Browsing by Author "Singh, K"
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Anisotropic conical scattering in photorefractive BaTiO3: diffraction efficiency measurements
Joseph, J; Singh, K; Pillai, P K C (1991)The simultaneous presence of beam fanning and anisotropic conical scattering hinders the exact measurements on anisotropic conical diffraction. In this paper, a method is described for the measurement of diffraction ... 
Crystal orientation dependence of the SNR for signal beam amplification in photorefractive BaTiO3
Joseph, J; Singh, K; Pillai, P K C (1991)In signal beam amplification by twobeam coupling in BaTiO3 photorefractive crystals, beam fanning in the direction of the amplified signal reduces the signaltonoise ratio (SNR). The dependence of the SNR and the signal ... 
Higher order selfdiffraction in absorptive photorefractive medium; transmission geometry
Roy, Amitava; Singh, K (1992)Interactions between optical beams incident upon and two selfdiffracted beams generated within an absorptive photorefractive material are investigated by solving a set of coupled differential equations. The medium is ... 
Illumination sensitivity of joint transform correlators using differential processing:computer simulation and experimental studies
Pati, G S; Singh, K (1998)Differential and binary differential jointransform correlators are found to be associated with high tolerence to illumination variation of the reference and target.This makes them suitable for illumination independent ... 
An improved photorefractive jointtransform correlator utilizing beamfanning in a highgain barium titanate crystal
Pati, G S; Roy, Amitava; Singh, K (1996)A photorefractive nonlinear jointtransform correlator is demonstrated by utilizing the nonlinear intensitydependent behavior of beamfanning in a photorefractive barium titanate crystal. The results obtained reveal a ... 
Inplane displacement measurement using a photorefractive speckle correlator
Tripathi, Renu; Pati, G S; Arvind Kumar; Singh, K (1998)The present work describes the use of a photorefractive correlator in the measurement of inplane displacement. A correlation technique has been proposed and demonstrated for precise displacement measurement by recording ... 
Measurement of vibration with Young's fringe modulated speckle patterns in a photorefractive correlator
Dharmsaktu, K S; Arvind Kumar; Tripathi, Renu; Singh, K (2000)A technique has been proposed to analyze small inplane component of vibrations by measuring the fringe shift, and analysing the correlation output of captured vibrating Young's fringes with a photorefractive correlator. ... 
Multichannel image addition and subtraction using jointtransform correlator architecture
Pati, G S; Unnikrishnan, G; Singh, K (1998)A simple technique for multichannel image addition and subtraction has been proposed using a basic jointtransform correlator architecture. Computer simulation and experimental results are provided. The geometry can also ... 
A nonzero order joint transform correlator for spacevariant pattern recognition
Unnikrishnan, G; Joseph, Joby; Singh, K (1999)We propose a spacevariant correlator using a joint transform correlator JTC architecture. The reference and target images of a JTC are modulated by a random phase function which is the sample of a stationary white process ... 
On certain classes of exact solutions of einstein equations for rotating ﬁelds in conventional and nonconventional form
Bhutani, O P; Singh, K; Kalra, D K (2003)Using the symmetry reduction approach we have herein examined, under continuous groups of transformations,the invariance of Einstein exterior equations for stationary axisymmetric and rotating case, in conventional and ... 
On certain exact solutions of a generalized KdVBurger type equation via Isovector method I
Bhutani, O P; Singh, K (2000)A generalized KdVBurger type equation ut+a(u)+B(u)uxg(x)u=0 where m, n, p, q, a, a, b are constants and g(x) is an arbitrary function, has been analyzed through isovectors method. After constructing the components of ... 
Pattern discrimination using wavelet filters in a photorefractive jointtransform correlator
Tripathi, Renu; Joseph, Joby; Singh, K (1997)We propose and demonstrate the use of wavelet filters for pattern discrimination in a photorefractive (PR) jointtransform correlator. A PR BaTiO3 crystal has been used to record the joint power spectrum in realtime. ... 
Performance of a wavelet matched filter with optimized dilation designed using simulated annealing algorithm
Pohit, M; Singh, K (2001)We outline a method, using simulated annealing algorithm, to optimize the dilation factor of the wavelet function, from a number of images. The optimized dilation factor has been used to obtain wavelet matched filters ... 
Photorefractive halfadder: beamfanning for optical generation of ‘SUM’ and ‘CARRY’
Kamra, Kanwal; Singh, K (1996)Optical implementation of an adder of arithmetic units that processes binary numbers is outlined. Dynamic range compression using biasing illumination in beamfanning geometry as observed in a photorefractive BaTiO,:Fe ... 
Photorefractive jointtransform correlator using incoherenterasure in twowavemixing geometry
Pati, G S; Tripathi, Renu; Singh, K (1998)We propose and investigate a hotorefractive jointtransform correlator that uses an incoherent erasure beam in a twowavemixing arrangement. Computer simulation and experimental results are presented showing its performance ... 
A polarization encoded optical encryption system using ferroelectric spatial light modulator
Unnikrishnan, G; Pohit, M; Singh, K (2000)We discuss the principle, and experimentally demonstrate an optical encryption system that uses the polarization of light to encrypt a binary image. The encryption is done by an exclusiveOR (XOR) operation between the ... 
Spatial amplification via photorefractive twobeam coupling; realtime image processing using controllable erasure of Fourier spectrum
Joseph, Joby; Singh, K; Pillai, P K C (1991)A realtime image processing technique has been described, using a twobeam coupling geometry in photorefractive materials. An erase beam copropagating with the signal beam allows spatial amplification of selected frequency ... 
Stability improvement in bleached phase holograms
S kumar; Singh, K (1991)An experimental study has been made of the influence of developer composition on the stability against the printout effect of bleached, photographically recorded twobeam interference grating on AgfaGevaert 10E75 NAH ...