Integration of a PQ:PMMA holographic memory device into the hybrid opto-electronic correlator for shift, scale, and rotation invariant target recognition

Abstract

The hybrid optoelectronic correlator (HOC) combines optical and electronic signal processing to achieve the same functionality as traditional optical correlators but without the need for dynamic materials. Here we propose and demonstrate the integration of a PQ:PMMA holographic memory device (HMD) into the HOC as a high-speed all-optical database for reference images. Using a PQ:PMMA HMD for one of the inputs eliminates one of the key speed limitations in the HOC. The observed correlation signal agrees with simulations but highlights the need for high quality holographic substrates in this application.

Optical Correlators for Cryptosystems and Image Recognition: A Review

“…An experimental setup was developed, including a DPSS laser, a beam splitter, piezoelectric transducers, a Mach–Zehnder interferometer, photodetectors and a PID (Proportional-Integral-Differential) controller, and validated the efficiency and accuracy of recognition with the proposed method. To further improve the operational speed of the correlator, the same group [ 121 , 122 ] proposed the use, as optical storage database of high capacity, a holographic memory device (HMD) based on the polymer substrate PQ:PMMA (Phenanthrenequinone-doped poly(methyl methacrylate)), and experimentally validated the feasibility and efficiency of introducing, in the HOC correlator, the PQ:PMMA HMD. Monjur et al [ 8 ] validated, by means of experiments, the functioning principle of a HOC correlator previously proposed by the same group.…”

“…Although the HOC correlator has recently achieved correlation with invariance to rotation, scale and position, future developments are aimed towards its complete automation for an operation in real-time. The speed is envisioned to be further improved, up to an ideal value of approximately 5 μs per correlation, using optoelectronic integrated circuits, customized for this type of correlator [ 121 ]. Another enhancement for the HOC correlator, proposed by Monjur et al [ 8 ], was to include a new component, not yet developed, named the IGPU (Integrated Graphic Processing Unit) that enables an increase of the speed such that a correlation operation could be performed in only several microseconds, by avoiding the considerable slowing down due to serial communications between SLMs, FPGAs (field programmable gate arrays), cameras and other components of the correlator setup.…”

Optical Phase Insensitive Off-axis Operation of the Hybrid Opto-electronic Correlator for Ultra-fast Shift, Scale, and Rotation Invariant Target Recognition

“…This correlator can theoretically operate at speeds on the microsecond scale but is limited by the availability of high-speed SLMs to project the query images into the optical domain. As such, holographic memory devices (HMDs) can be employed as all-optical databases of reference images within the HOC, eliminating the need for ultrafast SLMs [5]. Additionally, we have recently eliminated the requirement for optical phase stabilization in this architecture through the use of an off-axis technique, removing perhaps the largest practical limitation of this technology [6].…”