Device and method for detecting an object surface using electromagnetic radiation

Abstract

Device (10) for detecting an object surface (16), comprising: a radiation generating device (17) with at least one radiation source (12), wherein the radiation generating device (17) is configured to emit first electromagnetic radiation with a first wavelength and second electromagnetic radiation with a second wavelength onto a linear measuring field on an object surface (16) with at least one measuring point (32) of the object surface (16) to be measured or an area of ​​the object surface (16) to be measured, which has at least one measuring point (32) to be measured, wherein the radiation generating device (17) is configured to emit no radiation or radiation used for surface detection onto the measuring point (32) to be measured or onto the area of ​​the object surface (16) in a wavelength range between the first wavelength and the second wavelength.such that the first and second wavelengths are different from each other; and a detection device (31) configured to detect at least one first measurement value and at least one second measurement value for each of the measurement points (32) to be measured, wherein the first measurement value is based on radiation with the first wavelength reflected from the object surface (16) and the second measurement value is based on radiation with the second wavelength reflected from the object surface (16), characterized in that the first and second measurement values ​​are each distance values ​​to the object surface (16) and are determined by triangulation, wherein the detection device (31) comprises an optical separating element (36) to divide the radiation reflected from the object surface (16) into a first and a second radiation component (40, 44), wherein the detection device (31) comprises a photosensitive unit (34),wherein the radiation components (40, 44) separated by means of the optical separating element (36) strike the photosensitive unit (34) at offset points of impact (42, 46), wherein the optical separating element (36) is a dispersion prism or an objective of the detection device (31) serves as the optical separating element (36).

Description

The invention relates to a device and a method for detecting an object surface using electromagnetic radiation. In particular, the invention relates to detecting an object surface for determining distance information, for example by means of at least one laser scanner, preferably a laser line scanner, which emits electromagnetic radiation with different wavelengths. It is known to capture object surfaces, for example those of industrially manufactured workpieces, using optical sensors (i.e., without contact). This allows data to be acquired for measuring and / or mapping the object surface. The measurement typically involves measuring the object surface in its depth dimension (for example, a so-called Z-dimension) and / or, more generally, determining three-dimensional properties of the object surface. In particular, the measurement can provide information about the distance between the object and the optical sensor, and the acquired measurements can be compiled into so-called 3D point clouds. As a result, the three-dimensional properties of an object surface, such as its shape, can be determined.In particular, the measured values ​​can be used to determine dimensions and geometric sizes (such as diameter or width), to compare and evaluate the results with specifications, to calculate properties of the object (for example, quality parameters) and / or to create a three-dimensional graphic representation of the object. Optical sensors are used to measure the surface of an object. One type of optical sensor is the laser sensor, which emits laser radiation and directs it onto the object's surface, as well as detecting the portion of radiation reflected from the surface. The emitted radiation is typically moved relative to and along the object's surface to scan it without contact. Devices with such a laser sensor are also called laser scanners. The relative movement between the radiation and the object can be achieved by moving the laser sensor, which can be done automatically, with machine assistance, and / or by manually moving a handheld laser sensor. Additionally or alternatively, movable optics can be used, for example, by means of movable mirrors, to guide the radiation along the object's surface. Laser sensors or laser scanners emit electromagnetic radiation in the form of laser radiation, typically with only a single defined wavelength or a single defined wavelength range. On the object's surface, the incident radiation forms a measurement area, which can be, for example, point-like or line-like. This measurement area usually contains several measurement points located on the object's surface, for each of which a measurement value is to be determined. The incident laser radiation is reflected from the object's surface (or from the measurement points) and detected by a suitable detection element of the sensor (e.g., a camera). In a known manner, a distance (or Z-value) between the scanning device and the object surface can then be determined as distance information: This can be done using triangulation principles. Knowing, for example, the position of the laser scanner, the current position of any movable optics, and / or the position of a currently measured point on the object surface (for example, in the horizontal or XY spatial plane), the complete 3D coordinates of the measured point on the object surface can also be determined. The information obtained for an object surface in this way can be compiled into a 3D dataset or a 3D point cloud, as previously mentioned. Furthermore, depth information of the object surface can also be determined based on the distance information, for example, in an object coordinate system.Depth information can be said to exist in particular when the object surface extends, as usual, perpendicular to the direction of propagation of the radiation that strikes the object surface and is reflected from the object surface. An example of creating a three-dimensional model of an environment using laser scanning can be found in DE 10 2015 214 857 A1. In this case, too, a discrete set of measured values ​​for sampling points (or measurement points) is generated – which is referred to as a point cloud. The coordinates of the measured points are determined from the angles and the distance relative to an origin, where the location of the laser scanner can be considered the origin. However, with the solutions currently available on the market, sufficient accuracy of the measurement results cannot always be achieved. This is primarily because the object surfaces to be measured can vary considerably with regard to their measurement-relevant properties. Such properties include, for example, the reflectance of the incident radiation, especially when the object surface comprises different materials (e.g., a chrome trim on a plastic substrate). Other relevant properties are the shape and color of the object surface, as well as the presence of areas of varying lightness and / or darkness. It has been shown that the potential diversity of object surfaces to be measured cannot be captured with sufficient accuracy using the solutions available to date. US 2005 / 0088529 A1 discloses an optical surface detection method by illuminating a plurality of structured light patterns corresponding to rainbow-like frequency spectra. US 2015 / 0103358 A1 discloses an optical surface detection method in which several overlapping light patterns are emitted and reflections thereof are detected. US 2012 / 0229606 A1 discloses the illumination of two-dimensional images with at least one wavelength band and varying intensities for surface detection. DE 10 2005 014 525 A1 discloses, for object surface detection, the illumination of a combination of at least two wavelengths in the near-infrared range to achieve immunity to interference from ambient light. US 6 094 270 A discloses a surface detection method using a swivel mirror and assigning detected reflection signals to a current angle of the swivel mirror.Finally, EP 0 076 866 B1 offers an interpolating light sectioning method using strip light patterns. One object of the present invention is therefore to improve the quality of the measurement results in three-dimensional measurement of object surfaces. This problem is solved by a device and a method according to the attached independent claims. Advantageous embodiments are specified in the dependent claims. Furthermore, it is understood that the features mentioned in the introductory description may also be provided individually or in any combination in the solution disclosed herein, unless otherwise specified or apparent. In general, the invention provides for the emission of electromagnetic radiation with at least two different wavelengths to measure an object's surface and for the generation of separate measured values ​​based on the different reflected radiations or radiation components with each of these wavelengths. Each of the reflected radiations at one of the different wavelengths contributes to at least one of the measured values. This does not preclude the possibility that at least one of the measured values ​​is not solely due to radiation at one of the different wavelengths. Rather, at least one of the measured values ​​may correspond to the reflected radiations detected by a sensing device within a specific wavelength range. Conversely, it is possible that at least one of the measured values ​​is determined solely by radiation of a single wavelength emitted by a radiation-generating device and reflected from the object's surface.This is particularly true when the radiation of this wavelength is generated by a laser. Scattered radiation and ambient radiation can further influence the measured value in an undesirable way. Therefore, when electromagnetic radiation with a single wavelength is mentioned below, this implies the possibility that the electromagnetic radiation, especially within the limitations of its generation (e.g., using laser diodes), may only have a single wavelength, or that the electromagnetic radiation exhibits a distribution within a specific wavelength range. In any case, at least two electromagnetic radiations are generated and directed onto the object surface, and at least one measurement is generated for the reflected radiation of each of the (incident) radiations. The use of different wavelengths and the determination of associated separate measured values ​​has the advantage that, if disturbances or inaccuracies occur in the reflected radiation with a certain wavelength, an additional or alternative measured value can be used that was generated based on the reflected radiation with a different wavelength. In detail, the invention proposes a device for detecting an object surface. The device comprises a radiation generating unit with at least one radiation source, wherein the radiation generating unit is configured to emit a first electromagnetic radiation with a first wavelength and a second electromagnetic radiation with a second wavelength at least onto one (preferably several) measuring point of an object surface or onto a measuring area of ​​an object surface that has at least one measuring point, wherein the radiation generating unit is configured to emit a first electromagnetic radiation with a first wavelength and a second electromagnetic radiation with a second wavelength.The wavelength range between the first and second wavelengths does not emit any radiation or radiation used for surface detection onto the measurement point or onto the area of ​​the object surface to be measured, such that the first and second wavelengths are different from each other; and a detection device that is configured to detect at least one first measurement and at least one second measurement for the measurement point or each of the measurement points (i.e., a plurality of first and / or second measurements can also be detected), wherein the first measurement is based on radiation with the first wavelength reflected from the object surface and the second measurement is based on radiation with the second wavelength reflected from the object surface. One advantage of this solution is that at least two measurements are available for each measuring point. One of these measurements can then be selected, or a total measurement can be calculated based on all available measurements. In particular, the selected measurement can be the one that leads to the most accurate or most accurate result of all measurements recorded for that measuring point and / or that has the lowest or lowest measurement uncertainty of all measurements recorded for that measuring point. For example, the occurrence of radiation interference, e.g., in the form of speckle phenomena, depends on the selected wavelength of the emitted radiation. Speckle phenomena appear as spots (speckles) with varying radiation intensity on the irradiated area of ​​the object's surface. They can be attributed to interference caused by the emitted radiation interacting with the optics of the radiation-generating device. For instance, surfaces of optical elements can scatter the generated radiation due to unavoidable roughness resulting from manufacturing processes, thus causing interference even within the radiation-generating device itself. This scattering can depend particularly on the wavelength. The intensity (or...The radiation flux density (or radiant flux density) of the radiation that ultimately reaches the sensor's detection device can therefore fluctuate, even though radiation with a constant intensity was initially generated. In other words, radiation emitted at a specific intensity can be attenuated and / or amplified within the optics due to the interference described, and this attenuation and / or amplification can vary temporally, spatially, and across the entire irradiated area of ​​the object. From the perspective of the detection device, therefore, despite a consistent measurement setup and constant radiation generation, only an unstable signal is received, which can manifest in the captured images, for example, as spatially and temporally varying intensity fluctuations. Such intensity fluctuations can negatively affect the accuracy of the measurement results. By irradiating the device with radiation of at least two wavelengths according to the invention, the probability is increased that the reflected radiation of at least one of the wavelengths, and therefore at least one of the measured values ​​generated therefrom, is distorted to a lesser extent by speckle or other wavelength-dependent errors compared to the other measured value. In a further development, the influence of such wavelength-dependent error sources can be reduced by calculating an average value from the measured values ​​acquired by the detection device for the measurement point(s). A further advantage of using radiation of different wavelengths arises when, as is often the case, the reflectance of the radiation incident on the object's surface is wavelength-dependent. The reflected radiation detected by the sensor can therefore have different (i.e., wavelength-specific) intensities, even if the radiation incident on the respective surface area has the same spectral intensity at the first and second wavelengths. If one of the reflected radiation components (e.g., attributable to radiation with the first wavelength) has an intensity that, for example, leads to the sensor reaching its saturation point at a given exposure time (i.e.,(If the surface has a particularly high reflectance for the wavelength of this radiation component), one can, for example, use the measurement value that is based on radiation with a different wavelength. The term "radiation fraction" initially expresses the fact that not all incident radiation is reflected from the object surface towards the detection device due to scattering effects. Furthermore, the reflected radiation contains all of the incident wavelengths or wavelength ranges. Therefore, to determine the measured values, preferably only a fraction of the total reflected radiation is evaluated, with this fraction having a specific wavelength (or wavelength range). The electromagnetic radiation can be laser radiation with the corresponding first or second wavelengths. The radiation-generating device can comprise an individual beam source (e.g., in the form of a laser source such as a laser diode) for each emitted radiation or wavelength (i.e., a first beam source for the first radiation and a second beam source for the second radiation). More generally, with the exception that the radiation is generated with a single wavelength, but not exactly coherent radiation (as in the case of laser diodes, for example), and therefore a corresponding spectral line broadening occurs, one can speak of a single beam source that generates electromagnetic radiation of a single wavelength. In principle, it can be provided that the incident first and second electromagnetic radiation are emitted with the first and second wavelengths, respectively.The second wavelength contains exclusively the corresponding wavelength. In particular, the first and second radiation can be monochromatic (i.e., containing only the respective first and second wavelengths) and / or coherent, at least within a measurement range of the device. In general, wavelength ranges generated by the radiation-generating device can thus comprise only a single wavelength in the case of monochromatic radiation. The radiation-generating device can comprise at least one beam source (for example, a laser diode) and beam-shaping optics (preferably for each emitted wavelength). However, it is also possible for the radiation-generating device to have only one beam source that emits a wavelength range from which a corresponding first and second radiation are then optically separated. A laser diode (or diode laser) is particularly suitable as the beam source. This can be stabilized and / or include an external resonator. The coherence length of the laser diode can be several centimeters or at least 1 meter. In the context of the present invention, it is possible to emit further electromagnetic radiation with individual (i.e., different) wavelengths or wavelength ranges, for example, a third and fourth electromagnetic radiation with a third and fourth wavelength, respectively. For each of the emitted wavelengths (i.e., for example, for each of the first through fourth wavelengths), a measurement value individually assigned to a specific wavelength can then be generated at each measurement point, as described below. In the case of a third and fourth wavelength, a third and fourth measurement value can thus also be generated based on reflected radiation components with the respective wavelengths and, for example, taken into account when generating object information. The first and second wavelengths of the emitted radiation are at least one wavelength different from each other due to a spectral separation. The emitted first and second electromagnetic radiation (as well as any further optional electromagnetic radiation) can each encompass a wavelength range, including the respective first and second wavelengths, but these wavelength ranges are spectrally distinct from each other (i.e., do not overlap). Generally, it is envisaged that a wavelength range encompassing a defined spectral range exists that lies between the first and second electromagnetic radiation and in which no wavelengths are present, or none are relevant or usable for surface detection and / or measurement generation (for example, none detectable by the detection unit for measurement generation).Detected, convertible, or generally evaluable radiation is present or emitted. In the case of further emitted electromagnetic radiation (i.e., for example, a third and fourth radiation), it is preferably provided that at least one wavelength range comprising a defined spectral range lies between any of the emitted radiations, in which no radiation, or no radiation used for surface detection, is present or emitted. For example, a specific wavelength range can be achieved by positioning at least one filter (viewed from the object surface and along the reflected beam path) in front of the acquisition unit, filtering out radiation or its wavelengths that are not used for measurement generation or surface detection. Radiation with the corresponding wavelength(s) then no longer reaches an imaging unit of the acquisition unit and is therefore unusable for measurement generation. In other words, a filter can be provided on the receiver or acquisition side that only allows the useful signals to pass through. A multiple detection and / or imaging units can also be provided, each with its own filter, so that only the appropriately filtered radiation is used for surface detection. The filters should be selected to be different from one another, so that reflected radiation with different wavelengths can be detected and analyzed. According to one variant, the first wavelength of the first radiation lies in the range of visible red light, and the second wavelength lies in the range of visible blue light. Preferably, neither the first nor the second radiation includes any other wavelengths. These radiations are accordingly separated from each other by a wavelength range between red and blue light, within which, however, no radiation, or no radiation used for surface detection and / or relevant or usable for generating a measurement, is emitted. For all emitted electromagnetic radiations (or their associated wavelengths and / or wavelength ranges), it can be provided that two spectrally or along the wavelength spectrum successive radiations (or...)two wavelengths and / or wavelength ranges adjacent along the wavelength spectrum and belonging to one emitted radiation) are separated by at least 50 nm, at least 100 nm or at least 200 nm. The aforementioned methods allow for the provision of a radiation-free wavelength range and / or the spectral filtering of the emitted radiation. This is advantageous, for example, because the intensity of each emitted radiation can be precisely and individually adjusted, e.g., via dedicated radiation sources. The radiation with the individual wavelengths can be emitted by the radiation-generating device in the form of a so-called radiation fan, i.e., a beam that expands essentially two-dimensionally from the radiation-generating device. The extent perpendicular to the radiation fan can be negligible and / or very small, for example, comprising a few hundred µm.When such a radiation fan strikes an object surface, it is projected there as a linear and / or elongated narrow measurement field. The radiation fans can also be described as essentially triangular, with the apex of the triangle located in the area of ​​the radiation generating device. In principle, the device can thus be configured to generate at least a one-dimensional measurement field on the object surface, or, in other words, to project it onto the object surface, particularly in the form of a laser line. Such a measurement field can contain several consecutive measurement points on the object surface. The device can be a laser scanner, and in particular a laser line scanner, in which a generated measuring field is linear and / or one-dimensional and preferably has a substantially straight course (at least when irradiating a flat surface). In the case of a linear and / or one-dimensional measurement field, this can generally be defined by a series of individual measurement points. The width of such a measurement field may not exceed, or only slightly exceed, the size or diameter of the measurement points. In other words, only individual measurement points can be present along the longitudinal direction of the measurement field, without, for example, multiple measurement points being arranged perpendicular to the longitudinal direction of the measurement field. Preferably, measurement values ​​are generated for the measurement points on the object surface essentially simultaneously. An area of ​​the object surface covered by the measurement range can then be measured essentially in a single step. However, it is equally possible to project the first and second radiation sequentially and to determine a measurement value separately for the corresponding radiation or wavelength during each projection. The measuring points can generally refer to a location within a linear measuring field for which a measurement value is to be determined. The measuring points (or sampling points) can generally refer to those locations within the measuring field, and thus on the object surface, where, or in other words, for which a measurement value is to be generated. The measurement value is a distance measurement between the device and the object surface (e.g., in the form of a Z-value). If such measurement values ​​are arranged analogously to the measuring points within the measuring field, or, in other words, sequentially linked in an analogous manner, the measured area of ​​the object surface can be graphically represented based on this data. The detection device comprises at least one photosensitive unit, for example, a camera and / or a photosensitive sensor in the form of a CCD or CMOS sensor. The imaging unit can generally be planar and preferably divided into rows and columns. The imaging unit can comprise several image points or pixels for which, for example, individual intensity values ​​can be detected, with each image point having a specific row and column position (or, in other words, defined row and column coordinates). The detection device can be configured to apply triangulation principles in a known manner to determine the point of impact of the reflected radiation components at each measurement point on the photosensitive unit (e.g., computationally determined by Gaussian fitting as the location of maximum intensity).A projected measurement field, for example in the form of a line, can be mapped onto the imaging unit in a column direction, whereby a single measurement point can be mapped to a single row position along this line, or, in other words, to a single row position. Alternatively, the line can also be mapped in a row direction and the measurement point can have a column position. The detection device can comprise an individually assigned photosensitive unit (for example, a plurality of cameras) for each radiation component to be detected (or for each wavelength). According to the invention, a single photosensitive unit (for example, a single imaging or photosensitive sensor) is provided that can detect radiation with different wavelengths, wherein the radiation is directed or can be directed onto different areas of the photosensitive unit. Thus, with only one photosensitive unit, which is not necessarily color-sensitive, a plurality of measurement point-related measured values ​​can be generated due to the different impact areas, since, for example, two measurement curves described below can be projected onto the same photosensitive unit. The photosensitive unit can generally be monochrome and / or detect only a limited wavelength range encompassing a few hundred nm (e.g.,no more than 400 nm). The photosensitive unit can also be configured to perform wavelength-specific detection of the incident radiation for each pixel. For this purpose, it can be designed as a color camera or include a color-resolving photosensitive sensor. In the case of wavelength-specific detection, such color resolution allows for individual measurement generation for each detected radiation (or wavelength-specific radiation component) even if radiation with different wavelengths shares common points or areas of impact on the photosensitive unit. The detection device may include or be connected to a computing unit in order to determine a corresponding first and second measured value from the measurement signals detected for each radiation component, namely by triangulation. The detection device can be configured to generate the measured value as or based on a detected intensity (i.e., radiant flux density) of a back-reflected radiation component. In particular, this intensity can be integrated over an exposure time. According to the invention, the measured value is a distance value to the object surface (for example, a distance between the object surface and the detection device and / or the entire apparatus). This distance value is determined in a known manner by means of triangulation and based on the point of impact of the radiation in a detection plane of the detection device. The point of impact can be determined, for example, as the location of a maximum detected intensity in the detection plane and / or, for example, calculated from a detected local intensity distribution (for example, by means of a Gaussian fit as explained below).The detection plane can be defined by an imaging unit (for example, a CCD or CMOS sensor). Alternatively, the measured value can be the point of impact itself, i.e., specifying the coordinates of the point of impact within the detection plane. Another alternative is the detected and, in particular, temporally integrated intensity and / or spatial intensity distribution, which is determined for each measurement point from the reflected radiation fraction, or, in other words, a general radiation measurement value. At least the detection device and the radiation generation device can be provided in a common module, in particular in a manually or machine-operated module or handheld device, such as a manually operated laser line scanner. In other words, the detection device and the radiation generation device can be structurally integrated. For machine handling (i.e., machine-bound use, for example, on a motion device or manipulator), the modules can be arranged, for example, on a measuring machine, a robot, or a machine tool. The device may also include an information acquisition unit configured to determine object information based on the measured values, taking into account at least one of the corresponding first and second measured values ​​for each measuring point. The information acquisition unit may also be integrated into a module as described above. Alternatively, it may be provided separately (for example, as a separate computer) and connected to at least the acquisition unit via signal transmission in order to receive the determined measured values ​​from it. The object information may constitute a result data set. This data set may summarize the (measurement) information to be considered for the measurement point(s), for example, for further evaluation or presentation. In one embodiment of the device and method, the information acquisition device is configured to consider either the first or the second measured value for each measuring point. In other words, the information acquisition device can be configured to make a selection from all available measured values ​​for one (or each) measuring point. Additionally or alternatively, it can be provided that both measured values ​​are considered for one (or each) given measuring point (i.e., not just one) and, for example, calculated together (e.g., by averaging). Hybrid forms of the described variants can also be provided according to the invention, in which the information acquisition device selects between the measured values ​​for individual measuring points and considers both measured values ​​for other measuring points and, if necessary, calculates them together. For example, calculating an average value can be specified as the standard procedure, unless one of the measured values ​​meets an error criterion for a given measuring point. In that case, a selection can be made between the measured values ​​for this measuring point and / or the other measured value can be used by default. Which of the aforementioned strategies is chosen (for example, either selecting from the measured values ​​or calculating / averaging) can be determined by the user before measuring the object surface. If, for example, the user anticipates significant fluctuations in the intensity of the reflected radiation during measurement of a given object surface, selecting from the measured values ​​for each measurement point may be advantageous. Such a determination of the evaluation strategy can also constitute a separate step in the procedure described below (for example, by specifying that if an object surface possesses reflection properties that meet a predetermined limit criterion (for example, exceeding a permissible (especially local) change threshold or (especially local) gradient), a selection is made from the measured values ​​for each measurement point).This can, for example, prevent measurements taken in a saturation range of the detection device from being used as the basis for further evaluation, as these measurements were generated based on back-reflected radiation with an unacceptably high intensity. However, if spectral distortion is considered a major source of error, comparating the measured values ​​may be preferable. Furthermore, (optional) calculation or selection is possible, since the measured values ​​are distance values. If, however, the measured values ​​are intensity values, radiation measurements, or impact locations, selection may be provided and, in particular, may be the only option (i.e., no calculation option may be provided). The device and method can also propose and / or define a suitable strategy for selecting or processing the measured values. This can be done, for example, depending on the properties of the object surface to be measured, with information on these properties being obtained, for instance, from CAD data of the object. Additionally or alternatively, a test measurement with the device or other equipment can be performed on a given object surface to determine which strategy is advantageous for handling the majority of measured values ​​at each measuring point. For example, such a test measurement can determine the risk of measuring in the saturation range of the detection device and / or the potential extent of speckled areas. In summary, it can therefore be provided that various operating modes are available for handling the majority of measured values ​​for each measuring point, with the option to switch between automatic and manual modes. The selection of an operating mode can be made individually for each measuring point and / or for complete surveying operations of a given object surface or surface area. The operating modes can relate to the selection of measured values ​​as described above or to their calculation. According to the invention, however, the device and the method can also provide for the execution of only one of these operating modes (i.e., without the option to switch between multiple operating modes). The object information generated by the information acquisition device can be a summary of information intended for further processing, evaluation, and / or presentation. In particular, the object information can contain a summary of selected measurements or measurements determined based on the originally recorded measurements, e.g., by calculation. Furthermore, the object information can contain information determined based on measurements according to any of the aforementioned methods. If only one measurement point is measured, it is understood that the object information can also contain only information or one measurement point for that single measurement point. The object information can be created and / or summarized in the form of a data record.The object information can be used to create a graphic representation and / or image of the object surface, in particular to create a three-dimensional representation. Figuratively speaking, the object information can thus refer to the data set that contains the information ultimately determined for the measurement point(s), which is intended, for example, for further analysis. In other words, the object information can represent the result of selecting, calculating, or otherwise processing the multiple measurements for each measurement point in order to summarize the information to be considered for that measurement point(s) in the following analysis. Preferably, therefore, the object information for each measurement point contains only one measurement or only one piece of information that was determined from the originally available multiple measurements for that measurement point. In a further development of the device and the method, the electromagnetic radiation with the first wavelength and the electromagnetic radiation with the second wavelength are emitted simultaneously, at least temporarily, and projected onto the object surface. Additionally or alternatively, the projection or emission of the radiation can be carried out in such a way that the measurement field is formed, at least temporarily and preferably at all times, by radiation with both the first and second wavelengths. In other words, it can be provided that, at least temporarily and preferably always, radiation components with both wavelengths are projected onto the object surface. This makes it possible, for example, to ensure that at least one defined point in time exists at which measurements based on both wavelengths can be generated. Furthermore, this can reduce the total measurement time required to measure the object's surface. In this context, it can also be provided that the reflected radiation with the first and second wavelengths is detected during simultaneous illumination. In other words, the emission of the two wavelengths as well as their detection can occur at least partially overlapping in time, but in particular essentially simultaneously. Specifically, it can be provided that the detection device only performs a detection when radiation with both wavelengths is detected, thus allowing measurements to be derived based on both wavelengths. This can also contribute to reducing the total measurement time required to measure the object surface. According to a further development of the device and the method, radiation with the first wavelength and radiation with the second wavelength are directed onto the object surface at different intensities. In other words, the radiation with the first wavelength can have a lower or higher intensity than the radiation with the second wavelength. The difference between the intensities can be at least 10%, at least 30%, or at least 50%. The intensities (or the intensity difference) selected can be determined depending on the surface to be measured, in particular taking into account its material, reflectance, and / or shape. By irradiating with different intensities, it is possible to compensate for excessively low or high local reflection of the electromagnetic radiation. For example, higher-intensity radiation can be advantageous for detecting weakly reflective surface areas. To generate the final object information, the measurement obtained from the higher-intensity irradiation can then be selected for a measuring point with correspondingly low reflection. Conversely, lower intensity can be advantageous for surface areas characterized by increased reflectivity. In this case, excessive intensity can lead to overexposure and be incorrectly detected by the detection device.To generate the final object information, the measurement obtained from the lower-intensity irradiation can be selected at a measurement point with a sufficiently strong reflection. However, it goes without saying that the measurements can also be combined in this case, particularly by calculating an average. This allows the influence of any excessively strong or weak refraction to be at least partially reduced. Alternatively or additionally, it may be provided to generate different intensities by using a radiation attenuator, wherein at least one of the electromagnetic radiation with the first wavelength and the electromagnetic radiation with the second wavelength is attenuated by the radiation attenuator before being detected by the detection device. The radiation attenuator may be an optical filter that is at least partially opaque to the wavelength to be attenuated. The radiation attenuator may be positioned within or in the vicinity of the radiation generating device. Alternatively or additionally, the radiation attenuator may be positioned in or in the vicinity of the detection device, and in particular between an entrance area for incident radiation and a photosensitive unit of the detection device.This also ensures that radiation components with different intensities are available to generate the measured values. Another method for generating different intensities, which can be used as an alternative to or in combination with any of the above methods, involves providing a detection device with wavelength-specific sensitivity. For example, the detection device, and in particular a photosensitive unit thereof, can have a higher sensitivity to radiation with the first wavelength than to radiation with the second wavelength, or vice versa. Even if this radiation was originally emitted and / or reflected from the object surface with the same intensity, in this case the detection device will capture measurement signals of varying strengths, from which the measured values ​​can ultimately be derived.Thus, there is always a measurement value generated based on radiation with a lower intensity (or at least a lower detected intensity), as well as a measurement value generated based on radiation with a higher intensity (or at least a higher detected intensity). This results in analogous advantages, as explained above. According to a further development of the device and method, the radiation with the first wavelength and the radiation with the second wavelength are directed onto the object surface at an angle to each other. For example, the radiation generation device can be configured to create such an alignment by means of suitable optics and / or by angling the individual laser sources or laser diodes relative to each other. In particular, it can be provided that the radiations extend or propagate in a substantially identical spatial plane. The angle between the radiations can be chosen such that they also overlap within the spatial plane. In particular, it can be provided that the radiations each form a (preferably planar) radiation fan or are emitted as such.These radiation fans can in turn extend in an essentially identical spatial plane, but run at an angle to each other and overlap. An overlapping area of ​​the radiation and / or radiation patterns can form or contain a measurement field in which a measurement point can be determined based on both the first and second wavelengths. Starting from the radiation generating device, and especially from any wavelength-specific radiation sources, the radiation and / or radiation patterns can initially extend at a distance from each other and in the direction of the object surface to be measured. As described, they can overlap due to the chosen angle in order to provide a measurement field on the object surface within the overlapping area. Radiation components lying outside the overlapping area, however, can be disregarded during measurement generation. According to a further aspect of the device and the method, the radiation with the first wavelength and the radiation with the second wavelength are directed along or parallel to a common radiation axis onto the object surface. The radiation axis can also be referred to as the longitudinal radiation axis or propagation axis of the radiation. It can define an axis and / or direction along which the radiation propagates from the radiation-generating device and extends towards the object surface to be measured. By emitting the radiations along a common radiation axis, they can essentially propagate in a common spatial plane and / or overlap each other. In particular, related radiation fields can be substantially congruent with each other.Furthermore, the first and second electromagnetic radiation (but also any number of electromagnetic radiations, each with a specific or individual wavelength, for example an additional third or fourth electromagnetic radiation) can be coupled into each other via optical components in such a way that they extend along a common radiation axis and are imaged congruently or identically at at least one common point or as at least one common line on the object surface. To provide a common radiation axis, the radiations can be coupled into each other. This can be achieved, for example, via at least one partially reflective mirror. Particularly in the context of mechanically or manually moved devices, coupling into a common optical fiber can be provided (additionally or alternatively). A further development of the device and the method provides that the radiation with the first wavelength and the radiation with the second wavelength are directed parallel to each other onto the object surface, or, in other words, parallel to a common axis. The common axis can run between the beam or laser sources for the individual beams and / or parallel to the respective radiation axes of the beams. In this context, it is advantageous if the beams spread out from the radiation generating device, for example in the form of the described beam fans, so that an area of ​​overlap is created despite the initial parallel alignment. In particular, the beam fans can spread out after a predetermined distance in such a way that they overlap the common axis and also each other.The overlapping area then contains radiation components with both wavelengths, so that the measurement range can be defined within the overlapping area. In the device and method according to the invention, the radiation reflected from the object surface can be separated into the first and second radiation components by means of an optical separating element of the detection device. The optical separating element can comprise a beam splitter to divide the reflected radiation into its wavelength-dependent components. Not according to the invention, the separating element can be designed as a dispersion prism or can also comprise or be designed as an inclined glass plate. Alternatively, a lens of the detection device can serve as the optical separating element. In this case, lenses within the lens can refract the incident radiation differently (e.g., in the sense of chromatic aberration) and thus separate it into its wavelength components. As mentioned, in the device and method for generating object information, only one of the first or second measured value can be considered or used for at least one measuring point, provided that the considered measured value fulfills a predetermined criterion. This criterion can be a quality criterion of the measured value, which, for example, can define a predetermined minimum value. Additionally or alternatively, a total measured value can be determined for at least one measuring point based on the first and second measured values. The total measured value can be calculated in the manner described above by averaging the measured values, for example, by calculating an average and / or adding the differently weighted measured values. The selected measured value and / or the total measured value can then be incorporated into the object information and / or used to create it, or summarized in the form of object information.In other words, the object information can be generated based on the selected measurement value and / or the total measurement value. The invention further relates to a method for detecting an object surface, comprising: radiating a first electromagnetic radiation with a first wavelength and a second electromagnetic radiation with a second wavelength onto at least one measuring point of an object surface to be measured or onto an area of ​​an object surface to be measured which has at least one measuring point to be measured, wherein no radiation or no radiation used for surface detection and / or no radiation usable for generating a measurement (e.g., no radiation detectable, convertible or generally evaluable for generating a measurement) is radiated in a wavelength range between the first and second wavelength range; detecting at least one first measurement and at least one second measurement each.A measurement point is established, where the first measurement is based on radiation reflected from the object surface at the first wavelength, and the second measurement is based on radiation reflected from the object surface at the second wavelength. Additionally, a step for determining object information (e.g., regarding the three-dimensional properties of the object surface) based on at least one of the first and second measurements at each measurement point may be included. The method may include any further step and any further feature to provide all of the preceding and following interactions, operating states, and functions. In particular, any of the preceding and following explanations and further developments of the device features may also apply to, or be provided for, the corresponding method features. Furthermore, the method may be executable or be carried out with a device according to any of the preceding and following aspects. The following are an explanation of embodiments of the invention with reference to the accompanying schematic figures. Features that are identical in type and / or function may be designated with the same reference numerals across embodiments. The figures show: Fig. 1 a schematic diagram of a device according to the invention, which performs a method according to the invention, in a first embodiment; Figs. 2a-b detailed illustrations to explain a detection device of the device from Fig. 1; Fig. 3 a schematic diagram of a device according to the invention, which performs a method according to the invention, in a second embodiment; Fig. 4 a schematic diagram of a device according to the invention, which performs a method according to the invention, in a third embodiment; Figs. 5A-C illustrations to explain detectable signals in conventional solutions according to the prior art; and Fig.6A-C Illustrations to explain detectable signals in solutions according to the invention. Figure 1 shows a device 10 according to a first embodiment, which performs a method according to a variant of the invention. In the example shown, the device 10 is designed as a laser line scanner, wherein the laser line scanner is a manually or machine-operated device or is designed as an integrated manually or machine-operated unit. The device 10 comprises a radiation generation unit 17, which includes two separate beam sources 14 (or radiation generators). Each beam source 14 is configured to emit monochromatic electromagnetic radiation in the form of laser radiation and to direct it onto an object surface 16, which is only schematically indicated. Each beam source 14 is designed as a single laser diode. Furthermore, each beam source 14 can include optical elements to fan out the radiation into a line or to form the radiation fans described below. In detail, the upper beam source 14 in Fig. 1 emits monochrome laser radiation with a first wavelength along a radiation axis 18. From the laser source 14, the radiation spreads out in the form of a triangular beam fan 20. Similarly, the lower beam source 14 in Fig. 1 emits monochrome laser radiation with a second wavelength that differs from the first. This radiation travels along a radiation axis 22 and again spreads out in the form of a beam fan 24. Both beam fans 20 and 24 are two-dimensional and lie in a common spatial plane. In the case shown, the emitted radiation consists of red and blue laser radiation, each with a single wavelength in the corresponding spectral ranges of visible light (e.g., 450 nm and 640 nm). However, the use of non-visible radiation would also be possible. The wavelengths are thus spectrally distinct from one another (e.g., by a wavelength range between 450 nm and 700 nm in which no radiation is emitted). Consequently, a wavelength range exists between the emitted wavelengths in which no electromagnetic radiation suitable for surface detection or for generating measurements (e.g., no radiation usable for evaluation) is produced and emitted onto the object. Furthermore, it can be seen that the radiation axes 18 and 22 run at an angle W to each other. As a result, the radiation fields 20 and 24 also overlap. Consequently, laser radiation with both the first and second wavelengths is present in the area of ​​overlap. A possible measuring range 29 of the device 10, within which the object surface 16 can be measured with sufficient accuracy, lies in Fig. 1 between the two (virtual) boundary lines 26, 28 shown. These boundary lines 26, 28 define a section of the overlapping area of ​​the two beam fans 20, 24, in which radiation with both emitted wavelengths is present. Since, in the representation of Fig. 1, the object surface 16 is located outside the measuring range 29 limited by the boundary lines 26, 28, no meaningful object measurement can yet be carried out in the depicted state. It should also be noted that the beam fans 20; 24 in Fig. 1 are slightly inclined into the plane of the sheet. They thus run obliquely downwards with respect to the plane of the sheet. When they strike the object surface 16 in the area of ​​the measuring range 29, the incident radiation defines a one-dimensional (i.e., linear) measuring field 30, which can also be referred to as a laser line. In Fig. 1, a possible path of the linear measuring field 30 along the object surface 16 is indicated by dashed lines. This follows the contour of the object surface 16. However, such an inclination of the beam fans 20, 24 is not mandatory, since diffusely reflected radiation is also generated when the radiation strikes the object surface perpendicularly or at another angle, which can be sufficient for generating a measurement (i.e., diffusely reflected radiation is generated, in particular in the direction of the detection unit). The measuring field 30 contains several consecutive measuring points 32, which can also be referred to as sampling points. It should be noted again that the measuring field 30, shown only as an example, only forms on the object surface 16 and can only be evaluated for precise measurement when the object is moved closer to the radiation generating device 17 than shown in Fig. 1 and is preferably positioned within the measuring range 29. The radiation contained in the measuring field 30 is reflected from the object surface 16 towards a detection device 31, which is explained below with reference to Fig. 2a. In particular, both radiation (or a portion thereof) with the first wavelength and radiation (or a portion thereof) with the second wavelength are reflected towards the detection device 31. At the measuring points 32, a distance value between the detection device 31 and the object surface 16 is then determined according to a conventional triangulation principle. The position and / or distribution of the measuring points 32 is determined, for example, by the resolution of the detection device 31 and is shown in Fig. 1 only as an example. Fig. 2a shows a view of the device 10 rotated 90° into the plane of the sheet relative to Fig. 1. The two radiation sources 14 of the radiation generating device 17 are therefore arranged one behind the other, with only the lower radiation source 14 from Fig. 1 being visible in Fig. 2a. The beam path of the radiation fans 20, 24 is visible; in the view shown, it is linear and extends towards the object surface 16. Furthermore, the positions of the boundary lines 26, 28, which limit the measuring range 29, are marked. Furthermore, the detection device 31, which comprises a planar photosensitive unit 34, can be seen. Examples of such a photosensitive unit 34 are a CCD or CMOS sensor. For illustrative purposes, Fig. 2a also shows a possible beam path originating from the positions of the boundary lines 26, 28. The beam paths each represent the path of reflected radiation components containing both radiation with the first and the second wavelength when the object surface 16 is positioned at the corresponding boundary lines 26, 28. Specifically, it can be seen that a possible reflected radiation component originating from the left boundary line 26 in Fig. 2a falls on a lower edge region of the photosensitive unit 34. There, it forms a line on the photosensitive unit 34 extending into the plane of the sheet and thus in the column direction of the photosensitive unit 34, which runs in the row direction of the photosensitive unit 34 (i.e.,in the plane of the leaf) each measuring point 32 has a Gaussian-like intensity distribution (see also the following Fig. 5A-C and Fig. 6A-C ). A reflected radiation component emanating from the right boundary line 28 in Fig. 2a, however, falls on an upper edge region of the photosensitive unit 34 and forms an analogous line there, as in the case of the left boundary line 26. Radiation components that are reflected from points lying outside the boundary lines 26, 28 or the measurement field 29 are consequently no longer detectable by the photosensitive unit 34, since they no longer fall on the area defined here (i.e., they would pass by the edge regions or run outside of them). In a manner known per se, the distance of the detection unit 31 from the individual measurement points 32 on the object surface 16 can be calculated from the measurement point-specific locations of the radiation impacting the photosensitive unit 34 using a triangulation principle. If the detection unit 31 is positioned stationary within the device 10, the distance of the device 10, or any other units thereof, from the object surface 16 (or the measurement points 32 located therein) can also be calculated. In the case shown, a corresponding distance value constitutes the measured value for each measurement point 32, which is acquired by the detection device 31 (for example, a computing unit thereof, not shown separately) and / or calculated by triangulation. Since such triangulation is known per se, a more detailed explanation is omitted here.However, a special feature of the case shown is that for each measuring point 32 a corresponding distance value based on radiation with the first wavelength as well as a distance value based on radiation with the second wavelength is recorded (see also the following explanation of Fig. 2b). An information acquisition device 60, which is configured to determine object information of the object surface 16 based on the measured values ​​and / or to summarize all available measured values ​​for further evaluation, is only schematically indicated in Fig. 1. The information acquisition device 60 is also integrated into the device 10 and is connected to the acquisition device 31 described below via data transmission. Finally, it should be noted that in the case shown, the radiation with the first and the radiation with the second wavelength are emitted simultaneously by the radiation generating device 17 and directed onto the object surface 16. Furthermore, the corresponding reflected radiation components 40, 44 are also detected by the detection unit 31 in a temporally overlapping manner. Overall, the number of measured values ​​recorded at each measuring point 32 can thus be doubled without a significant increase in measurement time. The reflected radiation striking the photosensitive unit 34 therefore always contains components of both radiations originally emitted by the radiation-generating device 17 and thus also of both associated wavelengths. In order to acquire an individual (i.e., wavelength-specific) measurement value for each wavelength, the sensing device 31 includes an optical separating element 36 in the form of a dispersion prism, which is only schematically indicated. The separating element 36 is positioned such that the reflected radiation passes through it before striking the photosensitive unit 34. The effect of the separating element 36 becomes clear from the schematic diagram in Fig. 2b. The detection device 31 is again visible, as is radiation 38 reflected from the object surface 16 (not shown in this illustration), which enters the detection device 31. There, the reflected radiation 38 passes through the separating element 36 in the form of the dispersion prism and is subsequently split into its wavelength-specific radiation components. Specifically, a first radiation (or first radiation component) 40 is shown, which strikes the photosensitive unit 34 at an upper point 42 in Fig. 2b. Furthermore, a second radiation (or second radiation component) 44 is shown, which strikes the photosensitive unit 34 at a point 46 offset from the upper point 42. The first and second radiations 40, 44 have different wavelengths, which are identical to the originally emitted wavelengths. In the case shown, one radiation 40 is radiation with the originally emitted first wavelength, and the other radiation 44 is radiation with the originally emitted second wavelength. For the sake of clarity, it is assumed in this context that the radiations 40, 44 are due to reflections at individual measuring points 32.In fact, with a projected line, line-shaped radiation components would also be reflected and corresponding impact lines (and not just individual impact points 42, 46) would be imaged on the photosensitive unit 34. Since the points of impact 42, 46 on the photosensitive unit 34 are not located at different points (or are locally disputed), individual measured values ​​in the form of the distance values ​​explained above can be determined for each of the radiations 40, 44 and thus for each of the first and second wavelengths. Alternatively, the measured values ​​can relate to the intensity values ​​and / or intensity value maxima explained below, or to the points of impact determined therefrom. In detail, the photosensitive unit 34 in the case shown is divided into individual areas A and B. These areas are defined such that radiation 40 generated or reflected within the measuring area 29 of the device 10, comprising only radiation with the first wavelength, always strikes the photosensitive unit 34 within area A after passing through the separating element 36. Reflected radiation 44 with the second wavelength, on the other hand, always strikes the photosensitive unit 34 in the second area B, provided it is reflected from the object surface 16 from a position within the measuring area 29 of the device 10. In other words, the reflected radiation components 40, 44 with the different wavelengths (and also any lines imaged on the photosensitive unit 34) are directed onto different areas A, B of the photosensitive unit 34 and thus separated spatially. However, it is also possible to provide individual photosensitive units 34 for each radiation component 40, 44 and its associated wavelength, with the individual photosensitive units 34 being positioned, for example, according to areas A, B in Fig. 2b. Finally, it should be noted that corresponding areas A, B can also be positioned on both sides of a central axis M, as shown in Fig. 2a, in order to capture all possible deflections or refractions of the radiation components 40, 44 by the separating element 36. Additionally or alternatively, areas A, B can also overlap at least partially, whereby radiation incident in the overlap area can be split into or assigned to the individual wavelengths, e.g., by using detection pixels (e.g., RGB pixels) with different wavelength sensitivities. As explained above, due to the effect of the prism 36, the radiation can, in principle, be imaged onto spatially separated areas of one and the same detection device 31 or photosensitive unit 34. The latter therefore does not necessarily have to be color-sensitive, but can, for example, be...It may be designed as a monochrome camera and / or only capture a limited wavelength range, e.g., 400–800 nm. In this case, a multitude of measured values ​​per (object) measurement point can be generated from the majority of the captured radiation components or measurement curves. If a precise correlation of these measured values ​​to the emitted wavelength is desired (which is not strictly necessary), calibration information and / or information about the object geometry can be used, for example. As a result, the device 10 of the illustrated embodiment can scan and detect the object surface 16 without contact. It determines distance values ​​for a plurality of measuring points 32, which can be used in a known manner to define a 3D point cloud of the object surface 16 and / or to generate information about or representations of a three-dimensional shape of the object surface 16. As described, the device 10 emits radiation with a first wavelength and radiation with a second wavelength. For each of these radiations or wavelengths, a separate and thus individual measured value is then determined for each measuring point 32. This is achieved by dividing the reflected radiation 38 into radiation components 40, 44 with the first and second wavelengths, respectively, as explained with reference to Fig. 2b. To ultimately generate object information for further measurement evaluation and / or as a result data set, for each of the measurement points 32 in the measurement field 30, either the measurement value generated based on the radiation 40 with the first wavelength or the measurement value generated based on the radiation 44 with the second wavelength can be considered. It is also possible to consider both of these measurement values ​​and, for example, calculate an average value. The choice of the final strategy for handling the multiple measurement values ​​per measurement point 32 can be made according to any of the variants generally described above. By way of example only, calculating an average value for the multiple measurement values ​​per measurement point 32 might be preferred if it is assumed that there is a high potential for measurement distortions due to the speckled light phenomena described above.According to the invention, in this case the probability is increased that at least one of the emitted radiations exhibits no or only slightly pronounced spectral defects at a considered measuring point 32, and that thus usable (total) measured values ​​(or object information) can be determined for this measuring point. This applies in particular compared to the case where only a single radiation is present, by means of which, in the case of spectral defects, usable measured values ​​may not be obtainable for every measuring point 32. In the case shown, the device 10 is further configured to select different intensities (or beam flux density) for the emitted radiation with the first wavelength and the emitted radiation with the second wavelength. However, the device 10 can also essentially equalize the intensities of the radiations. In particular, it can be provided that the device 10 can be operated either in an operating mode in which different intensities are provided or in an operating mode in which similar or identical intensities are provided. The selection of a suitable operating mode can, for example, be made by an operator of the device 10. The procedure for measuring the object surface 16 is analogous to the variant described above, even in the case of different intensities. More precisely, wavelength-specific measured values ​​are again generated for each measuring point 32 of the measuring field 30, with one being based on radiation with a higher intensity and the other on radiation with a lower intensity. If the object surface 16 exhibits strongly varying reflectances, this can potentially be compensated for by selecting different intensities. For example, if a measuring point 32 is located in an area with a high reflectance, radiation with a high intensity can lead to radiation 40, 44 that lies in a saturation region of the photosensitive unit 34 and consequently no longer allows for accurate measurement.In this case, the radiation 40, 44 with the lower intensity would have to be used to generate the final object information. However, with a low reflectance, radiation 40, 44 with a low intensity can make it difficult to acquire a suitable measurement, so the radiation 40, 44 with the higher intensity would have to be used to generate the final object information. In summary, in the variant with different radiation intensities, it can therefore be provided that a selection is made between the 32 measured values ​​generated at each measuring point, for example by the information acquisition device 60. To provide the different intensities, either the radiation sources 14 can be appropriately controlled so that they emit radiation at different intensities. Alternatively or additionally, a radiation attenuator 55 can be provided, which attenuates at least one of the radiations emitted by the radiation sources 14 before it is detected by the photosensitive unit 34. A possible position of a radiation attenuator 55 in the form of an optical filter is schematically indicated in Fig. 2b. The filter is arranged within the detection device 31 such that incident radiation passes through the filter before striking the photosensitive unit 34. Such an optical filter can also be positioned between one of the radiation sources 14 and the object surface 16, but preferably outside the overlapping area of ​​the beam fans 20, 24. Alternative embodiments are explained below with reference to Figures 3 and 4. The differences from the preceding embodiment are limited to the radiation generation device 17. The detection device 31 and the general measurement procedure, however, are analogous to the preceding example and are therefore not explained again. Figure 3 shows a radiation generating device 17 according to a second embodiment. This device again comprises two beam sources 14. One of the beam sources 14 emits monochromatic electromagnetic radiation with a first wavelength (e.g., a red laser beam), while the other beam source 14 emits monochromatic radiation with a second wavelength (e.g., a blue laser beam). The beam sources 14 are optically connected to a beam coupler 16. The emitted radiations are coupled together via the beam coupler 16 and emitted towards an object surface 16 (not shown). This occurs such that both radiations extend along a common radiation axis 18, 22 and spread out in the form of congruent beam fans 20, 24. At every spatial position of the emitted radiation, radiation with both the first and second wavelengths is present. If an object surface 16 is positioned within the congruent beam area 20, 24 and preferably within a measuring area 29 of the device 10 (not shown), wavelength-specific measured values ​​can be acquired at each measuring point 32 as described above. Figure 4 shows another embodiment of the device 10, in which the radiation generating unit 17 again comprises two beam sources 14. The beam sources 14 are positioned next to each other and emit electromagnetic radiation into the environment (and not into a possible optical fiber or beam coupler 16 as in Figure 3). More precisely, one of the beam sources 14 emits monochromatic radiation with a first wavelength (e.g., a red laser beam), while the second beam source 14 emits monochromatic radiation with a second wavelength (e.g., a blue laser beam). The radiations then spread out in the form of two-dimensional radiation fans 20, 24. In the case shown, these radiation fans 20, 24, or rather the associated radiation axes 18, 22, run parallel to each other and also parallel to a common axis 50 of the radiation generating unit 17.The radiation sources 14 are positioned such that their radiation fields 20, 24 overlap in the region of the common axis 50. In the area of ​​overlap, radiation with both the first and second wavelengths is again present. If an object surface 16 is positioned in this area of ​​overlap, and preferably in a defined measuring area 29 of the device 10 (not shown), wavelength-specific measured values ​​can again be determined for each measuring point 32. Furthermore, it should be noted that the use of an optical separator 36, as explained above with reference to Figs. 2a and 2b, is not mandatory. Instead, a color-sensitive photosensitive unit 34 can also be used (e.g., in a detection device 31 in the form of a color camera). This unit can determine the intensity of the individual colors (or wavelengths) within the incident radiation 38 at each point of impact 42, 46 in a known manner, and in particular determine an intensity distribution over a spectrum with multiple wavelengths (e.g., over the visible spectrum). This applies especially to the case where each point of impact 42, 46 on the photosensitive unit 34 is defined by a pixel containing a plurality of detector units, each detector unit being sensitive to several individual wavelengths or colors (e.g., a so-called RGB pixel or detector pixel).Thus, for each point of impact 42, 46 on the photosensitive unit 34, the impact intensity can be determined separately for each of the different wavelengths, from which in turn a wavelength-specific measured value can be determined for each measuring point 32. Figures 5A-C show diagrams illustrating signals that can be detected using conventional, prior art solutions. Each figure depicts a row-wise intensity distribution composed of intensity values ​​detected at individual pixel positions in a row of the detection device 31 (and, in particular, a photosensitive unit 34 or sensor area thereof). The intensity values ​​for each pixel position are marked with unfilled circles. In a manner known per se, each row (or row signal) of the detection device 31 is assigned to a single measurement point 32 on the object surface 16, whereas, in the column direction of the detection device 31, the signals (or intensity distributions) received for each measurement point 32 are arranged in a row. As described, the laser line projected onto the object surface 16 and reflected back from it is thus depicted in the column direction. Consequently, in Fig. 5A, the light reflected back from the object surface 16 is detected by the detection device 31 in such a way that a line-wise intensity distribution is obtained for a single measurement point 32, in which a single intensity value is present for each pixel or each pixel position in the line direction. The intensity value can be specified as a grayscale value. Here, the incident intensity is integrated to obtain the intensity value over an exposure time, which in the case shown is assumed to be constant. Subsequently, based on the correspondingly determined discrete spatial distribution of the intensity values ​​(see unfilled circles in Fig. 5A), a Gaussian distribution of the intensity is calculated, for example, using a conventional Gaussian fit or, in other words, a conventional Gaussian curve fitting. The actual maximum intensity value is thus determined computationally and is represented by a filled circle in Fig. 5A. A computationally determined point of impact (or pixel position) of the maximum intensity in the considered row of the detection device is also assigned to this maximum value. In the case shown, this point of impact is at approximately 10.3 and is also used as the basis for further triangulation in a manner known per se (i.e., assigned to a considered measurement point 32 as the actual point of impact). The described procedure can also be referred to as the light section method. Figure 5A shows the case of conventional radiation reflection from an object surface 16. In Figure 5B, however, an unusually highly reflective object surface 16 is irradiated. It can be seen that intensity values ​​are obtained between pixel positions 8 and 13 that lie within a saturation range of the detection device. Consequently, a maximum intensity value is output at each of these pixel positions, even though the points on the surface from which the radiation components detected at pixel positions 8 to 13 are reflected may be detected to varying degrees by the detection device 31. However, these different distances can no longer be detected and reconstructed by the sensor due to the saturation range being reached. Attempting to perform a Gaussian fit based on the intensity distribution from Fig. 5B would (if successful at all) result in a plateau-like intensity distribution in the area of ​​pixel positions 9 to 11, since the maximum detectable intensity is present there. Accordingly, one would not be able to determine a single maximum intensity value, but only a range of values ​​for the maximum intensity (see the filled circles in Fig. 5B). It is therefore not possible (or at least not possible with sufficient accuracy) to identify a single point of impact with the maximum intensity, assign it to a considered measurement point 32, and use it for triangulation. Instead, an arbitrary location between pixels 9 and 11 would have to be selected, which correspondingly reduces the achievable accuracy. Figure 5C further illustrates the case of a weakly reflective surface. In this case, it can be seen that the intensity values ​​are so low that, again, only a maximum value distribution can be observed in the area of ​​pixel positions 9 to 11 (see filled circles). Therefore, once again, an arbitrary location between pixels 9 to 11 must be selected, instead of being able to precisely determine the actual location where the maximum intensity occurs. Figures 6A-6C show illustrations to explain the signals detectable according to the invention. Figure 6A shows, firstly, an intensity distribution of the emitted radiation on the object surface 16 or along individual object positions. Such an intensity distribution can occur perpendicular to the laser line direction and be present in the area of ​​a single measurement point 32 to be detected. It can be seen that radiation with a first wavelength 100 and radiation with a second wavelength 120 is emitted. Viewed along the object surface, the incident radiation intensity is again Gaussian distributed, with the radiation with the first wavelength 100 generally having a higher intensity than the radiation with the second wavelength 120. Figures 6B-6C show line-wise intensity distributions analogous to Figures 5A-C (i.e., intensity distributions determined for a single measurement point 32), which can be detected by the detection device 31 based on the back-reflected radiation. Since the back-reflected radiation is separated into individual radiation components 40, 44 by means of the prism or the separating element 36 described above, two spatially separated Gaussian intensity distributions are also generated on the photosensitive unit or the sensor surface of the detection device 31. These intensity distributions are arranged according to the impact areas A, B from Figure 2b. Figure 6B shows a sensor-acquired intensity distribution for a weakly reflective object surface 16. It can be seen that high intensity values ​​are measured for the first wavelength 100 in the area of ​​pixel positions 4 to 5. Based on the irradiation with the second wavelength 120, which was emitted with a significantly lower intensity (see Figure 6A), only very low intensities, barely evaluable, are determined in the area of ​​pixel positions 14 to 16. The computational evaluation is therefore limited to the intensity distribution on the left in Figure 6B, which was generated based on the radiation with the first wavelength 100. Based on this, a maximum intensity value can again be calculated and is represented by a filled circle (approximately at pixel positions 4 and 8). This can be used as the computationally determined point of impact for the considered measurement point 32 as the basis for further triangulation. Figure 6C shows the case of a highly reflective object surface 16. In this case, the radiation with the first wavelength 100, due to its higher intensity, leads to the same saturation phenomenon in its corresponding area of ​​incidence between pixel positions 1 to 9 as described in Figure 5B. Based on the reflected radiation with the second wavelength 120, however, a precisely evaluable Gaussian intensity distribution is obtained in the corresponding area of ​​incidence between pixel positions 11 to 19, for which the point of incidence of maximum intensity can be calculated in the manner described above (approximately at 15.2). It is understood that the above row-wise considerations can be carried out for each row and thus for each measuring point 32, wherein the measuring points 32 or the row-wise intensity distributions determined for them are arranged in the column direction of the recording device 31. This demonstrates that the presented solution enables the reliable measurement of object surfaces with a wide variety of properties.

Claims

Device (10) for detecting an object surface (16), comprising: a radiation generating device (17) with at least one radiation source (12), wherein the radiation generating device (17) is configured to emit first electromagnetic radiation with a first wavelength and second electromagnetic radiation with a second wavelength onto a linear measuring field on an object surface (16) with at least one measuring point (32) of the object surface (16) to be measured or an area of ​​the object surface (16) to be measured, which has at least one measuring point (32) to be measured, wherein the radiation generating device (17) is configured to emit no radiation or radiation used for surface detection onto the measuring point (32) to be measured or onto the area of ​​the object surface (16) in a wavelength range between the first wavelength and the second wavelength.such that the first and second wavelengths are different from each other; and a detection device (31) configured to detect at least one first measurement value and at least one second measurement value for each of the measurement points (32) to be measured, wherein the first measurement value is based on radiation with the first wavelength reflected from the object surface (16) and the second measurement value is based on radiation with the second wavelength reflected from the object surface (16), characterized in that the first and second measurement values ​​are each distance values ​​to the object surface (16) and are determined by triangulation, wherein the detection device (31) comprises an optical separating element (36) to divide the radiation reflected from the object surface (16) into a first and a second radiation component (40, 44), wherein the detection device (31) comprises a photosensitive unit (34),wherein the radiation components (40, 44) separated by means of the optical separating element (36) strike the photosensitive unit (34) at offset points of impact (42, 46), wherein the optical separating element (36) is a dispersion prism or an objective of the detection device (31) serves as the optical separating element (36). Device (10) according to claim 1, wherein the radiation generating device (17) is configured to emit the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength at least temporarily simultaneously onto the object surface (16). Device (10) according to claim 2, wherein the detection device (31) is configured to detect the reflected radiation with the first and the second wavelength during simultaneous illumination. Device (10) according to one of the preceding claims, wherein the device (10) is configured to emit the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength at different intensities onto the object surface (16). Device (10) according to one of the preceding claims, further comprising a radiation attenuator (55) to attenuate at least one of the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength before detection by the detection device (31); and / or wherein the detection device (31) has different sensitivities for the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength. Device (10) according to one of the preceding claims, wherein the radiation generating device (17) is configured to emit the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength at an angle to each other onto the object surface (16) such that the radiations overlap. Device (10) according to one of claims 1 to 5, wherein the radiation generating device (17) is configured to emit the first electromagnetic radiation with the first wavelength and the second electromagnetic radiation with the second wavelength substantially along or parallel to a common radiation axis (18, 22) onto the object surface (16). Device (10) according to one of the preceding claims, further comprising an information acquisition device (60) which is configured to determine object information based on the measured values, wherein at least one of the corresponding first and second measured values ​​is taken into account for the or for each of the measuring points (32). Device (10) according to claim 8, wherein the information acquisition device (60) is configured to consider only one of the first or second measured value for at least one measuring point (32) and / or to determine a total measured value for at least one measuring point (32) based on the first and the second measured value. Device (10) according to one of the preceding claims, wherein the radiation generating device (17) comprises a first radiation source (12) for generating the first electromagnetic radiation and a second radiation source (12) for generating the second electromagnetic radiation, and wherein the radiation sources (12) are each configured as laser sources. Device (10) according to one of the preceding claims, wherein the wavelength range in which no radiation is emitted and which lies between the first and the second wavelength comprises at least 50 nm, at least 100 nm or at least 200 nm. A method for sensing an object surface (16), comprising: - shining a first electromagnetic radiation with a first wavelength and a second electromagnetic radiation with a second wavelength onto a linear measuring field on an object surface (16) with at least one measuring point (32) of the object surface (16) to be measured or with a measuring area of ​​the object surface (16) that has at least one measuring point (32) to be measured, wherein in a wavelength range between the first wavelength and the second wavelength no radiation or radiation used for surface sensing is shining onto the measuring point (32) to be measured or onto the area of ​​the object surface (16) to be measured, such that the first and the second wavelengths are different from each other; - acquiring at least one first measured value and at least one second measured value for the measuring point (32) or each of the measuring points (32),wherein the first measurement (32) is based on radiation with the first wavelength reflected from the object surface (16) and the second measurement is based on radiation with the second wavelength reflected from the object surface (16), characterized in that the first and second measurement values ​​are each distance values ​​to the object surface (16) and are determined by triangulation, wherein the detection device (31) comprises an optical separating element (36) to divide the radiation reflected from the object surface (16) into a first and a second radiation component (40, 44), wherein the detection device (31) comprises a photosensitive unit (34), wherein the radiation components (40, 44) separated by means of the optical separating element (36) strike the photosensitive unit (34) at offset points of impact (42, 46).wherein the optical separating element (36) is a dispersion prism or a lens of the detection device (31) serves as the optical separating element (36).

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