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Micro scanning mirrors are quite versatile MEMS devices for the deflection of a laser beam or a shaped beam from another light source. The most exciting application is certainly in laser-scanned displays. Laser television, home cinema and data projectors will display the most brilliant colors exceeding even plasma, OLED and CRT. Devices for front and rear projection will have advantages in size, weight and price. These advantages will be even more important in neareye virtual displays like head-mounted displays or viewfinders in digital cameras and potentially in UMTS handsets. Optical pattern generation by scanning a modulated beam over an area can be used also in a number of other applications: laser printers, direct writing of photo resist for printed circuit boards or laser marking and with higher laser power laser ablation or material processing. Scanning a continuous laser beam over a printed pattern and analyzing the scattered reflection is the principle of barcode reading in 1D and 2D. This principle works also for identification of signatures, coins, bank notes, vehicles and other objects. With a focused white-light or RGB beam even full color imaging with high resolution is possible from an amazingly small device. The form factor is also very interesting for the application in endoscopes. Further applications are light curtains for intrusion control and the generation of arbitrary line patterns for triangulation. Scanning a measurement beam extends point measurements to 1D or 2D scans. Automotive LIDAR (laser RADAR) or scanning confocal microscopy are just two examples. Last but not least there is the field of beam steering. E.g. for alloptical fiber switches or positioning of read-/write heads in optical storage devices. The variety of possible applications also brings a variety of specifications. This publication discusses various applications and their requirements

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This paper discusses the fracture strength study of torsion springs in MEMS microscanners, which are fabricated in silicon-on-insulator (SOI) with deep-reactive-ion-etch (DRIE) process. High performance microscanners are of particular interest for scanning laser projection displays. To produce high resolution images, scanners are required to rotate with large actuation angles (>10 degrees mechanical angle) at designated resonant frequencies. While the designs are pushed closer to material limits, it is essential to acquire knowledge of single-crystal-silicon's fracture strength. We have designed samples for fracture strength tests, which reach failure angle (> 20 degrees) with low driving voltage (< 50 volts) under vacuum. The tests are performed with real-time optical feedback to ensure resonance operations. A voltage ramp is applied to scanners until fractures occur; the ramp-rate and starting angle are chosen such that failures occur within thirty minutes of operation. Torsional stresses at fracture are calculated from failure angles via an ANSYS® model. In the experiment, forty samples from two spring designs with a cross-section of 14x30 um and a length of 240 um are tested. Because fracture angles scatter around a mean value, Weibull statistics is used to treat the characteristic behaviors of the tested samples to better interpret the test results. The Weibull characteristic fracture strengths are 2.97 GPa and 2.58 GPa. With a stress limit of less than 2 GPa, we can achieve a 86% reliability SVGA microscanner design with a 1 mm diameter, a 32 KHz resonance frequency, and a single-side mechanical scan angle of 13 degrees