49.2. Operation Under Unusual Conditions
The instructions for operation of the projector in artic areas (para.
32) and in tropic and desert areas (para. 34) are applicable to the
49.3. Operator's and Organizational Maintenance
a. The materials required for maintenance of the spinner are the
same as those listed (para.. 36) for the projector.
b. Perform the following preventive maintenance procedures daily:
(2) Clean the equipment with the lint-free cloth. Remove dust,
foreign matter, and moisture from all parts before and after
(3) Inspect the equipment for evidences of mildew and fungi.
(4) Check to see that the power cable plug is properly secured.
(5) Apply power and check to see that equipment is operating
49.4. Functioning of Spinner
(1) Ordinarily (unpolarized) light. waves vibrate in all planes
about the direction of light propagation. When these waves
are directed through a single polarized only vibrations of a
certain plane will pass through. This is simple polarization,
and it produces no apparent change in the light.
(2) When light is passed through two sheets of polarizing ma-
terial, each sheet of which polarizes the light in a different
plane, intereference patterns are produced. These are dif-
fraction patterns, and they appear either as parallel lines of
alternating light and dark shades or as contrasting colors.
The parallel lines are straight, circular, or elliptical depend-
ing on the nature of the actual polarizing material. When
one polarizing material is rotated relative to the other, the
lines of polarized light appear to move.
b. Optical System. The optical system of the spinner consists of a
polarized sheet which, for protect, is sandwiched
identical round pieces of glass. The polarization pattern is uniform
and light planes at any reference point remain constant.
(1) The portion of the overall patter, design, or illustration to
be animated is made of polarized transparency: the light
emerging from that portion of the overall transparency
mounted on the projector is polarized in a corresponding
(2) All of the light passes through the rotating polarizer to the
projection lens (fig. 2). The Iight which passes through the
unpolarized portion of the transparency projects a normal,
fixed image upon the screen. The single plane of the polar-
ized light, however, intersects continuously, at angles varying