JPS5950937B

PURPOSE:To display reflecting waves from a sample clearly whithout being affected by multiple reflection waves in a focusing lens by setting the disposition of the ultrasonic focusing lens and the sample under predetermined conditions. CONSTITUTION:Signals from a high-frequency oscillator 1 are supplied to a transducer 3 through a coupler 2 and converted into ultrasonic waves. The ultrasonic waves are radiated to an ultrasonic focusing lens 4 and projected and focussed on a holding plate 5 through a sound field medium 6 such as water, etc. from a radiating surface 4a of the lens 4. The reflecting waves from the sample 7 advance backwardly in projection course and supplied to an indicator 10 through the coupler 2. A scanning device 8 moves the holding plate 5 in the directions (x), (y). A radius (r) of the radiating surface 4a, an apex 4b of the surface 4a, distanced between the apex 4b and the surface of the sample 7, distance l between the apex 4b and the input and outout surface of the lens 4 are set under predetermined conditions. Thus, a reflection wave C from the sample can be displayed between multiple reflection waves b1-b4 in the lens.