The laser one-dimensional range profile of a target can be approximated as the convolution of the transmitted laser pulse and the range-resolved laser radar cross section. Therefore, the widening effect caused by the laser pulse is eliminated as much as possible by echo deconvolution, and the resolution of the target laser one-dimensional range profile detection can be improved to some extent. To this end, the Richardson-lucy image iterative deconvolution algorithm is introduced into the laser echo deconvolution. Although the algorithm can eliminate the influence of Poisson noise effectively，In order to further improve the deconvolution effect, wavelet noise reduction is first performed to improve the signal-to-noise ratio of the measured data before using the algorithm. The effectiveness of the proposed algorithm is verified by simulation experiments.
By using the geometrical optics and physical optics method, the models of wedge plate interference optical path, Michelson interferometer and Mach Zehnder interferometer thus three different active interference pattern are built. The optical path difference (OPD) launched by different interference patterns, fringe spacing and contrast expression have been derived. The results show that far field interference peak intensity of the wedge plate interference is small, so the detection distance is limited, Michelson interferometer with low contrast affects the performance of detection system, Mach Zehnder interferometer has greater advantages in peak intensity, the variable range of interference fringe spacing and contrast ratio. The results of this study are useful for the theoretical research and practical application of laser active interference detection.
In this paper, laser radar range profile theory and simulation method are investigated. Laser radar range profile theoretical formula is given based on the theory of Gaussian laser beam, BRDF, and target shape. On the purpose of simulating the range profile of certain targets, the geometrical 3D models of some simple and complex objects are constructed respectively, and then the viewpoint coordinate and target coordinate are established. The location information of vertexes and facets can be obtained and exported to utilize. In next step their laser radar range profiles in many postures are acquired and compared sequentially. The influences of Gaussian pulse width, target shape, size and transmit-receive angles on the simulation results are discussed. In this way this paper can provide theoretical and simulation methods and bases for extracting target features and recognizing targets using laser radar range profiles.
The optical aperture of cat-eye target has the aperture averaging effect to the active detecting laser of active laser detection system, which can be used to identify optical targets. The echo scintillation characteristics of the transmission-type lens target have been studied in previous work. Discussing the differences of the echo scintillation characteristics between the transmission-type lens target and Cassegrain lens target can be helpful to targets classified. In this paper, the echo scintillation characteristics of Cat-eye target’s caliber with Cassegrain lens has been discussed . By using the flashing theory of spherical wave in the weak atmospheric turbulence, the annular aperture filter function and the Kolmogorov power spectrum, the analytic expression of the scintillation index of the cat-eye target echo of the horizontal path two-way transmission was given when the light is normal incidence. Then the impact of turbulence inner and outer scale to the echo scintillation index and the analytic expression of the echo scintillation index at the receiving aperture were presented using the modified Hill spectrum and the modified Von Karman spectrum. Echo scintillation index shows the tendency of decreasing with the target aperture increases and different ratios of the inner and outer aperture diameter show the different echo scintillation index curves. This conclusion has a certain significance for target recognition in the active laser detection system that can largely determine the target type by largely determining the scope of the cat-eye target which depending on echo scintillation index.
The analytical expression of beam-width of distorted cat-eye reflected beam under far-field condition is deduced using the approximate three-dimensional analytical formula for oblique detection laser beam passing through cat-eye optical lens with center shelter, and using the definition of second order moment, Gamma function and integral functions. The laws the variation of divergence angle and astigmatism degree of the reflected light with incident angle, focal shift, aperture size, and center shelter ratio are established by numerical calculation, and physical analysis. The study revealed that the cat-eye reflected beam is like a beam transmitted and collimated by the target optical lens, and has the same characteristics as that of Gaussian beam. A proper choice of positive focal shift would result in a divergence angle smaller than that of no focal shift. The astigmatism is mainly caused by incidence angle.
Cat-eye effect has been widely used in active laser detection, optical target identification and free space optical (FSO)
communication, but atmospheric turbulence makes laser beam fluctuate, which limits the use of cat-eye effect. The
optical aperture has the aperture averaging effect to the detecting laser, which can be used to identify optical targets.
Using the flashing theory of spherical wave in the weak atmospheric turbulence, the circular aperture filter function and
the Kolmogorov power spectrum, the analytic expression of the echo scintillation index of the cat-eye target of the
horizontal path two-way transmission was given in which the cat-eye target were equivalent to a combination of two
circular apertures and the detector of cat-eye target was equivalent to a reflecting plane with the reflectivity η when the
light is normal incidence. Then the impact of turbulence inner and outer scales to the echo scintillation index and the
analytic expression of the echo scintillation index at the receiving aperture were presented using the modified Hill
spectrum and the modified Von Karman spectrum. The simulation results show that scintillation index of considering the
inner scale is larger compared with that of without considering the inner and outer scales and considering the inner and
outer scales. Echo scintillation index shows the tendency of decreasing with the target aperture increases. The echo
scintillation index increases with the transmission distance increasing.
Based on the cat-eye effect of optical system, free space optical communication based on cat-eye modulating
retro-reflector can build communication link rapidly. Compared to classical free space optical communication system,
system based on cat-eye modulating retro-reflector has great advantages such as building communication link more
rapidly, a passive terminal is smaller, lighter and lower power consuming. The incident angle is an important factor of
cat-eye effect, so it will affect the retro-reflecting communication link. In this paper, the principle and work flow of free
space optical communication based on cat-eye modulating retro-reflector were introduced. Then, using the theory of
geometric optics, the equivalent model of modulating retro-reflector with incidence angle was presented. The analytical
solution of active area and retro-reflected light intensity of cat-eye modulating retro-reflector were given. Noise of PIN
photodetector was analyzed, based on which, bit error rate of free space optical communication based on cat-eye
modulating retro-reflector was presented. Finally, simulations were done to study the effect of incidence angle to the
communication. The simulation results show that the incidence angle has little effect on active area and retro-reflected
light intensity when the incidence beam is in the active field angle of cat-eye modulating retro-reflector. With certain
system and condition, the communication link can rapidly be built when the incidence light beam is in the field angle,
and the bit error rate increases greatly with link range. When link range is smaller than 35Km, the bit error rate is less
A fusion algorithm of hyperspectral and high-resolution images based on principal component analysis (PCA) and second generation Bandelet transform is proposed. Primarily, the numerous components of the hyperspectral image are divided. Subsequently, the maximum rule is used to select the Bandelet coefficients and geometry flows of the hyperspectral image which are transformed by PCA in the following step. Finally, the fused image is reconstructed by taking inverse PCA and Bandelet transform. Some numerical simulations are made to test the validity and capability of the proposed fusion algorithm.