Abstract

The application of laser technology has been extended to optical shop testing by incorporating a cw, helium–neon gas laser in a package that houses a modified Twyman–Green interferometer. This modification provides for optical testing over large path differences with an auxiliary set of lenses used in the long path and a small reference flat used in the short path of the interferometer. With this technique, f/0.7 spherical mirrors have been tested (at the center of curvature) to an accuracy of 110 wavelength at the surface, and various other optical systems have been tested in both double pass and single pass. Two of the advantages of this testing method are (1) the capability of testing spherical concave surfaces without physically contacting the surface and (2) the ability to use small reference surfaces for large optical components or systems. The device known as a laser unequal path interferometer can be used with a set of null lenses to qualify aspheric surfaces. The unit is portable and capable of testing in any orientation under various environmental conditions. Several applications of this device are presented to illustrate its versatility.

© 1967 Optical Society of America

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References

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  1. T. Morokuma, K. F. Neflen, T. R. Lawrence, T. M. Klucher, J. Opt. Soc. Am. 53, 394 (1963).
    [CrossRef]
  2. D. R. Herriott, J. Opt. Soc. Am. 56, 719 (1966).
    [CrossRef]
  3. A. Offner, Appl. Opt. 2, 153 (1963).
    [CrossRef]
  4. W. Weinstein, J. Sci. Instr. 28, 351 (1951).
    [CrossRef]
  5. W. L. Howes, D. R. Buchele, J. Opt. Soc. Am. 56, 1518 (1966).
    [CrossRef]
  6. J. Rancourt, R. R. Shannon, “Automated Processing of Interferometric Test Data”, paper presented at the annual meeting of the Optical Society of America, 21 Oct. 1966.
  7. G. W. Ritchey, Smithsonian Contributions to Knowledge (Smithsonian Institution, Washington, D. C., 1904).

1966 (2)

W. L. Howes, D. R. Buchele, J. Opt. Soc. Am. 56, 1518 (1966).
[CrossRef]

D. R. Herriott, J. Opt. Soc. Am. 56, 719 (1966).
[CrossRef]

1963 (2)

1951 (1)

W. Weinstein, J. Sci. Instr. 28, 351 (1951).
[CrossRef]

Buchele, D. R.

W. L. Howes, D. R. Buchele, J. Opt. Soc. Am. 56, 1518 (1966).
[CrossRef]

Herriott, D. R.

Howes, W. L.

W. L. Howes, D. R. Buchele, J. Opt. Soc. Am. 56, 1518 (1966).
[CrossRef]

Klucher, T. M.

Lawrence, T. R.

Morokuma, T.

Neflen, K. F.

Offner, A.

Rancourt, J.

J. Rancourt, R. R. Shannon, “Automated Processing of Interferometric Test Data”, paper presented at the annual meeting of the Optical Society of America, 21 Oct. 1966.

Ritchey, G. W.

G. W. Ritchey, Smithsonian Contributions to Knowledge (Smithsonian Institution, Washington, D. C., 1904).

Shannon, R. R.

J. Rancourt, R. R. Shannon, “Automated Processing of Interferometric Test Data”, paper presented at the annual meeting of the Optical Society of America, 21 Oct. 1966.

Weinstein, W.

W. Weinstein, J. Sci. Instr. 28, 351 (1951).
[CrossRef]

Appl. Opt. (1)

J. Opt. Soc. Am. (3)

J. Sci. Instr. (1)

W. Weinstein, J. Sci. Instr. 28, 351 (1951).
[CrossRef]

Other (2)

J. Rancourt, R. R. Shannon, “Automated Processing of Interferometric Test Data”, paper presented at the annual meeting of the Optical Society of America, 21 Oct. 1966.

G. W. Ritchey, Smithsonian Contributions to Knowledge (Smithsonian Institution, Washington, D. C., 1904).

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Figures (14)

Fig. 1
Fig. 1

Simple unequal path interferometer for testing large spherical surfaces.

Fig. 2
Fig. 2

Near-field diffraction resulting from dust particle contamination of microscope objective and pellicle beam splitter.

Fig. 3
Fig. 3

Unequal path interferometer used with null lens for testing large aspheric surface.

Fig. 4
Fig. 4

Optical schematic of laser unequal path interferometer.

Fig. 5
Fig. 5

Optical path diagram of f/1.7 beam diverger lens.

Fig. 6
Fig. 6

Interferogram during fabrication of 116.8-cm diam spherical mirror of 210.2-cm radius at center of curvature.

Fig. 7
Fig. 7

Interferometer head.

Fig. 8
Fig. 8

Interferometer in use at center of curvature of spherical test mirror.

Fig. 9
Fig. 9

LUPI optical assembly.

Fig. 10
Fig. 10

Combination beam diverger and null lens unequal path interferometer.

Fig. 11
Fig. 11

Ritchey testing of a large optical flat.

Fig. 12
Fig. 12

Off-axis test of a lens on a nodal slide bench.

Fig. 13
Fig. 13

Corrector plate fabrication testing using unequal path interferometer and null lens.

Fig. 14
Fig. 14

Interferogram for 76.2-cm diam spherical shell of 203.2-cm radius at center of curvature. (a) Ideal support. (b) Three-point support.

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