Estimation of the lateral mis-registrations of the GRAVITY+ adaptive optics system - Perturbative method with open-loop modal correlation and non-perturbative method with temporal correlation of closed-loop telemetry

Open Access

Table 2

Main variables used in Sects. 3.2 and 3.3.

Variable	Description
δ	2D lateral error of Cartesian coordinates (δ_x, δ_y) and polar coordinates (\|δ\|, $A$ $\[\mathscr{A}\]$ \|δ\|)
Δ	Size of a subaperture (40 accross the pupil diameter)
1/τ^WFS = 1 kHz	Frequency of the AO loop with τ^lat ≃ τ^DM ≃ τ^WFS ≃ τ^RTC, Eq. (39)
n^mod = 500	Number of controlled modes (GPAO baseline)
500	Number of frames in the telemetry batch (0.5 s)
υ₀	Wind speed of the frozen flow
θ₀	Orientation of the frozen flow
n^ph	The number of photons per subaperture
g^∫ = 0.5	Integral gain of the AO loop
g^cl	Sensitivity of the closed loop estimator, Eq. (36)
ธ = 0.5	Gain of the lateral error corrective loop, Eq. (42)
$C_{0}$ $\[\mathscr{C}_0\]$	Theoretical correlation curve, Eq. (24).
${\tilde{C}}^{t}$ $\[\tilde{\mathscr{C}}^{\mathrm{t}}\]$	Best fit curve of the temporal correlation, Eq. (39)
${\tilde{C}}^{2 D}$ $\[\tilde{\mathscr{C}}^{2 \mathrm{D}}\]$	Best 2D fit map of the correlation coefficients Eq. (41)

Notes. Excepted when stated otherwise, the values given in this table are kept constant through all the simulations and experiments.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.