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Proceedings Paper • Open Access

Demonstration of the evolution of spectral resolving power as a superposition of higher order delayed beams

Paper Abstract

Introductory textbooks on basic optics introduce gratings and Fabry- Perot spectrometers separately with the logic that they are based on (i) diffraction and interference or (ii) division of wavefront and division of amplitude. Since in modern classrooms, most of the experiments can be carried out with highly coherent and collimated laser beams, we propose to introduce that gratings and Fabry-Perots are equivalent to each other by using a 'pencil' He-Ne beam illuminating a plane-parallel Fabry-Perot at an angle. It produces a set of distinct and parallel pencil of beams by multiple reflection resembling a multiple slit illumination. When these beams are superposed by a focusing lens, a multiple slit diffraction grating like pattern is observed. One can use an appropriately spaced etalon and reflectivity to demonstrate the evolution of resolving power by allowing step-by-step an increasing number of beams to interfere at the focus and slowly resolve the longitudinal modes (or frequencies) of the He-Ne laser.

Paper Details

Date Published: 13 October 1995
PDF: 17 pages
Proc. SPIE 2525, 1995 International Conference on Education in Optics, (13 October 1995); doi: 10.1117/12.224025
Show Author Affiliations
Chandrasekhar Roychoudhuri, Univ. of Connecticut (United States)
Tariq Manzur, Univ. of Connecticut (United States)


Published in SPIE Proceedings Vol. 2525:
1995 International Conference on Education in Optics
M. J. Soileau, Editor(s)

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