Radiometry and laser safety standards

The application of occupational limits (ELs) in the outdoor laser environment requires an understanding of the radiometric methods required to evaluate field exposures with respect to the ELs. The limiting aperture required to adequately specify the EL must always be kept in mind. Since all exposure limits are defined as a function of time, electro-optical detectors and instrumentation must have an adequate temporal response and have an absence of saturation effects. As a field-expedient method thermally sensitive paper can also be employed to estimate the output radiant exposure of pulsed lasers. For evaluating potential ocular hazards in the retinal hazard spectral region (400 to 1400 nm), one should employ a 7-mm aperture. For evaluating potential hazards to the skin and the cornea, a 1-mm limiting aperture is justified. Although the impact of the 1-mm limiting aperture is to reduce the limiting power which is considered safe—the accessible emission limit for Class 1 laser products, it nevertheless is justified for field exposure of the eye, as has been shown in recent experimental studies of corneal injury.