Confocal chromatic beam distance measurement system and method

Abstract

A confocal chromatic beam distance measuring system comprising a line light source (2), an aperture (3), a confocal chromatic measuring lens (6), preferably a rotationally symmetric confocal chromatic measuring lens, and a spectrometer (14), preferably a two-dimensional spectrometer, in which the illumination beam path extends from the line light source (2) to the measurement object (9) via the aperture (3) and a first area (5) of the confocal chromatic measuring lens (6) and the imaging beam path extends from the measurement object (9) to the spectrometer (14) via a second area (11) of the confocal chromatic measuring lens (6). Furthermore, a confocal chromatic beam distance measuring method is also defined.

Description

[Technical field]

[0001] The present invention relates to a confocal chromatic beam distance measurement system that includes a line source, an aperture, a confocal chromatic measurement lens, and a spectrometer.

[0002] Furthermore, the present invention relates to a confocal chromatic light distance measurement method. [Background technology]

[0003] Confocal chromatic point ranging systems and methods have been known in the industry for many years. These systems and methods are characterized by extremely high distance resolution, with measurement spot diameters in the range of a few micrometers (3 μm to 30 μm). This makes it possible to achieve particularly high resolution in the lateral and distance directions during the scanning process, which has a measurement spot diameter that is up to ten times larger than in point triangulation methods. A further advantage of the confocal chromatic distance sensor is that it is less susceptible to speckle compared to laser sources. Furthermore, when measuring the thickness of thin layered objects, significantly higher depth resolution can be achieved and the small sensor size in the area of ​​the object reduces the chance of collision between the sensor and the object.

[0004] Furthermore, confocal chromatic beam distance measurement systems are already known and can be divided into two basic approaches. One is to project a light beam concentrically through a confocal chromatic aberration lens and measure it, and the other is to use the principle of confocal chromatic theta microscopy.

[0005] The former approach has the basic advantage of being compact in design and easy to use due to the spherical shape of the slightly restricted working space around the measurement range. It is also possible for the user to change the lenses.

[0006] The latter approach offers significant improvements in depth (z) and lateral (x) resolution, but is limited by its complex and space-consuming mechanics and the need for complex alignment during sensor fabrication. In one-dimensional confocal chromatic distance measurement, the colored focal array lies on the lens axis, but this principle has severe limitations when projecting and imaging an array of colored light rays in the same plane as the lens axis. This is because in practice, crosstalk always occurs in adjacent channels at nearby measurement positions due to the spread occurring between the illumination focus and the display focus. This is due to the very strong overlap of the corresponding transmit and receive beams, especially in the Z direction.

[0007] Thus, rather than projecting and observing a continuous line, the '163 patent uses a series of discrete measurement points for projection and detection using a fiber array. These individual measurement points are so far apart that the effects of crosstalk between the individual channels are negligible.

[0008] The advantage of confocal chromatic theta microscopy is that the effective aperture is so large that the depth of field of the illumination and observation foci can be significantly reduced without losing too much measurement range in the Z direction. Patent Document 2 discloses that a confocal chromatic irradiation optical system emits multispectral light rays to form a light ray array that is converted into spectral data, and that this light ray array is positioned at an angle theta (Θ) with respect to the optical axis of the lens to form a measurement surface. A second optical system is positioned at a negative angle theta (-Θ) with respect to the measurement plane and images onto an area detector based on the Scheimpflug principle. To evaluate the color code on the sensor representing the measured height, a color gradient filter takes over the function of the spectral aperture. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 10725178(A1) [Patent Document 2] European Patent Application Publication No. 2901102 (A1) Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention is based on the task of designing and further developing a confocal chromatic beam distance measurement system and method that allows synchronous measurements along the entire beam with high depth resolution, low space requirements and high measurement speed. [Means for solving the problem]

[0011] Regarding the system, the above mentioned problem is solved by the features of claim 1. Thus, the confocal chromatic beam distance measurement system is a confocal chromatic beam distance measurement system comprising a line source, an aperture, a confocal chromatic measurement lens, preferably a rotationally symmetric confocal chromatic measurement lens, and a spectrometer, preferably a two-dimensional spectrometer, wherein the illumination beam path extends from the line source to the measurement object via the aperture and a first region of the confocal chromatic measurement lens, and the imaging beam path extends from the measurement object to the spectrometer via a second region of the confocal chromatic measurement lens. The term "rotationally symmetric" also includes embodiments in which the lenses have angular trim, but are arranged or designed to be rotationally symmetric in the broadest sense.

[0012] Regarding the method, the above mentioned problem is solved by claim 20. Therefore, there is provided a confocal chromatic beam distance measurement method using a confocal chromatic beam distance measurement system as described in any one of claims 1 to 19, in which illumination light is directed from a line light source to a measurement object via an aperture and a first area of ​​the confocal chromatic measurement lens as a colored illumination surface, and measurement light converted into spectral data is guided from the measurement object to a spectrometer, preferably a two-dimensional spectrometer, via a second area of ​​the confocal chromatic measurement lens, and a spectral analysis of the measurement light is performed to determine the distance.

[0013] In accordance with the present invention, it is recognized that the underlying problem can be solved by a confocal chromatic hyperspectral light space measurement system that follows the resolution enhancement principles of confocal theta microscopy. For example, a continuous white light beam can be projected onto the measurement object, whose height profile is reflected in the coloring of the Z distance to the measurement lens. Based on the spectroscopic hyperspectral analysis of this measurement line, a synchronous, locally continuous and high distance resolution can be achieved over the entire beam. The corresponding analysis can be carried out in an evaluation unit constructed for this purpose, for example a computer.

[0014] In a system including a line light source, an aperture, a confocal chromatic measurement lens, and a spectrometer, a first region of the measurement lens (e.g., half of the measurement lens) is used to illuminate the measurement point with a spectrally datatable array of light rays, and a different second region of the measurement lens (e.g., the other half of the measurement lens) is used to image a spectrally datatable height profile reflected by the measurement object. This means that the illumination and imaging paths are separated from each other, realizing the confocal chromatic theta microscopy approach with only one measurement lens. Furthermore, the measurement lens serves the functions of both the illumination optics and the imaging optics. The aperture may be designed as a separate element or as part of the line light source. Additionally, the openings may be, for example, slot-like openings.

[0015] As a specific configuration, the line light source may be disposed on the entrance side of the focal point of the confocal chromatic measurement lens. Furthermore, the entrance aperture of the spectrometer may be located at the exit side of the focal point of the confocal chromatic measurement lens. In order to divide the confocal chromatic measurement lens into two regions or two functional half-regions, the confocal chromatic measurement lens may be obstructed, for example, using a directional opening, so that the light is not distributed symmetrically within the confocal chromatic measurement lens, but only in the first region of the measurement lens. Using this configuration of the invention, the measurement light passes through only one side of the measurement objective, and the multispectral light rays coming from only one side of the measurement objective fan out to form a group of curves that can exist as a plane within the optical axis of the measurement objective. If the measurement object is present in this plane, a height profile is created and the distance of this height profile to the measurement lens is reflected by the color that is in focus at this distance. The heightened chromatic profile beam created on the measurement object is reflected by a second region of the confocal chromatic measurement lens to the location of the line source.

[0016] In a further method according to the present invention, since the illumination beam path and the imaging beam path are different paths, the disadvantage that arises with the same optical path, i.e., overlapping of the transmitted and received beams resulting in lateral crosstalk between adjacent measurement positions, is avoided. In this way, signal-degrading "crosstalk" can be avoided without having to resort to the equally disadvantageous solution of an illumination spot array, which requires lateral measurement spacing. As a result, the measuring device according to the present invention allows for high speed two-dimensional continuous light measurement with a large depth of field. Another advantage resides in the spectroscopic evaluation of the colored height profile. In the state of the art, this profile is evaluated in a triangulation manner using spectral filtering, which requires a color gradient filter to be placed in front of the matrix. This filter has the same wavelength curve as the focal plane and acts as a color gradient aperture. This provides a sort of "autofocus." However, if this filter is inaccurate, the focal plane of the first confocal chromatic lens will not exactly coincide with the detection plane, resulting in precision errors. These problems do not occur when using a spectrometer.

[0017] The measured light beam is evaluated by a spectrometer, preferably a two-dimensional spectrometer, which is spectrally decomposed on a matrix so that the colored height profile is evaluated only after spectral decomposition, for example by a CMOS area detector. The inherent insensitive areas of the sensor between the individual pixels can be supplemented, for example, by a microlens array. That is, it is the spectrometer matrix that influences the quantization noise since the signal is passed to the matrix in analog form.

[0018] Furthermore, it has been recognised that a concentric lens arrangement for the measurement lens has the advantage that it is much easier to manufacture. Furthermore, this type of measurement lens has the advantage that its form factor provides more free space around the lens. A further advantage is that by simply changing the measurement lens it is possible to change the measurement range and therefore also the resolution of the measurement system. This is because the measurement lens creates a measurement plane from the multispectral lines and combines this measurement plane into a colored light beam. The position and scale of the image relative to the line source is independent of the measurement lens. Therefore, the width and height of the measurement plane projected by the measurement lens, and therefore the resolution, is independent of the rest of the measurement system. Furthermore, the system according to the invention is extremely compact, since it makes it possible to omit both the cross-measurement lens arrangement and the multi-fiber arrangement required in known systems. Even though the diameter of the measurement lens can be made smaller in a crossed measurement lens arrangement to achieve the same depth resolution, it is necessary to have a similar measurement lens diameter as the system of the present invention to achieve comparable slope characteristics. The inclination characteristic here refers to the angle at which the surface normal of the measurement object can be positioned relative to the axis of the measurement system, and means that the signal-to-noise ratio of the measurement light is sufficiently good. This quality criterion is important when measuring curved surfaces.

[0019] It is advantageous if the confocal chromatic measuring lens, the entrance aperture of the spectrometer and possibly other parts of the system (transformation optics) are arranged on a common virtual (imaginary) optical axis.

[0020] Advantageously, the confocal chromatic measuring lens comprises only one lens. The lens may be a field correcting lens, for example a pressed double spherical lens, or a double aspheric lens. Alternatively, it is also conceivable that the confocal chromatic measurement lens comprises at least two optical lenses. The lenses may be arranged concentrically with respect to one another. This results in a particularly simple design of the measuring lens and the characteristic small installation space.

[0021] Advantageously, a single confocal chromatic measuring lens is arranged. The use of only a single measurement lens, whose measurement surface is also located on the optical axis, has the advantage, compared to systems with several measurement lenses, that the free space around the measurement point is very large and at the same time spherical. This means that the confocal chromatic beam distance measuring system can be flexibly used for automatic measurements. This principle also makes it possible to arrange the measurement lens inside the hole, which significantly increases the range of application of the system compared to systems with, for example, several measurement lenses. Furthermore, a design with only a single measurement lens has the advantage that thermal effects are reflected in both the illumination light and the measurement light. Due to the symmetrical design, thermal effects on the measurement system are more uniform than in arrangements with multiple measurement lenses and therefore easier to compensate. In the case of a multiple measurement lens arrangement, the illumination and measurement surfaces may be far apart, making them susceptible to thermal changes. Another advantage of using a single measurement lens compared to a multiple measurement lens arrangement is that focal length tolerances become irrelevant. Manufacturing and alignment tolerances of the measurement lenses directly translate into poor quality when using two measurement lenses, because the illumination surface of the first measurement lens is not exactly positioned directly above the measurement surface captured by the second measurement lens. It is also difficult to keep their spectral focus positions together over the entire distance range.

[0022] Compared to a system with two separate measurement lenses that cross each other and have limited proximity, a particularly high lateral resolution can be achieved at high light intensities by using a single measurement lens with a very narrow measurement range.

[0023] It is further advantageous if the optical axis of the confocal chromatic measuring lens coincides with the distance axis of the system. This has the advantage that almost no installation space is required for the system, and the measurement surface can be placed in a position that is easy for the user to understand.

[0024] It is further advantageous if the line light source emits a continuous white light beam. The separate illumination and imaging paths of the present invention allow the use of a continuous line light source. This is not possible with the same optical path because the transmit and receive beams would overlap as discussed above. By using a continuous white light beam, high lateral and depth resolution can be achieved.

[0025] It is particularly advantageous if the line source emits two or more, preferably consecutive, radiation beams. Furthermore, two or more line light sources may be arranged, and each line light source may emit at least one, preferably continuous, radiation line as the radiation light. In this configuration, two or more parallel beams are projected and evaluated. In one embodiment, illumination for the various radiation lines may be generated by a common light source and emitted simultaneously from multiple apertures, emitted from separate light sources that can be individually controlled, or emitted from a common light source with multiple apertures that can be individually blocked. The aperture of the light source is located near the virtual optical axis, where the degree of proximity may be defined as, for example, half the distance of the profile length from the virtual optical axis, if desired. As described in the following embodiments, a single spectrometer, preferably a two-dimensional spectrometer, for example a Dyson spectrometer, may be deployed. The spectrometer entrance aperture may have as many entrance apertures as there are illumination lines. The position and distance of the entrance aperture may correspond to the position and distance of the light source, but must take into account any scaling caused by the transformation optics.

[0026] It is advantageous if the line light source is arranged on the entrance side of the focal point of the confocal chromatic measuring lens, which simplifies the beam path and enables accurate acquisition of the measured values.

[0027] It is further advantageous if a deflection element is arranged in the illumination beam path and / or in the imaging beam path. In the device according to the invention, the deflection element can deflect the illumination light and / or the measurement light, since the line light source and the imaging are at the same spatial position. The deflection element may always be arranged in the illumination path or in the imaging path. In particular, it is conceivable to arrange a deflection element between an aperture in the illumination beam path and the confocal chromatic measurement lens, and / or to arrange a deflection element between the confocal chromatic measurement lens and the spectrometer in the imaging beam path. The arrangement of deflection elements in both the illumination beam path and the imaging beam path allows for a particularly compact design. It is also conceivable that the deflection element acts as a directional aperture and blocks the illuminating light so that it only hits the confocal chromatic measuring lens in a first region. The directional aperture may be realized as a separate element from the deflection element. An optical element in the beam path defines a fixed area over which the light is emitted, and therefore also the area illuminated by the chromatic optics.

[0028] It is particularly advantageous if the deflection element is designed as a mirror or a beam splitter. The advantage of the mirror is that the energy loss remains within the range of 0% to 3%. The use of a beam splitter could be considered, but this would result in an energy loss of at least 75%.

[0029] It is further advantageous if the design includes a transformation optics arrangement. To achieve a sufficient amount of light, the line source may be relatively large in extent, but at the same time, the technically and economically efficient area scan camera is quite small. This imbalance can be compensated for by transformation optics. In principle, the transformation optics adjusts the length of the aperture or illumination slit to the length of the entrance aperture of the spectrometer. It is advantageous if the conversion optics is arranged between the confocal chromatic measuring lens and the spectrometer. Because this is where you can get the most benefit with the least amount of effort. Another possible location for the transformation optics is between the light source and the confocal chromatic measurement lens, where the illumination enters the lens at a reduced size. In other words, the transformation optics is a transformation element for matching technically available elements to a line light source and a spectrometer.

[0030] It is advantageous if the transformation optical system has at least one optical lens, which in the basic optical model is arranged concentrically with the confocal chromatic measuring lens or is located on a common virtual (imaginary) optical axis together with the confocal chromatic measuring lens and possibly other elements (aperture, entrance slit of the spectrometer). The concentric arrangement allows for an optimized optical design for all field points, even in the absence of an ideal parallel beam section.

[0031] The spectrometer or 2D spectrometer may be a Dyson spectrometer. To increase the measurement speed, it is essential to provide sufficient photons to the detector elements. For a signal to pass through the chain, the detector must have high quantum efficiency. The choice of a Dyson spectrometer for the analysis of the reflected measurement light has the added advantage that the evaluation area detector is illuminated almost perpendicularly and the illumination angle is not large (as is required for triangulation methods according to the Scheimpflug principle). This ensures the highest possible quantum efficiency for this critical element, which has a positive effect on the overall signal processing. Dyson spectrometers allow for a large entrance NA (numerical aperture), which is linked to the observation NA of the measurement object via the imaging scale. When the inclination angle of the measurement object is large, it is necessary to increase this numerical aperture as much as possible. In particular, the spectrometer may have an entrance aperture (particularly a slit-shaped), an optical lens (particularly a Dyson lens), a diffraction grating (particularly a concave one) and an area detector; such a design is characterized by a simple structure and high measurement accuracy.

[0032] It is further advantageous if the diffraction grating is a blazed diffraction grating and / or has equally spaced parallel structures. Blazed gratings have the advantage of increasing efficiency in the diffraction orders used. Additionally, the width of the entrance aperture may be less than 20 μm, preferably less than 10 μm. This has the advantage that an ideal spectral resolution is achieved for the pixel resolution of the area detector.

[0033] It is particularly advantageous if the illumination beam path and the imaging beam path between the confocal chromatic measuring lens and the measurement object each extend at an angle of 30° to 160°, in particular 60° to 120°, preferably 85° to 95°, ideally 90°. This has the advantage that the highest possible spatial resolution is achieved. By mounting the measurement surface sideways, a much higher depth resolution can be achieved than with concentric object illumination where the illumination and imaging paths are not separated. This is because the effective numerical aperture (NA) is very high. Depth resolution, ie, the distinction between two closely spaced points or planes in the Z direction, is also significantly improved. When the angle between the measurement beam path and the imaging beam path is 90°, imaging is ideal, and the smaller the angle, the more the effect of shadowing on the step can be reduced.

[0034] Furthermore, it should be noted that the above-described features of the confocal chromatic beam distance measurement system according to the invention also have embodiments in the sense of procedures. Combinations of these features with the relevant features of the method claims are not only possible but also advantageous.

[0035] There are various possibilities for advantageously designing and further developing the method of the invention. Reference is made on the one hand to the claims following claim 1 and on the other hand to the following description of embodiments of the invention with reference to the drawings, in which: In connection with the description of embodiments of the invention with reference to the drawings, general and further embodiments of the method of the invention are also described. [Brief description of the drawings]

[0036] [Figure 1] 1 is a schematic diagram of an embodiment of a confocal chromatic beam distance measurement system according to the present invention, and a method according to the present invention can also be described. [Diagram 2] FIG. 2 is a three-dimensional schematic diagram of the embodiment of FIG. 1. [Diagram 3] 3 is a schematic diagram of a further embodiment of a confocal chromatic beam distance measurement system according to the invention, and also allows for the description of a method according to the invention; [Figure 4] FIG. 2 is a schematic diagram of the theoretical beam model underlying the method according to the invention; [Diagram 5] 3 is a schematic diagram of a further embodiment of a confocal chromatic beam distance measurement system according to the invention, and also allows for the description of a method according to the invention; [Figure 6] The ray position m is plotted over the measurement distance z for three different measurement planes. [Figure 7] 1 is an example of a profile of a measurement object imaged by an area detector, recorded based on the measurement surface. [Figure 8] FIG. 2 is an exemplary diagram of three spectral ranges, where area detector line m is plotted over area detector column n. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] 1 and 2 show a first embodiment of a confocal chromatic beam distance measurement system according to the present invention. In this confocal chromatic beam distance measurement system, a white light illumination beam 1 is emitted from a line source 2 having an aperture 3, such as a slit aperture. The illuminating light 1 is directed by a deflection element 4 onto a first region 5 of a confocal chromatic measuring lens 6 . In this embodiment, the confocal chromatic measuring lens 6 comprises two optical lenses 7, 8 arranged concentrically with respect to one another. Illumination light 1 is irradiated onto a measurement object 9 through a confocal chromatic measurement lens 6 . From this it becomes clear that the illumination beam path defined by the illumination light 1 passes only through the first region 5 of the confocal chromatic measuring lens 6 .

[0038] The measurement light 10 reflected by the measurement object 9 and having a height profile for each wavelength passes only through the second region 11 of the confocal chromatic measurement lens 6 . Transformation optics 12 are used to shorten the length of the measurement light 10 to the length of the entrance aperture 13 of a spectrometer 14 . Distance measurement is performed by hyperspectral analysis of this measurement line. The imaging beam path defined by the measuring light 10 is therefore separate from the illumination beam path of the method according to the invention. The deflection element 4 then also functions as a directional aperture 18, ensuring that only the first area 5 of the confocal chromatic measuring lens 6 is illuminated and that stray light does not affect the second area 11.

[0039] Furthermore, FIG. 2 shows a measurement plane 28 on which the focal points of the different wavelengths 29, 30, 31 of the measurement light 10 are located.

[0040] FIG. 3 shows a further embodiment of a confocal chromatic beam distance measurement system according to the invention. The system comprises a line light source 2 and an aperture 3 which is used to create a band of light in the X-direction. Half of the aperture of the illuminating light 1 is directed via a deflecting element 4 in the form of a mirror only onto a first area 5 of a confocal chromatic measuring lens 6, and after passing through the first area 5 the illuminating light 1 reaches the measurement object 9. The confocal chromatic measuring lens 6 includes two concentrically arranged aspheric lenses 15, 16 which function as both illumination optics and imaging optics. However, these do not necessarily have to be aspheric lenses, and other useful types of lenses can also be arranged.

[0041] The measuring light 10 reflected by the measuring object 9 passes only through a second region 11 of the confocal chromatic measuring lens 6 and is supplied to the transformation optics 12 by means of a further deflecting element 17 designed as a mirror. The transformation optics 12 comprises two optical lenses 19 , 20 and provides a sized image onto a slit-shaped entrance aperture 13 of the spectrometer 14 , which is different from the aperture 3 . In this embodiment, the spectrometer 14 is designed as a two-dimensional Dyson spectrometer and comprises, in addition to the entrance aperture 13, a Dyson lens 23 and a concave diffraction grating 24. Spectrometer 14 may have configurations other than that shown. Thus, in this embodiment the illumination beam path and the imaging beam path are separated from each other and a single confocal chromatic measurement lens 6 is provided. Furthermore, in this embodiment, as in the embodiment of FIGS. 1 and 2, the optical axis 26 of the confocal chromatic measuring lens 6 coincides with the distance axis 27 . Furthermore, Figures 1 to 3 clearly show that the aperture 3, the confocal chromatic measuring lens 6, the transformation optics 12 and the entrance aperture 13 lie on a common virtual (imaginary) optical axis 26a.

[0042] Although the above described embodiments show a confocal chromatic measurement lens 6 having two lenses 15, 16 each, this configuration is not necessary. The confocal chromatic measurement lens 6 may have only one lens or two or more lenses.

[0043] FIG. 4 shows a schematic diagram of the theoretical beam model on which the method according to the invention is based. From this figure it can be clearly seen that the line source 2 and the entrance aperture 13 of the spectrometer 14 are at exactly the same spatial position and lie on a common imaginary optical axis 26a.

[0044] FIG. 5 shows one embodiment of a confocal chromatic beam distance measurement system according to the present invention, which corresponds to the confocal chromatic beam distance measurement system shown in FIG. The main difference is that three separate line light sources (2, 2a, 2b) are arranged with their own apertures (3, 3a, 3b). The illumination may be generated by a single light source having multiple apertures (eg, multiple slit apertures) or by separate light projectors.

[0045] There are three adjacent measurement planes (28, 28a, 28b) due to the offset of the line light sources (2, 2a, 2b), preferably in a parallel manner. Furthermore, the spectrometer (14) has a number of slit openings (13) corresponding to the number of exit openings (3, 3a, 3b) or the number of radiation lines. Furthermore, please refer to the description of the previous embodiment, which also applies to the confocal chromatic beam distance measurement system shown in FIG.

[0046] FIG. 6 shows, for each measurement plane (28, 28a, 28b), the assignment (32, 32a, 32b) of the measurement distance (z) to the position m of the ray on the matrix. However, the expression is simplified here, and the measurement positions are shown as individual measurement positions in the x-axis direction and shifted only in the z-axis direction. To fully map this assignment, the x-axis direction must be taken into account.

[0047] FIG. 7 shows the profile of the measurement object (9) imaged on the area detector (22) and recorded on the basis of three measurement planes (28, 28a, 28b).

[0048] Furthermore, FIG. 8 shows three spectral ranges (34, 34a, 34b) for which the measurement signal of the associated measurement plane is discrete in y-position. It can be seen that the spectra of adjacent entrance apertures 13 are imaged onto different areas of the area detector (22) due to different angles of incidence on the grating. Clearly, the overlap of the resulting spectral ranges (34, 34a, 34b) can cause problems with assignment, as the monochrome area detector (22) loses color information necessary to make the assignment unambiguous.

[0049] However, using a multicolor or hyperspectral area detector (22) rather than a monochromatic detector allows differentiation.

[0050] When the spectral image of each entrance aperture 13 is viewed across the spectrum (see FIG. 8), due to the different angles of incidence on the diffraction grating 24, each entrance aperture 13 produces a separate spectral image in the spectrometer (14). Furthermore, since these spectral ranges overlap significantly, it is desirable to satisfy the following boundary conditions for evaluation: 1. By using a polychromatic or hyperspectral area detector (22) in the spectrometer (14), a corresponding entrance aperture 13, i.e., the measurement plane (y-position) at any measurement point, is defined on the detector based on the incident wavelength. With this information, a calibration table corresponding to the measurement surface can be used. 2. Properly control the illumination to project illumination at different display levels over time. In this way, based on the selected light source, a corresponding calibration table can be used for evaluation. 3. With a monochromatic sensor, clearly distinguishable measurement profiles are expected to remain in their respective regions, so that the spatial ranking along the m-axis remains constant during the measurement task. To achieve this, it is necessary to ensure that the images of the two profiles on the detector do not overlap.

[0051] As regards further advantageous embodiments of the device according to the invention and the method according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetition.

[0052] Finally, the above-described embodiments of the device according to the invention and the method according to the invention are intended to illustrate the claimed method and are not intended to be limiting to these embodiments. [Explanation of symbols]

[0053] 1. Irradiation light 2, 2a, 2b...Line light source 3, 3a, 3b...opening 4...Deflection element 5. First area (measuring lens) 6. Confocal chromatic measuring lens 7 Optical Lenses 8. Optical Lenses 9. Measurement object 10. Measurement light 11 Second area (measuring lens) 12 Transformation optics 13, 13a, 13b...Incidence aperture 14...Spectrometer 15 Lens 16 Lenses 17...deflection element 18...Directional opening 19 Optical Lenses 20 Optical Lenses twenty one 22 Area Detector 23 Dyson Lens 24... Diffraction grating twenty five 26 Optical axis (measuring lens) 26a Virtual optical axis 27...distance axis 28, 28a, 28b...Measurement surface 29...Wavelength 1 30...Wavelength 2 31...Wavelength 3 32, 32a, 32b ···m = f(z,x,y), where x, y = constants. 33, 33a, 33b... Coloring profile 34, 34a, 34b...Spectral range m Light area detector n column region detector x: position along the ray y: The horizontal position of the projection plane z: Distance measurement point from the measurement lens

Claims

1. A confocal chromatic beam distance measurement system comprising a line light source (2), an aperture (3), a confocal chromatic measurement lens (6), preferably a rotationally symmetric confocal chromatic measurement lens, and a spectrometer (14), preferably a two-dimensional spectrometer, the illumination beam path extends from the line light source (2) to the measurement object (9) via the aperture (3) and a first region (5) of the confocal chromatic measurement lens (6); A confocal chromatic optical distance measurement system, wherein the imaging beam path extends from the measurement object (9) to the spectrometer (14) via a second region (11) of the confocal chromatic measurement lens (6).

2. 2. The confocal chromatic beam distance measurement system of claim 1, characterized in that the aperture (3), the confocal chromatic measurement lens (6) and the entrance aperture (13) of the spectrometer (14) are on a common virtual optical axis (26a).

3. the confocal chromatic measuring lens (6) has only one optical lens or the confocal chromatic measuring lens (6) has at least two optical lenses (7, 8), 3. A confocal chromatic beam distance measuring system according to claim 1 or 2, characterized in that the optical lenses (7, 8) of the confocal chromatic measuring lens (6) are arranged concentrically with respect to one another.

4. 4. A confocal chromatic beam distance measuring system according to claim 1, characterized in that a single confocal chromatic measuring lens (6) is arranged.

5. A confocal chromatic beam distance measuring system according to any one of claims 1 to 4, characterized in that the optical axis (26) of the confocal chromatic measuring lens (6) coincides with a distance axis (27) of the confocal chromatic beam distance measuring system.

6. A confocal chromatic beam distance measuring system according to any one of claims 1 to 5, characterized in that the line light source (2) emits a continuous white light beam.

7. A confocal chromatic beam distance measuring system according to any one of claims 1 to 6, characterized in that the line light source (2) emits two or more, preferably consecutive, radiation lines as radiation light, and / or that a plurality of line light sources (2) are arranged such that each of the line light sources (2) emits at least one, preferably consecutive, radiation line as radiation light.

8. 8. The confocal chromatic light distance measuring system according to claim 1, wherein the line light source (2) is arranged on the incident side of the focal point of the confocal chromatic measuring lens (6).

9. a deflection element (4) is arranged in the illumination beam path and / or in the imaging beam path, A confocal chromatic beam distance measurement system as claimed in any one of claims 1 to 8, characterized in that the deflection element (4) acts as a directional aperture (18) to block the illuminating light (1) so that the illuminating light (1) hits the confocal chromatic measurement lens (6) only in the first region (5).

10. 10. The confocal chromatic light distance measuring system according to claim 9, characterized in that the deflection element (4) is designed as a mirror or a beam splitter.

11. 11. The confocal chromatic optical distance measuring system according to claim 9 or 10, characterized in that a deflection element (4) is arranged in the illumination beam path between the aperture (3) and the confocal chromatic measuring lens (6) and / or a deflection element (4) is arranged in the imaging beam path between the confocal chromatic measuring lens (6) and the spectrometer (14).

12. 12. A confocal chromatic beam distance measuring system according to any one of claims 1 to 11, characterized in that a transformation optics (12) is arranged.

13. 13. The confocal chromatic beam distance measuring system according to claim 12, characterized in that the transformation optical system (12) is arranged in the imaging beam path between the confocal chromatic measuring lens (6) and the spectrometer (14), or in the illumination beam path between the line light source (2) and the confocal chromatic measuring lens (6).

14. The transformation optical system (12) has at least one optical lens (19, 20), A confocal chromatic beam distance measuring system as described in claim 12 or claim 13, characterized in that the at least one optical lens (19, 20) is arranged concentrically with the confocal chromatic measuring lens (6) in the basic optical model and / or is located on the common virtual optical axis (26a) together with the confocal chromatic measuring lens (6).

15. A confocal chromatic beam distance measuring system according to any one of the preceding claims, characterised in that the spectrometer (14) is a Dyson spectrometer.

16. A confocal chromatic beam distance measuring system according to any one of claims 1 to 15, characterized in that the spectrometer (14) comprises an entrance aperture (13), in particular a slit-shaped, an optical lens (23), in particular a Dyson lens, a diffraction grating (24), in particular a concave, and an area detector (22).

17. 17. The confocal chromatic beam distance measurement system of claim 16, wherein the diffraction grating (24) is a blazed diffraction grating and / or has equally spaced parallel structures.

18. A confocal chromatic beam distance measuring system according to claim 16 or 17, characterized in that the width of the entrance aperture (13) is less than or equal to 20 μm, preferably less than or equal to 10 μm.

19. A confocal chromatic optical distance measuring system as claimed in any one of claims 1 to 18, characterized in that the illumination beam path and the imaging beam path between the confocal chromatic measuring lens (6) and the measuring object (9), respectively, extend at an angle in the range of 45° to 90°, in particular 60° to 90°, preferably 80° to 90° relative to each other.

20. A confocal chromatic beam distance measurement method using a confocal chromatic beam distance measurement system according to any one of claims 1 to 19, comprising the steps of: Illumination light (1) is directed from a line light source (2) to a measurement object (9) via an aperture (3) and a first area (5) of a confocal chromatic measurement lens (6) as a colored illumination surface, The measurement light (10) converted into spectral data is guided from the measurement object (9) to a spectrometer (14), preferably a two-dimensional spectrometer, via a second region (11) of the confocal chromatic measurement lens (6); A confocal chromatic light distance measurement method, wherein a spectroscopic analysis of the measurement light (10) is performed to determine the distance.

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