Automated collimation testing in Lau interferometry using phase shifting technique

Rana, Santosh; Prakash, Shashi; Prakash, Sadguru

doi:10.1016/j.optlaseng.2009.01.004

Cited by 11 publications

(2 citation statements)

References 27 publications

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“…Also, double grating systems have been successfully employed in wavefront sensing and beam aberration measurements [7][8][9][10][11][12]. Related to these applications, collimation testing appears as a useful application of double grating systems [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Collimation method using a double grating system

et al. 2010

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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.

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Section: Introductionmentioning

confidence: 99%

Collimation method using a double grating system

et al. 2010

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“…Alternative approaches for testing of beam collimation are being explored worldwide. These approaches are mainly based on use of Moiré [9,10], Talbot [11][12][13][14] and interferometers [15][16][17], as well as other optical techniques [18][19][20][21]. Few of these systems are cost effective, as generally only two gratings are required but physical separation and alignment accuracy play important roles in such configurations.…”

Section: Introductionmentioning

confidence: 99%

High contrast laser beam collimation testing using two proximately placed holographic optical elements

Rajkumar

Dubey

Debnath

et al. 2018

J. Opt.

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Accuracy in laser beam collimation is very important in systems used for precision measurements. The present work reports a technique for collimation testing of laser beams using two proximately placed holographic optical elements (HOEs). The required HOEs are designed and fabricated such that upon illumination with the test beam, they release two laterally sheared wavefronts, at desired angles from the directly transmitted beam, that superimpose each other to generate straight interference fringes. Deviation from the collimation of the test beam results in orientation of these otherwise horizontal fringes. The novelty of this setup comes from the fact that HOEs are lightweight, as well as easy to fabricate as compared to conventional wedge plates used for collimation testing, and generate high contrast fringes compared to other interferometry, holography, Talbot and Moiré based techniques in a compact manner. The proposed technique is experimentally validated by measuring the orientation of fringes by an angle of 16.4° when a collimating lens of focal length 200 mm is defocused by 600 μm. The accuracy in the setting of this collimation position is obtained to be 10 μm.

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Collimation testing using coherent gradient sensing

Dhanotia

Prakash

2011

Optics and Lasers in Engineering

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Automated collimation testing in Lau interferometry using phase shifting technique

Cited by 11 publications

References 27 publications

Collimation method using a double grating system

Collimation method using a double grating system

High contrast laser beam collimation testing using two proximately placed holographic optical elements

Collimation testing using coherent gradient sensing

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