The interpretation of online measurements of optical fibre diameter

Abstract

The requirements for optical fibre diameter measurement for feedback control during drawing and for quality assurance in precision applications are different. The signal from a 1000-Hz scanning laser gauge measuring 125-mm nominal diameter fibre was examined to see if this instrument could service both applications. Static measurements showed that sensor noise was largely unaffected by the measurement position of the fibre, the sampling rate or external electrical/acoustic noise. In each case the sensor noise was essentially normally distributed with a standard deviation of 0.13 mm. Offline fibre measurements (using a video grey-scale analyser) showed significant diameter variations on a 40-mm length scale. The distribution of this diameter variation was consistent with that from the online laser gauge. It was concluded that the current default option (scanning at 1000 Hz and using window-based averaging to give an effective sampling rate of 8 Hz) is adequate if the objective is to ensure a nominal average diameter on a long-length scale via feedback control. However, such an approach will prove inadequate for quality assurance in emerging precision applications. The latter objective will require a combination of a faster scanning rate with more sophisticated signal filtering to provide a means for monitoring short-scale diameter variations while simultaneously providing a signal for use by a controller more responsive than simple feedback. Such monitoring is also a necessary prerequisite for quantifying the extent of flow instabilities in the vicinity of the drawing fibre as a function of furnace design.

Keywords

diameter control fibre drawing fibre fabrication laser-based monitoring signal filtering silica optical fibre

Get full access to this article

View all access options for this article.

References

Bozic, S. M. 1979: Digital and Kalman filtering: an introduction to discrete-time filtering and optimum linear estimation. London: E. Arnold.

Brehm, C. , Mercereau, O. , Lipinski, G. and Vailleau, G. P. 1994: In Day, G. W. , Franzen, D. L. and Hickernell, R. K. , editors. NIST Symposium on Optical fiber measurements. Boulder, CO: NIST 133-136.

Choudhury, S. R. and Jaluria, Y. 1998: Practical aspects in the drawing of an optical fiber. Journal of Materials Research 13, 483-493.

Choudhury, S. R. , Jaluria, Y. and Lee, S. H. K. 1999: A computational method for generating the free-surface neck-down profile for glass flow in optical fiber drawing. Numerical Heat Transfer, Part A (Applications) 35, 1-24.

Cohen, L. G. and Glynn, P. 1973: Dynamic measurement of optical fibre diameter. Review of Scientific Instruments 44, 1749-1752.

Dianov, E. M. , Kashin, V. V. , Perminov, S. M. , Perminova, V. N. , Rusanov, S. Y. and Sysoev, V. K. 1988: The effect of different conditions on the drawing of fibers from preforms. Glass Technology 29, 258-262.

Forest, M. G. and Zhou, H. 2001: Unsteady analyses of thermal glass fibre drawing processes. European Journal of Applied Mathematics 12, 479-496.

Ibsen, M. and Laming, R. I. 1999: In OFC/IOOC’99. Optical Fiber Communication Conference and the International Conference on Integrated Optics and Optical Fiber Communications, Vol. 4, Piscataway, NJ, 2-4.

Law, S. , Barton, G. W. and Phan, T. N. 2004: In SPIE International Symposium on Smart Materials, Nano-, and Micro-Smart Systems, Vol. 5650. Sydney: S. P. I. E.

10.

Law, S. H. , Phan, T. N. , Barton, G. W. , Barton, M. J. and Elsey, J. 2002: In NIST Symposium on Fibre Measurements 2002, Technical Digest. Boulder, CO: NIST, 37-40.

11.

Law, S. H. , Phan, T. N. and Poladian, L. 2001: In Proceedings 51st Electronic Components and Technology Conference, Buena Vista, 1447-1450.

12.

Phan, T.N. 2003: The study of fibre diameter control and variation during the drawing process. PhD, Department of Chemical Engineering, University of Sydney, Sydney.

13.

Press, W. H. , Teukolsky, S. A. , Vetterling, W. T. and Flannery, B. P. 1992, In Numerical Recipes in C, Chapters 12 & 13. Cambridge: Cambridge University Press.

14.

Takeuchi, R. , Zhang, X. , Yoshikawa, T. and Takei, Y. 2004: Design of Chebyshev-type IIR filters with approximately linear phase characteristics. Electronics and Communications in Japan, Part III - Fundamental Electronic Science 87, 1-9.

15.

TIA/EIA-455-176. 1999: FOTP-176 - Method for measuring optical fibre cross-sectional geometry by automated grey-scale analysis. Telecommunications Industry Association.