Ultrasonic inspection devices

by m o r e than a p r e d e t e r m i n e d amount, the amplitudes of ultrasonic signals of two different c a r r i e r frequencies transmitted in turn through the object are c o m puted, the frequencies being selected such that only one propagates through the object if the structure differs by m o r e than the p r e d e t e r m i n e d amount. In embodiments for investigating grain size in steel, graphite inclusions in cast iron, relative content of alpha and g a m m a phases in stainless steels, o r composition of plastics etc, a transmitting t r a n s d u c e r is pulsed by a switched-frequency rf oscillator and a receiving t r a n s d u c e r feeds the reply signals through a calibrated attenuator to deflection-modulate a crt display. Ultrasonic holography Holotron Corp British Patent 1,200, 948 (1970) Ultrasonic holograms from which multiple images, in different colours, of an object can be r e c o n s t r u c t e d are f o r m e d by directing ultrasonic energy including at least two distinct ultrasonic frequencies via the object to a hologram-detecting surface in a fluid medium and also directly to the detecting surface, the two frequencies of the d i r e c t l y - t r a n s m i t t e d energy being respectively coherent with the two frequencies of the energy transmitted via the object. In an embodiment for detecting internal tumours in the body f r o m the relative opacities of the body to 3MHz and 9MHz ultrasound, 30btm pulses are applied alternately at 500ps intervals to the two t r a n s d u c e r s to provide reference and object b e a m s which interfere to give two different standing wave patterns (holograms) in the water surface. Collimated light f r o m a m e r c u r y a r c source is diffracted by the standing waves into beams which are focused in different points according to the ultrasonic frequency and light wavelength. Only two of the beams pass through an apertured mask to provide a two-colour image when viewed. The image is scanned by a Vidicon tube.

Acoustic direction-finding Honeywell Inc British Patent 1,201,218 (1970)

Acoustic direction-findlng Honeywell Inc British Patent 1,201,220 (1970) An acoustic direction-finding system c o m p r i s e s an underwater t r a n s m i t t e r emitting trains of waves, each train having a pulse component and a continuous wave component, two p a i r s of hydrophones in one plane, and means for computing the differences in times of a r r i v a l of the pulse component and the diff e r e n c e s in phases of the continuous wave components. Ultrasonic probes: ultrasonic inspection devices Stewarts ~ Lloyds Ltd British Patent 1,201,261 (1970) An ultrasonic jet probe has a main irrigation channel aligned with an ultrasonic t r a n s d u c e r and extending t h e r e f r o m to direct liquid onto an article under test, and an auxiliary irrigation s y s t e m for supplying liquid to at least one side of the s t r e a m of liquid from the main irrigation channel. Liquid is supplied by way of the ultrasonic t r a n s d u c e r into the main irrigation channel, whereas liquid supplied to the auxiliary irrigation s y s t e m does not contact the transducer. 126

ULTRASONICS April 1971

Acoustic ranging devices: reflectors Longden, D. M. (L. S. Services) British Patent 1,201,509 (1970) Ultrasonic inspection devices Vsesojuzny Nauchno-Issledovatelsky Institut po R a z r a b o t k e Nerazrushajuschikh Metodov I Sredstv Kontrolya Kachestva Materialov British Patent 1,201,678 (1970) In an ultrasonic pulse instrument for testing m a t e r i a l s by measuring propagation velocity, r e v e r b e r a t i o n time, and the period of the main travelling wave, a calibrator is provided for checking the calibration of a variable delay unit used in conjunction with a crt to m e a s u r e propagation time. An ultrasonic pulse is sent through the test m a t e r i a l by a piezoelectric transducer, and received by a similar transducer, whose output is amplified to the crt and a detector. A delay unit is adjusted initially to give coincidence between the signal at the receiving t r a n s d u c e r and the s t a r t of crt sweep. Propagation time m e a s u r e m e n t s a r e made by adjusting two other delay units to give coincidence again when the material is in place.

Acoustic measurement of physical properties Compagnie des Compteurs British Patent 1,202, 281 (1970) In determining the physical p r o p e r t i e s of a gas, oscillations a r e maintained in a gas-filled resonant cavity having a neck-shaped opening by means of acoustic feedback between an energising t r a n s d u c e r and a pick-up transducer. Ultrasonic inspection devices Automation Industries Inc British Patent 1,202, 376 (1970) To determine the position of an acoustical target in an object, ultrasonic t r a n s d u c e r s coupled to the object are operated in three modes to provide respective range m e a s u r e m e n t s which are compared automatically on a numerical display device. In the embodiment for detecting any displacements of the brain midline from the centre of a skull, ' r i g h t ' and 'left' probes are operated sequentially in through-transmision, right pulse-echo and left pulse-echo modes. The ramp voltages for the three modes are sorted and passed to corresponding peak detectors. If the brain midline is central, the travel t i m e s of ultrasonic pulses reflected from the midline or transmitted through the skull will be equal, as will the peak voltages. Displacement of the midline will result in equal and opposite deviations of the voltages on the ' r i g h t ' and 'left' peak detectors from the voltage on the 'through' peak detector.

Electro-acotmtic t r - a n ~ h c e r s S. L. Heindrich British Patent 1,203,252 (1970)

Acoustic delay lines Singer Co British Patent 1,203,409 (1970)

Ultrasonic inspection devices Automation Industries Inc British Patent 1,203,854 (1970) Apparatus for inspecting a work-piece such as a weld c o m p r i s e s a t r a n s d u c e r for transmitting ultrasonic