Apparatus, apparatus and method for confocal color distance and / or thickness measurement

Abstract

The invention relates to a device for confocal coloured, preferably one-dimensional distance and / or thickness measurement, comprising an illumination diaphragm (10) and a confocal coloured optical device, an optical device (21) being arranged between the illumination diaphragm (10) and the confocal coloured optical device, the optical device (21) divides the measurement light emitted from the illumination diaphragm (10) into a plurality of measurement light partial light beams (3, 4), the measurement light partial light beams (3, 4), after passing through the confocal color optical device, are projected on the measurement object at transversely offset measurement points, the probe light partial beam reflected by the measuring point is irradiated onto the receiving diaphragm via a confocal color optical device (1) and an optical device (21), and wherein a common probe light beam is present after passing through the receiving diaphragm. The invention further relates to a device and to a method for confocal colored, preferably one-dimensional, distance and / or thickness measurement.

Description

Technical Field

[0001] The invention relates to a device for confocal chromatic, preferably one-dimensional, distance and / or thickness measurement, comprising an illumination diaphragm, a receiving diaphragm and confocal chromatic optics.

[0002] The invention furthermore relates to a device for confocal chromatic, preferably one-dimensional, distance and / or thickness measurement.

[0003] The invention furthermore relates to a method for confocal chromatic, preferably one-dimensional, distance and / or thickness measurement. Background Art

[0004] Due to the good spatial separability of the measuring head and the advantages of the usually combined sending / receiving / evaluation unit, the confocal chromatic measurement method is often used in areas with explosion hazards, in wet areas, in high vacuum environments or in areas with limited space. The basic structure of a typical confocal chromatic measuring head has an illumination diaphragm and confocal chromatic optics. Due to the dispersion of the confocal chromatic optics, the measuring light of different wavelengths has different focal points from each other. The optical axis of the confocal chromatic optics is collinear with the measuring axis in which the focal group is located. The probe light reflected by the measuring object is imaged onto the receiving diaphragm acting as the confocal diaphragm using the same confocal chromatic optics, and the dominant wavelength of the reflected probe light is determined using a spectrometer. Taking into account the focal lengths of the individual wavelengths, the distance to the measuring object can be determined from the dominant wavelength.

[0005] The problem, however, is that with rough surfaces and predominantly diffusely scattering materials, many measurement uncertainties arise, which are reflected in interfering, position-dependent “noise”. Summary of the invention

[0006] Therefore, the object of the present invention is to design and improve the device and apparatus for confocal chromatic distance and / or thickness measurement so that the improved measurement can be achieved using a simple structure. In addition, an improved method for confocal chromatic distance and / or thickness measurement will be proposed.

[0007] According to the invention, the above-mentioned object with respect to the device is achieved by the features of claim 1. A device for confocal chromatic, preferably one-dimensional distance and / or thickness measurement is thus proposed, the device having an illumination aperture and a confocal chromatic optical device, wherein an optical device is arranged between the illumination aperture and the confocal chromatic optical device, wherein the optical device divides the measuring light emitted from the illumination aperture into a plurality of measuring light partial beams, wherein the measuring light partial beams, after passing through the confocal chromatic optical device, strike the measuring object at laterally offset measuring points, wherein the probe light partial beams reflected by the measuring points strike the receiving aperture via the confocal chromatic optical device and the optical device, and wherein a common probe light beam is present after passing through the receiving aperture.

[0008] The above-mentioned object with respect to the device is achieved by the features of claim 15. A device for confocal chromatic, preferably one-dimensional distance and / or thickness measurement is thus proposed, which has a device according to any of claims 1 to 14, a light source, in particular polychromatic, for emitting measuring light, a spectrometer and an evaluation device. The detector can have a detector row. In addition, coupling points can be arranged to separate the reciprocating paths of other modules.

[0009] The above-mentioned object with regard to the method is achieved by the features of claim 16. A method for confocal chromatic, preferably one-dimensional distance and / or thickness measurement is proposed, in particular with a device according to any of claims 1 to 14 or with an apparatus according to claim 15, wherein measuring light from an in particular polychromatic light source is guided via an illumination aperture to an optical device, wherein the measuring light is divided by the optical device into a plurality of measuring light partial beams and guided to the confocal chromatic optical device, wherein the measuring light partial beams emerging from the confocal chromatic optical device impinge on the measured object at laterally offset measuring points, wherein the probe light partial beams reflected from the measuring points impinge via the confocal chromatic optical device and the optical device on a receiving aperture, wherein after passing the receiving aperture the common probe light beam is transmitted to a spectrometer, wherein an additive spectrally coded measuring signal of the measuring points is generated.

[0010] According to the invention, it has been found that if a confocal color measurement of the measurement object is carried out simultaneously at a plurality of measurement points, local measured value disturbances can be reduced by optical averaging. In particular, only one added measurement signal can be evaluated on a single detector or spectrometer. Furthermore, it is sufficient to arrange a single confocal color optical system.

[0011] According to another embodiment of the invention, the distances of a plurality of measuring points in a small area are averaged optically and absolutely synchronously, wherein the detection area can lie in the range of, for example, a few tenths to a few hundredths of a millimeter in diameter. Another advantage of the invention is that it can be easily applied to existing confocal chromatic measurement systems, since there is no or only a small influence on the system design. The light source can advantageously be a white light source.

[0012] According to the teaching of the invention, instead of the usual one chromatic continuously tuned focus group, a plurality of individual focus groups equal to the number of measuring light partial beams are generated. Due to this special optical arrangement, the color-coded measuring reflections of the individual measuring beams are all projected onto the receiving diaphragm via the corresponding optical paths. The illumination diaphragm and the receiving diaphragm can be formed by a single or common component. Alternatively, it is conceivable that the receiving diaphragm and the illumination diaphragm are different components. In such a design, the receiving diaphragm and the illumination diaphragm are actually at least substantially in the same optical position. It is also important that the receiving diaphragm can be used as a confocal diaphragm (spatial filter), i.e. the receiving diaphragm is located at the focal point on the front side of the confocal chromatic optics and suppresses wavelengths whose wavelength-dependent focal points are located in front of or behind the measurement object.

[0013] If the individual measuring points have a similar backscattering behavior (which is assumed in the case of the small lateral measuring point spacings mentioned above), the superposition of the individual reflections results in an additive spectrally encoded intensity signal. If the intensities are approximately the same in the case of similar backscattering behavior, then it can be said that this is almost an arithmetic average. At measuring points with locally different reflection properties, for example at hard edges or material transitions that are smaller than the lateral measuring point spacing, a weighting component that differs according to the intensity is specified for the average value, so that the measuring point with the best reflection behavior is emphasized in the optical average.

[0014] A high signal-to-noise ratio (SNR) is essential for the reproducibility and stability of distance measurements. With regard to the teaching according to the invention, this means that the shape and direction of the light lobe reflected from the measurement object in combination with the numerical aperture of the objective lens decisively shapes the SNR. This applies in particular to rough surfaces with pronounced local height differences and / or abrupt contour sides. Since the reflected component that can be received by the confocal chromatic optics decreases with increasing angle between the measurement axis and the surface normal of the illuminated measurement object area, the signal-to-noise ratio is subject to strong fluctuations in such contour measurements. If the SNR drops below a set limit value, the measurement point is completely invalid. This signal-to-noise and signal failure can be significantly improved with the invention, since the measurement is carried out simultaneously at multiple measurement points or measurement positions that are closely adjacent to each other.

[0015] The individual signals can be optically accumulated in an advantageous manner so that those signals from measuring points with a good SNR form the greatest contribution, so that these signals compensate for signals with a poor SNR or even failed back reflections. As a result, the probability of at least one good back reflection is many times higher, and the failure rate on surfaces with unsuitable reflection properties is correspondingly reduced. In addition, by optical averaging, invalid measured values ​​are only noticed through their contribution to the background noise of the added measurement signal. This gives the averaging a weight that is related to the intensity of the back reflection from the measurement position. However, the advantage of the fail-safe signal is accompanied by an uncertainty in the lateral position assignment, because it is not possible to determine which of the measuring points closely spaced from each other is signal dominant.

[0016] Another advantage of optical averaging is synchronization. This avoids the clock rate reduction of the block-by-block mathematical average or the time delay of the sliding average. Since only the average intensity distribution from multiple measuring points is present at the receiver, the rows of the detector can be better utilized. In addition, only one correspondence table or one correspondence function between distance and wavelength is required.

[0017] Furthermore, many measurement objects have a microstructure with peak and valley widths that are larger than the usual measurement spot diameter of a confocal color sensor. This can lead to topographic signal noise, which in many cases is undesirable for users of measurement technology. By means of the teaching according to the invention, a synchronous optical multi-point measurement can be achieved, so that these extreme peaks and valleys of the surface of the measured object are equalized, which leads to a signal with a better SNR. In other words, it is possible to adapt the design to the microstructure of the application, i.e. the number and distance of the individual measuring points can be ideally adapted to the microstructure to be measured in order to obtain an optimal average.

[0018] Furthermore, the measurement of the side surfaces of microstructures (e.g. ground surfaces) on predominantly directly reflecting materials can lead to serious errors, since only a small amount of light enters the aperture of the measuring objective due to the too steep reflection angle, resulting in a correspondingly low signal-to-noise ratio. By averaging a number of measuring points, "missing" measurements of such edges can most likely be compensated by simultaneous measurements of well-aligned elevations in adjacent areas.

[0019] Since a virtual multi-point aperture can be generated from a single-point aperture of the measuring light by means of an optical device, the fiber connection on a conventional confocal chromatic lens can be modified without any problems using an adapter. In addition, since all partial signals are optically superimposed, only one measurement peak is displayed on the spectrometer. If the measurement is carried out on a correspondingly large platform, the partial signals will form a broadened signal and the platform will therefore be polished in terms of measurement technology due to averaging. However, if the platform is so large that two distinguishable peaks are formed in the spectrum diagram, even a simultaneous differential measurement can be carried out. Instead of a platform, the thickness of a transparent measurement object can also be determined here. Otherwise, it can be concluded that the invention fully meets the conditions for compatibility with existing systems. Since the invention can be used in conjunction with conventional lenses and spectrometers, the lower costs of this flexible feature also result.

[0020] For optical averaging of a plurality of measuring positions, it is sufficient to add an optical device between the illumination stop and the associated confocal chromatic optics. The coupling point for the incoming measuring light and the outgoing color-coded detection light can be located in front of the illumination stop. The illumination stop and / or the receiving stop can be realized, for example, by an optical shielding element. This design is advantageous if the coupling point is realized by a beam splitter or a beam splitter cube. It is also conceivable that the illumination stop and / or the receiving stop are formed by the fiber ends of an optical waveguide. This is advantageous if an optical waveguide is used between the coupling point and the confocal chromatic optics so that its fiber ends form the illumination stop or the receiving stop.

[0021] The measuring light emitted from the illumination aperture is divided into a plurality of measuring light partial beams by an optical arrangement which may have one or more optical elements. The measuring light partial beams can be incident on the confocal chromatic optical device as divergent measuring light partial beams. According to a further advantageous embodiment, the measuring light partial beams can be focused individually onto a virtual surface located in front of the confocal chromatic optical device. The virtual surface can advantageously coincide with the focus or focal plane of the confocal chromatic objective.

[0022] In an advantageous manner, the optical device can have at least one optical element, in particular a refractive optical element and / or a diffractive optical element (DOE) and / or a meta-optical element (MOE). Specifically, the optical element can be a roof prism and / or a microlens assembly and / or an optical pyramid, preferably a regular pyramid or a rectangular pyramid. In the design of the optical device that generates a measurement light partial beam without an intermediate focus, the measurement light can be divided into a plurality of measurement light partial beams by means of a roof prism or a straight, regular, preferably rectangular pyramid. These measurement light partial beams then pass through the confocal chromatic optical device and are affected by chromatic longitudinal errors, which first makes distance measurement possible. However, contrary to the intended use, these measurement light partial beams impinge on the first objective lens surface at different angles of incidence. This ultimately leads to the extension of the chromatic focus group caused by the confocal chromatic optical device outside the measurement axis, thereby forming a plurality of measurement axes. The reason for this is the change in the angle of incidence of the measurement light partial beams impinging on the confocal chromatic optical device caused by the deflection, because the virtual source point of the measurement light partial beam is offset from the axis due to the inclined surface. Since the larger numerical aperture of the light source due to the beam deflection is received by the confocal chromatic optics and distributed to the measurement points, the sum of the focal areas is greater than the sum of the focal areas of the confocal chromatic optics when it is used for a single measurement point. Therefore, the confocal chromatic optics combined with the optical element may be slightly brighter than the original lens if the original lens did not use the maximum aperture of the confocal diaphragm.

[0023] In another advantageous manner, the optical element can be supplemented with a second optical element, such as a converging lens or a diverging lens. It is conceivable and advantageous that the second optical element is formed integrally with the optical element, or is arranged on the optical element in a materially matched manner, or is printed on the optical element. Alternatively, it is conceivable that the second optical element is integrated into the optical surface of the optical element. For example, the optical surface of the optical element facing the light source can be configured to be flat, and the optical surface facing away from the light source can realize the functions of the optical element and the second optical element in the sense of a complex free-form surface. By means of these construction measures, the received numerical aperture of the illumination diaphragm as well as the lateral position and the measurement spot shape can be adjusted.

[0024] According to an advantageous design, the divergent light of the entrance aperture can initially be almost collimated by means of an optical device, in particular by means of a first optical surface of an optical element. Furthermore, it is conceivable that the collimated total aperture is almost completely divided into a plurality of subapertures by means of a microlens assembly, i.e. a plurality of microlenses placed closely adjacent to each other, and each is refocused onto a common virtual surface. Depending on the design of the confocal chromatic optics and the measuring surface, the focal plane can also be curved if necessary. Such an arrangement can be understood as a division of a primary light source into a plurality of secondary light sources, i.e., images of the receiving aperture. Therefore, the size of the secondary light area and the aperture of the secondary light depend on the beam shaping of the optical element. The advantage of such a division of the primary light source into a plurality of secondary light sources using the proposed construction is that the expansion in the system remains without any necessary influence in the direction of the light source, because the radiation power of the primary light source is distributed to the secondary light source almost without loss. In order to improve the distance resolution of the measuring system, in addition to improving the signal-to-noise ratio, it is also very effective to reduce the measurement peak width in the spectral diagram. When the aperture of the primary light source is divided into sub-apertures and they are respectively focused onto the area of ​​the virtual secondary light source, as described above, the virtual secondary light source has a smaller extension range or spot size than the primary light source.

[0025] In order to exclude the intensity drop in the edge areas when illuminating the confocal chromatic optical devices, their optical design can be designed as follows: these optical devices only evaluate a partial area of ​​the theoretically available aperture of the illumination beam. Since a plurality of secondary light sources are formed from a primary light source when a microlens assembly is used in the optical device, various parameters can be changed. Thus, for example, a larger part of the numerical aperture of the primary light source can be used, whereby these optical devices will ultimately make the overall light intensity stronger when the same confocal chromatic optical devices are used. Alternatively, the numerical aperture of the partial beam of measuring light can be different from the numerical aperture set for the confocal chromatic optical devices. As a result, the target parameters of the measuring point can also be changed, so that the optical device can achieve additional flexibility in adapting to the measurement task.

[0026] Since the microlenses are cleverly arranged over the entire area of ​​the fiber aperture, almost the entire flux of the measuring light can be directed to the measurement object. Although the individual intensities of many measuring points have only a corresponding fraction of the intensities of conventional devices, the total signal after reorganization of the individual channels has a signal intensity similar to that of conventional devices or conventional measuring heads.

[0027] In a particularly advantageous manner, the lateral distance of the measuring point axis can be varied by slight changes to this optical element, which is otherwise independent of the measuring objective, which can be particularly advantageous due to the emerging production of additional lenses.

[0028] Since the mutual crosstalk of the individual measurement channels leads to a broadening of the peak of the total measurement signal, it is advantageous to improve the lateral resolution (x direction) and the depth resolution (z direction). For this purpose, shielding of the central area of ​​the focused beam can be advantageously adopted. This utilizes the fact that at the focus, the depth of field of the edge beam is significantly smaller than the depth of field of the light beam near the axis due to the obtuse angle of incidence. By shielding these light beams close to the axis, a significantly shorter depth of field can be achieved at the expense of lower light intensity. The smaller the depth of field, the higher the separation accuracy that can be achieved in the focal group, which can be observed by the significantly narrower peak in the spectrum diagram. In an advantageous manner, the measuring light partial beam of the measuring light partial beam close to the axis can therefore be shielded by an optical device. The central shielding of the measuring light partial beam can be achieved by covering the optical device or one or more optical elements of the optical device at a critical point with an opaque layer (for example, with chrome or paint). If a microlens assembly is provided in the optical device, this design is particularly advantageous.

[0029] Furthermore, it is conceivable to deflect the partial beams of measuring light near the axis into the edge region of the confocal chromatic optical device or outside it, so that they are suppressed for imaging according to the principle of beam trapping. This will also achieve a central obstruction. For this purpose, the focusing lens of the optical device can have a beam deflection surface in the core region near the axis or can be interrupted by a beam deflection surface. For this purpose, complex surface structures different from conventional optical devices may be required. Alternatively, this partial beam deflection can also be achieved by a special design of a diffractive optical element (DOE) or a meta-optical element (MOE). A ring lens or only a fragment of a ring lens can also be arranged in the optical device to produce a central obstruction.

[0030] In a particularly advantageous manner, the optical device can have an optical element with a plurality of lens segments, wherein a central lens segment located in a central region and an edge lens segment located in an edge region are arranged, and wherein the central lens segments respectively deflect the measuring light incident thereon, so that the measuring light is superimposed with the measuring light deflected by the edge lens segment and forms a common measuring light partial beam. The advantage is that, compared with central shielding, a large amount of light from the central region that is respectively shielded or deflected can be used. In other words, a clever nesting or penetration of the lens segments can be achieved so that light from unused lens areas can be used for imaging into adjacent areas. The plan view of the lens segments nested in each other can present a regular pattern, but also an irregular pattern. In a design variant, by changing the number or size of the segmented surfaces belonging to the focus, for example, the virtual secondary light source can be intensity-weighted. Basically, when the lens segments are arranged, it is advantageous that the distribution of the light beams that together form the secondary light source in the virtual plane is spatially balanced and follows symmetry. This counteracts the different tilt characteristics of the individual measuring axes and thus prevents a tilt-dependent intensity weighting and thus different weightings in the optical average over the individual measuring axes in the case of a linked illumination and imaging beam path.

[0031] The explained penetration of the microlens segments can also be achieved by an optical arrangement which generates diverging partial beams of measuring light. Although this design variant has clear advantages, it also has limitations depending on the target parameters, so that one of the other designs may be more advantageous.

[0032] Overall, the virtual shielding of the central beam near the axis offers two advantages at the same time. On the one hand, the solid angle provided by the primary light source is not divided into smaller solid angles by small microlenses arranged next to each other, but the almost complete solid angle provided is utilized by nesting lens segments of significantly larger theoretically overlapping lenses. As a result, the numerical aperture of the virtual secondary light source is significantly smaller than that of the primary light source. This is reflected in the already narrow measurement peaks in the spectral diagram. On the other hand, by such nesting of segments of large lenses, the central region of each light beam is omitted. It has been recognized here that the average numerical aperture of the central shielded light beam is significantly higher than the average numerical aperture of the unshielded light beam. This leads to a significantly smaller depth of field and therefore a higher chromatic separation accuracy, resulting in significantly narrower measurement peaks. Therefore, penetrating microlens arrays have great advantages for distance resolution.

[0033] Furthermore, it should be pointed out that the features of the device according to the invention and the apparatus according to the invention can also be formulated in terms of methods. The combination of these features with features relating to method claims is not only possible but also advantageous. Likewise, the features of the method according to the invention can also have constructive formulations. The combination of these features with features relating to device claims and / or apparatus claims is not only possible but also advantageous. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] There are now many ways to advantageously design and improve the teaching of the present invention. For this, reference is made on the one hand to the claims dependent on claim 1 and on the other hand to 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 is a schematic diagram of an embodiment of an apparatus according to the present invention; Figure 2 is a schematic diagram of another embodiment of an apparatus according to the present invention; Figure 3 is a schematic diagram of an apparatus according to the prior art; Figure 4 is a schematic diagram of an embodiment of an apparatus according to the present invention; Figure 5 is a schematic diagram of another embodiment of the device according to the present invention; Figure 6 is a schematic diagram of another embodiment of the device according to the present invention; Figure 7 is a schematic diagram of another embodiment of the device according to the present invention; Figure 8 is a schematic diagram of another embodiment of the device according to the present invention; Fig. 9 is a spectrum diagram of a device according to the present invention, wherein wavelength is plotted against intensity; Fig.10 is a spectrum diagram of a device according to the present invention, wherein wavelength is plotted against intensity; Fig.11 is a spectrum diagram of a device according to the present invention, wherein wavelength is plotted against intensity; Fig.12 is a spectrum diagram of a device according to the present invention, wherein wavelength is plotted against intensity; Fig.13 An embodiment of an optical device is shown; Fig.14a , b each show an embodiment of an optical device; Fig.15a, b, c each show an embodiment for arranging square lens segments; and Fig.16a , b each show an embodiment of an optical device. DETAILED DESCRIPTION

[0035] Figure 1 An embodiment of a device according to the invention is shown. It has a light source 20 which emits measuring light, which is guided by an optical coupling element 22 (e.g. a beam splitter or a beam splitter cube or a fiber coupler) to an illumination aperture 10 (e.g. an optical shielding element). The illumination aperture 10 also serves as a receiving aperture 28. An optical waveguide 23 can also be provided, the free end of which can realize the illumination / receiving aperture 10, 28, so that no optical shielding element needs to be provided.

[0036] In addition, an optical device 21 is provided, which divides the measuring light into a plurality of measuring light partial beams 3, 4, which impinge on the confocal chromatic optical device 1, so that the plurality of measuring light partial beams 3, 4 impinge on the measuring object 24 at different measuring points. The probe light beam reflected by the measuring object 24 is guided through the confocal chromatic optical device 1, the optical device 21 and the receiving aperture 28, and if necessary, is guided by the light guide 23 to the optical coupling element 22, and from there to the spectrometer 25. The spectrometer 25 preferably has only a single measuring line. The signal of the spectrometer 25 is evaluated by the evaluation unit 26. In addition, a controller 27 is provided for controlling the individual components.

[0037] Thus, a large number of individual focus groups, which are equal to the number of measurement light partial beams 3, 4, are generated by the confocal chromatic optical device 1, instead of the usual colored continuously tuned focus groups 7. The color-coded detection light partial beams are all reflected back via the corresponding beam paths to the illumination / receiving apertures 10, 28. Due to the small lateral measurement point spacing of the measurement light partial beams 3, 4, it is assumed that the individual measurement points have a similar backscattering behavior and the superposition of the individual reflections results in an accumulated spectrally coded intensity signal, so that there is a synchronous optical averaging.

[0038] Figure 2 An embodiment of the device according to the invention is shown. The device substantially corresponds to Figure 1 The essential difference is that the optical device 21 is designed such that the measuring light partial beams are each focused onto a virtual surface 13 located in front of the confocal chromatic optical device 1 .

[0039] Figure 3A schematic diagram of a device for confocal chromatic distance and thickness measurement according to the prior art is shown. The device has an illumination / receiving aperture 10, 28 and a confocal chromatic optical device 1. Furthermore, focal points 5, 6 with different wavelengths are shown. The optical axis of the confocal chromatic optical device 1 is colinear with the measuring axis 7, on which the focal point group is located.

[0040] Figure 4 A schematic diagram of another embodiment of a device according to the invention is shown, which has an illumination / receiving diaphragm 10, 28, an optical device 21 and a confocal chromatic optical system 1, the optical device having an optical element 11. The aperture of the light beam emerging from the illumination diaphragm 10 is split into a plurality (here: two) of measuring light partial beams 3, 4 by the optical element 11 and each is chromatically processed by the confocal chromatic optical system 1. The focus groups generated on the measuring axes 8, 9 are close to each other.

[0041] Figure 5 A schematic diagram of another embodiment of the device according to the invention is shown, which has an illumination / receiving diaphragm 10, 28, an optical device 21 and a confocal color optical device 1. The optical device 21 has a Figure 4 A further optical element 12 having another beam-forming property is provided adjacent to the optical element 11. This makes it possible—independently of the confocal chromatic optical device 1—to influence the amount of light and the measurement spot size.

[0042] Figure 6 A schematic diagram of another embodiment of a device according to the invention is shown, which has an illumination / receiving aperture 10, 28, an optical device 21 and a confocal chromatic optical device 1. The measuring light 15 is generated by the optical device 21, which is realized as a microlens assembly 14, and is divided into a plurality of measuring light partial beams 3 and each of them is focused. These focal points are located in the virtual surface 13, the shape of which can be flat or curved due to the individual lenses. This allows the shape of the measuring surface to be influenced as necessary. The focal points are like secondary light sources, and the same optical device is used for each focal point. As a result, the color situation of the individual focus groups 8, 9 is extremely similar.

[0043] Figure 7A schematic diagram of another embodiment of a device according to the invention is shown, which has an illumination / receiving aperture 10, 28, an optical device 21 and a confocal chromatic optical device 1. The optical device 21 has a microlens assembly 18. The measuring beam emitted by the light source 10 is divided into several beams by the microlens assembly 18 of the optical device 21, each of which is projected onto a lens segment 16. Since these lens segments 16 each have only the surface curvature of a segment formed by the edge region of a complete lens, the central region can be occupied by adjacent lenses. As a result, the central region of the lens 17 to be suppressed is used for the virtual focus of the adjacent beams. As a result, the measuring light partial beams 3, 4 focused on the virtual surface 13 are blocked in the middle, which can be seen by the blocked area 19. It is important here that the light in the central region is not discarded, but is used for imaging into the adjacent region, so that the amount of light used in the measuring light is higher than the usual central shielding. Therefore, this is a virtual central shielding, in which the partial beams are shielded in the middle, but not the sum of the partial beams is shielded. This improves the depth resolution on the one hand, and also significantly reduces the crosstalk between the individual channels.

[0044] Figure 8 A schematic diagram of a further exemplary embodiment of a device according to the invention is shown, which has an illumination / receiving diaphragm 10, 28, an optical system 21 and a confocal chromatic optical system 1, which has an optical element 11. Figure 4 In this embodiment, the measuring light is divided into two measuring light partial beams by an optical element 11. In order to shield the central area 19 without loss, both surfaces above and below the optical axis 2 in the central area 19 are interrupted by opposing elements. The central beam portions are guided to different target areas by these opposing optical elements. For the sake of clarity, only the beams belonging to the common measuring axis are shown.

[0045] Fig. 9 A spectrogram of a device according to the invention is shown, in which the wavelength (λ) is plotted against the intensity (I). During light averaging, two light signals are combined in one channel, whereby the first signal a together with the second signal b generates a cumulative spectrogram c. If the center of gravity of the signal is determined, it corresponds to the average of the centers of the individual signals, but weighted by the overall intensity.

[0046] Fig.10 A spectrum diagram of a device according to the invention is shown for qualitative comparison with the signal intensity (I) plotted against wavelength (λ).

[0047] Spectrum a was created using an optical setup with a quadrangular pyramid structure, where a high noise level d and a large peak width e can be seen.

[0048] The spectrum a' was created using an optical setup with a microlens assembly, where a reduced noise level d and a smaller peak width e can be seen.

[0049] The spectral graph a'' was created using an optical setup with nested lens segments with a virtual central mask.

[0050] Fig.11 The spectrum is shown as measured on a platform. If the platform is too small, optical averaging over a number of measuring positions will inevitably lead to marginal wear and tear on the measuring technique. To simplify the illustration, the diagram is simplified to two measuring axes.

[0051] Fig.12 The spectrogram measured on a large platform is shown. Since there are sufficient height differences between the individual distances, a distinction is made in the spectrogram. This even makes it possible to permanently determine the height difference of the platform or the thickness of an object.

[0052] Fig.13 An embodiment of an optical element 11 of an optical device 21 is shown. The optical element is implemented as an optical element 11 in the shape of a quadrangular pyramid.

[0053] Fig.14a , b each show an embodiment of the optical element 11 of the optical device 21 . Fig.14a Specifically, a fragment of a lens with the central region omitted is shown in the top view. Fig.14b In the figure, a fragment from the edge region of the convex lens can be seen in the three-axis view.

[0054] Fig.15a , b, c each show an embodiment for arranging square lens segments. The four squares each represent four lens segments. The colored related circular surface located in the center of each group represents the focus in the depth generated by the lens. The lens segments can also have other geometric shapes, such as circles or hexagons.

[0055] Fig.15a This is an example of an assembly of four lens segment groups nested within one another, with which an unlimited nesting is possible.

[0056] Fig.15b A seamlessly nested assembly of 16 measuring points is shown, which can be expanded infinitely.

[0057] Fig.15c This involves a dense nesting of five lens groups. However, this efficient use of a circular aperture cannot be extended without loss.

[0058] Fig.16a , b each show an embodiment of an optical device. Fig.16a It involves a microlens assembly 16 with completely separated apertures. Fig.16bThis is a microlens assembly 16 in which lens segments are arranged in a penetrating manner.

[0059] With regard to further advantageous designs 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.

[0060] 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 limit it to these embodiments.

[0061] List of Reference Numerals 1 Confocal color optics 2 optical axes 3 Measurement light partial beam 4 Measurement light partial beams 5 Focus 6 Focus 7 Axis of the axial focal group 8 eccentric measuring point groups on the axis 9 eccentric measuring point groups for the axis 10 Illumination aperture 11Optical Elements 12 Optical elements 13. Virtual Surface 14 Micro lens assembly 15 main beams 16 Lens Clips 17 Lens fragments of adjacent areas 18 Micro lens assembly 19Obscured Areas 20 Light Source 21 Optical Devices 22 Optical coupling elements 23 fiber optic cables 24Measurement objects 25 Spectrometer 26 evaluation units 27 Controller 28 receiving aperture a Spectrum b Spectrum c Cumulative spectrum dNoise level

Claims

1. A device for confocal chromatic, preferably one-dimensional distance and / or thickness measurement, comprising an illumination diaphragm (10) and confocal chromatic optics, wherein: An optical device (21) is arranged between the illumination aperture (10) and the confocal chromatic optical device, wherein the optical device (21) divides the measuring light emitted from the illumination aperture (10) into a plurality of measuring light partial beams (3, 4), wherein the measuring light partial beams (3, 4) impinge on a measurement object (24) at laterally offset measuring points after passing through the confocal chromatic optical device, wherein the detection light partial beams reflected by the measuring points impinge on a receiving aperture via the confocal chromatic optical device (1) and the optical device (21), and wherein a common detection light beam is present after passing through the receiving aperture.

2. The device according to claim 1, characterized in that The illumination aperture (10) and / or the receiving aperture are formed by optical fiber ends of an optical waveguide (23) and / or by at least one optical shielding element.

3. The device according to claim 1 or 2, characterized in that: The illumination aperture (10) and the receiving aperture are formed by a common component.

4. The device according to any one of claims 1 to 3, characterized in that The optical device (21) has at least one optical element (11), in particular a refractive optical element and / or a diffractive optical element and / or a meta-optical element.

5. The device according to claim 4, characterized in that The optical element (11) is a roof prism and / or a microlens assembly (14, 18) and / or an optical quadrangular pyramid, preferably a regular quadrangular pyramid or a rectangular quadrangular pyramid.

6. The device according to claim 4 or 5, characterized in that The optical element (11) is supplemented by a second optical element (12), for example a converging lens or a diverging lens.

7. The device according to claim 5, characterized in that The second optical element (12) is formed as one piece with the optical element (11), or is arranged on the optical element (11) in a material-fitting manner, or is printed on the optical element (11), or the second optical element (12) is integrated into an optical surface of the optical element (11).

8. The device according to any one of claims 1 to 7, characterized in that The optical device (21) focuses each of the measuring light partial beams (3, 4) onto a virtual surface, in particular a curved surface, located in front of the confocal chromatic optical element.

9. The device according to claim 8, characterized in that The virtual surface (13) is located at the focus of the confocal chromatic optics.

10. The device according to any one of claims 1 to 7, characterized in that The optical device (21) divides the measuring light emitted from the entrance aperture into diverging measuring light partial beams (3, 4).

11. The device according to any one of claims 1 to 10, characterized in that The measuring light partial beams (3, 4) close to the axis are shielded by the optical device (21), in particular by covering at least one optical element (11, 12) with an opaque layer, for example comprising chrome or lacquer.

12. The device according to any one of claims 1 to 11, characterized in that The measuring light partial beams (3, 4) close to the axis can be deflected by the optical device (21) so that the measuring light partial beams (3, 4) close to the axis do not strike the confocal chromatic optical device (1) and / or strike only in the edge region.

13. The device according to any one of claims 1 to 12, characterized in that The focusing lens of the optical device has a beam-deflecting surface in a core region close to the axis and / or is interrupted by said surface.

14. The device according to any one of claims 1 to 13, characterized in that The optical device (21) has an optical element (11, 12) with a plurality of lens segments (16), wherein a central lens segment (17) is arranged in a central region and an edge lens segment is arranged in an edge region, and wherein the central lens segment (17) deflects the measuring light incident thereon in each case so that the measuring light is superimposed with the measuring light deflected by the edge lens segment and forms a common measuring light partial beam (3, 4).

15. A device for confocal chromatic, preferably one-dimensional distance and / or thickness measurement, comprising a device according to any one of claims 1 to 14, a light source (20), in particular a polychromatic light source (20) for emitting measuring light, a spectrometer (25) and an evaluation device.

16. A method for confocal chromatic, preferably one-dimensional, distance and / or thickness measurement, in particular carried out with a device according to any one of claims 1 to 14 or with a device according to claim 15, wherein: Measuring light from a particularly polychromatic light source (20) is guided through an illumination aperture (10) to an optical device (21), wherein the measuring light is divided by the optical device into a plurality of measuring light partial beams (3, 4) and guided to a confocal chromatic optical device (1), wherein the measuring light partial beams (3, 4) emitted from the confocal chromatic optical device impinge on the measured object (24) at laterally offset measuring points, wherein the probe light partial beams reflected from the measuring points impinge via the confocal chromatic optical device (1) and the optical device (21) on a receiving aperture, wherein after passing through the receiving aperture the common probe light beam is transmitted to a spectrometer (25), wherein an additive spectrally coded measuring signal of the measuring points is generated.

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