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Vibration measurements at the Gemini South observatory were conducted in February 2020, in order to experimentally determine acceleration transfer functions between the instrument support structure and key locations on the telescope, including the optics. An electrodynamic exciter was used to impart known dynamic forces into the telescope structure. Acceleration responses were measured at numerous locations on the telescope, including on M1 and M2, using the facility Vibration Monitoring System (VMS) accelerometers. This paper describes the equipment, the experimental approach, and will summarize initial results from these tests., Ground-based and Airborne Telescopes VIII, December 14-18, 2020, Online Only, United States, Series: Proceedings of SPIE

The Herzberg Astronomy and Astrophysics Research Centre has established a comprehensive and versatile vibration measurement capability. In recent years, HAA personnel have executed a number of diverse vibration measurement projects, including recent vibration transmission measurements at Gemini South. In this paper we describe the HAA’s vibration measurement capabilities, including the equipment and experimental approaches that have been used. We will provide some illustrative examples of recent applications and results, and highlight plans for further development of our capabilities., Ground-based and Airborne Telescopes VIII, December 14-18, 2020, Online Only, United States, Series: Proceedings of SPIE

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 instrument selection mirror (ISM), the beam splitter (NBS), and the source simulator system (NSS) comprising the focal plane mask (FPM), the laser guide star (LGS), and natural guide star (NGS) sources. This paper presents an overview of these subsystems and the optomechanical design approaches used to meet the optical performance requirements under environmental constraints., Optomechanical Engineering 2017, 9 - 10 August 2017, San Diego, California, United States

The Dish Verification Antenna 1 (DVA-1) is a 15m aperture offset Gregorian radio telescope featuring a rim-supported single piece molded composite primary reflector on an altitude-azimuth pedestal mount. Vibration measurements of the DVA-1 telescope were conducted over three days in October 2014 by NSI Herzberg engineers. The purpose of these tests was to measure the first several natural frequencies of the DVA-1 telescope. This paper describes the experimental approach, in particular the step-release method, and summarizes some interesting results, including unexpectedly high damping of the first mode over a narrow range of zenith angles.

The Narrow Field InfraRed Adaptive Optics System (NFIRAOS) will be the first-light facility Adaptive Optics (AO) system for the Thirty Meter Telescope (TMT). NFIRAOS will be able to host three science instruments that can take advantage of this high performance system. NRC Herzberg is leading the design effort for this critical TMT subsystem. As part of the final design phase of NFIRAOS, we have identified multiple subsystems to be sub-contracted to Canadian industry. The scope of work for each subcontract is guided by the NFIRAOS Work Breakdown Structure (WBS) and is divided into two phases: the completion of the final design and the fabrication, assembly and delivery of the final product. Integration of the subsystems at NRC will require a detailed understanding of the interfaces between the subsystems, and this work has begun by defining the interface physical characteristics, stability, local coordinate systems, and alignment features. In order to maintain our stringent performance requirements, the interface parameters for each subsystem are captured in multiple performance budgets, which allow a bottom-up error estimate. In this paper we discuss our approach for defining the interfaces in a consistent manner and present an example error budget that is influenced by multiple subsystems.

The early-light facility adaptive optics system for the Thirty Meter Telescope (TMT) is the Narrow-Field InfraRed Adaptive Optics System (NFIRAOS). The science beam splitter changer mechanism and the visible light beam splitter are subsystems of NFIRAOS. This paper presents the opto-mechanical design of the NFIRAOS beam splitters subsystems (NBS). In addition to the modal and the structural analyses, the beam splitters surface deformations are computed considering the environmental constraints during operation. Surface deformations are fit to Zernike polynomials using SigFit software. Rigid body motion as well as residual RMS and peak-to-valley surface deformations are calculated. Finally, deformed surfaces are exported to Zemax to evaluate the transmitted and reflected wave front error. The simulation results of this integrated opto-mechanical analysis have shown compliance with all optical requirements.

NFIRAOS is the first light adaptive optics system for the Thirty Meter Telescope (TMT). NFIRAOS components are maintained at a stable -30°C ±0.5°C by embedding an actively cooled refrigeration system in the walls of the NFIRAOS enclosure. Three instruments are attached to interface ports in the NFIRAOS enclosure and are required to be thermally stable while the instrument rotates in place. Additionally, instruments must be installed and removed while NFIRAOS is cold to avoid lengthy cool-down cycles. A portion of the actively cooled enclosure system and the interface has been prototyped at NRC-Herzberg. We present a description of the design of the interface and results of testing so far and lessons learned.

Radio telescopes striving for orders of magnitude more sensitivity in the cm-wave band require reflector antennas with high performance at low relative cost compared to conventional approaches. The Composite Applications for Radio Telescopes (CART) programme at the National Research Council's (NRC's) Dominion Radio Astrophysical Observatory, near Penticton Canada has been investigating ways to build such telescopes since 2005. In 2010 a collaboration between NRC and the US-Technology Development Project (US TDP) was formed to develop a prototype 15m Gregorian offset antenna for the Square Kilometre Array (SKA). The telescope uses NRC's composite carbon fibre reflector technology to implement the highly optimized shaped optics design and innovative mechanical concepts developed by the US TDP. The result is Dish Verification Antenna-1 (DVA1), a next generation antenna that has exceptional sensitivity (> 9 m2/K), with low monotonically decreasing far out sidelobes (< −50 dB), and high stability over environmental conditions. As well, it is modular, highly reliable, and can be produced at competitive cost using mass production techniques., 2015 1st URSI Atlantic Radio Science Conference (URSI AT-RASC), 2015-5-16 - 24, Gran Canaria, Spain

We describe measurements of both the vibration forces imparted by various types of observatory equipment, and the transmission of these forces through the soil, foundations and telescope pier. These are key uncertainties both in understanding how to mitigate vibration at existing observatories and for developing a vibration budget in the design of future observatories such as the Thirty Meter Telescope. Typical vibration surveys have measured only the resulting motion (acceleration); however, this depends on both the source and the system being excited (for example, isolating equipment results in less force being transmitted, but greater motion of the equipment itself). Instead, here we (a) apply a known force input to the pier from a shaker and measure the response at different locations, and (b) use isolator properties combined with measured acceleration to infer the forces applied by various equipment directly. The soil foundation and pier transmission can then be combined with a finite element model based vibration transmission analysis to estimate the optical consequences. Estimates of plausible source levels supports the development of a vibration budget for TMT that allocates allowable forces to the sources of vibration; this is described in a companion paper., Ground-Based and Airborne Telescopes V, June 22-27, 2014, Series: Proceedings of SPIE; no. 9145

The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 × 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as required to support the TMT science cases. NFIRAOS includes two deformable mirrors, six laser guide star wavefront sensors, and three low-order, infrared, natural guide star wavefront sensors within each client instrument. The first light LGSF system includes six sodium lasers required to generate the NFIRAOS laser guide stars. In this paper, we will provide an update on the progress in designing, modeling and validating the TMT first light AO systems and their components over the last two years. This will include pre-final design and prototyping activities for NFIRAOS, preliminary design and prototyping activities for the LGSF, design and prototyping for the deformable mirrors, fabrication and tests for the visible detectors, benchmarking and comparison of different algorithms and processing architecture for the Real Time Controller (RTC) and development and tests of prototype candidate lasers. Comprehensive and detailed AO modeling is continuing to support the design and development of the first light AO facility. Main modeling topics studied during the last two years include further studies in the area of wavefront error budget, sky coverage, high precision astrometry for the galactic center and other observations, high contrast imaging with NFIRAOS and its first light instruments, Point Spread Function (PSF) reconstruction for LGS MCAO, LGS photon return and sophisticated low order mode temporal filtering., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

This paper describes the current opto-mechanical design of NFIRAOS (Narrow Field InfraRed Adaptive Optics System) for the Thirty Meter Telescope (TMT). The preliminary design update review for NFIRAOS was successfully held in December 2011, and incremental design progress has since occurred on several fronts. The majority of NFIRAOS is housed within an insulated and cooled enclosure, and operates at -30 C to reduce background emissivity. The cold optomechanics are attached to a space-frame structure, kinematically supported by bipods that penetrate the insulated enclosure. The bipods are attached to an exo-structure at ambient temperature, which also supports up to three client science instruments and a science calibration unit., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

Summary form only given. The cost of an antenna element is a key parameter in maximizing the performance per cost ratio of an array. Most current radio telescope array antennas were not designed for high-volume production but generally “only” for performance since typically the production numbers were not large enough to (a) justify the additional design effort and (b) qualify for discount production in terms of amortized tooling costs and quantity purchase. The Allen Telescope Array (ATA) was one of the first radio telescope antenna arrays to be designed for high-volume antenna production.

We provide an update on the development of the first light adaptive optics systems for the Thirty Meter Telescope (TMT) over the past two years. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 x 60 laser guide star (LGS) multi-conjugate AO (MCAO) architecture will provide uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as is required to support TMT science cases. Both NFIRAOS and the LGSF have successfully completed design reviews during the last twelve months. We also report on recent progress in AO component prototyping, control algorithm development, and system performance analysis. © 2012 SPIE., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands, Series: Proceedings of SPIE; no. 8447

NFIRAOS is a diffraction-limited, near-IR, multi-conjugate adaptive optics system. We present an overview of the optical design and design drivers, with particular attention given to the challenges of the laser guide star wavefront sensing optics.