Browsing Electrical, Electronic and Communications Engineering Research Collection by Author "Situ, Guohai"

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Browsing Electrical, Electronic and Communications Engineering Research Collection by Author

Browsing Electrical, Electronic and Communications Engineering Research Collection by Author "Situ, Guohai"

Now showing items 1-6 of 6

Cryptanalysis of optical security systems with significant output images

Situ, Guohai ; Gopinathan, Unnikrishnan ; Monaghan, David S. ; Sheridan, John T. (Optical Society of America, 2007-08-01)

The security of the encryption and verification techniques with significant output images is examined by a known-plaintext attack. We introduce an iterative phase-retrieval algorithm based on multiple intensity measurements ...
Generalized in-line digital holographic technique based on intensity measurements at two different planes

Situ, Guohai ; Ryle, James P. ; Gopinathan, Unnikrishnan ; Sheridan, John T. (Optical Society of America, 2008-02-10)

In-line digital holography based on two-intensity measurements [Zhang et al. Opt. Lett. 29, 1787 (2004)], is modiﬁed by introducing a π shifting in the reference phase. Such an improvement avoids the assumption that the ...
Holography : an interpretation from the phase-space point of view

Situ, Guohai ; Sheridan, John T. (Optical Society of America, 2007-12-15)

The formation of holograms is interpreted as the consequence of the bilinearity of the ambiguity function. Reconstruction can then be regarded as the manipulation of the ambiguity function. Specifically, we show that in ...
Noninterferometric phase retrieval using a fractional Fourier system

Gopinathan, Unnikrishnan ; Situ, Guohai ; Naughton, Thomas J. ; Sheridan, John T. (Optical Society of America, 2008-01-01)

The signal extraction method based on intensity measurements in two close fractional Fourier domains is examined by using the phase space formalism. The fractional order separation has a lower bound and an upper bound that ...
Role of phase key in the double random phase encoding technique : an error analysis

Monaghan, David S. ; Situ, Guohai ; Gopinathan, Unnikrishnan ; Naughton, Thomas J. ; Sheridan, John T. (Optical Society of America, 2008-07-20)

We perform a numerical analysis of the double random phase encryption–decryption technique to determine how, in the case of both amplitude and phase encoding, the two decryption keys (the image- and Fourier-plane keys) ...
Statistical investigation of the double random phase encoding technique

Monaghan, David S. ; Gopinathan, Unnikrishnan ; Situ, Guohai ; Naughton, Thomas J. ; Sheridan, John T. (Optical Society of America, 2009-08-24)

The amplitude-encoding case of the double random phase encoding technique is examined by deﬁning a cost function as a metric to compare an attempted decryption against the corresponding original input image. For the case ...