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.
We demonstrate subwavelength spatial resolution with a scanning microlens operating in collection mode with a large-area detector. Optical contrast is created by refraction of off-axis light rays at angles larger than the maximum collection angle. With a microfabricated silicon microlens 10 microns in diameter, we measure spatial resolution due to refraction contrast of lambda/4.3 at a wavelength of 10.7 microns. A model based on ray tracing is developed to explain our result, and we show that lens diameter and index of refraction limit resolution for large emission and collection angles.