The primary objective of this effort is to develop a low-cost, self-powered, and compact laser event recorder and warning sensor for the measurement of laser events. Previously we reported on the technology and design of the Laser Event Recorder. In this paper we describe results from a series of ground and airborne tests of the Laser Event Recorder.
Lasers for defense applications continue to grow in power and fill in new portions of the spectrum, expanding the laser eye safety hazard, particularly to aircrew and aviation safety. The Laser Event Recorder Program within Naval Air Systems Command (NAVAIR) seeks to develop a low cost, self-contained laser sensor able to detect, warn and record laser exposures that hazard aircrew vision. The spectral and temporal range of hazardous lasers (400 to 1600 nm and pulsed to continuous) has presented a challenge in the past. However, diffractive optics and imaging technologies have enabled a solution to this growing threat. This paper will describe the technical requirements for the Laser Event Recorder, which are based on ANSI Z136.1 laser safety standards and common to its use on any platform. To support medical and operational laser eye protection, the LER extracts and records laser wavelength, radiant exposure, exposure duration, pulse structure, latitude, longitude, altitude and time of laser exposure. Specific performance and design issues of the LER prototype will be presented in a companion paper. In this paper, fundamental challenges to the requirements encountered during the first two years of research, development and successful outdoor testing will be reviewed. These include discrimination against all outdoor light levels and the impact of atmospheric beam propagation on accuracy of the radiant exposure determination. Required accuracy and response time of the determination of whether a laser exposure exceeds the maximum permissible exposure (MPE) will be described. Ongoing efforts to coordinate laser exposure reporting and medical management will also be discussed.
Laser eye protection (fixed wavelength) can be grouped into three broad categories: adsorptive (dyes, phosphate glass), interference (dielectric, holographic and rugate), or hybrid (i.e., absorptive and interference, interference and interference, etc.). The approaches differ markedly in design complexity, cost, and their impact on visual performance. The challenge is to achieve a balance between complexity and cost while minimizing the impact on visual performance. The data to be discussed are resolution thresholds set by five observers with a corrected or uncorrected acuity of 20/20. The observer modulates the spatial frequency of a sinusoidal grating while grating contrast is fixed at 5, 10, 20, 40 and 80%. The first study quantifies visual performance from low photopic (10 ftL) down through low scotopic light levels (5E-5 ftL). The data show a sharp drop in acuity as ambient light level drops from 1 to .001 ftL (roughly equivalent to a quarter moon). The second study measures visual acuity over the same range of light levels while the observer wears: (1) multi line absorptive laser eye protection, (2) hybrid laser eye protection, and (3) neutral density equivalents. The results demonstrate that once the data is normalized for spectral compatibility and scotopic transmittance there are no significant differences between the filters. A third study assesses the loss in visual performance as scotopic transmittance is reduced from 40 to 30 to 20%. The implications for filter requirements and design will be discussed.
Conference Committee Involvement (1)
Laser and Noncoherent Light Ocular Effects: Epidemiology, Prevention, and Treatment III
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.