Laser Beam Divergence and Far Field Measurements.

摘要

Accurate determination of beam divergence and far field intensity distribution require careful determination that the far field is being examined. Although the far field exists at a sufficiently large distance from the laser,it is easier to perform measurements in the focal plane of a lens which is equivalent to an infinite distance. The beam divergence is specified as that angle which contains a certain percentage of the total power in the far field. Since this is a plane angle,confusion arises between the intensity distribution (w/sq. cm) and the power distribution (watts). Several methods are available for determining the divergence from the far field pattern. These methods are experimentally verified with a He-Ne laser. Construction of a unique portable two lens far field camera is discussed. (Author)