The New Robotic Telescope (NRT) is an autonomous telescope that can operate multiple instruments at the Cassegrain focal station and the straight-through port. The optical beam is directed to the ports by a fold mirror subsystem in the focal station assembly. The fold mirror is elliptical in shape, manufactured by Instituto Nazionale di Astrofisica (INAF), and polished down to RMS surface deformation of λ/20. An optomechanical analysis is performed to simulate the effect of gravity over the mirror surface deformation and the results have been compared to the interferometry plots to optimize the Ion Beam Figuring (IBF) process to polish the mirror aperture. The mirror assembly is supported by a bipod flexure design to reduce surface deformation under gravity and thermal loads. There are three sets of bipod elements and a central support in the quasi-kinematic support structure. Using wire EDM, the bipods were manufactured precisely as one piece. Following careful preparation and the development of multiple glue jigs to ensure an even glue thickness, the bipods, and central pads are glued to the mirror, and multiple experimental tests have been performed to ensure the glue layer's strength and durability. Other components of the mirror assembly, such as the mirror cell, mirror stand, and moving platform, are being machined out of INVAR, assembled, and mounted on the linear stage and a rotary stage before being installed over the mechanism platform in the A&G box. The design and manufacturing of the mirror assembly, including the gluing process, will be summarised as part of this article.
A-DOT (Active Deployable Optical Telescope) is a payload prototype of a 6U deployable telescope operating in the visible from 400 to 800 nm with an aperture diameter of 300 mm. It aims to deliver diffraction-limited performance using on-board wavefront sensing (WFS) and active control (WFC). A-DOT is currently in the design phase. This paper presents the development of a deployable, single-segment, mechanical prototype. The deployable mirror segment is kinematically mounted to a monolithic flexure using three spherical contacts in a cup-grooveflat arrangement. Tip, tilt and piston (PTT) are controlled using linear, piezoelectric actuators at each contact and the mirror position measured using capacitive sensors. The prototype is packaged within the allowable CubeSat volume and uses space-compatible hardware in a non-magnetic design.
A-DOT (Active Deployable Optical Telescope) is a payload prototype project of a 6U segmented deployable telescope with an aperture diameter of 300 mm currently in the design phase. This paper investigates two different strategies for phasing a deployable segmented telescope. The first method employs a classical optimisation approach, where the image sharpness is used as the primary metric for aligning the mirror segments. This technique involves iteratively adjusting the individual segments' positions and orientations to maximise the resulting image's sharpness. The second method takes a more innovative approach by leveraging the power of deep learning techniques. Deep learning algorithms, trained on a large dataset of simulated images, can learn to recognise and correct phasing errors automatically. This approach can potentially streamline the phasing process and enhance the telescope's overall performance. Preliminary results from the study demonstrate the efficacy of both methods in achieving excellent phasing control. Remarkably, these techniques have successfully identified and corrected significant phasing errors, with path length differences of several microns, ultimately reducing the residual errors to the desired performance level using a point source, typically below 15 nm in the visible spectrum.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 470 nm to 2450 nm with resolving powers from 3300 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. To model the optical performance we include manufacturing and alignment tolerances alongside other static and dynamic effects. Diffraction of both image and pupil become significant when the spectrograph slit width matches the diffraction limited point spread function. A set of Zemax OpticStudio macros and Python scripts are used to bring together the subsystem models that make up HARMONI and combine them to include all these effects. We present an overview of our approach to modelling this complex instrument and key results predicting the optical performance of HARMONI.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. HARMONI is a work-horse instrument that provides efficient, spatially resolved spectroscopy of extended objects or crowded fields of view. The gigantic leap in sensitivity and spatial resolution that HARMONI at the ELT will enable promises to transform the landscape in observational astrophysics in the coming decade. The project has undergone some key changes to the leadership and management structure over the last two years. We present the salient elements of the project restructuring, and modifications to the technical specifications. The instrument design is very mature in the lead up to the final design review. In this paper, we provide an overview of the instrument's capabilities, details of recent technical changes during the red flag period, and an update of sensitivities.
The New Robotic Telescope will be a fully autonomous, rapid reaction, primarily spectroscopic facility for the classification of astronomical transients. The 4.18m diameter primary mirror is to be composed of 18 hexagonal mirror segments, arranged with a secondary mirror that feeds the Cassegrain focal stations with an F/10.635 beam. The final telescope design does not follow an established prescription, although both primary and secondary remain hyperbolic. However, the tube length is retained from an earlier F/7.5 RC design and secondary mirror size reduced to minimise obscuration of the primary. The optimisation process involved considering the M2 / fold size trade-off while solving the surfaces for image quality, contrast and wavefront error after speeding up the primary mirror. The final effective focal ratio is then slower to allow for workable tolerances through manufacture, installation and operations. In this presentation the optimisation process, trade-offs, tolerances and final design will be summarised.
The Galway Liverpool imaging polarimeter (GLIP) has been designed to perform simultaneous linear and circular polarimetric measurements at sub-second cadence. The science goal of the instrument is to perform observations of fast evolving astronomical transients with leading robotic telescope facilities. GLIP builds on the legacy of polarimeter instruments developed by the Liverpool Telescope team of the Astrophysical Research Institute, Liverpool, with the RINGO & MOPTOP series, and the National University of Ireland Galway (NUIG) with the GASP polarimeter. The instrument works as a four-beam imaging polarimeter of a 2.3 arc-minute field-of-view onto one detector, allowing the determination of the full Stokes vector [I Q U V] across the image field once the characteristic matrix of the instrument is known. Optical design, characterisation of polarimetry and tolerance of the instrument optical components using computational, lab testing result & mathematical methods will be discussed.
The New Robotic Telescope will be 4-meter class telescope with a fast response time (less than 30 seconds) as its primary design target. To achieve this, enough structural stiffness and a quick settling time are key factors. Over the last year, important updates to the structure have been carried out. The biggest update consists of changing the tube from a Serrurier Truss to a Multibay Truss, a tube that is more common in bigger telescopes, which provides more stiffness at a lower weight, enabling better drive performance and low settling times. A new design of the M1 Cell has also been designed, as well as updating some key parts of the structure in response to the optical specification update, that has changed from f/7.5 to f/10.6. Here we present these updates to the structure, and a parametric PyMAPDL model that allows rapid iteration over the different design parameters. Based on this finite element model, we show the preliminary static, modal, and dynamic analyses, that outline the behaviour of the design. The static analysis shows low deformations, which will allow good optical performance once the telescope is pointed at a target. Meanwhile, the modal and dynamic analyses show promising results regarding vibration, pointing and tracking performance, which will enable the telescope to move quickly enough to respond to quickly fading transient events.
The New Robotic Telescope (NRT), the 4-metre, next-generation Liverpool Telescope (LT), will be located on La Palma, Canary Islands. The design and development of the world’s largest robotic telescope, with a slew speed of approximately 10 degrees/second, poses challenges that have resulted in innovative design concepts, including the scheduling algorithms used for optimal science efficiency. We present the latest updates for the NRT project, focusing, in particular, on the status of the observing model which is being adapted from the existing LT model. The catalogue of LT data taken over the past 18 years is being used to model the observing behaviour of the facility and to act as input data for the future NRT scheduling algorithm. This algorithm will combine the existing LT observing model with a new facility Key Science Program, which will conduct rapid-response spectroscopic classifications of a variety of survey targets, transient alerts and variables.
The New Robotic Telescope (NRT) conceptual design has been developed to include an autonomous multi-instrument adaptor at the Cassegrain focal station. The focal station assembly is to consist of a field rotator to compensate the earth rotation, cable wrap, instrument adaptor, support structure, and a fold mirror mechanism to bring the telescope optical beam to the instruments. The design supports the use of multiple instruments around the Acquisition and Guidance box (A&G box) a single instrument port is located at the bottom of the box at the straight through port. The A&G box also includes an autoguider which will be mounted at the side of the box and fed a portion of the optical beam via a small pick off mirror. It will use a field outside that of usable the science field, and has been designed to comprise of off-the-shelf lenses, camera system and lens tubes to minimise cost. The field of view is large enough to conduct ‘blind autoguiding’ at an accuracy of 0.2” with the 4m class telescope. The entire assembly will then be mounted to the M1 cell, forming the bottom part of the telescope tube held between the telescope mount forks. The focal station assembly design will be summarised in this paper.
The NRT is an international collaboration to design and build a leading astronomical facility in the optical and near infrared ranges for the emergent area of time domain astronomy. That relies on the combination of a large collecting area (4 m diameter), quick response (<30 s), and full robotic operation. The system level analysis and trade-offs for assessing image quality, defining optics and optomechanics requirements, integration of both, and expected performance are particular challenging issues for such segmented optical configuration. This contribution presents the methodology developed within the project to produce suitable optical and optomechanical models and measure their performance. This methodology optimizes system level parameter exploration and tradeoffs, quick regeneration of models after possible changes in the design, and integration between optical and mechanical analysis.
The robotic 2-metre Liverpool Telescope (LT), located at Roque de los Muchachos, La Palma, has seen great success in its <15 year lifetime. In particular the facility thrives in time domain astronomy, responding rapidly to triggers from Swift and efficiently conducting a wide variety of science with its intelligent scheduler. The New Robotic Telescope (NRT) will be a 4-metre class, rapid response, autonomous telescope joining the Liverpool Telescope on La Palma in ~2025. The NRT will slew to targets and start observations within 30 seconds of receipt of a trigger, allowing us to observe faint and rapidly fading transient sources that no other optical facility can capture. The NRT will be the world’s largest optical robotic telescope. Its novel, first-generation instrumentation suite will be designed to conduct spectroscopic, polarimetric and photometric observations driven by user requirements.
The New Robotic Telescope is designed to conduct rapid target follow-up within 30 seconds of an ‘alert’ from survey facilities. To achieve this will require a quick settling time requirement for the mount structure and the mirrors. This means the structure shall be designed to be sufficiently rigid to achieve the mirror position within the ‘settle time’ after a quick slew operation. An optimization analysis using the finite element model is developed to conceptually design the mount structure that meets the mechanical and more importantly the NRT science requirements. The main objective of this study is to determine the required locked rotor resonance frequency (LRF) that provides enough rigidity for the telescope dynamic performance while minimizing the structural mass and cost.
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