Infrared instruments for astronomy require many bearings for motion that must move in cryogenic conditions. There are poor and expensive options for this, and the companies with qualified bearings only supply after a long time. To attend these constrains, the Instituto de Astrofísica de Canarias (IAC) started to develop a procedure to upgrade commercial bearing to operate to cryogenic conditions.
The initial attempts involved sprinkling molybdenum disulfide (MoS2) inside the bearing without disassembling it after cleaning. However, this method prevented uniform lubrication, leading to potential failures. The IAC mechanical team diligently refined the procedure, which included disassembling the bearings and replacing the cage by a technical polyamide cage.
This innovative approach significantly enhances efficiency; however, it comes at a higher cost due to high price of some technical polyamides such as Vespel. Additional research and testing have demonstrated that the pre-lubrication the bearing races with MoS2 significantly increases bearing life, although it involves a laborious process.
In recent years our focus has been on exploring more cost-effective material and how to improve bearing life.
This presentation discusses these techniques and the selected material for bearing preparation and presents the results of the latest cryogenic temperature life tests conducted on the produced bearings, along with the conclusions reached.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. 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.
The core of HARMONI is the Integral Field Spectrograph (IFS) which is composed of different subsystems including the IFS Pre-Optics (IPO). The IPO main objective is to take light from the focal plane relay system and reformat and condition it to be a suitable input for the rest of the instrument. The IPO in HARMONI includes the IFS Pre-Optics Fast Shutter (POFS), a mechanical cryogenic fast shutter which will be used with both the visible and infrared detectors. This mechanism has been designed to be fast and reliable and its design has already passed the Critical Design Review (CDR) but specific issues that require further analysis have been identified. The functioning of this element is a critical part in HARMONI and, consequently, a prototype has been used to analyze possible improvements in the CDR design and to perform extensive testing before the Final Design Review (FDR).
In this work we present the design of the IFS Pre-Optics Fast Shutter and the test results obtained with the prototype developed at the facilities of the Instituto de Astrofísica de Canarias (IAC).
HARMONI is the high angular optical and near-IR integral field spectrograph (IFS) for the ELT. The instrument covers a large spectral range from 470 to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60 to 4mas. A workhorse instrument designed to operate in two Adaptive Optics modes - Single-Conjugate Adaptive Optics (SCAO, including a High Contrast capability) and Laser Tomography Adaptive Optics (LTAO) - or without adaptive optics. HARMONI project is now finishing phase C, ready for Final Design Reviews of all subsystems.
The Instrument Pre-Optics (IPO) is one of the HARMONI subsystems. It distributes the telescope light received from the adaptative optics systems. The main objective of the IPO is to format the field for the selected spatial scales feeding the Integral Field Unit (IFU). IPO is under the responsibility of the Institute of Astrophysics of the Canary Islands (IAC). This optical subsystem implements 30 Opto-mechanical mounts working at cryogenic temperatures. The mounts may be classified into two types based on the features of the optics they support: (1) Sprung Kinematic Mount (SKM) for flat mirrors, and (2) Thermally Compensated Kinematic Sprung Mounts (TCKSM) for power mirrors (toroidal mirrors, offaxis parabolas, and cameras). Designed to maintain optical alignment at cryogenic temperatures, the mounts maintain optical surface deformation within the limits specified by the error budget, ensuring compliance with requirements even worst-case scenarios.
This work describes the verification tests performed to the engineering models of the Opto-mechanical mounts of the IPO to validate compliance with the sub-system optical and mechanical requirements at both room and cryogenic temperatures.
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.
HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT’s diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT’s unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, and provide a summary of the instrument’s design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.
HARMONI is the first light visible and near-IR integral field spectrograph for the Extremely Large Telescope (ELT). This instrument covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. The Pre-Optics (sub-system under the responsibility of the IAC) contains five mechanisms working at cryogenic temperatures. Three types of mechanisms are needed to provide full functionality: wheels (2), turrets (2) and shutter (1). The wheels and turrets, supported by a series of radial and axial bearings, are driven by stepper motors through a system of gears that provide mechanical reduction. In addition, the focal plane mask wheel has a detent system to improve repeatability to within +/- 2.5 microns. Finally, the shutter consists in two masks with three clover shape blades mounted on a stepper motors. The work describes the main IPO mechanisms requirements and the design developed for every module. We also present some of the prototypes developed to proof the concepts adopted in the design..
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