Design and performance of a joint transform correlator (JTC) system for measuring blood flow and tissue motion

Liquid crystal televisions (LCTVs) have recently become popular spatial light modulators. This paper describes in detail the design of a joint transform correlator (JTC) system that uses two inexpensive LCTVs obtained from a video projector. A prototype JTC system was used to measure blood flow and tissue motion in ultrasound speckle images. The design of spatial filters that allow real-time image processing of the ultrasound images are presented along with experimental results that characterize the improved performance. A novel spatial multiplexing technique that allows many flow vectors to be computed simultaneously is described. This spatial multiplexing technique can enhance the overall system vector throughput of a conventional JTC system by over a factor of 100. The prototype JTC system has the same tracking accuracy as the digital methods that are currently being used. In addition to speed, the JTC system offers advantages in cost, size, and power consumption.