| 摘要 |
PURPOSE:To prevent destruction due to the contact between an acoustic lens and a sample, to perform quick, high-speed focus adjustment, and to obtain an image with constant contrast, by automating the focus adjustment. CONSTITUTION:A piezoelectric transducer 3 projects an ultrasonic wave upon a sample 8, a gate circuit 23 is opened, and a counter 25 starts counting clock pulses from an oscillator 24. The detection signal for a reflected wave from the sample 8 is converted into a pulse, which closes the gate circuit 23 to stop the counting of the counter 25. An arithmetic control circuit 13 fetches the count value to find the distance between the acoustic lens 4 and the sample 8, and also fetches set focal length to find the extent the direction of a shift from the focus position. On the basis of the shift, a driving device 12 detects the Z-axial position of the acoustic lens 4 and simultaneously the lens is moved in the opposite direction to the shift through a Z-axis position controller 15 and driving device 12, thus completing the focus adjustment. |
