David R. Andersen
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View article: A Partial Near-infrared Guide Star Catalog for Thirty Meter Telescope Operations
A Partial Near-infrared Guide Star Catalog for Thirty Meter Telescope Operations Open
At first light, the Thirty Meter Telescope (TMT) near-infrared (NIR) instruments will be fed by a multiconjugate adaptive optics instrument known as the Narrow Field Infrared Adaptive Optics System (NFIRAOS). NFIRAOS will use six laser gui…
View article: Pushing the limits of near-infrared photometry with the Gemini Multi-Conjugate Adaptive Optics System: study of crowded fields in the globular cluster M5
Pushing the limits of near-infrared photometry with the Gemini Multi-Conjugate Adaptive Optics System: study of crowded fields in the globular cluster M5 Open
We present the deepest J −Ks near-infrared photometry of the globular cluster M5 (NGC 5904) from observations taken with the Gemini South Adaptive Optics Imager in tandem with the Gemini Multi-conjugate adaptive optics System (GeMS) on the…
View article: TMT AO Facility Status Report
TMT AO Facility Status Report Open
The TMT first light AO facility consists of the Narrow Field Infra-Red AO System (NFIRAOS), the associated Laser Guide Star Facility (LGSF), and the AO Executive Software (AOESW). NFIRAOS is a 60 x 60 order laser guide star (LGS) multi-con…
View article: A low-cost, high-speed, very high-order Shack-Hartmann sensor for testing TMT deformable mirrors
A low-cost, high-speed, very high-order Shack-Hartmann sensor for testing TMT deformable mirrors Open
The Thirty Meter Telescope will use a sophisticated adaptive optics system called NFIRAOS. This system utilizes two deformable mirrors conjugate to 0 km and 11.2 km to apply a Multi-Conjugate Adaptive Optics (MCAO) correction over a 2 arcm…
View article: Analyzing the AO operational behavior of non-sidereal tracking on the Thirty Meter Telescope using SysML
Analyzing the AO operational behavior of non-sidereal tracking on the Thirty Meter Telescope using SysML Open
We have modeled the functional and physical architecture, behavior, requirements, and parametric relationships through system-level simulation of observation workflows, using OMG\'s Systems Modeling Language (SysML), to validate use-case s…
View article: Design and development of WFOS, the Wide-Field Optical Spectrograph for the Thirty Meter Telescope
Design and development of WFOS, the Wide-Field Optical Spectrograph for the Thirty Meter Telescope Open
We present the current design of WFOS, a wide-field UV/optical (0.31-1.0 mu m) imaging spectrograph planned for first-light on the TMT International Observatory 30 m telescope. WFOS is optimized for high sensitivity across the entire optic…
View article: Optimal Differential Astrometry for Multiconjugate Adaptive Optics. I. Astrometric Distortion Mapping using On-sky GeMS Observations of NGC 6723
Optimal Differential Astrometry for Multiconjugate Adaptive Optics. I. Astrometric Distortion Mapping using On-sky GeMS Observations of NGC 6723 Open
The Extremely Large Telescope and the Thirty Meter Telescope will use state of the art multiconjugate adaptive optics (MCAO) systems to obtain the full D 4 advantage that their apertures can provide. However, to reach the full astrometric …
View article: Third-order terahertz optical response of graphene in the presence of Rabi Oscillations
Third-order terahertz optical response of graphene in the presence of Rabi Oscillations Open
Graphene has been shown to exhibit a nonlinear response due to its unique band structure. In this paper, we study the terahertz (THz) response metallic armchair graphene nanoribbons, specifically current density and Rabi oscillations beyon…
View article: The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview
The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview Open
IRIS is a diffraction limited instrument designed for first light of the Thirty Meter Telescope (TMT). It combines a nearinfrared integral field spectrograph (lenslet array and mirror slicer) and a wide-field imager with platescales as sma…
View article: Fast modulation and dithering for the NFIRAOS pyramid wavefront sensor
Fast modulation and dithering for the NFIRAOS pyramid wavefront sensor Open
The Narrow Field InfraRed Adaptive Optics System (NFIRAOS) for the Thirty Meter Telescope (TMT) will use a natural guide star (NGS) Pyramid Wavefront Sensor (PWFS). A 32-mm diameter Fast Steering Mirror (FSM) is used to modulate the positi…
View article: The Canadian Roots of the TMT First Light Instruments NFIRAOS and IRIS
The Canadian Roots of the TMT First Light Instruments NFIRAOS and IRIS Open
The two most advanced instrument concepts for the Thirty Meter Telescope (TMT) work together and both have substantial Canadian participation: The Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the first-light facility Multi-Con…
View article: Terahertz continuum generation in the LCS (Lieb) lattice
Terahertz continuum generation in the LCS (Lieb) lattice Open
Rabi oscillations in two-level Dirac systems have been shown to alter the frequency content of the system’s nonlinear response. In particular, when considering Rabi oscillations in a quantum model beyond the semiclassical Boltzmann theory,…
View article: Geometric distortion calibration with photolithographic pinhole masks for high-precision astrometry
Geometric distortion calibration with photolithographic pinhole masks for high-precision astrometry Open
Adaptive optics (AO) systems deliver high-resolution images that may be ideal for precisely measuring positions of stars (i.e., astrometry) if the system has stable and well-calibrated geometric optical distortions. A calibration unit equi…
View article: Geometric Distortion Calibration with Photo-lithographic Pinhole Masks for High-Precision Astrometry
Geometric Distortion Calibration with Photo-lithographic Pinhole Masks for High-Precision Astrometry Open
Adaptive optics (AO) systems deliver high-resolution images that may be ideal for precisely measuring positions of stars (i.e. astrometry) if the system has stable and well-calibrated geometric optical distortions. A calibration unit, equi…
View article: Geometric Distortion Calibration with Photo-lithographic Pinhole Masks for High-Precision Astrometry
Geometric Distortion Calibration with Photo-lithographic Pinhole Masks for High-Precision Astrometry Open
Adaptive optics (AO) systems deliver high-resolution images that may be ideal for precisely measuring positions of stars (i.e. astrometry) if the system has stable and well-calibrated geometric optical distortions. A calibration unit, equi…
View article: Multiconjugate adaptive optics simulator for the Thirty Meter Telescope: design, implementation, and results
Multiconjugate adaptive optics simulator for the Thirty Meter Telescope: design, implementation, and results Open
We present a multi-conjugate adaptive optics (MCAO) system simulator bench, HeNOS (Herzberg NFIRAOS Optical Simulator). HeNOS is developed to validate the performance of the MCAO system for the Thirty Meter Telescope, as well as to demonst…
View article: Multi-Conjugate Adaptive Optics Simulator for the Thirty Meter\n Telescope: Design, Implementation, and Results
Multi-Conjugate Adaptive Optics Simulator for the Thirty Meter\n Telescope: Design, Implementation, and Results Open
We present a multi-conjugate adaptive optics (MCAO) system simulator bench,\nHeNOS (Herzberg NFIRAOS Optical Simulator). HeNOS is developed to validate the\nperformance of the MCAO system for the Thirty Meter Telescope, as well as to\ndemo…
View article: NFIRAOS adaptive optics for the Thirty Meter Telescope
NFIRAOS adaptive optics for the Thirty Meter Telescope Open
NFIRAOS (Narrow-Field InfraRed Adaptive Optics System) will be the first-light multi-conjugate adaptive optics system for the Thirty Meter Telescope (TMT). NFIRAOS houses all of its opto-mechanical sub-systems within an optics enclosure co…
View article: Gemini infrared multi-object spectrograph: instrument overview
Gemini infrared multi-object spectrograph: instrument overview Open
The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a powerful new instrument being built to facility-class standards for the Gemini telescope. It takes advantage of the latest developments in adaptive optics and integral field spect…
View article: Optomechanical design of TMT NFIRAOS Subsystems at INO
Optomechanical design of TMT NFIRAOS Subsystems at INO Open
The adaptive optics system for the Thirty Meter Telescope (TMT) is the Narrow-Field InfraRed Adaptive Optics System (NFIRAOS). Recently, INO has been involved in the optomechanical design of several subsystems of NFIRAOS, including the Ins…
View article: Current Status and Implementation of Pyramid Truth Wavefront Sensor on NFIRAOS Simulation Bench at NRC-Herzberg
Current Status and Implementation of Pyramid Truth Wavefront Sensor on NFIRAOS Simulation Bench at NRC-Herzberg Open
We describe the components and functions and report the recent upgrades/modifications of the HeNOS (Herzberg NFIRAOS Optical Simulator) bench, a NFIRAOS (Narrow Field InfraRed Adaptive Optics System) simulator bench at NRC-Herzberg.The rec…
View article: Third-Order Optical Response of Metallic Armchair Graphene Nanoribbons to an Elliptically-Polarized Terahertz Excitation Field
Third-Order Optical Response of Metallic Armchair Graphene Nanoribbons to an Elliptically-Polarized Terahertz Excitation Field Open
We present a theoretical description of the nonlinear response induced by an\nelliptically-polarized terahertz beam normally-incident on intrinsic and\nextrinsic metallic armchair graphene nanorib- bons. Our results show that using\na stra…
View article: Using the multi-object adaptive optics demonstrator RAVEN to observe metal-poor stars in and towards the Galactic Centre
Using the multi-object adaptive optics demonstrator RAVEN to observe metal-poor stars in and towards the Galactic Centre Open
The chemical abundances for five metal-poor stars in and towards the Galactic\nbulge have been determined from H-band infrared spectroscopy taken with the\nRAVEN multi-object adaptive optics science demonstrator and the IRCS\nspectrograph …
View article: Stellar photometry with multi conjugate adaptive optics
Stellar photometry with multi conjugate adaptive optics Open
We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stella…
View article: First-principles study of the terahertz third-order nonlinear response of metallic armchair graphene nanoribbons
First-principles study of the terahertz third-order nonlinear response of metallic armchair graphene nanoribbons Open
We compute the terahertz third-order nonlinear conductance of metallic\narmchair graphene nanoribbons using time-dependent perturbation theory.\nSignificant enhancement of the intrinsic third-order conductance over the\nresult for instrins…
View article: Quantum Size Effects in the Terahertz Nonlinear Response of Metallic Armchair Graphene Nanoribbons
Quantum Size Effects in the Terahertz Nonlinear Response of Metallic Armchair Graphene Nanoribbons Open
We use time dependent perturbation theory to study quantum size effects on\nthe terahertz nonlinear response of metallic graphene armchair nanoribbons of\nfinite length under an applied electric field. Our work shows that quantization\ndue…
View article: Multi time-step wavefront reconstruction for tomographic adaptive-optics systems
Multi time-step wavefront reconstruction for tomographic adaptive-optics systems Open
In tomographic adaptive-optics (AO) systems, errors due to tomographic wavefront reconstruction limit the performance and angular size of the scientific field of view (FoV), where AO correction is effective. We propose a multi time-step to…
View article: Mass distributions in disk galaxies
Mass distributions in disk galaxies Open
We present results on luminous and dark matter mass distributions in disk galaxies from the DiskMass Survey. As expected for normal disk galaxies, stars dominate the baryonic mass budget in the inner region of the disk; however, at about f…
View article: The DiskMass Survey. X. Radio synthesis imaging of spiral galaxies
The DiskMass Survey. X. Radio synthesis imaging of spiral galaxies Open
We present results from 21 cm radio synthesis imaging of 28 spiral galaxies from the DiskMass Survey obtained with the VLA, WSRT, and GMRT facilities. We detail the observations and data reduction procedures and present a brief analysis of…
View article: The DiskMass Survey
The DiskMass Survey Open
We present results from 21 cm radio synthesis imaging of 28 spiral galaxies from the DiskMass Survey obtained with the VLA, WSRT, and GMRT facilities. We detail the observations and data reduction procedures and present a brief analysis of…