Common focus chromatic aberration type distance and / or thickness measuring apparatus and measuring method thereof

Abstract

The present invention relates to a one-dimensional confocal chromatic aberration type distance and / or thickness measuring device having an illumination aperture (10) and a confocal chromatic aberration type optical system (1), wherein an optical device (21) is disposed between the illumination aperture (10) and the confocal chromatic aberration type optical system (1), the optical device (21) divides measurement light emitted from the illumination aperture (10) into a plurality of partial beams (3, 4) of the measurement light, and after the plurality of partial beams (3, 4) of the measurement light pass through the confocal chromatic aberration type optical system (1), they hit a measurement object at a plurality of measurement points offset in the lateral direction, and a plurality of partial beams of detection light reflected from the plurality of measurement points hit a light receiving aperture (28) via the confocal chromatic aberration type optical system (1) and the optical device (21), and after passing through this light receiving aperture (28), they become a single common detection light beam, and relates to a distance and / or thickness measuring device. The present invention relates to a one-dimensional confocal chromatic aberration type distance and / or thickness measuring device and a measuring method.

Description

[Technical Field]

[0001] The present invention relates to a one-dimensional confocal color difference distance and / or thickness measuring device having an illumination diaphragm, a receiving diaphragm and a confocal color difference optical system.

[0002] Furthermore, the present invention relates to a one-dimensional confocal color difference distance and / or thickness measurement device.

[0003] Furthermore, the present invention relates to a one-dimensional confocal color difference distance and / or thickness measurement method. [Background technology]

[0004] Confocal color difference measurement methods are often used in explosive, wet, high-vacuum environments or where space is limited, due to the good spatial separation between the measurement head and the usually integrated transmitting / receiving / evaluating unit. The basic structure of a conventional confocal color difference measuring head includes an illumination diaphragm and a confocal color difference optical system. In addition, since the confocal color difference optical system has dispersion, when the wavelength of the measurement light is different, the focus is also different. Here, the optical axis of the confocal color difference optics is collinear with the measurement axis in which the focus group lies. The detected light reflected from the measurement object is detected by the same confocal color difference optical system at a receiving aperture that functions as a confocal stop, and the dominant wavelength of the reflected detected light is determined using a spectrometer. By taking into account the focal length of each wavelength, the distance to the object can be determined from the dominant wavelength.

[0005] However, rough and diffusely scattering materials present a problem of high measurement uncertainty, which is reflected as annoying, location-dependent "noise." Summary of the Invention [Problem to be solved by the invention]

[0006] Accordingly, an object of the present invention is to design and develop a confocal chromatic distance and / or thickness measuring device that enables improved measurements using structurally simple means. Furthermore, an improved distance and / or thickness measurement method in confocal chromatic distance and / or thickness measurement is also specified.

Means for Solving the Problems

[0007] According to the present invention, the above object regarding the device is achieved by the features of claim 1. That is, a one-dimensional confocal chromatic distance and / or thickness measuring device having an illumination aperture and a confocal chromatic aberration optical system, wherein an optical device is disposed between the illumination aperture and the confocal chromatic aberration optical system, the optical device divides measurement light emitted from the illumination aperture into a plurality of partial beams of the measurement light, and after the plurality of partial beams of the measurement light pass through the confocal chromatic aberration optical system, they hit the measurement object at a plurality of measurement points offset in the lateral direction, and a plurality of partial beams of detection light reflected from the plurality of measurement points hit a light receiving aperture via the confocal chromatic aberration optical system and the optical device, and after passing through the light receiving aperture, they become a single common detection light beam, and a distance and / or thickness measuring device is provided.

[0008] Regarding the distance and / or thickness measuring device, the above object is achieved by the features of claim 15. That is, a one-dimensional confocal chromatic distance and / or thickness measuring device according to any one of claims 1 to 14, in particular, having a multi-color light source (20) that emits measurement light, a spectrometer (25), and an evaluation device is provided. The detector may have one detector row. Furthermore, a coupling point may be used to separate the emission path and the return path of another assembly.

[0009] Regarding the distance and / or thickness measurement method, the above object is achieved by the features of claim 16. That is, a one-dimensional confocal chromatic aberration type distance and / or thickness measurement method having the distance and / or thickness measurement device according to any one of claims 1 to 14 or the distance and / or thickness measurement device according to claim 15, wherein measurement light from a multi-color light source is guided to an optical device through an illumination aperture, the measurement light is split into a plurality of partial beams of the measurement light by the optical device and guided to a confocal chromatic aberration type optical system, a plurality of partial beams of the measurement light emitted from the confocal chromatic aberration type optical system hit the measurement object at a plurality of measurement points offset in the lateral direction, a plurality of partial beams of detection light reflected from the plurality of measurement points hit a light receiving aperture through the confocal chromatic aberration type optical system and the optical device, and after passing through the light receiving aperture, a single common detection light beam is supplied to a spectrometer, and a total spectral coded measurement signal at the plurality of measurement points is generated, a distance and / or thickness measurement method is provided.

[0010] According to the present invention, when simultaneously performing confocal chromatic aberration type measurement on a measurement object at a plurality of measurement points, local measurement value interference is reduced by forming an optical average value. In particular, a single detector or spectrometer may evaluate only one total measurement signal. Furthermore, it is sufficient to simply arrange a single confocal chromatic aberration type optical system.

[0011] In a further distance and / or thickness measurement method according to the present invention, the distances between a plurality of measurement points within a small region are optically averaged in an absolutely synchronized manner, and the detection range may be, for example, a region having a diameter of one tenth to one hundredth of a millimeter. A further advantage of the present invention is that it has little or no impact on the system design, and thus can be easily incorporated into an existing confocal chromatic aberration type measurement system. The light source is advantageously a white light source.

[0012] According to the present invention, instead of one focus group that is normally continuously adjusted in terms of color, a plurality of individual focus groups corresponding to the number of partial measurement light beams are generated. Due to this special optical arrangement, all the color-coded measurement reflections of the individual measurement beams are projected onto the light-receiving aperture via the corresponding optical paths. The illumination aperture and the light-receiving aperture may be formed by a single or common component. Alternatively, it is also conceivable that the light-receiving aperture and the illumination aperture are separate components. In such a configuration, the light-receiving aperture and the illumination aperture are optically arranged at substantially the same position. Furthermore, the light-receiving aperture can function as a confocal aperture (spatial filter). That is, the light-receiving aperture is arranged at the front focal point of the confocal chromatic aberration optical system to prevent the generation of wavelengths with wavelength-dependent foci in front of or behind the measurement object.

[0013] When individual measurement points exhibit similar backscattering behavior (which is assumed when the lateral distance between measurement points is small as described above), when the individual reflected lights are superimposed, a total spectral-coded intensity signal is obtained. When the backscattering behavior is similar and the intensities are approximately the same, it can be said that an approximately arithmetic averaging process is being performed. At measurement points with locally different reflection characteristics (for example, when there are hard edges or material transitions smaller than the lateral distance between measurement points), different weighting factors are used for averaging according to the intensity, whereby the measurement points with the best reflection behavior during optical averaging are emphasized.

[0014] A high signal-to-noise ratio (SNR) is extremely important for the reproducibility and stability of distance measurement. In the context of the present invention, this means that the shape and direction of the light rays reflected from the measurement object, together with the numerical aperture of the lens, have a decisive influence on the SNR. This applies to cases of rough surfaces with large local height differences or surfaces with steep profile sides. In a confocal chromatic aberration type optical system, the reflectance component that can be received decreases as the angle between the measurement axis and the surface normal of the irradiation area of the measurement object increases. Therefore, in such shape measurement, the signal-to-noise ratio fluctuates greatly. When the SNR falls below a predetermined threshold value, this measurement point becomes invalid. Such signal noise and signal loss can be significantly improved using the present invention. This is because the measurement is performed simultaneously at a plurality of adjacent measurement points or measurement locations.

[0015] Since the individual signals can be optically added, the signals from the measurement points with good SNR contribute most strongly, and can compensate for signals with poor SNR and signals lacking reflections. That is, the probability of using at least one good reflection is increased many times, and the failure rate of surfaces with inappropriate reflection characteristics is accordingly reduced. With optical averaging, invalid measurements are only considered in terms of their contribution to the background noise of the added measurement signal. Thus, the averaging involves weighting corresponding to the reflection intensity at the measurement position. However, since it is not possible to determine which of the adjacent measurement points is signal-dominant, the advantage of this fail-safe signal is accompanied by uncertainty in the lateral position assignment.

[0016] Another advantage of optical averaging is synchronism. This makes it possible to avoid a decrease in the clock rate in block-based mathematical averaging and a time delay in the case of a moving average. Since the receiver only uses one average intensity profile from a plurality of measurement spots, the detector columns can be utilized more advantageously. Furthermore, there is only one required distance and wavelength assignment table or assignment function.

[0017] Furthermore, many of the measurement objects have a fine structure with a peak width and a valley width larger than the normal measurement spot diameter of a confocal chromatic aberration type sensor. This results in the generation of unwanted shaped signal noise, often for the measurer. The present invention enables synchronous optical multi-point measurement, equalizes these extreme peaks and valleys on the surface of the measurement object, and obtains a signal with a better SNR. In other words, the design can be adapted to the actual microstructure, that is, the number and distance of individual measurement points can be ideally adapted to the microstructure to be measured for optimal averaging.

[0018] Furthermore, in the measurement of the edge of the microstructure of the directly reflecting material (such as a polished surface), since the reflection angle is too steep, only a small amount of light enters the aperture of the measurement lens, and the signal-to-noise ratio is low, so errors are likely to occur. By averaging multiple measurement points, it is highly likely that such "lost" measurement values at the edge are complemented by the measurement values simultaneously measured in the adjacent flat regions of the same height.

[0019] By using an optical device, it is possible to generate a virtual multi-point aperture from a single-point aperture of the measurement light, so the fiber connection can be easily connected to a conventional confocal chromatic aberration lens using an adapter. Since all partial signals are optically superimposed, there is only one measurement peak displayed on the spectrometer. When measuring a large step, the partial signals form a broadened signal, so the step becomes smooth in measurement by averaging. [[ID=2l]]However, when two distinguishable peaks are formed in the spectrogram because the step is very large, synchronous height difference measurement is also possible. Instead of the step, the thickness of the transparent measurement object can also be determined here. In other respects, the present invention fully meets the compatibility conditions with existing systems. Since the present invention can be combined with conventional lenses and spectrometers, the introduction cost of such flexible functions is also low.

[0020] To optically average a plurality of measurement positions, it is sufficient to add an optical device between the illumination aperture and the confocal chromatic aberration optical system associated therewith. The coupling point of the incident measurement light and the outgoing color-coded detection light may be arranged in front of the illumination aperture. The illumination aperture and / or the light receiving aperture may be realized, for example, by an optical aperture element. Such a design is advantageous when the coupling point is realized by a beam splitter or a beam splitter cube. It is also conceivable that the illumination aperture and / or the light receiving aperture are formed at the fiber end of the optical waveguide. This configuration is advantageous when an optical waveguide is used between the coupling point and the confocal chromatic aberration optical system, and the fiber end thereof forms the illumination aperture or the light receiving aperture.

[0021] The optical device has one or more optical elements and splits the measurement light emitted from the illumination aperture into a plurality of partial beams of the measurement light. The partial beams of the measurement light can be directed to the confocal chromatic aberration optical system as partial beams of divergent measurement light. Furthermore, the partial beams of the measurement light may be individually focused on a virtual plane located in front of the confocal chromatic aberration optical system. It is advantageous if the virtual plane coincides with the focal point or the focal plane of the confocal chromatic aberration lens.

[0022] It is advantageous if the optical device has at least one optical element, in particular a refractive optical element, a diffractive optical element (DOE) and / or a meta-optical element (MOE). Specifically, the optical element may be a roof prism, a microlens array and / or an optical pyramid, preferably a regular pyramid or a right pyramid. In the configuration of the optical device that generates partial beams of measurement light without an intermediate focus, the measurement light may be split into a plurality of partial beams of measurement light by a roof prism or a regular pyramid, preferably a right pyramid. Next, these partial beams of the measurement light pass through a confocal chromatic aberration optical system and undergo longitudinal chromatic aberration, enabling the first distance measurement. However, in contrast to the intended use, these partial beams of the measurement light strike the first lens surface at different incident angles. As a result, ultimately, the color focus groups generated by the confocal chromatic aberration optical system pass outside the measurement axis, forming a plurality of measurement axes. The reason is that the virtual light sources of the partial beams of the measurement light are shifted from the axis due to the inclined surface, and the beam is deflected, causing the incident angle of the partial beams of the measurement light to the confocal chromatic aberration optical system to change. Due to this beam deflection, the light source is captured by the confocal chromatic aberration optical system at a higher numerical aperture and distributed to the measurement points. Therefore, the total of the focal regions becomes larger than when the focal chromatic aberration optical system is used for a single measurement point. As a result, when the original lens does not use the maximum aperture of the confocal aperture stop, the confocal chromatic aberration optical system combined with the optical element may function slightly faster than the original lens.

[0023] Furthermore, a second optical element, such as a converging lens or a diverging lens, may be added to the optical element. The second optical element is formed by the optical element and a component, or is disposed in a materially bonded state on the optical element, or is printed on the optical element. Alternatively, the second optical element is incorporated into the optical surface of the optical element. For example, the optical surface of the optical element facing the light source may be flat, and the optical surface away from the light source may function as the optical element and the second optical element in the sense of a complex free-form surface. By these design methods, it is possible to adjust the numerical aperture of the illumination aperture stop used, as well as the lateral position and the shape of the measurement spot.

[0024] According to the embodiment, the divergent light of the incident aperture stop can be made substantially parallel light by the first optical surface of the optical device, particularly the optical element, at first. Furthermore, by means of a microlens array, that is, a plurality of adjacent microlenses, the entire aperture shape for collimating light is almost completely divided into a plurality of sub-aperture shapes, and each of them refocuses on a common virtual plane. Depending on the design of the confocal chromatic aberration optical system and the measurement surface, this focal plane may also be curved. Such an arrangement divides the primary light source into a plurality of secondary light sources, thereby generating an image of the light-receiving diaphragm. Therefore, the size of the secondary light region and the aperture shape of the secondary light depend on the beam shaping of the optical element. The advantage of dividing the primary light source into a plurality of secondary light sources in this way by the proposed design is that the radiating power of the primary light source is divided into a plurality of secondary light sources with almost no loss, so it can be expanded in the system without the feedback effect in the direction of the light source. To improve the distance resolution of the measurement system, in addition to improving the signal-to-noise ratio, it is also very effective to narrow the measurement peak width of the spectrogram. As described above, when the aperture shape of the primary light source is divided into a plurality of sub-aperture shapes and they are individually focused on the region of the virtual secondary light source, the expansion or spot size of the virtual secondary light source becomes smaller than that of the primary light source.

[0025] In order to avoid the intensity reduction in the edge region when irradiating the confocal chromatic aberration optical system, the optical design may be performed so as to utilize only a part of the theoretically available aperture shape of the irradiation beam. When a microlens array is used in an optical device, a plurality of secondary light sources are formed from the primary light source, so various parameters can be changed. For example, the numerical aperture of the primary light source may be used at a higher ratio, whereby the overall speed is improved when using the same confocal chromatic aberration optical system. Alternatively, the numerical aperture of the measurement light beam may be changed from the numerical aperture provided in the confocal chromatic aberration optical system. This makes it possible to finally change the target parameters of the measurement points, and improves the flexibility of the optical device for adapting to the measurement task.

[0026] By skillfully arranging microlenses over the entire aperture surface of the fiber, almost all of the light beam of the measurement light can be directed toward the object to be measured. The individual intensities of a large number of measurement spots only have the intensities of the corresponding parts in the conventional device, but the overall signal after recombining the individual channels has a high signal intensity similar to that of the conventional device or the conventional measurement head.

[0027] In particular, by making small changes to this optical element that is independent of the measurement lens, the lateral distance of the measurement spot axis can be changed, which is particularly advantageous compared to the case of manufacturing additional lenses.

[0028] Due to the mutual crosstalk between the individual measurement channels, the peak of the total measurement signal spreads, thereby increasing both the lateral resolution (x direction) and the depth resolution (z direction). Therefore, it is advantageous to shield the central region of the focused beam. This utilizes the fact that the marginal beams are incident at an obtuse angle to the focus, so the depth of field of the marginal beams is significantly smaller than that of the beams near the axis. By shielding these beams near the axis, a significantly smaller depth of field is achieved at the expense of a decrease in light intensity. The smaller the depth of field, the higher the selectivity achievable in the focus group, and the peaks of the spectrogram become significantly narrower. It is advantageous if an optical device can shield the partial beam near the axis of the partial beam bundle of the measurement light. To shield the center of the partial beam of the measurement light, the optical device or one or more optical elements within the optical device are masked with an opaque layer such as chrome or lacquer at a critical location. Such a design is particularly advantageous when a microlens array is provided in the optical device.

[0029] Furthermore, it is also conceivable to deflect a partial beam of the measurement light near the axis into or outside the edge region of the confocal chromatic aberration optical system to suppress the imaging of these beams according to the principle of the beam trap. As a result, the central part is also shielded. For this purpose, the focusing lens of the optical device may have a beam deflection plane within the core region near the axis, or may be blocked by this plane. This may require a complex surface structure different from the conventional optical system. Alternatively, this partial beam deflection can also be achieved by special design options of a diffractive optical element (DOE) or a meta-optical element (MOE). In addition, in order to shield the central part, only an annular lens or a part of the annular lens may be provided in the optical device.

[0030] In a particularly advantageous method, the optical device has an optical element having a plurality of lens pieces, a plurality of central lens pieces located in the central region and a plurality of peripheral lens pieces located in the edge region are arranged, and each of the plurality of central lens pieces deflects the measurement light hitting itself and overlaps with the measurement light deflected by the edge lens piece to form a partial beam of a single common measurement light. This has the advantage that, in contrast to the shielding of the central part, a large amount of light can be utilized from the shielded or deflected central region. In other words, by skillfully combining or interlacing the lens pieces, the light from the unused lens region can be utilized for imaging in the adjacent region. The combination of the lens pieces may be a regular pattern or an irregular pattern. <s For example, in one design aspect, the intensity of the virtual secondary light source may be weighted by changing the number or size of the sectional screens associated with the focus. In principle, it is advantageous that the arrangement of the lens pieces is such that the distribution of the light rays forming the secondary light source in the virtual plane is spatially balanced and symmetric. As a result, the different inclination characteristics of the individual measurement axes are canceled out, and no intensity weighting depending on the inclination is performed. Therefore, no different weighting is performed in the optical averaging of the individual measurement axes having a consistent illumination and imaging beam path.

[0031] The above-described interlacing of the microlens pieces may be realized using an optical device that generates partial beams of the diverging measurement light. This modified embodiment has obvious advantages, but there are also limitations depending on the target parameters, so in some cases, one of the other embodiments may be more advantageous.

[0032] Overall, there are two advantages to the virtual shielding of the central beam near the axis. On the one hand, the solid angle provided by the primary light source is not divided into small solid angles by a plurality of small microlenses arranged adjacent to each other. However, in each case, almost all parts of the provided solid angle are utilized by interleaving the lens pieces of a fairly large lens that theoretically overlap. As a result, the numerical aperture of the virtual secondary light source is lower than that of the primary light source, but the difference is small. This is reflected in the fact that the measurement peak of the spectrogram is narrow. On the other hand, when the lens pieces of the large lens are interleaved in this way, the central region of each beam cannot be used. It is known that the average numerical aperture of the beam with the central part shielded is significantly higher than that of the beam without shielding. As a result, the depth of field of the subject becomes significantly smaller, the color selectivity becomes higher, and the measurement peak becomes significantly narrower. Therefore, the interlaced microlens array has great advantages in distance resolution.

[0033] Furthermore, it should be noted that the features of the distance and / or thickness measurement device according to the present invention can be embodied as a distance and / or thickness measurement method. It is not only possible but also advantageous to combine these features with those related to the method claims. Similarly, the distance and / or thickness measurement method of the present invention can be implemented constructively. It is not only possible but also advantageous to combine these features with those related to the apparatus claims.

[0034] There are various possibilities for designing and developing the present invention in an advantageous manner. For this purpose, on the one hand, reference is made to the claims that refer to claim 1, and on the other hand, reference is made to the following description of the embodiments of the present invention based on the drawings. Generally, the embodiments and development examples are described in conjunction with the description of the embodiments of the present invention with reference to the drawings.

Brief Description of the Drawings

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Figure 16

Embodiments for Carrying Out the Invention

[0051] Figure 1 shows a distance and / or thickness measuring device according to an embodiment of the present invention. This distance and / or thickness measuring device has a light source 20 that emits measurement light, and this measurement light is guided to an illumination aperture 10 such as a light aperture element by an optical coupling element 22 such as a beam splitter, a beam splitter cube, or an optical fiber coupler. The illumination aperture 10 also functions as a light receiving aperture 28 here. In this case, an optical waveguide 23 may also be provided. In that case, since the illumination / receiving apertures 10 and 28 can be realized at the free end of the optical waveguide 23, there is no need to provide a light aperture element.

[0052] Furthermore, an optical device 21 is arranged to divide the measurement light into a plurality of partial beams 3 and 4 of the measurement light that enter the confocal chromatic aberration optical system 1, whereby the plurality of partial beams 3 and 4 of the measurement light hit different measurement points of the measurement object 24. The detection light beam reflected by the measurement object 24 is guided to the optical coupling element 22 via the confocal chromatic aberration optical system 1, the optical device 21, the light receiving aperture 28, and, if applicable, the optical guiding member 23, and is then guided from there to the spectrometer 25. The spectrometer 25 has only one measurement column. The signal of the spectrometer 25 is evaluated by an evaluation unit 26. Furthermore, a controller 27 for controlling the individual components is provided.

[0053] The confocal chromatic aberration optical system 1 generates a plurality of individual focus groups corresponding to the number of partial beams 3 and 4 of the measurement light instead of one focus group 7 that is normally continuously adjusted in terms of color. The color-coded partial beams of the detection light are all reflected to the illumination aperture 10 / light receiving aperture 28 via the corresponding optical paths. Since the lateral spacing between the measurement points of the partial beams 3 and 4 of the measurement light is small, it is assumed that the backscattering behavior of each individual measurement point is similar. By superimposing the individual reflections, a total spectral coded intensity signal can be obtained, and synchronous optical averaging is performed.

[0054] Figure 2 shows an embodiment of a distance and / or thickness measuring device according to the present invention. Since Figure 2 substantially corresponds to the distance and / or thickness measuring device of Figure 1, for the sake of avoiding repetition, please refer to the above description. The important difference is that the optical device 21 is designed such that the partial beams 3 and 4 of the measurement light are individually focused on a virtual surface 13 located in front of the confocal chromatic aberration optical system 1.

[0055] Figure 3 shows a schematic diagram of a confocal chromatic aberration type distance and thickness measuring device according to the prior art. This distance and / or thickness measuring device has an illumination aperture 10 / a light receiving aperture 28 and a confocal chromatic aberration optical system 1. Furthermore, the foci 5 and 6 are shown at different wavelengths. Here, the optical axis 2 of the confocal chromatic aberration optical system 1 is on the same line as the measurement axis 7 where the focus group is located.

[0056] Figure 4 shows a schematic diagram of a further embodiment of a distance and / or thickness measuring device of the present invention having an illumination / light receiving aperture 10, 28, an optical device 21 having an optical element 11, and a confocal chromatic aberration optical system 1. The light beam emitted from the illumination aperture 10 is split by the optical element 11 into a plurality (here, two) of partial beams 3 and 4 of the measurement light, and each is individually given chromatic aberration by the confocal chromatic aberration optical system 1. The resulting focus groups on the measurement axes 8 and 9 are close to each other.

[0057] Figure 5 shows a schematic diagram of a further embodiment of a distance and / or thickness measuring device of the present invention having an illumination aperture 10 / a light receiving aperture 28, an optical device 21, and a confocal chromatic aberration optical system 1. In addition to the optical element 11 of FIG. 4, the optical device 21 has a further optical element 12 having further beam forming characteristics. Thereby, independently of the confocal chromatic aberration optical system 1, it is possible to affect the amount of light and the size of the measurement spot.

[0058] FIG. 6 shows a schematic view of a further embodiment of the distance and / or thickness measuring device of the present invention having the illumination aperture 10 / receiving aperture 28, the optical device 21, and the confocal chromatic aberration optical system 1. The measurement light 15 is split into partial beams 3 of a plurality of measurement lights by the optical device 21 implemented as a microlens array 14, and each is focused. These foci are located within the virtual plane 13, and the shape of the virtual plane 13 may be planar or curved by individual lenses. Thereby, it is possible to affect the shape of the measurement surface as necessary. These plurality of foci each function like a plurality of secondary light sources using the same optical system. As a result, the color curves of the individual focus groups 8, 9 are very similar.

[0059] FIG. 7 shows a schematic view of a further embodiment of the distance and / or thickness measuring device according to the present invention having the illumination aperture 10 / receiving aperture 28, the optical device 21, and the confocal chromatic aberration optical system 1. The optical device 21 has a microlens array 18. The measurement light beam emitted from the light source 10 is split into a plurality of beams by the microlens array 18 of the optical device 21, and each beam hits the lens piece 16. Each of the lens pieces 16 has only the surface curvature of the edge region of the complete lens, and a plurality of adjacent lens pieces can occupy the central region. As a result, the central region of the lens 17 no longer exhibits its original function and is used as the virtual focus of the adjacent light beams. As a result, the partial beams 3 and 4 of the measurement light focused on the virtual plane 13 are blocked at the center, which can be confirmed by the fact that the central region 19 is dark. It is important that the light from the central region is not lost and is used for imaging in adjacent regions, and thus more light quantity of the measurement light is used than in the conventional central shielding. Therefore, this configuration is a virtual central shielding. The partial beams 3 and 4 are blocked at the center, but the sum of the partial beams 3 and 4 is not blocked. Thereby, on the one hand, the depth resolution is improved, and at the same time, the crosstalk between individual channels is significantly reduced.

[0060] FIG. 8 shows a schematic diagram of a further embodiment of the distance and / or thickness measuring device of the present invention having an illumination aperture 10 / a light receiving aperture 28, an optical device 21 having an optical element 11, and a confocal chromatic aberration optical system 1. According to the embodiment shown in FIG. 4, in this embodiment, the measurement light is split into two partial beams 3 and 4 by the optical element 11. In order to narrow down the central region 19 without loss, each of the two surfaces on the upper and lower sides of the optical axis 2 in the central region 19 is blocked by an element extending in the opposite direction. The central portions of the measurement light partial beams 3 and 4 are directed to another target region by the optical elements extending in these opposite directions. For clarity, only the partial beams 3 and having a common measurement axis are shown.

[0061] FIG. 9 shows a spectrogram of the distance and / or thickness measuring device according to the present invention, where the wavelength (λ) is plotted against the intensity (I). When performing optical averaging, two optical signals are combined into one channel, and the first signal a and the second signal b generate a total spectrogram c. When determining the centroid of this signal, the centroid corresponds to the average of the individual signal centers and is further weighted by the overall intensity.

[0062] FIG. 10 shows a spectrogram of a distance and / or thickness measuring device according to the present invention, qualitatively compared using signal intensity (I) plotted over wavelength (λ).

[0063] Spectrogram a was created using an optical device with a pyramid structure, and a high noise level d and a large peak width e can be seen.

[0064] Spectrogram a' was obtained using an optical device having a microlens array. Here, it can be seen that the noise level d has decreased and the peak width e has become smaller.

[0065] Spectrogram a'' was created using an optical device having interleaved lens segments with virtual central obstruction.

[0066] FIG. 11 shows a spectrogram in the measurement of a step portion. When the step portion is very small, if optical averaging is performed at a plurality of measurement positions, the edge will inevitably become smooth in measurement. For simplicity of the figure, only two measurement axes are shown.

[0067] FIG. 12 shows a spectrogram in the measurement of a large step portion. Since there is a sufficient height difference between individual distances, there are differences in the spectrogram. Thereby, it is always possible to determine the height difference of the step and the thickness of the object to be measured.

[0068] FIG. 13 shows the optical element 11 of the optical device 21. In the present embodiment, the optical element 11 has a pyramid shape.

[0069] FIGS. 14a and 14b show the optical element 11 of the optical device 21, respectively. FIG. 14a shows the lens segments 16 excluding the central region in a plan view. In FIG. 14b, the lens pieces 16 from the edge region of the convex lens are visible in a three-axis view.

[0070] FIGS. 15a, 15b, and 15c each show the arrangement of square lens pieces. In each case, the four squares represent four lens pieces. The colored circular regions in the center of each group indicate the foci within the depth created by the lens. The lens pieces may have various shapes, such as circular or hexagonal.

[0071] FIG. 15a shows an example of the arrangement of four interleaved groups of lens pieces, which allows for infinite interleaving.

[0072] FIG. 15b shows a seamless interleaved arrangement of 16 measurement points, which can be infinitely extended.

[0073] FIG. 15c shows a dense interleaving of five lens groups. However, when expanding the circular aperture shape in this highly efficient manner, losses are inevitable.

[0074] FIGS. 16a and 16b each show an embodiment of an optical device. FIG. 16a is a view related to a microlens array 16 in which the aperture shape is completely divided. FIG. 16b is a view related to a microlens array 16 in which the lens pieces are arranged in an interleaved manner.

[0075] Regarding other embodiments of the distance and / or thickness measuring device according to the present invention, for the sake of avoiding repetition, please refer to the general part of the specification and the appended claims.

[0076] Finally, the embodiments of the device according to the present invention are only useful for explaining the claimed teachings and are not limiting.

Explanation of Reference Numerals

[0077] 1 ··· Common focus chromatic aberration type optical system 2 ··· Optical axis 3 ··· Partial beam of measurement light 4 ··· Partial beam of measurement light 5 ··· Focus 6 ··· Focus 7 ··· Axis of the axial focus group 8 ··· Axis of the measurement point group not in the central part 9 ··· Axis of the measurement point group not in the central part 10 ··· Illumination aperture 11 ··· Optical element 12 ··· Optical element 13 ··· Virtual plane 14 ··· Microlens array 15 ··· Primary light beam 16 ··· Lens piece 17 ··· Lens piece in the adjacent region 18 ··· Microlens array 19 ··· Dark region 20 ··· Light source 21 ··· Optical device 22 ··· Optical coupling element 23 ··· Optical waveguide 24 ··· Object to be measured 25 ··· Spectrometer 26 ··· Evaluation unit 27 ··· Controller 28 ··· Receiving aperture a ··· Spectrogram b ··· Spectrogram c ··· Total spectrogram d ··· Noise level e ··· Peak width

Claims

1. A one-dimensional confocal chromatic aberration type distance and / or thickness measuring device having a confocal chromatic aberration type optical system (1) and an illumination aperture (10), wherein an optical device (21) is disposed between the illumination aperture (10) and the confocal chromatic aberration type optical system (1), the optical device (21) divides the measurement light emitted from the illumination aperture (10) into a plurality of partial beams (3, 4) of the measurement light, and after the plurality of partial beams (3, 4) of the measurement light pass through the confocal chromatic aberration type optical system (1), they hit a measurement object (24) at a plurality of measurement points offset in the lateral direction, and a plurality of partial beams of the detection light reflected from the plurality of measurement points hit a light receiving aperture (28) via the confocal chromatic aberration type optical system (1) and the optical device (21), and after passing through the light receiving aperture (28), they become a single common detection light beam, a distance and / or thickness measuring device.

2. The distance and / or thickness measuring device according to claim 1, wherein the illumination aperture (10) and / or the light receiving aperture (28) is formed by a fiber end of an optical waveguide (23) and / or at least one aperture element.

3. The distance and / or thickness measuring device according to claim 1 or claim 2, wherein the illumination aperture (10) and the light receiving aperture (28) are formed by a common component.

4. The distance and / or thickness measuring device according to any one of claims 1 to 3, wherein the optical device (21) has an optical element (11), in particular, a refractive optical element, a diffractive optical element, and / or a meta-optical element.

5. The distance and / or thickness measuring device according to claim 4, wherein the optical element (11) is a roof prism, a microlens array (14, 18), and / or an optical pyramid, preferably a regular pyramid or a right-angled pyramid.

6. The distance and / or thickness measuring device according to claim 4 or claim 5, wherein the optical element (11) is added with a second optical element (12) such as a converging lens or a diverging lens.

7. The distance and / or thickness measuring device according to claim 5, wherein the second optical element (12) is formed integrally with the optical element (11), or is disposed in a materially bonded state on the optical element (11), or is printed on the optical element (11), or the second optical element (12) is incorporated in the optical plane of the optical element (11).

8. The distance and / or thickness measuring device according to any one of claims 1 to 7, wherein the optical device (21) individually focuses a plurality of partial beams (3, 4) of the measurement light on a virtual plane, particularly a curved surface, located in front of the confocal chromatic aberration optical system (1).

9. The distance and / or thickness measuring device according to claim 8, wherein the virtual plane (13) is located at the focal point of the confocal chromatic aberration optical system (1).

10. The distance and / or thickness measuring device according to any one of claims 1 to 7, wherein the optical device (21) divides the measurement light emitted from the entrance aperture into a plurality of partial beams (3, 4) of the diverging measurement light.

11. The distance and / or thickness measuring device according to any one of claims 1 to 10, wherein the optical device (21) masks the optical elements (11, 12) with an opaque layer containing chromium or lacquer to narrow the partial beam of the measurement light near the axis among the partial beams (3, 4) of the measurement light.

12. The distance and / or thickness measuring device according to any one of claims 1 to 11, wherein the partial beam of the measurement light near the axis among the partial beams (3, 4) of the measurement light can be deflected by the optical device (21) so as not to hit the confocal chromatic aberration optical system (1) and / or so as to hit only the edge region of the confocal chromatic optical system (1).

13. The distance and / or thickness measuring device according to any one of claims 1 to 12, wherein the focusing lens of the optical device (21) has a beam deflection plane within the core region near the axis and / or is blocked by the beam deflection plane.

14. The optical device (21) has optical elements (11, 12) having a plurality of lens pieces (16), A plurality of central lens pieces (17) located in the central region and a plurality of peripheral lens pieces located in the edge region are arranged, The distance and / or thickness measuring device according to any one of claims 1 to 13, characterized in that each of the plurality of central lens pieces (17) deflects the measurement light hitting itself and overlaps it with the measurement light deflected by the edge lens pieces to form a single common partial beam (3, 4) of the measurement light.

15. The distance and / or thickness measuring device according to any one of claims 1 to 14, in particular a one-dimensional, confocal chromatic aberration type distance and / or thickness measuring device having a multi-color light source (20) that emits measurement light, a spectrometer (25), and an evaluation device.

16. A one-dimensional confocal chromatic aberration type distance and / or thickness measuring method having the distance and / or thickness measuring device according to any one of claims 1 to 14 or the distance and / or thickness measuring device according to claim 15, The measurement light from the multi-color light source (20) is guided to the optical device (21) through the illumination aperture (10), The measurement light is split into a plurality of partial beams (3, 4) of the measurement light by the optical device (21) and guided to the confocal chromatic aberration type optical system (1), A plurality of partial beams (3, 4) of the measurement light emitted from the confocal chromatic aberration type optical system (1) hit the measurement object (24) at a plurality of measurement points offset in the lateral direction, A plurality of partial beams of the detection light reflected from the plurality of measurement points hit the light receiving aperture (28) through the confocal chromatic aberration type optical system (1) and the optical device (21). After passing through the light receiving aperture (28), a single common detection light beam is supplied to the spectrometer (25), and a total spectral coded measurement signal at the plurality of measurement points is generated. Distance and / or thickness measuring method.

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