Radio telescopes play a crucial role in studying the universe, enabling us to explore celestial phenomena and deepen our understanding of astrophysics. This paper proposes the utilization of light-weight foam material integrated with a reflective thin film as an alternative to traditional aluminium panels for radio telescopes. The proposed panel design is aiming for observations in the terahertz frequency range. Here we show preliminary results of the panel in surface accuracy/duration and reflectivity at 345 GHz.
Magnetic field (B-field) is the most controversial factor in molecular clouds for star formation, necessitating further observations. The Star Formation Group at the Chinese University of Hong Kong is currently engaged in the construction of ROGer, Asia's inaugural polarimetry. ROGer will be installed on the 12-meter Greenland Telescope (GLT) and will facilitate the observation of B-field morphology within molecular clouds by utilizing dust thermal emission at 345 GHz. ROGer's polarization module introduces the novel implementation of Martin-Puplett interferometer (MPI) optics, enabling real-time sky noise elimination on the same detector through destructive interference. Two 157-pixel silicon-based aluminum film Microwave Kinetic Inductance Detector (MKID) arrays will be employed to detect the orthogonal signal from the MPI optics. Here we will present the prototype of our novel MPI polarimetry and optics design.
The magnetic field (B-field) plays a crucial role in the process of star formation. To observe molecular cloud B-fields, astronomers rely on submm dust emission observation. This is because dust grains in molecular clouds align with B-field. However, polarized signals are obscured by the intense non-polarized emission from the Earth’s atmosphere. To overcome this challenge, sophisticated instruments (polarimeters) and strategic observation methods are necessary. However, these tools have not undergone fundamental advancements for two decades because new technologies can only be tested on remote and rare submm telescopes. Thus, we are motivated to develop the Sky Noise Simulator (SNoS). Here we present how we use SNoS to produce a beam that consists of predominantly non-linearly polarized noise and a faint linearly polarized signal. This combined beam is then directed into the instrument under test (IUT). With SNoS, polarimeters can be conveniently tested in the laboratory without moving to telescopes.
SCUBA-2/POL-2 has been the most productive instrument at JCMT since it’s fully commissioned in 2011 September, and it’s constantly oversubscribed during the call-for-proposals by a factor of 3 to 5. The proposed new 850μm instrument will feature 7272 state-of-the-art Microwave Kinetic Inductance Detectors (MKIDs) operated below 100 mK, fully utilizing the JCMT’s 12 arcmin Field of View (FoV), thus have all the capabilities of SCUBA-2 at 850 μm, yet will map an order of magnitude faster. The new instrument will be incorporated with intrinsic polarization measurement capability which is 3636 pixels. Mapping the 850 μm polarization will be improved by a factor of at least 20.
KEYWORDS: Telescopes, Control systems, Polarimetry, Control systems design, Software development, Interfaces, Human-machine interfaces, Telecommunications, Optical instrument design, Data communications
The ASTE Polarimeter (APol), developed by Dr. Li at the Chinese University of Hong Kong (CUHK), presented a simple but innovative approach to carry out polarimetric measurements using ASTE Telescope’s TES camera. Our group at Universidad Austral de Chile (UACh) has collaborated in the project since its early stages and was assigned with the task of developing the control software for the instrument. The software has been developed also keeping the simplicity concept in mind. All its functionality has been separated in simple modules which are in charge of well defined tasks. The interfaces between the modules follow the design of modern applications and are based on well defined standards, such as those used by internet applications. The instrument has also the opportunity to be tested on the JCMT Telescope, and it is going to be used as the base design for a polarimeter in the future Leighton Chajnantor Telescope (LCT). Therefore, there is a requirement that the control software should be flexible enough to interface with at least these three telescopes, all of which run very different control software systems. This paper presents the design and implementation of APol’s control software, as well as some results of laboratory tests of the instrument.
The Atacama Submillimeter Telescope Experiment (ASTE) 10m aperture telescope has a multicolor camera based on a spiderweb absorber Transition Edge Sensor (TES) bolometer array. We developed a fore-optics module – ‘APol’, to convert 256 pixels of the TES camera into a sensitive imaging polarimeter at 350 ± 25 GHz. We used the simple half-wave plate - wire grid - camera design in APol, and it can cover 7’.5 FOV of ASTE. Here we describe the detailed optical design of APol and present result of the preliminary test carried out with the same optical system and camera at National Astronomical Observatory of Japan (NAOJ) laboratory.
SHARC-II is a 32 × 12 pixel submillimeter camera that is used with the ten-meter diameter Caltech Submillimeter
Observatory (CSO) on Mauna Kea. This camera can be operated at either 350 or 450 microns. We developed a module
that is installed at the CSO Nasmyth focus in order to convert SHARC-II into a sensitive imaging polarimeter, which we
refer to as "SHARP". SHARP splits the incident beam into two orthogonal polarized beams that are then re-imaged onto
different halves of the SHARC-II bolometer array. When this removable polarimetry module is in use, SHARC-II
becomes a dual-beam 12 × 12 pixel polarimeter. Sky noise is a significant source of error for submillimeter continuum
observations. Because SHARP will simultaneously observe two orthogonal polarization components, we are able to
eliminate or greatly reduce this source of error. Here we describe the design of SHARP and report preliminary results of
tests and observations carried out during our first two runs at CSO in August 2005 and January 2006.
The Submillimeter High Angular Resolution Camera II (SHARC-II) is a 32 x 12 pixel submillimeter camera that is used with the ten-meter diameter Caltech Submillimeter Observatory (CSO) on Mauna Kea. SHARC-II can be operated at either 350 or 450 microns. We are developing an optics module that we will install at a position between the SHARC-II camera and the focus of the CSO's secondary mirror. With our module installed, SHARC-II will be converted into a sensitive imaging polarimeter. The basic idea is that the module will split the incident beam coming from the secondary into two orthogonally polarized beams which are then re-imaged onto opposite ends of the “long and skinny” SHARC-II bolometer array. When this removable polarimetry module is in use, SHARC-II becomes a dual-polarization 12 x 12 pixel polarimeter. (The central 12 x 8 pixels of the SHARC-II array will remain unused.) Sky noise is a significant source of error for submillimeter continuum observations. Because our polarimetry module will allow simultaneous observation of two orthogonal polarization components, we will be able to eliminate or greatly reduce this source of error. Our optical design will include a rotating half-wave plate as well as a cold load to terminate the unused polarization components.
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