Abstract: This study aims to improve the integrated testing of large-aperture telescopes to clarify the fundamental principles of an integrated testing system based on astrophotonics. Our demonstration and analyses focused on element-position sensing and modulation based on spatial near-geometric beams, high-throughput step-difference measurements based on channel spectroscopy, distributed broadband-transmittance testing, and standard spectral tests based on near-field energy regulation. Comprehensive analyses and experiments were conducted to confirm the feasibility of the proposed system in the integrated testing process of large-aperture telescopes. The results demonstrated that the angular resolution of the light rays exceeded 5 arcsec, which satisfies the requirements for component-position detection in future large-aperture telescopes. The measurement resolution of the wavefront tilt was better than 0.45 µrad. Based on the channel spectral method—which combined a high signal-to-noise ratio and high sensitivity, along with continuous-spectral digital segmentation and narrowband-spectral physical segmentation—a resolution of 0.050 μm and a range of 50 μm were obtained. After calibration, the measurement resolution of the pupil deviation improved to exceed 4% accuracy, and the transmission measurements achieved a consistency of over 2% accuracy. Regarding fringe-broadband interferometry measurements, the system maintained high stability, ensuring its operation within the coherence length, and robustly detected the energy without unwrapping the phase. The use of a projector for calibrating broadband-spectrum measurements led to a reduction in contrast from 0.8142 to 0.6038, which further validates the system's applicability in the integrated testing process of large-aperture telescopes. This study greatly enhanced the observational capabilities of large-aperture telescopes while reducing the integrated system's volume, weight, and power consumption.
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