Abstract: There is disclosed herein an ultrasonic imaging system for use in non-destructively testing objects, which system includes a source of ultrasonic energy, a liquid crystal detector cell and an optical viewing system. The liquid crystal detector cell includes a pair of acoustically transmissive covers which encase a nematic liquid crystal material. The material exhibits an acousto-optic effect, and in particular, exhibits birefringence in response to ultrasonic energy. The cell construction, geometry, and material are acoustically matched to the frequencies of the insonifying ultrasonic transducer so as to optimize the performance of the cell. The covers are substantially acoustically transparent to ultrasonic energy incident on the cover at both normal and oblique attitudes. The acoustic impedance of the covers match as closely as possible to that of the coupling medium.

Abstract: There is disclosed herein an acoustic or ultrasonic power meter which includes a liquid crystal cell for detecting acoustic energy and a control circuit for applying an electric field to said cell. The liquid crystal cell includes a liquid crystal material having elongated molecules. The preferred liquid crystal is in the form of a layer of the nematic type which is homeotropically aligned. The elongated liquid crystal molecules exhibit positive dielectric anisotropy wherein the dielectric constant parallel to the molecule's axis is greater than the dielectric constant perpendicular to the molecule's axis. In the unexcited condition, the nematic layer is dark. In the ultrasonically excited condition, the nematic layer exhibits birefringence. A restoring electric force can be applied to the liquid crystal material to suppress the acoustically-induced birefringence condition of the cell to the dark appearance associated with the unexcited condition.

Abstract: There is disclosed herein a method for producing a liquid crystal display or cell which has a liquid crystal film positioned between a pair of substrate members whose surfaces have been ultrasonically surface treated so as to cause the liquid crystal molecules to be aligned in a predetermined manner.The method includes ultrasonically treating the surface of the substrate which contacts the liquid crystal film so as to form microgrooves or striations. The surface is treated by immersing the substrate in a liquid bath, ultrasonically forming a column of cavitation bubbles which is directed to the substrate where the cavitation bubbles collapse on the substrate, and moving the substrate through the liquid at a predetermined speed so as to form microgrooves or striate the surface of the substrate. Using two such treated substrates, a liquid crystal cell is prepared in the form of a sandwich of substrate/liquid crystal/substrate.

Abstract: There is disclosed herein a portable device for inspecting bodies for internal flaws or other internal features. The device is constructed so as to be mounted on the surface of the body, emit and receive ultrasonic energy, and display the same on a liquid crystal display. The device includes a first housing member for supporting a transducer in relation to the surface being inspected. The device also includes a second housing member for supporting and positioning the liquid crystal display in relation to the surface and in relation to the transducer. Interconnecting means are provided for adjustably interconnecting the two members and fixing their positions in a reflection-receiving relation. The liquid crystal support housing is a substantially hollow tubular member having a viewing end and a surface contacting end. The liquid crystal display is positioned intermediate the ends.

Abstract: There is disclosed herein an ultrasonic system for detecting internal discontinuities in a body. The system includes: an ultrasonic transducer for directing sonic energy toward a body; a liquid crystal, acousto-optical detector cell for detecting ultrasonic energy passing through said body; an optical system for illuminating said liquid crystal cell; and a liquid medium for coupling the transducer body and cell.The acousto-optical cell includes a pair of substantially rigid covers, a liquid crystal material positioned between said covers and a peripheral spacer and sealing member surrounding said liquid crystal and sealingly engaging said covers. Each of the covers is substantially acoustically transparent and at least one of said covers is optically transparent. The optically transparent cover is a laminate having at least three layers, with each of said layers of said laminate having a thickness much much less than 1/4 of the wave length of the ultrasonic energy propagating through said layer.