Silicon thin films were prepared on silica substrates by ion beam sputtering, electron beam evaporation and ion assisted deposition. The transmittance spectrum, the reflectance spectrum and the ellipsometric spectrum were obtained in the wavelength region from 300nm and 2000nm, where Lambda 900 spectroscopy and VASE ellipsometer were applied. The optical constants were calculated by multiple spectrum analysis with WVASE32 which is the analysis software for ellipsometry of J.A.Woollam company. There were about ten nanometers of silicon dioxide layers on the surface of the silicon films. The near infrared extinction coefficient of the silicon thin film prepared by ion beam sputtering was the largest, followed by ion assisted deposition, the extinction coefficient of the electron beam evaporated silicon film was the smallest, and the refractive index of the electron beam evaporated silicon thin film was the lowest. The heat treatment experiments of 300°C and 400°C showed that the refractive index of the 600nm-200nm band of the ion beam sputtering silicon film decreased obviously, while the refractive index of the electron beam evaporation and the ion assisted deposition silicon thin film had little change, and the heat treatment at 300°C could significantly reduce the extinction coefficient of the near infrared band of the three silicon thin films. In the further heat treatment at 400°C, the extinction coefficient of the ion beam sputtering silicon film and the ion assisted deposition silicon film continued to decrease, while the extinction coefficient of the electron beam evaporated silicon film increased.
The radiation wavelength of the carbon dioxide is 4.3μm. It is a kind of background noise that affect the image contrast in infrared imaging system seriously. Mirror is an important optical element in infrared optical system. This paper intends to design a 4.3μm wavelength filter base on the mirror. So, it is called reflective filter. It can replace the original mirror in the infrared optical system in order to filter out the radiation wavelength of the carbon dioxide and enhance the image quality. The reflective filter consists of metal and dielectric films. The absorption of the Al film which is the underlayer has been induced by the outer side dielectric multilayer films at 4.3μm. And it will keep high reflectivity in other wavelength at the same time. The design result as follow was obtained after optimization design. The average reflectivity is about 98% in the range of 3.7-4.2μm and 4.4-4.8μm (reflection bands) and the reflectivity is less than 10% at 4.3μm (absorption band) when the incident angle is 45°. The reflection phase of the metal-dielectric films was analyzed. The electric field distribution of reflection bands and absorption band was shown respectively. At last, in order to filter out the peak as much as possible, the design method and result of absorption band widening of the reflective filter was shown. Compare the all dielectric transmission minus filter, the layer number of the reflective filter is fewer and the total thickness of the coating is lower. Therefore, the manufacturing process became easier. The reliability became higher. More important, a better parameter of filter was obtained.
ZnSe is widely used in infrared optical systems because of the good optical characteristics in 0.5~22μm and the good processability. Physical Vapor Deposition(PVD) of ZnSe is good at no pollution in production process, lower price, etc. Infrared optical parts should be made by single point diamond turning or single point diamond fly-cutting after the experimental investigation of the ultra-precision turning capability of PVD ZnSe. The orthogonal experiment of ultra-precision turning PVD ZnSe was done at first, then the smooth turning surface and the rough turning surface were observed by metallographic microscope and 3D profilometer, and the mechanism of the defects on the turning surface was discussed. The result shows: the quality of ultra-precision turning surface of PVD ZnSe was restricted by the grain size and the distribution of the grain which could easily cause the variegated macula at the grain size, rising the spindle speed, reducing the feed rate and reducing the cut depth could make the quality of ultra-precision turning surface better and reduce the roughness Ra value lower, the roughness Ra value of the smooth turning surface was reached 3~4nm which is enough to the infrared optical image systems currently by using the optimization of parameters.
Microscopic morphology and XRD spectra of Hot Press(HP) ZnS powders and fractrues were tested. Preliminary analysis of the turning characters of HP ZnS was got by associating with the characters of HP ZnS and the processing mechanism of hard and brittle materials. Orthogonal experiment of 3 factors and 3 levers was taken by setting roughness Ra value index of the turning surface, and more analyses of the ultra-precision turning characters of HP ZnS were got by associating with the 3D microscopic morphology of CVD ZnSe ultra-precision turning surface and HP ZnS polishing surface. How to get the lower Ra value was discussed at last. The research shows: the primary removal mechanism of HP ZnS is powder removal; HP ZnS can get good ultra-precision turning surface which Ra value is lower than 10nm; to get the Ra value of the turning surface lower than 4nm, speed of main spindle, blunt edge radius, and the corner radius must be optimized because of the polycrystalline structure of the HP ZnS.
7.5 ~ 9.7μm traditional wide band antireflective (AR) film is designed on ZnS, choosing Ge, ZnS and YF<sub>3</sub> as film material, and the average transmittance (<i>T</i>) could be elevated from 74.9% to 98% when AOI=0°. But while AOI=70°, <i>T</i> of <i>p</i> and <i>s</i> component is 85.9% and 75.6% separately, and the average transmittance is 80.8% because of the separation of <i>s-</i> and <i>p-</i>polarized light. Depolarization antireflective film is also designed with the same materials by equivalent-layer method to balance <i>s-</i> and <i>p-</i> component energy, and the polarization effect at different incident angles is analyzed. When AOI=0°, <i>T</i> is 99.3%, and when AOI=70°, <i>T</i> is 90.6%, 10% less than that of traditional AR film. So equivalent-layer method is effective to eliminate polarization effect of broadband antireflective coatings at large incident angle and then could effectively improve the optical performance, which is critical in precision guide system.
A high temperature infrared spectra measuring equipment connected with a FTIR spectrometer (PE) was designed and manufactured. The measuring temperature can range from room-temperature to 500°C and the infrared spectra of substrates and thin films under different temperature can be real-time measured. The Fourier transform infrared transmission spectra of Si substrate under different working temperature were measured in the wavelength region from 2μm to 20μm using high temperature infrared spectra measuring equipment. The measured temperature ranged from room temperature to 500°C with a step of 50°C. Complex dielectric functions of Si substrate under different temperature condition are calculated from FTIR transmittance spectra by WVASE32 software, and the best fitted method was obtained for calculating optical constants of dielectric materials in the high temperature condition. As the increase of working temperature, the refractive index and extinction coefficient of Si substrate increase, when the working temperature reach 300°C, the various quantity of extinction coefficient sharply increase, so Si substrate can be used in the condition below the temperature of 300°C. Thus, through the exact calculated complex dielectric functions under different working temperature condition, we can design and manufacture different thin films using Si as substrate, and applied in in the high temperature condition.
Annealing is an important method to alter the properties of thin films. The effects of thermal treatment in air on optical
properties of SiO<sub>2</sub> thin films were investigated. SiO<sub>2</sub> thin films were deposited on Si (110) substrates by an ion beam
sputtering (IBS) technique, and then annealed in air under different thermal annealing time of 16 hours, 24 hours, 36
hours, 64 hours and the temperature from 100℃ to 600℃ with 24 hours. Optical properties refractive index and
thickness are studied directly after deposition and after thermal treatment, and they are measured by spectroscopic
ellipsometry. When the thermal annealing temperature was fixed at 300℃, the refractive index of SiO<sub>2</sub> films would
reduce with the increase of the thermal annealing time, the optical thickness also reduced but the various quantities are
almost the same. The refractive index of SiO<sub>2</sub> films changed with the different thermal annealing temperature. As the
annealing temperature increased, the refractive index of SiO<sub>2</sub> films reduced gradually. When the selected annealing
temperature is 500℃, the refractive index of SiO<sub>2</sub> films reached minimum. It can be found that the optical properties of
SiO<sub>2</sub> thin films can be improved by an adapted annealing procedure.
SiO<sub>2</sub> is a very important low refractive index material and usually used in combination with high refractive index
material to manufacture the coatings with low optical loss. In this paper, SiO<sub>2</sub> films were deposited on Si substrates by an
ion beam sputtering (IBS) technique and SiO2 target with purity of 99.99% was used as SiO<sub>2</sub> thin films forming material.
The thickness of SiO<sub>2</sub> films grown onto Si substrates are about 900 nm. Aging optical properties of SiO<sub>2</sub> films were
investigated as a function of time placed in the air. Spectroscopic ellipsometry was used to measure optical constants of
SiO<sub>2</sub> films. The refractive index of SiO<sub>2</sub> films change with the increase of placed time. When the placed time reaches
more than 200 days, the value of refractive index tends to be constant and the corresponding variation rate is about 0.5%.
As the placed time increases, the physical thickness and optical thickness also drive to be stabilization. It can be seen that
optical properties of SiO<sub>2</sub> films prepared by IBS technique under some process parameters are very stability.
Proc. SPIE. 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology
In order to take full use of SAR image dark areas information, texture recognition method of SAR image based on
Surfacelet transform is proposed. Firstly, SAR image in test samples is decomposed into brightness SAR image and
reflection SAR image based on Retinex model; secondly, the decomposed SAR image carries through Surfacelet
transform, in order to reduce computational complexity and shorten the follow-up recognition time, the decomposed
SAR image is processed two dimension three level scale Surfacelet transform, and the first level is 8 directions, the
others are 8,2 directions respectively, after image Surfacelet transform, the sparsity of the distribution coefficient is even
more evident, especially high-frequency sub-band; thirdly, coefficient matrixes of high-frequency sub-band reduce
dimension processing by using the singular value decomposition theory of matrix; fourthly, the final eigenvector are
composed of character of energy of coefficient matrix in low-frequency sub-band and first and second-order moment of
coefficient matrix in intermediate frequency sub-band and eigenvector by reducing dimension in high-frequency subband;
at last, use BP neural network to train with supervised and recognize of samples. The method takes full use of SAR
image dark areas information, and the simulation results show that the method the recognition rate is better than other