Study on the Absorption Characteristics and Laser Damage Properties of Fused Silica Optics under Flexible Polishing and Shallow DCE Process.

Wanli Zhang,Feng Shi,Ci Song,Ye Tian,Yongxiang Shen

doi:10.3390/mi12101226

Wanli Zhang, Feng Shi + Show 3 more

Open Access

https://doi.org/10.3390/mi12101226

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Journal: Micromachines	Publication Date: Oct 8, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: National University of Defense Technology

Abstract

The enhancement of laser damage resistance of fused silica optics was a hotspot in scientific research. At present, a variety of modern processes have been produced to improve the laser induced damage threshold (LIDT) of fused silica optics. They included pre-treatment processes represented by flexible computer controlled optical surfacing (CCOS), magnetorheological finishing (MRF), ion beam finishing (IBF), and post-treatment processes represented by dynamic chemical etching (DCE). These have achieved remarkable results. However, there are still some problems that need to be solved urgently, such as excessive material removal, surface accuracy fluctuation in the DCE process, and the pollution in MRF process, etc. In view of above problems, an MRF, CCOS, IBF and shallow DCE combined technique was used to process fused silica optics. The surface morphology could be greatly controlled and chemical etching depth was reduced, while the LIDT increased steadily. After processing by this combined technique, the LIDT increased to 12.1 J/cm2 and the laser damage resistance properties of fused silica were significantly enhanced. In general, the MRF, IBF, CCOS and shallow DCE combined technique brought much help to the enhancement of laser damage resistance of fused silica, and could be used as a process route in the manufacturing process of fused silica.

Highlights

As a material with excellent optical properties, fused silica was widely used in the manufacturing process of key optics in high-energy laser systems, such as National IgnitionFacility (NIF) in the United States, SG-III laser facility in China and Laser Megajoule system in France, etc. [1,2,3]
After the computer controlled optical surfacing (CCOS) process, the error amplitude significantly decreased and the power spectral density (PSD) curve remained unchanged after the shallow dynamic chemical etching (DCE) process
The shallow DCE process would not affect the amplitude of frequency errors

Summary

Introduction

As a material with excellent optical properties, fused silica was widely used in the manufacturing process of key optics in high-energy laser systems, such as National IgnitionFacility (NIF) in the United States, SG-III laser facility in China and Laser Megajoule system in France, etc. [1,2,3]. As a material with excellent optical properties, fused silica was widely used in the manufacturing process of key optics in high-energy laser systems, such as National Ignition. [1,2,3] For these laser systems, their service performance and life were limited by the quality and laser damage characteristics of fused silica optics. Pre-treatment processes including reactive ion etching (RIE) and post-treatment processes including dynamic chemical etching (DCE) had already been developed by scholars, which were applied to manufacture fused silica optics and achieved good results. Sun Laxi found that RIE technology could significantly improve the laser induced damage threshold (LIDT) of fused silica optics [4]. J. Bude found particle pollution on the surface limited the LIDT improvement of fused silica optics. Through the modern process technique, the LIDT of fused silica had been greatly improved

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