Balanced Opto-electronic Joint Transform Correlator for Enhanced Real-Time Pattern Recognition

Opto-electronic joint transform correlators (JTCs) use a focal plane array (FPA) to detect the joint power spectrum (JPS) of two input images, projecting it onto a spatial light modulator (SLM) to be optically Fourier transformed. The JPS is composed of two self-intensities and two conjugate-products, where only the latter produce the cross-correlation. However, the self-intensity terms are typically much stronger than the conjugate-products, consuming most of the available bit-depth on the FPA and SLM. Here we propose and demonstrate, through simulation and experiment, a balanced opto-electronic JTC that electronically processes the JPS to remove the self-intensity terms, thereby enhancing the quality of the cross-correlation result.