ULTRASONIC MICROSCOPE.

摘要

An ultrasonic beam converged through an acoustic lens (3) is emitted on a sample, and it is reflected onto a transducer (2) and converted into an electric signal. The electric signal is partly picked up by a gate (8), and the signal is input to an attenuator (9) which determines any input/output ratio. The strength of the signal from the attenuator is compared with a treshold by a comparator (11), and the gain of the attenuator is adjusted depending upon the result of comparison so that the input/output ratio of the attenuator will assume a desired value. The focal point of the acoustic lens is calculated by a computer (14) based on a characteristic curve of attenuator gain corresponding to the travel of the acoustic lens toward the sample from a position sufficiently away from the focal point, and a drive signal that corresponds to the calculated result is output to a Z-drive control unit (16). As a result, the distance between the acoustic lens and the sample is adjusted fo focus the lens.