Laser display with single‐mirror MEMS scanner

Abstract

While arrayed DMD and LCD microdisplays are well-established approaches for visualization tasks, image-forming laser scanners are an emerging technology used to build miniaturized projection displays. A directly modulated RGB-laser module consisting of diode lasers for red and blue and a frequency-doubled semiconductor laser for green with color combining optics form the light source for the laser scanner have been developed. Subsequent beam-shaping optics suppresses unwanted stray light and enables optimum illumination of the scanning mirror. The MEMS device features a single scanning mirror oscillating in two directions in resonant mode. This requires appropriate data delivery realized by a custom-made driving logic, which converts the pixel stream originally arranged in rows and columns to the Lissajous-like spot trajectory on the screen. Additionally, the increased image brightness at the vertical and horizontal borders of the field of view (FOV) is also compensated by the modulation of laser power. Theoretical investigations of the resulting maximum achievable system transmission are presented. Different systems, such as an extremely miniaturized monochrome projection head with an integrated diode laser and a full-color projector have been realized. Important problems to be tackled are fast analog modulation of the laser power with high resolution and improved suppression of stray light and speckle

Micro-LEGO for MEMS

“…In particular, microelectromechanical systems (MEMS) represent an effort of this evolutionary engineering and have enabled many types of sensors, actuators, and systems to be reduced in size, exploiting microfabrication while often improving device performance [2]. For example, MEMS has miniaturized mechanical switches [3,4,5,6,7], chemical and physical sensors [8,9,10,11,12], display mirrors [13,14,15,16,17,18], and power generators [19,20,21,22]. A typical microfabrication process for MEMS encompasses photolithography to form a masking layer for subsequent processes, physical and chemical deposition to create a target material layer, and dry or wet etching to pattern the deposited layer.…”

Frequency selection rule for high definition and high frame rate Lissajous scanning

“…Controlled steering of laser beams attracts assorted optical applications such as advanced optical microscopy 1 , 2 , 3D material processing 3 , 4 including 3D printing 5 , 6 , single-pixel camera 7 , or screen-less display 8 – 10 . Recently, compact laser scanners become actively engaged in miniaturized imaging 11 – 15 or pico-projection display 16 , 17 systems. Laser microscanners such as microelectromechanical systems (MEMS) mirror scanners 18 and resonant fiber piezoelectric tube (PZT) scanners 14 , 19 are actively utilized for compact optical applications.…”

A gimbal-less two-axis electrostatic scanner with tilted stationary vertical combs and serially connected springs via a microassembly process

“…[1]. The one-axis scanner has evolved into the two-axis scanner to meet the requirements of optical systems such as projection displays [2][3][4], optical communications [5], laser ablation systems [6], and biomedical imaging [7][8][9][10]. Among the actuation methods of MEMS scanners, electrostatic actuation is attractive as it enables a compact size, low power consumption and simple fabrication.…”