Department of Mechanical Engineering
Kenneth E. Goodson
High spatial resolution thermometry is important for a variety of applications including electronic circuits, biological and chemical microsystems and advanced photonic devices including lasers and radar. Infrared imaging is one of the most common thermometry methods for macroscale systems, but application to microstructures is limited in spatial resolution by diffraction to approximately 3-5 microns.
This work extended previous work on solid immersion lens technology to infrared wavelength by means of silicon microcantilever lenses. The fabrication process for the lens involves patterning of a resist micropillar and reflow into a curved lens shape through exposure to acetone vapor followed by reactive ion etching into a silicon on insulator substrate. Early progress with these lenses demonstrated the resolution improvement to be primarily due to the higher refractive index of infrared light in silicon (approximately 4.0), which allows spatial substantially higher spatial resolution with relatively modest reduction in signal intensity. The lens was ultimately used for imaging of thermal signals and distinguished feathers below one micrometer.