ode of operation used by most laser transceivers draws a major concern of the laser ocular hazard introduced to the human eye. This is because the tissues of the human eye are very susceptible to damage that is dependent on wavelength, power, and pulse duration. More specifically, specific tissues in the eye interact strongly with different portions of the optical spectrum. The cornea and lens are transparent to the visible wave- lengths and near-infrared exposure as they are intended to focus visible light onto the retina. However, mid-infrared (1,400 nm to 3 um) to far- infrared (3 um to 1 mm) exposure to the cornea and lens can cause pho- tokeratitus and cataracts. Due to the potential danger of a transceiver laser to the human eye, it is critical to enforce stringent laser safety stan- dards established earlier to all optical transceiver products distributed worldwide. One of the widely adopted laser safety standards comes from the International Electrotechnical Commission (IEC). The IEC 60825-1 Safety of Laser Products Part 1-Equipment Classification, Requirements, and User Guide is an internationally recognized technical standard for users and manufacturers of laser products. This standard applies to the laser safety classification system that is mandatory on all wireless optical laser transceivers. Table 9-17 shows the classification system of the IEC 60825-1, as applied to the example of a doubled CW Nd:YAG laser. Table 9-1 Class Description Classification System of the Lasers that are safe under reasonably foreseeable conditions. 0.39 uW IEC 60825-1 Visible lasers (400-700 nm) where aversion response such as the blink reflex affords eye protection. Lasers that are safe for viewing with the unaided eye. Direct viewing of the beam with aids (such as binoculars) may be hazardous. Lasers that are hazardous when the beam is viewed directly. 500 mW Lasers capable of producing hazardous diffuse reflections >500 mW and that may pose skin and fire hazards. Chapter 9 A safe operation of the laser transceiver requi