Small optical devices can be valuable as diagnostic imaging tools within the body, for instance, as optical probes with a 360-degree view in the gastrointestinal tract. A new microelectromechanical systems (MEMS) silicon chip developed by researchers from the Agency for Science, Technology and Research (A*STAR)Institute of Microelectronics, Singapore, in collaboration with colleagues from the National University of Singapore, can rotate scanning laser beams by almost a full turn at high speed.
Their small size makes MEMS devices ideal for circumferential diagnostic imaging systems. Their small scanning angles, however, limited earlier attempts to fabricate such devices. The difficulty arose from the inability to fully utilize standard MEMS-based actuators and their linear movements for rotational devices.
An important advance in the A*STAR device's design is the implementation of a new reflector for the scanning laser. The team designed a pyramidal polygon reflector as the key component to realize full circumferential scanning. This reflector is placed on a structure that translates the linear movement of the electrostatic actuators into the large rotational motion of the reflector.
Four electrostatic actuators on the side of the device rotate the pyramid, which is mounted on a ring, by about 40 degrees. Since there are eight facets of the pyramid, this means that nearly the full circumferential area is covered by the laser illuminating the pyramid.
Because the actuators only use electrical fields to create movement via electrostatic repulsion, almost no electrical current is used. As such, the device consumes very little power and generates no heat, which makes it compatible for medical applications inside the body.
