Device for conducting measurement light to be spectroscopic, method for producing such device, and device for distance and

Abstract

The invention relates to a device for conducting measurement light to be spectroscopically analyzed in a distance and / or thickness measuring system, in particular in a confocal chromatic or interferometric distance and / or thickness measuring system, comprising an optical waveguide (11), the optical waveguide (11) having an exit end (12) for the measurement light, which exit end is preferably held by a ferrule, the invention is characterized in that a diaphragm (1) having a diaphragm opening (4) is arranged on the exit end (12). Furthermore, a method for producing such a device and a device for distance and / or thickness measurement are described.

Description

Technical Field

[0001] A device for conducting measuring light to be spectrally analyzed in a distance and / or thickness measuring system, in particular a confocal chromatic or interferometric distance and / or thickness measuring system, has an optical waveguide with an output end for the measuring light, which is preferably held by a ferrule.

[0002] The invention further relates to a device for distance and / or thickness measurement, in particular for interferometric and / or confocal chromatic distance and / or thickness measurement.

[0003] The invention also relates to a method for producing a device according to the invention. Background Art

[0004] Confocal chromatic and interferometric distance and thickness measuring systems are known from the prior art, in which the measuring light to be spectrally analyzed is fed into the spectrometer using a multimode optical waveguide. The end of the usually circular optical fiber also has the function of a (point) aperture for the light dispersively output from the fiber. The spectral image of the fiber end, modified by the dispersive optical element, is ultimately imaged on a line detector or multi-line detectors. The active area (pixel) of the detector is usually square, but in the case of particularly sensitive line detectors it can also be rectangular, wherein in this case the height of the individual active cells is greater than the distance between the pixels, also called the pixel pitch.

[0005] Such measuring systems are constantly in need of increasing measuring speed and distance resolution, as well as simultaneously resolving the distance between two or more layers to a high degree for layer thickness measurement. Therefore, in addition to using more sensitive detectors that can be read faster, it is also important to provide as much measuring light as possible with a good signal-to-noise ratio in order to increase speed.

[0006] In order to improve the absolute distance resolution of individual measurement objects or targets or layers within a determined measurement range, it is sufficient for a confocal chromatic aberration measurement system to scan the spectrum to be analyzed using a sensor with a higher pixel density. This makes more measurement points available for analog-to-digital conversion, which ultimately allow for more stable signal analysis and center of gravity determination. When only one distance is measured, the pixel-related peak width in the spectrum diagram initially has no meaning. However, if the distance between two closely spaced reflections in the spectrum diagram is to be resolved accurately enough when measuring material thickness, the pixel-related width of the individual measurement peaks must be reduced in order to delay the signal superposition as much as possible when the distance is shortened due to steep signal edges. The reason for this is the accumulation of individual peaks during superposition, which ultimately leads to the merging of the individual signals and, as a result, their analytical inability to be separated.

[0007] Using interferometric measurement methods, narrower peaks lead to higher modulation of high frequencies, so the distance resolution is significantly improved.

[0008] In order to achieve an improved resolution of the distance between two close reflections, it is necessary, according to this realization, to reduce the fiber image on the spectrometer line. This can be achieved by using smaller fibers. However, this improvement in spectral clarity is accompanied by a significant loss in the intensity of the measured light, since the other fiber end on the light source side captures less light. This ultimately leads to longer exposure times and, therefore, lower measurement frequencies.

[0009] Another possibility to reduce the beam diameter on the row without significant light losses is to reduce the imaging of the fiber ends on the detector row by designing the optics that are required anyway accordingly. However, this approach is disadvantageous because it has significant disadvantages due to the higher requirements for correcting the imaging errors of the optics, in particular for the larger field angles of the necessarily more dispersive spectral decomposition elements. This includes the increased space requirement and increased weight due to the more complex optics, as well as the significantly higher costs for producing these optics.

[0010] A solution that initially seemed promising was to taper the fiber end that ends in the spectrometer by a fiber pulling process under the influence of heat. However, if you look more closely, only a smaller solid angle is transmitted from the light source side to the detector surface while the light source remains unchanged. This results in a smaller light spot, but at the same time its overall intensity is reduced, since only a smaller area of ​​the light source is captured. Ultimately, the reduction in peak width is also accompanied by a disadvantageous loss of intensity here.

[0011] In addition, reference is made only by way of example to document WO 2021 / 255584 A1. There is described an optical measuring device for measuring the distance and / or thickness of a measurement object. The optical measuring device comprises a measuring head and an evaluation unit, the measuring head having an imaging optical device, wherein the measuring head is connected to the evaluation unit via two light-guiding optical fibers. The evaluation unit comprises a light source, the light of which is guided into the measuring head via a first light-guiding optical fiber. The light reflected from the measurement object is guided back through the measurement head and enters the second light-guiding optical fiber with the aid of a beam splitter, thereby separating the incident light and the reflected light, wherein the ends of the optical fibers are in mutually conjugated positions. In addition, separate aperture mechanisms are respectively constructed in front of the ends of the optical fibers facing the measurement object. These aperture mechanisms must be positioned extremely precisely in all three spatial directions and then fixed. Therefore, the adjustment is extremely complicated, and the mechanical and thermal stability are low due to the need to connect the individual components. Summary of the invention

[0012] The object of the present invention is therefore to design and improve a device for conducting measuring light to be analyzed spectrally in such a way that as much measuring light as possible with a good signal-to-noise ratio is provided using components of simple construction. In addition, a method for producing such a device is to be proposed. In addition, an improved device for distance and / or thickness measurement is to be proposed.

[0013] According to the invention, this object is achieved by the features of claim 1. According to this, the device in question is used for guiding measurement light to be spectrally analyzed in a distance and / or thickness measuring system, in particular a confocal chromatic or interferometric distance and / or thickness measuring system, and has a light waveguide, wherein the light waveguide has an exit end for the measurement light, which is preferably held by a ferrule, and is characterized in that an aperture with an aperture opening is arranged at the exit end.

[0014] For the device, this object is achieved by the features of the independent parallel claim 13. A device for distance and / or thickness measurement, in particular for interferometric and / or confocal chromatic distance and / or thickness measurement, is claimed, which has a device for conducting measuring light according to any of claims 1 to 12 and a spectrometer with a detector for evaluating the measuring light, wherein the output end of the optical waveguide is arranged in and / or on the spectrometer, the output end having an aperture with an aperture opening.

[0015] The device according to the invention achieves a significant increase in the optical power, since the diameter of the optical waveguide, in particular the diameter of the optical fiber, is significantly increased while maintaining the same spectral separation accuracy, so that a significantly larger amount of light can be processed in the measuring system. This is ultimately reflected in a significant increase in the possible measurement frequency, even on materials with low reflectivity. This is particularly important when used in devices with rectangular detector row geometries with a pixel aspect ratio (PAR) far below 1, so that the device according to the invention can advantageously have such a detector. Another advantage is that a higher separation accuracy can be achieved compared to systems using unshielded optical waveguides. The separation accuracy of a detector, in particular a spectrometer, refers to the ability to clearly distinguish two closely spaced maxima of a continuous spectrum by scanning discretely in space. In the manner according to the invention, a significantly higher separation accuracy can be achieved in a spectrometer, since the width of the light source image can be adapted to the aspect ratio of the row by shielding, in particular at the sides. For distance measuring systems, an increase in the separation accuracy in an otherwise identical system ultimately means an increase in the distance resolution. The aperture can be attached directly to the exit end or arranged thereon in any other way. Another advantage is the variable light power, because in addition to changing the light intensity, by adjusting the size of the aperture opening, it is also possible to respond to the different light powers required for a particular measurement task. Here, it is sufficient to simply use optical waveguides with different aperture geometries.

[0016] Furthermore, the teaching according to the invention is characterized by a particularly easy positioning of the aperture opening. The positioning of the aperture opening relative to the optical waveguide, in particular relative to the optical fiber core, can be achieved by an easily automated method with very high reproducibility, in particular if the exit end of the optical waveguide or optical fiber is embedded in a ferrule, which preferably has a center position tolerance of <1 μm. Furthermore, it is conceivable and advantageous that the exit end of the optical waveguide or optical fiber has a circular cross section. Another advantage is that by arranging the aperture at the exit end of the optical waveguide, the optical waveguide is suitable for being arranged in a spectrometer instead of in a measuring head. This configuration is achieved by the device according to the invention. Compared with arranging the aperture on the measuring head side, this has the further advantage that the aperture has no influence on the projection of the measuring light onto the measured object, but only on the projection of the light (in particular spectrally resolved light) onto the detector or detector row. Therefore, only the spectral resolution is increased by the aperture.

[0017] The aperture opening is advantageously designed as a slot. In other words, the effective opening has an elongated, narrow geometry. The elongated sides of the aperture opening can extend at least substantially parallel to one another in a further advantageous manner. This allows the image of the optical waveguide to be adapted to the geometry of the pixels of the downstream detector. In a further advantageous manner, the detector of the device according to the invention can be designed as a line detector or a multi-line detector. Such a detector can have square or rectangular pixels, in particular with a pixel aspect ratio PAR=xp / yp=pixel width / pixel height in the range of 1 / 40 to 1 / 20. The slot-shaped aperture opening allows better utilization of the effective area of ​​the line detector or multi-line detector.

[0018] In a further advantageous manner, the aperture opening can have a shape other than a rectangle, in particular can be designed as a pillow, barrel, lens or ellipse. By design, the aperture opening can be adapted to the detector in an ideal manner, so that an improved signal-to-noise ratio can be achieved. Alternatively or additionally, a perforated opening can be constructed on the aperture. Such perforations can be implemented in particular as microperforations and generally have the advantage that the edge sharpness of the aperture image on the detector can be changed and the shape of the peak can thus be adapted to the requirements of the measuring system. This effect can also be achieved by making the aperture partially transparent at least in the edge region of the aperture opening.

[0019] According to an advantageous design, the aperture opening can have a chamfered edge at least in certain areas. Furthermore, if the material of the aperture is not completely optically impermeable or partially transparent, a softer edge profile can be achieved in this way when the aperture is imaged on the detector. This achieves an advantageous effect similar to that of an aperture formed from a partially transparent material.

[0020] In an advantageous manner, the aperture can be formed by a coating which is applied to the exit end and is partially transparent or opaque to the measuring light, for example by lacquer. Effective shielding is thereby achieved in a particularly simple manner. The coating can be partially removed by microablation, laser ablation or mechanically in order to thereby form the aperture opening. It is also conceivable that the partially transparent or opaque coating is printed on the exit end. Thus, the shape of the aperture opening and possible other designs, such as perforations, can already be produced by the printed image.

[0021] According to another advantageous design, the aperture can be formed by a chrome coating printed onto the emission end. A photochemical lacquer can be applied to the chrome coating, which has been exposed in a targeted manner through a mask corresponding to the aperture or aperture opening and possibly other designs, and the aperture opening is etched.

[0022] In a further advantageous manner, the aperture opening can extend at least partially over the fiber core of the optical waveguide and at least partially over the fiber cladding of the optical waveguide.

[0023] In a particularly advantageous manner, the optical waveguide can comprise a multimode optical fiber, preferably a gradient-index optical fiber or a step-index optical fiber. Such optical fibers are very suitable for guiding the light to be analyzed spectrally.

[0024] According to an advantageous embodiment, the optical waveguide and / or the aperture can be oriented in such a way that the obscured measuring light strikes the detector obliquely with respect to the direction of extension of the detector pixels. In other words, the image of the exit end of the optical waveguide can be rotated with respect to the detector pixels in order to thereby improve the intensity distribution detected by the detector pixels. This makes it possible to achieve a particularly effective adjustment of the detector, in particular for special measuring tasks.

[0025] With regard to the method, the object is achieved by the features of claim 16. A method for producing a device according to any one of claims 1 to 12 is proposed, wherein a partially transparent or opaque coating is applied to the exit end of the optical waveguide and wherein the aperture opening is produced by partially removing the coating.

[0026] First of all, it should be pointed out that the device according to the invention and the apparatus according to the invention can also have the features according to the method. The corresponding features and the associated advantages can clearly be part of the method according to the invention. In addition, the features and advantages described with respect to the method according to the invention can also be part of the device according to the invention and the apparatus according to the invention.

[0027] The teaching according to the invention relates in particular to applying the aperture directly to the output end of a particularly ground multimodal optical waveguide, which is preferably held by a ferrule. In particular, if the optical waveguide is surrounded by an accurately centered ferrule, the aperture can be applied to the output end with high precision and high repeatability. Various methods can be used for this purpose.

[0028] In an advantageous embodiment, a partially transparent or opaque coating is first applied to the exit end, and then the aperture opening is exposed by means of a laser ablation process. The great advantage here is that the process can be used very flexibly, since no mask is required for this. Furthermore, the previously applied layer can also be designed partially transparent in places by gradual removal or microperforation, in order to thereby influence the intensity drop in the edge region of the aperture or aperture opening used for imaging.

[0029] In another advantageous embodiment, the aperture can be applied onto the exit end. In particular, if the optical waveguide is surrounded by a ferrule, extremely precise positioning can be achieved by printing, and printing technology is particularly advantageous as a very flexible process.

[0030] In a further advantageous manner, a photolithography process can be used to produce the aperture. First, a chrome layer is applied to the exit end, the photochemical lacquer applied thereto is partially exposed through a mask, and the aperture opening is etched. Individual aperture shapes can also be realized here.

[0031] In general, the following advantages can be achieved through the teachings of the present invention or the above-mentioned advantageous designs: -More flexible component selection: The challenge when designing detectors or spectrometers is that in this extremely dynamic market sector, few components are standardized. For example, there are very few line detectors on the market with the same pixel pitch and pixel aspect ratio, so every discontinuation or change of a component involves complex and cost-intensive changes to the optical design. Due to the very easy adaptability of the aperture geometry, for example by means of a laser ablation process, it is possible to react flexibly to small changes within a limited range, such as different diameters of the optical waveguide and lines with different pixel pitches as well as different pixel heights can be adapted to one another very individually without having to fundamentally change the optical design.

[0032] - Fine adjustment of the slope: Since the diaphragm can be applied directly to the output end of the optical waveguide (e.g. optical fiber), firstly the shape of the diaphragm opening can be designed arbitrarily (elliptical, rectangular, pillow-shaped, ...), and secondly the thickness or microstructure of the applied layer can be influenced, for example, in order to reduce the edge sharpness of the image. This has the advantage that the intensity peaks in the spectrogram can be very narrow, but this does not lead to erroneous situations of insufficient line sampling. Another advantage of directly applying the diaphragm is that the preferably slot-shaped diaphragm opening on the output end can be adjusted (e.g. rotated) in terms of the orientation of the diaphragm opening relative to the detector row, and thus also influence the edge sharpness of the image in a fine-tuned manner.

[0033] - Simple optical design: Since the teaching of the present invention can save the need to significantly reduce the optical imaging ratio, it saves significant costs and increases in space and weight. In addition, the flexibly designed aperture provides greater freedom for optical design, or in other words, provides the possibility of optimizing other parameters.

[0034] - Greater flexibility: Due to the simple production of the diaphragm, in particular by laser ablation, it is possible to respond extremely flexibly to various requirements on the diaphragm, such as the shape of the diaphragm opening. Changing other elements of the device, such as changing the dispersion element, the aperture of the optical waveguide or the diameter of the optical waveguide, or also changing the pixel height or pixel pitch of the detector on the line side, may require adjustment of the diaphragm. Likewise, special shapes, such as a pincushion shape of the diaphragm opening, can also be easily created if necessary.

[0035] Improved stability: With regard to long-term stability, the application of the diaphragm on the emission end is particularly advantageous, since dynamic forces and temperature influences in particular do not affect the exact diaphragm positioning in comparison with a separately arranged diaphragm.

[0036] - No aperture loss: When the aperture is applied directly to the exit end, the available aperture can be fully utilized if the coating is thin enough. When a separate aperture is arranged, the air gap that may exist between the fiber end and the aperture will cause part of the available aperture to remain unused due to the larger exit angle being cut. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] There are now many ways to advantageously design and improve the teaching of the present invention. For this, see on the one hand the dependent claims and on the other hand the following explanation of preferred embodiments of the present invention with the aid of the drawings. In conjunction with the explanation of preferred embodiments of the present invention with the aid of the drawings, generally preferred designs and improvements of the teaching are also explained. Among them: Figure 1 The imaging of the emission end on a line detector with an elongated pixel arrangement and the associated continuous intensity distribution depending on the pixel position are schematically shown; Figure 2 The imaging of another emission end on a line detector with an elongated pixel arrangement and the associated continuous intensity distribution depending on the pixel position are schematically shown; Figure 3 The imaging of another emission end on a line detector with an elongated pixel arrangement and the associated continuous intensity distribution depending on the pixel position are schematically shown; Figure 4 The imaging of another emission end on a line detector with an elongated pixel arrangement and the associated continuous intensity distribution depending on the pixel position are schematically shown; Figure 5 An embodiment of an exit end of a light guide of a device according to the invention is shown schematically; Figure 6 A further embodiment of the exit end of a light guide of a device according to the invention is shown schematically; Figure 7 A further embodiment of the exit end of a light guide of a device according to the invention is shown schematically; Figure 8 A further embodiment of the exit end of a light guide of a device according to the invention is shown schematically; Fig. 9 A further embodiment of the exit end of a light guide of a device according to the invention is shown schematically; and Fig.10 An exemplary embodiment of the device according to the invention is shown in a schematic diagram. DETAILED DESCRIPTION

[0038] Figures 1 to 4 , the beam images 8 falling on the line detector 7 and the intensity distribution 10 received by the line are shown by way of example for different types of apertures. Here, for simplicity, the intensity distribution 10 is shown in a continuous form rather than in a stepped distribution corresponding to discrete scans.

[0039] Figure 1 A line detector 7 is shown, which has narrow detector pixels 9 arranged vertically next to one another. In this case, the circular beam image 8 fills almost the entire line height, so that the detector 7 processes the entire available radiation. In order to reduce the peak width, the "natural" point aperture of the optical waveguide 11 is now shaded by an additional aperture 1 in accordance with the invention, so that the image of the optical waveguide 11 is brought closer to the pixel geometry. Figure 2 Such a shielding with an associated intensity distribution 10 is shown by way of example in . It is also clear here that, with a suitable design with lateral shielding, the peak maximum intensity, which is critical for the exposure time, will remain unchanged and the light loss caused by the aperture 1 only serves to intentionally reduce the peak base.

[0040] Figure 1 An idealized profile of a gradient-index fiber is shown. Here, the point spread function has a Gaussian-like distribution and extends over a large number of marked elongated detector pixels 9. For use in a spectrometer as a confocal chromatic or interferometric distance meter, this profile is too broad, since two or more distances close together would result in an inseparable superposition of the respective measurement peaks.

[0041] like Figure 2 As shown, shielding the exit end 12 of the optical waveguide 11 with an aperture 1 having a slot-shaped aperture opening 4 will result in a very narrow measurement peak that only reaches a few pixel areas. However, if the beam profile is too narrow, several disadvantages will occur. On the one hand, in order to achieve sub-pixel resolution in the confocal measurement method, the illumination of multiple pixels with a sufficient signal-to-noise ratio is essential for a stable center of gravity determination. On the other hand, the detector row has non-active surface areas between the pixels that cannot be underestimated, due to which the risk of intensity drops during detection increases with decreasing signal width. As a result, in the confocal method, signal losses can occur in extreme cases, while in the interferometric measurement method, artifacts can be formed due to the addition of additional oscillations to the measurement signal.

[0042] The ideal width of the diaphragm opening 4 therefore depends on the model-specific pixel pitch and the ratio of active area to inactive area of ​​the line detector 7 as well as the specific requirements for spectral resolution. The width of the diaphragm opening 4, the numerical aperture of the optical waveguide 11 and the manufacturing and adjustment tolerances of the optics installed in the spectrometer lead to variations in the intensity distribution of the optical waveguide 11 imaged on the detector pixel 9. Since the diaphragm 1 is directly connected to the emission end 12 and is usually also embedded in a circular collar, it is possible to rotate this image of the emission end 12 relative to the detector pixel 9 and thus influence the intensity distribution 10 detected by the detector pixel 9 (see Figure 3 ). The rotation slightly widens the base of the peak, so that more pixels are required for the scan, which leads in particular to a more reliable determination of the position of the center of gravity in the confocal measurement method. The peak width in the peak region does not increase as quickly as the peak becomes more prominent.

[0043] Another possibility for using a sufficient number of pixels to determine the pixel position but still achieving the special effect of the peak is to use a partially transparent layer material for the aperture 1 (see Figure 4 ). As a result, a bell-shaped shape several pixels wide stands out. Due to the narrow peak tip, precise positioning can be maintained. A similar effect can also be achieved by perforated opening 6 of diaphragm 1, for example by means of laser ablation. The proposed production method allows precise production of diaphragms of various shapes, some of which are Figures 5 to 9 is shown as an example.

[0044] Figure 5 The diaphragm 1 is shown with a diaphragm opening 4 which is designed as a parallel slot and is attached to the exit end 12 of an optical waveguide 11. For manufacturing reasons, a simple parallel slot can expose not only the fiber core 2 but also the fiber cladding 3. This ensures that the entire aperture available for the slot height is used.

[0045] Figure 6 An aperture 1 is shown with a chamfer 5 at the edge of the aperture opening 4. If the aperture material is not completely sealed optically, the thinning of the gap edge will result in a softer edge image, similar to Figure 4 The effect shown in is similar. When the diaphragm opening 4 is formed by laser ablation, the edge can also be caused by the laser beam.

[0046] An advantageous design of the diaphragm opening 4 can also have a barrel-shaped shape (see Figure 7 ) or a pincushion shape (see Figure 8 ). It is also possible to produce the sharpness of the edge of the aperture opening 4 or the optical tightness of the aperture 1 by means of perforations 6 or microperforations, such as Fig. 9 shown.

[0047] Fig.10 An embodiment of a device according to the invention is shown. The device has a device according to the invention for introducing measuring light, for example as described above Figures 1 to 9 It is important here that the exit end 12 of the optical waveguide 11 with the aperture 1 is arranged in or on the spectrometer 13. The aperture 1 therefore has no influence on the projection of the measuring light onto the measurement object.

[0048] The function of the device is as follows. Illumination light is guided from the light source 14 to the measurement object (not shown) via a part of the optical wave coupler and the lens 15. The measurement light is coupled from the measurement object to the optical waveguide 11 of the optical wave coupler via the lens 15. Via the output end 12 of the optical waveguide 11 arranged in the spectrometer 13, the measurement light is guided to the detector 16 via another optical element if necessary, and the detector 16 is designed as a line detector in this embodiment. In the embodiment shown here, the optical waveguide 11 is part of the optical wave coupler, which is formed by a partial path from the light source to the coupling point, to / from the coupling point of the lens, and to the coupling point of the spectrometer (optical waveguide 11). The coupling point can also be formed by a beam splitter (cube). It is not necessary to design the route between the coupling point and the lens, that is, the common outbound route and return route can be omitted. The optical waveguide 11 of the embodiment shown here can be designed as a fiber melt or fiber polishing coupler. It should be clearly pointed out that the optical paths of the illumination light and the measurement light can also be designed differently. It is only important that the output end 12 of the optical waveguide 11 is arranged on the spectrometer side.

[0049] With regard to further advantageous embodiments of the device according to the invention, in order to avoid repetitions, reference is made to the general part of the description and to the appended claims.

[0050] Finally, it should be explicitly pointed out that the above-described embodiments of the device according to the invention serve only to discuss the claimed teaching and do not restrict it to these embodiments.

[0051] List of Reference Numerals 1 stop 2 fiber cores 3. Fiber Cladding 4 aperture opening 5 Chamfer 6 perforated openings 7-row detector 8-beam image 9 detector pixels 10Intensity distribution 11 Photoconductor 12 Output port 13 Spectrometer 14 Light Source 15 lenses 16 detectors.

Claims

1. A device for conducting measuring light to be spectrally analyzed in a distance and / or thickness measuring system, in particular a confocal chromatic or interferometric distance and / or thickness measuring system, the device comprising an optical waveguide (11), wherein: The optical waveguide (11) has an outlet end (12) for the measuring light, which is preferably held by a ferrule, and is characterized in that an aperture (1) having an aperture opening (4) is arranged on the outlet end (12).

2. The device according to claim 1, characterized in that The diaphragm openings (4) are designed as preferably parallel slots.

3. The device according to claim 1 or 2, characterized in that The diaphragm opening (4) has a shape different from a rectangle, and is in particular designed to be pillow-shaped, barrel-shaped, lens-shaped or elliptical.

4. The device according to any one of claims 1 to 3, characterized in that A perforation opening (6) is formed on the diaphragm (1).

5. The device according to any one of claims 1 to 4, characterized in that The diaphragm opening (4) has a chamfered edge at least in regions.

6. The device according to any one of claims 1 to 5, characterized in that The diaphragm (1) is designed to be partially transparent at least in the edge region of the diaphragm opening (4).

7. The device according to any one of claims 1 to 6, characterized in that The aperture (1) is formed by a coating which is applied to the emission end (12) and is partially transparent or opaque to the measuring light, the coating being composed, for example, of lacquer.

8. The device according to claim 7, characterized in that The coating is partially removed by microablation, laser ablation or mechanically in order to form the aperture opening (4).

9. The device according to any one of claims 1 to 7, characterized in that The aperture (1) is formed by a chrome coating printed onto the exit end (12).

10. The device according to claim 9, characterized in that A photochemical lacquer is applied to the chrome coating, which is partially exposed and forms the aperture opening (4) by etching.

11. The device according to any one of claims 1 to 10, characterized in that The diaphragm opening (4) extends at least partially over the optical fiber core (2) of the optical waveguide (11) and at least partially over the optical fiber cladding (3) of the optical waveguide (11).

12. The device according to any one of claims 1 to 11, characterized in that The optical waveguide (11) comprises a multimode optical fiber, preferably a gradient-index optical fiber or a step-index optical fiber.

13. A device for distance and / or thickness measurement, in particular for interferometric and / or confocal chromatic distance and / or thickness measurement, comprising a device for conducting measuring light according to any one of claims 1 to 12 and a spectrometer (13) with a detector (16) for evaluating the measuring light, wherein: An output end (12) of the optical waveguide (11) is arranged in and / or on the spectrometer (13), the output end having an aperture (1) with an aperture opening (4).

14. The device according to claim 13, characterized in that The detector is designed as a line detector (7) or a multi-line detector.

15. The device according to any one of claims 1 to 14, characterized in that The optical waveguide (11) and / or the aperture (1) are oriented such that the shaded measuring light impinges on the detector obliquely with respect to the direction of extension of the detector pixels (9) of the detector.

16. A method for manufacturing a device according to any one of claims 1 to 12, wherein: A coating which is partially transparent or opaque to the measuring light is applied to the output end (12) of the optical waveguide (11), and the diaphragm opening (4) is produced by partially removing the coating.

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