Experimental demonstration of phase-only circular harmonic filtering using computer generated filters.

Experimental results of phase-only circular harmonic filtering implemented in a standard Fourier transform correlator are presented. The filter is a computer generated hologram which contains only the phase information of a single circular harmonic component of the target. The result with simple binary objects bears out the simulation result published earlier [H. F. Yau and C. C. Chang, Appl. Opt. 28, 2070-2074 (1989)] in that the filter is indeed shift- and rotational-invariant and that the correlation peak is more prominent than that produced by ordinary circular harmonic filtering.