Ultrasonic image conversion
AssigneeE M I Limited
InventorPatrick Harold Brown
Life of this patent
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Abstract
Ultrasonic imaging techniques are subject to interference from whiteout, a component at insonification frequency in the image signal. A technique for separating the image signal from whiteout by mixing the received ultrasonic radiation with another frequency is described. In one form using an electron beam to scan a transducer mosaic the beam is modulated and mixing occurs between the transducer and a signal plate. A filter connected to the signal plate selects a mixing product containing the image signal and rejects the insonification and beam frequencies.
Claims12
An ultrasonic image converter tube arrangement including a pick-up tube having, in an envelope, anode and cathode electrodes, an electron beam source and a scannable surface of a sensor plate with a capacitively coupled signal plate having an output terminal connected thereto, means to scan a beam from said source over said scannable surface, means to modulate the current in said scanned beam and, connected to said terminal, means selectively responsive to a frequency component resultant from the mixing of the beam current modulation signal and the signals representing an image in ultrasonic radiation scanned off the sensor plate which image, in operation of the arrangement, is incident on said sensor plate in ultrasonic radiation, the selectively responsive means rejecting components at the frequency of said ultrasonic radiation.
A method of detecting variations of ultrasonic radiation representing an image in ultrasonic radiation incident upon a two-dimensional sensor including
- providing a source of another frequency of a value distinct from the ultrasonic radiation frequency value,
- applying the another frequency and the ultrasonic frequency to a non-linear means in the sensor to produce mixing products including at least one modulated by said variations
- filtering a single mixing product modulated by said variations from other mixing products, including any at said ultrasonic frequency, whereby said variations are obtained as a time-based signal substantially without any component at the ultrasonic frequency.
Dependencies are inferred from the claim text.