Comparative analysis of optical and hybrid joint transform correlators for security applications

The possibilities of using of optical and hybrid joint transform correlator (JTC) architectures for construction of security devices with usage of the transformed phase masks (PMs) as optical marks are investigated. With this purpose the yardsticks of an estimation of their efficiency, namely peak- to-noise ratio (PNR) and relative intensity of correlation peaks, are selected general for two types of JTCs. The idealized model of an interference noise in a linear JTC is designed, if the binary random PMs on input are entered. The relations of a PNR to dimension both PM and window ambient correlation peak are parsed. The optically addressed spatial light modulator (OASLM) based on the chalcogenide glass photoconductor -- nematic liquid crystal structure is studied. The experimental setup of an OASLM JTC is designed on the basis of this SLM. The relations a PNR and relative intensity versus an effective focal length are studied and the major factors limiting efficiency of the setup are parsed. The optoelectronic device based on a hybrid optical-digital JTC architecture is built. The relations to different conditions of a joint power spectrum recording by a CCD-camera in this device are investigated. The comparative analysis of two types of JTC is carried out also concluding about expediency of their usage for different security applications is made.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.