Simple telecentric submillimeter lens with near-diffraction-limited performance across an 80 degree field of view.

A simple and compact telecentric lens based on two hemispheric optical elements arranged in a formation resembling an "hourglass" is proposed and evaluated. Our modeling and experimental results show the ability of this lens in achieving high resolution over a large field of view. A prototype with 500 μm total thickness is built using silicon micromachining methods for a center wavelength of 1500 nm. Experimental measurement shows near-diffraction-limited performance and good telecentricity over an 80° field of view at a numerical aperture of 0.2. All elements of the hourglass lens are in direct contact, and hence the alignment is extremely simple. We believe the proposed lens is a good candidate for compact and low-cost multi-aperture imagers.