Abstract

The General Radio Strobolux unit triggered by a Strobotac has been used extensively in this laboratory for visual threshold determinations. This photometric study was undertaken to provide information on the duration of the flash and the constancy of the total energy for successive flashes. By using a standardized ribbon filament lamp for a comparison source and four narrow pass filters, the total energy per flash in absolute units was found for four spectral regions. A high-speed camera developed by O’Brien was used for the photographic record. A narrow slit illuminated by the Strobolux was imaged on a strip of 16-mm Super-XX film carried on the inner circumference of a drum mounted on the shaft of a vertical motor. When the drum was driven at 10 800 rpm, the exposure time on the film was 0.236 µsec. The film was calibrated by exposing a standard lamp through a stepped slit on the same record. The peak luminance through a 550-mµ interference filter is 7660 c/cm2 of tube area. The duration of the flash is about 100 µsec with 90% of the energy delivered in 41 µsec.

© 1959 Optical Society of America

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References

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  1. H. E. Edgerton, J. Opt. Soc. Am. 36, 390 (1946).
    [Crossref]
  2. Brian O’Brien, Phys. Rev. 50, 400 (1936).
  3. B. T. Barnes and W. E. Forsythe, J. Opt. Soc. Am. 26, 313 (1936).
    [Crossref]
  4. G. G. Milne, J. Opt. Soc. Am. 40, 799 (1950).
  5. G. G. Milne, Dissertation (University of Rochester, 1950).

1950 (1)

G. G. Milne, J. Opt. Soc. Am. 40, 799 (1950).

1946 (1)

1936 (2)

Barnes, B. T.

Edgerton, H. E.

Forsythe, W. E.

Milne, G. G.

G. G. Milne, J. Opt. Soc. Am. 40, 799 (1950).

G. G. Milne, Dissertation (University of Rochester, 1950).

O’Brien, Brian

Brian O’Brien, Phys. Rev. 50, 400 (1936).

J. Opt. Soc. Am. (3)

Phys. Rev. (1)

Brian O’Brien, Phys. Rev. 50, 400 (1936).

Other (1)

G. G. Milne, Dissertation (University of Rochester, 1950).

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Figures (7)

F. 1
F. 1

Schematic drawing of the high-speed camera and source arrangement.

F. 2
F. 2

Microdensitometer trace of a Strobolux flash exposure and the characteristic curve of Super-XX film derived from the standard lamp exposures with construction lines to indicate the method of reducing the trace to exposure terms.

F. 3
F. 3

Spectral steradiance of a tungsten ribbon filament as a function of color temperature with wavelength as the parameter; the data is from Barnes and Forsythe.3

F. 4
F. 4

Spectral transmittance curves of the isolating filters with the spectral steradiance of tungsten ribbon for the color temperature of the standard lamp.

F. 5
F. 5

The logarithm of the steradiance of the Strobolux tube measured through each of the filters as a function of time for the low-speed condensers. The characteristics of discharge for the medium and high speed condensers is also shown for one filter. The open circles on the curves are the measured values when the 1.0 density neutral filter was added to the color filter over the camera lens.

F. 6
F. 6

The integrated energy per flash of the Strobolux tube for the four wavelength bands studied reduced to a constant wavelength interval indicating the presence of line structure in the gas discharge.

F. 7
F. 7

Reciprocity curve for Super-XX film for short exposure times.5

Tables (3)

Tables Icon

Table I Spectral steradiance of ribbon filament tungsten lamp operated at 2947° color temperature. The values were interpolated from the data of Barnes and Forsythe.3 The wavelength λ is in mµ and Eλ is in w/cm2/sterad/10 mµ.

Tables Icon

Table II The widths of the stepped slit used in making the standard tungsten exposures with the resulting exposure times for the drum speeds indicated. The widths are given in mm and the times in sec.

Tables Icon

Table III The total energy per flash of the Strobolux tube in ergs/cm2/sterad through each of the filters. The peak radiance through each of the filters is also shown in w/cm2/sterad.