Abstract

Variable contrast in the image of non-uniform objects is obtained by polarizing orthogonally the deviated and undeviated bundles of light due to diffraction by the object. Advantage is taken of this orthogonality of polarization to effect variable phase difference between, and variable amplitude ratio of the deviated and undeviated bundles. These modified, interfering bundles produce the image and permit continuously variable contrast.

Of many possible polanret systems two are described. In the preferred system, the phase difference between the deviated and undeviated bundles is varied throughout one wave-length by rotation of the polarizer, and the amplitude ratio is varied practically in all proportions by rotation of the analyzer. The light is plane polarized either before or after passage through the object, passes through a uniform quarter-wave plate, through the zonal polarizer, and finally through the analyzer. The zonal polarizer consists of two thin, adjoining, plane-polarizing elements oriented at right angles. One element covers the image of the condenser diaphragm as formed by the intervening lenses of the condenser and objective, the other, the remaining area of the clear aperture. The principal axes of the quarter-wave plate bisect the transmission directions of the zonal polarizer.

Wide range in contrast has been obtained with experimental polanret systems with microscope objectives of long focal length.

© 1947 Optical Society of America

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References

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  1. H. Osterberg, J. Opt. Soc. Am. 36, 473–474 (1946).
    [CrossRef]
  2. Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
    [CrossRef]
  3. H. Osterberg, J. Opt. Soc. Am. 36, 474 (1946).
    [CrossRef]
  4. H. Osterberg, J. Opt. Soc. Am. 36, 475–476 (1946).
    [CrossRef]
  5. Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
    [CrossRef]

1946 (5)

H. Osterberg, J. Opt. Soc. Am. 36, 473–474 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 474 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 475–476 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Bennett,

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Jupnik,

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

Osterberg,

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Osterberg, H.

H. Osterberg, J. Opt. Soc. Am. 36, 474 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 475–476 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 473–474 (1946).
[CrossRef]

Richards,

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

J. Opt. Soc. Am. (3)

H. Osterberg, J. Opt. Soc. Am. 36, 473–474 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 474 (1946).
[CrossRef]

H. Osterberg, J. Opt. Soc. Am. 36, 475–476 (1946).
[CrossRef]

Trans. Am. Micro. Soc. (2)

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 124–125 (1946).
[CrossRef]

Bennett, Jupnik, Osterberg, and Richards, Trans. Am. Micro. Soc. 65, 105–106 (1946).
[CrossRef]

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Figures (4)

F. 1
F. 1

Optical system of the phase microscope. The microscope lamp, which is not shown, is focused for Kohler illumination.

F. 2
F. 2

A direct polanret system. C is the substage condenser; S, the object slide; O, the objective; G are glass plates which are cemented to the orthogonal zonal polarizers. The variable retarding plate may be a Berek or a uniform field Babinet compensator. Analyzer and polarizer are rotatable.

F. 3
F. 3

The essential elements and parameters of a preferred polanret system. A and P are the transmission directions of the uniform analyzer and polarizer, E1 and E2, of the zonal polarizers which cover the conjugate and complementary areas, respectively. X is the direction of vibration of the slow ray in the quarter-wave plate and is selected as the direction of reference. The zonal polarizers and quarter-wave plate are fixed; the analyzer and polarizer, rotatable. The indicated θ-direction is positive, namely, that in which rotation of the polarizer increases the optical path of the conjugate area with respect to that of the complementary area.

F. 4
F. 4

The optical system of a preferred polanret system. The microscope lamp is not shown. In the experimental system the quarter-wave plate and zonal polarizers were cemented to one another and between glass plates.

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

T = r 2 .
d = 2 θ 360 = θ 180 wave lengths .
T = r 2 = tan 2 α ,