Operation Under Unusual Conditions

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

spinner.

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:

(1) Check for completeness and general condition of the

equipment.

(2) Clean the equipment with the lint-free cloth. Remove dust,

foreign matter, and moisture from all parts before and after

use.

(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

properly.

49.4. Functioning of Spinner

a. General.

(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

between

two

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

pattern.

(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

TAGO 763B