Laser safety for electro-optical imaging systems: exposure limits and hazard distances

Abstract

Laser safety with regard to the human eye is a well-known topic. Everybody working with laser sources has to follow the long-established occupational safety rules to prevent people from eye damage by accidental irradiation. These rules comprise, for example, the use of laser safety eyewear and the calculation of the maximum permissible exposure (MPE) and its corresponding hazard distance, the nominal ocular hazard distance. At exposure levels below the MPE, glare effects may occur if the laser wavelengths are in the visible spectral range. The physical effects of laser dazzling on the human eye are described by a quite new concept, which defines the maximum dazzle exposure (MDE) and the corresponding nominal ocular dazzle distance (NODD). Triggered by the MDE/NODD concept, we investigated whether similar laser safety calculations could be performed for electro-optical imaging systems. In this publication, we will review our approach for laser safety calculations for such systems. We have succeeded in finding closed-form equations, allowing calculations of exposure limits to prevent electro-optical imaging systems from damage and/or dazzle. Furthermore, we found some interesting effects related to the corresponding hazard distances, which are also discussed.