Yi Xinjian

Fabrication and Characterization of Nanocrystalline VO2 Thin Films

Nanocrystalline VO2 films with phase transition temperature 34 degrees C have been fabricated on Si3N4-film-coated silicon and quartz substrates by argon-annealing films of metastable VO2(B). The original VO2(B) films are obtained by ion beam sputtering in an argon-oxygen atmosphere at 200 degrees C. The nanocrystalline VO2 films exhibit strong changes in electrical and optical properties when a phase transition is completed. The phase transition temperature in the as-fabricated samples is about 34 degrees C, which is smaller in comparison with 68 degrees C in the single-crystalline VO2 material. A lower phase transition temperature is favorable for device applications such as smart window coating and low power consumption optical switching.

Fabrication, Testing and Integration Technologies of Polymer Microlens for Pt/Si Schottky-Barrier Infrared Charge Coupled Device Applications

A novel polymer refractive microlens array has been formed on the surface of 256(V)×290(H) PtSi Schottky-barrier infrared charge coupled device (IRCCD) image sensors to improve the photoresponsivity of the IRCCD. The fabrication process flows of polymer microlens array are described. An effective aperture ratio in excess of 92% of microlens array has been achieved. An experimental facility to evaluate the optical performance of microlens array is introduced. The measurement results show that the microlens array indicates better than 4% non-uniformity of focal length and high optical performance. The application of the microlens array to improve the photosensitivity of infrared CCD is discussed.

Bionic ommatidia based on microlens array

A simple method is reported to manufacture a planar compound eye using a microlens array. The compound eye, inspired by insects, consists of a microlens array and a waveguide coupled with it. A microlens array with lenses of 50 µm in diameter is fabricated by melting AZ1500 photoresist and then transferring it onto SU-8. With the self-focus method applied, a waveguide array is formed, and each is exactly coupled to a lens. The formation of the waveguide is simulated using finite difference time domain (FDTD) arithmetic, resembling the ommatidia produced in our experiment. The ommatidia is also testified to astrict beam, just as the natural compound eyes do.

Inspection for electric power systems using uncooled infrared camera

Uncooled infrared camera for contactless temperature measurements of electric power systems has been described. The overheating problems in electric power systems have been demonstrated for measurements of one- and two-dimensional temperature fields. The diagnostic system consists of a PalmIR 250 camera, a handheld computer and related software. In this paper the one dimensional heat conductive equation of high voltage transmission and the relative solutions have been discussed which are agreeable with experimental measurements. The infrared inspection systems provide excellent image quality with temperature measurement accuracy of two percent of full scale.

Research on hybrid device of Si microlens arrays with long focus and IR detector arrays

A new method, named step simulation, is proposed to fabricate refractive 128/spl times/128 element Si microlens (MLS) arrays for hybrid integration with PtSi IR Focal Plane Arrays (FPAs). By the method, the focal length of rectangle-based multilevel Si MLS arrays is over 1 millimeter, much longer than typical focal length of MLS array fabricated by conventional binary optics Fresnel technique. Si MLS arrays and IR FPAs are coupled with infrared glue. The IR responsivity of the hybrid device is improved significantly.

The influence of annealing parameters on the structure and optical and electrical properties of VO/sub x/ films

Vanadium films have been deposited onto Si and quarts substrates by reactive ion-beam sputtering. The substrates are followed by annealing post-treatment. The treatment is performed in proper oxygen flow and temperature. The stoichiometry of thin films is measured by X-ray Photoelectron Spectroscopy (XPS) and X-Ray diffraction spectrum (XRD). The experimental results show that the VO/sub 2/ thin films have been formed by reactive ion-beam sputtering and annealing post-treatment, and that the resistivity change of VO/sub 2/ thin films by a factor larger than 10/sup 3/ can be obtained. It is evident that the annealing process is important to VO/sub 2/ thin films with excellent optical and electrical properties.