A Varifocal Convex Micromirror Driven by a Bending Moment

J. Microelectromech. Syst.

2012

We present a varifocal scanning micromirror fabricated from a silicon-on-insulator wafer. The varifocal scanning micromirror consists of a varifocal mirror with a rotational scanning function. The scanner and varifocal mirror are driven by comb and parallel-plate electrostatic actuators, respectively. The mirror rotates 5.5 • at 45 V in static mode. The curvature of the varifocal mirror is changed from −4 m −1 (−128-mm focal length) to +5 m −1 (+93-mm focal length) by applying a voltage from 0 to 50 V. It is confirmed that the lateral position and spot size of the reflected laser beam from the varifocal scanning micromirror are changed simultaneously. Moreover, confocal sensing is demonstrated using a fiber-optic system with the proposed mirror.[2011-0307.R1]Index Terms-Comb-drive actuator, confocal microscope, electrostatic actuator, micromirror, scanner, silicon on insulator (SOI), varifocal mirror.

Section: Icroelectromechanical Systems (Mems)mentioning

confidence: 99%

Varifocal Micromirror Integrated With Comb-Drive Scanner on Silicon-on-Insulator Wafer

Sasaki

J. Microelectromech. Syst.

2012

“…Many kinds of scanning micro-mirrors have been investigated (Gianchandani et al 2008). On the other hand, varifocal micro-lens and varifocal micromirror are also attracting interests in the miniaturization of imaging systems (Kuiper and Hendriks 2004;Himmer et al 2001;Hokari and Hane 2009). In the recent report, the deformation of varifocal micro-mirror was improved for obtaining a precise parabolic shape by adjusting the voltages applied to the inner and outer electrodes (Himmer et al 2001).…”

Section: Introductionmentioning

confidence: 99%

“…In the recent report, the deformation of varifocal micro-mirror was improved for obtaining a precise parabolic shape by adjusting the voltages applied to the inner and outer electrodes (Himmer et al 2001). A precise convex parabolic deformation of micro-mirror was also generated by applying a bending moment at the circumference (Hokari and Hane 2009). However, there are few reports on the combination of micro-mirror scanner and varifocal micro-mirror on a Si chip for laser scanning systems (Shao et al 2004;Shao and Dickensheets 2005;Sasaki and Hane 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The varifocal mirror is designed on the basis of our previous study (Hokari and Hane 2009). A circular Si micro-mirror is suspended by some springs as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the varifocal mirror was studied in detail in our previous research (Hokari and Hane 2009). In this experiment, we improved the alignment between the Si and glass substrates.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Micro-mirror laser scanner combined with a varifocal mirror

Hokari

2012

Microsyst Technol

Self Cite

A laser beam scanning system consisting of a scanning micro-mirror and a varifocal micro-mirror is fabricated for laser beam sensing with variable beam diameter. The scanning micro-mirror is operated under the resonant oscillation condition with an electrostatic comb-drive actuator. The varifocal micro-mirror is driven by a bending moment generated at the circumference of mirror with a parallel-palate electrostatic actuator. The scanning micromirror and the varifocal mirror are fabricated on a silicon on insulator wafer. The rotational angle of 9°at 766 Hz is obtained at the voltage of 300 V. The spot size of the laser beam is adjusted from 0.5 to 3.5 cm at the distance of 43 m by changing varifocal voltage. The proposed scanning system can be useful for several sensing techniques.

Deformation of varifocal mirror with narrow frame by SOI wafer residual stress

Sasaki

2012

Elect Comm in Japan

Silicon-on-insulator (SOI) wafers are used for many micro-electro-mechanical systems (MEMS). The influences of residual stress of SOI wafer on the fabricated structures are important especially for micro-mirror because the optical performances are often affected by them. In this study, we propose an analytical calculation for the deformation of mirror and frame of a varifocal mirror. The deformations of the fabricated structures were measured using a white light interferometer. The frame was tilted at 2.8 mrad which was explained by the calculated value of 3.9 mrad. The mirror was deflected by 100 nm with the top-flat shape, which also agreed well with the proposed analysis.