Abstract

The Lloyd moiré interferometer was introduced in Appl. Opt. 6, 1707 ( 1967), as a means of testing interferometrically a path across very large surfaces in oblique to grazing incidence. The width of the path is determined by the optics in use. For any sensible angle of incidence, the Lloyd interference fringes will be very narrowly spaced, but they are transformed into conveniently visible fringes by a moiré grating. The precision of the Lloyd moiré interferometer is limited by the very large angle of incidence and by the relatively poor definition of the moiré fringes. The objective of the present paper is to show an improved Lloyd interferometer technique, which with equally simple instrumentation permits one to vary and increase the sensitivity in testing large surfaces in oblique incidence by decreasing the angle of incidence.

© 1970 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. P. Langenbeck, Appl. Opt. 6, 1707 (1967).
    [CrossRef] [PubMed]
  2. A. Lohmann, O. Bryndahl, Appl. Opt. 6, 1934 (1967).
    [CrossRef] [PubMed]
  3. G. Scherf, Jena Rev. 2, 107 (1966).

1967

1966

G. Scherf, Jena Rev. 2, 107 (1966).

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)

Fig. 1
Fig. 1

Higher-order Lloyd interferometer: Q, light source; Q, its mirror image; T, test surface; G, diffraction grating; q, series of diffraction images of Q; q, series of diffraction images of Q; G, image plane.

Fig. 2
Fig. 2

(a) Lloyd moiré interferogram of 18-cm diam, nominally flat mirror, recorded as described in Ref. 1. A Fizeau multiple-beam interferogram of this mirror is shown in Fig. 5(a). (b) Diffraction pattern in the focal plane of objective O placed behind G (see Fig. 1). (c) Same as in (b), but after slightly rotating of the grating.

Fig. 3
Fig. 3

(a) (+1, −1) Lloyd interferogram. (b) Associated diffraction pattern.

Fig. 4
Fig. 4

(a) (+2, −2) Lloyd interferogram. (b) Associated diffraction pattern.

Fig. 5
Fig. 5

Comparison between higher order Lloyd, (a), (c) and Fizeau multiple beam interferogram (b), (d) of a nominally flat mirror in two different stages of finishing.

Equations (3)

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

2 = N λ / g = 2 ( 90 ° α ) .
h = ± ( λ / [ 2 sin ( N λ / 2 g ) ] ) ( Δ P / P ) ,
h = ± ( g / N ) ( Δ P / P ) ,

Metrics