| 摘要 |
PURPOSE:To reduce the size and cost of an acoustooptic element by setting up a light incident angle to the axis of crystal in a half of an acoustooptic medium to a large value to provide the medium with a filtering function and setting up a light incident angle to the axis of crystal in the residual half so as to provide the medium with a wide band deflecting characteristics. CONSTITUTION:When multicolor light to be vertical straight polarization is made incident, diffracting action is generated by an acoustooptic effect due to ultrasonic waves generated from the 1st transducer 12a. Since the incident angle to the axis of crystal is set up to a large value, its light diffracting condition is restricted, light selecting action is obtained as narrow band characteristics and monochromatic light can be selected from the incident polychromatic light. Since non-selected light 19 and filter light 18 are polarized light vertical to paper surface, the deflected state of incident light to a deflecting part of the latter half part is restricted only to a polarized state horizontal to the paper surface, so that these light beams 19, 18 are not deflected. Only filtered light 20 is made incident upon the latter half part and deflected by the diffracting action based upon acoustic waves generated from the 2nd transducer 12b. Thus, the acoustooptic element can be reduced at its size and cost.
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