Automatic evaluation system for bulk defects in optics. (February 2021)

• Record Type: Journal Article
• Authors: Wang, Shiling; Sun, Huanyu; Liu, Ang; Zhang, Jianpu; Cheng, Xinglei; Huang, Jin; Wang, Fengrui; Liu, Dong; Liu, Chong
• Is Part Of: Optics and lasers in engineering. Volume 137(2021)
• Publication Date: 2021-02
• Subjects: Bulk defects -- Dark field scattering imaging -- Three dimensional reconstruction -- Optics; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2020.106380
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: A special mechanical structure of the displacement platform is designed for four beams of light to intersect at the detection location in optics. The problem of defocusing caused by the refractive index of samples is solved by moving a focus compensation motion unit in real time. Three-dimensional information of the bulk defects of the fused silica samples was quantitatively obtained with the proposed reconstruction algorithm. Abstract: In the high frequency laser system, the internal defects of optics will affect their damage threshold and downstream modulation, and even lead to subsequent surface damage. In order to efficiently and reliably evaluate the internal defects in optics, an automatic evaluation method of scattering defects in optics is proposed, and the corresponding three-dimensional (3D) precision measurement system is established. The detection principle, image acquisition, image processing and bulk defects (BDs) information extraction methods of the system are studied. Based on a 3D dark-field microscopic imaging (DFMI) technology, samples are scanned with multi-dimensional motion devices. Meanwhile, the scattered beam from the BD was collected by a detector, and finally combined with the digital image processing technology, the acquired images are processed in real time. Through real-time focusing and improved 3D reconstruction algorithm, the images with full aperture BD features are obtained, and the position and size information of defects are extracted. The system has detected the BD inside the fused silica samples. The results show that our system can distinguish the 612.7 lp/mm. Furthermore, the 3D distributions of the BD were also reconstructed.