NFIRAOS, the Thirty Meter Telescope's first adaptive optics system is an order 60x60 Multi-Conjugate AO system with two deformable mirrors. Although most observing will use 6 laser guide stars, it also has an NGS-only mode. Uniquely, NFIRAOS is cooled to -30 °C to reduce thermal background. NFIRAOS delivers a 2-arcminute beam to three client instruments, and relies on up to three IR WFSs in each instrument. We present recent work including: robust automated acquisition on these IR WFSs; trade-off studies for a common-size of deformable mirror; real-time computing architectures; simplified designs for high-order NGS-mode wavefront sensing; modest upgrade concepts for highcontrast imaging.
NFIRAOS, the TMT Observatory's initial facility AO system is a multi-conjugate AO system feeding science light from 0.8 to 2.5 microns wavelength to several near-IR client instruments. NFIRAOS has two deformable mirrors optically conjugated to 0 and 11.2 km, and will correct atmospheric turbulence with 50 per cent sky coverage at the galactic pole. An important requirement is to have very low background: the plan is to cool the optics; and one DM is on a tip/tilt stage to reduce surface count. NFIRAOS' real time control uses multiple sodium laser wavefront sensors and up to three IR natural guide star tip/tilt and/or tip/tilt/focus sensors located within each client instrument. Extremely large telescopes are sensitive to errors due to the variability of the sodium layer. To reduce this sensitivity, NFIRAOS uses innovative algorithms coupled with Truth wavefront sensors to monitor a natural star at low bandwidth. It also includes an IR acquisition camera, and a high speed NGS WFS for operation without lasers. For calibration, NFIRAOS includes simulators of both natural stars at infinity and laser guide stars at varying range distance. Because astrometry is an important science programme for NFIRAOS, there is a precision pinhole mask deployable at the input focal plane. This mask is illuminated by a science wavelength and flat-field calibrator that shines light into NFIRAOS' entrance window. We report on recent effort especially including trade studies to reduce field distortion in the science path and to reduce cost and complexity.
NFIRAOS is a laser guide star multiconjugate adaptive optics system-a practical approach to providing diffraction limited image quality in the NIR over a 30" field of view, with high sky coverage. This will enable a wide range of TMT science that depends upon the large corrected field of view and high precision astrometry and photometry. We review recent progress developing the design and conducting performance estimates for NFIRAOS.
The Maunakea Spectroscopic Explorer (MSE) will each year obtain millions of spectra in the optical to nearinfrared, at low (R 3, 000) to high (R 40, 000) spectral resolution by observing >4,000 spectra per pointing via a highly multiplexed fiber-fed system. Key science programs for MSE include black hole reverberation mapping, stellar population analysis of faint galaxies at high redshift, and sub-km/s velocity accuracy for stellar astrophysics.One key metric of the success of MSE will be its survey speed, i.e. how many spectra of good signal-to-noise ratio will MSE be able to obtain every night and every year. The survey speed is directly linked to the allocation efficiency -how many fibers in the focal surface can be allocated to targets -and to the injection efficiencywhat fraction of light from a target can enter the fiber at the focal surface.In this paper we focus on the injection efficiency and how to optimize it to increase the signal-to-noise ratio of targets observed in sky dominated conditions. The injection efficiency depends on the size of the fiber and requires highly precise, repeatable and stable positioning of the fiber in the focal surface. We present the allocation budget used for Conceptual Design Review and the modeling that allows to estimate the injection efficiency, which is just one part necessary to meet the science requirements on sensitivities.
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