Point Spread Function analysis, modeling, simulations and laboratory testing for TMT NFIRAOS

Abstract

This paper discusses four on-axis natural guide star adaptive optics (NGS AO) point spread function reconstruction (PSFR) algorithms developed and benchmarked on simulated and laboratory telemetry data.

Point spread function reconstruction simulations for laser guide star multi-conjugate adaptive optics on extremely large telescopes

“…Hence, for completeness, PSFR accuracy has been evaluated over 10 different realizations. Figure 3 displays PSFR accuracy (see [1] for a definition of the performance metrics) versus field. For the LE science PSF averaged over the 10 realizations of atmospheric turbulence, all performance metrics are below 8% in Z-band, below 5% in J-band, and below 2% in K-band.…”

“…Point spread function reconstruction (PSFR) has gained increased attention in the adaptive optics (AO) community with the design and construction of extremely large telescopes (ELTs) [1]- [8]. In this paper, laser guide star (LGS) multi-conjugate adaptive optics (MCAO) PSFR simulation results are presented for the Thirty Meter Telescope (TMT) first-light LGS MCAO system, NFIRAOS.…”

“…The long-exposure optical transfer function (OTF) (Fourier transform of the long-exposure PSF) is obtained as a product of four OTFs: generalized fitting OTF (standard fitting and projection error), aliasing OTF, de-noised actuator error OTF (HO and LO), and static aberration OTF. The actuator error based PSFR algorithm 1 in [1] is the algorithm of choice since it can naturally be configured for any AO mode (classical NGS AO, LGS AO, and MCAO). The following points are worth noting:…”

“…• It is desirable to up-sample the actuator influence functions to compute ,te a H in Eq. (2.4) of [1], so as to map the actuator grid onto a finer aperture-plane grid prior to the computation of the long-exposure optical transfer function (OTF) from the actuator error and actuator noise covariance matrices. Up-sampling by a factor of 2 appears to be sufficient.…”

“…• For LGS MCAO, the aliasing OTF, sca K in Eq. (2.3) of [1], is computed for guide stars at finite range. This filter is pre-computed using closed-loop simulations and is averaged over multiple turbulence realizations.…”