M. Wang, S. Thibault "A novel technique of optical interference to generate equispaced fringe pattern of concentric ring" Proc. of SPIE, 5875, art. no. 5870G, 2005
Abstract: With the upcoming of the next-generation large-capacity CDs and DVDs using a blue-violet laser, the track's pitch will continue to decrease. The conventional methods for pregrooves will have a technique challenge to meet tiny-pitch specs at low cost. In order to get an equispaced fringe pattern with concentric-ring structure by using optical interference lithography, a novel optical-interference method is proposed with the use of a plane wave plus a conical wave along the same optical-axis (Z) propagation. Based on the optical interference analysis with the two waves, plane and conical waves, the resulting intensity varies consinusoidally with the phase difference, as modulated by the optical path difference between the plane and conical waves. The constructive and destructive interference will occur in the interference light field, only depending on if in phase or out of phase for the two waves. The concentric-ring structure of equispaced fringe pattern can be produced, and the fringe period depends on the wavelength of the light beams and conical constant of the conical wavefront as well. The novel optical interference system has been modeled and simulated with a kind of Mach-Zender interferometer arrangement by commercial optical code. The optical simulation results are proved to have a good agreement with that as given by the theoretical analysis.
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