Key Engineering Materials Vol. 552

Abstract: Ultra-smooth optical surfaces are very important in widely fields. They’re not only used in optics, but also in the electronics. Ultra-smooth surfaces are difficult to process, because the rms is less than 1nm. The process methods have Teflon Polishing, Float Polishing (FP), Magnetorheological Finishing (MRF) and Ion Beam Figuring (IBF) etc. Compared with conventional polishing, IBF have higher processing quality and efficiency. Low-energy (<2Kev) IBF can form the self-organized nanopatterns on optical surfaces. Since IBF is a non-contact method; there is no edge effect during the process. We can change the ion beam parameters to get dot or ripple pattern on substrate. Only the self-organized ripple pattern is discussed in the paper. For the prediction of process parameters, the principle theories Sigmund theory and BH model are used the interplay between the angle of ion beam incidence, ion flux, incident energy and substrate temperature leads to the self-assembly, which are considered by these theory. In this paper the angle of incidence and incident energy are mainly researched on. Processing nanopatterns on Si has been simulated by SRIM program with these theory and the results reveal several laws in the process. It is believed that these laws will help us to well predict the ion beam parameters and lead IBE experiments.

Abstract: In this study, we investigated DLC-Si films were deposited by PECVD from C4H10:SiH4:O2 gas mixtures. We aim to investigate the influence of hydrogen on the variation of echanical properties and microstructure of DLC-Si films synthesized by radio frequency plasma chemical vapor deposition (r.f.-PECVD). The DLC films were deposited on a silicon substrate. That the reactant gases employed in this paper are a mixture of composition. The films deposited were studied by atomic force microscope (AFM), Raman and Fourier transform infrared (FT-IR) spectroscopy. The test results show that the ratio of SiH4 in the gas mixture was successively varied to clarify its influence on the roughness, microstructure, hardness, refractive index for the DLC films. The results reveal that the increasing of the concentration of SiH4 increases sp3 ratio, refractive index and roughness. Meanwhile, increasing the SiH4 concentration causes the decrease of hardness. Finally, optic behavior is correlated to the silicon concentration for deposition with SiH4 containing reactant gas.

Abstract: This paper introduced a kind of fast tool servo (FTS) that its stiffness is adjustable. Based on in the frame rack, flexible hinge, piezoelectric ceramic driver, tool base, diamond tools and so on, a spring assembly appendixes on. The spring assembly is consisting of spring rack, the sleeve, spring, and lock circle etc. Spring rack is fixed in front of the frame rack; there is a screw hole in the middle of the spring rack; there is also a screw outer side of the sleeve that mounted through the screw hole. The spring is installed inside sleeve; one end of the spring contacts with the bottom of the sleeve, and the other end contacts with the flexible hinge on frame rack. It can adjust the force of the spring that presses to the flexible hinge by rotating the sleeve. Through replaced the spring, it can makes stiffness of the FTS changed. It is verified that the device has the stiffness adjustable function through calculation and simulation.

Abstract: ArF excimer laser is the main light resource for the microlithography technology. In the laser cavity, the optical components with lowest absorption and scattering loss are necessary. As a consequence only a few materials are promising candidates for 193nm coatings with high transmittance or high reflectance. Fluoride films exhibit relatively low optical loss as well as high laser induced damage thresholds. The potentiality of LaF3 and MgF2 is evaluated in respect of the production of improved optical coatings for applications. For this purpose, single layer is prepared by thermal evaporation at the deposited temperatures of 523K on Fused Silica. A first order bulk inhomogeneity model for extracting the optical constants of weak absorbing film is applied, which is based on spectrophotometry. Refractive index (n) and extinction coefficient (k) of the optimal LaF3 film are 1.678 and 2.24×10-3 at 193nm. In the case of the optimal MgF2 film, n and k are 1.443 and 4.72×10-4 at 193nm. High reflection (HR) LaF3/MgF2 coatings are designed and fabricated for normal incident on CaF2. The experimental results indicate that after coated and fluoride coatings deposit, according to optimal process, can have more suitable optical properties at deep ultraviolet (DUV), the reflectance of HR coatings reaches more than 98% at 193nm.

Abstract: In recent years, for the compact system structure of aspheric lens, it has improved the image quality and excellent performance. More and more applications, in a variety of precision instruments, require the aspheric surface machining precision, fast, batch production. In order to further seek the effective method of aspheric surface processing, the aspheric NC machining technology is put forward. Therefore, this paper studies the aspheric surface in NC machining process of milling molding, polishing and polishing equipment related process parameters. Focusing on the milling process of various parameter settings, the resilient mold and small grinding head fixed combination method of polishing is introduced into the milling feedback compensation, solution of the elastic die polishing on the profile accuracy of destruction and processing to meet the requirements of the drawings of components: the contour measurement method on the profile accuracy of testing and surface shape accuracy of 0.5924um.

Abstract: This paper presents a method of laser interference nanolithography for the formation of interference patterns on the resist using a fiber semiconductor laser with a wavelength of 405nm. In the method, surface pattern structures are fabricated through the control of the incident angles of two interfering beams, the exposure dose of laser radiation and the development time. The angle adjustment becomes more convenient and the influence of environmental variations on the system has been reduced due to the use of fiber optic components. In the work, a feature size of down to 63nm and a pattern period of 215nm were achieved. The experimental results have shown that the method can be used for low cost micro and nano fabrication of periodical surface patterns with the features of low cost, simplicity and flexibility.

Abstract: In this paper a new three-dimensional large-size optical measurement system by laser radar has been proposed in combination of double-optic circuit measuring technology, ultra-high frequency modulation technology and laser intellectual tracing and location technology. The system can measure 3d shape unconnectedly for lager-size object, which has the advantages of high accuracy, automatic measurement and freedom from being influenced by material and light ray.

Abstract: According to the state of testing technology for laser designator multi-parametric, a multi-parameter integrated detection method on the basis of optical collimation and digital image processing technology is proposed, and the way for the detection of multi-parameter characteristics and integrated detection is analyzed. By using the detection principle of large aperture lens focus spot method, the parameter measurements, such as the divergence angle of the laser designator beam, displacement amount of the light spot move, spot of adjustment range and deviation and the multi-axis consistency are measured. Simultaneously, the parameters of the sight line alteration of daylight aiming sight, the graduation precision can also be tested. By the analysis of experiment,the method has high detection accuracy and detection efficiency.

Abstract: A way to achieve pyroelectric detector fast response compensation circuit based on the measurement of energy for high-repetition-rate pulse laser is proposed in this paper. The transfer function of the pyroelectric detector circuit system is derived adopting the linear model of the operational amplifier and the effect of input voltage and noise are ignored. Further, the noise characteristics and related factors are analyzed and their effects on the response speed, performance stability, signal gain and signal to noise ratio are discussed. Series of experiments were carried out to verify the reliability of the compensation circuit. This circuit has been applied in the pyroelectric detector system for measuring the energy and the power of high-repetition-rate pulse lasers. OCIS codes: 140.3538 040.1880

Abstract: Transmissivity and reflectivity of GaAs photocathode get from spectrophotometer are measured and analyzed according to various wave bands, so that the corresponding optics parameter is obtained. The typical optics parameter of various GaAs photocathode has been summarized. For blue-light extension photocathode, the diffraction peak will be close to ultraviolet wave band from the reflection curve. The thickness of Active layer film and optimal Si3N4 film on the GaAlAs layer have been acquired. The experimental and analyzed results have shown that the Si3N4 film on the GaAlAs layer should be about 1000A when the the GaAs photocathode got the optimum performance.The thickness of Active layer film should not be too thick to escape of electron and too thin to transfer of photon-electron. The experiment shows that the spectrophotometer can analyze epitaxial material and assist the manufacture of GaAs photocathode.