Как освещали сцену на съемках лунной аферы

In a sun system, it is desirable to provide
means for varying the intensity of illumination over a
relatively wide range without change in the spectral dis-
tribution of the illumination, so that the simulator may
be used to simulate not only sunlight, but also earthlight
and moonlight. In order to provide sufficient illumination
to simulate sunlight over a practicably large area, it is
necessary to employ plural light sources, and it is desirable
to control the intensity of illumination by varying the
number of the light sources that are energized, thereby
avoiding changes in the spectral distribution of the light
output of the simulator, and maintaining a relatively high
degree of eficiency. It is also desirable to avoid localized
field darkening effects caused by the selective extinguish-
ment of the individual light sources, and to maintain uni-
formity of illumination over the entire field toward which
the illuminator is directed.

Accordingly, one important object of the present inven-
tion is to provide a novel illumination system including
means for combining the outputs of plural light sources
to form a single virtual source, the intensity of which varies
in accoidance with the number of individual real sources
that are selectively energized at any one time.

Other objects are: to provide a novel illumination sys
tem particularly suitable for use as a sun simulator in
conjunction with an environmental test chamber; to pro
vide a novel illumination system of this type in which
the real light sources may be positioned exteriorly of the
test chamber and their light outputs directed into the tes
chamber through a relatively small window; to provide a
novel illumination system of this type including means
for producing a virtual source within the chamber, the
intensity of which is proportional to the total number of
the real sources that are energized at any given time;
and in general, to provide an illumination system of this
type which is of relatively simple and rugged construc-
tion, and reliable and convenient in operation.