Sang-Cheon Kim

An electrostatic scanning micromirror with diaphragm mirror plate and diamond-shaped reinforcement frame

We present the design, fabrication and measurement results of a comb-driven electrostatic scanning micromirror. Instead of a conventional micromirror having uniform thickness across the entire reflective surface, a diaphragm mirror plate supported by an array of diamond-shaped frame structures is fabricated monolithically. The fabrication process is a simple sequence of silicon deep etch processes on both sides of the silicon-on-insulator (SOI) substrate without the substrate bonding process. The micromirror is fabricated on the device layer of the substrate. The mirror plate undergoes a rotational motion by an electrostatic force between the movable comb electrodes connected to the micromirror and stationary comb electrode formed on the handle wafer. A scanning micromirror with a 10 µm thick diaphragm mirror plate, having a planar dimension of 1.5 × 1.5 mm2, supported by an array of 110 µm thick rhombic support frames, was fabricated and tested. A mechanical deflection angle of 8.5° at a resonance frequency of 19.55 kHz and a pressure of 7 mTorr was obtained. A prototype of the raster scanning laser projection display system was developed using the fabricated micromirror as the horizontal scanner and a galvanomirror as the vertical scanner, respectively.

Electromagnetic Two-Dimensional Scanner Using Radial Magnetic Field

In this paper, we present the design, fabrication, and measurement results of a two-dimensional electromagnetic scanning micromirror actuated by radial magnetic field. The scanner is realized by combining a gimbaled single-crystal-silicon micromirror with a single turn electroplated metal coil, with a concentric permanent magnet assembly composed of two concentric permanent magnets and an iron yoke. The proposed scanner utilizes the radial magnetic field rather than using a lateral magnetic field oriented 45deg to the horizontal and vertical scan axes to achieve a biaxial magnetic actuation. The single turn coil fabricated with electroplated copper achieves a nominal resistance of 1.2 Omega. A two-dimensional scanner with mirror size of 1.5 mm in diameter was fabricated. Maximum optical scan angle of 8.8deg in horizontal direction and 8.3deg in vertical direction were achieved. Forced actuation of the gimbal at 60 Hz and resonant actuation of the micromirror at 19.1-19.7 kHz provide slow vertical scan and fast horizontal scan, respectively. The proposed scanner can be used in raster scanning laser display systems and other scanner applications.

Dual-Axis Electromagnetic Scanning Micromirror Using Radial Magnetic Field

This paper presents the design, fabrication and measurement results of a dual-axis electromagnetic scanning micromirror utilizing radial magnetic field. The scanner is comprised of a gimbaled single-crystal-silicon micromirror with a single turn electroplated metal coil, assembled passively above a concentric permanent magnet assembly. Proposed scanner utilizes the radial magnetic field rather than using the magnetic field oriented 45 ° to the horizontal and vertical scan axes to achieve a biaxial magnetic actuation[ 1,2]. Forced actuation of the gimbal and resonant actuation of the micromirror provide slow vertical scan and fast horizontal scan respectively. A dual-axis scanner with maximum scan angle of 16.1 °, mirror size of 1.5 mm in diameter, and resonant frequency of 19.7kHz is reported.

Micro-Optical Fiber Coupler on Silicon Bench Based on Microelectromechanical Systems Technology

A microelectromechanical systems (MEMS)-based, micro-optical fiber coupler to obtain a high power laser diode beam is integrated with a fiber rod lens and an array of SU-8 lenses, through each of which the laser beams emitted from the laser diodes are collimated vertically and horizontally, respectively, thus increasing the coupling efficiency. The fibers bundle and the laser diodes are assembled in one package on a silicon optical bench. The optical properties of the SU-8 lenses are suitable for high power laser diode application. The collimation of the beams passing the rod lens and the SU-8 lenses was confirmed. According to the simulation and experimental results, the coupling efficiency of the fiber coupler was increased by the insertion of the SU-8 lenses when the emitter width of the laser diode was wide.

Performance of a raster scanning laser display system using diamond shaped frame supported micromirror

We describe the design, fabrication, and experimental results of a raster scanning laser display system using micromachined electrostatic scanning micromirror. The micromirror is comprised of a diaphragm mirror plate supported by an array of diamond shaped support frame, and movable comb electrodes. A prototype raster scanning laser display system using the fabricated micromirror, having optical scan angle of 16.9deg at resonance frequency of 19.55 kHz, as the horizontal scanner was developed and tested. To compensate for the nonlinear characteristics of the scanner, a simple image correction method was developed, and the projected image was analyzed and compared with the simulation results

Diamond shaped frame supported electrostatic scanning micromirror

The paper presents the design, fabrication and measurement of an electrostatic scanning micromirror having a diaphragm mirror plate supported by an array of diamond shaped frame structures. Instead of supporting the diaphragm mirror of a different material with a stiff rim structure at the circumference, the diaphragm mirror plate and the frame structure are fabricated monolithically in the same layer of single-crystal-silicon (Nee, J.T. et al., Proc. IEEE Int. Conf. MEMS, p.704-9, 2000). The scanning micromirror with a 10 /spl mu/m-thick diaphragm mirror plate, having a planar dimension of 1.5/spl times/1.5 mm/sup 2/, supported by an array of 110 /spl mu/m-thick rhombic stiffening frames, was fabricated and tested. A mechanical deflection angle of 8.5/spl deg/ at the resonance frequency of 19.55 kHz and 44% reduction of dynamic deformation (Conant, R.A. et al., Proc. IEEE/LEOS Int. Conf. Optical MEMS, p.49-50, 2000), in comparison to the conventional rectangular parallelepiped micromirror, were obtained.

Ultrasmall optical pickup module

For the application to the 5mm height optical drive, we have developed a small optical pick-up module within its dimension of 3.0×2.0×5.5mm, by integrating refractive and diffractive optical elements with laser diode and photo diodes assembly.

Ultra small optical pick-up module

We have developed a small optical pick-up module within its dimension of 3.0X3.0X5.5mm by integrating refractive and diffractive optical elements with laser diode and photo diodes assembly.

P‐118: Viewing Angle Improvement of TN Mode by HD Layer Inside LC Cell and a Compensation Film

Holographic diffuser(HD) layer inside LC cell was demonstrated, for a transmissive LCD of TFT-array on Color Filter structure. Master pattern of this layer was generated by holographic method and this pattern was replicated by stamping the master pattern on UV resin. Combined with a compensation film, TN-mode LCD with this layer showed improved viewing angle characteristics, especially along the up-down direction.

Real-time focal spot profiling for the adjustment of the focus in near field recording system

The tolerance of the optical components in the near-field recording (NFR) system is analyzed. The system uses a solid immersion lens (SIL) for near-field recording and an air bearing slider to maintain the near-field gap between the SIL and a magneto-optic (MO) disk. From the analysis, it is found that some of the components have a sub-micrometer level tolerance, which is unsuitable for practical application. To loosen this tight tolerance, the position of the collimator lens (CL) is adjusted according to the assembly state. The state of the assembly is detected in real time from the intensity-profile signal that is generated through a developed technique. Therefore, by monitoring the signal carries out the adjustment of the CL. The performance of the technique is evaluated through numerical calculation and the experiment is carried out in the developed NFR system.