*Article* **Local Correction of the Light Position Implemented on an FPGA Platform for a 6 Meter Telescope**

**Valentina Klochkova 1,2 , Julia Sheldakova 2,\* , Ilya Galaktionov <sup>2</sup> , Alexander Nikitin <sup>2</sup> , Alexis Kudryashov <sup>2</sup> , Vadim Belousov <sup>2</sup> and Alexey Rukosuev <sup>2</sup>**


**Abstract:** The low-frequency component of the distortions caused by both the atmospheric turbulence and the behavior of the telescope itself has been studied. A corrector for the position of the center of the star image has been developed and is being used in front of the high-resolution Echelle spectrograph on the 6 m telescope of the Special Astrophysical Observatory, Russian Academy of Sciences. To speed up the calculations and to increase the bandwidth, a laser beam angular stabilization system based on an FPGA platform is considered. The system consists of two tip-tilt mirrors and two quadrant photodiodes. The FPGA analyzes the signals from the photodiodes, calculates and then applies the voltages to the piezo-driven tip-tilt mirrors to minimize the displacement of the beam on the photodiodes. The stabilization system was developed as a part of the adaptive optical system to improve the efficiency of the high-resolution Echelle spectrograph.

**Keywords:** tip-tilt mirror; FPGA; adaptive optics; angular stabilization system

**Citation:** Klochkova, V.; Sheldakova, J.; Galaktionov, I.; Nikitin, A.; Kudryashov, A.; Belousov, V.; Rukosuev, A. Local Correction of the Light Position Implemented on an FPGA Platform for a 6 Meter Telescope. *Photonics* **2022**, *9*, 322. https://doi.org/10.3390/photonics 9050322

Received: 15 March 2022 Accepted: 6 May 2022 Published: 8 May 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
