| 摘要 |
801,294. Ultrasonic inspection devices. SMYTH, C. N. March 2, 1956 [Dec. 2, 1954], No. 34917/54. Class 118 (2). [Also in Group XL (a)] An arrangement for producing visible images of sound vibrations comprises a sound-electron current piezo-electric transducer 1, a conducting layer 2 in contact therewith on one side, a photo-sensitive layer 3 in contact therewith on the other side and optical means for scanning the layer 3 in synchronism with the scanning of a picture reproducer which obtains the light modulation from output signals derived from the photo-sensitive . layer. As shown, the transducer in the form of a crystal plate 1 is sealed as a window at the end of a vacuum tube T to whose metal cover 2 is sealed an oil- or water-filled tank for producing ultrasonic images of the required sound vibrations. The photo-electric layer 3 is scanned by light SP from a cathode-ray tube C and the electrons thereby produced flow to an open-mesh grid collector 4 in dependence on the potential difference between layer 1 and collector 4 and on the piezo-electric voltage. The load on resistance 5 is thereby used to modulate the beam of a cathode-ray tube receiver to give an optical picture of the sound image. The photoemissive layer may be a mosaic to which the electron charge is restored by electron bombardment from a photo or thermionic cathode 6 which is rendered negative to the layer 3 during the scanning light spot flyback time. Alternatively the layer 3 may be photo-conductive covered by a semi-transparent conducting film. Specification 477,139 is referred to. |
