The optical calibration system for the CTAO-North Large Sized Telescope

M. Iori 1,a ,F. Ferrarotto a, L. Recchia a, F. Di Pierro b, C. Vigorito b a INFN Sezione di Roma1, 1 Università di Roma La Sapienza Rome Italy b INFN Sezione di Torino Italy Within 2026 CTAO will complete the construction and installation of all four Large-Sized Telescopes (LST-1-4) foreseen at Observatorio de Roque de Los Muchachos (ORM) in La Palma (Canary Island) and we will finish to equip all with the optical calibration system (Calibox). The LST cameras require a precise and regular calibration, consistent for all four telescopes. The CaliBoxes are designed to fulfill the requirements needed for the calibration of the cameras, including the monitor of the photon flux to guarantee the quality of the system for laser stability, uniform illumination and intensity range. We present in detail the electronics dedicated to the monitoring of the photon flux sent to the camera and the control of its stability.