensor 10 and serves to sense the rotary position of the rotary adjuster. Depending on the detected rotary position of the rotary adjuster, the motor then adjusts the rotary adjuster until the desired angle of rotation is reached. A grating or grating spectral filter 3 is arranged on the rotary table of the rotary adjuster.

[0032] To sense the rotational position reached by the rotary adjuster, a sensor 10 records the absolute position of the rotary adjuster via the measuring scale on the tape measure. The position of the rotary adjuster is transmitted to a control / regulating device 14, preferably in the form of a digital microcontroller. From the rotational position of the rotary adjuster, which was determined using the absolute angle measuring system, the turntable 4 of the rotary adjuster 1 can be adjusted such that the desired angle of rotation is reached and maintained. The pitch circle angle measuring system is applied to the turntable, e.g., by gluing, whereby a precise angular position can be determined using the angle measuring system. The control / regulating system 14 allows the angle of rotation to be adjusted via the motor 13 and the gear 12 of the rotary adjuster such that any mechanical inaccuracies in the rotary mechanism are compensated for.The angles determined with the angle measuring system according to the invention have an angular accuracy of approximately 1 to 0.5 arcseconds. This accuracy can be achieved without complex adjustment or fitting routines. The angle measuring system according to the invention is an absolute measuring system, which eliminates the previously necessary light barriers for reference positions and time-consuming reference runs to these reference positions for initialization after system commissioning, as is necessary with incremental sensors. This results in a significant simplification in the design and operation of the system. Another advantage is the increased robustness of such an absolute system, since individual incorrect measurements, for example caused by contamination or vibrations, cannot influence subsequent measurements and thus falsify them (for example, by integrating previous measurement errors).

[0033] In Fig. Figure 3 shows the schematic assembly of the components of a rotary adjuster according to the invention. The rotary adjuster's rotary plate 4 is mounted directly on the gear flange 111 of the shaft gear 12, with the gear also being mounted directly on the motor flange, so that the motor and gear form a compact motor-gear combination, and the motor axis and gear axis are directly connected to each other. The measuring scale 11 of the angle pitch circle measuring system is applied to the circumference of the rotary plate 4 by gluing or pressing and is evaluated via the sensor 10.

[0034] Fig. 4 shows a top view of the essential parts of a harmonic drive as used in the drive of the rotary adjuster 1. The harmonic drive, also known as a "harmonic drive", according to Fig. 4 comprises an elliptical disk 100 in the center of the gear, which has a central hub and a thin, elliptically deformable special ball bearing. Furthermore, the harmonic drive consists of a flexspline 110 with a toothing 112 arranged radially around the outside and a circular spline 120 with an internal toothing 122. A significant feature of the "harmonic drive" is the number of teeth, with the external toothing of the flexspline 110 having fewer teeth than the internal toothing 122 of the circular spline 120. This results in the gear reduction. The elliptical "wave generator" 100, as the driven element, initiates the process of the harmonic drive and deforms the initiating flexspline 110. The flexspline engages the internally toothed circular spline 120 in the opposite areas of the major ellipse axis.The rotation of the wave generator shifts the major axis of the ellipse and thus the tooth engagement area. The key factor is that the flexspline always has fewer teeth than the circular spline. With a fixed circular spline, the flexspline, as the output element, rotates in the opposite direction to the input.

[0035] A key advantage of the strain wave gear over conventional gears is the high achievable reduction ratio and absolute backlash-free performance throughout its service life, as well as high torsional rigidity across the entire torque range. Furthermore, this gear type is characterized by its small size and low weight compared to conventional gear types. Furthermore, the high reduction ratio and backlash-free performance ensure high positioning and repeatability accuracy.

[0036] The compact design of the gearbox also allows for direct mounting on the flange of the stepper motor, allowing the motor axis and gearbox axis to be directly connected. This results in very compact motor-gearbox combinations that are easily interchangeable if necessary and do not require additional axle couplings, such as the bellows often required to compensate for axle misalignment. This further simplifies the overall design and avoids mechanical backlash in the entire system, caused, for example, by possible torsion of long drive axles.

[0037] Fig. Figure 5 shows the markings, in particular the contrast stripes, which form a barcode and contain the position or angle information in a coded manner.

[0038] The single-track scale features full-width contrast stripes based on a nominal pitch of 30 µm. The absence of multiple parallel tracks provides the system with important immunity to yaw angle errors in sensor head alignment and a larger lateral tolerance.

[0039] The barcodes are preferably generated by feedback shift registers, since these methods for generating the barcode are self-synchronizing and also ensure that signal changes in the bit sequences occur sufficiently often, thus ensuring that the barcodes have a sufficient density.

[0040] In Fig. Figure 6 schematically shows the beam path of the optical pitch circle measuring system. To read the measuring standard 11, a light source 202, for example, an LED, briefly illuminates an area of ​​the measuring standard 11 opposite the sensor 200 at the time of reading via the illumination beam path 204. A prism or mirror 205 serves to direct the beam path and ensures that the illumination and detection beam paths 203 illuminate and detect the same area on the measuring standard. This allows a fast digital camera 201 to capture an image of the illuminated section of the measuring standard via the detection beam path 203 through the exit window 206 of the sensor, which image encompasses a range of 40-100 contrast stripes of the barcode.

[0041] Each contrast stripe is mapped onto several neighboring camera pixels, allowing the position of each contrast stripe to be determined with sub-pixel resolution through interpolation. This image is digitized and evaluated using digital signal processing.

[0042] A first algorithm then determines the number stored in the barcode in coded form, thus determining the absolute coarse position. Meanwhile, another routine calculates a high-resolution fine position by interpolating the exact positions of the individual bars in the camera image, which is then combined with the coarse position to provide a very high-resolution absolute position.

[0043] Fig. Figure 7 shows the compactness of a fully assembled rotary actuator according to the invention. All components are located within a cube with length L, width B, and height H.

[0044] Fig. Figure 8 shows the residual error after calibration of a spectrometer equipped with a rotary stage according to the invention. To demonstrate the great potential of the rotary stage, a spectrometer with a long focal length (600 mm) was used, and a grating with very high dispersive power (2400 g / mm) was installed in the spectrometer. The long focal length ensures that the positioning error of the rotary stage is amplified (here 12-fold). For gratings with high dispersive power, a large angular range of the rotary stage (here 38°) must be used simultaneously to image the desired spectral range onto the CCD chip (here 1650 pixels of 16 µm).

[0045] Spectrometer calibration typically uses light sources with a known emission spectrum. The emission lines of gas discharge lamps are particularly suitable for this purpose because they have a very narrow spectral width and their wavelength is known to within 0.0001 nm. For this calibration, the lines (404.6565 nm (301); 435.8335 nm (302); 546.0750 nm (303); 576.9610 nm (304); 696.5431 nm (305); 738.3980 nm (306)) of a mercury-argon gas discharge lamp were used.

[0046] When acquiring the calibration data, each spectral line is positioned at different positions (here 15 positions) of the CCD chip using the rotary stage and its exact position on the chip is measured.

[0047] The data obtained (angle of the rotary stage, wavelength of the emission line and position on the chip) can be fitted to a mathematical model that includes the optical and geometric properties of the spectrometer. The deviation from this mathematical model is the residual error, which is Fig. 9 was plotted against the chip position.

[0048] Since the position determination of the spectral lines here only has an accuracy of approximately 1 / 10 pixel, the actual positioning error of the rotary adjuster is likely to be even smaller.

[0049] The invention provides, for the first time, a rotary stage, particularly for use in spectrometers or microscopes, that does not require an initial reference run and is characterized by high accuracy and small dimensions and weight. It is characterized by the fact that it can be used to set and maintain very precise angular positions of an optical component, such as a grating. Furthermore, it no longer requires a home position, for example, with multiple light barriers.

[0050] The invention includes aspects which are the subject of the following sentences but are not claims according to J 15 / 88: Sentences 1. Rotary adjuster (1) for a structure, in particular an optical element (3), preferably a grating and / or mirror with - at least one rotary table with at least one turntable - a drive connected to the rotary table, preferably comprising at least one motor and one gear and / or a motor-gear combination and a rotary mechanism, characterized in that the rotary table comprises an angle measuring system for determining the angular position directly on the turntable, wherein the angle measuring system is preferably an absolute measuring system. 2. Rotary adjuster (1) according to sentence 1, characterized in that a control and / or regulating device is provided. 3. Rotary adjuster (1) according to one of the sentences 1 to 2, characterized in that from the determined angular position, the angle of rotation is adjusted with the aid of the control and / or regulating device (14) in such a way that a mechanical inaccuracy of the rotation mechanism caused, for example, by drift movements, mechanical stress build-up or relaxation processes is compensated. 4. Rotary adjuster (1) according to one of the sentences 1 to 3, characterized in that with the aid of the control and / or regulating device the angle of rotation is adjusted in such a way that an angular accuracy of better than 1 arc second, preferably better than half a arc second, is achieved. 5. Rotary adjuster (1) according to one of the sentences 1 to 4, characterized in that the drive motor is a stepper motor. 6. Rotary adjuster (1) according to one of the sentences 1 to 5, characterized in that the angle measuring system comprises a pitch circle angle measuring system. 7. Rotary adjuster (1) according to sentence 6, characterized in that the pitch circle angle measuring system comprises a measuring tape (20), preferably a measuring tape made of steel with periodically applied measuring markings, which is preferably applied, preferably glued and / or pressed onto an edge, in particular of the rotary table. 8. Rotary adjuster (1) according to one of the sentences 1 to 7, characterized in that the angle measuring system comprises at least one sensor, preferably an absolute sensor, in particular an optical sensor, preferably a digital camera or digital line scan camera. 9. Rotary adjuster (1) according to one of the sentences 1 to 8, characterized in that the transmission, in particular the motor-transmission combination, has a reduction ratio of at least 80:1 and preferably at least 100:1. 10. Rotary adjuster (1) according to one of the sentences 1 to 9, characterized in that the gearbox is mounted directly on the motor flange. 11. Rotary adjuster (1) according to one of the sentences 1 to 10, characterized in that the gearbox and the motor axis are mounted directly and parallel to the axis. 12. Rotary adjuster (1) according to one of the sentences 1 to 11, characterized in that the rotary plate of the rotary adjuster is mounted directly on the gearbox. 13. Rotary adjuster (1) according to one of the sentences 1 to 12, characterized in that the transmission, in particular the motor-transmission combination, is a wave transmission. 14. Rotary adjuster (1) according to sentence 13, characterized in that the wave gear comprises a flexspline (110) with teeth arranged radially around the outside and a circular spline (120) with internal teeth. 15. Rotary adjuster (1) according to sentence 13, characterized in that the external toothing of the Flexspline (110) has fewer teeth than the internal toothing of the Circular Spline (120). 16. Device for Raman, in particular confocal Raman and / or fluorescence microscopy and / or spectroscopy with at least one optical element, in particular a grating and / or mirror and at least one rotary adjuster (1), characterized in that the optical element is arranged on the rotary adjuster (1). 17. Device according to sentence 13, characterized in that the rotary adjuster (1) is a rotary adjuster according to one of sentences 1 to 12. 18. Device according to one of sentences 15 to 17, characterized in that the device comprises a housing which accommodates the rotary adjuster with the optical element. 19. Device according to one of sentences 15 to 17, characterized in that the rotary adjuster comprises a rotary table and the dimensions of the rotary adjuster by a length, a width and a height are marked. 20. Device according to sentence 19, characterized in that the length L and the width B of the rotary adjuster are less than L < 125 mm and B < 140 mm. 21. Device according to one of sentences 19 to 20, characterized in that the height is less than 60 mm 22. A method for adjusting a rotation angle of a rotary adjuster having a rotary table and at least one measuring element or pitch circle measuring element attached thereto, which has coded length or angle information, comprising the following steps: - by means of a sensor (10) the absolute rotational position of the rotary adjuster is determined on the basis of the coded length or angle information, - the absolute position is transmitted to a control device - Due to the absolute rotational position, the rotary adjuster is preferably adjusted by means of the control device via the motor and gear until the desired angle of rotation is reached and mechanical inaccuracies of the rotary mechanism are compensated. 23. Procedure according to sentence 22, characterized in that the angle of rotation is set with an angular accuracy better than 5 arcseconds, preferably better than 1 arcsecond, particularly preferably better than 0.5 arcseconds. List of reference symbols: 1 rotary adjuster 2 Entrance slit or pinhole 3 Optical element (optical grating or mirror) 4 turntables 5.7 light beam 9 Camera 10 sensors 11 Measurement embodiment 12 gearboxes 13 Engine 14 Control and regulation device 15 Coded position information 100 Elliptical disc (motor driven) 110 Flexspline (gearbox output) 111 Gearbox flange (connected with Flexspline) 112 External teeth Flexspline 120 Circular Spline (gearbox housing) 121 Gear housing (connected with circular spline) 122 Internal gearing Circular Spline 130 Centric hub 200 sensors 201 Camera 202 Lighting source 203 Detection beam path 204 Illumination beam path 205 prism or mirror 206 exit windows 301 Measured deviation of peak position at 404.6565nm 302 Measured deviation of peak position at 435.8335nm 303 Measured deviation of peak position at 546.0750nm 304 Measured deviation of peak position at 576.9610nm 305 Measured deviation of peak position at 696.5431 nm 306 Measured deviation of peak position at 738.3980nm QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 158 136 A1

[0030] WO 20117131 311 A1

[0030] WO 2011 / 131311 A1

[0030] Cited non-patent literature

[0000] https: / / www.renishaw.de / de / how-renishaw-optical-measurement-systems-work--36979

[0021]

Claims

[1] Rotary adjuster (1) for a structure, in particular an optical element (3), preferably a grating and / or mirror with - at least one rotary table with at least one turntable - a drive connected to the rotary table, preferably comprising at least one motor and one gear and / or a motor-gear combination and a rotary mechanism characterized by that the rotary table comprises an angle measuring system for determining the angular position directly on the turntable, wherein the angle measuring system is preferably an absolute measuring system. [2] Rotary adjuster (1) according to claim 1, characterized by that a control and / or regulating device is provided. [3] Rotary adjuster (1) according to one of claims 1 to 2, characterized bythat the angle of rotation is adjusted from the determined angular position with the aid of the control and / or regulating device (14) in such a way that a mechanical inaccuracy of the rotation mechanism caused, for example, by drift movements, mechanical stress build-up or relaxation processes is compensated. [4] Rotary adjuster (1) according to one of claims 1 to 3, characterized by that with the aid of the control and / or regulating device the angle of rotation is adjusted in such a way that an angular accuracy of better than 1 arc second, preferably better than half a arc second, is achieved. [5] Rotary adjuster (1) according to one of claims 1 to 4, characterized by that the drive comprises a stepper motor as the motor. [6] Rotary adjuster (1) according to one of claims 1 to 5, characterized by that the angle measuring system comprises a pitch circle angle measuring system. [7] Rotary adjuster (1) according to claim 6, characterized bythat the pitch circle angle measuring system comprises a measuring tape (20), preferably a measuring tape made of steel with periodically applied measuring markings, which is preferably applied, preferably glued and / or pressed onto an edge, in particular of the rotary table. [8] Rotary adjuster (1) according to one of claims 1 to 7, characterized by that the angle measuring system comprises at least one sensor, preferably an absolute sensor, in particular an optical sensor, preferably a digital or digital line scan camera. [9] Rotary adjuster (1) according to one of claims 1 to 8, characterized by that the gearbox, especially the motor-gearbox combination, is a wave gear. [10] Rotary adjuster (1) according to claim 9, characterized by that the wave gear comprises a flexspline (110) with teeth arranged radially around the outside and a circular spline (120) with internal teeth. [11] Rotary adjuster (1) according to claim 10, characterized bythat the external toothing of the Flexspline (110) has fewer teeth than the internal toothing of the Circular Spline (120). [12] Device for Raman, in particular confocal Raman and / or fluorescence microscopy and / or spectroscopy with at least one optical element, in particular a grating and / or mirror and a rotary adjuster (1), characterized by that the optical element is arranged on a rotary adjuster (1) according to one of claims 1 to 11.

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