MEMS mirrors: The next big wave in MEMS technology
Microelectromechanical systems (MEMS) mirrors are making their way into new applications after decades of intensive development efforts.
A microelectromechanical systems (MEMS) mirror’s basic function is to deflect and move a focused beam of light upon exposure. The light beam can be moved along a single axis (one-dimensional mirror) or in two axes (two-dimensional mirror). (See Fig. 1.) This simple action of receiving and deflecting a focused beam of light is at the core of scanning technology that is experiencing growth in numerous applications, which was unthinkable until recently.
Three competing design methods for making MEMS mirrors
Technology for making MEMS mirrors matured during the last decade with three main competing design techniques, which are classified based on the driving principles used to move the mirrors. They are: electrostatic driving, electromagnetic driving, and piezoelectric driving. All three have pros and cons and a comparative summary of them is shown in Figure 2.
New applications
MEMS mirrors have been used mainly in a few applications such as optical switching in telecommunications, optical projectors, and specialty applications like biomedical optical coherence tomography (OCT). However, this is changing as new applications pop up constantly.
The capability of MEMS mirrors to move light is ingeniously used to create two basic groups of products that are driving the majority of new applications. The two groups of products are: Laser projectors for animated visual messaging and video projection, and LiDARs for three-dimensional (3D) perception sensing.
Laser projectors convert moving light into higher-level information for practical use as signs, graphics, and videos. The information itself can be presented in vector graphic laser projection (VGLP) mode or in raster mode, and the use of MEMS mirrors is critical for both. VGLP based on MEMS mirrors (MEMS VGLP) is currently garnering attention because of its ability to produce high-contrast images in daylight outdoor conditions, which creates a pathway to many new applications.
The makeup of one billion units by market segments is shown in Figure 5. The highest unit volumes are for automotive applications, where MEMS LiDAR in ADAS with Robotaxi, dynamic laser headlights, and heads-up display will take a market share of more than 20%. This will amount to hundreds of millions of units for automotive applications alone.
