![]() The array can also be masked to reduce the field-of-view while enabling a mix of higher spectral resolutions and bandpasses. The Lenslet channel features an oversized array and meets full requirements over a sampling size of 100x100. ![]() The Lenslet channel of the spectrograph provides the finer sampling scales (4 & 9 mas) and probes the diffraction limit of the telescope. IRIS’s Integral Field Spectrograph provides users with two means of spatially sampling the field. * NOTE: The Lenslet channel of IRIS’s spectrograph is not shown. (readout and control electronics not shown). IRIS calibrations including wavelength and flat-fielding are provided by a separate system, the NFIRAOS Science Calibration Unit (NSCU), which mounts at the front of NFIRAOS and provides.ģ: Slicer Integral Field Unit (IFU) (NIAOT/Caltech).ĥ: Three mirror anastigmat (TMA) collimator.ġ0: H4RG – 15 µm detector. The electronics rack houses IRIS computers and controls, etc. The cable wrap serves as the relay between the instrument and IRIS electronics rack. Observatory services as well as IRIS data and mechanism control cables route primarily along the exterior of the science cryostat to IRIS’s cable wrap, which is located on the Nasmyth platform. The rotator is embedded within the IRIS support structure and provides the mechanical interface between the OIWFS/science cryostat and the support structure. NFIRAOS does not include a K-mirror, as such, IRIS also includes an instrument rotator to provide field de-rotation. IRIS benefits from occupying the bottom port and thus hangs beneath NFIRAOS providing IRIS with a gravity invariant environment. NFIRAOS itself can host up to three instruments, each “ported” to either its top, side or bottom. Both the OIWFS enclosure and science cryostat are supported by the IRIS support structure, which also provides the mechanical interface to NFIRAOS. The science cryostat mates to IRIS’s upper enclosure, which maintains the environmental interface to NFIRAOS and further hosts IRIS’s three on-instrument wavefront sensors (OIWFS) for natural guide star (NGS) Tip/Tilt/Focus (TTF) measurements. The imager and IFS are housed within the science cryostat, which provides the required vacuum cryogenic environment. Both the imager and IFS are built around 4Kx4K HgCdTe detectors from Teledyne. The Imager also contains an atmospheric dispersion corrector (ADC) and cold Lyot stop. Complementary to this, the IFS contains a range of gratings to offer spectral resolutions of at least 4,000 for all broad (20%) bandpasses as well as spectral resolutions of 8,000 made achievable through a combination of its filters, gratings and field masks. Given the sequential layout, the imager and IFS share a common suite of filters enabling science at a variety of narrow and broad bandpasses. The imager relays the on-axis portion of its field to the IFS, which affords users’ two “slicing” techniques and four selectable spaxel scales ranging from 4 mas/spaxel to 50 mas/spaxel with a minimum 3,960 spaxels available to users when operating in an un-masked configuration. The IRIS imager provides a “wide field” greater than 30 x 30 arcseconds with pixel sampling of 4 mas. To achieve diffraction limited performance, IRIS works in tandem with the facility adaptive optics (AO) instrument – NFIRAOS (Narrow Field InfraRed Adaptive Optics System). IRIS offers diffraction limited performance for wavelengths longer than 1 µm. ![]() IRIS is a modular instrument with a science channel including both an imager and an integral field spectrograph (IFS) and provides simultaneous wavelength coverage over the 0.84 µm – 2.4 µm range. The InfraRed Imaging Spectrograph (IRIS) is a “workhorse”, first light instrument for the Thirty Meter Telescope (TMT). Interim FDRs (April to June 2021) covered most subsystems - Defined the path toward completing technical design work. Status: Entered Final Design Stage November 2017. As such, the field is not contiguous.Īstrometry Accuracy: absolute astrometry 2 mas, differential astrometry 50 µas in a 100 s exposure with 10 µas systematics * Note: the imager field is comprised of a 2x2 mosaic of 4kx4k H4RG-10 detectors. Slicer 25mas: 1.125" x 2.200" (full Slicer IFU array 88 slices each 1x45 resolution elements) & 1.125" x 1.100" (half masked 50mas: 2.250" x 4.400" (full Slicer IFU array 88 slices each 1x45 resolution elements) & 2.250" x 2.200" (half masked IFU)įilters: Broadband filters (Y, Z, J, H, K), Narrowband (5 % bandpass) filters, and specialized filters (< 1% bandpass) * Note: All requirements are being met over a slightly smaller number of lenslets. Spectral resolution: R = 4,000 for all modes with broadband filters and select modes offering R = 8,000 and 10,000.
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