An optical element is provided that may be used for collecting optical
radiation incident at large angles of incidence. The element may include
a grating window formed of grating elements that may collect large
incident angle radiation and reflect that radiation, e.g., under total
internal reflection in a substantially normal direction. A lens or lens
array may be used to collect the internally reflected radiation and focus
that radiation to a detector. Example detectors include infrared
detectors. The element may be formed to collect, reflect, and redirect
optical radiation incident at angles above 45.degree. as measured from a
surface normal to a detector oriented substantially at normal incidence.
The detected signal from the optical element may be used to control
systems within an aircraft or other vehicle capable of flight. In another
application, the optical element may also be used to project optical
radiation at the same large angles by replacing the detector elements
with light sources, such as light emitting diodes.