CN106841236B - Transmission optical element defect testing device and method - Google Patents

Abstract

In order to solve the disadvantages of traditional testing methods that are time-consuming and labor-intensive, and the measurement of defects inside optical components is limited, the present invention provides a testing device and method for testing defects in transmission optical components, wherein the device includes a laser, a collimator, a fixed Focus lens, CCD, moving mechanism and acquisition control computer; The collimating lens is arranged on the output optical path of the laser; The fixed focus lens and CCD are rigidly connected to form an imaging system, and the monitoring surface of the imaging system is photosensitive through the fixed focus lens and CCD The planes are in a conjugate relationship; the imaging system is fixed on the moving mechanism; the moving mechanism is connected with the acquisition control computer.

Description

Defect testing device and method for transmission optical element

technical field

The invention belongs to the field of optics, and relates to a method and a device for testing defects of optical components, in particular to a method and a device for testing the surface, sub-surface and internal defects of a transmissive large-diameter flat plate and wedge in a laser light path.

Background technique

The Shenguang III host device uses a large number of flat and wedge optical components. The flat and wedge defects will cause damage to the components at a lower flux. Laser-induced damage will accelerate the damage of the components, and at the same time cause the beam of the device to The deterioration of the quality will affect the output energy and focusing characteristics of the device, generate thermal images in the subsequent optical path, cause new damage, and reduce the energy of shooting, which is extremely harmful. Therefore, the control of defects in the flat plate and wedge in the device is very important.

Traditional testing methods:

Method 1, visual method, with the help of a low-magnification magnifying glass to observe the surface, sub-surface and internal defects of the plate and wedge. When this method is used to test large-caliber components, long-term observation of the human eye is likely to cause visual fatigue, and the measurement confidence Low, this method is time-consuming and labor-intensive, and the efficiency is low.

Method 2, micro-imaging method, using a mobile scanning mechanism to carry large-diameter optical components, using LED lighting, using dark-field imaging, and testing the defects of optical components by a CCD microscopic system. This method is affected by the field of view and working distance of the microscopic system. Due to the limitation of optical components, it can only test the defects on the surface or sub-surface of optical components, and the measurement of defects inside the optical components is limited. At the same time, the microscope system is used, the field of view is small, and the scanning method takes a long time to measure.

Contents of the invention

In order to solve the shortcomings of traditional testing methods that are time-consuming and labor-intensive, and the measurement of internal defects of optical components is limited, the present invention proposes a method and device for testing defects of transmission optical components, which can test the surface and interior of large-diameter transmission optical components Rapid detection of defects.

Technical solution of the present invention is as follows:

The test device for flaws in transmission optical components is special in that it includes a laser, a collimating mirror, a fixed-focus lens, a CCD, a moving mechanism, and an acquisition control computer; the collimating mirror is set on the output optical path of the laser; the The fixed-focus lens and CCD are rigidly connected to form an imaging system, and the monitoring surface of the imaging system forms a conjugate relationship with the CCD photosensitive surface through the fixed-focus lens; the imaging system is fixed on a moving mechanism; the moving mechanism is connected with an acquisition control computer.

In order to improve detection efficiency and realize automatic testing, the above test device also includes a stage and a scanning mechanism; the stage is used to place and fix the optical element to be tested; the scanning mechanism is used to move the stage and the An optical element; the scanning mechanism is connected with the acquisition control computer.

The method for using the above-mentioned testing device to detect defects in transmission optical elements is special in that it includes the following steps:

1) Turn on the laser 1 and inject the laser into the collimating mirror for collimation;

2) Make the collimated laser beam irradiate a certain area to be tested of the optical element under test;

3) Observe the image of the imaging system, if there is a diffraction pattern, it indicates that there is a defect in the currently irradiated area of the optical element under test, and proceed to step 4);

4) Adjust the position of the moving mechanism along the axial direction so that the diffraction ring changes from large to small until the diffraction ring disappears. At this time, the monitoring surface of the imaging system coincides with the defect position of the optical element under test;

5) Move the optical component under test so that the laser beam passes through the next test area of the aperture of the optical component under test, and use the same method as steps 3) to 4) to test this area;

6) Repeat step 3) to step 5), until the test of all areas of the entire optical element is completed;

7) Splicing the position data of defects in all test areas to obtain the spatial defect information of the entire optical element.

In the above step 5), the optical element to be tested is placed on the stage, and the scanning mechanism is used to move the stage and the optical element to be tested as a whole.

The advantages of the present invention are:

1. The present invention combines a laser, a collimating mirror, a stage, a scanning mechanism, a fixed-focus lens, a CCD, a moving mechanism and an acquisition control computer, utilizes the diffraction characteristics of the laser and the conjugate imaging relationship of the object image, and realizes large-scale The defect detection of aperture optical components can detect the surface, sub-surface and internal defect information of the entire optical component, and the measurement of defects inside the optical component is not limited, and the detection efficiency is high. , even if the scale is on the submicron scale, it can produce clear diffraction fringes, so the system has high measurement accuracy.

2. The invention has a high degree of automation and is suitable for non-destructive non-contact precision measurement of optical element defects.

Description of drawings

Fig. 1 is a mechanism schematic diagram of the present invention;

In the figure, 1-laser, 2-collimating mirror, 3-stage, 4-scanning mechanism, 5-fixed focus lens, 6-CCD, 7-moving mechanism, 8-acquisition control computer, 9-optics to be tested element.

Detailed ways

The test device for defects in transmission optical elements provided by the present invention includes a laser 1, a collimating mirror 2, a stage 3, a scanning mechanism 4, a fixed-focus lens 5, a CCD 6, a moving mechanism 7 and an acquisition control computer 8.

The collimating mirror 2 is arranged on the output optical path of the laser 1, and collimates the output laser light of the laser to output a parallel beam.

The stage 3 is used to place the optical element to be tested, and ensure that the optical element to be tested is located on the output optical path of the collimating mirror 2, so that the parallel light beam passes through a certain test area of the optical element to be tested.

The scanning mechanism 4 is installed at the lower end of the stage 3, and is used for moving the stage 3 and the optical element to be tested placed on the stage 3 as a whole, so that the laser beam passes through the next test area of the optical element to be tested.

The fixed-focus lens 5 and the CCD 6 are rigidly connected to form an imaging system. Whole imaging system is fixed on the moving mechanism 7, and the monitoring surface of imaging system becomes conjugate relationship by fixed-focus lens 5 and CCD 6 photosensitive surfaces. The imaging system is used to test whether there are defects in the current test area of the optical component to be tested.

The scanning mechanism 4, the imaging system and the moving mechanism 7 are all connected to the acquisition control computer 8;

Acquisition control computer 8 has three functions:

1. Control the moving steps of the scanning mechanism and the moving mechanism;

2. Data collection: including the position information of the monitoring surface of the imaging system and the irradiated area information of the optical element under test;

3. Data processing: splicing the position of each area where the optical element under test has defects, and obtaining the spatial defect information of the entire optical element.

Based on the above test device, the present invention also provides a method for testing defects in transmission optical elements, comprising the following steps:

1) Turn on the laser 1, inject the laser into the collimating mirror 2, collimate it into a parallel beam, fix the optical element under test on the stage 3, and make the parallel beam irradiate a certain area of the optical element under test; The straight parallel light enters the imaging system composed of fixed-focus lens 5 and CCD 6 after being transmitted by the optical element under test.

2) If a diffraction pattern appears on the imaging system, it indicates that there is a defect in the irradiated area of the optical element under test, and proceed to step 3).

3) Adjust the position of the moving mechanism 7 along the axial direction (parallel to the axial direction of the collimating mirror). When the diffraction pattern on the imaging system gradually becomes smaller, it indicates that the monitoring surface of the imaging system is gradually approaching the defect position of the optical element under test; Continue to adjust the position of the moving mechanism 7. When the diffraction ring disappears, the principle of image transfer is satisfied, which means that the monitoring surface of the imaging system coincides with the defect position of the optical element under test at this time.

4) Move the stage 3 and the optical element under test as a whole, so that the laser beam passes through the next test area of the aperture of the optical element under test, and use the same method as steps 2) to 3) to test this area.

5) Repeat step 2) to step 4) until the test of the entire optical element is completed.

6) Splicing the defect position data of all test areas to obtain the spatial defect information of the entire optical element.

The specific splicing method in step 6) here is a common technical means for data processing by those skilled in the art, and the present invention will not repeat them here.

Claims (2)

1. A method of detecting a transmission optical element defect, comprising:

the adopted testing device for the defects of the transmission optical element comprises a laser, a collimating mirror, a fixed-focus lens, a CCD (charge coupled device), a moving mechanism and an acquisition control computer; the collimating lens is arranged on an output light path of the laser; the fixed-focus lens and the CCD are rigidly connected to form an imaging system, and a monitoring surface of the imaging system is in conjugate relation with a CCD photosurface through the fixed-focus lens; the imaging system is fixed on the moving mechanism; the moving mechanism is connected with an acquisition control computer;

the method comprises the following steps:

1) Starting a laser, and injecting laser into a collimating mirror for collimation;

2) Irradiating a certain to-be-tested area of the tested optical element by the collimated laser beam;

3) Observing an image of the imaging system, if a diffraction pattern appears, indicating that a defect exists in the currently irradiated area of the optical element to be detected, and entering the step 4);

4) Adjusting the position of the moving mechanism along the axial direction to make the diffraction ring gradually smaller until the diffraction ring disappears, wherein the monitoring surface of the imaging system is superposed with the defect position of the measured optical element;

5) Moving the optical element to be tested, enabling the laser beam to pass through the next test area of the caliber of the optical element to be tested, and testing the area by adopting the same method of the steps 3) -4);

6) Repeating the steps 3) to 5) until the test of all the areas of the whole optical element is finished;

7) And splicing the position data with the defects in all the test areas to obtain the spatial defect information of the whole optical element.

2. A method of detecting transmission optical element defects according to claim 1, characterized in that: the method comprises the following steps: and 5) placing the optical element to be measured on the objective table, and integrally moving the objective table and the optical element to be measured by adopting a scanning mechanism.

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