Dr. Siyuan He Profile

Dr. Siyuan He

at Univ of Toronto

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Proceedings Article | 25 October 2004 Paper

Repulsive force actuated rotary micromirror

Siyuan He, Ridha Ben Mrad

Proceedings Volume 5602, (2004) https://doi.org/10.1117/12.570271

KEYWORDS: Micromirrors, Actuators, Mirrors, Space mirrors, Prototyping, Surface micromachining, Numerical simulations, Microfabrication, Standards development, Sensors

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In this paper, a novel repulsive force based rotary micromirror is proposed. A repulsive force is produced in the rotary micromirror and the mirror plate is pushed up and away from the substrate. Therefore the rotation angle of the micromirror is not limited to the space underneath the mirror plate and thus the "pull-in" effect is completely circumvented. The novel rotary micromirror can achieve a large rotation angle with a large mirror plate. In addition the novel micromirror has a very simple structure and can be fabricated by standard surface micromachining technology. Numerical simulation is used to verify the working principle of the novel micromirror. A prototype of the novel rotary micromirror is fabricated by a commercially available surface microfabrication process called MUMPs. The prototype has a mirror size of 300μm x 300μm. The experimental measurements show that the prototype can achieve a mechanical rotation of 2.25 degrees (an optical angle of 4.5 degrees) at a driving voltage of 170 volts. A conventional surface micromachined attractive force based rotary micromirror of the same size can only achieve an angle of 0.1~0.2 degree.

Proceedings Article | 30 September 2003 Paper

Development of a novel translation micromirror for adaptive optics

Siyuan He, Ridha Ben Mrad

Proceedings Volume 5264, (2003) https://doi.org/10.1117/12.515063

KEYWORDS: Micromirrors, Prototyping, Mirrors, Surface micromachining, Adaptive optics, Optical fabrication, Modulation, Space mirrors, Electrodes, Microopto electromechanical systems

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Conventional translation micromirrors for adaptive optics use attractive electrostatic force and therefore have two limitations: 1) the stroke is limited to less than one third of the initial gap distance between the mirror plate and the substrate. Normally the stroke is in the range of submicrometers; 2) stiction happens during operation. A novel translation micromirror, which uses a repulsive electrostatic force, is presented in this paper. This novel translation micromirror completely overcomes the limitations associated with conventional translation micromirrors and its stroke is not limited by the initial gap distance between the mirror plate and the substrate and therefore is able to achieve a much larger vertical stroke to modulate lights over a wider spectrum than that achieved by conventional translation micromirrors. The novel translation micromirror has no stiction problem and is highly compatible with mature surface micromachining technology. An analytical model is derived for the novel translation micromirror and prototypes are fabricated. The prototype of the novel translation micromirror, which is deliberately not optimized so it could be fabricated using MUMPS, achieved a vertical stroke of 1.75μm using a driving voltage of 50 volts, which is three times the stroke of conventional MUMPS translation micromirrors. It is expected that if standard surface micromachining is used instead of MUMPs, the design of the novel translation micromirror can be optimized and a much larger vertical stroke can be achieved.

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