• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1521-1527
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• 2000

A micromirror actuated by piezoelectric unimorph cantilevers is proposed as a tine-tracking device for high-density optical data storage. Bending motions of the metal/PZT/metal unimorphs translate an integrated micromirror along the out-of-plane vertical direction. The micromirror alters the optical path of the incident laser beam and linearly steers the reflected laser beam by its out-of-plane parallel actuation. 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 Gbitlin2 owing to the light mass of the micromirror. In this paper, preliminary characteristics of the micro-machined PZT actuated micromirror (PAM) are reported. Only a 360 nm-thick PZT film deposited by sol-gel process shows both good electrical and mechanical characteristics for the fine-tracking actuator. The micromirror can be easily actuated up to several micrometers under low voltage operation condition well below 10 volts.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.11
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• pp.748-754
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• 1999

Micromirrors supported by S-shape girders were fabricated and their angular deflections were measured using a laser-based system. A micromirror consists of a $50\mum\times50\mum$ aluminum plate, posts and an S-shape girder. Two electrodes were deposited on two corners of the substrate beneath the mirror plate. $50\times50$micromirror array were fabricated using the Al-MEMS process. The electrostatic force caused by the voltage difference between the mirror plate and one of the electrodes causes the mirror plate to tilt until the girder touches the substrate. Bial voltage of the mirror plate is between 25~35V and signal pulse voltage on both electrodes is $\pm5V$. A laser-based system capable of real-time two-dimensional angular deflection measurement of the micromirror was developed. The operation of the system is based on measuring the displacement of a HeNe laser beam reflecting off the micromirror. The resonant frequency of the micromirror is 50kHz when the girder touches the substrate and it is 25 when the micromirror goes back to flat position, since the moving mass is about twice of the former case. The measurement results also revealed that the micromirror slants to the other direction even after the girder touches the substrate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.380-384
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• 2010

A micromirror for a laser display system actuated by the electromagnetic force induced by the surface coil and the permanent magnet was designed and analyzed through the coupled physics analyses incorporating the electromagnetics, mechanics, and electrothermal analysis because the mechanical rotation of the micromirror is driven by the electromagnetic driving force. The proposed micromirror has two torsion beams to sustain the mirror plate which has surface coils on the top and the two permanent magnets exists on both sides of the micromirror for an external magnetic field source. The designed micromirror has the resonant frequency of 3.82kHz. When the magnetic field of the permanent magnet is 0.4T, the coil has 4 turns, and the current density of coil is 3.6A/$mm^2$, the estimated z axis displacement of the mirror plate edge is 0.23mm which corresponds to the rotation angle of $14.2^{\circ}$. When considering the joule heating in the current-carrying coil, the maximum temperature of the mirror plate is obtained as 300.045K, which induces the negligible changes in the rotation angle and the resistance of the coil.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.274-279
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• 2007

This study focuses on the enhancement of maskless photolithography as well as the peptide synthesis application with single crystalline silicon micromirrors. A single crystalline silicon micromirror array has been designed and fabricated in order to improve its application to the peptide synthesis. A micromirror rotates about ${\pm}\;9^{\circ}$ at the pull-in voltage, which can range from 90.7 V to 115.1 V. A $210\;{\mu}m-by-210\;{\mu}m$ micromirror device with $270\;{\mu}m$ mirror pitch meets the requirements of an adequately precise separation for peptide synthesis. Synthetic 16 by 16 peptide array corresponds to the same number of micromirrors. The large size of peptide pattern and the separation facilitate biochip experiments using fluorescence assay. The peptide pattern has been synthesized on the GPTS-PEG200 surface with BSA-blocking and thereupon the background was acetylated to reject non-specific bindings. Hence, an averaged slope at the pattern edge has been distinguishably improved in comparison to patterning results from an aluminum micromirror.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1159-1162
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• 2007

We have developed $16{\mu}m{\times}16{\mu}m$ digital micromirror array suitable for seamless-picture projection display system. This structure can improve the picture quality by making seamlesspicture image when combined with high-fill-factor microlens array to focus lights onto the mirror center. The fabricated micromirror shows excellent dynamic performances including the resonant frequency of 400 kHz.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.416-418
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• 1996

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using surface micromachining technology. $50{\times}50$ micromirrors are arrayed two dimensionally. The micromirror plate is supported by a vertical spring structure that is placed underneath the mirror plate. When the mirror plates reflect a light, the micromirror array un have large effective reflecting area. Fabrication of vertical spring uses only one mask and shadow evaporation process.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.288-294
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• 2002

This paper presents the design, fabrication and characterization of a 32 by 32 electroplated micromirror array on a glass, a low cost substrate. Approaches taken in this work for the fabrication of micromachined mirror arrays include a line addressing scheme, a seamless array design for high fill factor, planarization techniques of polymeric interlayers, a high yield methodology for the removal of sacrificial polymeric interlayers, and low temperature and chemically safe fabrication techniques. The micromirror is fabricated by aluminum and the size of a single micromirror is 200 $\mu\textrm{m}{\;}{\times}200{\;}\mu\textrm{m}$. Static deflection test of the micro-mirror has been carried out and pull-in voltage of 44V and releasing voltage of 30V was found.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.618-620
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• 1997

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using shadow evaporation process. The fabrication process is very simple with use of shadow evaporation process, and the micromirror array has a high fill-factor. The static and dynamic characteristics such as deflection angle vs. applied voltage, step response, and frequency response are measured using a contact free optical measurement technique. The downward threshold voltage was 8 V, step response time was $13.5{\mu}s$ when 32 V step voltage applied, and a resonance observed at 11kHz. The lifetime of micromirror with anti-stiction coating was tested and micromirror operated successfully over 200 million cycles of touch-down operations.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.263-266
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• 2006

An optical microphone was developed using a dual-core multi-mode fiber block and a membrane type micromirror. The fiber block serves as a compact optical head, and the micromirror as a reflective diaphragm. The micromirror is designed to be suspended through a silicon bar connected t a frame, allowing for displacement induced by acoustic waves. The optical head is implemented by integrating two multi-mode fibers in a single block, and used to transfer light signals between it and the diaphragm. For the assembled microphone, its static characteristics were observed to reveal the operating point defined as the optimum distance between the optical head and the diaphragm. And its dynamic response was tested to exhibit a frequency bandwidth of 3 kHz with the variation of $\sim5dB$.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2260-2262
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• 2000

In this paper, micromirror which can rotate 45 degree is designed, analyzed and fabricated. The micromirror is parallel to the substrate initially. When external magnetic field is applied, a micromirror can rotate to align its easy axis to the field. The size of micromirror array is $10{\times}10$. The mirror plate and spring is made of aluminium, and nickel is used as soft magnetic material. To obtain 45 degree angular deflection, dimension ratio between stopper length and thickness of sacrificial layer is properly selected. By using electrostatic force, individual actuation is possible.