A method for detecting subsurface defects of optical glass

Abstract

The invention relates to a method for detecting subsurface defects of optical glass. The steps include: preparing glass samples with subsurface defects by using asphalt or polyurethane polishing; reasonably determining sample sampling points to comprehensively evaluate the subsurface defects of the samples; making removal areas according to the sampling points It is a regular-shaped removal function, which is convolved with the dwell time to obtain a number of regular-shaped sampling areas; use the above-mentioned removal function and ion beam processing to uniformly remove the sampling area at different depths; use the surface topography observation equipment to observe the sampling area, Obtain the subsurface defect morphology of optical glass. The invention adopts ion beam processing to remove the hydrolyzed layer on the surface of different sampling points in the full field of view of the optical glass, and uses surface microscopic topography detection equipment to observe it; the invention has the characteristics of simple principle, accurate and intuitive measurement results, and avoids the use of Hydrofluoric acid is a safe and effective method for measuring subsurface defects.

Description

technical field [0001] The invention relates to the field of optical processing and detection, in particular to a method for detecting subsurface defects of optical glass. Background technique [0002] The photolithography machine used in the manufacture of large-scale integrated circuits can expose and produce tens of nanometer feature size patterns to meet the needs of smaller and smaller chip sizes and higher integration. As the most important part of the lithography machine, the projection lithography objective lens is currently the most complicated optical system, and its manufacturing process puts forward extremely high requirements on optical design, processing, inspection and assembly. For optical processing, there will still be subsurface defects in optical glass after polishing. The existence of these defects, especially microcracks, will enhance the local field under high-energy laser irradiation, reducing the ability of optical materials to resist laser damage, ...

AI Technical Summary

Problems solved by technology

Since silicon dioxide only reacts with hydrofluoric acid, hydrofluoric acid can only be used as the acid for corrosion. Hydrofluoric acid itself is very corrosive, and the reaction between the two produces silicon fluoride gas, which is a colorless and poisonous gas, so hydrogen Protection is more important during the use of hydrofluoric acid and corrosion; magnetorheological processing is a non-destructive processing method, but it, like other processing methods using polishing fluid, will produce a hydrolyzed layer on the surface of optical glass, although it is thinner than the general hydrolyzed layer, It is also not possible to directly observe subsurface defect conditions

refer to figure 2 , in the past optical glass sub-surface defect detection technology, (a) and (b) are the confocal microscopy method and the total internal reflection microscopy method in the non-destructive testing methods, which have the disadvantages of expensive equipment and unintuitive and reliable results; (c) and (d) are glued polishing hydrofluoric acid corrosion method and magnetorheological method, which have problems such as poor safety and unintuitive results

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