The Dominion Radio Astrophysical Observatory's John A. Galt 26m radio telescope serves multiple roles for the Canadian radio astronomy community. The attributes of this telescope make it ideal for spectropolarimetric studies of the interstellar medium, however instrumental conversion between polarization states of the incoming signal can corrupt the astronomical signal as the telescope undergoes various loading conditions. To characterize these effects, a finite element (FE) model of the telescope was constructed, based on available blueprints and supplemented by manual measurements. To validate this FE model, vibration measurements were conducted over four days in September 2022 by NRC-Herzberg engineers. The telescope was instrumented with accelerometers, and vibrations were excited using the step-release and impulse hammer methods. This paper will briefly review the model development and analytical predictions, will describe the instrumentation plan and experimental approach used, and will summarize key results from these tests, in particular the first several vibration modes of the telescope.

NFIRAOS (Narrow-Field InfraRed Adaptive Optics System) will be the first-light multi-conjugate adaptive optics system for the Thirty Meter Telescope (TMT). The system will be built, tested, and integrated with the first instrument, IRIS (InfraRed Imaging Spectrograph), at Herzberg Astronomy and Astrophysics (HAA) in Victoria BC. NFIRAOS is a complex instrument that will require careful integration planning to meet cost, schedule and performance deliverables. HAA has purpose-built a new facility for the integration of NFIRAOS. We present the key features of this building, and their roles during the assembly, integration, and test phase (AIV). NFIRAOS and IRIS will be fully operational in Victoria, including providing calibration sources, and able to close the adaptive optics (AO) loops with the IRIS On-Instrument Wavefront sensors. NFIRAOS will then be disassembled and shipped to TMT for final construction and commissioning, which requires navigating some logistical challenges.

The NFIRAOS Science Calibration Unit (NSCU) is a large subsystem of NFIRAOS that provides calibration light for the instruments fed by NFIRAOS. It is physically separate from NFIRAOS proper, located outside of the NFIRAOS optics enclosure and ahead of the NFIRAOS entrance window. The NSCU incorporates flat-field illumination sources and the relay optics necessary to inject calibration light into the NFIRAOS optical path, including a fold mirror which is retracted for night-time science observations, allowing telescope light to pass through the NSCU directly into NFIRAOS. The two major requirements of the NFIRAOS science calibration unit (NSCU) are to provide flat-fielding and wavelength-calibration illuminations to NFIRAOS-fed instruments for calibration of scientific data and to provide pupil-simulated telescope beams to NFIRAOS for calibration of the telescope pupil. This paper will summarize the optical and mechanical designs of the NSCU, including light sources and relay optics design, structural trade studies and downselection, and alignment and integration considerations.

The Dominion Radio Astrophysical Observatory’s John A. Galt 26 m radio telescope serves multiple roles for the Canadian radio astronomy community. It is currently earmarked to serve as an interferometric reference for the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Canadian Hydrogen Observatory and Radio Transient Detectors (CHORD), and Deep Dish Development Array 6m (D3A6) experiments. The attributes of this telescope make it ideal for spectropolarimetric studies of the interstellar medium, however instrumental conversion of unpolarized radiation into a polarized signal can corrupt the astronomical signal as the telescope undergoes various loading conditions. To characterize these effects, a finite element (FE) model of the telescope was constructed, based on available blue prints and supplemented by manual measurements. Gravity and wind load cases were analyzed for several elevation angles. The FE model will be validated by measuring the first several vibration modes of the actual telescope using the step-release method. This paper will describe the model development and analytical predictions, as well as the experimental approach used to validate these predictions, and will summarize initial results from these tests (if available).

The Support Structure for the Thirty Meter Telescope (TMT) Infrared Imaging Spectrograph (IRIS) consists of 18 carbonfiber reinforced polymer (CFRP) struts, a CFRP ring and a metal interface frame. This ultra-stiff, lightweight structure suspends the five-ton IRIS Science Cryostat and Rotator below the Narrow Field Infrared Adaptive Optics System (NFIRAOS). Through comprehensive design and analysis driven by requirements for stiffness, optical alignment, adjustability, manufacturability, weight and space, much headway was made to bring this design to fruition. This work presents the current state of design, including material down-selection, adjuster design and strategies for fabrication, alignment and testing. It summarizes methodologies and simulation results examining stiffness, seismic and thermal loads and transmission of vibration between NFIRAOS and IRIS. A prototype strut is being developed and will undergo dynamic mechanical testing to characterize its performance.

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.

Recent changes to the Montreal Protocol have led to the eventual phase-out of hydrofluorocarbon-based refrigerants due to their high global warming potential (GWP). TMT has thus transitioned from R507 (GWP ~ 3900) to CO2 (GWP =1) as the primary observatory supplied refrigerant. Thus, the cooling system for NFIRAOS (TMT’s first light adaptive optics system) was redesigned to work with this high pressure refrigerant. In this paper, we describe the key refrigeration requirements and present the updated design of the NFIRAOS cooling system, including its overall architecture, main components and safety related features. To de-risk aspects of the design and to assess vibration levels of the system (critical for the AO system performance) a prototype CO2 cooling system was built and characterized. Key measurement results are presented.

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.

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 cooled to precisely -30 degrees C in order to improve sensitivity in the near-infrared. It supports up to three client science instruments, including the first-light InfraRed Imaging Spectrograph (IRIS). Powering NFIRAOS is a Real Time Controller that will process the signals from six laser wavefront sensors, one natural guide star pyramid WFS, up to three low-order on-instrument WFS and up to four guide windows on the client instrument's science detector in order to correct for atmospheric turbulence, windshake, optical errors and plate-scale distortion. NFIRAOS is currently preparing for its final design review in late June 2018 at NRC Herzberg in Victoria, British Columbia in partnership with Canadian industry and TMT.

The application of phase diversity is first invested in simulation to characterize ideal parameters to GPI with faithfully simulated calibration source data. The best working simulation parameters are applied to real GPI data and shown to recover an injected astigmatism. The estimated GPI NCPA are then corrected and the Strehl ratio is improve by ⇠ 5%, although the application is rudimentary and a more thorough correction will be applied in the near future.

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 NFIRAOS Beamsplitters (NBS), and the NFIRAOS Source Simulator system (NSS) comprising the Focal Plane Mask (FPM), the Laser Guide Star (LGS) sources, and the 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.

The Narrow Field InfraRed Adaptive Optics System (NFIRAOS) will be the first-light facility adaptive optics system for the Thirty Meter Telescope (TMT). In order to meet the optical performance and stability specifications essential to leveraging the extraordinary capabilities of the TMT, all of the optical components within NFIRAOS will be protected within a large thermally-controlled optics enclosure (ENCL). Among the many functions performed by the ENCL, the most critical functions include providing a highly stable, light-tight, cold, dry environment maintained at 243±0.5 K for the NFIRAOS opto-mechanical sub-systems and supporting TABL structure. Although the performance of the ENCL during the science operation of NFIRAOS is critical, the maximum thermal loading will be defined by the cooldown/ warm-up cycle which must be accomplished within a time-frame that will minimize the on-sky operational impact due to daytime maintenance work. This study describes the thermal/mechanical design development and supporting analyses (analytical and finite element analyses (FEA)) completed during the preliminary design phase and through the current progression of the ENCL final design phase. The walls of the ENCL consist of interlocking, multilayered, thermally insulated panels, which are supported by an externally located structural framework which attaches to the NFIRAOS Instrument Support Structure. The regulation of the interior ENCL wall surface temperature to within ±0.5 K requires that the heat flux into the interior of NFIRAOS be eliminated by cooling a thermal conduction plate embedded between multiple layers of insulation. The thermal design of the enclosure was evaluated for both steady-state (SS) performance and transient performance (cool-down and warm-up cycles). The transient analysis utilizes a hybrid of a one-dimensional thermal network approach combined with three-dimensional conjugate heat transfer analyses of explicit opto-mechanical components within the ENCL. Many design-parameter combinations were evaluated to determine the performance impact of cooling power and transient temperature profiles. The results derived from the analyses of these design iterations indicate the multi-layer enclosure wall design will meet all thermal requirements. During SS operation, the interior temperature variation is within ±0.5 K of the target operational temperature, while the heat influx from the exterior TMT environment is 1528 W (extracted by the embedded cold plate). The transient cool-down cycle will take approximately 15 hours to complete and requires the in-situ air handling units to deliver 14KW of cooling power (derated for the TMT site conditions) throughout the interior space of the NFIRAOS ENCL.

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.

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 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.

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 high-contrast imaging.

The Square Kilometre Array (SKA) requires roughly 2000+ 15m reflector antennas to implement a radio telescope with a collecting area equivalent to 1 million square metres. The cost and performance of these antennas impact the telescope significantly. In this paper we report the results of developing the SKA Dish Verification Antenna-1 - a novel 15m dual offset Gregorian design using single-piece rim supported primary and secondary reflectors made of carbon reinforced plastic which yield cost and performance advantages.