ABSTRACT
Optical applications of MEMS (microelectromechanical systems) date back to the early stage of silicon micromachining, when a bit-map image projector was demonstrated using an array of 50 micron-size tilt mirrors in 1975 [1]. A review paper on silicon micro mechanisms published in 1982 covers a combination of a miniaturized Galvano scanner and an array of electrostatic cantilevers, both developed by the anisotropic wet etching of single crystalline silicon [2]. Later, in the 1990s, an electrostatic micromirror array was made on top of integrated circuits to construct an electrically addressable digital mirror device (DMD), which is called a digital light processing (DLP) device today [3]. A similar integrated mirror device was also reported as a pattern generator for maskless photolithography [4]. In recent years, MEMS technologies have been used to develop electrostatic tunable gratings and shutters as a light-valve array [5–7]. Various types of micro-optical scanners of both one- and two-degrees-of-freedom have been studied to construct a compact package of laser scanning displays (LSDs), which is usually referred to as a pico projector in the field of consumer electronics. Similar technology is also used to develop head-mount type displays [8].
