An X-ray localizer light system comprises: a long life X-ray localizer light
source;
an optical concentrator, the light source being situated at a first focal spot,
the optical concentrator being configured for concentrating X-ray localizer light
from the light source to a second focal spot; and an opaque shield having an aperture
therein situated proximate to the second focal spot and being of such a geometrical
shape so as to maximize light throughput while meeting light field edge contrast
requirements. In another light system, the optical concentrator comprises a reflector
comprising a quasi-ellipsoidal portion within which the light source is situated,
a cylindrical portion situated between the quasi-ellipsoidal portion and the shield
for reflecting stray light, a back reflector portion situated proximate to the
shield, and a centrally-mounted portion situated between the aperture and the light
source for directing back-reflected light in the direction of the aperture.
