In this paper, we suggest a polishing head with a mechanical gimbals-like structure for the optics fabrication. In the small tool polishing processes, several types of polishing mechanism have been tried to get more deterministic and high efficient optical fabrication. The conventional polishing processes to use the contacting pad material of polyurethane or pitch need the higher polishing rate to shorten the overall polishing time for large optics. Therefore, new polishing head mechanism is designed to use the air backpressure and gimbals-like hinge structure to increase polishing velocity. In the following experiment, mechanical adaptability was confirmed both on the flat glass and the convex aluminum surface.
The design, fabrication, and preliminary test results of a microelectromechanical, micromachined spatial light modulator (μSLM) with complementary metal-oxide semiconductor (CMOS) electronics, for control of optical phase is presented in this paper. An array of 32×32 piston-motion MEMS mirror segments make up the μSLM. Each mirror segment will be capable of altering the phase of reflected light by up to one wavelength for infrared illumination (? = 1.5 μm). The mirror segments are fabricated from metal in a low temperature process allowing for vertical integration of the μSLM with CMOS based, multi-bit, control electronics. The surface of the CMOS is planarized to facilitate μSLM-CMOS integration. The fabrication process and process development results, test results, including frequency response and electromechanical characterization of the (μSLM) actuators, will be presented.
This paper describes a planarization procedure to achieve a flat CMOS die surface for the integration of a MEMS metal mirror array. The CMOS die for our device is 4 mm × 4 mm and comes from a commercial foundry. The initial surface topography has 0.9 μm bumps from the aluminum interconnect patterns that are used for addressing the individual micro mirror array elements. To overcome the tendency for tilt error in the planarization of the small CMOS die, our approach is to sputter a thick layer of silicon nitride (2.2 μm) at low temperature and to surround the CMOS die with dummy pieces to define the polishing plane. The dummy pieces are first lapped down to the height of the CMOS die, and then all pieces are polished. This process reduces the 0.9 μm height of the bumps to less than 25 nm.
Design, microfabrication, and integration of a micromachined spatial light modulator ((mu) SLM) device are described. A large array of electrostatically actuated, piston-motion MEMS mirror segments make up the optical surface of the (mu) SLM. Each mirror segment is capable of altering the phase of reflected light by up to one wavelength for infrared illumination ((lambda) equals 1.5 micrometers ), with 4-bit resolution. The device is directly integrated with complementary metal- oxide semiconductor (CMOS) electronics, for control of spatial optical wavefront. Integration with electronics is achieved through direct fabrication of MEMS actuators and mirror structures on planarized foundry-type CMOS electronics. Technical approaches to two significant challenges associated with manufacturing the (mu) SLM is discussed: integration of the MEMS array with the electronic driver array and production of optical-quality mirror elements using a metal-polymer surface micromachining process.
The progress and current status of HgCdTe infrared detector in Korea during the last ten years is reviewed and future perspectives of infrared detector research and development are also given. The research and development of HgCdTe infrared detector was started in 1987. In the first five years, we had focused on the material growth, especially liquid phase epitaxy (LPE) by slider method and single element MWIR photovoltaic detector with large active area was realized with this LPE material. After that, the development of the linear array infrared detectors including photoconductive and photovoltaic devices was initiated and will be finished very soon. During this period we developed the travelling heater method (THM) for the use of the linear arrays. On the other hand MBE growth of HgCdTe was started for a specific applications and MOVPE process was employed for the two-color infrared development. Focal plane array program will be initiated very soon.
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