Super Parallel Holographic Optical Correlator for Rapid Identification of Targets (BMDO/02-211B: Optical Devices)

"In many situations, it is necessary to identify a target rapidly. Here, we offer to demonstrate a novel device that can search through more than ten million images, stored in a one terabyte holographic memory unit (HMU), in a millisecond. Called the superparallel holographic optical correlator (SPHOC), this device can be viewed as nearly two thousands holographic optical correlator (HOC) running in parallel. The key innovation here is a novel architecture we have developed and demonstrated, where thequery image is split into 1600 copies using a holographic multiplexer/demultiplexer (HMD). Each image is then applied to one of the 1600 sub-areas of the HMU, each storing nearly 8000 images that are angle-multiplexed in two dimensions. An HMD along withtwo detector arrays (one with 1600 elements, the other with 8000 elements) are used to decipher which, if any, image is matched. The SPHOC outperforms an HOC by nearly three orders of magnitude, and has an effective speed that is more than a million timesfaster than a digital signal processing based correlator. Many HMU's can be loaded serially to search through billions of images. The ability to access very rapidly such an enormous database, which could contain many views of each missile, would enableidentification and tracking of an incoming missile more efficiently than any existing technology. This technology is likely to revolutionize the field of image identification. For BMDO,