CW4C.2.pdf Imaging and Applied Optics © OSA 2013 Fiber-coupled monocentric lens imaging Joseph E. Ford, Igor Stamenov, Stephen Olivas , Glenn Schuster, Nojan Motamedi, and Ilya P. Agurok UCSD Electrical and Computer Engineering, 9500 Gilman Drive, La Jolla, California 92093-0409 Ron A. Stack, Adam Johnson, and Rick Morrison Distant Focus Corporation, 4114B Fieldstone Road, Champaign, IL 61822 Abstract: Monocentric lenses have proven exceptionally capable of high numerical aperture wide-field imaging - provided the overall system can accommodate a spherically curved image surface. We will present a summary of recent work on the design optimization and experimental demonstrations of monocentric wide-field imaging, including systems based on waveguide coupling of the image to conventional focal plane sensor(s). OCIS codes: (080.3630) Lenses; (110.0110) Imaging systems; (220.3620) Lens system design. Conventional "fisheye" imagers map wide fields of view onto flat image sensors, but suppressing field curvature imposes harsh design tradeoffs, especially as the focal length grows. Monocentric lenses are the polar opposite. The symmetry in a lens made of concentric hemispherical surfaces cancels most of the geometrical aberrations, and enables high-resolution image formation on a hemispherical image surface [1-2]. Figure 1 shows three designs for a 120˚ field of view and 12 mm focal length lens. At top is a F/2 retro-telephoto lens with good resolution, but substantial bulk. The center design shows a related "compact" design which sacrifices both resolution and light collection. The monocentric achromatic lens below is smaller, simpler, and provides much higher resolution on the spherical image surface. The apparent reduction in aperture area is misleading. Most of the light incident on the larger lenses is blocked by the internal aperture, whereas the smaller lens transmits a uniform fraction of the light, resulting in a lower F/# at all angles. The graph inset at lower left is a familiar bubble-chart of the field of view and light collection for standard flat-field objective lenses [3]. Monocentric lenses open a previously unachievable domain, but the question remains how the image can be recorded, and the stray light blocked, for a spherical image surface. One way is to relay-image overlapping areas of the sphere to planar sensors, using aperture stops in each relay to control stray light, and image processing to fuse the overlapping image boundaries [4-6]. This enables multi- Gigapixel real-time imaging, but the relay optics (e.g., 221 sets for a 2.5Gpix imager) add significant complexity and cost. Here we describe an alternative, using high-resolution fiber bundles for image transfer to planar sensors. !" $$ !$$ %$$ !"#$%& ( )*+$ ,-./0 ! 46 78//' 98:80 46 !;! *2< 46 !;&! *2< ()*+,+- )/ 012 345 !'! !'% !'" !'& !'# $'! ! "! #! $%! $&! %!! !"#$%%& 46 !;=! *2< ! "## $%&## &## '()*+, . /0* 12/%3 ()*+,+- )/ 012 345 !'! !'% !'" !'& !'# $'! ! "! #! $%! $&! %!! !"#$%%& 46 78//' 98:80 46 !;! *2< 46 !;&! *2< 46 !;=! *2< ! "! #! $%! $&! %!! !"#$%%& !'! !'% !'" !'& !'# $'! ()*+,+- )/ 012 345 46 78//' 98:80 46 !;! *2< 46 !;&! *2< 46 !;=! *2< &'()*+ , -.) /0-1% -2. $$ .2 $$ Fig. 1: Comparison of three large numerical aperture 12 mm focal length lenses with a 120˚ field of view, showing the increase in resolution possible with monocentric lenses and a spherical image surface.