Optically excited atomic frequency standard

摘要

An optically-excited atomic frequency standard that subjects alkali metal atoms ( 111 ) to circularly-polarized optical radiation. The atomic frequency standard is improved by the use of a circular polarizer ( 202 ) to control the intensity of the circularly-polarized optical radiation. The circular polarizer includes a linear polarizer ( 203 ) and a quarter-wave retarder ( 205 ), with the light to be circularly polarized passing first through the linear polarizer ( 203 ) and then through the quarter-wave retarder ( 205 ). In the atomic frequency standard, the optical radiation ( 105 ) to which the circular polarizer ( 202 ) is applied is itself linearly polarized, and the intensity of the circularly polarized light produced by the circular polarizer ( 202 ) is controlled by rotating ( 303 ) the circular polarizer. The degree of rotation determines how much of the linearly-polarized optical radiation passes through the linear polarizer, and thus how much circularly-polarized light is produced.