Alignment procedure for off-axis-parabolic telescopes in the context of high-intensity laser beam transport

Abstract

Off-axis parabolic telescopes are rarely used in high-intensity, high-energy lasers, despite their favorable properties for beam transport such as achromatism, low aberrations and the ability to handle high peak intensities. One of the major reasons for this is the alignment procedure which is commonly viewed as complicated and time consuming. In this article, we revisit off-axis parabolic telescopes in the context of beam transport in high-intensity laser systems and present a corresponding analytical model. Based on that, we propose a suitable setup that enables fast and repeatable alignment for everyday operation.

A 100-PW compressor based on single-pass single-grating pair

“…This wavefront aberration can then be directly measured by a Shack–Hartmann sensor. Furthermore, by inducing an alignment light at the CCD position, this setup can also be used to precisely align the off-axis-parabolic BE system before the main compressor, which will improve the daily operation of the PW laser system [ 26 ] .…”

Ultra-compact post-compressor on-shot wavefront measurement for beam correction at PHELIX

“…In a previous work [ 18 ] , we presented an alignment scheme for OAP telescopes, based on the overlap of the focal spots of both OAPs using a back-propagating alignment beam. In the same work, we delivered straightforward estimation formulae for the alignment precision that can be expected and the WF defects that would be caused by the errors.…”

“…As we stated above in the list of requirements, the RMS of the transmitted WF should be below 0.052 . Obviously, the maximum transversal WF error, which primarily consists of astigmatism and coma [ 18 ] , easily fulfills this requirement. The maximum longitudinal error, on the other hand, stresses the given limit.…”

“…However, the alignment beam stayed in place afterwards for the alignment of the OAP telescope, using the alignment scheme described in our previous work [ 18 ] , where the intermediate focal spots of the main beam and the back-propagating alignment beam were overlapped spatially.…”

“…In a previous work [ 18 ] , we showed that telescopes based on off-axis parabolic mirrors (OAPs) represent a reliable and attractive solution for large-aperture systems as long as a suitable alignment setup is employed. As these optics are commercially available with small F -numbers and can, in principle, compose aberration-free telescopes, an OAP telescope is a viable solution for compact beam transport.…”