Thermal and optical performance characteristics of a spatial light modulator with high average power picosecond laser exposure applied to materials processing applications

Guangyu Zhu, David Whitehead, Walter Perrie, Olivier Allegre, Vojtech Volle, Qianliang Li, Yue Tang, Karl Dawson, Jin Yang, Stuart Edwardson, Lin Li, Geoff Dearden

    Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

    Abstract

    A spatial light modulator (SLM) addressed with Computer Generated Holograms (CGH’s) can create structured light fields when an incident laser beam is diffracted by a phase CGH. The power handling limitations of SLMs based on a liquid crystal layer have always been of some concern. Now, with careful engineering of chip thermal management, we present the detailed optical phase and temperature response of a liquid cooled SLM exposed to picosecond laser average powers up to 220W at 1064nm – new knowledge critical for determining device performance at high laser powers. SLM chip temperature rose linearly with incident laser exposure, increasing by only 5°C at 220W incident power, measured with a thermal imaging camera. Thermal response time with continuous exposure was 1-2 seconds. The optical phase response with incident power approaches 2π radians with average powers up to 130W while above this power, liquid crystal thickness variations limit phase response to just over π radians. These remarkable performance characteristics show that liquid crystal based SLM technology is highly robust when efficiently cooled. High speed, multi-beam plasmonic surface micro-structuring at a coverage rate of 8cm2s-1 is achieved on polished metal surfaces at 25W exposure, while diffractive multi-beam surface ablation on stainless steel at an ablation rate of ∼4mm3min-1 is demonstrated with average power 100W. Continuous exposure for many hours exceeding 100W laser power did not result in any detectable drop in diffraction efficiency hence no permanent changes in SLM phase response characteristics have been observed This research work will help to accelerate the use of liquid crystal SLMs for both scientific and ultra-high throughput laser-materials micro-structuring applications.
    Original languageEnglish
    Title of host publicationProcedia CIRP
    PublisherElsevier BV
    Pages594-597
    Number of pages4
    Volume74
    DOIs
    Publication statusPublished - 2018

    Publication series

    NameProcedia CIRP
    PublisherElsevier BV
    ISSN (Print)2212-8271

    Keywords

    • Active cooling
    • High average power picosecond laser
    • High power laser micro-machining
    • Spatial light modulator

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