| 摘要 |
PURPOSE:To simplify the device constitution and reduce its cost, and prevent its malfunction by passing exciting laser beam through two optical paths which have a temperature difference, and detecting the direction and degree of deviation in phase matching state from the difference of a light mixed wave output. CONSTITUTION:The 1st constant temperature part 12 in a constant temperature oven 2 is set to higher temperature than the 2nd constant temperature part 13. The exciting laser beam from a laser beam source 1 is split to the 1st and the 2nd optical paths through the 2nd beam splitter 15 and a reflecting mirror 14 and guided to the 2nd and the 3rd photodetectors 20 and 22 through the 3rd and the 4th beam splitters 21 and 23. A dividing circuit 19 calculates the ratio of the output of the 2nd photodetector 22 to the output of the 2nd photodetector 20 and a differential amplifier 17 amplifies the difference between the output of a voltage generator 18 which generates a reference voltage and the output of the dividing circuit 19 and inputs the difference signal to a temperature control unit 16 as the error signal of the differential amplifier 17. The temperature control unit 16 controls the constant temperature part 13 in the constant temperature oven 2 to desired temperature on the basis of the error signal. |
