Optical Questions & Answers

What is a MEMS mirror?

MEMS stands for micro-electro-mechanical systems, and a MEMS mirror is a small moving mirror etched on a silicon wafer using MEMS technology. By using a MEMS mirror, you can reduce the size of the whole scanner to a few cm cube.

How are resonant and linear mirrors different?

A resonant mirror moves in a continuous sinusoidal motion at the fixed frequency, usually 1 kHz to tens of kHz. You can get a wide mirror angle with a small driving electric current. For example, our S13989-01H resonant mirror is capable of +/-20 deg. optical angles with +/-25 mA driving current.

A linear mirror tilts its angle according to the driving current. You can stop the mirror at the desired angle or operate it in continuous movement. However, in continuous mode the speed is usually limited to tens of Hz.

Why do you need a feedback loop for the resonant axis frequency?

The mirror’s tilt angle is significantly affected by even a slight shift in the resonant frequency. The resonant frequency can shift over time and when the temperature changes. The feedback loop adjusts the mirror driver frequency to match the shifted resonant frequency, so it can minimize the tilt angle instability.

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Meet the engineers

Mario is a MEMS mirror applications engineer. A music enthusiast, his keen interest in audio systems and electric guitar drew him to electrical engineering. Sound analysis of shamisen, a Japanese musical instrument, was the focus of his graduate studies. Mario still enjoys music-related hobbies such as building audio speakers, playing the jazz guitar, and salsa dancing.

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