This document provides information on the physical aspects of electromagnetic radiation in the optical spectrum, within the wavelength range of 100 mm - l mm. Optical radiation includes ultraviolet radiation (UVR) from approximately 100 nm to 400 mm, light (visible radiation) from approximately 400 nm to 760 on, and infrared radiation from approximately 760 mm to 1 mm. Each of these spectral regions can be arbitrarily divided into subregions. Lasers are capable of producing optical radiation in all three major divisions of the optical spectrum. A brief survey of lasers and other man-made sources of optical radiation is presented. It is known that optical radiation interacts with biological systems and a summary of knowledge on biological effects and health aspects has been included in this document. It is hoped that this criteria document may provide useful information for the development, at a national level, of protection measures against non-ionizing radiation.