Effects of spatial light modulator opaque dead zones on optical correlation.

Each pixel of a spatial light modulator (SLM) consists of a phase- or amplitude-modulating area (the active zone) within an inactive area (the dead zone). Here we study optical correlators that contain input and filter SLM's whose dead zones are opaque. Computer simulations and analytical calculations are carried out for these correlators when a phase-only, a binary phase-only, or a classical matched filter is written on the filter SLM. The correlation signal-to-noise ratio for a particular filter is independent of a dead zone since its energy throughput is proportional to its peak correlation intensity.