ABSTRACT
Accurate measurements even of picosecond laser pulse lengths can be measured by a picosecond camera. This operates on the principle of "two photon fluorescence". The pulse length can be calculated from the photograph. The laser has made it possible to obtain accurate figures for the speed of light. In 1970, a group from the Massachusetts Institute of Technology made the high frequency measurement with lasers. The laser itself, especially the helium neon laser, is used frequently in the physics laboratory and in industry as a standard for accurate measurement. It can be used in the machine tool industry. The total energy is usually expressed in joules and the spot size is usually expressed in square centimeters. When applications are described, the type of laser and the technique of transmission should also include the output figures and the technique of measuring the output. Laser surveying and contouring have been mentioned before. Oceanography offers another field for accurate laser measurement and techniques.
