The thermal distortion of silicon reflector irradiated by high-power laser were analyzed by numerical simulation. The results indicate that the contributions from the thermo optic effect, photoelastic effect and deformation are about 97.4%, 0.65%, 1.95% for the transmitted beam. The ratio of thermal distortion between reflected beam and transmitted beam is 0.09.
The variable focus telescope is utilized now in the laser transmitter system design. It changes the telescope's
magnifying power in order to adjust the exit beam through moving the inner focus lens. This system has complicated structure and high machining expense. This paper investigates the focusing character of Gaussian beam through misadjust telescope and presents a new method for lidar transmission system design. The laser beam
divergence angle and the radius of exit beam are changed through moving the distance between the back focus of object lens and the front focus of ocular. This design can provide a convenient method for calculating the focusing parameters. The restriction of assembly dimension and the effect of fitting and adjusting error which should be considered in engineering application are studied, and then bring a method to choose the right parameters of focusing optic system by the focusing requirement.
Vignetting effect is a kind of typical nonlinear effect in the thermal imaging system and it will induce the
central region of the infrared image is bright, while the edge region is dark. This geometric phenomenon generates
because the radiation illumination which reaches the detector's surface decreases gradually with the increase of
off-axis distance. Vignetting makes infrared imaging system receive uneven effective energy of incident light-ray
from different angle, and the output signal is uneven sequentially. At last the final infrared image brings undue
light or dark distortion and the generated infrared image is inconsistent with the real scene. Infrared imaging
system works under low contrast between 1 percent and 2 percent. Therefore, the vignetting effect of thermal
imaging system influences the quality of infrared imaging seriously. So the exact modeling of vignetting effect is
vital for generating an infrared simulation image through optical system. This paper builds a realistic model for the
vignetting effect resulted from infrared optical system and analyses the cause of the vignetting effect
theoretically. Then simulation is carried out and the simulated results show that the simulation method of vignetting
effect can provide the more precise and real infrared image signal to evaluate the capability of infrared imaging
system and advance the whole performance.
The enhancement, segment and edge detection of infrared images are one of the key techniques in precise guidance. It
owns strong application background and is studied widely. The soft mathematical morphology can compress the noise
effectively, get better processing results and complete processing in real time. In addition, the structuring systems are
constructed in advance and remain unchanged in general image processing. This property can make the method run in
parallel effectively. So it is well adapted to infrared images processing. In this paper, we analyzed and discussed the
applications of soft morphology theory in infrared ship image. We introduced the soft mathematical morphological
operations in section two. Then the hardware framework of DSPs was given briefly. The software design and code
optimal design were also discussed. At last the conclusions are drawn.
The laser radar is a radar system adopting laser photosource and operating on optical band and the laser
heterodyne measurement is a detection technique with high sensitivity. Optical system plays an important role in
heterodyne detection system. The reasonable selection of performance parameters of optical system has direct
influence upon the ability of system to detect objects. The characteristics of the receiver and the transmitter are
discussed in this paper. In order to make the diffraction disk matching the detector size, the laser beam are confined
and made the beam divergence angle of the transmitter equal to the receiver angle determined by antenna theory. In
order to transmit laser to target's surface and receive the echo from the target efficiently, each optical parameter of
the detective system must accord with the coherent condition. The CO2 laser coherent imaging radar system
established by us can get the photo-quality imaging of the target and it has wide application foreground. Primary
parameters including beam expander's clear aperture, beam divergence angle, the focus of system etc and
calculating examples were given to show how to determine the parameter of optical system and realize these
purposes.
In all of precise guidance technology, imaging laser radar guidance technology is one of the most important orientations
in the future development of precision guidance. The laser radar is a radar system adopting laser photosource and
operating on optical band and the laser heterodyne measurement is a detection technique with high sensitivity. It can
advance the hitting precision, the ability of resisting disturbing and breaching defence greatly. The numerical simulation
technology can simulate some results of outfield experiments to a certain extent and becomes a new method for imaging
laser radar guidance system design. This paper simulates the imaging laser radar which adopts CO2 laser as photosource
and heterodyne detection. Our laboratory established the CO2 laser coherent imaging radar system. It consists of CO2
laser, acousto-optic modulators, beam-expending telescope, magnifying circuits and control computer etc. Firstly, the
ranging equation of laser radar is analyzed. Then five models for the simulations of laser imaging radar are established
including atmospheric transmission model, laser transmitter and laser receiver model, noise model, targets model, image
processing and target recognizing model. The stimulation system of CO2 laser initiative imaging radar can operate easily
and foresee the questions of the practicality design. The system had finished the elementary simulation and could
evaluate accurately the capability of laser radar through the system's numerical simulation. It can estimate the key
characteristic parameters and help to project design and capability advancing for experimental system.
To solve the problem of slow speed in single point scanning confocal measurement, a new way to make 3-D morphology
confocal detection by optical fiber beam is presented. In the new system, with the point light source produced by optical
fiber array and light intensity information detected by pinhole array, the synchronous scanning of the measured surface is
done. Compared to the multi-probe detection system of lens array, the new system has the characteristics of simple
structure and low price. Based on the general confocal principle and with Fourier optics theory, the 3-D point spread
function of a simple fiber pinhole pair is got. With the matrix operating form, the imaging characteristic of the
multi-probe measurement system is analyzed. Meanwhile, the conclusion of theoretical analysis shows the total light
distribution of the multi-probe detection system conforms to the multiplication form of each detection light path.
The IR smoke is a typical sort of aerosol. The radiation is covered by the smoke aerosol, which lead attenuate further more. This covering effect is obtained from the absorption and dispersion of the aerosol. The degree of the attenuation of the aerosol is determined by two important parts: the size and the component of the aerosol particulate system. According to the equation of the signal-noise-ratio of the IR system, the covering effect can be reflected by the spectral permeation rate. The attenuation of the aersol is composed of the absorption and the dispersion when the size of the smoke particular is as that of the radiation wavelength. The key issues to calculate the radiation are three factors: the radius, the density and the refraction rate of the smoke material. Another important part which influences the attenuation is the relative humidity of the atmosphere. A lot of factors, such as the Brown motion, the temperature diffuseness, the consistency diffuseness and the climate affect the formation and the distribution of the smoke aerosol.
A novel experimental technique to measure the energy- dependent unimolecular dissociation rate k(E) of radical species is presented. Internally excited CH3CO radicals were formed by ultraviolet photodissociation of CH3COCl, and the subsequent decay of these radicals was detected by subpicosecond time-clocked photofragment imaging. The CH3CO radicals with different internal energies were dispersed in space by their recoil velocities, and their decay rates were measured for each internal energy.
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