Abstract

A device is described which can be attached to any standard moving-plate comparator which automatically records the passage of the density maximum of a spectrum line, computes the wavelength corresponding to this maximum and records this value to eight figures photographically at high speed. The automatic recording, computing and measuring features can be used independently if desired. The comparator screw can be driven by hand, or by electric motor at controllable speed, through a shaft which is coupled to a wavelength shaft by means of variable ratio gears and a differential so that the speed ratio of the shafts can be rapidly adjusted to any desired instantaneous value. When measuring a plate the operator sees on a screen before him a magnified image of a portion of the spectrum; the light in this image actuates an amplifier system through three photo-cells to give records of plate density and rate of change of density with distance. When the density slope becomes zero while the density is greater than some predetermined background value a mercury arc flashes to record the wavelength dial readings. Correct wavelength readings for any desired number of standard lines can be set into the machine, or an empirical dispersion formula can be introduced. Errors due to backlash, oil film variation and temperature variation of the screw are practically eliminated, and automatic setting on most lines is found to be more accurate than hand setting. A microphotometer trace is superposed by the machine on the wavelength list so that the intensities and physical characteristics of lines can be determined directly. A ten to 200-fold gain in speed of measurement of complex spectrograms results from use of the machine. When used as a microphotometer the instrument is faster than those in common use.

© 1935 Optical Society of America

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References

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  1. G. R. Harrison, Phys. Rev. 45, 760 (1934).
  2. G. R. Harrison, J. Opt. Soc. Am. 19, 301 (1929).
  3. H. Kayser, Handbuch der Spektroskopie, Vol.  I, p. 644. Kayser says this device saved over half the time previously required for plate measurement.See also O. Lohse, Zeits. f. Inst.,  30, 169 (1910).
  4. H. E. Edgerton and K. J. Germeshausen, Rev. Sci. Inst. 3, 535 (1932).
    [Crossref]
  5. L. G. Hoxton, Phys. Rev. 10, 90 (1917);J. Opt. Soc. Am. and Rev. Sci. Inst. 18, 442 (1929); Hoxton and D. W. Mann, Bull. Am. Phys. Soc. 10, 8 (1935).S. Grassmann, Physik. Zeits. 32, 148 (1931).H. Conrad-Billroth, Zeits. f. Inst. 54, 301 (1934).
  6. J. W. Horton, J. Frank. Inst. 216, 749 (1933). I am greatly indebted to Dr. Horton for calling the possibilities of his amplifier to my attention in this connection, and for much valuable advice regarding the electrical circuits used in the line-setting device.
    [Crossref]
  7. F. W. Sears, J. Opt. Soc. Am. 25, 162 (1935).
    [Crossref]
  8. A. C. Hardy, J. Opt. Soc. Am. 24, 162 (1934).

1935 (1)

1934 (2)

A. C. Hardy, J. Opt. Soc. Am. 24, 162 (1934).

G. R. Harrison, Phys. Rev. 45, 760 (1934).

1933 (1)

J. W. Horton, J. Frank. Inst. 216, 749 (1933). I am greatly indebted to Dr. Horton for calling the possibilities of his amplifier to my attention in this connection, and for much valuable advice regarding the electrical circuits used in the line-setting device.
[Crossref]

1932 (1)

H. E. Edgerton and K. J. Germeshausen, Rev. Sci. Inst. 3, 535 (1932).
[Crossref]

1929 (1)

G. R. Harrison, J. Opt. Soc. Am. 19, 301 (1929).

1917 (1)

L. G. Hoxton, Phys. Rev. 10, 90 (1917);J. Opt. Soc. Am. and Rev. Sci. Inst. 18, 442 (1929); Hoxton and D. W. Mann, Bull. Am. Phys. Soc. 10, 8 (1935).S. Grassmann, Physik. Zeits. 32, 148 (1931).H. Conrad-Billroth, Zeits. f. Inst. 54, 301 (1934).

Edgerton, H. E.

H. E. Edgerton and K. J. Germeshausen, Rev. Sci. Inst. 3, 535 (1932).
[Crossref]

Germeshausen, K. J.

H. E. Edgerton and K. J. Germeshausen, Rev. Sci. Inst. 3, 535 (1932).
[Crossref]

Hardy, A. C.

A. C. Hardy, J. Opt. Soc. Am. 24, 162 (1934).

Harrison, G. R.

G. R. Harrison, Phys. Rev. 45, 760 (1934).

G. R. Harrison, J. Opt. Soc. Am. 19, 301 (1929).

Horton, J. W.

J. W. Horton, J. Frank. Inst. 216, 749 (1933). I am greatly indebted to Dr. Horton for calling the possibilities of his amplifier to my attention in this connection, and for much valuable advice regarding the electrical circuits used in the line-setting device.
[Crossref]

Hoxton, L. G.

L. G. Hoxton, Phys. Rev. 10, 90 (1917);J. Opt. Soc. Am. and Rev. Sci. Inst. 18, 442 (1929); Hoxton and D. W. Mann, Bull. Am. Phys. Soc. 10, 8 (1935).S. Grassmann, Physik. Zeits. 32, 148 (1931).H. Conrad-Billroth, Zeits. f. Inst. 54, 301 (1934).

Kayser, H.

H. Kayser, Handbuch der Spektroskopie, Vol.  I, p. 644. Kayser says this device saved over half the time previously required for plate measurement.See also O. Lohse, Zeits. f. Inst.,  30, 169 (1910).

Sears, F. W.

Handbuch der Spektroskopie (1)

H. Kayser, Handbuch der Spektroskopie, Vol.  I, p. 644. Kayser says this device saved over half the time previously required for plate measurement.See also O. Lohse, Zeits. f. Inst.,  30, 169 (1910).

J. Frank. Inst. (1)

J. W. Horton, J. Frank. Inst. 216, 749 (1933). I am greatly indebted to Dr. Horton for calling the possibilities of his amplifier to my attention in this connection, and for much valuable advice regarding the electrical circuits used in the line-setting device.
[Crossref]

J. Opt. Soc. Am. (3)

F. W. Sears, J. Opt. Soc. Am. 25, 162 (1935).
[Crossref]

A. C. Hardy, J. Opt. Soc. Am. 24, 162 (1934).

G. R. Harrison, J. Opt. Soc. Am. 19, 301 (1929).

Phys. Rev. (2)

G. R. Harrison, Phys. Rev. 45, 760 (1934).

L. G. Hoxton, Phys. Rev. 10, 90 (1917);J. Opt. Soc. Am. and Rev. Sci. Inst. 18, 442 (1929); Hoxton and D. W. Mann, Bull. Am. Phys. Soc. 10, 8 (1935).S. Grassmann, Physik. Zeits. 32, 148 (1931).H. Conrad-Billroth, Zeits. f. Inst. 54, 301 (1934).

Rev. Sci. Inst. (1)

H. E. Edgerton and K. J. Germeshausen, Rev. Sci. Inst. 3, 535 (1932).
[Crossref]

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Figures (8)

F. 1
F. 1

View of the reducing and recording machine and the comparator belted together. An image of the spectrogram is projected on the opaque screen S for automatic recording, and on ground-glass screen S′ where the operator can observe it.

F. 2
F. 2

(a) Portion of a wavelength record with uniform spacing and with intensity marks omitted; (b) Portion of a wavelength record with spacing proportional to wavelength, with a simultaneously recorded density curve. The recording camera was here driven with the middle speed of three provided from the wavelength shaft S″ of Fig. 3. The recorder was set to give medium and strong lines only.

F. 3
F. 3

Diagram of the comparator and reducing machine, showing the relationship of the principal mechanical parts.

F. 4
F. 4

Diagram of the mechanical system used to control rotation of the rim of differential L, to introduce dispersion variation.

F. 5
F. 5

View of the rear of the reducing machine, showing the template C for automatic dispersion variation, the drum L containing a rotating print of the iron spectrum, and the two nosepieces on the recording camera. The wavelengths are photographed through the downward pointing nosepiece, while the light beam from oscillograph O enters at P through a cylindrical lens.

F. 6
F. 6

Diagram of the optical system used to get a 3000-cycle beam of light for automatic recording, and an extra observing beam.

F. 7
F. 7

The electrical circuits used to flash the mercury arc whenever the light intensities on cells A and C are equal, if the light on cell B has fallen below a predetermined value. Both amplifiers are tuned broadly to 3000 cycles, giving fairly uniform response between 2600 and 3400 cycles to allow of modulation between 0 and 400 cycles in crossing spectrum lines at high speed.

F. 8
F. 8

Typical curves obtained in crossing a spectrum line: B, the amplified current from cell B, giving the density trace and operating the line-selector relay; AC, the amplified difference current from cells A and C, giving the density slope at any instant; H, the voltage from a d.c. amplifier into which voltage following curve AC has been sent, the amplifier being saturated except when AC falls to within 0.25 volt of its minimum value. The width of the slit in screen S used in obtaining the curves is as shown. It was set for a resolution of about 200,000; the shaded regions are those whose light is thrown by glass rhombs on cells A and C, respectively, while light entering region B is used to make the density trace.