Laser scanning type microscope equipped with aotf

PROBLEM TO BE SOLVED: To guarantee the stability of laser performance to necessary ultraviolet-ray wavelength and a visible spectrum range by providing a temperature sensor at the periphery of an acoustooptical temperatures sensor(AOTF) or nearby it or while the temperature sensor is coupled with the AOTF. SOLUTION: Temperature detectors which detect ambient temperatures of respective AOTFs are fitted directly to the AOTFs and the temperatures are transmitted to a central control unit 34 which has an arithmetic function. The arithmetic function adjusts and optimizes the AOTF-to-frequency relation of temperature dependency in a frequency range by a previously stored correction curve and a driving circuit. Namely, a frequency shift caused by variation in temperature is compensated by increasing or decreasing the frequency. This compensation can be performed on the basis of the intensity value of a laser beam picked off by a diode 19. Namely, an AOTF driver controls the frequency by varying the frequency up to the highest frequency according to the intensity signal picked off by the diode 19.