A Thermal Residual Stress Repair Method for Fused Silica Laser Damage

Abstract

The invention provides a method for repairing laser damage of fused quartz without thermal residual stress. According to the method, rectangular laser pulses with high-peak power are acquired by intercepting peak segments of pulses output from a laser device; the rectangular laser pulses with high-peak power are focused, and single laser pulses with super-high-peak power density are acquired; the single laser pulses are used for peeling a material at a single point of a damaged part on a fused quartz substrate through transient gasification; the interval of the single laser pulses is controlled, so that the substrate is cooled sufficiently; gasification peeling is performed repeatedly through the single laser pulses until the material at the whole damaged part is removed. With the adoption of the method, high-temperature structural relaxation of the fused quartz substrate is effectively controlled, the damage of the fused quartz is repaired without thermal residual stress, the anti-damage capacity of damage points of a fused quartz optical element is improved, surface damage and development of surface damage of the fused quartz optical element are inhibited, the service life of the fused quartz optical element is prolonged, and the method has the advantages of short repair time, simple and efficient process, good process stability, high controllability and high repeatability.

Description

technical field [0001] The invention belongs to the technical field of optical materials and optical elements, and in particular relates to a heat-free residual stress repair method for fused silica laser damage. Background technique [0002] Due to its excellent chemical stability and good optical properties, fused silica materials are widely used in the preparation of optical components such as lenses, gratings, windows and shielding sheets in large-scale high-power laser systems. However, under the action of high-flux ultraviolet laser, the surface of fused silica optical components is prone to damage, and the damage size will expand rapidly with the increase of laser shots, seriously affecting the stability and service life of optical components. At present, the laser-induced damage on the surface of optical components is still the bottleneck that limits the throughput of high-power laser devices. Suppressing the surface damage and its growth of optical components to ens...

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Problems solved by technology

In 2012, Li Xibin and others adopted CO 2 The combination of laser and galvanometer system has achieved the repair of large damage points with a size of 500 microns, with a repair success rate of 80%, but there is serious residual stress after repair (Li Xibin et al. Strong Laser and Ion Beam, 24, 1757-1760 ( 2012))

In 2010, Liu Hongjie and others pointed out that CO 2 Laser thermal stress affects the damage threshold of fused silica, and thermal stress can exacerbate laser-induced damage growth, and it is considered that the currently used CO 2 The method of laser repairing defects cannot be applied to the processing of large aperture optical components (Liu Hongjie et al. Acta Physica Sinica, 59(2), 1308-1313(2010))

In order to avoid the generation of heat-induced stress when repairing the damage, in 2013, Fang Zhou et al. used femtosecond laser to repair the damaged point of fused silica. Femtosecond laser technology is an effective athermal processing technology, because the femtosecond pulse interacts with the material for a very short time. , the crystal lattice is hardly heated, which avoids the generation of thermal stress, but the femtosecond laser action is a very violent process, resulting in the formation of microcracks and easy laser damage materials in hard and brittle fused silica. It is found that hydrogen is needed after femtosecond laser treatment Subsequent processing such as hydrofluoric acid solution etching (Fang Zhou et al. Chinese patent, application publication number CN103232167A; Fang Zhou et al. China Laser, 40, 0403001 (2013)), femtosecond lasers have inherent defects in processing hard and brittle fused silica materials , it is difficult to apply engineering

[0004] Therefore, the existing fused silica damage repair methods do not yet have the ability to repair damage concisely and efficiently, and there is an urgent need for a heat-free residual stress repair method for fused silica laser damage

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