MATLAB Implementation of Detour Phase Holograms

Detour phase holography is a diffraction-based optical imaging technique that utilizes phase modulation, offering higher diffraction efficiency and better light energy utilization compared to traditional amplitude-type holograms. The core principle involves calculating the interference phase distribution between object waves and reference waves to generate phase-only holograms for light field reconstruction.

The MATLAB implementation of detour phase holograms primarily consists of the following steps:

Input Image Preprocessing: The target image must first be converted to appropriate grayscale format and resolution-adjusted to meet hologram computation requirements. Typically, images require normalization and may incorporate filtering operations (using functions like imfilter or fspecial) to optimize phase distribution.

Phase Computation: Based on Fourier transform (using fft2/ifft2 functions) or Fresnel diffraction theory, calculate the complex amplitude distribution of the input image. Phase information is extracted through angle() function, combined with reference wave phases (typically plane or spherical waves) to generate interference phase maps.

Phase Quantization (Optional): For practical fabrication feasibility, continuous phase distributions can be quantized using 4-level or 8-level quantization (employing round() or floor() functions with appropriate scaling) to match actual phase modulation devices like Spatial Light Modulators (SLMs).

Detour Phase Encoding: This core step involves periodic phase folding using modulo operations (mod() function) or custom wrapping algorithms. The technique maintains optical reconstruction capability while achieving high diffraction efficiency with binary or limited phase levels through clever phase wrapping strategies.

Hologram Output and Verification: Generated holograms can be saved as image files using imwrite function. Reconstruction validation employs optical simulation methods like angular spectrum approach (via conv2 or custom propagation functions) or actual optical experiments. Quality holograms should clearly reconstruct original images with high signal-to-noise ratio and light utilization efficiency.

This MATLAB implementation prioritizes computational efficiency in optical diffraction calculations and accuracy in phase encoding, ensuring excellent performance in both simulation and practical optical systems. The code is suitable for applications in optical information processing, holographic displays, and beam shaping technologies.