REMOTE OPTICAL-DETECTION USING MICROCANTILEVERS

The feasibility of microcantilever-based optical detection is demonstr ated. Microcantilevers may provide a simple means for developing singl e-element and multielement infrared sensors that are smaller, more sen sitive, and lower in cost than quantum well, thermoelectric, or bolome tric sensors. Here we specifically report here on an evaluation of lab oratory prototypes that are based on commercially available microcanti levers, such as those used in atomic force microscopy. In this work, o ptical transduction techniques were used to measure microcantilever re sponse to remote sources of thermal energy. The noise equivalent power at 20 Hz for room temperature microcantilevers was found to be approx imately 3.5 nW/root Hz, with a specific detectivity of 3.6x10(7) cm Hz (1/2)/W, when an uncoated microcantilever was irradiated by a low-powe r diode laser operating at 786 nm. Operation is shown to be possible f rom de to kHz frequencies, and the effect of cantilever shape and the role of absorptive coatings are discussed. Finally, spectral response in the midinfrared is evaluated using both coated and uncoated microca ntilevers. (C) 1996 American Institute of Physics.