A MEMS (Micro-Electro-Mechanical Systems) scanning mirror is a key component in laser projection systems. It is used to steer a laser beam rapidly and accurately across a two-dimensional surface, enabling the creation of images and patterns with high resolution and brightness. The operation of a MEMS scanning mirror involves the use of micro-scale mechanical structures that can be electrostatically or electromagnetically actuated.
Here's a general description of the operation of a MEMS scanning mirror for laser projection:
Mechanical Structure: The MEMS scanning mirror consists of a tiny mirror mounted on a micro-scale mechanical structure, which is typically made from silicon or other materials with excellent mechanical properties. The mirror is often square or rectangular in shape, and its dimensions can range from a few hundred micrometers to a few millimeters.
Electrostatic or Electromagnetic Actuation: There are two common methods used to actuate the MEMS scanning mirror: electrostatic and electromagnetic.
Electrostatic Actuation: This method involves applying an electrostatic force between the mirror and fixed electrodes placed around it. By varying the voltage between the mirror and the electrodes, the mirror experiences a force that causes it to tilt or rotate in a controlled manner.
Electromagnetic Actuation: In this approach, the MEMS scanning mirror is surrounded by electromagnetic coils. By passing current through these coils, a magnetic field is generated, which interacts with the mirror's structure. This interaction induces mechanical movement, allowing precise control of the mirror's position.
Control Electronics: The MEMS scanning mirror is controlled by dedicated electronics that provide the necessary signals to actuate the mirror. These control electronics can be part of a larger system, such as a laser projector, which sends image data to the mirror for projection.
Raster Scanning: To create a complete image, the MEMS scanning mirror rapidly sweeps the laser beam back and forth in a raster pattern across the projection surface. The control electronics adjust the mirror's orientation at high speeds to ensure accurate scanning and smooth image display.
Optical System: The MEMS scanning mirror is typically integrated into an optical system, including laser sources, lenses, and possibly other mirrors, to direct and focus the laser beam onto the projection surface. The mirrors' movement allows for precise positioning of the laser beam, enabling the formation of different shapes, patterns, and images.
Image Rendering: The image to be projected is divided into small segments or pixels, and each pixel's intensity is modulated based on the corresponding mirror's position and orientation during scanning. By combining the movements of the mirrors and modulation of the laser intensity, a complete image is projected onto the surface in real-time.
Overall, MEMS scanning mirrors offer high-speed, precise, and efficient laser beam steering, making them an essential component in various applications, including laser projectors, laser displays, and laser-based 3D scanning systems.