Abstract

Combining conventional interferometry with digital modulation allows interferometric signals to be isolated based on their delay. This isolation capability can be exploited in two ways. First, it can improve measurement sensitivity by reducing contamination by spurious interference. Second, it allows multiple optical components to be measured using a single metrology system. Digitally enhanced interferometry employs a pseudorandom noise (PRN) code phase modulated onto the light source. Individual reflections are isolated based on their respective delays by demodulation with the PRN code with a matching delay. The properties of the PRN code determine the degree of isolation while preserving the full interferometric sensitivity determined by the optical wavelength. Analysis and simulation indicate that errors caused by spurious interference can be reduced by a factor inversely proportional to the PRN code length.

© 2007 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |

  1. N. Bobroff, Meas. Sci. Technol. 4, 907 (1993).
    [CrossRef]
  2. J. Y. Vinet, V. Brisson, S. Braccini, I. Ferrante, L. Pinard, F. Bondu, and E. Tournié, Phys. Rev. D 56, 6085 (1997).
    [CrossRef]
  3. O. P. Lay and S. Dubovitsky, Opt. Lett. 27, 797 (2002).
    [CrossRef]
  4. F. Zhao, R. Diaz, G. Kuan, N. Sigrist, and Y. Beregovski, Proc. SPIE 4852, 370 (2003).
    [CrossRef]
  5. R. L. Pickholtz, D. L. Schilling, and L. B. Milstein, IEEE Trans. Commun. 30, 5 (1982).
    [CrossRef]
  6. K. A. Strain, G. Müller, T. Delker, D. H. Reitze, D. B. Tanner, J. E. Mason, P. A. Willems, D. A. Shaddock, M. B. Gray, C. Mow-Lowry, and D. E. McClelland, Appl. Opt. 42, 1244 (2003).
    [CrossRef] [PubMed]
  7. H. S. Al-Raweshidy and D. G. Uttamchandani, Proc. SPIE 1314, 342 (1990).
    [CrossRef]
  8. A. D. Kersey, A. Dandridge, and M. A. Davis, Electron. Lett. 28, 351 (1992).
    [CrossRef]
  9. O. P. Lay, S. Dubovitsky, D. A. Shaddock, and B. Ware, Opt. Lett. 32, 2933 (2007).
    [CrossRef] [PubMed]
  10. T. Day, A. C. Nilsson, A. D. Farinas, E. K. Gustafson, C. D. Nabors, and R. L. Byer, Electron. Lett. 25, 810 (1989).
    [CrossRef]
  11. M. Tinto and J. W. Armstrong, Phys. Rev. D 59, 102003 (1999).
    [CrossRef]

2007 (1)

2003 (2)

2002 (1)

1999 (1)

M. Tinto and J. W. Armstrong, Phys. Rev. D 59, 102003 (1999).
[CrossRef]

1997 (1)

J. Y. Vinet, V. Brisson, S. Braccini, I. Ferrante, L. Pinard, F. Bondu, and E. Tournié, Phys. Rev. D 56, 6085 (1997).
[CrossRef]

1993 (1)

N. Bobroff, Meas. Sci. Technol. 4, 907 (1993).
[CrossRef]

1992 (1)

A. D. Kersey, A. Dandridge, and M. A. Davis, Electron. Lett. 28, 351 (1992).
[CrossRef]

1990 (1)

H. S. Al-Raweshidy and D. G. Uttamchandani, Proc. SPIE 1314, 342 (1990).
[CrossRef]

1989 (1)

T. Day, A. C. Nilsson, A. D. Farinas, E. K. Gustafson, C. D. Nabors, and R. L. Byer, Electron. Lett. 25, 810 (1989).
[CrossRef]

1982 (1)

R. L. Pickholtz, D. L. Schilling, and L. B. Milstein, IEEE Trans. Commun. 30, 5 (1982).
[CrossRef]

Appl. Opt. (1)

Electron. Lett. (2)

A. D. Kersey, A. Dandridge, and M. A. Davis, Electron. Lett. 28, 351 (1992).
[CrossRef]

T. Day, A. C. Nilsson, A. D. Farinas, E. K. Gustafson, C. D. Nabors, and R. L. Byer, Electron. Lett. 25, 810 (1989).
[CrossRef]

IEEE Trans. Commun. (1)

R. L. Pickholtz, D. L. Schilling, and L. B. Milstein, IEEE Trans. Commun. 30, 5 (1982).
[CrossRef]

Meas. Sci. Technol. (1)

N. Bobroff, Meas. Sci. Technol. 4, 907 (1993).
[CrossRef]

Opt. Lett. (2)

Phys. Rev. D (2)

M. Tinto and J. W. Armstrong, Phys. Rev. D 59, 102003 (1999).
[CrossRef]

J. Y. Vinet, V. Brisson, S. Braccini, I. Ferrante, L. Pinard, F. Bondu, and E. Tournié, Phys. Rev. D 56, 6085 (1997).
[CrossRef]

Proc. SPIE (2)

F. Zhao, R. Diaz, G. Kuan, N. Sigrist, and Y. Beregovski, Proc. SPIE 4852, 370 (2003).
[CrossRef]

H. S. Al-Raweshidy and D. G. Uttamchandani, Proc. SPIE 1314, 342 (1990).
[CrossRef]

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 (2)

Fig. 1
Fig. 1

Digitally enhanced heterodyne interferometer for monitoring the separation of mirrors M1, M2, and M3. Reflections from the different mirrors are isolated by matching the decoding delays to the optical delays. EOM, electro-optic modulator; AOM, acousto-optic modulator; PRN, pseudorandom noise.

Fig. 2
Fig. 2

Simulated root power spectral densities of the configuration depicted in Fig. 1 for (a) the photodetector output and (b) contributions of each reflection to the c ( t τ 1 ) decoded output, V M 1 .

Equations (7)

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

E ̃ P = E 1 e i ϕ 1 c ( t τ 1 ) + E 2 e i ϕ 2 c ( t τ 2 ) + E 3 e i ϕ 3 c ( t τ 3 ) ,
E ̃ L O = e i ( 2 π f h t + ϕ L O ) .
V d ( t ) = E 1 cos ( ϕ 1 2 π f h t ϕ L O ) c ( t τ 1 ) + E 2 cos ( ϕ 2 2 π f h t ϕ L O ) c ( t τ 2 ) + E 3 cos ( ϕ 3 2 π f h t ϕ L O ) c ( t τ 3 ) .
V M 1 ( t ) = E 1 cos ( ϕ 1 2 π f h t ϕ L O ) + E 2 cos ( ϕ 2 2 π f h t ϕ L O ) c ( t τ 2 ) c ( t τ 1 ) + E 3 cos ( ϕ 3 2 π f h t ϕ L O ) c ( t τ 3 ) c ( t τ 1 ) .
Φ ( V M 1 ) Φ ( V M 2 ) = ϕ 1 ϕ 2 + ϵ 1 ϵ 2 ,
ϵ E 2 n E 1 rad.
δ L = δ ν ν L .

Metrics