Optical density measurements of laser eye protection materials

Abstract

One of the primary safety concerns of laser users in the potential range of incurring laser induced eye damage. In this regard, various types of protective eyewear are available for use in shielding the user’s eyes from the harmful effects of intense laser radiation. Proper protective eyewear is chosen by selecting materials whose inherent transmission characteristics are appropriate for the expected laser operating conditions (e.g. wavelength, power level, etc). For convenience, the transmittance values of protective eyewear are typically expressed in terms of optical density (i.e. the logarithm to the base 20 of the reciprocal of the transmittance) for specific laser wavelengths. These optical density values are usually stamped or printed on the eyewear assemblies.An Ad-Hoc Committee on Laser Protection serving under the auspices of the Control Measures Subcommittee of the American National Standards (ANSI) identified the need to study several factors of laser protective devices. This group, comprised of representatives from several of the leading eyewear manufacturers along with a number of the ANSI Z136 control measures committee members, asked the optical Electronics Metrology Group of the National Institute of Standards and Technology (NIST), Boulder, CO to perform optical density measurements on selected protective eyewear samples as part of this study. Measurements were also to be performed by the Laser Electro-Optics Engineering Technology Department of the Cincinnati Technical College (CTC), Cincinnati, OH on the same materials.This paper describes the measurement methods and results of the optical density measurements performed by NIST and CTC on designated protective eyewear samples at several specific laser wavelengths. The measurement configurations and associated measurement error sources will also be reviewed.One of the primary safety concerns of laser users in the potential range of incurring laser induced eye damage. In this regard, various types of protective eyewear are available for use in shielding the user’s eyes from the harmful effects of intense laser radiation. Proper protective eyewear is chosen by selecting materials whose inherent transmission characteristics are appropriate for the expected laser operating conditions (e.g. wavelength, power level, etc). For convenience, the transmittance values of protective eyewear are typically expressed in terms of optical density (i.e. the logarithm to the base 20 of the reciprocal of the transmittance) for specific laser wavelengths. These optical density values are usually stamped or printed on the eyewear assemblies.An Ad-Hoc Committee on Laser Protection serving under the auspices of the Control Measures Subcommittee of the American National Standards (ANSI) identified the need to study several factors of laser protective devices. This group, comprised o...