Abstract

A study has been made of the resolving power of the human eye for Foucault test objects of different inherent contrast viewed through circular artificial pupil stops ranging from 0.30 of a millimeter to 7.0 millimeters in diameter. Two methods were used to make the resolution measurements. The first consisted of viewing the test objects through circular apertures in 10-mil blackened brass shim stock disks placed about 3 millimeters from the observer’s eye. Provision was made for illuminating the test objects both with tungsten lamps and with mercury arcs. The second method involved the use of test objects viewed in collimated light by means of a telescopic system for which the exit pupil could be varied from 0.40 of a millimeter to 2.0 millimeters. Both methods used equipment embodying the basic principles of the K.D.C. apparatus. The study included resolution measurements for rectangular and square Foucault test objects consisting of straight parallel black and white bands having an inherent contrast of approximately 94 percent. The coefficient of specific resolution was computed for test objects having lower values of inherent contrast. The resolution measurements, totaling over 100,000, were made by thirty-two different observers ranging from 18 to 76 years in age. The coefficient of specific resolution was found to be practically independent of age and observer for artificial pupil stops less than 0.75 of a millimeter in diameter. This suggests an effective consistency of the contrast threshold of the human retina as far as resolution measurements are concerned and indicates that the diffraction of light at the pupil stop is the primary factor controlling resolution. For artificial pupil stops of larger diameter, the coefficient of specific resolution was found to depend upon the individual observer but only with a maximum variation among the observers used of 30 percent. The composition of the test object was found to influence the coefficient of specific resolution to a certain extent with an indication that the best resolution was obtainable with test objects having the greatest number of elements.

© 1949 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. H. S. Coleman and S. W. Harding, J. Opt. Soc. Am. 37, 263 (1947)
    [Crossref] [PubMed]
  2. H. S. Coleman and M. F. Coleman, J. Opt. Soc Am. 37, 572 (1947).
    [Crossref] [PubMed]

1947 (2)

Coleman, H. S.

Coleman, M. F.

H. S. Coleman and M. F. Coleman, J. Opt. Soc Am. 37, 572 (1947).
[Crossref] [PubMed]

Harding, S. W.

J. Opt. Soc Am. (1)

H. S. Coleman and M. F. Coleman, J. Opt. Soc Am. 37, 572 (1947).
[Crossref] [PubMed]

J. Opt. Soc. Am. (1)

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 (11)

F. 1
F. 1

Schematic diagram of the pupil stop apparatus.

F. 2
F. 2

The pupil stop apparatus.

F. 3
F. 3

Schematic diagram of the K.D.C. apparatus Model 7 used to measure the resolving power of the human eye.

F. 4
F. 4

Form of Foucault test objects used in the pupil stop apparatus.

F. 5
F. 5

The minimum angle of resolution for the human eye vs. the diameter of the pupil stop used in the pupil stop apparatus.

F. 6
F. 6

The minimum angle of resolution of the human eye vs. pupil stop diameter obtained using the K.D.C. apparatus Model 7.

F. 7
F. 7

The minimum angle of resolution vs. the reciprocal of the diameter of the artificial pupil stop for the human eye.

F. 8
F. 8

The coefficient of specific resolution vs. inherent contrast of Foucault test objects viewed through artificial pupil stops of various sizes.

F. 9
F. 9

The minimum angle of resolution vs. the artificial pupil stop diameter for Foucault test objects in the form of different size squares.

F. 10
F. 10

The minimum angle of resolution vs. the artificial pupil stop diameter for Foucault test objects of different composition.

F. 11
F. 11

The minimum angle of resolution vs. artificial pupil stop diameter for Foucault test objects illuminated with green mercury light.

Tables (10)

Tables Icon

Table I Minimum angle of resolution for a Foucault test object of a 94 percent inherent contrast vs. the diameter of an artificial pupil stop placed 3 mm from the pupil of the human eye.

Tables Icon

Table II Minimum angle of resolution of a Foucault test object of 94 percent inherent contrast as a function of the exit pupil of a high grade telescopic system.

Tables Icon

Table III The coefficient of specific resolution for a Foucault test object of 94 percent inherent contrast vs. age of the observer.

Tables Icon

Table IV Computed values of the coefficient of specific resolution of Focault test objects of different inherent contrast viewed through an artificial pupil stop 0.4 of a mm in diameter.

Tables Icon

Table V Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 0.6 of a mm in diameter.

Tables Icon

Table VI Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 0.7 of a mm in diameter.

Tables Icon

Table VII Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 0.8 of a mm in diameter.

Tables Icon

Table VIII Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 1.0 mm in diameter.

Tables Icon

Table IX Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 1.5 mm in diameter.

Tables Icon

Table X Computed values of the coefficient of specific resolution of Foucault test objects of different inherent contrast viewed through an artificial pupil stop 2.0 mm in diameter.

Equations (7)

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

R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )
R ¯ ( mm-rad. × 10 5 )