An investigation of a solid-liquid phase-change-cooled mirror

• Published in: Journal of modern optics Vol. 52; no. 9; pp. 1319 - 1326
• Main Authors: Lu, Yuling, Cheng, Zuhai
• Format: Journal Article
• Language: English
• Published: London Taylor & Francis Group 15.06.2005; Taylor & Francis
• Subjects: Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lenses, prisms and mirrors; Optical elements, devices, and systems; Optics; Physics; Thermal strain; Cooling; Unstable resonator; Digital simulation; Laser-radiation heating; Theoretical study; Experimental study; Telescopic mechanism; Phase transitions; Optical resonators; Confocal resonator; Liquid solid transition; Metal mirror; Silicon; Optical elements; Copper; Mirrors; Helium-Neon lasers; Reflecting surface
• ISSN: 0950-0340; 1362-3044
• DOI: 10.1080/09500340512331337885

This article details a new design for a laser-reflecting mirror utilizing phase-change-cooling technology, which is innovative in using spiral cooling ducts filled with solid-liquid phase-change material to maintain a constant temperature inside the reflecting mirror in a positive-branch telescopic, virtually confocal unstable resonator. The structure no longer needs the 45° scraper plate that is always utilized in a positive-branch telescopic, virtually confocal unstable resonator for coupling the output and provides a high-quality coaxial laser output. The numerical calculation results show, that when phase-change cooling is utilized, the localized maximum temperature dropped from 44 to 33°C. Experiments show that the total surface deformation of a copper mirror dropped from 1.4 µm to 0.27 µm when using phase-change cooling, after continued laser exposure for 10 s and, under the same conditions, that of a silicon mirror dropped from 1.1 µm to 0.4 µm.