Abstract

The availability of increased resolution, dispersion, and luminosity from plane gratings at high angles of incidence and diffraction is discussed from the standpoints of theory and practice. Reduction in the resolution given by actual gratings at angles above a certain maximum for a given wavelength usually arises from close-lying line-satellites originating from ruling defects. Variation of satellite displacements and intensities with wavelength gives rise to such undesirable effects as error of coincidence. The bright 10-in. gratings now produced by the M.I.T. interferometrically controlled engine can be used effectively at very high angles (12th-order green from 7500 grooves per inch), but as in all gratings the angle above which resolution fails to increase further diminishes with decreasing wavelength. The pattern dimensions and intensities of satellites are here discussed qualitatively as they affect resolution in various spectral regions, and are quantitatively discussed by one of us elsewhere.

The use of gratings and echelles in series for increasing spectroscopic efficiency is discussed, and spectrograms made with two echelles thus used are shown. Two gratings used in series transmit only a narrow wavelength range at one setting because of the wide angular spread of the beam from the first disperser. An echelle beam, on the other hand, spreads but little, and can be caught on a second echelle to give broad spectral coverage. Two echelles used in series give high speed and resolution without the careful relative adjustment required to produce a satisfactory grating mosaic.

© 1960 Optical Society of America

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References

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  1. G. R. Harrison, Proc. Am. Phil. Soc. 102, 483 (1958); (a)G. R. Harrison, N. Sturgis, S. P. Davis, and Y. Yamada, J. Opt. Soc. Am. 49, 205 (1959).
  2. A. Keith Pierce, J. Opt. Soc. Am. 48, 6 (1957); (a)G. R. Harrison, N. Sturgis, S. C. Baker, and G. W. Stroke, ibid. 47, 15 (1957).
    [CrossRef]
  3. See G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1948), or footnote references 1a or 2a.
  4. Rayleigh, Phil. Mag. 47, 81 and 193 (1874).
  5. H. A. Rowland, Phil. Mag. 35, 397 (1893).
  6. A. A. Michelson, Nature 88, 362 (1912).
    [CrossRef]
  7. H. A. Rowland, Physical Papers (Johns Hopkins Press, Homewood, Baltimore, Maryland, 1902).
  8. G. W. Stroke, Preprints and Proceedings Interferometry Symposium, N.P.L., Teddington, June 10, 1959; Paper No. 5, 5th Conf. I.C.O.StockholmAugust 24, 1959; Rev. opt.,  39, 291 (1960).
  9. J. A. Anderson, J. Opt. Soc. Am. 6, 434 (1922).
  10. R. W. Wood (unpublished communication in 1932).
  11. H. D. Babcock and H. W. Babcock, J. Opt. Soc. Am. 41, 776 (1951).
    [CrossRef]
  12. E. Ingelstam and E. Djurle, J. Opt. Soc. Am. 43, 572 (1953).
    [CrossRef]
  13. A. A. Michelson, Astrophys. J. 18, 278 (1903).
    [CrossRef]
  14. E. Ingelstam and E. Djurle, footnote reference 12 and Arkiv Fysik 4, 423 (1952); Arkiv Fysik 6, 463 (1953).
  15. G. W. Stroke, J. Opt. Soc. Am. 45, 30 (1955).
    [CrossRef]
  16. Pierce gives a similar plot at one wavelength for an 8-in. Mt. Wilson grating, in which the satellites are somewhat stronger, are more numerous, and cover a broader range;aA. K. Pierce, J. Opt. Soc. Am. 47, 10 (1957).
  17. G. R. Harrison, S. P. Davis, and H. J. Robertson, J. Opt. Soc. Am. 43, 853 (1953).
    [CrossRef]
  18. D. Richardson (verbal communication, 1959).
  19. J. Walsh, Nature 167, 810 (1951); J. Opt. Soc. Am. 42, 94 (1952).
    [CrossRef] [PubMed]
  20. E. Hulthén and E. Lind, Arkik Fysik. 2, 253 (1950); E. Hulthén and H. Neuhaus, ibid. 8, 343 (1954).
  21. D. H. Rank and T. A. Wiggins, J. Opt. Soc. Am. 42, 983 (1952).
    [CrossRef]
  22. F. A. Jenkins and L. W. Alvarez, J. Opt. Soc. Am. 42, 699 (1952).
    [CrossRef]
  23. G. W. Stroke and H. H. Stroke, Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol.October15, 1954, p. 54.
  24. G. R. Harrison, J. Opt. Soc. Am. 39, 522 (1949); G. R. Harrison and C. L. Bausch, Proceedings of the London Conference of the Optical Institute (Chapman and Hall, Ltd., London, 1950); G. R. Harrison, J. E. Archer, and J. Camus, J. Opt. Soc. Am. 42, 706 (1925); G. R. Harrison, S. P. Davis, and H. J. Robertson, ibid. 43, 853 (1953).
    [CrossRef]

1958 (1)

G. R. Harrison, Proc. Am. Phil. Soc. 102, 483 (1958); (a)G. R. Harrison, N. Sturgis, S. P. Davis, and Y. Yamada, J. Opt. Soc. Am. 49, 205 (1959).

1957 (2)

A. Keith Pierce, J. Opt. Soc. Am. 48, 6 (1957); (a)G. R. Harrison, N. Sturgis, S. C. Baker, and G. W. Stroke, ibid. 47, 15 (1957).
[CrossRef]

Pierce gives a similar plot at one wavelength for an 8-in. Mt. Wilson grating, in which the satellites are somewhat stronger, are more numerous, and cover a broader range;aA. K. Pierce, J. Opt. Soc. Am. 47, 10 (1957).

1955 (1)

1954 (1)

G. W. Stroke and H. H. Stroke, Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol.October15, 1954, p. 54.

1953 (2)

1952 (2)

1951 (2)

H. D. Babcock and H. W. Babcock, J. Opt. Soc. Am. 41, 776 (1951).
[CrossRef]

J. Walsh, Nature 167, 810 (1951); J. Opt. Soc. Am. 42, 94 (1952).
[CrossRef] [PubMed]

1950 (1)

E. Hulthén and E. Lind, Arkik Fysik. 2, 253 (1950); E. Hulthén and H. Neuhaus, ibid. 8, 343 (1954).

1949 (1)

1922 (1)

1912 (1)

A. A. Michelson, Nature 88, 362 (1912).
[CrossRef]

1903 (1)

A. A. Michelson, Astrophys. J. 18, 278 (1903).
[CrossRef]

1893 (1)

H. A. Rowland, Phil. Mag. 35, 397 (1893).

1874 (1)

Rayleigh, Phil. Mag. 47, 81 and 193 (1874).

Alvarez, L. W.

Anderson, J. A.

Babcock, H. D.

Babcock, H. W.

Davis, S. P.

Djurle, E.

E. Ingelstam and E. Djurle, J. Opt. Soc. Am. 43, 572 (1953).
[CrossRef]

E. Ingelstam and E. Djurle, footnote reference 12 and Arkiv Fysik 4, 423 (1952); Arkiv Fysik 6, 463 (1953).

Harrison, G. R.

G. R. Harrison, Proc. Am. Phil. Soc. 102, 483 (1958); (a)G. R. Harrison, N. Sturgis, S. P. Davis, and Y. Yamada, J. Opt. Soc. Am. 49, 205 (1959).

G. R. Harrison, S. P. Davis, and H. J. Robertson, J. Opt. Soc. Am. 43, 853 (1953).
[CrossRef]

G. R. Harrison, J. Opt. Soc. Am. 39, 522 (1949); G. R. Harrison and C. L. Bausch, Proceedings of the London Conference of the Optical Institute (Chapman and Hall, Ltd., London, 1950); G. R. Harrison, J. E. Archer, and J. Camus, J. Opt. Soc. Am. 42, 706 (1925); G. R. Harrison, S. P. Davis, and H. J. Robertson, ibid. 43, 853 (1953).
[CrossRef]

See G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1948), or footnote references 1a or 2a.

Hulthén, E.

E. Hulthén and E. Lind, Arkik Fysik. 2, 253 (1950); E. Hulthén and H. Neuhaus, ibid. 8, 343 (1954).

Ingelstam, E.

E. Ingelstam and E. Djurle, J. Opt. Soc. Am. 43, 572 (1953).
[CrossRef]

E. Ingelstam and E. Djurle, footnote reference 12 and Arkiv Fysik 4, 423 (1952); Arkiv Fysik 6, 463 (1953).

Jenkins, F. A.

Keith Pierce, A.

A. Keith Pierce, J. Opt. Soc. Am. 48, 6 (1957); (a)G. R. Harrison, N. Sturgis, S. C. Baker, and G. W. Stroke, ibid. 47, 15 (1957).
[CrossRef]

Lind, E.

E. Hulthén and E. Lind, Arkik Fysik. 2, 253 (1950); E. Hulthén and H. Neuhaus, ibid. 8, 343 (1954).

Loofbourow, J. R.

See G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1948), or footnote references 1a or 2a.

Lord, R. C.

See G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1948), or footnote references 1a or 2a.

Michelson, A. A.

A. A. Michelson, Nature 88, 362 (1912).
[CrossRef]

A. A. Michelson, Astrophys. J. 18, 278 (1903).
[CrossRef]

Pierce, A. K.

Pierce gives a similar plot at one wavelength for an 8-in. Mt. Wilson grating, in which the satellites are somewhat stronger, are more numerous, and cover a broader range;aA. K. Pierce, J. Opt. Soc. Am. 47, 10 (1957).

Rank, D. H.

Rayleigh,

Rayleigh, Phil. Mag. 47, 81 and 193 (1874).

Richardson, D.

D. Richardson (verbal communication, 1959).

Robertson, H. J.

Rowland, H. A.

H. A. Rowland, Phil. Mag. 35, 397 (1893).

H. A. Rowland, Physical Papers (Johns Hopkins Press, Homewood, Baltimore, Maryland, 1902).

Stroke, G. W.

G. W. Stroke, J. Opt. Soc. Am. 45, 30 (1955).
[CrossRef]

G. W. Stroke and H. H. Stroke, Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol.October15, 1954, p. 54.

G. W. Stroke, Preprints and Proceedings Interferometry Symposium, N.P.L., Teddington, June 10, 1959; Paper No. 5, 5th Conf. I.C.O.StockholmAugust 24, 1959; Rev. opt.,  39, 291 (1960).

Stroke, H. H.

G. W. Stroke and H. H. Stroke, Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol.October15, 1954, p. 54.

Walsh, J.

J. Walsh, Nature 167, 810 (1951); J. Opt. Soc. Am. 42, 94 (1952).
[CrossRef] [PubMed]

Wiggins, T. A.

Wood, R. W.

R. W. Wood (unpublished communication in 1932).

Arkik Fysik. (1)

E. Hulthén and E. Lind, Arkik Fysik. 2, 253 (1950); E. Hulthén and H. Neuhaus, ibid. 8, 343 (1954).

Astrophys. J. (1)

A. A. Michelson, Astrophys. J. 18, 278 (1903).
[CrossRef]

J. Opt. Soc. Am. (10)

Nature (2)

J. Walsh, Nature 167, 810 (1951); J. Opt. Soc. Am. 42, 94 (1952).
[CrossRef] [PubMed]

A. A. Michelson, Nature 88, 362 (1912).
[CrossRef]

Phil. Mag. (2)

Rayleigh, Phil. Mag. 47, 81 and 193 (1874).

H. A. Rowland, Phil. Mag. 35, 397 (1893).

Proc. Am. Phil. Soc. (1)

G. R. Harrison, Proc. Am. Phil. Soc. 102, 483 (1958); (a)G. R. Harrison, N. Sturgis, S. P. Davis, and Y. Yamada, J. Opt. Soc. Am. 49, 205 (1959).

Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol. (1)

G. W. Stroke and H. H. Stroke, Quart. Progr. Rept., Research Lab. of Electronics, Mass. Inst. Technol.October15, 1954, p. 54.

Other (6)

See G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy (Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1948), or footnote references 1a or 2a.

H. A. Rowland, Physical Papers (Johns Hopkins Press, Homewood, Baltimore, Maryland, 1902).

G. W. Stroke, Preprints and Proceedings Interferometry Symposium, N.P.L., Teddington, June 10, 1959; Paper No. 5, 5th Conf. I.C.O.StockholmAugust 24, 1959; Rev. opt.,  39, 291 (1960).

R. W. Wood (unpublished communication in 1932).

D. Richardson (verbal communication, 1959).

E. Ingelstam and E. Djurle, footnote reference 12 and Arkiv Fysik 4, 423 (1952); Arkiv Fysik 6, 463 (1953).

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Figures (7)

Fig. 1
Fig. 1

Curves showing variation of resolving power and dispersion with angle of use for a grating or echelle in autocollimation. With rectangular grooves the choice between two blaze angles greatly affects both variables.

Fig. 2
Fig. 2

Curve showing theoretical variation of Rowland ghost intensity relative to the parent line with angle of use of a grating or echelle in autocollimation.

Fig. 3
Fig. 3

Twyman-Green interferometer test pattern at 64° 25′ showing fringe variations of types responsible for close satellites, and hence for loss in resolution and error of coincidence in gratings.

Fig. 4
Fig. 4

Satellite structures of two strong lines of Hg 198 compared on the same plate scale to that of λ 5461, taken on a 12-m spectrograph through a step-sector at approximately the same angles.

Fig. 5
Fig. 5

Logarithmic plot of satellite intensities for two widely differing wavelengths, as determined from Fig. 4. The total width of the pattern for λ 5461 is 0.15 A, while that for λ 2537 is 0.12 A. The respective dispersions are 9.35 mm/A and 21.6 mm/A.

Fig. 6
Fig. 6

Experimental spectrograph setup in which the spectrum produced by two parallel echelles in series is crossed with that of a concave grating in parallel light, to combine high resolution and dispersion with broad spectral coverage.

Fig. 7
Fig. 7

Sections of spectrograms taken with the echelle—echelle—concave grating arrangement of Fig. 6. Two 4-in. echelles suffice to resolve the central structure. (a) hfs structure of Hg λ 5461. (b) shorter exposure to the five central components, wavelength scale reversed from (a).