energy per unit surface, it is based on the power or energy that can pass through a fully open pupil (0.39 cm2) for visible and near-infrared wavelengths. This is relevant for laser beams that have a cross-section smaller than 0.39 cm2. The IEC-60825-1 and ANSI Z136.1 standards include methods of calculating MPEs. Regulations In various jurisdictions, standards bodies, legislation, and government regulations define classes of laser according to the risks associated with them, and define required safety measures for people who may be exposed to those lasers. In the European Community (EC), eye protection requirements are specified in European standard EN 207. In addition to EN 207, European standard EN 208 specifies requirements for goggles for use during beam alignment. These transmit a portion of the laser light, permitting the operator to see where the beam is, and do not provide complete protection against a direct laser beam hit. Finally, European standard EN 60825 specifies optical densities in extreme situations. In the US, guidance for the use of protective eyewear, and other elements of safe laser use, is given in the ANSI Z136 series of standards. These consensus standards are intended for laser users, and full copies can be purchased directly from ANSI or the official Secretariat to the Accredited Standards Committee (ASC) Z136 and Publisher of this series of ANSI standards, the Laser Institute of America. The standards are as follows: ANSI Z136.1 – Safe Use of Lasers As the parent document of the Z136 series of laser safety standards, the Z136.1 is the foundation of laser safety programs for industry, military, research and development (labs), and higher education (universities). ANSI Z136.2 – Safe Use of Optical Fiber Communication Systems Utilizing Laser Diode and LED Sources This standard provides guidance for the safe use, maintenance, service, and installation of optical communications systems utilizing laser diodes or light emitting diodes operating at wavelengths between 0.6 μm and 1 mm. Optical communication systems include end-to-end optical fiber based links, fixed terrestrial point-to-point free-space links, or a combination of both. ANSI Z136.3 – Safe Use of Lasers in Health Care Provides guidance for individuals who work with high power Class 3B and Class 4 lasers and laser systems in health care. ANSI Z136.4 – Recommended Practice for Laser Safety Measurements for Hazard Evaluation Provides guidance for measurement procedures necessary for the classification and evaluation of optical radiation hazards. ANSI Z136.5 – Safe