Wide field of view optical element having plural reflectors of different widths
 A wide field-of-view optical element 12 suitable for use in a laser warning system including a frusto-conical block of optically transparent material having a first surface 14 and a second surface 16. The first surface 14 is parallel with the second surface 16 and coaxial therewith. The radius R.sub.1 of the first surface 14 is less than the radius R.sub.2 of the second surface such that the sides of the element 12 are slanted. Reflective material is coated on the interior 17 of the first surface 14 for directing incident optical energy toward a detector 20 mounted at the second surface 16. Similarly, a reflective material is coated on the interior 18 of the second surface 16 for directing incident optical energy to the detector 20 via the first surface 14. The second reflective coating on the second surface is disposed between the outer periphery thereof and a nonzero distance R.sub.3 from the center thereof to provide an aperture at which the detector 20 may be mounted. 
Santa Barbara Research Center
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Alan W.
Holmes