STP911: Laser Damage in Plastics at the Frank J. Seiler Research Laboratory (FJSRL)

    O'Connell, RM
    University of Missouri-Columbia, Columbia, MO

    Saito, TT
    University of Missouri-Columbia, Columbia, MO

    Deaton, TF
    University of Missouri-Columbia, Columbia, MO

    Siegenthaler, KE
    University of Missouri-Columbia, Columbia, MO

    McNally, JJ
    University of Missouri-Columbia, Columbia, MO

    Shaffer, AA
    University of Missouri-Columbia, Columbia, MO

    Pages: 11    Published: Jan 1985


    Abstract

    In order to study ways to improve the laser damage resistance of transparent polymers and thereby realize their advantages for high power laser system applications (e.g., they are lightweight, inexpensive, and castable), a laser damage program has been established at FJSRL. In this paper we describe the damage facility and present the results obtained during the initial year of the program.

    The heart of the damage facility is a 1.06-micron wavelength Q-switched Nd:YAG laser capable of providing 300 mJ, 8 nsec FWHM pulses at repetition rates up to 10 pps. For the results reported here, the beam was focused to a 46 micron 1/e2 spot diameter.

    Extensive single and multiple-shot bulk damage studies were made of several commercially available materials including polymethylmethacrylate (PMMA), three grades of polycarbonate (PC), and cellulose acetate butyrate (CAB). Measured single-shot damage thresholds were, respectively, 41 J/cm2, 15 J/cm2, and 15 J/cm2, which correlates with the relative “dirtiness” of the materials. Of the three materials, PMMA also had the greatest multiple-shot damage resistance. However, at fluence levels ≤ 0.1 times its single-shot threshold, CAB appears to be remarkably damage resistant.

    Preliminary measurements were also made on PMMA which was synthesized in-house from both unpurified and moderately purified monomers, both with and without unpurified plasticizers. The single-shot damage threshold of the material made from purified monomers (no plasticizer) was 1.6 times that of the material made from unpurified monomers. The multiple-shot behavior of the purified material as compared to that of the unpurified material was even more remarkable.

    Keywords:

    bulk laser damage, cellulose acetate butyrate, multiple-shot, single-shot, plastics, polycarbonate, polymethymethacrylate


    Paper ID: STP28957S

    Committee/Subcommittee: F01.11

    DOI: 10.1520/STP28957S


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