Thermal Imaging Devices Based On Micro-mechanical Optical Modulator

Infrared (IR) reconnaissance and detection is a key technology with a wide spectrum of application; however, high price of JR cameras has limited the application to a few selected areas. To achieve inexpensive JR detectors with high performance, many efforts have been involved in the exploration of new technologies, among which micromachined IR imaging arrays with optical readout systems are the most promising candidates. A kind of novel micromachined thermal imaging device, light modulating thermal image device (LMTID), that can be employed in all-light-processing thermal imagers is presented in this thesis, having advantages such as high sensitivity, high fill factor, short response time, high display brightness, small volume, and low power consumption. ?Two kind of design on light modulating thermal image device are posed originally in this thesis, and theoretical calculation and finite element simulation are performed for them. Cantilever models are suggested for the two kind of LMTID, then the sensitivity, the minimum detectable power and the response time of LMTID are estimated with simplified beam theory, and the thickness ratio of bimaterial beams are optimized. Static finite element analysis with ANSYS 5.4 program gives the sensitivity of LMTID, while dynamic analysis gives the thermal response time. Three-layer-structured LMTID can achieve a sensitivity of O.O3mIW and a response time of 6ms, while two-layer-structured LMTID can achieve sensitivity up to O.OO895m1W and corresponding response time of 3.6ms. These results demonstrate the potential high performance of LMTID compared with conventional JR detectors. ?The fabrication of LMTJD is a technological challenge, which includes two parts of contents, micromachining process and chip package. On micromachining side, LMTID chips based on AlfPoly-Si material combination were firstly fabricated using poly-Silicon a micromachining technology, in which primary issues of residual stress and capillary effect coming from wet release were addressed. Super critical CO2 drying technology was applied to the drying of the devices ?iii ? 4~眫ti~ successfully. On the base of poly-silicon micromachining technology, a kind of novel surface micromachining technology, silicon-sacrificial-layer surface micromaching, is presented in this thesis. With advantages of less process steps, surface auto flatting, and sacrificial layer thickness adjustable over rather a wide range, silicon-sacrificial-layer surface micromaching technology is favorable for the fabrication of LMTID. LMTID samples based on Al/S i02 material combination were made successfully using silicon-sacrificial-layer surface micromaching technology, which have shown great uniformity in their microstmctures. It is demonstrated that this micromachining technology can ensure not only the fabrication of functional samples, but also the production of future large format devices. The package of LMTID benefits a lot from the wirelessness of LMTID. Package with brass shell is applied to test samples successfully. ?Optical design and realization concerned with LMTID is...