Experiments are provided to investigate nonlinear joint transform correlator sensitivity to scaling and rotation changes of input objects for various degrees of nonlinearity applied to the joint power spectrum. The experimental results for the images used here show that a severe nonlinear transformation of the joint power spectrum increases the sensitivity of the correlation peak intensity to scaling and rotation changes of input objects. However, the correlation peak-to-sidelobe ratio of the nonlinear joint transform correlator remains higher than the linear joint transform correlator. These experiments indicate that, in the presence of input signal rotation or scale changes, the performance of the nonlinear joint transform correlator may be better than the linear joint transform correlator. The effect of the modulation transfer function of the spatial light modulator on the nonlinear joint transform correlator performance in the presence of multiple input targets is discussed.
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