Plane Wave Imager

 A Plane Wave Imager (PWI) replaces the lens with an array of evanescent couplers. PWI forms an image using the same light characteristics as a lens.  

In the illustration at the bottom, the PWI is covered with a protective plate. The green board under the PWI is display interface electronics and user controls.

Here, a PWI is combined with a Waveguide Display to create a high power but very small telescope. The illustration shows birds at night being observed with a Short Wave Infrared, PWI imager.

Each PWI is small (about a square inch perhaps) in order to keep CMOS producibility high and cost low. An array of PWI creates a large optical aperture without needing to maintain precise alignment of the several different PWI. 

At the bottom, several PWI can either provide a wide field of view or enhanced resolution of a narrow field of view.

 On the home page, four PWI are folded into a compact box. When unfolded, the optical aperture is about 4 square inches. The four PWI need not be precisely aligned. 

Incoherent light interferes with itself, forming a co-sinusoidal intensity variation as the time delay between light streams varies. The phase variation across an array of light couplers depends on the angle of arrival of the light wave. Many light waves hit the PWI, and a Fourier Transform of the signal from many couplers forms the image.

This figure is a simplified layout of a PWI pixel. The delay between arms of the evanescent coupler is varied so that the light streams go from a delay greater than coherence length, through peak, and out of phase again. Mean signal variation is digitized and transformed to get the image.