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Kinetics investigations for holographic Bragg gratingbased on polymer dispersed liquid crystal 下载免费PDF全文
This paper investigates the monomer kinetics of polymer dispersed
liquid crystal (PDLC) grating. Fourier transform infrared (FTIR)
spectra are used in the studies of photoreaction kinetics. The
results indicate that there is a relative stable stage arises after
a very short initial stage. Based on FTIR studies, the monomer
diffusion equation is deduced and necessary numerical simulations
are carried out to analyse the monomer conversion which is an
important point to improve phase separation structure of PDLC
grating. Some simulation results have a good agreement with
experimental data. In addition, the effects induced by monomer
diffusion constant $D$ and diffusion--polymerization-ratio rate $R$
are discussed. Results show that monomer conversion can be improved
by increasing value of $D$. Besides, a good equilibrium state
($R=1$) is more beneficial to the diffusion of monomer which is
important in the process of phase separation. 相似文献
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The liquid crystal spatial light modulator (LC SLM) is very suitable
for wavefront correction and optical testing and can produce a
wavefront with large phase change and high accuracy. The LC SLM is
composed of thousands of pixels and the pixel size and shape have
effects on the diffractive characteristics of the LC SLM. This paper
investigates the pixel effect on the phase of the wavefront with the
scalar diffractive theory. The results show that the maximum optical
path difference modulation is 41\,$\mu$m to produce the paraboloid
wavefront with the peak to valley accuracy better than $\la$/10.
Effects of the mismatch between the pixel and the period, and black
matrix on the diffraction efficiency of the LC SLM are also analysed
with the Fresnel phase lens model. The ability of the LC SLM is
discussed for optical testing and wavefront correction based on the
calculated results. It shows that the LC SLM can be used as a
wavefront corrector and a compensator. 相似文献
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液晶波前校正器特性研究 总被引:1,自引:0,他引:1
利用808 nm大功率连续激光器研究了液晶的光功率承受特性结果表明,当功率密度为133 W/cm2时,液晶还能保持原有的光学调制特性,而且可以长时间稳定工作测定了液晶的波长色散特性,发现,随着波长的增加Δn值逐渐减少,近紫外300~400 nm波段Δn变化47%,而在400~780 nm变化量为28%,在780~900 nm Δn变化了2%还研究了温度对液晶波前校正器衍射效率的影响,随着温度的升高Δn逐渐减小,当温度从10℃升到90℃时,对于16台阶菲涅耳透镜,衍射效率下降了70%;但当温度在20℃变化10℃时,对4台阶菲涅耳透镜衍射效率最大变化量为1.7%,而对16台阶菲涅耳透镜,衍射效率降低了1.2%. 相似文献