Tham khảo tài liệu 'micromechanical photonics - h. ukita part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fabrication 151 2. a Si-based negative resist with high resistance to oxygen reactive ion-beam etching O2 RIE is spin-coated onto the polyimide layer and exposed to an electron beam 3. the polyimide layer is etched down to the Si substrate by O2 RIE 4. after removal of the resist the microrotor are freed from the substrate by ultrasonic vibration. Fluorinated polyimide has a density of and a refractive index of at a wavelength of pm as listed in Table . Microphotoforming In order to increase the optical torque of the rotor it is effective to adopt a 3-D structure with slopes on its upper surface. To fabricate such 3-D microstructures photoforming is Ễ ypllẽ cl. However. 11e presently po pos I fhoiiooitmiinu apparatus is large and requires a special laser beam ultra-short-pulsed nearinfrared Ti sapphire or special resin two-photon-absorbed urethane material . We developed a desktop microphotoforming apparatus using a DVD optical head and a visible light-curable resin DF-200N Nippon Kayaku Corp. both of which are commercially available . Since the microstructure is generated by scanning a focused laser beam to solidify the contour of a liquid photopolymer the resolution is determined by the laser beam intensity distribution and the absorption of light within the polymer. To decrease the solidified depth a thin resin film was made using a ppmner as shown ìn Fig. Figure shows the shuttlecock optical rotor with a 30 pm diameter and 15pm thickness. The fabrication conditions were a scan speed of 25pills f scan pitch of pm single scan and a laser power of mW. The overall time was 12 min to fabricate 16 rotors. Fig. . Schematic diagram a and photograph b of the spineer-tpee liii-crophotoforming apparatus X stage Y stage Resin Spinner Z stage Optical head 152 4 Optical Rotor 3000 0030 oooo 0003 Fig. . Shuttlecock optical rotors 30pm diameter and 15 pm thick fabricated by photoforming Table . .
