The four-reflection camera achieves a field of view of 17° over 1.92 Mpixels of a color image sensor with 3 µm pixels in just 5.5 mm of total track. With its less extreme focal length (19 mm) and smaller obscuration (0.8), this concentric multi-reflection (CMR) lens design has a wider field of view, better sensitivity, smaller volume and broader depth of field than the previously demonstrated eight-reflection camera prototype.
This four-reflection camera also incorporates an extremely sensitive method of refocus utilizing the sensitivity of the concentric aspheric mirror separations. A spacing adjustment of only 15 microns is sufficient to focus the camera from 4m to infinity.
(Below) Four-Reflection lens schematic and MTF
(Left) Four-Reflection camera assembly
(Below) Assembled Four-Reflection camera prototype.
(Below) Four-Reflection camera performance at 4m
(Below) Outdoor images taken with the Four-Reflection camera
For more information:
E. Tremblay, R. Stack, R. Morrison, J. Karp, and J. Ford, "Ultrathin four-reflection imager," Appl. Opt. 48, 343-354 (2009).