| First-Order Model of Thermal Lensing in a Virtual Eye |
Mar-2009 |
12 pages |
| Authors:
Clark; Robert J Thomas; Rebecca L Vincelette; Ashley J Welch; Benjamin A Rockwell; Clifton D III; TEXAS UNIV AT SAN ANTONIO
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 | An ABCD beam-propagation method was used to build a first-order mathematical model of a thermal lens effect from a near-infrared laser beam in water and ocular media. The model was found to fit experimental z-x scan data best when the thermo-optic coefficient dn/dT of liquid water at 292 K was -4.46x10(-5) K(-1). The physiological parameters of the human eye were simulated in a simple eye model using this fitted dn/dT ... |
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| Eliciting Action Potentials from Epidermal Stimulation of Skin Receptors Using Ultrashort Laser Pulses |
Feb-2009 |
16 pages |
| Authors:
Robert J Thomas; Douglas N Goddard; Michelle Imholte; Nicole Jindra; AIR FORCE RESEARCH LAB BROOKS CITY-BASE TX HUMAN PERFORMANCE WING (711TH)
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| Measurements of laser stimulated action potentials in the sciatic nerve of leopard frogs (Rana pipiens) were made using two ultrashort pulsed infrared lasers. The dorsal sides of the frog's hind limbs were exposed to 1540 nm and 1064 nm wavelengths at three separate spot sizes: 2 mm, 3 mm, and 4 mm. Energy density thresholds were determined for eliciting an action potential at each experimental condition. Results from these exposures ... |
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| Trends in Retinal Damage Thresholds from 100-Millisecond Near-Infrared Laser Radiation Exposures: A Study at 1,110, 1,130, 1,150, and 1,319 nm |
Jan 2009 |
10 pages |
| Authors:
Rebecca L Vincelette; Benjamin A Rockwell; Jeff W Oliver; Semih S Kumru; Robert J Thomas; Kurt J Schuster; Gary D Noojin; Aurora D Shingledecker; Dave J Stolarski; Ashley J Welch; AIR FORCE RESEARCH LAB BROOKS AFB TX HUMAN EFFECTIVENESS DIR/BIODYNAMICS AND PROTECTION DIV
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| Retinal damage thresholds from 100-millisecond exposures to laser radiation for wavelengths between 1,100 and 1,350nm have never previously been established. We sought to determine the retinal damage threshold for 100- millisecond exposures of near-infrared (NIR) laser radiation wavelengths at 1,110, 1,130, 1,150, and 1,319 nm. These data were then used to create trends for retinal damage thresholds over the 1,100?1,350nm NIR region based upon linear absorption of laser radiation in ... |
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| Epidermal Laser Stimulation of Action Potentials in the Frog Sciatic Nerve |
Oct-2008 |
16 pages |
| Authors:
Nichole M Jindra; Robert J Thomas; Douglas N Goddard; Michelle L Imholte; AIR FORCE RESEARCH LAB BROOKS AFB TX HUMAN EFFECTIVENESS DIR/DIRECTED ENERGY BIOEFFECTS DIV
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| Measurements of laser stimulated action potentials in the sciatic nerve of leopard frogs (Rana pipiens) were made using two infrared lasers. The dorsal sides of the frog's hind limbs were exposed to short-pulsed 1540 nm and 1064 nm wavelengths at three separate spot sizes: 2 mm, 3 mm, and 4 mm. Energy density thresholds were determined for eliciting an action potential at each experimental condition. Results from these exposures showed ... |
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| Thermal Lensing in Ocular Media Exposed to Continuous Wave Near-Infrared Radiation: the 1150-1350-nm Region |
Oct-2008 |
11 pages |
| Authors:
Robert J Thomas; Rebecca L Vincelette; Ashley J Welch; Benjamin A Rockwell; David J Lund; TEXAS UNIV AT AUSTIN DEPT OF BIOMEDICAL ENGINEERING
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| Abstract. Ocular damage threshold data remain sparse in the continuous wave CW, near-infrared NIR radiation region save for the 1300-nm area that has been investigated in the past several decades. The 1300-nm ocular damage data have yielded unusual characteristics where CW retinal damage was observed in rabbit models, but never in nonhuman primate models. This paper reviews the existing 1300-nm ocular damage threshold data in terms of the fundamental criteria ... |
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| An in vitro Corneal Model with a Laser Damage Threshold at 2 Micrometers That is Similar to That in the Rabbit |
Nov-2007 |
13 pages |
| Authors:
Robert J Thomas; Michael S Foltz; Michael L Denton; Kurt J Schuster; Larry E Estlack; NORTHROP GRUMMAN SAN ANTONIO TX
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| Corneal organotypic cultures were generated as per existing methods, which included growth on polycarbonate inserts and air-lifting for one week. The corneal simulant cultures were exposed, with real-time IR imaging, to the 2-micron wavelength output of a thulium fiber laser with 4 mm beam diameter for 0.25 seconds in a thermally controlled environment and then assayed for damage. The in vitro threshold (ED50 value of 12.5 W/sq cm) and peak ... |
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| Role of Superoxide Dismutase in the Photochemical Response of Cultured RPE Cells to Laser Exposure at 413 nm |
Nov-2007 |
9 pages |
| Authors:
Robert J Thomas; Michael S Foltz; Michael L Denton; Kurt J Schuster; Larry E Estlack; NORTHROP GRUMMAN SAN ANTONIO TX WARFIGHTER CONCEPTS AND APPLICATIONS DEPT
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| Thresholds for photochemical damage were performed in RPE cell lines (artificially pigmented) taken from either human (hTERT-RPE1), wild type (wt) mouse, or transgenic mice deficient (+/-) in either superoxide dismutase 1 (SOD1) or SOD2. The four cell lines were characterized by immunohistochemical and immunoblot analyses to determine relative abundance of the SOD proteins. There was no difference in sensitivity between the human, murine wt and murine SOD1-deficient cells, whereas there ... |
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