| 摘要 |
PURPOSE:To suppress a deviation in wavelength with temperature and to reduce errors in speed measurement by controlling a semiconductor laser to constant temperature. CONSTITUTION:A heat-sensitive element 12 detects the temperature of the semiconductor laser 2 and inputs it to an error amplifier 13. The amplifier 13 compares it with reference temperature T0 and the power amplification of the difference signal is performed to drive an electrothermal converter 15. The converter 15 is composed of a Peltier element; and one side of the element is joined with the laser 2 and heat is radiated from the other. When the temperature of the laser 2 is higher than a reference temperature T0, a positive current flows to the converter 15 to cool the laser, but when the temperature is lower, on the other hand, a negative current flows to heat the laser 2, which is controlled to the constant temperature T0 at all times. Thus, speed measurement errors due to a wavelength deviation are reduced.
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