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81.
A new scheme of optical film sensor is presented. The sensor is based on p-polarized reflectance, consisting of a sensing coated substrate, is easily optimized for maximum sensitivity in different applications. The resolutions of refractive index nf, extinction coefficient kf and thickness hf of the sensitive films are predicted to be 10−7, 10−5 and 10−3 nm, respectively. Experimentally, we selected the sol–gel derived SnO2 films as gas-sensitive films and conducted preliminary gas-sensing test. The results indicate that novel optical film sensor scheme has higher sensitivity, and the detection sensitivity is available to 10−1 ppm on the condition of optimum optical parameters and incident angle. 相似文献
82.
Soraya A. Khodier 《Optics & Laser Technology》2004,36(1):355-67
A combined interference and diffraction pattern, in the form of equidistant interference fringes, resulting from illuminating a vertical metallic wire by a laser beam is analyzed to measure the diameter of four standard wires. The diameters range from 170 to 450 μm. It is found that the error in the diameter measurements increases for small metallic wires and for small distances between the wire and the screen due to scattering effects. The intensity of the incident laser beam was controlled by a pair of sheet polaroids to minimize the scattered radiation. The used technique is highly sensitive, but requires controlled environmental conditions and absence of vibration effects. The expanded uncertainty for k=2 is calculated and found to decrease from U(D)=±1.45 μm for the wire of nominal diameter 170 μm to ±0.57 μm for the diameter 450 μm. 相似文献
83.
84.
本文阐述了伺服系统结构设计中估算系统固有频率的必要性,介绍了一种分析和计算经纬仪方位伺服系统扭转振动固有频率的方法。 相似文献
85.
I.V. Kityk A. Ali Umar M. Oyama 《Physica E: Low-dimensional Systems and Nanostructures》2005,27(4):420-426
We have found that the gold nanoparticles on the ITO substrates might be considered promising materials for circularly polarized light-induced linear electrogyration (EG). The maximal achieved value of the EG susceptibility described by third-order axial tensor caused by probe circularly polarized light at a wavelength of 1060 nm was equal to about 13 deg/mm at pulsed electric field strength 30.0 V/cm with a duration of about 1 ms. We have revealed that the maximal EG coefficient is achieved for the samples possessing maximal resistivity. The investigated composites possess long-lived EG grating which decreases by not more than 12% after 120 min of laser treatment. Applying a non-circular pump light leads to the diminishing of the observed EG. 相似文献
86.
Amylopectin tris(phenylcarbamate) has been evaluated as a chiral stationary phase for HPLC; the influence on its cptical resolving capabilities of mobile phase composition and nature of the alcohol used as modifier has been studied. Separation and resolution of twelve arylalcohol racemates were examined. In most instances, the stationary phase exhibited high optical resolving capacity. 相似文献
87.
We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as
a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H2O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with
similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized
with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS
NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared
ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence
measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties. 相似文献
88.
We study the aggregation of oxygen dipoles well dispersed in a CaF2 crystal upon annealing at temperatures ranging from 370 to 420 K. The concentration of oxygen dipoles is monitored by measuring the intensity of the ionic thermocurrent peak as well as by absorption and luminescence spectroscopies. Results from three methods agree within experimental error and yield an activation energy of (1.2±0.1) eV for the diffusion of isolated oxygen centres in the crystal. 相似文献
89.
The analysis of a demodulation system for Fiber Bragg Grating sensors based on two fixed spectral filters has been carried out both theoretically and experimentally. Different system configurations were analyzed by modifying the spectral position of the filters as well as the optical power-level of the signal reaching the two photo-detectors. Measurements with integration times that varied from 0.01 to 1 s have been compared with the low-frequency limit predicted for long-term operation. Comparisons between simulated and experimental results show good agreement, and extrapolations indicate that it should be possible to achieve an operating spectrum range of the order of 7 nm, with uncertainties equivalent to less than 2 pm in measurements of the sensor peak position. 相似文献
90.
电子被HF和HCl分子散射总截面的计算 总被引:1,自引:1,他引:0
利用光学势方法计算了能量在10eV—1000eV范围内电子被H、F和Cl原子散射的总截面,并与已有的实验结果和理论计算进行了比较;又利用可加性规则(additivityrule)计算得到了电子被HF和HCl分子散射的总截面,计算结果也与已有的实验结果和理论计算进行了比较 相似文献