| 摘要 |
PURPOSE:To improve the performance of the information reader by laser light by automatically adjusting a light quantity adjusting filter by a feedback means so that the quantity of laser light irradiating on an information recording part is a specific quantity. CONSTITUTION:If the quantity of the laser light irradiating on the information recording part decreases below the specific quantity owing to a decrease in the output of laser light emitted by a laser light generator 1, a light quantity detection sensor 5a detects a decrease in the quantity of the other laser light branched by a half-mirror 3 in proportion to the decrease. The transmissivity of the light quantity adjusting filter 2 to the laser light is increased automati cally according to the detection signal so that the quantity of the laser light irradiating on the information recording part reaches the specific quantity. Consequently, even if the quantity of the laser light emitted by the laser light generator 1 decreases for various reasons, the quantity of the laser light irradiat ing on the information recording part reaches the specific quantity to prevent the performance from degrading. |
