Compensation for pixel misregistration in volume holographic data storage

Area of Science:

• Holographic data storage
• Optical data processing
• Image registration algorithms

Background:

• Holographic storage systems face challenges with precise alignment between detector arrays and data pages.
• Coherent illumination and square-law detectors introduce linear and quadratic signal distortions.
• Current systems require stringent constraints on optical distortion and material shrinkage.

Purpose of the Study:

• To introduce a novel postprocessing algorithm for compensating detector-image misregistrations in holographic storage.
• To relax the strict alignment and distortion tolerances in pixelated data page detection.
• To enhance the robustness and practicality of holographic data storage systems.

Main Methods:

• A lookup table of local offsets is combined with dynamic global offset measurements.
• A serial algorithm reallocates pixel signals to neighbors, correcting for lateral shifts.
• The algorithm accounts for linear and quadratic signal contributions from coherent illumination.

Main Results:

• The algorithm effectively compensates for misregistrations between detector arrays and coherent images.
• Experimental results show a significant increase in position tolerance from +/-16% to +/-40% of the pixel pitch.
• A raw bit-error rate below 10(-3) was maintained with the improved tolerance.

Conclusions:

• The developed postprocessing algorithm significantly enhances position tolerance in holographic storage systems.
• This method alleviates critical constraints on page registration and optical quality.
• The findings pave the way for more reliable and widely applicable holographic data storage solutions.