Lawrence Livermore National Laboratory Background
Tip/tilt/piston (TTP) micro-mirror arrays have been a topic of significant interest since the 1980’s because of their ability to simultaneously direct multiple beams of light in various directions at high speeds (kHz). Applications, which drove the development of such arrays, included optical cross-connects, ultrafast wideband optical switches, beam stabilization, image projection, object tracking, adaptive optics for aberration correction and laser scanning/steering. Most existing TTP arrays can be categorized into five major types according to their actuation physics and reflecting surface geometry.
LLNL researchers have developed a high-speed, tightly-packed array of micro-mirrors capable of rapidly (>40 kHz) directing light over large angles (>10°) in two axes-tip and tilt-with continuous closed-loop motion control ().
LLNL’s TTP micro-mirror array design contains a number of unique features that enable its high performance. These features are generated from the application of precise constraint in the design of the flexures linking the mirror components together. Three flexural structures are utilized in the design, i) mirror guide flexures, ii) decoupling transmission flexures, and iii) actuator guide flexures.
All of these flexures are designed to only allow the desired degrees of freedom. The structure does not have any extra degrees of freedom, so all structural modes are directly controllable by the actuators. Nothing is ‘free’ to resonate along flexural directions of compliance during operation. This means the higher order harmonics of the structure are moved up to significantly higher frequencies, raising the operating speed.
LLNL’s flexure-based rotary comb drive tip-tilt micro-mirror array has a significantly higher performance in both range and speed over existing equipment, due to innovations in three areas: flexures, actuators and scaling. These performance gains enable a large variety of optically-based technologies with high value applications.
Applications for LLNL’s micro-mirror array include:
Fusion target tracking for high rate energy production
True-3D image generation for multi-threaded autostereoscopic displays and cloaking devices
High-speed confocal microscopy
High-speed gas detection sensors
Ultra-rapid multi-material 3D printing
Photonic computing and advances
Compact laser communications
Precision focusable LIDAR
Broad-spectrum ultrafast optical switching