A self-suspended MEMS film convertor for dual-band infrared scene projection

Abstract

A self-suspended MEMS film convertor used for infrared scene projection was proposed. The film convertor was based on a thin composite film with submicron thickness and high absorption of 95% in visible wavelength range. The microstructure arrays were fabricated by multiple lithography and dry/wet-etching processes to form 1300 × 1300 pixels. By optimizing the geometric parameters of the microstructure, the in-plane thermal diffusion distance was limited to 125 μm. The spatial resolution was therefore improved. Based on this MEMS film convertor, an infrared scene projector was built and its properties were tested. Illuminated by a 532 nm laser, an infrared image with the maximum apparent temperature of 489 K was obtained under the laser power density of 6.4 mW/mm2. By cooling to 278 K, the thermal rising and decay time constants were 5.02 and 2.76 ms, respectively. It indicated that infrared scenes would have a possible frame rate of higher than 100 Hz. The radiation spectrum was similar to a blackbody spectrum, which covered both 3–5 and 8–12 μm wavelength range. These unique properties of the MEMS film convertor made it an ideal candidate to be used in a hardware-in-the-loop simulation system for infrared imaging device performance evaluation.