High-Power, High-Brightness Beam Combination of Semiconductor Lasers using Multiple Gratings in a High Efficiency Thick Hologram

Period of Performance: 04/28/2000 - 04/09/2001


Phase 1 SBIR

Recipient Firm

Digital Optics Technologies, Inc.
64 Daly Dr. Ext
Stoughton, MA 02072
Principal Investigator


We propose to use a thick holographic memory disc (HMD) to demonstrate an optical image correlator which has the potential to identify an object from a set of 8 million images in less than 1 msec. The storage capacity of this HMD can exceed 1 terabyte, so that each image can have a high resolution: 1000 bits X 1000 bits. One key element of this proposal is a novel material we have developed. Termed Photopolymer with Diffusion Amplification (PDA), this material can be prepared in almost any size and thickness, and is immune from the problem of differential shrinkage. Furthermore, it can be produced with quartz-like optical quality, has a high diffraction efficiency over a wide range of wavelengths (488 nm to 2000 nm), and does not suffer from absorption. We have observed a very high dynamic range, so that more than 1000 holographic images can be multiplexed in a single spot. Previously, we have demonstrated storage and recall of a video clip in this material; the restored images are virtually identical to the stored ones. The other key element of the proposal is a novel architecture that allows a massively parallel enquiry of all the individual storage subareas in the whole disc. The correlator can be used to identify hostile elements such as missiles, planes, and tanks, very rapidly. The massive storage capacity ensures that many orientations and scales of a single object can be stored, so that the object can be identified under many different conditions of observation. This is of direct interest to DOD in general, and BMDO in particular. Other dual use applications include computer vision, data base search in video archives, fingerprint-identification, and so on.