Abstract

Either of two problems in calibrating Maxwellian-view optical systems can arise when troland value is calculated from measurements made by photometers requiring a visual match. Both problems lead to inaccurate estimates of light levels produced by the optical system.

© 1982 Optical Society of America

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References

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  1. G. Wyszecki and W. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulas (Wiley, New York, 1967), pp. 212–214.
  2. D. A. Palmer, “Mesopic photometry with nonmonochromatic lights,” J. Opt. Soc. Am. 64, 1386 (1974); “Standard observer for large-field photometry at any level,” J. Opt. Soc. Am. 58, 1296–1299 (1968); “The definition of a standard observer for mesopic photometry,” Vision Res. 7, 619–628 (1967).
    [PubMed]
  3. G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
    [Crossref] [PubMed]
  4. D. B. Judd, “Report of U.S. Secretariat Committee on Colorimetry and Artificial Daylight,” CIE Proc.I(7), 11 (1951).
  5. There is an additional problem caused by changes of focus of the objective of the SEI meter with change of distance to the test plate. This has been treated by S. Harigovindan and M. V. Rao, “Radiometric errors due to focusing collecting optics at varying object distances,” Appl. Opt. 20, 2590–2594 (1981).
    [Crossref] [PubMed]
  6. This suggests that the observer may experience some averaging of brightness within portions of the object field and/or that diffraction or other optical factors may blur the edge of the bright center area. It should be noted that a distinct transition between penumbral and center fields was never observed during any of these tests.

1981 (1)

1974 (1)

D. A. Palmer, “Mesopic photometry with nonmonochromatic lights,” J. Opt. Soc. Am. 64, 1386 (1974); “Standard observer for large-field photometry at any level,” J. Opt. Soc. Am. 58, 1296–1299 (1968); “The definition of a standard observer for mesopic photometry,” Vision Res. 7, 619–628 (1967).
[PubMed]

1966 (1)

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[Crossref] [PubMed]

Harigovindan, S.

Judd, D. B.

D. B. Judd, “Report of U.S. Secretariat Committee on Colorimetry and Artificial Daylight,” CIE Proc.I(7), 11 (1951).

Palmer, D. A.

D. A. Palmer, “Mesopic photometry with nonmonochromatic lights,” J. Opt. Soc. Am. 64, 1386 (1974); “Standard observer for large-field photometry at any level,” J. Opt. Soc. Am. 58, 1296–1299 (1968); “The definition of a standard observer for mesopic photometry,” Vision Res. 7, 619–628 (1967).
[PubMed]

Rao, M. V.

Stiles, W.

G. Wyszecki and W. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulas (Wiley, New York, 1967), pp. 212–214.

Westheimer, G.

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[Crossref] [PubMed]

Wyszecki, G.

G. Wyszecki and W. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulas (Wiley, New York, 1967), pp. 212–214.

Appl. Opt. (1)

J. Opt. Soc. Am. (1)

D. A. Palmer, “Mesopic photometry with nonmonochromatic lights,” J. Opt. Soc. Am. 64, 1386 (1974); “Standard observer for large-field photometry at any level,” J. Opt. Soc. Am. 58, 1296–1299 (1968); “The definition of a standard observer for mesopic photometry,” Vision Res. 7, 619–628 (1967).
[PubMed]

Vision Res. (1)

G. Westheimer, “The Maxwellian view,” Vision Res. 6, 669–682 (1966).
[Crossref] [PubMed]

Other (3)

D. B. Judd, “Report of U.S. Secretariat Committee on Colorimetry and Artificial Daylight,” CIE Proc.I(7), 11 (1951).

This suggests that the observer may experience some averaging of brightness within portions of the object field and/or that diffraction or other optical factors may blur the edge of the bright center area. It should be noted that a distinct transition between penumbral and center fields was never observed during any of these tests.

G. Wyszecki and W. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulas (Wiley, New York, 1967), pp. 212–214.

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Figures (4)

Fig. 1
Fig. 1

Dimensions of the field of view for the SEI exposure meter and the macbeth illuminometer.

Fig. 2
Fig. 2

Calculated troland values for various test-plate displacements for 490 nm (solid symbols and lines) and 640 nm (open symbols and dashed lines) obtained by means of the SEI exposure meter.

Fig. 3
Fig. 3

The cause of the small-field problem is shown by this schematic of the pattern of light output from a Maxwellian-view optical system. The final Maxwellian lens is shown at (a). The image of the aperture stop at the focal plane of the exit pupil is shown at (b). The field of view of the SEI-meter comparison spot (dashed circles) and the pattern of light cast by the lens on the test plate are shown at (c) and (d) for two distances of test plate from the focal plane. The light pattern is composed of a brighter inner region (white area) and a dimmer penumbral region (stippled area). The SEI meter will yield a lower luminance reading of the test plate at (c) than at (d).

Fig. 4
Fig. 4

Troland value calculated according to Westheimer’s equation3 as a function of test-plate displacement and exit pupil (aperture) diameter in millimeters. The points represent actual measurements. The smooth curves are fitted by eye to the data. The size labeled NONE means that no aperture was used and that the image on the test plate was the size of the filament of the source.

Equations (1)

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d = f ( e + 6 s tan 0.3° ) m - e ,