Abstract

No abstract available.

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. Buisson Fabry and Bourget, Aph. J. 40, 241; 1914.
  2. Campbell, Aph. J.,  10, 186; 1899.
    [Crossref]
  3. Freeman, Aph. J.,  68, 177; 1928.
    [Crossref]
  4. The specifications for such etalon plates may possibly be of interest to observers in allied fields.Each plate to be 80 mm in diameter and 10 to 12 mm thick. The rear surfaces should be plane at least to 1 wave; the front (opposing) surfaces must be plane at least to 1/20 wave over a central area 6 cm in diameter; the edges of these faces may fall off a little in accuracy. The etalon plates must not have precisely parallel faces, but should make an angle of 3 to 8 minutes of arc with each other, and a mark (a small arrow) should be etched on the ground edge of each plate indicating the thicker side and pointing to the “good” faces. These faces should be silvered or platinized to a thickness which will transmit approximately 40% of the incident light.Any glass filter used should likewise be very slightly wedge-shaped, truly parallel etalon or filter plates will display their own inherent fringe system, which will cause confusion in adjustment and in the interpretation of results.Separators of the type used in the Allegheny instruments are quite easy to make. These consist of a bronze ring into which are forced three short pins of the best, tested invar. With file and oilstone these pins are first brought within about.0001 inch of the same length as measured with a micrometer, and the ends of the pins are somewhat rounded. The separator is then placed between the etalon plates and the whole laid on a plate of glass through which passes the light from a mercury lamp reflected from a diagonal mirror beneath. By exerting some pressure on each of the pins one can quickly locate the pins which are too long through the appearance of the interference rings. The longer pins are honed down by very light touches with a hard, fine oil stone, with repeated testings, until a round and well-centered ring system is obtained under very light and uniform pressure of the plates on the separator.

1928 (1)

Freeman, Aph. J.,  68, 177; 1928.
[Crossref]

1914 (1)

Buisson Fabry and Bourget, Aph. J. 40, 241; 1914.

1899 (1)

Campbell, Aph. J.,  10, 186; 1899.
[Crossref]

Bourget,

Buisson Fabry and Bourget, Aph. J. 40, 241; 1914.

Campbell,

Campbell, Aph. J.,  10, 186; 1899.
[Crossref]

Fabry, Buisson

Buisson Fabry and Bourget, Aph. J. 40, 241; 1914.

Freeman,

Freeman, Aph. J.,  68, 177; 1928.
[Crossref]

Aph. J. (3)

Buisson Fabry and Bourget, Aph. J. 40, 241; 1914.

Campbell, Aph. J.,  10, 186; 1899.
[Crossref]

Freeman, Aph. J.,  68, 177; 1928.
[Crossref]

Other (1)

The specifications for such etalon plates may possibly be of interest to observers in allied fields.Each plate to be 80 mm in diameter and 10 to 12 mm thick. The rear surfaces should be plane at least to 1 wave; the front (opposing) surfaces must be plane at least to 1/20 wave over a central area 6 cm in diameter; the edges of these faces may fall off a little in accuracy. The etalon plates must not have precisely parallel faces, but should make an angle of 3 to 8 minutes of arc with each other, and a mark (a small arrow) should be etched on the ground edge of each plate indicating the thicker side and pointing to the “good” faces. These faces should be silvered or platinized to a thickness which will transmit approximately 40% of the incident light.Any glass filter used should likewise be very slightly wedge-shaped, truly parallel etalon or filter plates will display their own inherent fringe system, which will cause confusion in adjustment and in the interpretation of results.Separators of the type used in the Allegheny instruments are quite easy to make. These consist of a bronze ring into which are forced three short pins of the best, tested invar. With file and oilstone these pins are first brought within about.0001 inch of the same length as measured with a micrometer, and the ends of the pins are somewhat rounded. The separator is then placed between the etalon plates and the whole laid on a plate of glass through which passes the light from a mercury lamp reflected from a diagonal mirror beneath. By exerting some pressure on each of the pins one can quickly locate the pins which are too long through the appearance of the interference rings. The longer pins are honed down by very light touches with a hard, fine oil stone, with repeated testings, until a round and well-centered ring system is obtained under very light and uniform pressure of the plates on the separator.

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (5)

F. 1
F. 1

Interferometers mounted on polar axis at Takengon. Interferometer for the line 3388A. SOUV.Interferometer for the line 5303A, AOG.Interferometer for the line 3388A, AOUV.An infrared grating spectrograph, unnumbered, is mounted on the farther side of the axis.

F. 2
F. 2

The Sproul Observatory green interferometer, SOG. A, is a 60° prism of light flint glass, used in 1925 and 1926.B, the Minus Blue Wratten filter.C, a two-piece objective, aperture 5 cm, focal length 40 cm.D, a neon tube that was inserted in the focal plane of C when forming the comparison interference rings.E, a Ramsden eyepiece, focal length 10 cm.F, the etalon.G, a two-piece objective, aperture 2 cm, focal length 25 cm.H, the plate-holder, taking 3 1/4×4 1/4 inch plates.

F. 3
F. 3

The Allegheny Observatory green interferometer, AOG. A, is an excellent light flint glass prism of 60° angle and 11.5 cm on a face, made originally for Langley. Deviation 44° 43′ for. 5303A.B, the helium comparison tube; C, a ground glass screen; D, the comparison lens of 25 cm focal length, sending parallel light through the system by reflection from the rear prism face.E, a frame which can be removed at will, holding a gelatine filter 10 cm square.F, the hinged aluminum exposure window.G, a four-piece doublet, aperture 10 cm, focal length 53 cm, giving, with the large ocular, H, a magnification of about 6×.I, the etalon and holder.J, a Cooke-Taylor camera lens of 5 cm aperture and 21 cm focal length.K, a brass comparison diaphragm plate, pierced by two slots at right angles making an angle of 45° with the dispersion; each slot is about 0.6 mm wide and 8 cm long. This diaphragm is moved to one side for the eclipse exposure; it is, in addition, so mounted on slides that it can be adjusted by means of knurled head screws (not shown), in connection with similar means of adjustment on the etalon holder and its slide, so that the cross formed by the two slits can be accurately centered with the interference ring system.L, the plate-holder, taking 31/4×41/4 inch plates.

F. 4
F. 4

The Allegheny Observatory ultraviolet interferometer, AOUV. A, is the hinged exposing cap.B, C, and D, respectively, are the helium comparison tube, the ground glass diffusing screen, and a comparison lens of 25 cm focal length. This comparison system is mounted as a unit on guides so that it can be pulled to one side of the optical axis by the handle, E.F, and G, are the two lenses of fused quartz forming the telescopic magnification system. These are respectively 5 cm and 2.5 cm in aperture, and 30 cm and 7.5 cm focal lengths, giving a magnification factor of 4. They were made by Fecker, and are of meniscus form to minimize some of the aberrations.H, is the UG 1 glass filter, about 3 cm in diameter and 2 mm thick, mounted on ways so that it can be pulled to one side of the optical axis by means of the handle, I.J, is the etalon, of fused quartz, and its cell.K, is a quartz-fluorite lens of 2.5 cm aperture and 25 cm focal length, which gives a flat field from2,000A to 8,000A.L, a diaphragm plate with crossed slits as in AOG, removable by the handle, M, and provided with centering adjustments.N, the plate-holder, for 31/4×41/4 inch plates.

F. 5
F. 5

The Sproul Observatory ultraviolet interferometer, SOUV. A, is the filter cell, so mounted as to be removable from the train.B, the etalon.C, a quartz meniscus lens, aperture 2 cm, focal length 50 cm.D, the screen with slots and circular aperture.E, the plate-holder, for plates 31/4×41/4 inches in size.F, a helium tube mounted in the train in the focal plane of G when making the comparison rings.G, a quartz lens of 25 cm focal length, which replaced the filter cell A when F was used.

Tables (3)

Tables Icon

Table 1 Advisable upper limits of etalon separation for various atomic masses and temperatures

Tables Icon

Table 3 Exposure and filter data

Equations (2)

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

N = 1.22 × 10 6 m / T abs
R = 57.3 n λ / e