On-Orbit Commissioning Phase Space Telescope Alignment Using Blind Scanning Search

Abstract

Astronomical telescopes are subject to multiple environmental factors resulting in the misalignment of optics, affecting their ability to efficiently collect starlight flux or resolve targets. These misalignments, such as the primary (M1) mirror relative positioning, can degrade image quality and may be insufficient to correct using typical alignment techniques in the initial phase of commissioning. In systems with severe misalignment, star images on the detector plane may be comparable to or even larger than the detector size. To address these challenges, a novel star-field Blind Scanning alignment technique is proposed to achieve first-order commissioning and compensate for initial misalignment without requiring additional calibration hardware.Blind Scanning simulates a three-mirror anastigmat (TMA) telescope by sweeping the primary mirror in x, y, and z according to a preset motion while recording only total photon flux. Flux‐trend statistics then drive a first‐order alignment and smoothly hand off to the fine alignment stage without ever measuring wavefront error. The method is validated first with Monte Carlo runs using a simplified defocus model to characterize detection performance across multiple misalignment cases, and then in a non-sequential Zemax model, where ZOS-API–automated displacement sweeps capture flux on both a single chip (narrow field of view) and a wide chip (full field of view). Mapping photon counts over twelve perturbations yields a three-dimensional flux landscape that shrinks gross misalignment from 20 mm to roughly 5 mm from nominal translation errors on a 3-meter-class primary observatory. Finally, stochastic parallel gradient descent (SPGD) and phase retrieval refine the point spread function to diffraction-limited quality. The approach mitigates the effects of extreme misalignment before finer alignment algorithms are applied, ultimately providing a cost-effective solution under dynamic environments.