| 摘要 |
PURPOSE:To hold intensity of an outputted laser beam at a constant always by a method wherein a current is fed back to a coil of control system as to equalize a photoelectric voltage with the reference voltage and to regulate DC magnetic field generated by a magnetic field generating circuit. CONSTITUTION:DC magnetic field is generated in a gas laser tube LT by the magnetic field generating circuit MF, and a laser beam projected from the laser tube LT is introduced to a beam divider BS passing through a deflecting plate P. The laser beam is outputted and a part thereof is applied to a photo detector PM, and the difference between the laser beam and the reference voltage V0 is amplified by a differential amplifier A, and is amplified through a power amplifier PA. As a result, when the photoelectric voltage is smaller than the reference voltage V0, accordingly when intensity of laser output is smaller than the set point, a current in the coil C is increased by the control system to increase intensity of applying magnetic field. In opposition, when the photoelectric voltage is larger than the reference voltage V0, the current in the coil C is reduced to reduce intensity of applying magnetic field. Accordingly intensity of the outputted laser can be held at a constant. |
