Abstract: An acoustic imaging system which employs a liquid crystal cell for detecting acoustic energy and displaying an image. The cell includes a layer of liquid crystal material which is disposed between and encapsulated by a pair of cover members. At least one of the cover members is a laminated structure having at least two plies. The plies are of different materials and the thickness of each ply is governed by the expression n .lambda./2, where n is an integer, and .lambda. is the wavelength of the acoustic energy in the cover materials. This structure enhances cell rigidity and the uniform of thickness of the liquid crystal layer in larger sized cells, while maintaining good transmission for energy angularly incident on the cell.

Abstract: There is disclosed herein an apparatus and method for producing a substantially uniform acoustic field for use with a liquid crystal cell to produce a substantially artifact-free image of an object. The apparatus and method include moving an ultrasonic transducer toward and away from an object, a distance effective to cause adjacent constructive and destructive zone patterns to in effect overlie each other. The period of reciprocation is less than the time for onset of image decay, but greater than the image rise time so as to assure image formation. In addition, the frequency and/or phase of the acoustic energy can be varied so as to further enhance the image.Electro-mechanical and piston driven embodiments are disclosed for reciprocating the transducer.

Abstract: There is disclosed herein an ultrasonic imaging system using a liquid crystal detector cell and a source of non-coherent acoustic energy to produce substantially artifact-free images. The ultrasound source and cell are matched with one another, and the source is caused to operate over a range of frequencies or phases so as to produce the non-coherent ultrasonic energy. The frequency response of the cell and its response time are matched to the operating characteristics of the transducer. The transducer may be mounted in a pendulum-like sector scanning apparatus so as to assure a uniform insonification of the object, a uniform beam and a substantially uniform non-coherent insonification of the cell. The movement of the scanning apparatus is also matched to the cell and the transducer characteristics.

Abstract: There is disclosed herein an orthoscopic ultrasonic imaging system which includes an acoustic transducer for insonifying an object to be inspected and an improved liquid crystal detector cell for receiving an imaging beam from the insonified object and for displaying a visible image.An acoustic biasing field is applied to the liquid crystal cell for raising the cell to an acousto-optic threshold which permits detection and display of low intensity imaging signals. Using the improved liquid crystal system, low intensity, acoustic fields [e.g. less than 10.sup.-3 w/cm.sup.2 (watts per square centimeter)] can be detected and displayed, and the object being examined can be insonified with low intensity ultrasonic beams.

Abstract: There is disclosed herein a movable, ultrasonic transducer array for use in an ultrasonic inspection system that employs a signal detector and display of the liquid crystal cell type. The movable array uniformly insonifies the object to be inspected and is particularly suitable for inspecting large objects or large areas of an object. The array may include a plurality of sending or emitting transducers which are held in substantially parallel alignment so that their transmission or radiation axes are parallel. The array is part of an assembly which includes a support for holding the transducers and a drive system for moving the array and support along a predetermined path.In a first specific embodiment, the array is mounted on a support which moves along a circular path while maintaining the relative horizontal and vertical positions of the transducers. That movement is accomplished by use of a drive and linkage system which provides for an eccentric-like movement.