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Proceedings Paper

Human performance decrements associated with the bandwidth of laser protective eyewear concepts
Author(s): Jerome W. Molchany; David J. Lund
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Paper Abstract

Protecting the eye from coherent light sources is of critical concern to both military and civilian laser users. Laser protective eyewear degrades visual performance. Common and emerging applications use lasers emitting at numerous wavelengths or single lasers emitting at multiple wavelengths. Protection against multiple wavelengths increases the difficulty in selecting or building protective eyewear and concomitantly usually increases the performance penalty. Pursuit tracking performance decrements were measured as a function of bandwidth and peak wavelength transmission for 12 bandpass filters. Eight volunteers tracked a target subtending 34 milliradians (mrad) at a constant velocity of 5 mrad/sec for 15 sec. The target traversed an arc located 5 m from the tracker. Each volunteer received two training days and two test days. Twelve bandpass filters, with bandwidths of 10, 25, 40, and 70 nm, and peak wavelengths of 450, 550, and 650 nm were randomly inserted into the optics of the tracker. No volunteer received all 4 bandwidths of one peak wavelength on either test day, thereby reducing any adaptational effect. Luminance was equated across filters using Neutral Density (ND) filters. An ND filter of equal Optical Density served as the control. The total luminance at the eye was 0.8 cd/m2. Trials were collected at a rate of 4 per filter. The 10 nm blue filter elicited the poorest performance, followed by the 25, 40, and 70 nm blue filters. The red filters enhanced performance across all but the narrowest bandwidth. It can be assumed that the blue end of the visible spectrum with it's `forward of the retina' focusing properties and the low number of blue photoreceptors are responsible for the large decrements. Current philosophy in laser eye protection is to allow as much of the blue end of the spectrum through a filter to preserve scotopic transmission. The shortwave transmission may inadvertently increase error rates for visual tasks.

Paper Details

Date Published: 1 April 1996
PDF: 10 pages
Proc. SPIE 2674, Laser-Inflicted Eye Injuries: Epidemiology, Prevention, and Treatment, (1 April 1996); doi: 10.1117/12.237510
Show Author Affiliations
Jerome W. Molchany, Walter Reed Army Institute of Research (United States)
David J. Lund, Walter Reed Army Institute of Research (United States)

Published in SPIE Proceedings Vol. 2674:
Laser-Inflicted Eye Injuries: Epidemiology, Prevention, and Treatment
Bruce E. Stuck; Michael Belkin M.D., Editor(s)

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