As
the dove prism is rotated about its own long axis, the
orientation of its image rotates at twice the angular
displacement. Thus, an image can be rotated through
180¡ã by rotating the dove prism through only 90¡ã .
Nevertheless,
the dove prism is simply one section of a right-angle
prism
A
collimated beam of light directed into the prism through
one inclined face will be refracted toward the base,
where total internal reflection inverts the beam and
directs it out through the second inclined face
Because
the two inclined faces are symmetrically angled with
respect to the base, the output beam travels the same
trajectory as the input beam; there is no deviation
or displacement of the beam.
Engineers
use dove prisms to invert an image or to provide continuous
control of the orientation of an inverted image. Limitations
are related to its size (it must be rather long compared
to its aperture) and to its aberrational effects upon
beams that are converging or diverging. Collimated beams
are preferred because they do not experience aberration
as they pass through the prism.
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