Abstract
In this paper, we propose a simple, fast, and accurate technique for detection of collimation position of an optical beam using the self-imaging phenomenon and correlation analysis. Herrera-Fernandez et al. [J. Opt. 18, 075608 (2016) [CrossRef] ] proposed an experimental arrangement for collimation testing by comparing the period of two different self-images produced by a single diffraction grating. Following their approach, we propose a testing procedure based on correlation coefficient (CC) for efficient detection of variation in the size and fringe width of the Talbot self-images and thereby the collimation position. When the beam is collimated, the physical properties of the self-images of the grating, such as its size and fringe width, do not vary from one Talbot plane to the other and are identical; the CC is maximum in such a situation. For the de-collimated position, the size and fringe width of the self-images vary, and correspondingly the CC decreases. Hence, the magnitude of CC is a measure of degree of collimation. Using the method, we could set the collimation position to a resolution of 1 μm, which relates to in terms of collimation angle (for testing a collimating lens of diameter 46 mm and focal length 300 mm). In contrast to most collimation techniques reported to date, the proposed technique does not require a translation/rotation of the grating, use of complicated phase evaluation algorithms, or an intricate method for determination of period of the grating or its self-images. The technique is fully automated and provides high resolution and precision.
© 2018 Optical Society of America
Full Article | PDF ArticleMore Like This
Shivangi Bande, Vimal Bhatia, and Shashi Prakash
Appl. Opt. 59(24) 7160-7168 (2020)
Shashi Prakash, Santosh Rana, Satya Prakash, and Osami Sasaki
Appl. Opt. 47(31) 5938-5943 (2008)
Jitendra Dhanotia and Shashi Prakash
Appl. Opt. 50(10) 1446-1452 (2011)