Laser transmission is influenced by environment particularly large, especially in fog, rain, snow and other complex weather conditions.This article mainly from two aspects of theory research and Modtran software simulation discussed the laser transmission characteristics in the rain.Different laser is theoretically discussed mainly in a variety of transmission attenuation degree of rainfall conditions.Using Modtran simulation software to get the theoretical calculation results of simulation and error analysis.
Three dimensional autocollimator is based on a precise angular measurement method which has been proposed in our previous papers. Optimal design for the three dimensional autocollimator is one of the most important problem for the application of this method. Considering that the parameters and the properties of the optical system interact with each other, we analysis the relationships between the parameters and the properties in detail. It is indicated that there are four restrictions which should be considered during the design for the optical system. Then, an optimal design for the parameters of the optical system is proposed, and all the parameters of the optical system can be determined according to the properties of the autocollimator.
Proc. SPIE. 9142, Selected Papers from Conferences of the Photoelectronic Technology Committee of the Chinese Society of Astronautics: Optical Imaging, Remote Sensing, and Laser-Matter Interaction 2013
The scattering characteristics of a Gaussian laser beam and plane beam through spherical particle were studied. The incident field and scattering field of the Gaussian beam are expressed in spherical harmonic function, it’s expansion coefficient expression is given. Using of Matlab programming calculation, we simulate the spherical particle scattering intensity for two light beams, The results of the simulation are discussed, and the comparative analysis to plane wave scattering law were made. Results show that the scattering intensity distribution of Gaussian beam is different from the plane wave scattering law,. But under the condition of big waist radius, the scattering laws have a lot in common with the plane wave.
This article established the models of detection that groups of scattering particles flux with no relationship. According
to the MIE scattering theory under the generalized, we derived the scattering light intensity of a single aerosol particle scattering
of Gaussian beam and the luminous flux of ahead scattering formula. On the basic of the single particle scattering, we developed
the scattering luminous flux formula of the groups of scattering particles flux, obtained the total population prior to the scattering
luminous flux.Carried out using MATLAB editor and numerical calculation. The single particle flux and mass scattering curve
with the off-axis distance was be simulated. As the results shows that the different scattering angle, the detector receives the flux
is different; in the same axial distance, the luminous flux decreased quickly as the distance to the axiom increased. At the same
time, the luminous flux affected the waist radius largely. Waist radius of the smaller, the smaller flux. It affected the luminous
flux receiving when the groups of particles in different positions.
Compatible stealth of laser and infrared is an urgent demand of modern battlefield, but the demand is ambivalent for
conventional materials. As a new type of artificial structure function material, photonic crystals can realize broadband
thermal infrared stealth based on its high-reflection photon forbidden band. By forming a "hole-digging" reflection
spectrum of doped photonic crystals, high transmittance at military laser wavelength of 1.06μm and 10.6μm can be
achieved, so compatible stealth of laser and infrared can be achieved too. In this paper, we selected middle and far
infrared-transparent materials, PbTe and Na<sub>3</sub>AlF<sub>6</sub> as high refractive index and low refractive index material respectively,
and designed a one-dimensional two-defect-mode photonic crystal based on principles of distributed Bragg reflector
microcavity. And then its photon forbidden band was broaden to 1~20μm by constructing two heterojunction photonic
crystals. The reflection spectrum and transmission spectrum of the photonic crystals were calculated by characteristic
matrix method of thin-film optical theory. The calculation results show that the designed multi-cycle dual-heterojunction
photonic crystal has a high spectral reflectance in the near, middle and far infrared band, whose spectral reflectivity is
greater than 99% in 1~5μm and 8~14μm infrared bands, and spectral transmittance at 1.06μm and 10.6μm is greater than
96%. This will satisfy the laser and infrared compatible stealth in the near, middle and far infrared bands.
The escaped and trapped emission of organic light-emitting diodes was investigated by an integrating sphere and a
fiber spectrometer. It was found that the ratio of escaped emission to the escaped and trapped in the substrate emission is
71%. In order to explain our experimental results, we extended the half-space dipole model, in which the dipole radiation
pattern is taken into account. The calculated escaped and trapped emission of devices agreed well with our experiments.
Our experimental and theoretical results is expected to be an instruction to the optimization of device structures for
improving the out-coupling efficiency.
Optical microcavity is a high quality factor micro-cavity with a size of the resonant wavelength. By using of
spontaneous emission modulation of organic gain medium, an organic microcavity laser can be achieved. In this paper, a
metal Ag-dielectric DBR mirrors mixed organic micro-cavity structure was proposed in this paper. And the influences of
center wavelength, growth sequence and the cycle number of DBR, and the thickness of Ag mirror and organic
light-emitting layer on performance of Ag-DBR mixed organic micro-cavity were investigated by simulation. And then
according to PL characteristics of Alq3:DCM(0.5wt%), an optimal metal Ag-DBR microcavity structure was designed,
and based on theoretical calculation results, a corresponding microcavity devices (air/Ag/organic layer/DBR/glass) was
fabricated. The experimental and theoretical simulation results are in good agreement. The results show that the
calculation method of ours is of great guided significance on the fabrication of metal-DBR organic microcavity lasers.
We have studied a cascade energy transfer based on the long-range dipole-dipole Forster energy transfer between
polymer and two fluorescent dyes in surface emitting microcavities, which is formed by sandwiching a
poly(N-vinylcarzole) (PVK) film doped with 8-trishydroxyquinoline (Alq3) and 4-(dicyanomethylene)-2-tert-butyl-6 (1,
1, 7, 7-tet ramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) between a distributed Bragg reflector (DBR)(with a reflectivity
of 99%) and a silver film (which depth is 140nm). The sample was optically pumped by a frequency-tripled Nd:YAG
laser (Continuum Surelite I) delivering 5.55ns pulses at 355nm with a 10Hz repetition rate. By optimizing the
concentrations of Alq3 and DCJTB in PVK, a low lasing threshold of about 9.62ΜJ per pulse attributed to efficient
cascade Forster energy transfer form PVK and Alq3 to DCJTB was obtained. The full width at half maximum (FWHM)
of the emission was 3nm with the peak wavelength at 630nm. Our results demonstrate that the PVK:Alq3:DCJTB could
be a promising candidate as gain medium for red organic diode lasers.
A novel polymer distributed feedback (DFB) gratings are developed via UV photopolymerization in order to lower lasing threshold to realize electrically driven polymer lasers. A photopolymer formulation sensitive to 355 nm ultraviolet light is proposed for the fabrication of polymer gratings can be used to form polymer films by spin-coating process. Polymer gratings with periods ranging from 200 to 1000 nm were fabricated based on photopolymerization-induced internal diffusion process. A very low surface relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive index modulation Δn of about 0.012. Results of theoretical analysis indicate that the quality of the polymer film should be improved in order to improve the refractive index modulation of short-period DFB gratings. Such polymer gratings show promising potentials for the fabrication of low-order DFB organic semiconductor lasers.
We studied a new optics-ammunition mechanism by an adiabatic heating model of exploding wires on strong pulsed
current and a model of shock waves inspired by exploding wires blasting in inert gases. A Pspice simulation code for
engineering applications and an improved MHD (Magnetohydrodynamics) computation code for physics research have
developed in this paper. The computation results indicate that, firstly, plasma radiation intensity increased by Machnumber
of shock waves, and in all insert gases, argon's Mach-number of shock waves is highest. Secondly, silver is the
best in common metal materials, and the exploding time and current peak is about linear with the number of wires.
Thirdly, the parameters of wire including the diameter, length and number will influence the exploding performance
deeply; Fourthly, Pspice computation is an experiential method, but the result has direct guiding sense for engineering
design. Fifthly, the improved 1D single temperature MHD model can be used in multi-wire paralleled electricity
exploding computation very well, and computation results agree with the known experiment data and are important to
the study of strong pulsed IR optics-ammunition.
In this paper, a convolute structure optoelectronic hybrid processing system for cruise missile scene matching guidance based on Joint Transform Correlator was proposed. An electrically addressed liquid crystal displays (EALCD) controlled by computer was used as spatial light modulator (SLM) was placed on input plane, on which reference image and target image were juxtaposed to display; in addition, CCD camera as a square law detector was placed in frequently spectrum plane recorded joint transform power spectrum and correlation result. Owing to detected the joint power spectrum and correlation result by CCD camera, the system could achieve sharper correlation peak and location accuracy by using edge detection input image and binaryzation of joint power spectrum. It was very advantageous to meet the demand of further improving performance, speed, strike accuracy of the cruise missile. Computer simulation and optical experiments showed that even in noisy background, the system can achieve excellent recognition and location performances with max speed: 16frames/s, recognition probability greater than 94%, and location accuracy better than a pixel.
In this paper the four-channel real-time joint transform correlator (JTC) for fingerprint verification is proposed which is consists of right-angle prism, 4f system, liquid crystal light valve, hololens array and CCD. Fingerprint image is inputted real-timely using a right-angle prism and processed by 4f system optically to insure the higher contrast. To avoid refusal phenomenon owing to fingerprint images distortion, the single channel correlation identification is changed to four-channel correlation recognition using hololens array. A little different reference fingerprint images from an identical finger are placed in different channels. When a object fingerprint image is inputted, four kinds of correlation results are presented. Not only the recognition accuracy is increased but the processing speed and capability of the system is enhanced. The experimental results are given in this paper.