The phase-space description of signals is a joint space-spatial frequency representation in local domain.
It employ the phase-space representation functions to describe the property of optical signals between
two variables that form a Fourier transform pair and provide a valuable analysis tool for signals when
this new mathematical analysis tool applied to an optical system. This method can also be applied to
the analysis of propagation of laser beam within free space or atmosphere condition. In this paper, we
give the analytical formula of optical field distribution of laser beam after propagation within
turbulence in the domain of phase-space. The results show an instructing aspect of optical signal
propagation and are helpful to the future application of phase-space method to the laser
communications.
Fresnel telescopy full-aperture synthesized imaging ladar is a new high resolution active laser imaging technique. In the
operational mode with moving target by beam scanning, spatial distributions of the complex data of the returned signals
are not regular or uniform. In order to use fast Fourier transform (FFT) algorithm in signal processing, algorithm for
Fresnel telescopy imaging system should include resampling interpolation step to change sampling data into uniform and
quadratic spatial distribution. We choose suitable resampling interpolation algorithm for Fresnel telescopy, and get
computer simulation of area target. The work is found to have substantial practical value and offers significant practical
benefit for high resolution imaging in Fresnel telescopy imaging ladar.
An efficient technique of utilizing Dammann grating and phase plate to get high power and high brightness laser beam
from phase-locked laser array is presented. The conjugate Dammann grating and the phase plate are placed in the back
and front focal plane of a Fourier lens respectively. In order to improve the beam combining efficiency, Continuous
grating of high diffraction efficiency is used to replace the Dammann grating. Analysis shows that the Continuous
grating which has a higher diffraction of efficiency is also suitable for beam combining of the presented system.
Fresnel telescopy (short for Fresnel telescopy full-aperture synthesized imaging ladar) is a new high resolution active
laser imaging technique. This technique is a variant of Fourier telescopy and optical scanning holography, which uses
Fresnel zone plates to scan target. Compare with synthetic aperture imaging ladar(SAIL), Fresnel telescopy avoids
problem of time synchronization and space synchronization, which decreasing technical difficulty. In one-dimensional
(1D) scanning operational mode for moving target, after time-to-space transformation, spatial distribution of sampling
data is non-uniform because of the relative motion between target and scanning beam. However, as we use fast Fourier
transform (FFT) in the following imaging algorithm of matched filtering, distribution of data should be regular and
uniform. We use resampling interpolation to transform the data into two-dimensional (2D) uniform distribution, and
accuracy of resampling interpolation process mainly affects the reconstruction results. Imaging algorithms with different
resampling interpolation algorithms have been analysis and computer simulation are also given. We get good
reconstruction results of the target, which proves that the designed imaging algorithm for Fresnel telescopy imaging
system is effective. This work is found to have substantial practical value and offers significant benefit for high
resolution imaging system of Fresnel telescopy laser imaging ladar.
In order to study the influence of the time-varying turbulence to facular orientation precision when the facula is moving
during the pointing and tracking process, a random phase screen is generated using modified inverse fourier transform to
simulate atmospheric turbulence. And then the orientation deviation of the facular barycenter, the relation between the
deviation and the facular position in the detector and the orientation precision of the facula is analyzed under different
atmospheric turbulence intensity. The results indicate that at the presence of time-varying atmospheric turbulence, there
is a deviation between actual translational amount of the facular barycenter and that of the barycenter detected by the
charge-coupled device and it relates with the atmospheric turbulence intensity. And the dynamic facular orientation
precision is found that it relates to the atmospheric turbulence intensity and the facular position in the detector.
A new method of high resolution laser imaging is developed in this paper, which is denoted as Fresnel telescopy. It
creates Fresnel zone plate (FZP) fringe at the detected target, then makes relative motion between Fresnel zone plate and
the target to accomplish the encoding process, namely, to achieve the convolution between target reflection function and
the Fresnel zone plate intensity distribution function. The design scheme of the proposed system is presented. The
proposed technique offers significant practical benefit for ground-based imaging of objects in many important military
applications.
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