PURPOSE: To enhance isolation and facilitate assembling and adjusting work and control by disposing two Faraday rotors between two doubly refracting plates, and disposing a polarizer between the Faraday rotors.
CONSTITUTION: A ray (a) of light emitted from a semiconductor laser beam source enters a first doubly refracting plate 29 and is separated into normal and abnormal rays of light having planes of vibration perpendicular to each other. The normal ray of light incident on a first Faraday rotor 31 has its plane of polarization rotated clockwise by 45 degrees and the abnormal ray of light has its plane of polarization rotated counterclockwise by 45 degrees so that the planes of polarization of the two rays of light coincide with each other. Because a polarizer 33 is so disposed that the direction in which polarized light is transmitted through it coincides with the planes of polarization of the two rays of light, the two rays of light are transmitted through the polarizer 33 and the plane of polarization of the normal ray of light incident on a second Faraday rotor 32 is rotated clockwise by 45 degrees to form an abnormal ray of light, and the plane of polarization of the abnormal ray of light is rotated counterclockwise by 45 degrees to form a normal ray of light, and the normal and abnormal rays of light are coupled together by a doubly refracting plate 30. Reflected light (b) incident from the reverse direction is separated into two rays of light, which are blocked by the polarizer 33.
TAKANO TOSHIHIKO
TAKEDA NORIO
ARII KOZO
