System for testing damage threshold of optical element surface and test method

Abstract

The invention discloses a system for testing damage threshold of optical element surface and a test method thereof and relates to the field of optical detection. The system of the invention comprises a laser, a liquid crystal light valve, a beam splitter, a first lens, a test sample, an absorption trap, a direct-vision CCD, a reflector, a bulk absorption meter, a second lens and a monitoring CCD which are successively arranged according to a light path. According to the damage threshold test method, a mapping relation between the liquid crystal light valve and near-field facula is established to obtain transfer function; coordinate of a damage spot in the facula is introduced into the transfer function to determine occlusion region of the liquid crystal light valve; and local flux is calculated after the occlusion region covers the damage spot. According to the invention, calculation accuracy of damage threshold is raised.

Description

technical field [0001] The invention belongs to the field of optical detection, and in particular relates to an optical component surface damage threshold testing system and a testing method thereof. Background technique [0002] At present, the laser damage threshold detection of optical components is mainly to test the irreversible damage to the surface of optical components caused by surface defects of optical components under strong laser irradiation. Surface defects of optical components mainly refer to structural defects and defects introduced by grinding and other processing processes. Residual impurity elements will cause damage to the surface of optical components when irradiated with laser light. The damage threshold detection is mainly to detect the damage threshold caused by defects. [0003] However, the existing damage threshold testing methods usually calculate the average flux in the laser spot as the damage threshold. Due to the difference in the distributio...

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Problems solved by technology

However, this test method still cannot accurately describe the damage threshold of defects, and the shortcomings are mainly manifested in:

[0005] 1. The size of the initial damage point on the surface of the component is usually 10 μm to 50 μm, and the area of ​​the test spot is usually on the order of millimeters, which is much larger than the area of ​​the damage point. The calculation of the average flux of the entire spot causes a decrease in accuracy

[0006] 2. The laser spot used in the damage threshold test is usually a Gaussian spot and a flat-top spot. The intensity distribution of the Gaussian spot is strong in the middle and weak on both sides, while the intensity distribution of the flat-top spot is uneven. The average flux and peak flux of the two kinds of spots There is a large difference in the amount, resulting in inaccurate test results

[0007] 3. The direct cause of the surface damage of optical components is that the local flux around the defect exceeds the damage threshold of the defect. Under laser irradiation, the defect is damaged to form a damage point, while other areas of the laser spot do not cause damage, and the entire spot is calculated. The light intensity reduces the correlation with damage

[0008] 4. The damage threshold of different types of defects is not the same. The existing damage testing technology cannot avoid the damage of low-threshold defects in high-flux laser irradiation. The damage threshold of the test shows that the damage threshold of the defect is not higher than the test laser flux

There is a certain deviation between the test result and the real damage threshold of the defect, which makes the test result inaccurate

[0009] Therefore, the existing damage threshold detection system and test method are difficult to guarantee the accuracy and accuracy of the damage threshold test of optical components, and it is urgent to invent a more accurate test method and test system to characterize the damage of optical components and accurately reflect the damage of optical components. The laser flux suffered when it occurs, improves the accuracy of the damage threshold test, and realizes the accurate test of the damage threshold of the local area of ​​​​the surface defect of the optical component. The results are of great significance for evaluating the quality of the optical component

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