Analysis of a joint transform correlator using a phase-only spatial light modulator

Johnson, Francis; Barnes, Thomas H.; Eiju, Tomoaki; Haskell, T. G.; Matsuda, Kiyofumi

doi:10.1117/12.56011

Cited by 17 publications

(4 citation statements)

References 15 publications

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“…One of the main problems is the presence of a strong zero-order peak in the output plane that corresponds to the sum of the autocorrelations of the reference and input images and always overlaps the desired correlation signals. 3,4 For a single noise-free input, for example, the zero-order peak is at least four times stronger than the first-diffraction-order peak ͑matched correlation peaks͒. This situation becomes more serious in the presence of noise in the input scene.…”

Section: Introductionmentioning

confidence: 96%

Cosine wave encoded joint transform correlation

et al. 1996

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A cosine wave encoded joint transform correlation is proposed that can deliver excellent correlation performance in the presence of nonoverlapping noise or additive noise, and guarantee that the optical gain is less than unity-facilitating implementation. The method proposed uses three CCDs to capture the power spectra of the joint image, the reference-only image, and the input scene, and then extracts the cosine wave information of the joint power spectrum using simple subtraction and division operations. The extracted cosine wave information is encoded onto the input SLM of the second optical setup, resulting in a high optical efficiency. The cosine wave encoded joint transform correlation is found to be similar to even-function correlations between the phase-only Fourier-plane information of the reference and input images, which resembles the correlation of the phase-only input scene information with the phase-only filter using a reference image in the VanderLugt correlation arrangement. Computer simulations show that the cosine wave encoded joint transform correlation outperforms binary joint transform correlation when the targets are embedded in either nonoverlapping noise or scenes with additive noise; performance is maintained even when the target has a very low light contrast ratio in a severely noise-corrupted input scene.

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Section: Introductionmentioning

confidence: 96%

Cosine wave encoded joint transform correlation

et al. 1996

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“…In a previous work the , Johnson et al 12 analyzed the performance of a JTC in which the joint transform intensity distribution is converted onto a phase distribution before being inputted to the second Fourier transform system. As for Vander Lugt phase only filters, the system proposed by Johnson et al 12 improves the light efficiency and so the discrimination capability, however with multiple test objects they show that multiple output peaks appears due to nonlinearities in the system, and some of those peaks might be false alarms. The same result was obtained for the case of binarization nonlinearities in the JTC Fourier plane 13 .…”

Section: Introductionmentioning

confidence: 99%

Nonlinear optical time sequential correlations using phase input encoding

et al. 2004

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The presentation of nonlinear optical correlations using a joint transform correlator operating in phase-only spatial light modulation at input joint transform plane is studied here. Amplitude input nonlinear optical time sequential correlations have better discrimination and noise robustness than conventional linear correlations. These nonlinear correlations are based on decomposing reference and target into binary slices and adding the contribution of all linear correlations between them. Those correlations are implemented using a conventional joint transform correlator. However as the system has poor efficiency and low cross-correlation peak intensity working in amplitude mode, we use a phasetransformed input joint transform correlator in order to increase that efficiency and discrimination. We implement optically the phase morphological correlation and the phase sliced orthogonal nonlinear generalized correlation. We have applied the method to images degraded with high levels of substitutive noise and nonoverlapping background noise. The obtained results show how those nonlinear phase input encoded correlations have high discrimination capability detecting the target in cases where other well-known methods fail.

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“…On the other hand, a JTC can be operated at video frame rates 3 , and does not require a priori fabrication of a complex filter and meticulous alignment along the optical axis. Although a classical JTC provides attractive advantages over matched filter-based correlators 4 , it suffers from low diffraction efficiency, broad correlation width and discrimination sensitivity [5][6][7][8][9] . A binary JTC has been found to be superior to a classical JTC 5,9 .…”

Section: Introductionmentioning

confidence: 99%

Modified phase-encoded fringe-adjusted joint transform correlation for multiple target detection

et al. 2004

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A modified phase-encoded fringe-adjusted joint transform correlation technique is proposed for multiple target detection, where two joint power spectrums (JPS) are formulated utilizing a random phase mask and phase shifted random phase mask to the reference image separately. The final JPS is the difference between the phase encoded and shifted phase encoded JPS which is multiplied by the phase mask before applying the inverse Fourier transform to yield the correlation output. This technique ensures better utilization of the input/output plane space bandwidth product by yielding one delta function like correlation peak for each desired target object and no peak for non-target objects. The proposed technique can effectively detect any number of targets from noise free or noisy input scenes without changing the system parameters and without any degradation of performance. Computer simulation results verify the performance of the proposed technique.

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Analysis of a joint transform correlator using a phase-only spatial light modulator

Cited by 17 publications

References 15 publications

Cosine wave encoded joint transform correlation

Cosine wave encoded joint transform correlation

Nonlinear optical time sequential correlations using phase input encoding

Modified phase-encoded fringe-adjusted joint transform correlation for multiple target detection

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