Reducing Refractive Index Variations in Compression Molded Lenses by Annealing

Bo Tao, Lianguan Shen, Allen Yi, Mujun Li, Jian Zhou

Department of Integrated Systems Engineering, the Ohio State University, Columbus, Ohio, USA.
Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui, China.

DOI: 10.4236/opj.2013.32B029                

Abstract

Compression molding of glass optics is gradually becoming a viable fabrication technique for high precision optical lenses. However, refractive index variation was observed in compression molded glass lenses, which would contribute to image quality degradation. In this research, annealing experiments were applied to control the refractive index variation in molded glass lenses. The refractive index variations pre and post annealing experiment in molded lenses were measured by an experiment setup based on Mach-Zehnder interferometer. The experimental results showed that the refractive index variation can be controlled providing that a proper cooling process is applied during cooling.

Keywords

Refractive Index; Mach-Zehnder Interferometer; Optical; Annealing; Compression Molding

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	R. O. Maschmeyer, C. A. Andrysick, T. W. Geyer, H. E. Meissner, C. J. Parker and L. M. Sanford, “Precision Molded-Glass Optics,” Applied Optics, Vol. 22, No. 16, 1983, pp. 2413-2415. doi:10.1364/AO.22.002413
[2]	A. Y. Yi and A. Jain, “Compression Molding of Aspherical Glass Lenses – A Combined Experimental and Numerical Analysis,” Journal of the American Ceramic Society, Vol. 88, No. 3, 2005, pp. 579-586. doi:10.1111/j.1551-2916.2005.00137.x
[3]	U. Fotheringham, A. Baltes, P. Fischer, P. Höhn, R. Jedamzik, C. Schenk, C. Stolz and G. Westenberger, “Refractive Index Drop Observed After Precision Molding of Optical Elements: A Quantitative Understanding Based on the Tool– Narayanaswamy –Moynihan model,” Journal of the American Ceramic Society, Vol. 91, No. 3, 2008, pp. 780-783.doi:10.1111/j.1551-2916.2007.02238.x
[4]	W. Zhao, Y. Chen, L. G. Shen and A. Y. Yi, “Investigation of the Refractive Index Distribution in Precision Compression Glass Molding by Use of 3D Tomography,” Measurement Science and Technology, Vol. 20, No. 5, 2009, p. 055109. doi:10.1088/0957-0233/20/5/055109
[5]	L. J. Su, Y. Chen, A. Y. Yi, F. Klocke and G. Pongs, “Refractive Index Variation in Compression Molding of Precision Glass Optical Components,” Applied Optics, Vol. 47 No. 10, 2008, pp. 1662-1667. doi:10.1364/AO.47.001662
[6]	J. Wolfe and R. Chipman, “Reducing Symmetric Polarization Aberrations in A Lens by Annealing,” Optics Express, Vol. 12, No. 15, 2004, pp. 3443-3451. doi:10.1364/OPEX.12.003443
[7]	H. R. Lillie and H. N. Ritland, “Fine Annealing of Optical Glass,” Journal of the American Ceramic Society, Vol. 37, No. 10, 1954, pp. 466-473. doi:10.1111/j.1151-2916.1954.tb13978.x
[8]	H. E. Hagy, “Fine Annealing of Optical Glass for Low Residual Stress and Refractive Index Homogeneity,” Applied Optics, Vol. 7, No. 5, 1968, pp. 833-835. doi:10.1364/AO.7.000833
[9]	N. M. Brandt, “Annealing of 517.645 Borosilicate Optical Glass: I, Refractive Index,” Journal of the American Ceramic Society, Vol. 34, No. 11, 1951, pp. 332-338. doi:10.1111/j.1151-2916.1951.tb13480.x
[10]	W. Zhao, Y. Chen, L. G. Shen and A. Y. Yi, “Refractive index and Dispersion Variation in Precision Optical Glass Molding by Computed Tomography,” Applied Optics, Vol. 48, No. 9, 2009, pp. 3588-3595. doi:10.1364/AO.48.003588
[11]	Schott Glass Inc., Products and Applications, www. schott. de
[12]	M. Takeda, H. Ina and S. Kobayashi, “Fourier- Transform Method of Fringe-Pattern Analysis for Computer-Based Topography and Interferometry,” Journal of the Optical Society of America, Vol. 72, No. 1, 1982, pp. 156-160. doi:10.1364/JOSA.72.000156
[13]	D. C. Ghiglia and L. A. Romero, “Robust Two-Dimensional Weighted and Unweighted Phase Unwrapping That Uses Fast Transforms and Iterative Methods,” Journal of the Optical Society of America, Vol. 11, No. 1, 1994, pp. 107-117. doi:10.1364/JOSAA.11.000107
[14]	G. T. Herman, “Fundamentals of Computerized Tomography: Image Reconstruction from Projections,” Springer, London 2009. doi:10.1007/978-1-84628-723-7
[15]	H. N. Ritland, “Relation between Refractive Index and Density of A Glass at Constant Temperature,” Journal of the American Ceramic Society, Vol. 38, No. 2, 1955, pp. 86-88. doi:10.1111/j.1151-2916.1955.tb14581.x
[16]	L. J. Su and A. Y. Yi, “Investigation of the Effect of Coefficient of Thermal Expansion on Prediction of Refractive Index of Thermally Formed Glass Lenses Using FEM Simulation,” Journal of Non-Crystalline Solids, Vol. 357, No. 15, 2011, pp. 3006-3012. doi:10.1016/j.jnoncrysol.2011.04.005
[17]	Anton, A. Errapart, H. Aben and L. Ainola, “A Discrete Algorithm of Integrated Photoelasticity for Axisymmetric Problems,” Experimental Mechanics, Vol. 48, No. 5, 2008, pp. 613-620. doi:10.1007/s11340-008-9121-9
[18]	A. Errapart, H. Aben, L. Ainola and J. Anton, “Photoelastic Tomography for the Measurement of Thermal and Residual Stresses in Glass,” 9th International Congress on Thermal Stresses, Budapest, Hungary, 2011.
[19]	H. Aben and A. Errapart, “A Non-Linear Algorithm of Photoelastic Tomography for the Axisymmetric Problem,” Experimental Mechanics, Vol. 47, No. 6, 2007, pp. 821-830. doi:10.1007/s11340-007-9057-5