A simpler and lower cost Reactive Ion Figuring (RIF) process was demonstrated, combining with flexible film photomasks and an algorithm of masking layers distribution for less iteration. As a novel alternative figuring technology, RIF with parallel removal mode and chemical removal mechanism has showed the actual potential for large segment class figuring, especially in mass production of lightweight optical membrane components. Although diffractive membrane optics has been expected to meet the requirement of large aperture space-based telescopes, the flexible membrane has so different properties from traditional materials that the desired geometrical form is hardly obtained by current ultra-precision surface manufacturing technologies. In this paper, a 300 mm aperture polyimide membrane substrate was figure-corrected by RIF from the initial figure error of 62 nm rms to the final figure error of ~20 nm rms in total effective figuring time of ~4.3 minutes. Film photomask lowered the cost of photomask fabrication down to less than two hundredths of that of quartz photomask fabrication. All distributions of protected regions and removed regions, i.e., the patterns to be fabricated onto film photomasks, were obtained from the transmitted wave-front map just at the start of the entire RIF process. After 2 iterations, it took ~4.3 min to figure this sample and the 20 nm RMS is obtained with a RMS convergence ratio of 3.1.
Gas flow distribution of reaction chamber of reactive ion etching (RIE) etcher is usually considered to be a main factor in determining both the plasma distribution and etching uniformity. Based on the continuum fluid and heat transfer models of the commercial software, Fluent(Ansys), the gas flow distribution of the reaction chamber was simulated. And then the spatial distribution profiles of the pressures above the electrode surface under the different mass flow (50～250sccm) inlet conditions , and the influence of the different GAP (L = 0.03～0.06m) of the chambers on the gas flow uniformity were discussed. The result shows that the pressure distribution above the electrode has the character which the pressure is higher in the center of the electrode and lower at the edge and increases with the rise of the mass flow of inlet. And the uniformity of the gas flow distribution is enhanced with the rise of the GAP of the chamber.
This paper presents an approach used to fabricate resonant subwavelength grating based on thiol-ene material. First of all, polydimethylsiloxane soft imprint stamp with opposite structure of the subwavelength grating master mold is made by casting. Then, the desired subwavelength grating with UV-curable thiol-ene material grating structure is fabricated using the polydimethylsioxane soft stamp by UV-curable soft-lithography. Here, we fabricate a subwavelength grating with period of 300nm using the approach, which could reflect blue light with wavelength ranging from 448nm to 482nm at a specific angle and presents the excellent resonant characteristic. The experimental results are consistent with the simulation results, demonstrating that the approach proposed in this paper could effectively fabricate the thiol-ene material resonant subwavelength grating structure. The thiol-ene material is a new green UV-curable polymer material, including a number of advantages such as rapid UV-curing in the natural environment, low-cost, high resolution, and regulative performance characteristic. The fabrication technique in this paper is simple, low-cost, and easy to high throughput, which has broad application prospects in the preparation of micro and nano structures.
Polymer optical elements have widely been investigated because of their low cost and simple fabrication. Currently, UV-curable epoxy resins have been become general polymer materials for optical elements. However, they are still limited by their intrinsic properties, such as a relatively low rate of polymerization and high formulation viscosity. This paper proposed and demonstrated a rapid UV-curable process for polymer optical elements fabrication based on a UV-curable and low-viscosity thiol-ene composition. Several optical elements, including one-dimensional gratings with a 10-um period, Dammann Gratings and microlens arrays (100μm lens diameter), were fabricated by the UV-curable thiol-ene composition and their optical properties were examined in detail.
High performance infrared polarizer with broad band is required for various infrared applications. The conventional infrared polarizer, based on the birefringence effect of natural crystal, is cost-consuming in fabrication and can hardly be integrated into micro-optical systems due to its large bulk. In this paper, an infrared polarizer is proposed in the spectrum from 3 to 19 μm based on sub-wavelength metal wire grid. The dependence of the performance on some key parameters, including metal materials, geometrical parameters, has been deeply investigated by using the Finite-Difference Time-Domain (FDTD) method. The results show that Au wire-grids have a higher transmittance for the Transverse Magnetic（TM） mode light than that of other metal materials, and both the grid period and the grid thickness have important impact on the performance. Based on these observations, a polarizer has been designed by choosing the optimal value of related parameters. Numerical simulation suggests that the designed infrared wire grid polarizer have advantages of broad band, high TM polarization transmission efficiencies and high extinction ratios. The transmission efficiencies of TM polarization are larger than 59.3%, and the extinction ratios range from 28.6 to 44.6 dB in that range of the spectrum.