A detection device and method for internal cracks of multilayer film optical elements

Abstract

The present invention relates to the field of optical detection, and discloses a detection device and a detection method for internal cracks of a multilayer film optical element. The device includes a detection base with a hollow structure and a one-to-one corresponding image acquisition device and a light source. The hollow structure is used to expose the multilayer film optical element; the corresponding image acquisition device and the light source are respectively arranged on both sides of the plane where the detection base is located; the area where the light source irradiates the multilayer film optical element covers the imaging area of ​​the corresponding image acquisition device on the multilayer film optical element, and the image acquisition device is configured to be triggered to capture an image under the premise that the corresponding light source is lit; the part of the multilayer film optical element located at the hollow structure is divided into one or more areas, each area is captured by a plurality of images by the image acquisition device, and the corresponding imaging angles of the plurality of images captured in the same area are different. By using a common imaging sensor for multi-directional imaging, the fine cracks inside the film can be accurately identified.

Description

Technical Field

[0001] The present invention relates to the field of optical sample crack detection, and in particular to a detection device and a detection method for internal cracks of a multilayer film optical element. Background Art

[0002] Multilayer optical components are prone to internal cracks, and these cracks are subtle in features, with widths usually in the micrometer range.

[0003] In addition, optical components are prone to reflect light. Therefore, if a camera is used to capture images to identify cracks inside multi-layer film optical components, very high requirements are placed on the precision of the camera. Such cameras are very expensive and may not necessarily achieve imaging effects that meet the requirements for detection and identification.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present application. It does not necessarily belong to the prior art of the present application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of the present application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] The purpose of the present invention is to provide a detection device and method for internal cracks of a multi-layer film optical element, by shooting the same area of ​​the multi-layer film optical element with multiple cameras, ensuring that at least one of the cameras can capture an image with crack characteristics due to light passing through the cracks.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A detection device for internal cracks of a multilayer film optical element, comprising at least one image acquisition device, at least one light source and a detection base with a hollow structure, wherein the hollow structure of the detection base matches the multilayer film optical element to be detected, and the wavelength of the light source is within the channel wavelength range of the multilayer film optical element;

[0008] The image acquisition devices correspond to the light sources one by one, and the corresponding image acquisition devices and light sources are respectively arranged on both sides of the plane where the detection base is located, and the angle between the imaging optical axis of the image acquisition device and the projection axis of the light beam optical axis of the corresponding light source on the plane where the detection base is located is between 0° and 45°;

[0009] The area where the light source irradiates the multilayer film optical element covers the imaging area of ​​the multilayer film optical element by the corresponding image acquisition device, and the image acquisition device is configured to be triggered to capture an image under the premise that the corresponding light source is lit;

[0010] The at least one image acquisition device is configured to meet the following conditions: the portion of the multilayer film optical element located at the hollow structure is divided into one or more target imaging areas, each target imaging area is captured with multiple images by the image acquisition device, and the corresponding imaging angles of the multiple images captured for the same target imaging area are different.

[0011] Furthermore, based on any one of the technical solutions or a combination of multiple technical solutions described above, the detection device provided by the present invention also includes a processor, which is configured to identify whether there are crack features in all images captured of all areas on the multilayer film optical element. If not, the processor determines that the multilayer film optical element to be detected does not have a crack defect, otherwise, it determines that the multilayer film optical element has a crack defect.

[0012] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 10° and 80°;

[0013] The angle between the optical axis of the light beam of each light source and the plane where the detection base is located is between 10° and 80°.

[0014] Furthermore, based on any one of the technical solutions or a combination of multiple technical solutions described above, there is a first angle between the imaging optical axis of the image acquisition device and the plane where the detection base is located, and there is a second angle between the light beam optical axis of the corresponding light source and the plane where the detection base is located, and the difference between the first angle and the second angle is between -30° and 30°.

[0015] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 40° and 50°;

[0016] The angle between the optical axis of the light beam of each light source and the plane where the detection base is located is between 40° and 50°.

[0017] Furthermore, based on any one of the technical solutions or a combination of multiple technical solutions described above, the imaging optical axis of the image acquisition device is coplanar with the optical axis of the light beam of the corresponding light source, and the plane where the detection base is located is located on the angular bisector plane between the imaging optical axis of the image acquisition device and the optical axis of the light beam of the corresponding light source.

[0018] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the number of the image acquisition devices is multiple, and the imaging area of ​​the multi-layer film optical element by each image acquisition device covers the entire area of ​​the multi-layer film optical element located at the hollow structure;

[0019] The angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is greater than 0° and less than or equal to 60°.

[0020] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is less than 55°;

[0021] And / or, all the image acquisition devices are located on the same side of a virtual plane perpendicular to the detection base.

[0022] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the number of the image acquisition device is one, and the imaging area of ​​the multi-layer film optical element by the image acquisition device covers the entire area of ​​the multi-layer film optical element located at the hollow structure;

[0023] The detection device also includes a driving device, which is configured to drive the detection base to rotate within the plane where it is located, or to synchronously drive the image acquisition device and its corresponding light source to rotate.

[0024] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, the detection base is configured to rotate around its own center, and the angle of a single rotation does not exceed 60°;

[0025] And / or, the detection base is configured to rotate unidirectionally clockwise or counterclockwise around its own center, and the sum of angles of multiple rotations does not exceed 180°.

[0026] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, the image acquisition device is configured to rotate around a virtual vertical line perpendicular to the detection base, and the angle of a single rotation does not exceed 60°, wherein the virtual vertical line intersects or is adjacent to the imaging optical axis of the image acquisition device;

[0027] And / or, the image acquisition device is configured to rotate unidirectionally clockwise or counterclockwise around a virtual vertical line perpendicular to the detection base, and the sum of the angles of multiple rotations does not exceed 180°, wherein the virtual vertical line intersects or is adjacent to the imaging optical axis of the image acquisition device.

[0028] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the imaging area of ​​the multi-layer film optical element by the image acquisition device is smaller than the entire area of ​​the multi-layer film optical element located at the hollow structure;

[0029] The detection device also includes a driving device, which is configured to drive the detection base to rotate and / or translate within the plane where it is located, or to synchronously drive the image acquisition device and its corresponding light source to rotate and / or translate.

[0030] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the number of the image acquisition devices is multiple, and the installation orientations of the multiple image acquisition devices make their imaging areas of the multi-layer film optical element at least partially overlap, and the driving device is configured to drive the detection base to translate, or synchronously drive the image acquisition device and its corresponding light source to translate;

[0031] Alternatively, there are multiple image acquisition devices, and the installation positions of the multiple image acquisition devices make them adjacent to the imaging areas of the multilayer film optical element, and the driving device is configured to synchronously drive the image acquisition devices and their corresponding light sources to rotate;

[0032] Alternatively, the number of the image acquisition device is one, and the driving device is configured to drive the detection base to perform rotational and translational movements, or to synchronously drive the image acquisition device and its corresponding light source to perform rotational and translational movements.

[0033] According to another aspect of the present invention, the present invention provides a method for detecting internal cracks of a multilayer film optical element, comprising:

[0034] Acquire a passband wavelength range of a multilayer film optical element to be detected, and select at least one light source within the passband wavelength range;

[0035] The multi-layer film optical element to be detected is suspended on a detection base with a hollow structure;

[0036] At least one image acquisition device is arranged on one side of the plane where the detection base is located, and at least one light source is arranged on the other side thereof, the image acquisition device corresponds to the light source one by one, and the area irradiated by the light source on the multilayer film optical element covers the imaging area of ​​the multilayer film optical element by the corresponding image acquisition device;

[0037] Lighting up the light source and triggering its corresponding image acquisition device to capture an image of a preset target imaging area; repeating this step at different imaging angles for the same target imaging area to obtain multiple images;

[0038] Identify whether all captured images have crack features. If not, determine that the multilayer film optical element does not have a crack defect in the target imaging area. Otherwise, determine that the multilayer film optical element has a crack defect in the target imaging area.

[0039] The beneficial effects brought by the technical solution provided by the present invention are as follows:

[0040] a. Using multiple common image acquisition devices, such as CMOS or CCD sensors, to image the target imaging area on the multi-layer film optical element from multiple angles, it is possible to accurately identify whether there are fine cracks inside the multi-layer film optical element;

[0041] b. Using a single CMOS or CCD sensor, without the need for expensive high-precision cameras, combined with a drive device, it is also possible to image the target imaging area from multiple angles, and accurately identify whether there are fine cracks inside multi-layer film optical components. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic structural diagram of a detection device for multi-camera shooting provided by an exemplary embodiment of the present invention;

[0044] Figure 2 A schematic structural diagram of a detection device for single-camera shooting provided by an exemplary embodiment of the present invention;

[0045] Figure 3 A schematic flow chart of a method for detecting internal cracks in a multilayer film optical element provided by an exemplary embodiment of the present invention;

[0046] Figure 4 for Figure 1 Schematic diagram of the distribution of the projections of the imaging optical axes of the four image acquisition devices on the plane. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0049] In one embodiment of the present invention, a device for detecting internal cracks in a multilayer film optical element is provided. Figure 1 and Figure 2 The detection device includes at least one image acquisition device, at least one light source and a detection base with a hollow structure, wherein the hollow structure of the detection base matches the multilayer film optical element 100 to be detected, and the hollow structure is used to not block the main part of the multilayer film optical element, so that the light source can illuminate the upper surface / lower surface of the multilayer film optical element, and the image acquisition device can capture the image of the lower surface or upper surface of the multilayer film optical element.

[0050] One implementation of the detection base is to support the edge portion of a multilayer film optical element with a planar structure. Since cracks in the central area of ​​the optical element will seriously affect the optical performance of the element, while cracks in the peripheral area will have a relatively small impact on the performance. Therefore, the central area is the main detection area, and the edge portion blocked by the detection base is ignored as the area for detection. Another implementation is that the detection base uses vacuum adsorption to adsorb the edge portion of the upper surface of the multilayer film optical element.

[0051] The image acquisition device corresponds to the light source one by one, such as Figure 1 As shown, the detection device is provided with a first image acquisition device 210, a second image acquisition device 220, a third image acquisition device 230 and a fourth image acquisition device 240, and a first light source 310, a second light source 320, a third light source 330 and a fourth light source 340 are provided correspondingly, and the corresponding image acquisition devices and light sources are respectively arranged on both sides of the plane where the detection base is located, except as shown Figure 1 In addition to the four image acquisition devices shown in the figure being arranged above the detection base, and the four light sources being arranged below the detection base, in other embodiments, some of the image acquisition devices may be arranged below, and their corresponding light sources may be arranged above, for example, Figure 1The technical solution of the present invention can also be implemented by exchanging the upper and lower positions of the first image acquisition device 210 and the first light source 310.

[0052] The side views of each pair of corresponding image acquisition devices and light sources can be seen in Figure 2 The angle between the imaging optical axis of the image acquisition device 200 and the corresponding light beam optical axis of the light source 300 on the plane where the detection base is located (i.e., the plane where the multilayer film optical element 100 is located) is between 0° and 45°. In a specific embodiment, the imaging optical axis of the image acquisition device and the corresponding light beam optical axis of the light source are coplanar, that is, the projections of the two coincide (the angle is 0°); in a more specific embodiment, Figure 2 As shown, the plane where the detection base is located is located on the angular bisector plane between the imaging optical axis of the image acquisition device 200 and the optical axis of the light beam of the corresponding light source 300 .

[0053] The area where the light source 300 irradiates the multilayer film optical element 100 covers the imaging area of ​​the multilayer film optical element 100 by the corresponding image acquisition device 200, and the image acquisition device 200 is configured to be triggered to capture an image under the premise that the corresponding light source 300 is lit;

[0054] The at least one image acquisition device is configured to meet the following conditions: the portion of the multilayer film optical element located at the hollow structure is divided into one or more target imaging areas, each target imaging area is captured with multiple images by the image acquisition device, and the corresponding imaging angles of the multiple images captured for the same target imaging area are different.

[0055] The detection principle of fine cracks in the multilayer film provided in this embodiment is as follows: the defect is extremely fine, and typically, its width is in the micron level. Such fine cracks have extremely strict selectivity for light, requiring the light to be incident vertically or at least nearly vertically (with a deviation of 10° to 30° relative to the vertical direction, it is nearly vertical) in the direction of the fine crack, so that the light can pass through the crack and be clearly displayed in the imaging; on the contrary, if the incident light does not meet the selectivity requirements, the light incident on the lower surface of the crack cannot pass through, but is reflected on the lower surface, and the light cannot enter the camera lens above, so the key defect feature information will be lost in the imaging. Based on this, this embodiment proposes a multi-imaging angle imaging detection of multilayer film optical elements, where the multi-imaging angles must ensure that the existing defects can be displayed in the image formed at at least one of the angles; if the final imaging does not show the crack characteristics, it proves that the multilayer film optical element does not have crack defects.

[0056] Therefore, when selecting a light source, it is necessary to consider whether its wavelength is within the channel wavelength range of the multilayer film optical element; optionally, the specific wavelength of the light source is selected to satisfy that the transmittance of its light beam to the multilayer film optical element is greater than or equal to 40%, optionally, the transmittance of the light source to the multilayer film optical element is greater than or equal to 55%, and the wavelength of the light source with a transmittance greater than 80% is more preferred.

[0057] With the development of precision optics, transmissive multilayer film optical elements have been increasingly used in industrial production. The method for identifying internal cracks in multilayer film optical elements proposed in the embodiment of the present invention is applicable to multilayer film optical elements with transmissive properties, and is independent of the specific structure (such as the number or material or distribution of film layers, the processing technology of the multilayer film optical element) and size of the multilayer film optical element.

[0058] In one embodiment of the present invention, the detection device also includes a processor, which is configured to identify whether there are crack features in all images captured of all areas on the multilayer film optical element. If not, the processor determines that the multilayer film optical element to be detected does not have a crack defect; otherwise, it determines that the multilayer film optical element has a crack defect.

[0059] It should be noted that, in addition to the processor, all captured images may also be observed by human eyes to see whether there are crack features, and the technical solution of the present invention may also be implemented.

[0060] Optionally, the first angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 10° and 80°, the second angle between the optical axis of the light beam of each light source and the plane where the detection base is located is between 10° and 80°; the difference between the first angle and the second angle is between -30° and 30°. In a specific embodiment, Figure 2 As shown, the angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 40° and 50°; the angle between the light beam optical axis of each light source and the plane where the detection base is located is between 40° and 50°. In this case, the difference between the first angle and the second angle is between -10° and 10°.

[0061] First embodiment

[0062] like Figure 1 As shown, the number of the image acquisition devices is multiple. This embodiment takes four image acquisition devices and four light sources as an example. The imaging area of ​​the multilayer film optical element by each image acquisition device covers the entire area of ​​the multilayer film optical element located at the hollow structure;

[0063] All image acquisition devices are located on the same side of a virtual plane perpendicular to the detection base, corresponding to Figure 4 The maximum angle between the projection axes of the imaging optical axes of each image acquisition device on the plane where the detection base is located in the clockwise direction is less than 180°, and the angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is greater than 0° and less than or equal to 60°, preferably as follows Figure 4 Multiple image acquisition devices are distributed at equal angular intervals.

[0064] The present invention does not exclude the embodiment in which the maximum angle between the projection axis of the imaging optical axis of each image acquisition device on the plane where the detection base is located in the clockwise direction reaches 180° or even 360°, but within a half circle close to 180°, and the angle of a single rotation does not exceed 60°, it will basically not cause the leakage of detection of fine cracks, especially the single rotation angle is further reduced to 45° or even 30°, and it is not necessary to rotate a full circle after half a circle, so that if there is a crack, at least one rotation angle is perpendicular to the crack so that light passes through the crack and the image shows the crack feature. Adding an image acquisition device to increase the maximum angle will only increase the cost meaninglessly, but it can also achieve the technical solution of the present invention.

[0065] Second embodiment

[0066] Different from the first embodiment, the number of image acquisition devices and light sources is five or more than six, and accordingly, the angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is less than 55°.

[0067] Third embodiment

[0068] Different from the second embodiment, more image acquisition devices and light sources are provided, and the image acquisition devices are not limited to be located on the same side of a virtual plane perpendicular to the detection base, that is, they can be arranged circumferentially above the detection base.

[0069] Fourth embodiment

[0070] The number of the image acquisition device is one, and the imaging area of ​​the multilayer film optical element by the image acquisition device covers the entire area of ​​the multilayer film optical element located at the hollow structure;

[0071] The detection device also includes a driving device, which is configured to drive the detection base to rotate within the plane where it is located. Specifically, it can rotate around its own center, and the angle of a single rotation does not exceed 60°, preferably does not exceed 45°, and it rotates in a clockwise or counterclockwise direction, and the sum of the angles of multiple rotations is close to 180°. Obviously, the present invention does not exclude an embodiment in which the sum of the angles of multiple rotations reaches 360°, but within a half circle close to 180°, and the angle of a single rotation does not exceed 60°, it will basically not cause the leakage of fine cracks, especially when the single rotation angle is further reduced to 45° or even 30°, and it is ensured that if there is a crack, at least one rotation angle is perpendicular to the crack so that light passes through the crack and the imaging shows the crack characteristics.

[0072] Fifth embodiment

[0073] Different from the fourth embodiment, the driving device synchronously drives the image acquisition device and its corresponding light source to rotate. Specifically, the image acquisition device is configured to rotate around a virtual vertical line perpendicular to the detection base, and the angle of a single rotation does not exceed 60°, wherein the virtual vertical line intersects or is adjacent to the imaging optical axis of the image acquisition device (for example, the minimum distance between the two axes is less than 1 cm); and the sum of the angles of multiple rotations of clockwise or counterclockwise unidirectional rotation around the virtual vertical line is close to 180°. Similarly, the present invention does not exclude embodiments in which the sum of the angles of multiple rotations reaches more than 180°, but it is not necessary and reduces the detection efficiency.

[0074] Sixth embodiment

[0075] The imaging area of ​​the multilayer film optical element by the image acquisition device is smaller than the entire area of ​​the multilayer film optical element located at the hollow structure; in this case, the entire area needs to be divided into a plurality of target imaging areas.

[0076] There are multiple image acquisition devices, and the installation positions of the multiple image acquisition devices make their imaging areas of the multi-layer film optical element at least partially overlap;

[0077] The detection device further comprises a driving device, which is configured to drive the detection base to translate, or to synchronously drive the image acquisition device and its corresponding light source to translate;

[0078] for example Figure 1 The four image acquisition devices can only image half of the area divided into upper and lower parts of the overall area at a time. Therefore, the upper half of the target imaging area is imaged at four angles first, and then the detection base is translated or the image acquisition device and its corresponding light source are synchronously translated to image the lower half of the target imaging area at four angles.

[0079] Seventh embodiment

[0080] Different from the sixth embodiment, the installation orientations of the multiple image acquisition devices make them adjacent to the imaging areas of the multilayer film optical element, and correspondingly, the driving device is configured to synchronously drive the image acquisition devices and their corresponding light sources to rotate.

[0081] For example, there are four adjacent target imaging areas, such as Figure 1 As shown, the target imaging area A is correspondingly provided with a first image acquisition device 210 and a first light source 310, the target imaging area B is correspondingly provided with a second image acquisition device 220 and a second light source 320, the target imaging area C is correspondingly provided with a third image acquisition device 230 and a third light source 330, and the target imaging area D is correspondingly provided with a fourth image acquisition device 240 and a fourth light source 340.

[0082] Before being driven to rotate, the first image acquisition device 210 images the target imaging area A at a first angle, the second image acquisition device 220 images the target imaging area B at a first angle, the third image acquisition device 230 images the target imaging area C at a first angle, and the fourth image acquisition device 240 images the target imaging area D at a first angle;

[0083] Then, driven by the driving device, the first image acquisition device 210 images the target imaging area A at the second angle, the second image acquisition device 220 images the target imaging area B at the second angle, the third image acquisition device 230 images the target imaging area C at the second angle, and the fourth image acquisition device 240 images the target imaging area D at the second angle;

[0084] The execution is repeated to complete the process of four image acquisition devices capturing image information of four target imaging areas at multiple angles.

[0085] Eighth embodiment

[0086] Different from the sixth embodiment, the number of the image acquisition device is one, and the driving device is configured to drive the detection base to perform rotational and translational motions, or to synchronously drive the image acquisition device and its corresponding light source to perform rotational and translational motions.

[0087] Since there is only one image acquisition device, the detection base or the image acquisition device needs to perform both rotation and translation motion.

[0088] The idea of ​​the eighth embodiment is to use a single image acquisition device to sequentially and multi-angle image a plurality of target imaging areas divided on a large area. The driving device only needs to achieve this. As for the order of rotation and translation, and which one of the detection base or the image acquisition device performs the translation and which one performs the rotation, there is no need to limit it.

[0089] According to another aspect of the present invention, the present invention provides a method for detecting internal cracks in a multilayer film optical element, such as Figure 3 As shown, the detection method comprises the following steps:

[0090] Acquire a passband wavelength range of a multilayer film optical element to be detected, and select at least one light source within the passband wavelength range;

[0091] The multi-layer film optical element to be detected is suspended on a detection base with a hollow structure;

[0092] At least one image acquisition device is arranged on one side of the plane where the detection base is located, and at least one light source is arranged on the other side thereof, the image acquisition device corresponds to the light source one by one, and the area irradiated by the light source on the multilayer film optical element covers the imaging area of ​​the multilayer film optical element by the corresponding image acquisition device;

[0093] Lighting up the light source and triggering its corresponding image acquisition device to capture an image of a preset target imaging area; repeating this step at different imaging angles for the same target imaging area to obtain multiple images;

[0094] Identify whether all captured images have crack features. If not, determine that the multilayer film optical element does not have a crack defect in the target imaging area. Otherwise, determine that the multilayer film optical element has a crack defect in the target imaging area.

[0095] The detection method provided in this embodiment and the detection device provided in the above embodiment belong to the same inventive concept, and all the contents of the above detection device embodiment are incorporated into the present detection method embodiment by reference and will not be repeated here.

[0096] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0097] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A device for detecting internal cracks in a multilayer film optical element, characterized in that: It includes multiple image acquisition devices, multiple light sources and a detection base with a hollow structure, wherein the hollow structure of the detection base matches the multilayer film optical element to be detected, the wavelength of the light source is within the channel wavelength range of the multilayer film optical element; the multilayer film optical element is a planar structure; The image acquisition device corresponds to the light source one by one, and the corresponding image acquisition device and light source are respectively arranged on both sides of the plane where the detection base is located, the image acquisition device and the light source are not aligned, and the angle between the imaging optical axis of the image acquisition device and the optical axis of the light beam of the corresponding light source on the projection axis of the plane where the detection base is located is between 0° and 45°; The area where the light source irradiates the multilayer film optical element covers the imaging area of ​​the multilayer film optical element by the corresponding image acquisition device, and the image acquisition device is configured to be triggered to capture an image under the premise that the corresponding light source is lit; The image acquisition device is configured to meet the following conditions: the imaging area of ​​the multilayer film optical element by the image acquisition device is smaller than the entire area of ​​the multilayer film optical element located at the hollow structure, the installation orientations of the multiple image acquisition devices make their imaging areas of the multilayer film optical element at least partially overlap, and the portion of the multilayer film optical element located at the hollow structure is divided into multiple target imaging areas; The detection device also includes a driving device, which is configured to drive the detection base to rotate and / or translate within the plane where it is located, or to synchronously drive the image acquisition device and its corresponding light source to rotate and / or translate, each target imaging area is captured by multiple images by the multiple image acquisition devices, and the corresponding imaging angles of the multiple images captured of the same target imaging area are different.

2. The detection device according to claim 1, characterized in that: It also includes a processor, which is configured to identify whether there are crack features in all images captured of all areas on the multilayer film optical element. If not, the processor determines that the multilayer film optical element to be inspected does not have a crack defect; otherwise, it determines that the multilayer film optical element has a crack defect.

3. The detection device according to claim 1, characterized in that: The angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 10° and 80°; The angle between the optical axis of the light beam of each light source and the plane where the detection base is located is between 10° and 80°.

4. The detection device according to claim 3, characterized in that: There is a first angle between the imaging optical axis of the image acquisition device and the plane where the detection base is located, and there is a second angle between the light beam optical axis of the corresponding light source and the plane where the detection base is located, and the difference between the first angle and the second angle is between -30° and 30°.

5. The detection device according to claim 3, characterized in that: The angle between the imaging optical axis of each image acquisition device and the plane where the detection base is located is between 40° and 50°; The angle between the optical axis of the light beam of each light source and the plane where the detection base is located is between 40° and 50°.

6. The detection device according to claim 3, characterized in that: The imaging optical axis of the image acquisition device is coplanar with the optical axis of the light beam of the corresponding light source, and the plane where the detection base is located is located on the angular bisector plane between the imaging optical axis of the image acquisition device and the optical axis of the light beam of the corresponding light source.

7. The detection device according to any one of claims 1 to 6, characterized in that: There are multiple image acquisition devices, and the imaging area of ​​each image acquisition device for the multilayer film optical element covers the entire area of ​​the multilayer film optical element located at the hollow structure; The angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is greater than 0° and less than or equal to 60°.

8. The detection device according to claim 7, characterized in that: The included angle between the projection axes of the imaging optical axes of two adjacent image acquisition devices on the plane where the detection base is located is less than 55°; And / or, all the image acquisition devices are located on the same side of a virtual plane perpendicular to the detection base.

9. A method for detecting internal cracks of a multilayer film optical element based on the detection device according to any one of claims 1 to 8, characterized in that: include: Acquire a passband wavelength range of a multilayer film optical element to be detected, and select a plurality of light sources within the passband wavelength range; The multilayer film optical element is a planar structure; The multi-layer film optical element to be detected is suspended on a detection base with a hollow structure; A plurality of image acquisition devices are arranged on one side of the plane where the detection base is located, and the plurality of light sources are arranged on the other side thereof, the image acquisition devices correspond to the light sources one by one, the image acquisition devices are not aligned with the light sources, and the angle between the imaging optical axis of the image acquisition device and the light beam optical axis of the corresponding light source on the projection axis of the plane where the detection base is located is between 0° and 45°; the area where the light source irradiates the multilayer film optical element covers the imaging area of ​​the multilayer film optical element by the corresponding image acquisition device; Lighting up the light source and triggering its corresponding image acquisition device to capture an image of a preset target imaging area; Repeat this step at different imaging angles for the same target imaging area to obtain multiple images; Identify whether all captured images have crack features. If not, determine that the multilayer film optical element does not have a crack defect in the target imaging area. Otherwise, determine that the multilayer film optical element has a crack defect in the target imaging area.

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