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    Non-Destructive Damage Studies of Ruby Laser Rods

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    We have developed a non-destructive test technique for the evaluation of ruby laser rods using Electron Spin Resonance (ESR). The rods are mounted in a specially designed holder external to the microwave spectrometer. The apparatus is designed so that localized regions of the rod of approximately 1 cm3 in volume are examined during each run. Merely by translating the rod through the holder a map of ESR spectra throughout the entire rod can be obtained. We have compared the ESR spectra of new Czochralski ruby obtained in this manner with that of severely damaged rubies obtained from the Air Force Weapons Laboratory. In addition, spectra obtained in the conventional manner (that is, sample mounted in a cavity) of small, high-quality ruby samples were compared to the data obtained using this new technique. Other than a reduction in sensitivity which occurs as a result of the absence of a resonant cavity, the spectra of high quality rubies using both techniques are almost indistinguishable. However, remarkable differences in the spectra of damaged and undamaged rods were observed in line broadening and in Une shape. The linewidths of undamaged SIQ ruby were found to be uniform throughout the volume of the rods. Variations of a factor of 5 in the width of the resonance were observed in the damaged rods. In some instances, the nature of the broadening strongly suggests the existence of microscopic crystallites with small misorientation of the respective c axes. Highly anomalous line shapes, in some cases multiply split, were observed in the damaged samples. The variation in the splitting in some cases was in good agreement with distortion in the fringe pattern observed in the rod through crossed polarizers. Evidence of local (within 1 cm3) damage has been found which was not observed in contiguous regions. However, similarities in the line shape over several cm3 have also been observed in some instances, suggesting the existence of long-range damage. The spectra observed in some regions of the damaged rod strongly indicate domain structure.


    lasers, ruby laser damage, non-destructive testing, damage, glass electron parametric resonance, optical properties, tests, evaluation

    Author Information:

    Chicklis, E.
    MITHRAS Division of Sanders Associates, Cambridge, Mass.

    Schwartz, J.
    MITHRAS Division of Sanders Associates, Cambridge, Mass.

    Pitha, Carl A.
    Air Force Cambridge Research Laboratories, Bedford, Mass.

    Committee/Subcommittee: F01.03

    DOI: 10.1520/STP48611S