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Focal plane wavefront sensing and control has been identified as a crucial technology to enable high contrast imaging down to terrestrial mass, habitable zone exoplanets with future observatories. However, open questions remain as to how such algorithms should be integrated into existing systems to enable reaching their optimal performance, particularly for ground-based adaptive optics (AO). In this paper we use numerical simulations to show that a focal plane wavefront sensing and control technique running on millisecond timescales, called the Fast Atmospheric Self-coherent camera Technique (FAST), can be designed to operate as a “second stage” AO wavefront sensor (WFS), both for low and high order active wavefront control. Accordingly, we propose a closed-loop real-time controller architecture to use both an AO and FAST WFS to control a common DM.

The SAM616 is a prototype deformable mirror built by CILAS for the Thirty Meter Telescope’s Narrow Field Infrared Adaptive Optics System (NFIRAOS). It was delivered to NRC-HAA in August 2018 for performance testing at room temperature and at the operating temperature of NFIRAOS, -30oC. Properties that were measured include the total stroke, hysteresis, creep and coupling of the actuators, as well as the flattening ability at various temperatures. The mirror has been found to meet (and in some case exceed) all its performance requirements including its flattening requirements.

High-contrast imaging instruments have advanced techniques to improve contrast, but they remain limited by uncorrected stellar speckles, often lacking a “second stage” correction to complement the Adaptive Optics (AO) correction. We are implementing a new second stage speckle-correction solution for the Gemini Planet Imager (GPI), replacing the instrument calibration unit (CAL) with the Fast Atmospheric Self coherent camera Technique (FAST), a new version of the self-coherent camera (SCC) concept. Our proposed upgrade (CAL2.0) will use a common-path interferometer design to enable speckle correction, through post-processing and/or by a feedback loop to the AO deformable mirror. FAST utilizes a new type of coronagraphic mask that will enable, for the first time, speckle correction down to millisecond timescales. The system's main goal is to improve the contrast by up to 100x in a halfdark hole to enable a new regime of science discoveries. Our team has been developing this new technology at the NRC's Extreme Wavefront control for Exoplanet and Adaptive optics Research Topics (NEW EARTH) laboratory over the past several years. The GPI CAL2.0 update is funded (November 2020), and the system’s first light is expected late 2023., Adaptive Optics Systems VII, December 14-18, 2020, Online Only, United States

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 InfraRed Imaging Spectrograph (IRIS) is the first-light client instrument for the Narrow Field Infrared Adaptive Optics System (NFIRAOS) on the Thirty Meter Telescope (TMT). Now approaching the end of its final design phase, we provide an overview of the instrument control software. The design is challenging since IRIS has interfaces with many systems at different stages of development (e.g., NFIRAOS, telescope control system, observatory sequencers), and will be built using the newly-developed TMT Common Software (CSW), which provides framework code (Java/Scala), and services (e.g., commands, telemetry). Lower-level software will be written in a combination of Java and C/C++ to communicate with hardware, such as motion controllers and infrared detectors. The overall architecture and philosophy of the IRIS software is presented, as well as a summary of the individual software components and their interactions with other systems., Comment: 20 pages, 9 figures, SPIE (2020) 11452-28

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, equipped with back-illuminated pinhole mask, can be utilized to measure instrumental optical distortions. AO systems on the largest ground-based telescopes, such as the W. M. Keck Observatory and the Thirty Meter Telescope require pinhole positions known to 20 nm to achieve an astrometric precision of 0.001 of a resolution element. We characterize a photo-lithographic pinhole mask and explore the systematic errors that result from different experimental setups. We characterized the nonlinear geometric distortion of a simple imaging system using the mask; and we measured 857 nm RMS of optical distortion with a final residual of 39 nm (equivalent to 20 ��as for TMT). We use a sixth order bivariate Legendre polynomial to model the optical distortion and allow the reference positions of the individual pinholes to vary. The nonlinear deviations in the pinhole pattern with respect to the manufacturing design of a square pattern are 47.2 nm +/- 4.5 nm (random) +/- 10.8 nm (systematic) over an area of 1788 mm$^2$. These deviations reflect the additional error induced when assuming the pinhole mask is manufactured perfectly square. We also find that ordered mask distortions are significantly more difficult to characterize than random mask distortions as the ordered distortions can alias into optical camera distortion. Future design simulations for astrometric calibration units should include ordered mask distortions. We conclude that photo-lithographic pinhole masks are >10 times better than the pinhole masks deployed in first generation AO systems and are sufficient to meet the distortion calibration requirements for the upcoming thirty meter class telescopes., 20 pages, 13 figures

The paper deals with with the on-sky performance of the pyramid wavefront sensor-based Adaptive Optics (AO) systems. These wavefront sensors are of great importance, being used in all first light AO systems of the ELTs (E-ELT, GMT, and TMT), currently in design phase. In particular, non-common path aberrations (NCPAs) are a critical issue encountered when using an AO system to produce corrected images in an associated astronomical instrument. The AO wavefront sensor (WFS) and the supported scientific instrument typically use a series of different optical elements, thus experiencing different aberrations. The usual way to correct for such NCPAs is to introduce a static offset in the WFS signals. In this way, when the AO loop is closed the sensor offsets are zeroed and the deformable mirror converges to the shape required to null the NCPA. The method assumes that the WFS operation is linear and completely described by some pre-calibrated interaction matrix. This is not the case for some frequently used wavefront sensors like the Pyramid sensor or a quad-cell Shack-Hartmann sensor. Here we present a method to work in closed-loop with a pyramid wavefront sensor, or more generally a non-linear WFS, introducing a wavefront offset that remains stable when AO correction quality changes due to variations in external conditions like star brightness, seeing, and wind speed. The paper details the methods with analytical and numerical considerations. Then we present results of tests executed at the LBT telescope, in daytime and on sky, using the FLAO system and LUCI2 facility instrument. The on-sky results clearly show the successful operation of the method that completely nulls NCPA, recovering diffraction-limited images with about 70% Strehl ratio in H band in variable seeing conditions. The proposed method is suitable for application to the above-mentioned ELT AO systems.

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., Adaptive Optics Systems VI, June 10-15, 2018, Austin, United States, Series: Proceedings of SPIE; no. 10703

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 Real-Time Controller (RTC) for the Thirty Meter Telescope (TMT) Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the software and server hardware that converts wavefront error measurements into wavefront corrector demands, at the heart of the laser guide star multi-conjugate adaptive optics (MCAO) or natural guide star adaptive optics (NGS AO). The RTC takes input from up to six Shack-Hartmann Laser Guide Star wavefront sensors (LGS WFS), one high-order Natural Guide Star Pyramid Wavefront Sensor (PWFS), up to three Shack-Hartmann On-Instrument wavefront sensors (OIWFS) that are located in the client science instruments, and up to 4 on-detector guide windows (ODGW) also in the client instruments. The RTC controls two deformable mirrors conjugated to 0km (DM0) and 11.8km (DM11). DM0 is mounted on a tip/tilt stage (TTS). During the final design phase we performed prototyping to verify that off-the-shelf servers using general purpose CPUs are able to support the maximum 800 Hz frequency at which the RTC is required to operate. We also considered methods to provide live data streams to a graphical user interface without impacting the AO system performance. This paper will discusses the outcome of the impact of jitter and latency on loop speed in our prototype and an overview of the RTC pipeline, including the many “knobs” that can be turned to fine-tune the behavior of NFIRAOS in different observing modes, and under different observing conditions.

The InfraRed Imaging Spectrograph (IRIS) is the first-light client instrument for the Narrow Field Infrared Adaptive Optics System (NFIRAOS) on the Thirty Meter Telescope (TMT). IRIS includes three natural guide star (NGS) On-Instrument Wavefront Sensors (OIWFS) to measure tip/tilt and focus errors in the instrument focal plane. NFIRAOS also has an internal natural guide star wavefront sensor, and IRIS and NFIRAOS must precisely coordinate the motions of their wavefront sensor positioners to track the locations of NGSs while the telescope is dithering (offsetting the telescope to cover more area), to avoid a costly re-acquisition time penalty. First, we present an overview of the sequencing strategy for all of the involved subsystems. We then predict the motion of the telescope during dithers based on finite-element models provided by TMT, and finally analyze latency and jitter issues affecting the propagation of position demands from the telescope control system to individual motor controllers., 21 pages, 19 figures, SPIE (2018) 10707-49

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 Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the first light Adaptive Optics (AO) system for the Thirty Meter Telescope (TMT). A critical component of NFIRAOS is the Real-Time Controller (RTC) subsystem which provides real-time wavefront correction by processing wavefront information to compute Deformable Mirror (DM) and Tip/Tilt Stage (TTS) commands. The National Research Council of Canada - Herzberg (NRC-H), in conjunction with TMT, has developed a preliminary design for the NFIRAOS RTC. The preliminary architecture for the RTC is comprised of several Linux-based servers. These servers are assigned various roles including: the High-Order Processing (HOP) servers, the Wavefront Corrector Controller (WCC) server, the Telemetry Engineering Display (TED) server, the Persistent Telemetry Storage (PTS) server, and additional testing and spare servers. There are up to six HOP servers that accept high-order wavefront pixels, and perform parallelized pixel processing and wavefront reconstruction to produce wavefront corrector error vectors. The WCC server performs low-order mode processing, and synchronizes and aggregates the high-order wavefront corrector error vectors from the HOP servers to generate wavefront corrector commands. The Telemetry Engineering Display (TED) server is the RTC interface to TMT and other subsystems. The TED server receives all external commands and dispatches them to the rest of the RTC servers and is responsible for aggregating several offloading and telemetry values that are reported to other subsystems within NFIRAOS and TMT. The TED server also provides the engineering GUIs and real-time displays. The Persistent Telemetry Storage (PTS) server contains fault tolerant data storage that receives and stores telemetry data, including data for Point-Spread Function Reconstruction (PSFR).

A pyramid wavefront sensor (PWFS) bench has been setup at NRC-Herzberg (Victoria, Canada) to investigate, first, the feasibility of a double roof prism PWFS, and second, test the proposed pyramid wavefront sensing methodology to be used in NFIRAOS for the Thirty Meter Telescope. Traditional PWFS require shallow angles and strict apex tolerances, making them difficult to manufacture. Roof prisms, on the other hand, are common optical components and can easily be made to the desired specifications. Understanding the differences between a double roof prism PWFS and traditional PWFS will allow for the double roof prism PWFS to become more widely used as an alternative to the standard pyramid, especially in a laboratory setting. In this work, the response of the double roof prism PWFS as the amount of modulation is changed, is compared to an ideal PWFS modelled using the adaptive optics toolbox, OOMAO in MATLAB. The object oriented toolbox uses physical optics to model complete AO systems. Fast modulation and dithering using a PI mirror has been implemented using a micro-controller to drive the mirror and trigger the camera. The various trade offs of this scheme, in a controlled laboratory environment, are studied and reported.

Prototyping and benchmarking was performed for the Real-Time Controller (RTC) of the Narrow Field InfraRed Adaptive Optics System (NFIRAOS). To perform wavefront correction, NFIRAOS utilizes two deformable mirrors (DM) and one tip/tilt stage (TTS). The RTC receives wavefront information from six Laser Guide Star (LGS) Shack- Hartmann WaveFront Sensors (WFS), one high-order Natural Guide Star Pyramid WaveFront Sensor (PWFS) and multiple low-order instrument detectors. The RTC uses this information to determine the commands to send to the wavefront correctors. NFIRAOS is the first light AO system for the Thirty Meter Telescope (TMT). The prototyping was performed using dual-socket high performance Linux servers with the real-time (PREEMPT_RT) patch and demonstrated the viability of a commercial off-the-shelf (COTS) hardware approach to large scale AO reconstruction. In particular, a large custom matrix vector multiplication (MVM) was benchmarked which met the required latency requirements. In addition all major inter-machine communication was verified to be adequate using 10Gb and 40Gb Ethernet. The results of this prototyping has enabled a CPU-based NFIRAOS RTC design to proceed with confidence and that COTS hardware can be used to meet the demanding performance requirements.

For today and future adaptive optics observations, sodium laser guide stars (LGSs) are crucial; however, the LGS elongation problem due to the sodium layer has to be compensated, in particular for extremely large telescopes. In this paper, we describe the concept of truth wavefront sensing as a solution and present its design using a pyramid wavefront sensor (PWFS) to improve NFIRAOS (Narrow Field InfraRed Adaptive Optics System), the first light adaptive optics system for Thirty Meter Telescope. We simulate and test the truth wavefront sensor function under a controlled environment using the HeNOS (Herzberg NFIRAOS Optical Simulator) bench, a scaled-down NFIRAOS bench at NRC-Herzberg. We also touch on alternative pyramid component options because despite recent high demands for PWFSs, we suffer from the lack of pyramid supplies due to engineering difficulties.

Measurement errors due to aliasing in a Shack-Hartmann WFS are typically 40% larger in variance than the fitting error of an AO system. On bright stars, aliasing is the dominant error within the control radius of the deformable mirror. Wavefront spatial frequencies beyond the WFS’ Nyquist frequency corrupt measurements below this frequency. A common misconception is to think that aliasing primarily affects the higher spatial frequency measurements. But in fact aliasing propagates to the lowest order modes, and corrupts even tip/tilt. There are many examples including the observation that the temporal power spectrum of measured tip/tilt from a WFS does not correspond to Kolmogorov theory. We propose a simple optical modification to a SH WFS (borrowed from the digital video camera industry), and present simulation results showing that the aliasing errors are reduced.

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.

The InfraRed Imaging Spectrograph (IRIS) will be the first light adaptive optics instrument on the Thirty Meter Telescope (TMT). IRIS is being built by a collaboration between Caltech, the University of California, NAOJ and NRC Herzberg. We present novel aspects of the Support Structure, Rotator and On-Instrument Wavefront Sensor systems being developed at NRC Herzberg. IRIS is suspended from the bottom port of the Narrow Field Infrared Adaptive Optics System (NFIRAOS), and provides its own image de-rotation to compensate for sidereal rotation of the focal plane. This arrangement is a challenge because NFIRAOS is designed to host two other science instruments, which imposes strict mass requirements on IRIS. We have been tasked with keeping the instrument mass under seven tonnes which has resulted in a mass reduction of 30 percent for the support structure and rotator compared to the most recent IRIS designs. To accomplish this goal, while still being able to withstand earthquakes, we developed a new design with composite materials. As IRIS is a client instrument of NFIRAOS, it benefits from NFIRAOS's superior AO correction. IRIS assists this correction by sensing low-order aberrations with an On-Instrument Wavefront Sensor (OIWFS). The OIWFS consists of three independently positioned natural guide star wavefront sensors that patrol a 2-arcminute field of view. We expect tip-tilt measurements from faint stars within the IRIS imager focal plane will further stabilize the delivered image quality. We describe how the use of On-Detector Guide Windows (ODGWs) in the IRIS imager can be incorporated into the AO correction. Finally, we present our strategies for acquiring and tracking sources with this complex AO system, and for mitigating and measuring the various potential sources of image blur and misalignment due to properties of the mechanical structure and interfaces. (Abridged), Comment: 11 pages, 8 figures, SPIE (2016) 9908-381

High order AO subsystems of the ELT require technological advancements in the Deformable Mirror (DM) construction and corresponding improvements in the drive electronics. Advanced prototyping is currently under way at NSI-Herzberg to reduce risks of deploying untried technology in the TMT AO subsystem NFIRAOS. We have developed a 96-channel output module and constructed a sub-scale DM Electronics prototype NDME384 with 384 output channels based on 4 such modules. French DM vendor Cilas has fabricated the NFIRAOS DM Breadoboard with 360 piezoelectric actuators in a 60×6 matrix, to demonstrate the DM technology to be deployed in NFIRAOS wavefront correctors. We present the results of testing our NDME384 prototype while driving the NFIRAOS DM Breadoboard., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron) integral field spectrograph and imaging camera for the Thirty Meter Telescope (TMT). With extremely low wavefront error (, Ground-Based and Airborne Instrumentation for Astronomy V, June 22-26, 2014, Series: Proceedings of SPIE; no. 9147

We explore two methods of quantifying and correcting non-common path aberrations (NCPA) both in simulation and on an experimental bench. The first method, called Focal Plane Sharpening (FPS), utilizes an optimization algorithm to maximize the peak intensity of the PSF by varying actuator patterns on a deformable mirror (DM). The second method employs the technique of Phase Diversity (PD) to estimate NCPA by use of PSF images in and out of the focal plane. The experimental tests use a 52 actuator ALPAO DM and 1000 actuator MEMS DM to provide an offset for NCPA correction. Each method shows to be successful in simulation, however FPS is the only method used successfully on an experimental bench; although work is on-going to successfully demonstrate PD. Our aim is to use one or both methods to determine the best approach to NCPA calibration on the MOAO system RAVEN, and extend this calibration method to future systems such as TMT's NFIRAOS.

With two large deformable mirrors with a total of more than 7000 actuators that need to be driven from the measurements of six 60x60 LGS WFSs (total 1.23Mpixels) at 800Hz with a latency of less than one frame, NFIRAOS presents an interesting real-time computing challenge. This paper reports on a recent trade study to evaluate which current technology could meet this challenge, with the plan to select a baseline architecture by the beginning of NFIRAOS construction in 2014. We have evaluated a number of architectures, ranging from very specialized layouts with custom boards to more generic architectures made from commercial off-the-shelf units (CPUs with or without accelerator boards). For each architecture, we have found the most suitable algorithm, mapped it onto the hardware and evaluated the performance through benchmarking whenever possible. We have evaluated a large number of criteria, including cost, power consumption, reliability and flexibility, and proceeded with scoring each architecture based on these criteria. We have found that, with today's technology, the NFIRAOS requirements are well within reach of off-the-shelf commercial hardware running a parallel implementation of the straightforward matrix-vector multiply (MVM) algorithm for wave-front reconstruction. Even accelerators such as GPUs and Xeon Phis are no longer necessary. Indeed, we have found that the entire NFIRAOS RTC can be handled by seven 2U high-end PC-servers using 10GbE connectivity. Accelerators are only required for the off-line process of updating the matrix control matrix every ∼10s, as observing conditions change., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

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

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., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

One of the first ELT AO systems to be deployed will be NFIRAOS of the Thirty Meter Telescope (TMT). NFIRAOS is currently being designed at the National Research Council of Canada's Herzberg Institute of Astrophysics (HIA). NFIRAOS incorporates deformable mirrors with much larger number of actuators than in current AO systems. To aid the procurement of electronics for NFIRAOS DMs, a reference design is under way at the HIA. We have designed the overall architecture, defined a command communication interface and developed a compact and cost-efficient high voltage amplifier suitable for duplicating in 7673 copies for driving the two NFIRAOS DMs., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands

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.

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

Adaptive Optics Real-Time Control systems for next generation ground-based telescopes demand significantly higher processing power, memory bandwidth and I/O capacity on the hardware platform than those for existing control systems. We present a FPGA based high-performance computing platform that is developed at Dominion Radio Astrophysical Observatory and is very suitable for the applications of Adaptive Optics Real-Time Control systems. With maximum of 16 computing blades, 110 TeraMAC/s processing power, 1.8Terabyte/s memory bandwidth and 19.5 Terabit/s I/O capacity, this ATCA architecture platform has enough capacity to perform pixel processing, tomographic wave-front reconstruction and deformable mirror fitting for first and second generation AO systems on 30+-meter class telescopes. As an example, we demonstrate that with only one computing blade, the platform can handle the real time tomography needs of NFIRAOS, the Thirty-Meter Telescope first light facility Multi-Conjugate Adaptive Optics system. The High-Performance FPGA platform is integrated with Board Software Development Kit to provide a complete and fully tested set of interfaces to access the hardware resources. Therefore the firmware development can be focused on unique, user-specific applications. © 2012 SPIE., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, the Netherlands, Series: Proceedings of SPIE; no. 8447

Advanced wide-field AO systems, such as Multi-Conjugate AO (MCAO) systems often require many static optical elements (mirror and lenses) in addition to the active ones (deformable mirrors). These static elements induce additional wave-front errors due to random fabrication errors such as polishing errors. For ELT-size AO systems, these optical elements can be very large, and thus their cost and availability critically depends on how of much fabrication error can be tolerated. Therefore, a rigorous tolerance analysis is absolutely critical. Requirements can, in principle be relaxed, on account that fabrication errors with spatial scales larger than the inter-actuator spacing of the deformable mirrors (DMs) can be corrected. However, this process is significantly complicated by the fact that these optical elements are often conjugated far away from the DMs, and therefore DM correction cannot be achieved over a wide field of view (FOV). In this paper, we present our tolerance analysis in the context of NFIRAOS, the first-light MCAO system for the Thirty Meter Telescope. We start from two top-level error budgets: the "on-axis error budget, which specifies the acceptable residual wave-front error in the narrow 17''x17'' science FOV; and the "off-axis" error budget, which specifies the acceptable residual wave-front error at the edge of the 2' diameter technical FOV. The former directly relates to science image quality, whereas the latter directly relates to sky coverage. For different assumptions on the spatial power spectrum of the polishing errors, we derive the requirements on each optical element in NFIRAOS using a Monte-Carlo analysis of the predicted off-axis performance of the system with on axis AO correction. © 2012 SPIE., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, the Netherlands, Series: Proceedings of SPIE; no. 8447

This paper presents an overview of the PDR level mechanical and opto-mechanical design of the cryogenic spectrograph unit of the nIR spectropolarimeter (SPIROU) proposed as a new-generation instrument for CFHT. The design is driven by the need for high thermo-mechanical stability in terms of the radial velocity (RV) of 1 m/s during one night, with the requirement for thermal stability set at 1 mK/24 hours. This paper describes stress-free design of the cryogenic optical mounts, mechanical design of the custom-build cryostat, mechanical design of the optical bench, and thermal design for 1 mK thermal stability. The thermal budget was calculated using lumped-mass model thermal analysis, implemented in Modelica multi-domain modeling language. Discussion of thermal control options to achieve 1 mK thermal stability is included. © 2012 SPIE., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, The Netherlands, Series: Proceedings of SPIE; no. 8446

Laser-guide-star-based multi-conjugate adaptive optics (MCAO) systems require natural guide-stars to measure tilt and tilt-anisoplanatism modes. This paper focuses on the parameter optimisation of sub-optimal integrator-based controllers using a single and a double integrator (baseline option) to drive the low-order loop of NFIRAOS, the 1st light MCAO system for the Thirty-Meter Telescope. The minimum-variance (MV) controller is outlined, against which integrators are compared. Simulations using ∼500 asterisms considered in sky-coverage simulations for the TMT show that the double integrator gives competitive results thoughout the range of asterisms and magnitudes considered. It is shown that using an optimal modal gain integrator can further improve the performance with respect to using an averaged gain for all of part of the modes. However, it is outperformed by the MV controller, in particular for asterisms with relatively dim stars (lower bound is magnitude 22 in H-band) requiring low temporal frame-rates (as low as 16Hz) to integrate more flux. Over all the cases tested, an average of ∼100 nm rms (23 nm rms median) improvement can be achieved with the MV. The MV further increases by 15% the probability of working below the 50th-percentile residual of the double integrator. © 2012 SPIE., Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, the Netherlands, Series: Proceedings of SPIE; no. 8447

We present the results of the design studies of the science calibration system for the adaptive optics and infrared instruments of the Thirty Meter Telescope. The two major requirements of the science calibration system are to provide pupil-simulated telescope beams to the adaptive optics system for calibration of the telescope pupil and to provide flatfielding and wavelength-calibration illuminations to client instruments of the adaptive optics system. Our current system is composed an integrating sphere with calibration light sources, a retractable pupil-mask system, a lens assembly consisting of a pair of achromatic triplets, and fold mirrors. This system appears to be capable of producing highlyuniform of f/15 beams at the telescope focal plane and pupil simulation at a pupil location within the adaptive optics system. We describe the present design and development of the calibration system along with relevant analyses.

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 60x60 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 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.

LGS wavefront sensing on ELTs is challenging. The tip-tilt indetermination, the cone effect, the star elongation, the sodium profiles fluctuations are the main problems plaguing LGS wavefront sensors. The AO Laboratory at the University of Victoria has build a LGS wavefront sensing test bed scaled for the TMT, reproducing the sodium variations and the whole NFIRAOS wavefront sensing scheme. The details of the bench design are given and the implementation of the wavefront sensing algorithm is presented. This one includes a matched filter, zoom optics control, DM command and truth wavefront sensors management., 1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, June 22-26, 2009, Paris, France

We present the scientific gain enjoyed by client instruments when NFIRAOS is cooled. If NFIRAOS is cooled to -24◦ C, the background contribution of NFIRAOS will not exceed 15% of the background from sky plus TMT (for a telescope build to current requirements on Mauna Kea). If cooled further to -30◦ C, the K-band inter-OH background-limited exposure times could decrease by more than 7%. We evaluate these gains achieved by cooling NFIRAOS in light of increased technical risks and costs., 1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, June 22-26, 2009, Paris, France

Sodium Laser Guide Stars (LGS) induce optical aberrations in adaptive optics (AO) systems.The artificial star is elongated due to the sodium layer thickness, and the variations of thesodium layer altitude and atom density profile induce errors on centroid measurements ofelongated spots. In AO systems, these errors generate spurious optical aberrations, termed LGSaberrations, especially with ELTs for which the spot elongation is greater. According toanalytical models and experimental results obtained with the University of Victoria LGS benchdemonstrator, we characterized the main LGS aberrations and studied two options to mitigatethem: the Radial Thresholding and the temporal filtering., 1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, June 22-26, 2009, Paris, France

We outline a concept design for an FPGA based real-time adaptive optics controller that meets the requirements of the Thirty Meter Telescope (TMT) first light Narrow Field Infrared Adaptive Optics system (NFIRAOS). The data and processing rates for NFIRAOS are very demanding. It has pixel input rates of about 5 GB/s and processing requirements of order several hundred GMACs. The hardware proposed is programmable and flexible, and can be used in other AO systems. It is based on a custom FPGA compute blade housed with COTS interface and computer boards in an ATCA chassis. The system accepts data from eight wave front sensors at 10 Gbps each via thirty-two serial front panel data ports (sFPDPs). Nine FPGA blades provide about 2.7 TMAC/s of processing power and are used to perform pixel processing, tomography and deformable mirror fitting. Two general-purpose computer boards are used to perform background processing and control, each with three Intel L7400 dual core processors. The system is also capable of storing 90 TB of telemetry data at rate of 3.5 GB/s., 1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, June 22-26, 2009, Paris, France

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 presents a type II control architecture that will be use in NFIRAOS on TMT to control tip-tilt and the plate scale modes measured by the on-instrument wave-front sensors.

Sodium laser guide stars (LGSs) allow, in theory, full sky coverage, but have their own limitations. Variations of sodium layer altitude, thickness and atom density profile induce changing errors on wavefront measurements (LGS aberrations), especially with ELTs for which the LGS spot elongation is larger. In the framework of the Thirty-Meter-Telescope project (TMT), the AO-Lab of the University of Victoria (UVic) built a LGS-simulator test bed in order to assess the performance of new centroiding algorithms for LGS Shack-Hartmann wavefront sensors (SH-WFS). The principle of the LGS-bench is briefly reviewed. The closed-loop performances of the matched filter (MF) algorithm on laboratory 29x29 elongated spot images are presented and compared with the centre of gravity (CoG). The ability of the MF to track the LGS aberrations is successfully demonstrated. The UVic LGS-bench is not limited to SH-WFS and can serve as a LGS-simulator test bed to any other LGS-AO projects for which sodium layer fluctuations are an issue.

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.