A New Method to Analyse Two-Side Tapered Waveguides

We discuss the characters of two-side tapered waveguides. Then, based on some approximations, a simple but practical and efficient method is developed to design the taper waveguide. The results are compared with other methods in a good agreement.     

Development of MEMS-based micro capacitive tactile probe

In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon technique. Based on the sensor, a micro capacitive tactile probe is constructed by stylus assembly and packaging design for dimension metrology on micro/nano scale, in which a data acquiring system is developed with AD7747. Some measurements of the micro capacitive tactile probe are performed on a nano positioning and measuring machine （NMM）. The measurement results show good linearity and hysteresis with a range of 11.6 μm and resolution of better than 5 nm. Hence, the micro capacitive tactile probe can be integrated on NMM to realize measurement of micro structures with nanometer accuracy.     

折叠翼面展开过程中气动载荷特性数值模拟

针对某飞行器翼面高速展开过程,采用定常和非定常数值模拟两种不同方法,进行折叠翼面展开过程气动载荷分析研究,其中定常方法主要研究翼面从折叠到展开过程中不同展开角下外翼面的气动特性,分析展开角、来流参数对外翼面气动力的影响;非定常方法主要模拟折叠翼面展开角速度变化,从而获得典型工况下翼面展开过程的载荷情况,分析非定常效应对气动载荷的影响.研究发现,当翼面展开速度与来流速度相近时,则非定常效应不可忽略而必须采用非定常模拟方法.      

Nano-Traceability Study of a Cr Standard Grating Fabricated by Laser-Focused Atomic Deposition

A dimensional artifact is developed, which is a chromium （Cr） deposition grating fabricated by a laser-focused atomic deposition technique. The mean pitch of the grating is measured by using a metrological atomic force microscope with a large range, where a series of reference signs have been performed to locate the deposition area. Cosine error of the measurement result is analyzed and eliminated by the iterative angle calibration. The measurement result shows that the mean pitch of the grating is 212.66 ±0.02nm, which is very close to half of the standing laser wavelength （λ = 425.55 nm）. This means that the grating has traceability with high accuracy and can substitute the laser interference technology for instrument calibration. Moreover, using the Cr deposition grating as a nano standard can shorten the traceability chain and improve the practical application.     

Switchable down-, up- and dual-chirped microwave waveform generation with improved time-bandwidth product based on polarization modulation and phase encoding

A switchable down-, up- and dual-chirped microwave waveform generation technique with improved time-bandwidth product (TBWP) is proposed and demonstrated based on a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) cascaded with a polarization modulator (PolM). By properly controlling the phase shifts of the radio frequency signals applied to the DP-DPMZM, switchable down-, up- and dual-chirped waveforms with simultaneous frequency and bandwidth doubling can be generated. To enlarge the TBWP further, splitting parabolic signal and phase-encoding splitting parabolic signal are used to drive the PolM for the enhancement of bandwidth and time duration. Numerical results demonstrate the generation of down-, up- and dual-chirped microwave waveform with TBWP of 8, 160 and 10240. The proposed method may find applications in future multifunction radar systems due to the high performance and flexibility.