Dual self-image technique for beam collimation



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Herrera Fernández, José María and Sánchez Brea, Luis Miguel and Torcal Milla, Francisco José and Morlanes Calvo, Tomás and Bernabeu Martínez, Eusebio (2016) Dual self-image technique for beam collimation. Journal of optics, 18 (7). ISSN 2040-8978

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Official URL: http://dx.doi.org/10.1088/2040-8978/18/7/075608


We propose an accurate technique for obtaining highly collimated beams, which also allows testing the collimation degree of a beam. It is based on comparing the period of two different self-images produced by a single diffraction grating. In this way, variations in the period of the diffraction grating do not affect to the measuring procedure. Self-images are acquired by two CMOS cameras and their periods are determined by fitting the variogram function of the self-images to a cosine function with polynomial envelopes. This way, loss of accuracy caused by imperfections of the measured self-images is avoided. As usual, collimation is obtained by displacing the collimation element with respect to the source along the optical axis. When the period of both self-images coincides, collimation is achieved. With this method neither a strict control of the period of the diffraction grating nor a transverse displacement, required in other techniques, are necessary. As an example, a LED considering paraxial approximation and point source illumination is collimated resulting a resolution in the divergence of the beam of σ φ = ± μrad.

Item Type:Article
Additional Information:

© 2016 IOP Publishing Ltd.
The authors thank to O J Casas for his valuable comments. This work has been supported by project DPI2011-27851 of the Ministerio de Economía y Competitividad of Spain and the SEGVAUTO-TRIES Tecnologías 2013 CM S2013/MIT-2713 program of the Comunidad de Madrid.

Uncontrolled Keywords:Talbot effect; Self-imaging; Collimation; Diffraction
Subjects:Sciences > Physics > Optics
ID Code:39228
Deposited On:30 Sep 2016 16:46
Last Modified:03 Oct 2016 07:36

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