Patent GB-1421575-A (GB)
Title: Methods and apparatuses for ultrasonic examination
IPC: G01N29/26
Filed: 1973-03-08
Abstract: 1421575 Ultrasonic inspection AKADEMIET FOR DE TEKNISKE VIDENSKABER SVEJSECENTRALEN 8 March 1973 [28 Aug 1972] 11327/73 Heading H4D A method of and apparatus for inspecting inhomogeneities in bodies having plane or slightly curved surfaces in which an ultrasonic probe transmits pulses obliquely into a test body in a predetermined direction and an indicating device produces point markings on a plane record surface, wherein the markings are effected along an axis of indication which in relation to the record surface follows the direction of the pulses projected on the body surface, a reference point on the axis of indication follows the movement of the probe over the body surface and each marking is effected at a distance from the reference point proportional to the pulse echo travel time. Probe 4 emits pulses of ultrasound along a direction 5 at a fixed angle 6 to the body surface 3. A planar record medium 9 has markers 7 which lie along a line 11 coincident with the pulse direction. Echo pulses are relayed to conventional receiving apparatus and the marker energized at the appropriate range. Thus as the probe 4 is moved over the surface 3, a composite picture 10 of the inhomogeneity 2 is built up. Several embodiments are described divided into two types (1) with the recording surface fixed over the surface of the test body and (2) remote recording surfaces. In the first type, e.g. Fig. 2, the probe 4 carries a rigid arm 15 which has markers 7 along its length. These may be spark gap generators (Fig. 3, not shown) or lightemitting diodes (Fig. 4, not shown) which mark an appropriately sensitive record medium 9 in response to echo signals derived from ultrasonic receiver 14. The light-emitting diodes may be used in conjunction with a camera. In a modification, (Fig. 5, not shown), the upper surface of the arm 15 has light-emitting diodes which give a visual representation to the operator of pulse echoes. In a further embodiment (Fig. 6, not shown) the marking signals are derived from the receiver CRT via optical fibres which are mounted such that their one ends lie along the CRT trace and their other ends lie along the arm 15. In the Figs. 7-9 (not shown) embodiments a single marker is used which is continuously moved along the arm and is responsive to echoes from the appropriate range to mark the record 9. The marker is moved along a rod (Fig. 8, not shown) or is fixed to an endless belt (Fig. 9, not shown). In the Fig. 10 arrangement, the marker takes the form of a helical strip 38 on a roller 37 which rotates about an axis parallel to the indication axis 11. As the roller rotates, the point of contact 40 with the record sheet is scanned along the indication axis 11. In those embodiments using remote indication, the probe position is resolved electrically or mechanically (Figs. 12 and 11, not shown) and the resultant recording made on a sheet (Fig. 11) or a CRT which may have a short persistence screen which is photographed, a long persistence screen or may be an electronic storage tube (Fig. 12). In these embodiments, the movement of the body 1 is also resolved and taken account of in the recording. In the Fig. 13 embodiment, the probe position and direction are detected by using spark generators 59, 60 on the probe 4 and an arm attached thereto which extends over the beam 5 axis. Linear microphones 57, 58 detect the noise generated by the sparks and apparatus 64 determines the four co-ordinates. These are passed to CRT 50 which shows the indication axis 11 and the CRT trace follows this axis and records echoes 8 to build up the composite picture 10. The apparatus is stated to be useful in flaw detection or medical diagnosis. By altering the spacing between the markers, the composite picture 10 can be scaled up or down as required. Reference has been directed by the Comptroller to Specification 1,326,898.