Collimation method using a double grating system.
We present a collimation technique based on a double grating system to locate with high accuracy an emitter in the focal plane of a lens. Talbot self-images are projected onto the second grating producing moiré interferences. By means of two photodetectors positioned just behind the second grating, it is possible to determine the optimal position of the light source for collimation by measuring the phase shift between the signals over the two photodetectors. We obtain mathematical expressions of the signal in terms of defocus. This allows us to perform an automated technique for collimation. In addition, a simple and accurate visual criterion for collimating a light source using a lens is proposed. Experimental results that corroborate the proposed technique are also presented.
Sanchez-Brea
Luis Miguel
LM
Universidad Complutense de Madrid, Applied Optics Complutense Group, Optics Department, Facultad de Ciencias Físicas, Ciudad Universitaria s.n., 28040, Madrid, Spain. sanchezbrea@fis.ucm.es
Torcal-Milla
Francisco Jose
FJ
Salgado-Remacha
Francisco Javier
FJ
Morlanes
Tomás
T
Jimenez-Castillo
Isidoro
I
Bernabeu
Eusebio
E