CN110082360A - A kind of sequence optical element surface on-line detection device of defects and method based on array camera - Google Patents

Abstract

The invention provides an array camera-based on-line detection device and method for surface defects of sequential optical elements, including: an illumination system, an optical lens, a digital camera or an array camera, a two-dimensional motion device, and a digital image processor. The main innovation of the present invention is to use a two-dimensional motion device to drive the camera to translate in the horizontal and vertical directions to achieve the effect of an array camera, and the array camera detection system eliminates the need for focusing and imaging multiple optical elements at different object distances The cumbersome steps allow the imaging focal length of the imaging system to be flexibly changed by setting different reconstruction object distances. This method can be applied to the on-line detection of surface defects of optical components, and has great significance for improving the speed of simultaneous online detection of surface defects of multiple optical components.

Description

An array camera-based on-line detection device for surface defects of sequential optical elements and method

technical field

The invention belongs to the technical field of optical component defect detection, and specifically relates to an array camera-based online detection system and method for optical component surface defects, which can be applied to the online detection of optical component surface defects.

Background technique

When multiple optical components are in the working state of the optical system, due to environmental influences and other reasons, defects appear on the surface of the optical components. At this time, it is impossible to perform offline detection, but the impact of surface defects on the optical field cannot be ignored. The conventional on-line defect detection method based on the mechanical focusing method has other shortcomings such as long detection time and high requirements on the displacement accuracy of the platform. Since the defects on the surface of optical components will not only reduce the optical transmittance and generate stray light, but also seriously affect the beam quality. Under the action of the transmission light field in the optical system, the distribution of defects will continue to change until the system cannot be used normally. Monitoring is carried out at the initial stage of defect formation to facilitate timely repair and replacement. Therefore, the online detection of surface defects of optical components is of great importance to the continuous and healthy operation of the optical system.

Traditionally, there are two methods for detecting surface defects of optical components: off-line detection and on-line detection. Offline detection has high accuracy, but it takes a long time and the detection equipment is bulky. Using the optical component defect on-line detection device, the defect detection can be carried out when the optical component is fixed in the optical system, and the image of the damaged point can be statistically analyzed to obtain the defect distribution of the component. The optical component defect online detection device is actually a high-resolution zoom imaging system. The object distance of different optical components from the imaging system is different. By adjusting the focal length of the optical system, the magnification rate of surface defects of multiple optical components is kept constant. The zoom system generally moves the positions of multiple lens groups mechanically to achieve the change of the focal length, which can realize continuous zooming with high precision, but because the imaging system will generate a high-resolution image for each optical element, it will generate a huge amount of data. Subsequent image processing is relatively cumbersome. Moreover, the process of sequentially focusing multiple optical elements is time-consuming, making it difficult to realize real online detection. In some special optical systems, the detection time is strictly limited, and the online detection technology of multiple optical components defects based on mechanical focusing method has some shortcomings.

SUMMARY OF THE INVENTION

In view of the deficiencies of the traditional technology, the object of the present invention is to provide a device and method capable of on-line detection of surface defects of multiple optical elements, aiming at solving the problem of slow detection speed and low detection speed of existing online detection methods for multiple optical element defects. The process is complex and other problems, and the distribution of surface defects of optical components is intuitively displayed.

The technical scheme that the present invention will solve the problem that traditional technology exists adopts is:

On-line inspection device for surface defects of sequential optical elements based on array camera, including:

Illumination system, the illumination light source can be a laser or a bar-shaped or ring-shaped light-emitting diode light source, which is used to distinguish the imaging effect of the surface defect and non-defect area of the optical element;

The optical lens is used to collect the optical images of the detected optical elements under different object distances;

A digital video camera or array camera for converting images into corresponding digital image signals;

The two-dimensional motion device is used to drive the camera to realize X-Y two-axis translation to meet the positioning accuracy and range;

The digital image processor is used for storing the digital signal collected by the camera, digital refocusing calculation, image processing, judging whether the optical components are defective, and displaying the processing result of the digital image;

The array camera-based on-line detection device for surface defects of sequential optical elements uses a digital camera or an array camera to simultaneously collect images of surface defects of different optical elements within the depth of field, and then digitally refocuses the images to obtain images at different object distances. The surface defect distribution of multiple optical components.

The array camera-based on-line detection device for surface defects of sequential optical elements, wherein the detection light source illumination mainly includes the following three types: coaxial forward illumination; coaxial reverse illumination; edge light source illumination.

The array camera-based on-line detection device for surface defects of sequential optical elements, wherein a two-dimensional motion platform is used to drive the camera to realize X-Y two-axis translation, which can achieve the effect of an array camera;

An array camera-based online detection method for surface defects of sequential optical elements, comprising the following steps:

A. The detection task is determined, and the detection resolution index is determined accordingly. The lens and imaging system parameters are selected. The imaging system parameters include the pixel resolution and the number of pixels of the CCD sensor chip. Calculate the magnification according to the detection resolution to determine the focal length of the lens. Multiple optical components must be located within the depth of field of the imaging system, and the defect information on the surface of multiple optical components can be clearly imaged on the photosensitive surface of a single camera;

B. Carry out camera calibration, obtain the internal parameter matrix of the camera, change the baseline position size between the array cameras by moving the position of the camera through the displacement platform, and obtain the external parameters of the camera;

C. Cameras at different positions collect multiple images containing defect information of multiple optical components at the same time, and digitally refocus the images to obtain the surface defect distribution of multiple optical components. At this time, the surface defects of other optical components under the non-refocusing object distance Appears as out-of-focus aliased images in refocused images;

D. Filter and denoise the image after digital refocusing, obtain threshold binarization, extract the edge of the defect, and count the geometric information of the defect. The geometric information of the defect includes area, aspect ratio, perimeter and number, combined with the imaging system The magnification of the optical system obtains the distribution of defect information on the surface of multiple optical elements.

Compared with the prior art, the device and method for on-line detection of surface defects of sequential optical elements based on array cameras provided by the present invention have the following advantages: a single camera only produces one high-resolution image for multiple optical elements, and multiple optical elements based on array cameras The on-line detection technology of component surface defects has greatly improved the detection speed and the accuracy of detection results. Through digital refocusing to image the optical components within the depth of field, the surface defects of multiple optical components under different object distances can be visualized at the same time. It is shown that it is of great significance to the healthy operation of the auxiliary optical system.

Description of drawings

Figure 1 is a schematic diagram of the surface defect detection of optical components based on array cameras under the illumination of edge light sources;

Figure 2 is a schematic diagram of the surface defect detection of optical elements based on an array camera under coaxial forward illumination;

Fig. 3 is a schematic diagram of surface defect detection of optical elements based on an array camera under coaxial reverse illumination.

In the figure: 1 is a two-dimensional motion device, 2 is the first lighting source, 3 is the second lighting source, 4 is the third lighting source, 5 is the first optical element, 6 is the second optical element, 7 is the third optical Components, 8 is an image acquisition system, 9 is a digital image processor, 10 is a laser light source, 11 is a beam expander system, 12 is a plane mirror, 13 is a plane mirror, and 14 is an array image acquisition system.

Detailed ways

In order to make the technical solution of the present invention clearer, the present invention will be further described in conjunction with the drawings and specific embodiments.

Example 1

As shown in Figure 1, the present invention is an on-line detection device for surface defects of multiple optical elements based on an array camera, including: a two-dimensional motion device 1, a first lighting source 2, a second lighting source 3, and a third lighting source 4 , a first optical element 5, a second optical element 6, a third optical element 7, an image acquisition system 8 and a digital image processor 9; the image acquisition system 8 includes a CCD camera, a lens, and the like.

The illumination light source can be a laser or a bar-shaped or ring-shaped light-emitting diode light source. The selection of the light source mainly depends on the actual working conditions of the optical components in the optical system to determine different online detection methods.

After the detection resolution index is determined, select the pixel resolution and number of pixels of the CCD sensor chip of the lens and imaging system, and reasonably design the focal length of the lens, the size of the entrance pupil, and the size of the CCD pixel, so that multiple optical elements must be located Within the depth of field of the imaging system, the field of view is reasonable, and the defect information on the surface of multiple optical components can be clearly imaged on the photosensitive surface of a single camera. Combining with Figure 1, the surface defect detection method of optical components based on the array camera is as follows:

(1) First, the camera calibration step is performed to obtain the internal parameter matrix of the camera, and the external parameters of the camera are obtained by changing the baseline position and size of the array camera by moving the position of the image acquisition system 8 through the two-dimensional motion device 1 . Collect images of cameras at different positions to obtain multiple images containing defect information of multiple optical components at the same time;

(2) The image acquisition system 8 performs equidistant translation on the two-dimensional motion device 1, and obtains a series of projection images of the object plane on the image plane, which can realize sequential projection and imaging of scenes at different sampling points, thereby achieving the effect of an array camera, Save the cost of the camera and simplify the complexity of the acquisition system;

(3) After the array camera (or moving a camera position) collects the distribution of surface defects of the optical element within the depth of field, the different camera images are projected to the specified object distance for superimposition and averaging, which is equivalent to a virtual large The aperture lens reconstructs the surface defects of the optical element under the digital refocusing object distance. Due to the large aperture of the virtual lens, the imaging depth of field is very small. In addition to the clear imaging of the surface defects of the focused optical elements, the accumulated image plane of the defects of the optical elements at other object distances will be blurred;

(4) Perform image processing on the image after digital refocusing to extract clear defect information and accurate edge images, analyze and calculate the size of the defect to obtain the characteristics of the target image, and at this time, the surface defects of other optical components under the non-refocusing object distance Appears as out-of-focus aliased images in refocused images;

(5) Filter and denoise the refocused image, obtain threshold binarization, extract defect edges, and count geometric information of defects (area, aspect ratio, perimeter, number, etc.). Using the array camera-based online detection technology for surface defects of multiple optical components, it is possible to image the optical components within the depth of field within a short period of time, obtain defect distribution information on the surface of optical components, and better assist the operation of the optical system.

In summary, the present invention provides a plurality of optical element surface defect online detection devices and detection methods thereof, and the defect detection system mainly includes: a two-dimensional motion device 1, a first lighting source 2, a second lighting source 3, a third lighting A light source 4, a first optical element 5, a second optical element 6, a third optical element 7, an image acquisition system 8 and a digital image processor 9; the image acquisition system 8 includes a CCD camera, a lens and the like. First, the first lighting source 2, the second lighting source 3, and the third lighting source 4 illuminate the first optical element 5, the second optical element 6, and the third optical element 7 at the same time, and the existence of surface defects on the optical element will scatter the light. Scattered light is received by the lens and enters the image acquisition system 8 to convert it into a digital image signal, and the image is transmitted to the digital image processor 9 for storage in the form of a digital signal, and the digital refocusing algorithm and the method of extracting the surface defect information of the optical element from the refocused image The geometric features are calculated by the processor and finally displayed by the display module. The on-line detection technology of surface defects of multiple optical components based on the array camera greatly improves the detection speed, and visually displays the surface defects of multiple optical components.

Example 2

As shown in Figure 2, the online detection device for surface defects of multiple optical elements based on an array camera includes: a first optical element 5, a second optical element 6, and a third optical element 7; a digital image processor 9; a laser light source 10; A beam expander system 11; a plane mirror 12; a plane mirror 13; an array image acquisition system 14, the array image acquisition system 14 includes multiple lenses and a CCD camera.

Example 3

As shown in FIG. 3 , the online detection device for surface defects of multiple optical elements based on an array camera includes: a first optical element 5, a second optical element 6, and a third optical element 7; a digital image processor 9; a laser light source 10; A beam expander system 11; a plane mirror 12; an array image acquisition system 14, the array image acquisition system 14 includes multiple lenses and a CCD camera.

Comparing Figure 2 and Figure 3, the main difference of the surface defect detection method for optical elements based on array cameras lies in the illumination mode of the light source and the placement position of the array cameras. The actual working conditions may be different, and the detection methods shown in Figure 2 and Figure 3 can be selected.

In addition, referring to Figure 1, Figure 2, and Figure 3, there are mainly three detection lighting methods: Figure 1 uses edge light source lighting; Figure 2 uses coaxial forward lighting; Figure 3 uses coaxial reverse Illumination: The purpose of using the light source is to increase the difference between the imaging effect of the defect and the non-defect. Fig. 1, Fig. 2, and Fig. 3 are schematic diagrams of detection methods in three ways of illuminating surface defects of the optical element in different working states of the optical element in the optical system.

It should be noted that the application of the present invention is not limited to the above-mentioned examples, but only specific implementation modes of the present invention, which can be improved and transformed according to the description of the present invention, and should all belong to the protection scope of the claims of the present invention.

Claims (4)

1. a kind of sequence optical element surface on-line detection device of defects based on array camera, it is characterised in that: include: illumination System, optical lens, a digital camera or array camera, Two-dimensional motion device and Digital Image Processor；Wherein:

The lighting system, lighting source can be laser or bar shaped, ring-shaped light emitting diode light source, for distinguishing light Learn the imaging effect of element surface defect and non-defective region；

The optical lens, for acquiring the optical imagery of the detected optical element under different object distances；

The digital camera or array camera, for converting the image into corresponding data image signal；

The Two-dimensional motion device meets positioning accuracy and range for driving camera to realize the translation of two axis of X-Y；

The Digital Image Processor for being stored to the collected digital signal of camera, digital refocusing operation, is schemed As processing, judges whether optical element is defective, show the processing result of digital picture；

One digital camera or array camera collect the surface defect image of different optical elements within field depth simultaneously After, by carrying out multiple optical element surface defect distribution feelings under the available different object distances of digital refocusing to image Condition.

2. the sequence optical element surface on-line detection device of defects according to claim 1 based on array camera, special Sign is: array camera can be multiple cameras and integrate, and Two-dimensional motion device can also be used, camera is driven to realize that two axis of X-Y is flat It moves, to achieve the effect that array camera.

3. the sequence optical element surface on-line detection device of defects according to claim 1 based on array camera, special Sign is: the selection mode of light source depends primarily on practical working situation of the optical element in optical system to determine difference On-line checking mode, detection lighting method mainly has following three kinds: coaxial orthodromic illumination；Coaxial antidromic illumination；Edge light Illumination.

4. a kind of sequence optical element surface defect online detection method based on array camera, using described in claim 1 Sequence optical element surface on-line detection device of defects based on array camera, it is characterised in that: the following steps are included:

A, Detection task determines, detection resolution index determines therewith, selects camera lens and imaging system parameters, imaging system parameters Pixel resolution and pixel number including CCD sensing chip；Magnifying power, which is calculated, according to detection resolution determines lens focus, it is more A optical element all must be positioned in the field depth of imaging system, and the defect information of multiple optical element surfaces can be clear The photosurface in single camera be imaged；

B, camera calibration is carried out, the Intrinsic Matrix of camera is obtained, passes through the position change array phase of the mobile camera of displacement platform Baseline position size between machine obtains the outer parameter of camera；

C, camera collects several while including the image of multiple optical element defect informations at different location, counts to image Word refocusing obtains multiple optical element surface defect distributions, at this time other optical element surface defects under non-reunion focus-object distance The aliased image for showing as defocus in refocusing image；

D, denoising is filtered to the image after digital refocusing, obtains threshold binarization, edge extracting, statistical shortcomings it is several What information, area, length-width ratio, perimeter and number including defect obtain optical system in conjunction with the enlargement ratio of imaging system In multiple optical element surfaces defect information distribution.