Infrared Solid Immersion Lens

Sponsors: 
NSF, DOE
Collaborators: 
Quate and Kino groups (Stanford EE / Applied Physics)

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.

PROJECT PUBLICATIONS

Fletcher, D.A., Kino, D.S., and Goodson, K.E., 2003, "Thermal Microscopy with a Microfabricated Solid Immersion Lens," Microscale Thermophysical Engineering, Vol. 7, pp. 267-273.

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Cahill, D., Goodson, K.E., and Majumdar, A., 2002, "Thermometry and Thermal Transport in Micro/Nanoscale Solid-State Devices and Structures," ASME Journal of Heat Transfer, Vol. 124, pp. 223-240.

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Fletcher, D.A., Crozier, K.B., Quate, C.F., Kino, G.S., Goodson, K.E., Simanovskii, D., Palanker, D.V., 2001, "Refraction Contrast Imaging with a Scanning Microlens," Applied Physics Letters, Vol. 78, pp. 3589-3591.

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Fletcher, D.A., Crozier, K.B., Guarini, K.W., Minne, S.C., Kino, G.S., Quate, C.F., and Goodson, K.E., 2001, "Microfabricated Silicon Solid Immersion Lens," IEEE/ASME Journal of MicroElectroMechanical Engineering, Vol. 10, pp. 450-459.

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Fletcher, D.A., Goodson, K.E., and Kino, G.S., 2001, "Focussing in Microlenses Close to a Wavelength in Diameter," Optics Letters, Vol. 26, pp. 399-401.

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Fletcher, D.A., Crozier, K.B., Quate, C.F., Kino, K.S., Goodson, K.E., Simanovskii, D., and Palanker, D.V., 2000, "Near-Field Infrared Imaging with a Microfabricated Solid Immersion Lens," Applied Physics Letters, Vol. 77, pp. 2109-2111.

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Goodson, K.E., and Asheghi, M., 1997, "Near-Field Optical Thermometry," Microscale Thermophysical Engineering, Vol. 1, pp. 225-235.

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