See-Hyung Lee

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.

PZT actuated micromirror for nano-tracking of laser beam for high-density optical data storage

A micromirror actuated by piezoelectric cantilevers is proposed as a fine-tracking device for high-density optical data storage. Metal/PZT/metal thin film actuators translate an integrated micromirror along the out-of-plane vertical direction. The parallel motion of the micromirror steers linearly the optical path of the reflected laser beam. Numerical analysis shows that the actuated micromirror can satisfy the tracking speed imposed by the requirement on the access time for the high-density optical data storage up to few tens Gbit/in/sup 2/. In this paper, preliminary characteristics of the micromachined PZT actuated micromirror (PAM) are reported. The design and the fabrication process of the PZT actuated micromirror are described. Only a 3600 /spl Aring/-thick PZT film deposited by sol-gel process shows both good electrical and mechanical characteristics for the actuators. The micromirror can be easily actuated up to several micrometers under low voltage operation condition.

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.

MEMS technology for optical data storage

MEMS technology is fast becoming the new enabling technology for areas that require the performance and cost advantages it brings. In this paper, as one of its promising application areas, MEMS technology for a ultra small optical pickup module is presented. The optical flying head is constructed by integration of micromachined devices such as micro slider, micro coil, microactuator, and micro lens within 0.5 mm in height. The basic optical unit comprised of refractive and diffractive optical elements including LD, PD, polarizers, and collimating lens is built by wafer level stacking within its dimension of 3.0/spl times/3.0/spl times/5.5 mm/sup 3/. By assembling of the optical flying head and the basic optical unit onto a swing arm, it is possible to obtain an ultra small pickup system which can be applied in mobile environment.

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.