| 摘要 |
PURPOSE:To obtain a small-sized and inexpensive polarization plane controller by disposing 1st and 2nd polarizing means in place of a Faraday element as a polarization plane control element and disposing an electrooptic element and a polarized beam splitter behind said element. CONSTITUTION:Light from a light source 1 to be measured is bisected by a branching filter 21. One thereof enters an acoustooptic optical modulator 3 by which the light is shifted to enter the 1st polarizing means 23a. A voltage is impressed to the respective elements of the means 23a by which the polarization plane is rotated. This light is circularly polarized by the electrooptic element 24a and is linearly polarized by the element 24b. The light is then entered to the polarized beam splitter 26a to allow transmission of the P wave. This light is entered to an optical coupler 27. On the other hand, the incident light on a delay optical fiber 22 enters the 2nd polarizing means 23b. A voltage is impressed to the electrooptic elements 24c, 24d and the splitter 26b by which the light from the fiber is so controlled as to transmit the splitter 26b at a higher rate. The transmitted light enters the coupler 27. The light interferes with the previous P wave and is converted by a photoelectric converter element 28a to an electric signal which is sent to a measuring instrument.
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