On-instrument wavefront sensor design for the TMT infrared imaging spectrograph (IRIS) update

Abstract

The first light instrument on the Thirty Meter Telescope (TMT) project will be the InfraRed Imaging Spectrograph (lRIS). lRlS will be mounted on a bottom port of the faci lity AO instrument NFIRAOS. IRIS will report guiding information to the NFlRAOS through the On-lnstrument Wavefront Sensor (OlWFS) that is part of IR1 S. This will be in a self-contained compartment of JRJS and will provide three deployable wavefront sensor probe arms. This entire unit wi ll be rotated to provide field de-rotation. Currently in our preliminary design stage our efforts have included: prototyping of the probe arm to determine the accuracy of this critical component, handling cart design and reviewing different types of glass for the atmospheric dispersion.

The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview

“…The probe arm, shown in Figure 4 under test, successfully met all requirements both at laboratory and -30 C temperatures. For an in depth description of the OIWFS see Dunn et al 4 . Figure 4: Testing of the prototype low order wavefront sensor probe arm at the Herzberg Institute of Astrophysics…”

“…The probe arm, shown in Figure 4 under test, successfully met all requirements both at laboratory and -30 C temperatures. For an in depth description of the OIWFS see Dunn et al 4 .…”

“…The InfraRed Imaging Spectrograph (IRIS, Larkin et al 1 ) is being developed as a first light, facility instrument for the Thirty Meter Telescope (TMT, Sanders et al 2 ) being constructed on the summit of Mauna Kea in Hawaii. IRIS utilizes the advanced adaptive optics system NFIRAOS (Herriot et al 3 ) and has integrated on-instrument wavefront sensors (OIWFS, Dunn et al 4 ) to achieve diffraction limited resolutions at wavelengths longer than 1 µm. IRIS combines a powerful "wide field" imager and an integral field spectrograph both covering wavelengths from 0.84 µm to 2.4 µm.…”

The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview

“…IRIS combines a "wide field" imager 3,4 and an integral field spectrograph 5,6 both covering wavelengths from 0.84 µm to 2.4 µm. Three on-instrument wavefront sensors (OIWFS) 7 have been developed and prototyped at National Research Council Herzberg (NRC-H) and serve to track tip-tilt and focus errors that the laser guide star system is blind to, and to properly compensate low-order modes of field distortion using the multi-conjugate AO system . Both science channels are built around the latest 4K by 4K HgCdTe detectors 8 (H4RG-10 for the imager, H4RG-15 for the spectrograph) from Teledyne.…”

The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview

“…IRIS combines a "wide field" imager 3,4 and an integral field spectrograph 5,6 both covering wavelengths from 0.84 µm to 2.4 µm. Three on-instrument wavefront sensors (OIWFS) 7 have been developed and prototyped at National Research Council Herzberg (NRC-H) and serve to track tip-tilt and focus errors that the laser guide star system is blind to, and to properly compensate low-order modes of field distortion using the multi-conjugate AO system . Both science channels are built around the latest 4K by 4K HgCdTe detectors [8][9][10] for the imager, H4RG-15 for the spectrograph) from Teledyne.…”