Synthesis and Optical Properties of Ce-doped ZnO

ZnO nanorods were synthesized using the sol-gel method, and the effects of annealing temperature and Ce doping on the morphologies and optical properties of ZnO nanostructures were investigated in detail. The XRD measurements showed that the as-synthesized ZnO nanostructures had a hexagonal wurtzite structure. SEM images showed that uniform nanorods formed at 900 °C. Photoluminescence measurements showed an ultraviolet emission peak and a relatively broad visible light emission peak for the samples sintered at different temperatures. The UV emission peak bathochromically shifted when the annealing temperature rose from 850 to 1000 °C. Ce doping decreased the synthesized temperature of the ZnO nanorods to 500 °C, and the UV peaks hypsochromically shifted.

Design of a compact athermalized infrared seeker

In order to meet the application requirement of a certain long wavelength infrared （LWIR） seeker, a small volume, light weight and passively athermalized infrared OR） objective is designed in this paper. The two-lens telephoto struc- ture is adopted by merely using aluminum alloy as the housing material. By balancing the thermo-optical coefficient and thermal expansion coefficient of materials, an athermalized IR seeker with effective focal length of 90 mm and F number of 1.2 is achieved. The whole optical length is 75 ram, and the weight is only 234 g. The objective can remain fine imaging quality under temperature range from -40 ℃ to 60 ℃, which is beneficial to the lightweight design oflR seekers.

Design and preparation of a large size laser protective coating for solar arrays on spacecrafts

In this letter, we introduce the project of multilayer dielectric fihn based on conventional optics to design laser-protective coating. A desired material with an ideal refractive index is used to optimize the design results. Two film-thickness masks are designed to improve the uniformity of large-size coatings. Experimental results show that the average spectral transmittance from 400 to 1000 nm is higher than 85%, the attenuation of high-energy laser at both 532 and 1064 nm is larger than 98% in the range of ±20°, and the film uniformity of large area is more than 98.2%. The coating performance observed meets the requirements of both utilization of solar energy and laser protection.

Thermal analysis and an improved heat-dissipation structure design for an AlGaInP-LED micro-array device

This paper describes a novel finite element thermal analysis model for an AIGalnP-LED micro-array device. We also conduct a transient analysis for the internal temperature field distribution of a 5x5 array device when a 3x3 unit is driven by pulse current. In addition, for broader applications, a simplified thermal analysis model is introduced and its accuracy is verified. The internal temperature field distribution of 100xl00 units is calculated using the simplified model. The temperature at the device center reaches 360.6 ℃ after 1.5 s. In order to solve the heat dissipation problem of the device, an optimized heat dissipation structure is designed, and the effects of the number and size of the heat dissipation fins on the thermal characteristics of the device are analyzed.

Czerny-Turner imaging spectrometer for broadband spectral simultaneity

A modified asymmetrical Czerny-Turner arrangement with a fixed plane grating is proposed to correct aberrations over a broadband spectral range by analyzing the dependence of aberrations for different wavelengths. The principle of design is deduced in detail. We compare the performance of this modified Czerny-Turner imaging spectrometer with that of the existing Czerny-Turner arrangement by using a practical Czerny-Turner imaging spectrometer example. The excellent performance of the modified imaging spectrometer is confirmed by simulation with ZEMAX software.

Spontaneously deployable structure for space diffractive telescope

In order to satisfy the demands for diffractive telescopes in space exploration, a new deployable space diffractive tele- scope is designed. The structure and geometrical sizes of the spontaneously deployable telescope are preliminarily designated through the Serrurier truss principle and the optimized design theory. The finite element model of the de- ployable structure is established, and its deployed characteristics are analyzed. The prototype of the spontaneously de- ployable structure is constructed and some experiments are carried out to study its characteristics. Experimental results indicate that the deployable structure is 2.95 m in length, its repetitive deployed precision can reach less than 2 ram, the off-center error is less than 0.3 mm, and its deployed precision can be adjusted to micrometer level by actuators when it has deployed. It has simple structure, low mass, steady and reliable deployment, as well as higher precision for space diffractive telescopes.