Approximation of normalized point source sensitivity using power spectral density and slopes of wavefront aberration

Seo, Byoung-Joon; Nissly, Carl; Troy, Mitchell; Angeli, George Z.; Ford, Virginia G.; Stepp, Larry M.; Williams, Eric

doi:10.1364/ao.52.003910

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…One might regard this as a somewhat complicated process of estimating a PSSN since there are simpler approximate methods such as β approximation and Slope RMS approximation [8]. However, we find that none of these approximation methods is applicable for the complex M1 system.…”

Section: Introductionmentioning

confidence: 88%

“…With the computed PSD, one can use the β approximation [8] to estimate its PSSN. The β approximation is a PSSN approximation using the PSD and the β function, which is the spatial frequency-dependent sensitivity to PSSN.…”

Section: B High-order Residual Errormentioning

confidence: 99%

“…According to the β function [8], the spatial frequency aberration beyond 20 cycles∕m can be assumed as a white noise for the r o of 200 mm and the wavelength of 500 nm.…”

Section: Surface Roughnessmentioning

confidence: 99%

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Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes

et al. 2013

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We present a method which estimates the normalized point-source sensitivity (PSSN) of a segmented telescope when only information from a single segment surface is known. The estimation principle is based on a statistical approach with an assumption that all segment surfaces have the same power spectral density (PSD) as the given segment surface. As presented in this paper, the PSSN based on this statistical approach represents a worst-case scenario among statistical random realizations of telescopes when all segment surfaces have the same PSD. Therefore, this method, which we call the vendor table, is expected to be useful for individual segment specification such as the segment polishing specification. The specification based on the vendor table can be directly related to a science metric such as PSSN and provides the mirror vendors significant flexibility by specifying a single overall PSSN value for them to meet. We build a vendor table for the Thirty Meter Telescope (TMT) and test it using multiple mirror samples from various mirror vendors to prove its practical utility. Accordingly, TMT has a plan to adopt this vendor table for its M1 segment final mirror polishing requirement.

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Section: Introductionmentioning

confidence: 88%

Section: B High-order Residual Errormentioning

confidence: 99%

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Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes

et al. 2013

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Static and dynamic disturbance compensation for optical misalignment of large ground-based wide field survey telescope

et al. 2022

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For large ground-based telescopes, static and dynamic disturbances would greatly degrade the optical performance. This is especially true for wide field survey telescopes with prime focus optics. The estimation of disturbance effects on large telescopes is becoming increasingly important during the design phase. Therefore, a wide field survey telescope with 2.5 m aperture and 3.5 deg field of view is studied in this research. This telescope is under construction now, and its first light is expected at the beginning of 2023. The estimation method for the optical performance under static and dynamic disturbances in the temporal domain and the active compensation method to improve the optical alignment, are investigated, which is a supplement for the simulation in the frequency domain. First, based on the mechanical model, the optical misalignment is established, where the deviation of the primary mirror is obtained from the length gauges and the deviation of the corrector is computed using the fitting method. Second, a method for compensating the static and dynamic disturbances is proposed, improving the optical performance. This method uses the disturbed primary mirror as the reference, and the corrector is actively controlled to align with it. Finally, a series of experimental tests and numerical simulations is conducted. The results show that the mechanical modeling error is within 10% and the maximum optical misalignment is reduced from 12 ′ ′ / 0.27 to 0.2 ′ ′ / 0.006 m m for static disturbance and from 1.3 ′ ′ / 0.03 to 0.4 ′ ′ / 0.01 m m for dynamic disturbance. Through active compensation, the telescope optical property is greatly improved. The modeling method and the simulation process mentioned in this research can also be used in the other relevant fields.

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Relay optical function and pre-construction results of a Giant Steerable Science Mirror for a thirty meter telescope

et al. 2019

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Approximation of normalized point source sensitivity using power spectral density and slopes of wavefront aberration

Cited by 3 publications

References 7 publications

Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes

Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes

Static and dynamic disturbance compensation for optical misalignment of large ground-based wide field survey telescope

Relay optical function and pre-construction results of a Giant Steerable Science Mirror for a thirty meter telescope

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