| 摘要 |
PURPOSE:To easily adjust the focus position with a high precision by adjusting temperatures of a semiconductor laser and a collimator lens on a basis of the temperature control signal from a temperature control circuit. CONSTITUTION:When temperatures of a semiconductor laser 10 and a collimator lens 18 are changed, mutual positional relations between the laser 10 and the lens 18 and the refractive index of the lens 18 are changed to move the focus position of a laser beam 16 forward or backward. Consequently, temperatures of the laser 10 and the lens 18 are properly changed by a temperature adjusting device 40 and the focus position is moved forward or backward in accordance with this change to easily adjust the focus position with a high precision without moving the lens, a mirror, etc.
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