Degree Field Of View Research Articles

The Maunakea Spectroscopic Explorer: Thousands of fibers, infinite possibilities

The Maunakea Spectroscopic Explorer (MSE) is a massively multiplexed spectroscopic survey facility that will replace the Canada–France–Hawai'i Telescope over the next two decades. This 12.5‐m telescope, with its 1.5 square degree field of view, will observe 18,000–20,000 astronomical targets in every pointing from 0.36 to 1.80 m at low/moderate resolution (R3,000, 6,000) and from 0.36 to 0.90 m at high resolution (R30,000). Parallel positioning of all fibers in the field will occur, providing simultaneous full‐field coverage for both resolution modes. Unveiling the composition and dynamics of the faint Universe, MSE will impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe, including (i) the ultimate Gaia follow‐up facility for understanding the chemistry and dynamics of the distant Milky Way, including the distant halo at high spectral resolution, (ii) the unparalleled study of galaxy formation and evolution at cosmic noon, (iii) the determination of the neutrino mass, and (iv) the generation of insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. Initially, CFHT will build a Pathfinder instrument to fast‐track the development of MSE technology while providing multi‐object and IFU spectroscopic capability.

Preview the Products on Display at Display Week 2023

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Aberration analysis of a projection-type CGH display with an expanded FOV based on the HOE screen.

This paper proposed a holographic optical element as a see-through screen for the computer-generated hologram projection system with 3D images. The proposed holographic screen consisted of a linear grating and a lens phase. The linear grating is used to redirect the information light and guide information into the observer's eye and achieve the see-through function. The lens phase is used to magnify the field of view of the holographic projection system. The aberration caused by the screen was analyzed in this paper and the aberration can be pre-corrected in the hologram calculation algorithm. Finally, the proposed system achieved 20.3 by 14.3 degrees field of view at 532 nm laser based on the spatial light modulator with 6.4 µm pixels.

LAMOST MRS-N Observation of the W80 Region

The spectral observations and analysis for the W80 region are presented by using the data of Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). A total of 2982 high-quality nebular spectra have been obtained in the 20 square degree field of view which covers the W80 complex, and the largest sample of spectral data has been established for the first time. The relative intensities, radial velocities (RVs), and full widths at half maximum (FWHMs) are measured with the high spectral resolution of LAMOST MRS-N, for Hα λ6563 Å, [N ii] λλ6548 Å, 6584 Å, and [S ii] λλ6716 Å, 6731 Å emission lines. In the field of view of the whole W80 region, the strongest line emissions are found to be consistent with the bright nebulae NGC 7000, IC 5070, and LBN 391, and weak line emissions also exist in the Middle Region, where no bright nebulae are detected by the wide-band optical observations. The large-scale spectral observations of the W80 region reveal the systematic spatial variations of RVs and FWHMs, and several unique structural features. A “curved feature” to the east of NGC 7000, and a “jet feature” to the west of LBN 391 are detected to be showing larger RVs. A “wider FWHM region” is identified in the eastern part of NGC 7000. The variations of [S ii]/Hα ratios display a gradient from southwest to northeast in the NGC 7000 region, and manifest a ring shape around the “W80 bubble” ionized by an O-type star in L935. Further spectral and multi-band observations are guaranteed to investigate in detail the structural features.

The Scientific Impact of the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) for Solar System Science

Vera C. Rubin Observatory will be a key facility for small body science in planetary astronomy over the next decade. It will carry out the Legacy Survey of Space and Time (LSST), observing the sky repeatedly in u, g, r, i, z, and y over the course of ten years using a 6.5 m effective diameter telescope with a 9.6 square degree field of view, reaching approximately r = 24.5 mag (5-{\sigma} depth) per visit. The resulting dataset will provide extraordinary opportunities for both discovery and characterization of large numbers (10--100 times more than currently known) of small solar system bodies, furthering studies of planetary formation and evolution. This white paper summarizes some of the expected science from the ten years of LSST, and emphasizes that the planetary astronomy community should remain invested in the path of Rubin Observatory once the LSST is complete.

The Display Week 2021 Symposium Preview

The Display Week 2021 Symposium Preview

Polysilicon Grating Switches for LiDAR

Novel polysilicon grating switches are demonstrated, consisting of an optical grating suspended on a moving platform above a waveguide. Electrostatic attraction pulls the grating into close proximity to the waveguide, ejecting light out of the waveguide plane. The switches move only 0.9 to 1.4 $\mu \text{m}$ , and have MHz mechanical resonant frequencies, making them robust to mechanical vibration and shock. These switches enable a new mode of LiDAR imaging; by creating a focal plane array of switches, and coupling it with a standard camera lens, the LiDAR beam can be scanned across the scene with high speed and arbitrary pattern. Both time of flight and coherent ranging techniques are compatible with this approach. We have demonstrated a $10\times 10$ pixel array of these switches in a LiDAR system, collecting 3D raging data at up to 15 meters away and 5 frames per second, over a 1 degree field of view with 0.1 degree resolution. Additionally, we have shown the switches to be robust, efficient, and reliable, actuating at 15 Volts, with speeds faster than $4~\mu \text{s}$ , for over 9 billion cycles without degradation or failure. [2020-0132]

Multi-Panel Sparse Base Station Design With Physical Antenna Effects in Massive MU-MIMO

A novel base station antenna (BSA) configuration is presented to mitigate degrading physical antenna effects in massive multiple-input multiple-output (MIMO) systems, while minimizing implementation complexities. Instead of using a commonly considered single antenna panel comprising of many elements covering a wide field-of-view (FOV) of 120 degrees, L tilted panels are used employing L times fewer elements and L times smaller FOV per panel. The spatial resolution of each panel is enhanced by employing sparse arrays with suppressed (grating-lobe) radiation outside its corresponding FOV. Therefore, more directive antenna elements can be deployed in each panel to compensate for the effective isotropic radiated power (EIRP) reduction. While sectorisation reduces the antenna gain variation in 120 degrees FOV, cooperation among multiple panels in downlink beamforming is seen to be capable of inter-panel interference suppression for sum-rate enhancement. A network model is used as a multi-user (MU) MIMO simulator incorporating both antenna and channel effects. It is shown that when the number of base station antennas is ten times the number of users, the average downlink sum-rate in pure line-of-sight (LOS), rich and poor multipath environments is increased up to 60.2%, 23% and 11.1%, respectively, by multi-panel sparse arrays applying zero-forcing (ZF) precoding.

ThinVR: Heterogeneous microlens arrays for compact, 180 degree FOV VR near-eye displays.

Today's Virtual Reality (VR) displays are dramatically better than the head-worn displays offered 30 years ago, but today's displays remain nearly as bulky as their predecessors in the 1980's. Also, almost all consumer VR displays today provide 90-110 degrees field of view (FOV), which is much smaller than the human visual system's FOV which extends beyond 180 degrees horizontally. In this paper, we propose ThinVR as a new approach to simultaneously address the bulk and limited FOV of head-worn VR displays. ThinVR enables a head-worn VR display to provide 180 degrees horizontal FOV in a thin, compact form factor. Our approach is to replace traditional large optics with a curved microlens array of custom-designed heterogeneous lenslets and place these in front of a curved display. We found that heterogeneous optics were crucial to make this approach work, since over a wide FOV, many lenslets are viewed off the central axis. We developed a custom optimizer for designing custom heterogeneous lenslets to ensure a sufficient eyebox while reducing distortions. The contribution includes an analysis of the design space for curved microlens arrays, implementation of physical prototypes, and an assessment of the image quality, eyebox, FOV, reduction in volume and pupil swim distortion. To our knowledge, this is the first work to demonstrate and analyze the potential for curved, heterogeneous microlens arrays to enable compact, wide FOV head-worn VR displays.

Retinal projection type lightguide-based near-eye display with switchable viewpoints.

We present a retinal-projection-based near-eye display with switchable multiple viewpoints by polarization-multiplexing. Active switching of viewpoints is provided by the polarization grating, multiplexed holographic optical elements and polarization-dependent eyepiece lens that can generate one of the dual-divided focus groups according to the pupil position. The lightguide-combined optical devices have a potential to enable a wide field of view (FOV) and short eye relief with compact form factor. Our proposed system can support a pupil movement with an extended eyebox and mitigate image problem caused by duplicated viewpoints. We discuss the optical design for guiding system and demonstrate that proof-of-concept system provides all-in-focus images with 37 degrees FOV and 16 mm eyebox in horizontal direction.

Large Field of View Cooperative Infrared and Visible Spectral Sensor for Visual Odometry

Thermal images produced by the long-wavelength infrared (LWIR) camera are robust and independent from environmental illumination change. They can help the standard visible light camera working under the complicated environmental condition. Breaking through the traditional stereo multi-spectral sensor consisting of a visible-light camera and a LWIR camera, a novel architecture of large field of view (FOV) cooperated infrared and visible spectral sensor for visual odometry is proposed. The novel sensor is equipped with two visible cameras, four infrared cameras covering 120 degrees FOV in horizontal under both bands. Distribution of cameras and related peripheral devices are specifically designed which makes the sensor's volume less than 100 cm (length) × 10 cm (height) × 10 cm (width). The sensor's cameras calibration, distortion correction and measurement principle are elaborated. Feature-based method for visible and multi-windowed optimization-based image alignment for infrared is designed for the visual odometer based on the different imaging mechanism and distribution of cameras in the sensor. The frames and estimated poses management from both bands are proposed. Moreover, all proposed methodologies can be implemented in the sensor's embedded processor. The electrical power consumption is only 12W. Experiments of the sensor's evaluation are performed, experimental results show that large FOV cooperated multi-spectral cameras can efficiently improve the robustness of visual odometry. The real-time performance of the sensor is higher than 10fps with disparity map construction under both bands.

Weak lensing in the Horizon-AGN simulation lightcone

Context. Accurate model predictions including the physics of baryons are required to make the most of the upcoming large cosmological surveys devoted to gravitational lensing. The advent of hydrodynamical cosmological simulations enables such predictions on sufficiently sizeable volumes. Aims. Lensing quantities (deflection, shear, convergence) and their statistics (convergence power spectrum, shear correlation functions, galaxy-galaxy lensing) are computed in the past lightcone built in the Horizon-AGN hydrodynamical cosmological simulation, which implements our best knowledge on baryonic physics at the galaxy scale in order to mimic galaxy populations over cosmic time. Methods. Lensing quantities are generated over a one square degree field of view by performing multiple-lens plane ray-tracing through the lightcone, taking full advantage of the 1 kpc resolution and splitting the line of sight over 500 planes all the way to redshift z ∼ 7. Two methods are explored (standard projection of particles with adaptive smoothing, and integration of the acceleration field) to ensure a good implementation. The focus is on small scales where baryons matter most. Results. Standard cosmic shear statistics are affected at the 10% level by the baryonic component for angular scales below a few arcminutes. The galaxy-galaxy lensing signal, or galaxy-shear correlation function, is consistent with measurements for the redshift z ∼ 0.5 massive galaxy population. At higher redshift z ≳ 1, the effect of magnification bias on this correlation is relevant for separations greater than 1 Mpc. Conclusions. This work is pivotal for all current and upcoming weak-lensing surveys and represents a first step towards building a full end-to-end generation of lensed mock images from large cosmological hydrodynamical simulations.

Design, fabrication and space suitability tests of wide field of view, ultra-compact, and high resolution telescope for space application.

We report on the design, manufacture, and testing of an ultra-compact telescope for 16 unit (16U) CubeSats for Earth and space observation. This telescope provides 1 arcsec resolution at a 2.9 degree field of view. Dimensions are optimized to 230 × 230 × 330mm3 with a mass of less than 6kg including support structure. Our catadioptric 5-element design consists of a full-aperture corrector, a Mangin primary mirror (PM), a secondary mirror (SM), and a 2-lens field corrector. The focal length is 745mm, and squared-circular aperture has an equivalent diameter of 241mm. The designed modulation transfer function (MTF) is 0.275 for the entire unit including baffles at a Nyquist frequency of 161 cycles/mm for the 450-800nm band. As one of the distinguishing features of our state-of-the-art design, all optical surfaces are spherical to simplify adjustment. For the best thermal stability, all optical elements are produced from fused silica. We describe the details of design, adjustment, and laboratory performance tests for space environments in accordance with the requirements for in-orbit operation onboard Earth-observation micro-satellites to be launched in 2018.

Methods for the performance enhancement and the error characterization of large diameter ground-based diffractive telescopes.

This paper is devoted to the improvement of ground-based telescopes based on diffractive primary lenses, which provide larger aperture and relaxed surface tolerance compared to non-diffractive telescopes. We performed two different studies devised to thoroughly characterize and improve the performance of ground-based diffractive telescopes. On the one hand, we experimentally validated the suitability of the stitching error theory, useful to characterize the error performance of subaperture diffractive telescopes. On the other hand, we proposed a novel ground-based telescope incorporated in a Cassegrain architecture, leading to a telescope with enhanced performance. To test the stitching error theory, a 300 mm diameter, 2000 mm focal length transmissive stitching diffractive telescope, based on a three-belt subaperture primary lens, was designed and implemented. The telescope achieves a 78 cy/mm resolution within 0.15 degree field of view while the working wavelength ranges from 582.8 nm to 682.8 nm without any stitching error. However, the long optical track (35.49 m) introduces air turbulence that reduces the final images contrast in the ground-based test. To enhance this result, a same diameter compacted Cassegrain ground-based diffractive (CGD) telescope with the total track distance of 1.267 m, was implemented within the same wavelength. The ground-based CGD telescope provides higher resolution and better contrast than the transmissive configuration. Star and resolution tests were experimentally performed to compare the CGD and the transmissive configurations, providing the suitability of the proposed ground-based CGD telescope.

MIGHTEE: The MeerKAT International GHz Tiered Extragalactic Exploration

The MeerKAT telescope is the precursor of the Square Kilometre Array mid-frequency dish array to be deployed later this decade on the African continent. MIGHTEE is one of the MeerKAT large survey projects designed to pathfind SKA key science in cosmology and galaxy evolution. Through a tiered radio continuum deep imaging project including several fields totaling 20 square degrees to microJy sensitivities and an ultra-deep image of a single 1 square degree field of view, MIGHTEE will explore dark matter and large scale structure, the evolution of galaxies, including AGN activity and star formation as a function of cosmic time and environment, the emergence and evolution of magnetic fields in galaxies, and the magnetic counter part to large scale structure of the universe.

다수의 카메라를 이용한 고해상도 360도 동영상 생성 시스템

This paper develops a 360 degree video system using multiple off-the-shelf webcams and a set of embedded boards. Existing 360 degree cameras have shortcomings that they do not support real-time video generation since recorded videos should be copied to computers or smartphones which then provide stitching. Another shortcoming is that wide FoV(Field of View) cameras are not able to provide sufficiently high resolution. Moreover, resulting images are visually distorted bending straight lines. By employing an array of 65 degree FoV webcams, we were able to generate videos on the spot and achieve over 6K resolution with much less distortion. We describe the configuration and algorithms of the proposed system. The performance evaluation results of our early stage prototype system are presented.

Deep observations of the Super-CLASS supercluster at 325 MHz with the GMRT: the low-frequency source catalogue

We present the results of 325 MHz GMRT observations of a super-cluster field, known to contain five Abell clusters at redshift $z \sim 0.2$. We achieve a nominal sensitivity of $34\,\mu$Jy beam$^{-1}$ toward the phase centre. We compile a catalogue of 3257 sources with flux densities in the range $183\,\mu\rm{Jy}\,-\,1.5\,\rm{Jy}$ within the entire $\sim 6.5$ square degree field of view. Subsequently, we use available survey data at other frequencies to derive the spectral index distribution for a sub-sample of these sources, recovering two distinct populations -- a dominant population which exhibit spectral index trends typical of steep-spectrum synchrotron emission, and a smaller population of sources with typically flat or rising spectra. We identify a number of sources with ultra-steep spectra or rising spectra for further analysis, finding two candidate high-redshift radio galaxies and three gigahertz-peaked-spectrum radio sources. Finally, we derive the Euclidean-normalised differential source counts using the catalogue compiled in this work, for sources with flux densities in excess of $223 \, \mu$Jy. Our differential source counts are consistent with both previous observations at this frequency and models of the low-frequency source population. These represent the deepest source counts yet derived at 325 MHz. Our source counts exhibit the well-known flattening at mJy flux densities, consistent with an emerging population of star-forming galaxies; we also find marginal evidence of a downturn at flux densities below $308 \, \mu$Jy, a feature so far only seen at 1.4 GHz.

An Insect Eye Inspired Miniaturized Multi-Camera System for Endoscopic Imaging.

In this work, we present a miniaturized high definition vision system inspired by insect eyes, with a distributed illumination method, which can work in dark environments for proximity imaging applications such as endoscopy. Our approach is based on modeling biological systems with off-the-shelf miniaturized cameras combined with digital circuit design for real time image processing. We built a 5 mm radius hemispherical compound eye, imaging a 180°×180° degrees field of view while providing more than 1.1 megapixels (emulated ommatidias) as real-time video with an inter-ommatidial angle ∆ϕ = 0.5° at 18 mm radial distance. We made an FPGA implementation of the image processing system which is capable of generating 25 fps video with 1080 × 1080 pixel resolution at a 120 MHz processing clock frequency. When compared to similar size insect eye mimicking systems in literature, the system proposed in this paper features 1000 × resolution increase. To the best of our knowledge, this is the first time that a compound eye with built-in illumination idea is reported. We are offering our miniaturized imaging system for endoscopic applications like colonoscopy or laparoscopic surgery where there is a need for large field of view high definition imagery. For that purpose we tested our system inside a human colon model. We also present the resulting images and videos from the human colon model in this paper.

Outskirts of Local Group Dwarf Galaxies Revealed by Subaru Hyper Suprime-Cam

AbstractLocal Group galaxies are important targets since their stellar populations can be resolved, and their properties can be investigated in detail with the help of stellar evolutionary models. The newly-built instrument for the 8.2m Subaru Telescope, Hyper Suprime-Cam (HSC), which has a 1 Giga pixel CCD camera with 1.5 degrees field of view, is the best instrument for observing Local Group galaxies. We have carried out a survey for Local Group dwarf galaxies using HSC aiming to shed light on the outskirts of these galaxies. The survey covers target galaxies out beyond the tidal radii down to a depth unexplored by previous surveys. Thanks to the high spatial resolution and high sensitivity provided by the Subaru Telescope, we are able to investigate properties such as spatial distribution and stellar population from the very center of galaxies to the outskirts. In this article, I will show results for the dwarf irregular galaxy NGC 6822 and the dwarf spheroidal galaxy Ursa Minor.

Wide-field broad-band radio imaging with phased array feeds: a pilot multi-epoch continuum survey with ASKAP-BETA

The Boolardy Engineering Test Array is a 6 x 12 m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These facilitate rapid wide-area imaging via the deployment of simultaneous multiple beams within a 30 square degree field of view. By cycling the array through 12 interleaved pointing positions and using 9 digitally formed beams we effectively mimic a traditional 1 hour x 108 pointing survey, covering 150 square degrees over 711 - 1015 MHz in 12 hours of observing time. Three such observations were executed over the course of a week. We verify the full bandwidth continuum imaging performance and stability of the system via self-consistency checks and comparisons to existing radio data. The combined three epoch image has arcminute resolution and a 1-sigma thermal noise level of 375 micro-Jy per beam, although the effective noise is a factor 3 higher due to residual sidelobe confusion. From this we derive a catalogue of 3,722 discrete radio components, using the 35 percent fractional bandwidth to measure in-band spectral indices for 1,037 of them. A search for transient events reveals one significantly variable source within the survey area. The survey covers approximately two-thirds of the Spitzer South Pole Telescope Deep Field. This pilot project demonstrates the viability and potential of using PAFs to rapidly and accurately survey the sky at radio wavelengths.