| 摘要 |
An apparatus for controlling a light quantity comprises a light source for emitting light and an acousto optical modulating element, having a driving unit for giving a progressive wave to a medium, for generating 0th-order and higher-order diffracted beams of light by an acousto optical effect of the progressive wave. The apparatus also comprises a stop element which transmits, not the higher-order diffracted beams, but the 0th-order diffracted beam; and a drive controlling section for varying a quantity of light irradiating an object by regulating the progressive wave through the driving unit.
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