Abstract

An automatic recording spectrophotometer for the infrared is described, which employs a double-beam source, Littrow spectrometer, fast bolometer, and high speed pen- and drum-recording system. The sample and reference beams are alternately chopped at 10 cycles/sec. at the entrance slit to the spectrometer. The amplified a.c. signal on the bolometer is used to drive a variable comb diaphragm in the reference beam. The spectra are registered on a recorder by a pen mechanically linked to this comb.

The spectral region covered is between 2 microns and 16 microns with a sodium chloride prism. The range can be extended to about 26 microns by the use of a potassium bromide prism. The instrument is designed for high speed analytical work, producing permanently recorded spectrograms of gases, liquids, and solids on accurate charts at intervals of 18 minutes. Percent transmission is recorded with an accuracy of ±1 percent, and wave-length with an accuracy of ±0.025 micron. Records are reproducible to within ±1 percent transmission and ±0.01 micron.

Special features are its high recording speed, stability and freedom from drift with the “optical-null” principle, linearity and ease of operation.

© 1947 Optical Society of America

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References

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  1. J. D. Hardy and A. I. Ryer, Phys. Rev. 55, 1112 (1939).
  2. N. Wright and L. W. Herscher, “Double-beam, percent transmission recording infra-red spectrophotometer,” J. Opt. Soc. Am. 37, 211 (1947).
    [Crossref] [PubMed]
  3. E. Lehrer, Zeits. f. tech. Physik 23, 169 (1942).
  4. Schaefer and Matossi, Das ultrarote Spectrum (J. Springer Verlag, Berlin, 1930), p. 47.

1947 (1)

1942 (1)

E. Lehrer, Zeits. f. tech. Physik 23, 169 (1942).

1939 (1)

J. D. Hardy and A. I. Ryer, Phys. Rev. 55, 1112 (1939).

Hardy, J. D.

J. D. Hardy and A. I. Ryer, Phys. Rev. 55, 1112 (1939).

Herscher, L. W.

Lehrer, E.

E. Lehrer, Zeits. f. tech. Physik 23, 169 (1942).

Matossi,

Schaefer and Matossi, Das ultrarote Spectrum (J. Springer Verlag, Berlin, 1930), p. 47.

Ryer, A. I.

J. D. Hardy and A. I. Ryer, Phys. Rev. 55, 1112 (1939).

Schaefer,

Schaefer and Matossi, Das ultrarote Spectrum (J. Springer Verlag, Berlin, 1930), p. 47.

Wright, N.

J. Opt. Soc. Am. (1)

Phys. Rev. (1)

J. D. Hardy and A. I. Ryer, Phys. Rev. 55, 1112 (1939).

Zeits. f. tech. Physik (1)

E. Lehrer, Zeits. f. tech. Physik 23, 169 (1942).

Other (1)

Schaefer and Matossi, Das ultrarote Spectrum (J. Springer Verlag, Berlin, 1930), p. 47.

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Figures (8)

F. 1
F. 1

Null system.

F. 2
F. 2

Spectrometer.

F. 3
F. 3

Voltage amplifier—infra-red spectrophotometer.

F. 5
F. 5

Ammonia spectrum.

F. 6
F. 6

Cholesterol in carbon disulfide; blank cell in reference beam.

F. 7
F. 7

Cholesterol in carbon disulfide; carbon disulfide in reference beam; compare with Fig. 6 and note cancellation of CS2 bands.

F. 8
F. 8

Absorption spectrum of 0.025″ polystyrene film.

Tables (1)

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Table I

Equations (7)

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

sin ( r ) = sin ( i ) / n ,
( i ) = A ( r ) ,
sin ( r ) = n sin ( i ) ,
i λ 1 = 2 r λ r λ 1 ,
i λ 2 = 2 r λ r λ 2 ,
d λ / d y d λ / σ d r ,
Δ λ D = d λ / d y × the slit width .