Rotation invariant target detection using a modified amplitude modulated hybrid optical circular harmonic joint transform correlator is proposed. In this technique, the reference images (i.e. the real and imaginary parts of the circular harmonic component), the disk-like local bias function and the target image are displayed simultaneously in the input plane. The joint power spectrum is firstly modified by the subtraction of the power spectra of the input-scene-only (with local bias function) as well as of the reference image (with local bias function) and by the addition of the power spectrum of the local bias function from it. Then the resultant modified joint power spectrum is multiplied by the amplitude modulated filter function. The technique is found to yield a better correlation output than a classical circular harmonic joint transform correlator does. Computer simulation results and hybrid optical experimental results are given.