Abstract

Speckle in rear-projection screens, such as those used in microfiche viewers, reduces resolution and can cause viewer fatigue. Many speckle-reduction techniques have been tried with varying degrees of success, including rapid movement of a single screen in its plane, the use of two stationary spaced screens, liquid-crystal screens, and the use of two closely spaced screens in slow relative orbital motion. We describe a simplified, two-screen support that permits only linear screen motion, and show that such motion provides total speckle elimination. An analysis of speckle in such screens is presented which accounts for the observed remarkable sensitivity of the speckle pattern to minute screen displacements. To confirm this analysis we have measured the speckle pattern’s correlation as a function of screen displacement using the speckle interferometry method of Françon. We consider the effects of a spatially and spectrally extended incandescent light source, and conclude that these effects are negligible in our application compared to the effect of screen motion. We show that these three speckle-reducing effects (screen motion, spatial extent of the source, and spectral extent of the source) can be considered together by introducing the notion of space-time correlation cells.

© 1976 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. N. H. Mason, British Patent No. 590, 981 (1947).
  2. C. E. Hauber and R. E. Kittredge, U. S. Patent No. 3, 473, 862 (Oct.21, 1969).
  3. D. B. Huber, U. S. Patent No. 3, 705, 757 (Dec.12, 1972).
  4. N. George and A. Jain, Opt. Commun. 15, 71–75 (1975).
    [Crossref]
  5. C. E. Baker, U. S. Patent No. 3, 650, 608 (March21, 1972).
  6. J. V. Cartmell and D. Churchill, U. S. Patent No. 3, 674, 338 (July4, 1972).
  7. F. S. MacAdam and TaylorTaylor & Hobson Ltd., British Patent No. 592, 815, (1947).
  8. I. Leifer, C. J. D. Spencer, W. T. Welford, and C. N. Richmond, J. Opt. Soc. Am. 51, 1422–1423 (1961).
    [Crossref]
  9. R. R. Firth, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).
  10. R. N. Wolfe, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).
  11. E. G. Rawson and R. E. Norton, J. Opt. Soc. Am. 64, 1401 (abstract) (1974).
  12. N. George and A. Jain, Appl. Opt. 12, 1202–1212 (1973).
    [Crossref] [PubMed]
  13. Xerox University Microfilms, Ann Arbor, Mich.
  14. Polacoat is a division of the 3M Co., 3M Center, St. Paul, Minn.
  15. Allied Chemical, Specialty Chemicals Div., Morristown, N. J. 07960.
  16. J. Dyson, J. Opt. Soc. Am. 50, 519–520 (1960).
    [Crossref]
  17. M. Born and E. Wolf, Principles of Optics, 4th ed. (Pergamon, New York, 1970), p. 521.
  18. M. Françon, Opt. Acta 20,(1973).
    [Crossref]

1975 (1)

N. George and A. Jain, Opt. Commun. 15, 71–75 (1975).
[Crossref]

1974 (1)

E. G. Rawson and R. E. Norton, J. Opt. Soc. Am. 64, 1401 (abstract) (1974).

1973 (2)

1961 (1)

1960 (1)

Baker, C. E.

C. E. Baker, U. S. Patent No. 3, 650, 608 (March21, 1972).

Born, M.

M. Born and E. Wolf, Principles of Optics, 4th ed. (Pergamon, New York, 1970), p. 521.

Cartmell, J. V.

J. V. Cartmell and D. Churchill, U. S. Patent No. 3, 674, 338 (July4, 1972).

Churchill, D.

J. V. Cartmell and D. Churchill, U. S. Patent No. 3, 674, 338 (July4, 1972).

Dyson, J.

Firth, R. R.

R. R. Firth, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).

Françon, M.

M. Françon, Opt. Acta 20,(1973).
[Crossref]

George, N.

Hauber, C. E.

C. E. Hauber and R. E. Kittredge, U. S. Patent No. 3, 473, 862 (Oct.21, 1969).

Huber, D. B.

D. B. Huber, U. S. Patent No. 3, 705, 757 (Dec.12, 1972).

Jain, A.

Kittredge, R. E.

C. E. Hauber and R. E. Kittredge, U. S. Patent No. 3, 473, 862 (Oct.21, 1969).

Leifer, I.

MacAdam, F. S.

F. S. MacAdam and TaylorTaylor & Hobson Ltd., British Patent No. 592, 815, (1947).

Mason, N. H.

N. H. Mason, British Patent No. 590, 981 (1947).

Norton, R. E.

E. G. Rawson and R. E. Norton, J. Opt. Soc. Am. 64, 1401 (abstract) (1974).

Rawson, E. G.

E. G. Rawson and R. E. Norton, J. Opt. Soc. Am. 64, 1401 (abstract) (1974).

Richmond, C. N.

Spencer, C. J. D.

Taylor,

F. S. MacAdam and TaylorTaylor & Hobson Ltd., British Patent No. 592, 815, (1947).

Welford, W. T.

Wolf, E.

M. Born and E. Wolf, Principles of Optics, 4th ed. (Pergamon, New York, 1970), p. 521.

Wolfe, R. N.

R. N. Wolfe, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).

Appl. Opt. (1)

J. Opt. Soc. Am. (3)

Opt. Acta (1)

M. Françon, Opt. Acta 20,(1973).
[Crossref]

Opt. Commun. (1)

N. George and A. Jain, Opt. Commun. 15, 71–75 (1975).
[Crossref]

Other (12)

C. E. Baker, U. S. Patent No. 3, 650, 608 (March21, 1972).

J. V. Cartmell and D. Churchill, U. S. Patent No. 3, 674, 338 (July4, 1972).

F. S. MacAdam and TaylorTaylor & Hobson Ltd., British Patent No. 592, 815, (1947).

R. R. Firth, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).

R. N. Wolfe, U. S. Patent No. 3, 640, 602 (Feb.8, 1972).

N. H. Mason, British Patent No. 590, 981 (1947).

C. E. Hauber and R. E. Kittredge, U. S. Patent No. 3, 473, 862 (Oct.21, 1969).

D. B. Huber, U. S. Patent No. 3, 705, 757 (Dec.12, 1972).

M. Born and E. Wolf, Principles of Optics, 4th ed. (Pergamon, New York, 1970), p. 521.

Xerox University Microfilms, Ann Arbor, Mich.

Polacoat is a division of the 3M Co., 3M Center, St. Paul, Minn.

Allied Chemical, Specialty Chemicals Div., Morristown, N. J. 07960.

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (9)

FIG. 1
FIG. 1

Schematic drawing of the tandem screen assembly.

FIG. 2
FIG. 2

Images projected on a microfiche viewer showing speckle on (a) an unmodified screen, (b) two stationary screens in contact, and (c) two screens in slow relative motion separated by ~ 0.25 mm.

FIG. 3
FIG. 3

Effect of separating two stationary screens. Screen separation is (a) 0.1 mm, (b) 0.75 mm, and (c) 2.0 mm.

FIG. 4
FIG. 4

Illustration of the effect of screen motion; (a) definition of parameters and (b) the region about a point on the surface of diffuser D2.

FIG. 5
FIG. 5

Measurement of speckle pattern correlation as a function of screen displacement; (a) recording and (b) measurement.

FIG. 6
FIG. 6

Far-field photographs recorded in the plane of the scanner indicated in Fig. 5(b); the horizontal shift of the film between exposures is (a) 0.0 μm, (b) 10.0 μm, and (c) 25 μm.

FIG. 7
FIG. 7

Measured fringe visibility as a function of screen shift. The solid line is a smooth line of best fit.

FIG. 8
FIG. 8

Illustration of (a) the effect of an extended source width and (b) the area ratio of ΔSe to ΔS2.

FIG. 9
FIG. 9

Illustration of the effect of an extended spectral bandwidth.

Equations (6)

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

Δ S 1 = λ / sin ( 1 2 Θ 1 ) .
N s = ( Δ S e Δ S 2 ) 2 = ( λ / sin ( 1 2 Θ e ) λ / sin ( 1 2 Θ s ) + d tan Θ 1 ) 2 .
N t = δ ( λ ¯ ) 2 / Δ λ ,
δ = { D p 2 + [ d tan ( 1 2 Θ 1 ) ] } 1 / 2 - D p + d cos ( 1 2 Θ 1 ) - d d 2 tan 2 ( 1 2 Θ 1 ) 2 D p + d ( 1 - cos ( 1 2 Θ 1 ) cos ( 1 2 Θ 1 ) ) .
N t = d 2 Δ λ tan 2 ( 1 2 Θ 1 ) 2 ( λ ¯ ) 2 D p + d Δ λ ( λ ¯ ) 2 ( 1 - cos ( 1 2 Θ 1 ) cos ( 1 2 Θ 1 ) ) .
σ I / I = N t N s N m - 1 / 2 .