Repair of a mirror coating on a large optic for high laser damage applications using ion milling and over-coating methods

Journal Article · Fri Jul 08 00:00:00 EDT 2016 · Optical Engineering

DOI:https://doi.org/10.1117/1.OE.56.1.011002· OSTI ID:1356302

Field, Ella S. ^[1]; Bellum, John C. ^[1]; Kletecka, Damon E. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Here, when an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched. Repairs were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO₂ and SiO₂ layers for high reflection at 1054 nm at 45 deg incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm². The repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 to 61.0 J/cm².

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1356302
• Alternate ID(s): OSTI ID: 1502886; OSTI ID: 1315584
• Report Number(s): SAND--2016-5219J; 653055
• Journal Information: Optical Engineering, Journal Name: Optical Engineering Journal Issue: 1 Vol. 56; ISSN 0091-3286
• Publisher: SPIE
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
HfO2
SiO2
ion etching
ion milling
laser damage
optical coatings