title: Simple and sensitive technique for alignment of the pinhole of a spatial filter of a high-energy, high-power laser system.
abstract: In this paper, a new method for alignment of the pinhole of a spatial filter (SF) has been proposed and demonstrated experimentally. The effect of the misalignment of the pinhole on the laser beam profiles has been calculated for circular and elliptical Gaussian laser beams. Theoretical computation has been carried out to illustrate the effect of an intensity mask, placed before the focusing lens of the SF, on the spatial beam profile after the pinhole of the SF. It is shown, both theoretically and experimentally, that a simple intensity mask, consisting of a black dot, can be used to visually align the pinhole with a high accuracy of 5% of the pinhole diameter. The accuracy may be further improved using a computer-based image processing algorithm. Finally, the proposed technique has been demonstrated to align a vacuum SF of a compact 40 J Nd:phosphate glass laser system.
authors.affiliation: Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore, India. aksharma@rrcat.gov.in
authors.forename: Avnish Kumar
authors.initials: AK
authors.lastname: Sharma
authors.forename: Rajesh Kumar
authors.initials: RK
authors.lastname: Patidar
authors.forename: Deepak
authors.initials: D
authors.lastname: Daiya
authors.forename: Anandverdhan
authors.initials: A
authors.lastname: Joshi
authors.forename: Prasad Anant
authors.initials: PA
authors.lastname: Naik
authors.forename: Parshotam Dass
authors.initials: PD
authors.lastname: Gupta