PART 6 • OPTICAL MEMS DESIGN

Where microns meet light

A single MEMS chip can steer over a million mirrors, each one flipping thousands of times a second, to project an image onto a screen.

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In this part, you'll learn why MEMS and optics are such a natural fit, and study a real device — Texas Instruments' Digital Micromirror Device — down to the physics of a single tilting mirror.

Key idea: A tiny mechanical tilt is enough to switch light on or off — that's the whole idea behind optical MEMS.

WHY MEMS FOR OPTICS?

A natural match

Right scale

The wavelength of light is on the same order of magnitude as MEMS device dimensions.

Low loss

Low optical insertion loss and low crosstalk between channels.

Scales well

Over 1 million mirrors on a single DMD chip.

Great for switching

A small displacement can produce a large optical effect.

Optics needs precise, tiny, fast-moving parts. MEMS was built for exactly that.

A LONG HISTORY

40 years of optical MEMS

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Optical MEMS has spanned four decades of development — from early tilting-mirror projection displays to the LiDAR scanners now guiding cars and mapping rooms in modern smartphones.

The same underlying idea — a tiny mirror, precisely controlled — powers both a 1990s projector and a 2020s LiDAR sensor.

WHERE THEY SHOW UP

Three kinds of optical MEMS

Light Control

Shutters, scanners, projection displays, fiber-optic switches, modulators

Sensing

Waveguide and fiber-optic sensors, confocal microscopes, pressure and flow sensors

Fabrication

Photostrictive actuators, Fabry-Perot mirrors, micro-lenses

Optical MEMS isn't just displays — it controls, senses, and even helps build other optical components.

THREE APPROACHES

Three ways to build a MEMS display

Reflective

TI's Digital Micromirror Device (DMD) — tiny tilting mirrors.

Diffractive

The Grating Light Valve (GLV) — moving diffraction-grating ribbons.

Interferometric

Qualcomm's mirasol — a resonant optical cavity.

Three completely different mechanisms, all solving the same problem: turning an electrical signal into a controlled point of light.

UNIT 21 STUDY COMPLETE

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Ready for the Fab Challenges?

You've covered Why Optical MEMS & Display Approaches.