scholarly journals Optical Image Encryption Using a Nonlinear Joint Transform Correlator and the Collins Diffraction Transform

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 115 ◽  
Author(s):  
Juan M. Vilardy O. ◽  
Ronal A. Perez ◽  
Cesar O. Torres M.
Keyword(s):  
Fourier Transforms ◽  
Lateral Displacement ◽  
Random Phase ◽  
Design Parameters ◽  
Invariance Property ◽  
Joint Transform Correlator ◽  
Optical Processing ◽  
Optical Wave ◽  
Special Cases ◽  
Nonlinear Joint

The Collins diffraction transform (CDT) describes the optical wave diffraction from the generic paraxial optical system. The CDT has as special cases the diffraction domains given by the Fourier, Fresnel and fractional Fourier transforms. In this paper, we propose to describe the optical double random phase encoding (DRPE) using a nonlinear joint transform correlator (JTC) and the CDT. This new description of the nonlinear JTC-based encryption system using the CDT covers several optical processing domains, such as Fourier, Fresnel, fractional Fourier, extended fractional Fourier and Gyrator domains, among others. The maximum number of independent design parameters or new security keys of the proposed encryption system using the CDT increases three times in comparison with the same encryption system that uses the Fourier transform. The proposed encryption system using the CDT preserves the shift-invariance property of the JTC-based encryption system in the Fourier domain, with respect to the lateral displacement of both the key random mask in the decryption process and the retrieval of the primary image. The viability of this encryption system is verified and analysed by numerical simulations.

scholarly journals Image Encryption System Based on a Nonlinear Joint Transform Correlator for the Simultaneous Authentication of Two Users

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 128
Author(s):  
Juan M. Vilardy O. ◽  
María S. Millán ◽  
Elisabet Pérez-Cabré
Keyword(s):  
Image Encryption ◽  
Numerical Experiments ◽  
Random Phase ◽  
System Security ◽  
Fourier Domain ◽  
Brute Force ◽  
Joint Transform Correlator ◽  
Digital Fingerprint ◽  
Nonlinear Joint ◽  
Digital Fingerprints

We propose a new encryption system based on a nonlinear joint transform correlator (JTC) using the information of two biometrics (one digital fingerprint for each user) as security keys of the encryption system. In order to perform the decryption and authentication in a proper way, it is necessary to have the two digital fingerprints from the respective users whose simultaneous authentication is pursued. The proposed security system is developed in the Fourier domain. The nonlinearity of the JTC along with the five security keys given by the three random phase masks and the two digital fingerprints of the two users allow an increase of the system security against brute force and plaintext attacks. The feasibility and validity of this proposal is demonstrated using digital fingerprints as biometrics in numerical experiments.

Characterization of an Optimized Nonlinear Joint Transform Correlator

1994 ◽  
Vol 41 (6) ◽  
pp. 1253-1261
Author(s):  
B.S. Lowans ◽  
B. Bates ◽  
R.G.H. Greer
Keyword(s):  
Joint Transform Correlator ◽  
Nonlinear Joint

Analysis of Interferometer with Micro-Mirror on Beam Splitting Cube

2021 ◽  
pp. 129-143
Author(s):  
L.N. Timashova ◽  
N.N. Kulakova
Keyword(s):  
Interference Pattern ◽  
Fourier Transforms ◽  
Design Parameters ◽  
Spherical Mirror ◽  
Topographic Map ◽  
Wave Surface ◽  
Beam Splitting ◽  
Concave Mirror ◽  
Part Surface ◽  
Wave Aberration

The control of the shape of the optical part surface by the interference method has become an integral part of the process of their shaping. With a precisely focused interferometer interferometry allows obtaining an interference pattern similar to a topographic map of the error profile of the wave surface under investigation. The interferometer must form a map of the optical surface with high accuracy --- the permissible distortion of the interference fringe caused by an interferometer error should not exceed 0.1 of the distortion value caused by an error on the examined surface. The dependence of the interference pattern formation on the errors in the arrangement of the interferometer components, i.e., defocusing, was theoretically analyzed using Fourier transforms. The analysis was performed for an interferometer containing a laser illuminator, a concave spherical mirror with a central hole, coaxial to the illuminator, and a beamsplitting element in the form of a cube-prism with a semitransparent hypotenuse face. On the first flat face of the cube-prism, a microspherical concave mirror is made with the center located on the optical axis of the interferometer. A method for calculating the defocusing of a controlled spherical mirror and the corresponding wave aberration of the working wavefront is presented. An example of calculating the design parameters of the interferometer and the permissible defocusing of the controlled spherical mirror is given

scholarly journals Thermal Disturbances in Twinned Orthotropic Thermoelastic Material

2018 ◽  
Vol 23 (4) ◽  
pp. 897-910 ◽  
Author(s):  
L. Rani ◽  
V. Singh
Keyword(s):  
Fourier Transforms ◽  
Crystallographic Axis ◽  
Physical Domain ◽  
Matrix Differential Equation ◽  
Special Cases ◽  
Eigen Value ◽  
Basic Equations ◽  
Matrix Differential ◽  
Thermally Conducting ◽  
Vector Matrix

Abstract This paper deals with deformation in homogeneous, thermally conducting, single-crystal orthotropic twins, bounded symmetrically along a plane containing only one common crystallographic axis. The Fourier transforms technique is applied to basic equations to form a vector matrix differential equation, which is then solved by the eigen value approach. The solution obtained is applied to specific problems of an orthotropic twin crystal subjected to triangular loading. The components of displacement, stresses and temperature distribution so obtained in the physical domain are computed numerically. A numerical inversion technique has been used to obtain the components in the physical domain. Particular cases as quasi-static thermo-elastic and static thermoelastic as well as special cases are also discussed in the context of the problem.

scholarly journals Digital optical processing of optical communications: towards an Optical Turing Machine

Nanophotonics ◽  
2017 ◽  
Vol 6 (3) ◽  
pp. 507-530 ◽  
Author(s):  
Joe Touch ◽  
Yinwen Cao ◽  
Morteza Ziyadi ◽  
Ahmed Almaiman ◽  
Amirhossein Mohajerin-Ariaei ◽  
...  
Keyword(s):  
Computational Models ◽  
Optical Computing ◽  
Data Representation ◽  
Optical Processing ◽  
Hop Count ◽  
Optical Wave ◽  
Optical Computation ◽  
Combine Phase ◽  
Permanent Storage ◽  
Power Restoration

AbstractOptical computing is needed to support Tb/s in-network processing in a way that unifies communication and computation using a single data representation that supports in-transit network packet processing, security, and big data filtering. Support for optical computation of this sort requires leveraging the native properties of optical wave mixing to enable computation and switching for programmability. As a consequence, data must be encoded digitally as phase (M-PSK), semantics-preserving regeneration is the key to high-order computation, and data processing at Tb/s rates requires mixing. Experiments have demonstrated viable approaches to phase squeezing and power restoration. This work led our team to develop the first serial, optical Internet hop-count decrement, and to design and simulate optical circuits for calculating the Internet checksum and multiplexing Internet packets. The current exploration focuses on limited-lookback computational models to reduce the need for permanent storage and hybrid nanophotonic circuits that combine phase-aligned comb sources, non-linear mixing, and switching on the same substrate to avoid the macroscopic effects that hamper benchtop prototypes.

Analysis of a Pot-Like Ultrasonic Sensor with an Anisotropic Beam Pattern

2010 ◽  
Vol 26 (3) ◽  
pp. 373-384 ◽  
Author(s):  
C.-C. Cheng ◽  
C.-Y. Lin ◽  
J.-H. Ho ◽  
C.-S. Chen ◽  
J. Shieh ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Fourier Transforms ◽  
Numerical Models ◽  
Beam Width ◽  
Ultrasonic Sensor ◽  
Beam Pattern ◽  
Design Parameters ◽  
Far Field ◽  
Vertical Beam ◽  
Vibrating Plate

AbstractWe investigated the design parameters of a compact pot-like ultrasonic sensor which possesses a highly anisotropic beam pattern. As the sensor size is small due to its application constraint, the parameters are thus highly coupled to one another. We analyzed the respective effects of the parameters in the case where there is a vertical beam width reduction. The parameters investigated include resonant frequency, vibrating plate width-expanded angle, and ratio of thickness discontinuity of the vibrating plate. Numerical models developed by combining finite-element analysis and spatial Fourier transforms were adopted to predict the far-field radiating beam pattern of the various design configurations. The displacement distribution of the vibrating plate was measured using a microscopic laser Doppler vibrometer and the far-field pressure beam patterns were measured using a standard microphone in a semianechoic environment. The three configurations we used to validate the simulation model resulted in an H-V ratio of 2.67, 2.68 and 3.13, respectively which all agreed well with the numerical calculations. We found that by increasing the operating resonant frequency from 40kHz to 58kHz, the vertical far-field beam width of an ultrasonic sensor can be reduced by 31.62%. We found that the vertical beam width can be significantly reduced when the ratio of the thickness discontinuity of the vibrating plate decreases from 1 to 0.4 and is incorporated with its optimal width-expanded angle of the vibrating plate. It appears that an ultrasonic sensor with this type of anisotropic beam pattern can be ideally adopted for today's automotive applications.

Analysis of the Nonlinear Dynamics of a Railway Vehicle Wheelset

1973 ◽  
Vol 95 (1) ◽  
pp. 28-35 ◽  
Author(s):  
E. Harry Law ◽  
R. S. Brand
Keyword(s):  
Lateral Displacement ◽  
Equations Of Motion ◽  
Vertical Displacement ◽  
Linear Analysis ◽  
Design Parameters ◽  
Railway Vehicle ◽  
Nonlinear Variation ◽  
Constraint Equations ◽  
The Stability ◽  
Nonlinear Equations Of Motion

The nonlinear equations of motion for a railway vehicle wheelset having curved wheel profiles and wheel-flange/rail contact are presented. The dependence of axle roll and vertical displacement on lateral displacement and yaw is formulated by two holonomic constraint equations. The method of Krylov-Bogoliubov is used to derive expressions for the amplitudes of stationary oscillations. A perturbation analysis is then used to derive conditions for the stability characteristics of the stationary oscillations. The expressions for the amplitude and the stability conditions are shown to have a simple geometrical interpretation which facilitates the evaluation of the effects of design parameters on the motion. It is shown that flange clearance and the nonlinear variation of axle roll with lateral displacement significantly influence the motion of the wheelset. Stationary oscillations may occur at forward speeds both below and above the critical speed at which a linear analysis predicts the onset of instability.

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