Stress induced birefringence of glass-to-metal bonded components

Samuel N. Hann, Nathan Macleod, Paulina O. Morawska, Adrian Dzipalski, Richard M. Carter, Ian Elder, Robert A. Lamb, Matthew Jan Daniel Esser, Duncan Paul Hand

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Abstract

We report on the stress induced birefringence of 10 mm BK7 cubes bonded to 15 mm x 15 mm x 5 mm aluminium coupons using ultrashort pulse laser welding, hydroxide catalysis bonding, and an optical adhesive using a standard approach used in industry. It was observed that ultrashort pulse laser welding results in a low level of stress induced birefringence within an 85% optical aperture of the 10 mm cube. These levels are suitable for use in photography and microscopy applications as defined by the relevant ISO standard for permissible stress induced birefringence limits in optics. Hydroxide catalysis bonding was shown to approach and possibly exceed this limit, however, it must be noted that the bonding area of the hydroxide catalysis samples greatly exceeds that of the welding and adhesive bonded samples by a factor of 20 and thus will likely experience grater mechanical stress from defects on the metal surface. The induced stress in the adhesively bonded samples was found to be well-confined, with the retardation falling below the maximum acceptable limits for microscopy type applications of 10 nm/cm retardation within 0.5 - 1 mm of the glass-metal interface for the majority of samples tested. The hydroxide catalysis and ultrashort pulse laser welded samples have a significant increase in retardation in the region directly above the bonded surface compared to the adhesively bonded samples. This retardation decays rapidly as a function of distance from the bonded interface. In the case of ultrashort pulse laser welded samples, optimisation of the welding parameters has been shown to control the level of retardation within the interface region, thus reducing the overall effect of the weld on the bulk optic.
Original languageEnglish
Title of host publicationEmerging Imaging and Sensing Technologies for Security and Defence V; and Advanced Manufacturing Technologies for Micro- and Nanosystems in Security and Defence III
PublisherSPIE
ISBN (Electronic)9781510638938
DOIs
Publication statusPublished - 20 Sep 2020
EventSPIE Security + Defence 2020 - Digital
Duration: 21 Sep 202025 Sep 2020
https://spie.org/conferences-and-exhibitions/security-and-defence

Publication series

NameProceedings of SPIE
Volume11540
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceSPIE Security + Defence 2020
Period21/09/2025/09/20
Internet address

Keywords

  • Birefringence
  • Circular polariscope
  • Laser materials processing
  • Lasers and laser optics
  • Optical design and fabrication
  • Polarisation
  • Stress induced birefringence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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