Brian L. Justus

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We report lasing characteristics of 40-60-microm-diameter Rhodamine 590/water solution droplets pumped by a 20-nsec-duration Q-switched laser. The Rhodamine/water solution provides a useful model system for studying the properties of oscillators based on whispering-gallery-wave spherical cavities. The low threshold for lasing, 10(4) W/cm(2) for 10(-4) M(More)
Gated detection of the output of a fiber-optic-coupled radiation dosimeter effectively eliminated the direct contribution of Cerenkov radiation to the signal. The radiation source was an external beam radiotherapy machine that provided pulses of 6-MeV x rays. Gated detection was used to discriminate the signal collected during the radiation pulses,(More)
An optical fibre point dosemeter based on the gated detection of the luminescence from a Cu(1+)-doped fused quartz detector effectively eliminated errors due to Cerenkov radiation and native fibre fluorescence. The gated optical fibre dosemeter overcomes serious problems faced by scintillation and optically stimulated luminescence approaches to optical(More)
Fiber-optic-coupled radioluminescent (FOC) dosimeters are members of a new family of dosimeters that are finding increased clinical applications. This study provides the first characterization of a Cu doped quartz FOC dosimeter at diagnostic energies, specifically across the range of x-ray energies and intensities used in mammographies. We characterize the(More)
A novel approach for the fabrication of high-quality preforms for use in the fabrication of photonic crystal fibers is described. The preforms are fabricated in a multistep process that involves stacking a bundle with rods and (or) tubes of two dissimilar glasses, fusing the bundle, and then etching the fused bundle in acid to remove one of the two glasses.(More)
We describe an optically transparent, laser heated, thermoluminescent glass dosimeter that is used for fiber-optic-coupled remote radiation monitoring. The glass consists of ZnS nanocrystallites embedded in a Vycor glass host, doped with Cu and Nd ions. An 807 nm, 1 W GaAlAs laser is used to rapidly heat microscopic regions, surrounding the Nd ions, in the(More)
BACKGROUND This study is about the measurement of radiation dose contribution to the coronary arteries during intravascular brachytherapy with beta and gamma emitters utilizing in vivo optical fiber dosimeters. METHODS AND MATERIALS Domestic pigs were used. With each measurement, catheters were introduced into two different coronary arteries, including(More)
Operation of an f/5 thermal-defocusing/scattering optical limiter is described. Thermal-defocusing limiting of 6-ns-duration, 532-nm laser pulses occurs by use of the broadband-absorbing dye Nigrosin dissolved in carbon disulfide. Additional limiting due to thermally induced scattering occurs at high incident fluences (above a threshold fluence) when either(More)