Incoherent optical image encryption based on coded aperture correlation holography

We propose an incoherent encoding system for image encryption utilizing the coded aperture correlation holography (COACH) technique. Incoherent imaging is the core component of this proposal, in which the point spread hologram (PSH) of the imaging system serves as the main key to encode the input intensity distribution. The proposal makes full use of PSH which consists of four point spread functions (PSFs) respectively generated by four coded phase masks (CPMs), so that a multidimensional key space is generated to resist illegal attacks. Incoherent illumination of the imaging system ensures that only the intensity information is manipulated. The encoded information is just an intensity distribution which is advantageous for data storage, simplifying the system structure and processing, and suppressing the information expansion involved in general conventional encryption methods. Both numerical and experimental results illustrate the feasibility and effectiveness of the proposed method. This work represents an effective idea for incoherent optical encryption techniques.