Optical: systems and elements – Lens – Reverse telephoto
Reexamination Certificate
1999-10-07
2001-11-20
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
Reverse telephoto
C359S796000, C250S207000, C250S2140VT
Reexamination Certificate
active
06320703
ABSTRACT:
BACKGROUND
The present invention relates generally to electro-optical sensor systems, and more particularly, to ultra-wide field of view concentric electro-optical sensor systems.
Most currently used sensor architectures employ a multiple field of view optical system with a focal surface array located at an image plane to receive radiation from an image scene. A high resolution narrow field of view telescope performs tracking and identification functions. For searching and acquisition mode, a wide field of view attachment is flipped into the narrow field of view telescope to increase the field of view coverage. The sensor is mounted on a gimbal system to cover the entire field of regard. Unfortunately, such systems are relatively bulky and complex because of the moving mechanisms used therein, and which generally has a very tight tolerance margin and is potential source of failure.
Accordingly, it is an objective of the present invention to provide for ultra-wide field of view concentric electro-optical sensor systems that improve upon conventional systems.
SUMMARY OF THE INVENTION
The drawbacks associated with prior art systems may be overcome by a sensor constructed in accordance with the principles of the present invention, and which is a very compact, high numerical aperture, high resolution, ultra-wide field of view (FOV) concentric optical sensor. The concentric optical sensor comprises a concentric lens having an aperture stop at its center, and a curved focal surface array concentrically disposed around a portion of the concentric lens centered upon the center of the aperture stop.
The present invention also provides for a concentric refractive lens system having a concentric air lens that serves as a cold stop. The optical elements following the concentric air lens are enclosed inside a dewar containing the focal surface array. The present invention also provides for an image intensifier employing a concentric lens as an objective lens to achieve low F-number and wide field of view coverage.
The concentric lens provides very high image quality for f-numbers faster than 1.0 and a field of view coverage of up to 180 degrees. The overall size of the sensor is about two times its effective focal length EFL). Compared to a fisheye lens that provides for a 120 degrees field of view, the size of the overall fisheye lens is at least 6 times its effective focal length. The total volume of the fisheye lens is at least 20 times that of the comparable concentric lens used in the present sensor. Additionally, the f-number of a fisheye lens is at least two times slower than that of the concentric lens used in the present sensor.
The focal surface array may be a curved and concentric with respect to the center of the concentric lens. The focal plane array may be coplanar with detector elements distributed along a ring centered around the optical axis of the sensor. The focal plane array may include multiple stripes concentric with respect to the center of the concentric lens.
REFERENCES:
patent: 4184749 (1980-01-01), Grossman
patent: 4679912 (1987-07-01), Loy
patent: 5004328 (1991-04-01), Suzuki et al.
patent: 5311611 (1994-05-01), Migliaccio
patent: 6097545 (2000-08-01), Vaughan
patent: 6233100 (2001-05-01), Chen et al.
Anderson J. Steve
Chen Chungte W.
Alkov Leonard A.
Epps Georgia
Lenzen, Jr. Glenn H.
Raufer Colin M.
Raytheon Company
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