Device and method for inspecting optical properties of surface

Abstract

The invention relates to a device (1) for inspecting an optical property of a surface, comprising: first radiation means (2) adapted and intended to irradiate radiation onto the surface to be inspected in an irradiation direction (R1) characterized by a first irradiation angle (a1); first radiation detection means (12) adapted and intended to detect radiation emitted, and in particular scattered, from the surface (10) to be inspected at a first emission angle (b1) in response to the irradiated radiation; and second radiation detection means (14) adapted and intended to detect radiation emitted from the surface (10) to be inspected at a second emission angle (b2) in response to the irradiated radiation, characterized in that the apparatus (1) has second radiation means (4) adapted and intended to irradiate radiation onto the surface to be inspected in a second irradiation direction (R2), the second irradiation direction is characterized by a second irradiation angle (a2), the first irradiation angle (a1) and the second irradiation angle (a2) being substantially mirror-inverted with respect to a direction perpendicular to the surface to be inspected.

Description

Technical Field

[0001] This invention relates to apparatus and methods for inspecting surface properties. Surfaces, such as the surfaces of motor vehicles, have different surface properties. In particular, the visual impression of such surfaces varies greatly depending on the incidence of different light. Background Technology

[0002] Various devices and methods are known in the prior art for inspecting the optical surface properties of objects such as motor vehicles and other objects such as furniture. Typically, light is irradiated onto the surface to be inspected, and one or more intensity sensors detect the radiation scattered and / or reflected by the surface to obtain an impression of the surface properties.

[0003] It can check different characteristics, such as gloss, orange peel, color impression, etc.

[0004] This invention is based on the aim of making existing devices for inspecting surface properties more versatile. According to the invention, this is achieved through the subject matter of the independent patent claims. Advantageous embodiments and further developments are the subject matter of the dependent claims.

[0005] Another application concerns the evaluation of so-called retroreflective surfaces. Here, for example, measurements are taken on special effect pigments that reflect incident light back, and in particular, reflect incident light back regardless of the direction of incidence.

[0006] Furthermore, coatings or surfaces using crystalline glass pigments have recently become known, sometimes in combination with known metallic particles. Such coatings can significantly improve the visibility of objects for both humans and machines, such as those using so-called LIDAR (Light Detection and Ranging) systems. These crystalline glass pigments can be special beads embedded in a solution.

[0007] Optical inspection and evaluation of such surfaces is not easy using equipment and methods known from the prior art, because high precision is required on the one hand, and the local arrangement, size, or orientation of the pigment must also be detected with high accuracy on the other. In particular, it should be noted that such surfaces are sometimes curved. Summary of the Invention

[0008] The apparatus for inspecting the optical properties of a surface according to the invention includes a first radiating device adapted and intended to irradiate radiation onto the surface to be inspected along a first irradiation direction characterized by a first irradiation angle.

[0009] Furthermore, a first radiation detection device is provided, which is adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a first emission angle in response to irradiation. Preferably, the first radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiation.

[0010] Furthermore, a second radiation detection device is provided, adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a second emission angle in response to radiation irradiated (by the first radiation device). Preferably, this second radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiated radiation.

[0011] According to the invention, the device includes a second radiating device adapted and intended to irradiate radiation onto a surface to be inspected along a second irradiation direction, the second irradiation direction being characterized by a second irradiation angle, wherein the first irradiation angle and the second irradiation angle are substantially opposite to each other with respect to a direction perpendicular to the surface to be inspected.

[0012] An additional device according to the invention for inspecting the optical properties of a surface includes a first radiating device adapted and intended to irradiate radiation onto the surface to be inspected along a first irradiation direction characterized by a first irradiation angle.

[0013] Furthermore, a first radiation detection device is provided, which is adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a first emission angle in response to irradiation. Preferably, the first radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiation.

[0014] Furthermore, a second radiation detection device is provided, adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a second emission angle in response to radiation irradiated (by the first radiation device). Preferably, this second radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiated radiation.

[0015] According to the invention, the device has an additional radiation detection device adapted and designed to detect radiation emitted from and, in particular, reflected from the surface to be inspected in response to irradiated radiation in an emission direction characterized by an additional emission angle, wherein the irradiation direction and the emission direction are substantially opposite to each other.

[0016] In this creative design, it is therefore recommended to observe light or radiation emitted from the surface in the opposite direction to the incident direction.

[0017] In a preferred embodiment, the surface is provided with pigments, particularly effect pigments and / or reflective particles.

[0018] Particularly preferably, the surface is a surface that reflects at least a portion, and preferably a majority, of the irradiated radiation (particularly regardless of the irradiation direction), wherein the surface also reflects a large portion of the radiation in a direction opposite to the irradiation direction, even if the irradiation direction is not perpendicular to the surface, but deviates from the perpendicular direction by an angle of at least 10°, preferably at least 20°, preferably at least 30°. This portion is particularly larger than the radiation scattered along this direction.

[0019] In another preferred embodiment, the device includes a control device that causes radiation emitted by the first radiating device to impinge on the surface and causes radiation emitted by the surface in response to the irradiation to impinge on a further radiation detection device.

[0020] In another preferred embodiment, the control device is adapted and intended to control a further radiation detection device in such a way that the further radiation detection device receives radiation emitted by the first radiation device and reflected by the surface, and preferably outputs at least one signal representing the characteristics of the radiation.

[0021] The additional radiation detection device is preferably adapted and intended to record a spatially resolved image of the radiation incident on the additional radiation detection device. In another preferred embodiment, the additional radiation detection device is adapted and intended to output at least one signal representing a characteristic of the intensity of the radiation incident on the additional radiation detection device.

[0022] Preferably, the control device controls the additional radiation detection device in such a way that the additional detection device is activated when the first radiation device emits radiation, i.e., the additional detection device is activated temporarily for at least the same time period.

[0023] In another preferred embodiment, an additional radiation detection device is adapted and designed to detect radiation in the visible wavelength range.

[0024] In another preferred embodiment, the additional radiation detection device is adapted and intended to detect radiation in the infrared wavelength range, and particularly in the near-infrared wavelength range. In another preferred embodiment, the additional radiation detection device is adapted and intended to detect radiation in the wavelength range of 880 nm to 930 nm, preferably in the wavelength range of 890 nm to 920 nm, and particularly preferably in the wavelength range of 900 nm to 910 nm.

[0025] In another preferred embodiment, the additional radiation detection device includes a silicon-based sensor device.

[0026] The surface to be inspected is preferably a painted surface, and in particular a surface coated with an effect paint.

[0027] The radiation is preferably light, and especially light in the visible wavelength range, or light that is at least contained in the visible wavelength range.

[0028] A method has been proposed that not only radiation is irradiated onto a surface from a specific irradiation direction, but also, conversely, radiation reflected and / or emitted from the surface in a direction opposite to that first irradiation direction, and especially reflected radiation. This method is unusual because attempts are usually made to separate the irradiation direction and the reflection direction from each other.

[0029] However, the advantages of this method are that, on the one hand, scattered light and different directions can be detected; and on the other hand, the same device can also be used to determine gloss effects (or more generally, effects observed in reflections).

[0030] In a preferred embodiment, the first radiating device is adapted and intended to preferably use a filter device, and in particular a filter wheel as described in more detail below, to emit continuous or sustained monochromatic light or substantially monochromatic light of various wavelengths, as described in more detail below. In this way, the first radiating device is particularly suitable for color measurement at different angles. “Monochromatic light” is understood to specifically mean light having a predetermined wavelength or, in particular, a narrow wavelength range. Preferably, this wavelength range includes less than 50 nm, more preferably less than 40 nm, particularly preferably less than 30 nm, and particularly preferably less than 20 nm.

[0031] The second radiation device is preferably white light illumination or has such illumination. The second radiation device is preferably used for camera measurements under vertical observation.

[0032] On the other hand, this application also relates to an additional use of the second radiating device for performing gloss measurement by using the path also used for illumination as a detection path.

[0033] However, an additional radiation detection device can be used alongside the second radiation device, or another radiation detection device can be used in place of the second radiation device. In this way, the first radiation device can be used for the additional purpose of measuring gloss, as described above.

[0034] The apparatus according to the invention for inspecting the optical properties of a surface includes a first radiating device adapted and intended to irradiate radiation onto the surface to be inspected along a first irradiation direction characterized by a first irradiation angle.

[0035] Furthermore, a first radiation detection device is provided, which is adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a first emission angle in response to irradiation. Preferably, the first radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiation.

[0036] Furthermore, a second radiation detection device is provided, adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a second emission angle in response to radiation irradiated (by the first radiation device). Preferably, this second radiation detection device (particularly due to its positioning) is not adapted to detect radiation reflected from the surface to be inspected at a first emission angle in response to irradiated radiation.

[0037] According to the invention, the device includes an additional radiation detection device adapted and intended to detect radiation reflected from the surface along an additional emission direction characterized by an additional emission angle, wherein the first irradiation angle and the additional emission angle are substantially opposite to each other with respect to a direction perpendicular to the surface to be inspected.

[0038] In this case, an additional radiation device is also preferably used for gloss measurement. In this configuration, it is preferable to provide an additional deflection device and / or beam splitter device between the surface and the additional radiation detection device.

[0039] Preferably, the device includes a control device that causes the light irradiated by the first radiating device and the light irradiated by the second radiating device to occur at different times and / or at different time periods.

[0040] The device is preferably a portable device. However, for example, the device can also be mounted on a robot or robotic arm, allowing it to be guided above a surface. The second radiating device is preferably at least one LED, and particularly at least one white LED.

[0041] Preferably, the first radiation device and the second radiation device are symmetrical to each other with respect to a plane perpendicular to the surface to be inspected.

[0042] Particularly preferably, at least one lens is arranged in the beam path between the first radiating device and the surface. Preferably, at least two lenses are arranged in the beam path between the first radiating device and the surface.

[0043] "Substantially opposite" means that the first angle of the two angles has a predetermined size, and the opposite angle deviates from the completely opposite position by no more than 5°, preferably no more than 4°, preferably no more than 3°, preferably no more than 2°, and particularly preferably less than 1°.

[0044] In another preferred embodiment, the second radiating device is positioned such that the radiation emitted by the second radiating device is reflected by the surface to be inspected in a direction opposite to the first irradiation direction.

[0045] In another preferred embodiment, a first radiation device is arranged in a first radiation arm, a second radiation device is arranged in a second radiation arm, and the two radiation arms are symmetrical with respect to the plane perpendicular to the surface to be inspected.

[0046] In another preferred embodiment, the device has an additional (radiation) detection device adapted and designed to detect radiation emitted by the second radiation device and reflected by the surface to be inspected. Therefore, this is radiation propagating in a direction opposite to the aforementioned first irradiation direction (at least in the section).

[0047] The additional radiation detection device preferably includes a photodiode. Preferably, a radiation deflection element, such as a mirror, is provided in the beam path between the surface to be inspected and the additional (radiation) detection device, the radiation deflection element deflecting the radiation reflected from the surface in the direction of the additional (radiation) detection device.

[0048] In another preferred embodiment, the device has a housing in which a first radiation device, a first radiation detection device, a second radiation detection device, and, more preferably, another (radiation) detection device are arranged.

[0049] Particularly preferably, the housing has an opening through which the first radiating device illuminates the surface to be inspected. Particularly preferably, light or radiation scattered or reflected by the surface also re-enters the housing through the opening.

[0050] Particularly preferably, the opening can be placed against the surface to be inspected such that, during measurement, the surface is preferably substantially just outside the opening or substantially just outside the housing.

[0051] In another advantageous embodiment, the interior of the housing is radiation-absorbing, for example, black.

[0052] Preferably, all of the above-described radiating devices emit light onto the surface through the aforementioned openings. Particularly preferably, the aforementioned openings are the only openings within the housing through which radiation can enter the housing.

[0053] In another preferred embodiment, the first radiating device is adapted and intended to emit radiation of different colors. For this purpose, the first radiating device may have multiple LEDs in different colors. In this way, the surface can be illuminated with different colors.

[0054] However, particularly preferably, the first radiating device has a light source and a plurality of color filter devices, which can be selectively moved into the beam path between the light source and the surface to be inspected. In this case, "radiating device" is understood to mean a light source having corresponding color filter devices.

[0055] Particularly preferably, the radiation device and / or equipment has a filter wheel that can rotate about a predetermined axis of rotation, and a filter or color filter device is arranged on the filter wheel.

[0056] Preferably, at least three color filter devices are provided, preferably at least four color filter devices, preferably at least five color filter devices, preferably at least six color filter devices, preferably at least eight color filter devices, preferably at least twelve color filter devices, preferably at least fifteen color filter devices, and preferably at least twenty color filter devices.

[0057] In another preferred embodiment, fewer than 50 filter devices are provided, preferably fewer than 40 color filter devices, and more preferably fewer than 30 color filter devices.

[0058] Preferably, all filter devices are located at the same distance from the axis of rotation of the filter wheel.

[0059] A drive mechanism, such as a drive motor, can be provided that can move individual filter devices in front of the light source and / or move individual filter devices into the beam path between the light source and the surface (by rotating the filter wheel). Preferably, the drive motor is an electric motor, and particularly a stepper motor. This can preferably move the filter wheel to multiple rotational positions.

[0060] Preferably, the housing is optically sealed so that no ambient light can enter the housing. In particular, the filter wheel is preferably designed such that the filter wheel forms an optically tight seal with the housing, so that even in the region of the beam path between the light source of the first radiating device and the filter wheel, no ambient light can enter the housing.

[0061] In known devices, multiple light-emitting diodes (LEDs) are provided, such as 26 LEDs, which are monochromatic or partially interference-filtered. It is now conceivable to provide only one light source or multiple similar light sources, particularly white light sources. These white light sources are especially preferably interference-filtered. This multiple filtering also allows for backward compatibility with older devices from the same applicant.

[0062] Using filters does have the disadvantage of significantly attenuating the light reaching the surface. However, the applicant was able to determine that the light sources available on the market today are powerful enough that, despite the filters, sufficient radiant power still reaches the surface.

[0063] A significant advantage is that a significantly fewer number of LEDs are required; for example, only one LED is needed now, instead of the 26 LEDs in the previous embodiment. This improves cost efficiency.

[0064] Another advantage of using a filter wheel is that the filter wheel does not need to be powered because it does not contain any electronic components.

[0065] On the other hand, as mentioned above, the light intensity can be lower than that of colored LEDs. Therefore, it has been proposed to provide special optics, particularly collimating optics, on white LEDs. In this way, the radiation can be concentrated.

[0066] Preferably, a camera or image recording device with achromatic camera optics is used. High-performance achromatic imaging optics can achieve uniform illumination and reduce chromatic aberration or spherical aberration.

[0067] In another preferred embodiment, the device has a radiation deflection device designed such that: on the one hand, radiation emitted by the first radiation device strikes a surface via a beam deflector, and on the other hand, radiation reflected from the surface strikes a further radiation detection device and / or is correspondingly deflected via the radiation deflection device.

[0068] Preferably, the radiation deflection device has a radiation separator. This radiation separator can and preferably is movable. At one position of the radiation separator, radiation emitted from the first radiation device can pass through the radiation deflection device unimpeded and is therefore preferably not deflected.

[0069] At the second position of the radiation separator, radiation reflected from the surface can be reflected at the radiation separator so that the radiation reaches another radiation detection device.

[0070] Preferably, at least one lens is disposed between the first radiating device and the radiating deflecting device. Particularly preferably, the lens is disposed between the radiating deflecting device and the surface to be inspected. Preferably, at least one of these lenses is achromatic, and more preferably, both lenses are achromatic. It is also conceivable and preferred that these two lenses form an achromatic objective lens.

[0071] In another preferred embodiment, the first angle at which the surface of the first radiating device irradiates is between 40° and 50° relative to the direction perpendicular to the surface, preferably between 42° and 48°, preferably between 43° and 47°, particularly preferably between 44° and 46°, and particularly preferably 45°.

[0072] In another advantageous embodiment, the device includes a third radiation detection device adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a third emission angle in response to irradiated radiation (particularly radiation irradiated by the first irradiation device).

[0073] In another advantageous embodiment, the device has a fourth radiation detection device adapted and designed to detect radiation emitted, and in particular scattered, from the surface to be inspected at a fourth emission angle in response to irradiation.

[0074] Preferably, none of the first to fourth radiation detection devices are arranged such that radiation reflected from the surface to be inspected (irradiated by the first radiation device) is detected.

[0075] Particularly preferably, a fifth radiation detection device is provided, which is adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a fifth emission angle in response to irradiation.

[0076] In another particularly preferred embodiment, a sixth radiation detection device is also provided, which is adapted and intended to detect radiation emitted, and in particular scattered, from the surface to be inspected at a sixth emission angle in response to irradiation.

[0077] In the latter case, the radiation irradiated onto the surface by the radiating device is observed from six different angles. This observation or detection of radiation allows for the acquisition of very accurate surface images and / or allows for the analysis of the surface's optical properties in a very precise manner.

[0078] Preferably, at least one of these radiation detection devices is adapted and designed to detect the intensity of the radiation impacting it. Preferably, at least two radiation detection devices, preferably at least three radiation detection devices, and particularly preferably all of these radiation detection devices are adapted and designed to detect the intensity of the radiation impacting them.

[0079] These radiation detection devices are adapted and designed to detect light (especially light intensity) at different wavelengths. In particular, these radiation detection devices are adapted to detect light at least throughout the entire visible spectrum.

[0080] Therefore, preferably, starting with the first radiating device, light of different colors or wavelengths is irradiated onto the surface by the filters described above, and the light scattered by the surface is detected by the four, five, or six radiation detection devices mentioned above.

[0081] In another advantageous embodiment, the device includes an image recording apparatus adapted and intended to record spatially resolved radiation emitted from the surface, particularly scattered radiation. Particularly preferably, the image recording apparatus is arranged vertically above the surface to be inspected.

[0082] Particularly preferably, the image recording device is focused onto the surface to be inspected and thus records an image of the surface illuminated by the control device. Preferably, the image recording device is adapted and designed to determine the light intensity occurring on the image recording device.

[0083] Preferably, the image recording device is a high-resolution image recording device, and particularly a color image camera. For example, the image recording device may have a 5-megapixel camera chip.

[0084] Particularly preferred is that the imaging system for projecting an image or the surface to be inspected onto the image recording device is designed such that the imaging system produces a uniformly illuminated image field with minimal deviation.

[0085] This image recording device is particularly preferably also suitable for and designed to record effect pigments that may be present on the surface to be inspected. The above procedure offers the advantage of integrating additional measurement methods in a particularly cost-effective manner, according to which an additional irradiation angle is provided for gloss measurement. This can be achieved, for example, by adding only a lens and a diode to the device.

[0086] In this way, gloss measurements with at least moderate accuracy can also be performed. This is particularly useful if additional information is provided to the customer to supplement color measurements.

[0087] In another preferred embodiment, the device has an additional radiation detector device adapted and designed to detect radiation emitted from the surface along the radiation direction, and preferably emits at least one signal representing the characteristics of the radiation. Preferably, the additional radiation detection device and the additional radiation detector device are spatially separated from each other, and particularly separated from each other within a housing. Particularly preferably, the aforementioned radiation deflection device is arranged between the radiation detection device and the additional radiation detector device.

[0088] In another preferred embodiment, the radiation deflection device can direct radiation to both another radiation detection device and another radiation detector device.

[0089] In another preferred embodiment, the radiation detector device is positioned relative to the radiation deflection device of another radiation detection device.

[0090] In another preferred embodiment, the additional radiation detector device is also adapted and designed to detect additional radiation components reflected and / or scattered by the surface.

[0091] In another preferred embodiment, an additional radiation detector device is adapted and intended to output a signal related to the intensity of the radiation impacting it.

[0092] In another preferred embodiment, an additional radiation detector device is arranged within the housing at substantially the same height as the additional radiation detection device.

[0093] The present invention also relates to a radiation deflection device, particularly for devices of the type described above. The radiation deflection device has a housing and a first radiation inlet, through which radiation can enter the housing in a first irradiation direction. Furthermore, the radiation deflection device has a first radiation outlet, through which radiation entering through the first radiation inlet can exit the housing in the irradiation direction.

[0094] According to the invention, a radiation separator device or radiation separator is arranged in a housing, which is adapted and intended to deflect radiation entering through a radiation outlet in a direction opposite to the irradiation direction along a deflection direction that deviates from and is opposite to the irradiation direction, and is particularly perpendicular to the irradiation direction. Furthermore, the housing also has a second radiation outlet through which the radiation deflected by the radiation separator device can exit the housing.

[0095] Therefore, a radiation deflection device was proposed, in which radiation can simultaneously enter and be deflected through the radiation outlet.

[0096] The radiation separator device is particularly preferably a glass element, and especially a thin glass element. The thickness of this thin glass element is particularly preferably greater than 0.1 mm, preferably greater than 0.2 mm, and preferably greater than 0.3 mm. Particularly preferably, the thickness of the thin glass element is less than 2.0 mm, preferably less than 1.5 mm, preferably less than 1.0 mm, preferably less than 0.8 mm, particularly preferably less than 0.6 mm, and particularly preferably less than 0.4 mm.

[0097] Preferably, the radiation separator device is highly transparent over a wide wavelength range (i.e., the (pure) transmittance of the radiation separator device is preferably greater than 90%, preferably greater than 95%, and particularly preferably greater than 98%).

[0098] Preferably, the radiation separator device is arranged in a fixed position, particularly at a fixed angle relative to the incident radiation. Preferably, this angle is between 30° and 60°, more preferably between 35° and 55°, more preferably between 40° and 50°, and particularly preferably about 45°.

[0099] This radiation separator device preferably divides all light rays into transmitted and reflected portions, regardless of whether the light rays strike its front or rear surface. The type of division is determined according to Fresnel's equations, which depend on the refractive index and the angle of incidence.

[0100] In the application described herein, there are therefore preferably a total of two transmission paths and two reflection paths. The transmitted radiation (preferably the majority) undergoes parallel radiation deflection as it passes through the radiation separator.

[0101] As mentioned above, the radiation deflection device described herein enables radiation emitted from a first radiation device onto a surface to be deflected in the opposite direction, particularly to another radiation detection device.

[0102] In a preferred embodiment, at least one optical element, particularly a lens, is integrated into the first radiation input of the radiation deflection device.

[0103] Preferably, at least one optical element, particularly a lens, is also integrated into the first radiation output terminal.

[0104] In another advantageous embodiment, the radiation deflection device can be integrally integrated into the housing.

[0105] The radiation separator device is preferably a mirror, and particularly a pivotable mirror. The mirror is preferably pivotable about an axis perpendicular to the irradiation direction. Preferably, the mirror can be pivoted between 20° and 90°, more preferably between 30° and 70°, and particularly preferably between 40° and 50°.

[0106] In another preferred embodiment, the radiation deflection device includes a third outlet through which the deflected radiation can be emitted.

[0107] Particularly preferably, the third outlet is spaced apart from the second and first outlets. Particularly preferably, the third outlet is positioned opposite to the second outlet. Particularly preferably, the radiation separator device is arranged between the second and third outlets.

[0108] Furthermore, the radiation separator device is preferably adapted to direct radiation toward the second output end and to direct radiation toward the third output end.

[0109] In another preferred embodiment, the radiation emitted from the second output terminal is in the opposite direction and parallel to the radiation emitted from the third output terminal.

[0110] The present invention also relates to a method for inspecting the optical properties of a surface, wherein a first radiating device irradiates radiation onto the surface to be inspected along a first irradiation direction, the first irradiation direction being characterized by a first irradiation angle, and a first radiation detection device and / or a radiation detector device detects radiation emitted from and, in particular, scattered from the surface to be inspected at a first emission angle in response to the irradiated radiation.

[0111] In addition, the second radiation detection device detects radiation emitted from the surface to be inspected at a second emission angle in response to irradiation, and in particular, scattered radiation.

[0112] According to the invention, the second radiating device of the apparatus emits radiation onto the surface to be inspected along a second irradiation direction, the second irradiation direction being predetermined by a second irradiation angle, wherein the first irradiation angle and the second irradiation angle are substantially opposite to each other with respect to a direction perpendicular to the surface to be inspected (particularly a direction that also intersects the surface to be inspected) and / or a plane.

[0113] Therefore, in this method, it is also proposed that, on the one hand, light is irradiated onto the surface in a specific direction, but on the other hand, radiation reflected from the surface in the opposite direction is also detected.

[0114] In another method according to the invention for inspecting the optical properties of a surface, a first irradiation device irradiates radiation onto the surface to be inspected along a first irradiation direction characterized by a first irradiation angle, a first radiation detection device detects radiation emitted from the surface to be inspected at a first emission angle in response to the irradiated radiation, and particularly scattered radiation, and a second radiation detection device detects radiation emitted from the surface to be inspected at a second emission angle in response to the irradiated radiation, and particularly scattered radiation.

[0115] According to the invention, the device includes an additional radiation detection device that detects radiation emitted and, in particular, reflected from the surface to be inspected in response to incident radiation along an emission direction, the emission direction being characterized by an additional emission angle, wherein the irradiation direction and the emission direction are substantially opposite.

[0116] Preferably, the surface examined using this method is designed such that it reflects a large portion of the radiation incident upon it in a direction opposite to the irradiation direction (in particular, the surface reflects a large portion of the radiation incident upon it regardless of the irradiation angle).

[0117] Particularly preferably, the surface is a surface containing reflective particles and / or reflective pigments.

[0118] Radiation reflected from the surface is initially reflected along the direction of the first radiating device, but preferably does not reach that device; instead, it is deflected by a predetermined angle (particularly by the aforementioned radiation separator device). Advantageously, this angle is between 30° and 150°, preferably between 60° and 120°, preferably between 70° and 110°, preferably between 80° and 100°, and particularly preferably between 85° and 95°.

[0119] Particularly preferably, radiation is irradiated onto the surface by a first irradiation device, and the radiation is reflected at different times in a direction opposite to the first irradiation direction.

[0120] In another preferred method, the surface to be inspected is irradiated (particularly by a first radiating device) with light of different wavelengths and / or different colors.

[0121] The filter arrangement is particularly preferred for the purpose of irradiating with different colors, wherein different color filters (one after another) are placed in the radiation path between the irradiation device and the surface.

[0122] A filter wheel carrying multiple filter elements is preferably used to irradiate the surface to be inspected with different colors. The multiple filter elements can be selectively placed in the beam path between the irradiation device and the surface or moved in the beam path between the irradiation device and the surface.

[0123] In another preferred method, at least one spatially resolved image of the surface irradiated by the first radiating device is recorded. Preferably, at least one image of the surface irradiated by the second radiating device is recorded.

[0124] Particularly preferably, the spatially resolved image is recorded at an angle of 90° relative to the surface.

[0125] The present invention also relates to the use of devices of the type described above and / or methods of the type described above for inspecting the optical surface properties of retroreflective surfaces.

[0126] "Retroreflective surface" is understood to mean, in particular, those surfaces that reflect a large portion of the radiation incident on them in a direction opposite to the irradiation direction, and in particular, those surfaces that reflect a large portion of the radiation regardless of the irradiation direction (in particular, the irradiation direction deviates from the irradiation direction perpendicular to the surface by at least 10°, preferably at least 20°, preferably at least 30°).

[0127] "A large portion" is understood to mean that the large portion is much larger than the portion of radiation scattered along that direction, that is, (in terms of intensity) at least twice as large, preferably at least three times as large, preferably at least five times as large, and preferably at least ten times as large. Attached Figure Description

[0128] Further advantages and embodiments will become apparent from the accompanying drawings. In the drawings: Figure 1 A schematic representation of the device according to the invention is shown; Figure 2 Showing Figure 1 The part is indicated to show the angle; Figure 3 The diagram shows a representation of the filter wheel of the device according to the invention; Figure 4 A representation of a radiation deflection device according to the present invention is shown; and Figure 5 Further embodiments of the invention for use with retroreflective surfaces are shown. Detailed Implementation

[0129] Figure 1 The diagram shows a device 1 according to the invention, which is used to inspect the optical properties of a surface 10. The device 1 has a first radiating device 2 that radiates, in particular, light onto the surface 10 along a first irradiation direction R1.

[0130] Reference numeral 12 indicates a first radiation detection device that detects radiation scattered from surface 10 at a first emission angle b1 in response to irradiation.

[0131] Reference numeral 14 indicates a second radiation detection device that detects radiation scattered from surface 10 at a second emission angle b2 in response to irradiation.

[0132] Reference numeral 16 in the figure indicates a third radiation detection device that detects radiation scattered from surface 10 at a third emission angle b3 in response to irradiation.

[0133] Reference numeral 17 indicates a fourth radiation detection device that detects radiation scattered from surface 10 at a fourth emission angle in response to irradiation.

[0134] Reference numeral 18 in the attached figure indicates a fifth radiation detection device, which detects radiation scattered from surface 10 at a fifth emission angle in response to irradiation.

[0135] In addition, a sixth radiation detection device is provided, which detects radiation scattered from surface 10 at a sixth scattering angle in response to irradiation.

[0136] Preferably, the sixth radiation detection device is arranged vertically above the surface to be inspected. Preferably, the sixth radiation detection device is also adapted and intended to record a spatially resolved image of the radiation incident upon it.

[0137] Reference numeral 4 in the attached figure indicates a second radiating device that irradiates the surface 10 along a second irradiation direction R2. The surface reflects the radiation in a direction opposite to the first irradiation direction, and thus reflects the radiation along the direction of the first irradiating device 2.

[0138] Reference numeral 20 indicates the housing, in which various radiation detection devices and radiation devices are arranged.

[0139] Reference numeral 30 indicates a filter wheel, which carries multiple color filters that can be selectively inserted into the radiation path between the first radiation device 2 and the surface.

[0140] Figure 2 Shown in Figure 1 A partial view of the device displayed in the image. Figure 2 The irradiation angle a1 is shown, which represents the irradiation direction R1. The first irradiation device 2 irradiates the surface 10 along the irradiation direction R1.

[0141] Furthermore, a first radiation angle b1 and a second radiation angle b2 are shown, under which the first radiation detection device and the second radiation detection device detect scattered radiation from surface 10. For clarity, other radiation angles are not shown. The dashed line indicates the second irradiation direction R2, under which the second irradiation direction 4 (see...) Figure 1 Radiation is irradiated onto surface 10.

[0142] Figure 3A filter wheel 30 is shown, which is used to illuminate or irradiate a surface with different colors. The filter wheel has multiple color filters 32, 34, and 36, which can be pushed (or rotated) into the beam path between the first irradiation device 2 and the surface.

[0143] Figure 4 A detailed view of the device according to the invention is shown. Reference numeral 40 denotes a radiation deflection device. The radiation deflection device has a housing 42. Reference numeral 44 indicates a radiation inlet through which radiation can enter the housing in the direction R1.

[0144] Reference numeral 46 indicates the radiation outlet, through which radiation irradiated along the radiation direction R1 can exit from the housing 42.

[0145] However, the radiation output terminal 46 is also used as a radiation input terminal for radiation reflected from the surface 10.

[0146] Radiation separator 48 directs the radiation entering through the radiation output terminal toward the second radiation output terminal 52, thereby directing the radiation to another radiation detection device (shown schematically only).

[0147] Figure 5 Another embodiment of the device according to the invention is shown, which is particularly used for inspecting retroreflective surfaces. When the irradiation direction is arbitrary and, in particular, not perpendicular to the surface, the retroreflective surface reflects light, typically radiation, in a direction opposite to the irradiation direction.

[0148] therefore, Figure 5 Showing with Figure 4 The design shown is similar to the one in the diagram. For the design of the first radiating device and the filter wheel, please refer to the description above.

[0149] The radiation device emits radiation along direction R1 through opening 23 in the housing onto a surface not shown. Radiation reflected from this surface along direction R1', opposite to direction R1, is deflected by 90° and reaches another radiation detection device 15.

[0150] The additional radiation detection device 15 can detect at least one characteristic property of radiation reflected along direction R1', such as intensity. However, the additional radiation detection device can also record a spatially resolved image of the radiation impacting the additional radiation detection device, and / or the additional radiation detection device can also be adapted and intended for this purpose.

[0151] Reference numeral 19 indicates a control device, which in particular also controls the first radiating device and a further radiation detection device. Preferably, the control is performed such that the further radiation detection device receives radiation emitted by the first radiating device along the radiation direction R1 and reflected by the surface in the opposite direction.

[0152] exist Figure 5 The arrows shown indicate several directions of radiation scattered from the surface that can be detected by a radiation detection device, as described above.

[0153] exist Figure 5 In the illustration shown, radiation scattered from the surface can be advantageously detected in six or seven different directions.

[0154] Reference numeral 21 indicates an additional radiation detector device or additional radiation detection device, which is also adapted and intended to receive radiation emitted from the surface along direction R1', and preferably output at least one signal characteristic of the radiation. This additional device 21 may preferably be used for reference.

[0155] The applicant reserves the right to claim all features essential to the invention disclosed in the application documents, provided that all features, individually or in combination, are novel compared to the prior art. It should also be noted that individual figures also depict features that may be advantageous in themselves. Those skilled in the art will readily recognize that the specific features described in the figures can be advantageous even without employing other features from the figures. Furthermore, those skilled in the art will recognize that advantages can also arise from combinations of several features shown in individual figures or different figures.

Claims

1. An apparatus (1) for inspecting the optical properties of a surface, comprising: a first radiating device (2) adapted and intended to irradiate radiation onto a surface to be inspected along a first irradiation direction (R1), the first irradiation direction being characterized by a first irradiation angle (a1); a first radiation detection device (12) adapted and intended to detect radiation emitted from the surface to be inspected (10) at a first emission angle (b1) in response to the irradiated radiation; and a second radiation detection device (14) adapted and intended to detect radiation emitted from the surface to be inspected (10) at a second emission angle (b2) in response to the irradiated radiation. Its features are, The device (1) has an additional radiation detection device (15) adapted and designed to detect radiation emitted and, in particular, reflected by the surface to be inspected (10) at a different emission angle (R1') in response to the irradiation, wherein the irradiation direction (R1) and the emission direction (R1') are substantially opposite to each other, and / or The device (1) has a second radiation device (4) adapted and intended to irradiate the surface to be inspected along a second irradiation direction (R2), the second irradiation direction being characterized by a second irradiation angle (a2), wherein the first irradiation angle (a1) and the second irradiation angle (a2) are substantially opposite to each other with respect to the direction perpendicular to the surface to be inspected.

2. The device (1) according to claim 1, characterized in that, The device (1) includes a control device that causes radiation emitted by the first radiation device to strike the surface and causes radiation emitted by the surface in response to the incident radiation to strike the additional radiation detection device.

3. The device (1) according to claim 1 or 2, characterized in that, The second radiation device is positioned such that radiation emitted by the second radiation device (4) is reflected by the surface to be inspected in a direction opposite to the first irradiation direction (R1).

4. The device (1) according to at least one of the preceding claims, characterized in that, The device has an additional detection device (22) adapted and designed to detect radiation emitted by the second radiation device (4) and reflected by the surface.

5. The device (1) according to at least one of the preceding claims, characterized in that, The device has a housing (20) in which the first radiation device (2), the first radiation detection device (12), the second radiation detection device (14) and the additional radiation detection device are arranged, wherein the housing has an opening through which the first radiation device irradiates the surface (10) to be inspected.

6. The device (1) according to at least one of the preceding claims, characterized in that, The first radiation device is adapted and intended to emit radiation in different colors, wherein the first radiation device preferably has a light source and a plurality of color filter devices that can be selectively moved into the beam path between the light source and the surface to be inspected, wherein the radiation device preferably has a filter wheel that can rotate about a predetermined axis of rotation, and the color filter devices are arranged on the filter wheel.

7. The device (1) according to at least one of the preceding claims, characterized in that, The device (1) has a radiation deflection device (40) which is designed and arranged such that radiation emitted from the first radiation device is directed by the radiation deflection device (40) onto the surface (10), and radiation reflected from the surface is directed by the radiation deflection device to another detector device or the other radiation detection device, wherein the radiation deflection device preferably includes a radiation separator.

8. The device (1) according to at least one of the preceding claims, characterized in that, The first angle (a1) is between 40° and 50° relative to the direction perpendicular to the surface, preferably between 42° and 48°, preferably between 43° and 47°, particularly preferably between 44° and 46°, and particularly preferably 45°.

9. The device (1) according to at least one of the preceding claims, characterized in that, The device has a third radiation detection device (16) adapted and intended to detect radiation emitted from the surface to be inspected (10) at a third emission angle (b3) in response to the irradiation, and in particular the device has a fourth radiation detection device (16) adapted and intended to detect radiation emitted from the surface to be inspected (10) at a fourth emission angle (b4) in response to the irradiation, and in particular scattered radiation.

10. The device (1) according to at least one of the preceding claims, characterized in that, The device (1) has an image recording device adapted and intended to detect radiation emitted and, in particular, scattered by the surface (10) in a spatially resolved manner, wherein the image recording device is preferably arranged vertically above the surface to be inspected.

11. The device (1) according to at least one of the preceding claims, characterized in that, The device (1) has an additional radiation detector device (..), which is adapted and intended to detect radiation emitted from the surface along the emission direction (R1'), and preferably emits at least one signal representing the characteristics of the radiation.

12. A radiation deflection device (40) comprising: a housing (42); a radiation inlet (44) through which radiation can enter the housing along a first irradiation direction (R1); and a first radiation outlet (46) through which radiation entering through the radiation inlet (44) exits the housing along the irradiation direction. Its features are, A radiation separator device (48) is arranged in the housing (42) and is adapted and intended to deflect radiation passing through the radiation outlet (46) in a deflection direction (Q) in a direction opposite to the irradiation direction (R1) and in a direction opposite to the irradiation direction, and particularly perpendicular to the irradiation direction. The housing (42) also has a second radiation outlet (52) through which the radiation deflected by the radiation separator device can exit the housing (42).

13. A method (1) for inspecting the optical properties of a surface, wherein, A first radiation device (2) irradiates the surface to be inspected along a first irradiation direction (R1), characterized by a first irradiation angle (a1). A first radiation detection device (12) detects radiation emitted from the surface to be inspected (10) at a first emission angle (b1) in response to the irradiated radiation, and in particular, scattered radiation. A second radiation detection device (14) detects radiation emitted from the surface to be inspected (10) at a second emission angle (b2) in response to the irradiated radiation, and in particular, scattered radiation. Its features are, The device (1) has an additional radiation detection device that detects radiation emitted, and in particular reflected, by the surface to be inspected (10) at a different emission angle (R1') in response to the irradiation, wherein the irradiation direction (R1) and the emission direction (R1') are substantially opposite, and / or The second radiation device (4) of the device irradiates the surface to be inspected along a second irradiation direction (R2), the second irradiation direction being characterized by a second irradiation angle (a2), wherein the first irradiation angle (a1) and the second irradiation angle (a2) are substantially opposite to each other about the direction perpendicular to the surface to be inspected.

14. The method according to the preceding claims, characterized in that, The first radiating device specifically irradiates the surface continuously with light of different wavelengths.

15. Use of the device according to at least one of the preceding claims, and / or use of the method according to at least one of the preceding claims, the use being for inspecting the optical surface properties of a retroreflective surface.

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