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). NFIRAOS supports three Near Infrared (NIR) client instruments, and provides exceptional image quality across the 2 arcminute field of view. In 2018, NFIRAOS passed the Final Design Review (FDR), but there have been several substantial changes more recently. The optical enclosure (ENCL) refrigeration design was updated for CO2 refrigerant, and an enclosure wall panel was prototyped. The polar-coordinate CCD for the laser guide star (LGS) wavefront sensor camera was replaced with a commercial C-Blue camera from First Light Imaging. More recently, the NFIRAOS Science Calibration Unit (NSCU), which was previously a separate Canadian contribution, was incorporated into the scope of NFIRAOS, and has progressed to the Conceptual Design level. In addition to these changes, the team has been working to bring the last of the low-risk subsystems to final design level in preparation for the beginning of construction.
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.
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 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.
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.
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.
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°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.
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.
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.
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.
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.
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.
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 Herzberg Institute of Astrophysics, Astronomy Technology Research Group's vibration measurement capabilities
include modal test via impulse hammer or electrodynamic exciter, structural response monitoring via piezoelectric
accelerometers, and data acquisition via LabVIEW virtual instruments. This paper will review our existing capabilities,
and give examples of past and future applications relevant to astronomical instrumentation.
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 × 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.
NFIRAOS is the first-light adaptive optics system planned for the Thirty Meter Telescope, and is being designed at the
National Research Council of Canada's Herzberg Institute of Astrophysics. NFIRAOS is a laser guide star multiconjugate
adaptive optics system - a practical approach to providing diffraction limited image quality in the NIR over a
30" field of view, with high sky coverage. This will enable a wide range of TMT science that depends upon the large
corrected field of view and high precision astrometry and photometry. We review recent progress developing the design
and conducting performance estimates for NFIRAOS.
NFIRAOS (Narrow Field InfraRed Adaptive Optics System, pronounced nefarious) is the first light adaptive optics
system for the Thirty Meter Telescope (TMT). It is a near-IR, diffraction limited, multi-conjugate adaptive optics
(MCAO) system that uses two deformable mirrors to correct aberrations due to atmospheric turbulence. The f/15 beam
delivered by the telescope, with a two arc-minute field of view, is relayed to one of three client instrument ports.
Wavefront sensing is accomplished with six high order sodium laser guide star (LGS) wavefront sensors (WFSs) and
three visible natural guide star (NGS) wavefront sensors. Plus, the control system uses two tip/tilt and one focus infrared
WFSs located in the instruments. In this paper, we describe several optical design challenges we have faced. The science
optics have been redesigned to meet evolving specifications, and the LGS WFS design has undergone multiple
iterations. We present an overview of the optical systems and design drivers, including the current state of each design.
NFIRAOS, the TMT Observatory's initial facility AO system is a
multi-conjugate AO system feeding science light from
0.8 to 2.5 microns wavelength to several near-IR client instruments. NFIRAOS has two deformable mirrors optically
conjugated to 0 and 11.2 km, and will correct atmospheric turbulence with 50 per cent sky coverage at the galactic pole.
An important requirement is to have very low background: the plan is to cool the optics; and one DM is on a tip/tilt stage
to reduce surface count. NFIRAOS' real time control uses multiple sodium laser wavefront sensors and up to three IR
natural guide star tip/tilt and/or tip/tilt/focus sensors located within each client instrument. Extremely large telescopes
are sensitive to errors due to the variability of the sodium layer. To reduce this sensitivity, NFIRAOS uses innovative
algorithms coupled with Truth wavefront sensors to monitor a natural star at low bandwidth. It also includes an IR acquisition
camera, and a high speed NGS WFS for operation without lasers. For calibration, NFIRAOS includes simulators
of both natural stars at infinity and laser guide stars at varying range distance. Because astrometry is an important
science programme for NFIRAOS, there is a precision pinhole mask deployable at the input focal plane. This mask is
illuminated by a science wavelength and flat-field calibrator that shines light into NFIRAOS' entrance window. We
report on recent effort especially including trade studies to reduce field distortion in the science path and to reduce cost
and complexity.
Adaptive optics (AO) is essential for many elements of the science case for the Thirty Meter Telescope (TMT). The
initial requirements for the observatory's facility AO system include diffraction-limited performance in the near IR, with
50 per cent sky coverage at the galactic pole. Point spread function uniformity and stability over a 30 arc sec field-ofview
are also required for precision photometry and astrometry. These capabilities will be achieved via an order 60×60
multi-conjugate AO system (NFIRAOS) with two deformable mirrors, six laser guide star wavefront sensors, and three
low-order, IR, natural guide star wavefront sensors within each client instrument. The associated laser guide star facility
(LGSF) will employ 150W of laser power at a wavelength of 589 nm to generate the six laser guide stars.
We provide an update on the progress in designing, modeling, and validating these systems and their components over
the last two years. This includes work on the layouts and detailed designs of NFIRAOS and the LGSF; fabrication and
test of a full-scale prototype tip/tilt stage (TTS); Conceptual Designs Studies for the real time controller (RTC) hardware
and algorithms; fabrication and test of the detectors for the
laser- and natural-guide star wavefront sensors; AO system
modeling and performance optimization; lab tests of wavefront sensing algorithms for use with elongated laser guide
stars; and high resolution LIDAR measurements of the mesospheric sodium layer. Further details may be found in
specific papers on each of these topics.
NFIRAOS (Narrow Field InfraRed Adaptive Optics System, pronounced nefarious) is the first light adaptive optics
system for the Thirty Meter Telescope (TMT). It is a near-IR, diffraction limited, multi-conjugate adaptive optics
(MCAO) system that uses two deformable mirrors to correct aberrations due to atmospheric turbulence. The two arcminute
field of view f/15 beam delivered by the telescope is relayed to one of three client instrument ports. Wavefront
sensing is accomplished with six high order sodium laser guide star (LGS) wavefront sensors (WFSs) and three visible
natural guide star (NGS) wavefront sensors. In this paper, we describe the general layout and design drivers of each
optical system in NFIRAOS. The primary subsystems are the science path optics, the LGS wavefront sensors, the visible
NGS truth WFSs, the IR acquisition camera and the calibration unit. Particular attention is given to the design of the
LGS system, which uses all spherical components and a zoom system to compensate for aberrations and changes in
distance to the sodium layer.
This paper describes the current optical and mechanical designs of NFIRAOS (Narrow Field InfraRed Adaptive Optics
System, pronounced nefarious). The main subsystems are the science path optics, the laser guide star (LGS) wavefront
sensors (WFSs), the visible natural guide star (NGS) truth WFSs, the IR acquisition camera, and a source and calibration
unit. The science optics deliver a diffraction limited f/15 beam with a two arcminute field of view (FOV) to one of three
instruments mounted to NFIRAOS. The LGS system relies on an asterism of five laser guide stars oriented in a 35
arcsecond radius pentagon with a sixth guide star at the center. The LGS optics are comprised of six separate optical
trains that feed individual WFSs. Each optical train includes three zoom mechanisms catering to sodium layer height
variations of 85-235 km. The visible WFS system includes an atmospheric dispersion corrector (ADC); the NGS WFS,
used only for NGS mode; the moderate order radial (MOR) truth WFS, used for fast tracking of radially symmetric
aberrations while in LGS mode; and the high-order low-bandwidth (HOL) truth WFS, used for sensing high-order LGS
WFS offsets. The majority of NFIRAOS is cooled to -30 C to reduce background emissivity. Within the thermal
enclosure are standard optical benches which are semi-kinematically mounted to a sub-structure, which is in turn
connected via bipod flexures to the external NFIFAOS structure. This protects the optics benches from thermal distortion
while maintaining alignment to instruments and TMT.
Atmospheric turbulence compensation via adaptive optics (AO) will be essential for achieving most objectives of the
TMT science case. The performance requirements for the initial implementation of the observatory's facility AO system
include diffraction-limited performance in the near IR with 50 per cent sky coverage at the galactic pole. This capability
will be achieved via an order 60x60 multi-conjugate AO system (NFIRAOS) with two deformable mirrors optically
conjugate to ranges of 0 and 12 km, six high-order wavefront sensors observing laser guide stars in the mesospheric
sodium layer, and up to three low-order, IR, natural guide star wavefront sensors located within each client instrument.
The associated laser guide star facility (LGSF) will consist of 3 50W class, solid state, sum frequency lasers,
conventional beam transport optics, and a launch telescope located behind the TMT secondary mirror.
In this paper, we report on the progress made in designing, modeling, and validating these systems and their components
over the last two years. This includes work on the overall layout and detailed opto-mechanical designs of NFIRAOS and
the LGSF; reliable wavefront sensing methods for use with elongated and time-varying sodium laser guide stars;
developing and validating a robust tip/tilt control architecture and its components; computationally efficient algorithms
for very high order wavefront control; detailed AO system modeling and performance optimization incorporating all of
these effects; and a range of supporting lab/field tests and component prototyping activities at TMT partners. Further
details may be found in the additional papers on each of the above topics.
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