The paper reports on recent progress in electro-optical and photonics developments at the Canadian Space Agency / Space Technologies / Optical Instrumentation Group. Technology R&D projects in active sensing, lasers and Optical Inter-Satellite Links (OISL) are underway both in-house and in contracting out to Canadian industry. In-house projects are concerned with: - Research and development of a novel all-optical tracking technique for OISL using non-linear optical concepts; these include development of a high-speed communication interface and search for efficient non-linear / optical / laser / light-weight materials to work in the space environment. - Development of space vision systems - an eye-safe laser scanner for 3D-tracking and imaging, and a stereo vision system for object recognition and pose tracking linked to a robotic test-bed (in cooperation with CSA Spacecraft Engineering / Robotics Group); CSA has supported the development of a laser vision system that was demonstrated on a recent Shuttle flight.
WFIRST-AFTA is the NASA’s highest ranked astrophysics mission for the next decade that was identified in the New
World, New Horizon survey. The mission scientific drivers correspond to some of the deep questions identified in the
Canadian LRP2010, and are also of great interest for the Canadian scientists. Given that there is also a great interest in
having an international collaboration in this mission, the Canadian Space Agency awarded two contracts to study a
Canadian participation in the mission, one related to each instrument. This paper presents a summary of the technical
contributions that were considered for a Canadian contribution to the coronagraph and wide field instruments.
Canada became actively engaged in space astronomy in the 1990s by contributing two fine guidance sensors to the FUSE Far-UV mission (NASA 1999-2008). In the same period, Canada contributed to ODIN’s infrared instrument (ESA 2001-2006) and correlators for VSOP (JAXA 1997-2005). In early 2000, Canada developed its own space telescope, Micro-variability and Observations of STars (MOST), a 15-cm telescope on a microsatellite, operating since 2003, and more recently contributed to the realization of the BRITE nanosatellites constellation. Canada also provided hardware to the European Space Agency’s Herschel HIFI instrument and simulators to the SPIRE instrument and data analysis tools for Planck. More recently the Canadian Space Agency (CSA) delivered detector units for the UVIT instrument on board the Indian Space Research Organisation’s (ISRO) ASTROSAT. The CSA’s most important contribution to a space astronomy mission to date is the Fine Guidance Senor (FGS) and Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument to NASA’s James Webb Space Telescope. The CSA is currently building the laser metrology system for JAXA’s ASTRO-H hard X-ray telescope. Canadian astronomers contributed to several high profile stratospheric balloon projects investigating the CMB and the CSA recently established a balloon launch facility. As expressed in Canada’s new Space Policy Framework announced in February 2014, Canada remains committed to future space exploration endeavors. The policy aims at ensure that Canada is a sought-after partner in the international space exploration missions that serve Canada’s national interests; and continuing to invest in the development of Canadian contributions in the form of advanced systems and optical instruments. In the longer term, through consultations and in keeping the Canadian astronomical community’s proposed Long Range Plan, the CSA is exploring possibilities to contributions to important missions such as WFIRST, SPICA and Athena and in other areas, by initiating concept and pre-mission studies and enabling technology developments. These reflect the following scientific priorities identified: dark energy and the accelerating universe, addressed by large survey missions; high-energy astrophysics, which includes UV and X-ray missions; and the understanding of star formation and proto-planetary systems and to begin characterizing exoplanets, mainly by infra-red space observatories.
EMCCDs are capable of MHz pixel rate whilst maintaining sub-electron readout noise. Tens of frames per second are common place for large and medium EMCCD formats (1k×1k, 512×512), while smaller formats can reach hundreds and even thousand of frames per second. For applications where speed is a key factor, overclocked EMCCD were used at or beyond the manufacturer’s specifications. Very few data were published on the impacts of high speed clocking of EMCCDs, either vertically or horizontally. This paper presents characterization results of EMCCDs clocked at high speed.
The rapid proliferation of Electron Multiplying Charge Coupled Devices (EMCCDs) in recent years has revolutionized
low light imaging applications. EMCCDs in particular show promise to enable the construction of versatile space
astronomy instruments while space-based observations enable unique capabilities such as high-speed accurate
photometry due to reduced sky background and the absence of atmospheric scintillation. The Canadian Space Agency is
supporting innovation in EMCCD technology by increasing its Technology Readiness Level (TRL) aimed at reducing
risk, cost, size and development time of instruments for future space missions. This paper will describe the advantages of
EMCCDs compared to alternative low light imaging technologies. We will discuss the specific issues associated with
using EMCCDs for high-speed photon counting applications in astronomy. We will show that a careful design provided
by the CCD Controller for Counting Photons (CCCP) makes it possible to operate the EMCCD devices at rates in excess
of 10 MHz, and that levels of clock induced charge and dark current are dramatically lower than those experienced with
commercial cameras. The results of laboratory characterization and examples of astronomical images obtained with
EMCCD cameras will be presented. Issues of radiation tolerance, charge transfer efficiency at low signal levels and life
time effects on the electron-multiplication gain will be discussed in the context of potential space applications.
EMCCDs are capable of extreme low light imaging thanks to sub-electron read-out noise, enabling single-photon counting.
The characterization of e2v's CCD60 (128 x 128), CCD97 (512 x 512) and CCD201-20 (1024 x 1024) using a controller
optimized for the driving of EMCCDs at a high (≥10 MHz) pixel rate per output with < 0.002 e- total background signal.
Using the CCD Controller for Counting Photons (CCCP), the horizontal and vertical CIC, dark current and EM gain
stability are characterized.
The Near Earth Object Surveillance Satellite (NEOSSat) is a small satellite dedicated to finding near Earth asteroids. Its
surveying strategy consists of imaging areas of the sky to low solar elongation, while in a sun synchronous polar orbit
(dawn-dusk). A high performance baffle will control stray light mainly due to Earth shine. Observation scenarios
require solar shielding down to 45 degree solar elongation over a wide range of ecliptic latitudes. In order to detect the
faintest objects (approx 20th v mag) given a 15 cm telescope and CCD detection system, background from stray light is a
critical operational concern. The required attenuation is in the order of 10-12. The requirement was verified by analyses;
testing was not attempted because the level of attenuation is difficult to measure reliably. We report consistent results of
stray light optical modelling from two independent analyses. Launch is expected for late 2012.
The Cosmological Advanced Survey Telescope for Optical and UV Research (CASTOR) is a proposed CSA
mission that would make a unique, powerful, and lasting contribution to astrophysics by providing panoramic,
high-resolution imaging in the UV/optical (0.15 - 0.55 μm) spectral region. This versatile `smallSAT'-class
mission would far surpass any ground-based optical telescope in terms of angular resolution, and would provide
ultra-deep imaging in three broad lters to supplement longer-wavelength data from planned international dark
energy missions (Euclid, WFIRST) as well as from the ground-based Large Synoptic Survey Telescope (LSST).
Combining the largest focal plane ever
own in space, with an innovative optical design that delivers HST-quality
images over a eld two orders of magnitude larger than Hubble Space Telescope (HST), CASTOR would image
about 1/8th of the sky to a (u-band) depth ~1 magnitude fainter than will be possible with LSST even after a
decade of operations. No planned or proposed astronomical facility would exceed CASTOR in its potential for
discovery at these wavelengths.
The Hard X-ray Telescopes on Astro-H have a 12-meter focal length. In order to achieve this long focal length and still fit compactly in the H-IIA launch fairing, the detectors are mounted at the end of an extendable optical bench that will be deployed in orbit. Once in operations, the spacecraft will experience distortions primarily due to thermal fluctuations in low-earth orbit and it is important that thte misalignment between the telescopes and instruments is accurately measured. The Canadian Astro-H Metrology System (CAMS) is a laser alignment system that will measure optical alignment deviations. The CAMS is compact, consumes little power, and is stable over a wide temperature range. The system will be used to measure lateral (X/Y) displacement as well as rotational shifts in the optical bench. In addition, the CAMS data can be used to enhance the quality of the hard X-ray images that will have been degraded by the deviations.
Although there is some success in finding Near Earth asteroids from ground-based telescopes, there is a marked
advantage in performing the search from space. The ability to search at closer elongations from the sun and
being able to observe continuously, allowing quick revisits of new asteroids, are some of the unique benefits of
a space platform. The Canadian Space Agency (CSA) together with Defense Research and Development
Canada (DRDC) are planning a micro-satellite platform with a 15 cm telescope dedicated for near space
surveillance. The NEOSSat (Near Earth Object Surveillance) spacecraft is expected to be able to detect 20 v
magnitude objects with a 100 sec exposure, with a 0.85 deg FOV, on a 1024x1024 CCD, and sub arcsec
pointing stability. For detection of NEO small bodies, it will be able to search an area from 45 degrees solar
elongation and approximately 40 degrees north to south degrees in elevation. The observation strategy will be
optimized to find as many asteroids as possible, based on recent models of asteroid population. Ground based
telescopes will also be used to complement follow-ups for orbit determination when possible. The microsatellite
is based on the CSA very successful MOST micro-satellite, operating since 2003. Baselined for launch
in 2010, the NEOSSat is a shared project with DRDC to demonstrate the technology of an inexpensive space
platform to detect High Earth Orbit (HEOSS) earth-orbiting satellites and debris.
A wide-field low-resolution multi-object optical spectrograph suitable for a 30-m F/15 telescope is described. The effort to build a 30-m class telescope is gaining momentum. Many science cases for such a telescope make the need for a wide-field seeing-limited spectrograph a high priority. Our concept comprises four identical instruments placed symmetrically around the optical axis of the telescope, this allows smaller dimensions for the spectrographs and their components. Each instrument is placed in one quadrant of the telescope focal plane; a space at the center of the field is free for other instrumentation. Using a dichroic beam-splitter each instrument feeds a "red" and "blue" camera. The total field is 81 square arcmin, the wavelength range covers simultaneously 310 nm to 1000 nm and the spectral resolution (R) is 300 to 5000. The instruments are designed for vertical mounting at a Nasmyth focus to avoid gravity vector changes and reducing mechanical flexure problems during observation. The layout also allows access to internal components for maintenance. The design offers advantages for the location of a slit mask and filters. The instruments can also be used for imaging. Optical and opto-mechanical models and analyses are presented with specifications and expected performance.
This paper discusses the design and fabrication of ultra lightweight laser scanning mirrors from two types of metal-matrix composites for the next generation Space Vision System (SVS). The materials selected for this study were SiC particulate reinforced aluminum composite and beryllium-aluminum (AlBeMet) composite. Three mirror designs were made and compared in terms of mass, rotating inertia and first mode natural frequency. Mirror surface layer selection and processing were discussed. Problems encountered during the mirror fabrication and the ways to solve it were presented.
This paper presents the development of a laser range scanner (LARS) as a three-dimensional sensor for space applications. The scanner is a versatile system capable of doing surface imaging, target ranging and tracking. It is capable of short range (0.5 m to 20 m) and long range (20 m to 10 km) sensing using triangulation and time-of-flight (TOF) methods respectively. At short range (1 m), the resolution is sub-millimeter and drops gradually with distance (2 cm at 10 m). For long range, the TOF provides a constant resolution of plus or minus 3 cm, independent of range. The LARS could complement the existing Canadian Space Vision System (CSVS) for robotic manipulation. As an active vision system, the LARS is immune to sunlight and adverse lighting; this is a major advantage over the CSVS, as outlined in this paper. The LARS could also replace existing radar systems used for rendezvous and docking. There are clear advantages of an optical system over a microwave radar in terms of size, mass, power and precision. Equipped with two high-speed galvanometers, the laser can be steered to address any point in a 30 degree X 30 degree field of view. The scanning can be continuous (raster scan, Lissajous) or direct (random). This gives the scanner the ability to register high-resolution 3D images of range and intensity (up to 4000 X 4000 pixels) and to perform point target tracking as well as object recognition and geometrical tracking. The imaging capability of the scanner using an eye-safe laser is demonstrated. An efficient fiber laser delivers 60 mW of CW or 3 (mu) J pulses at 20 kHz for TOF operation. Implementation of search and track of multiple targets is also demonstrated. For a single target, refresh rates up to 137 Hz is possible. Considerations for space qualification of the scanner are discussed. Typical space operations, such as docking, object attitude tracking, and inspections are described.
This paper focuses on the characteristics and performance of a laser range scanner (LARS) with short and medium range 3D sensing capabilities for space applications. This versatile laser range scanner is a precision measurement tool intended to complement the current Canadian Space Vision System (CSVS). Together, these vision systems are intended to be used during the construction of the International Space Station (ISS). Integration of the LARS to the CSVS will allow 3D surveying of a robotic work-site, identification of known objects from registered range and intensity images, and object detection and tracking relative to the orbiter and ISS. The data supplied by the improved CSVS will be invaluable in Orbiter rendez-vous and in assisting the Orbiter/ISS Remote Manipulator System operators. The major advantages of the LARS over conventional video-based imaging are its ability to operate with sunlight shining directly into the scanner and its immunity to spurious reflections and shadows which occur frequently in space. Because the LARS is equipped with two high-speed galvanometers to steer the laser beam, any spatial location within the field of view of the camera can be addressed. This level of versatility enables the LARS to operate in two basic scan pattern modes: (1) variable scan resolution mode and (2) raster scan mode. In the variable resolution mode, the LARS can search and track targets and geometrical features on objects located within a field of view of 30 degrees X 30 degrees and with corresponding range from about 0.5 m to 2000 m. This flexibility allows implementations of practical search and track strategies based on the use of Lissajous patterns for multiple targets. The tracking mode can reach a refresh rate of up to 137 Hz. The raster mode is used primarily for the measurement of registered range and intensity information of large stationary objects. It allows among other things: target-based measurements, feature-based measurements, and, image-based measurements like differential inspection in 3D space and surface reflectance monitoring. The digitizing and modeling of human subjects, cargo payloads, and environments are also possible with the LARS. A number of examples illustrating the many capabilities of the LARS are presented in this paper.
This paper discuses the development of a short wavelength infrared laser ranging scanner system at the Canadian Space Agency in cooperation with the National Research Council Canada. A laser source at 1.54 micrometers wavelength is chosen for its relatively eye-safe property. The scanner system is to be considered for use as a space vision system for applications such as robot vision, satellite acquisition and tracking and high resolution 3D imaging for inspection. As an active system, this laser scanner offers an important advantage over conventional vision systems by providing its own illumination and having no dependence on ambient lighting. While providing relatively eye-safe operation, the choice of IR wavelength also improves the background rejection of solar radiation, the latter being about 5.8 times lower than in the visible. The system possesses two modes of operation for making range measurements: triangulation for short distances (0.5 m to 20 m) and time- of-flight for greater range (10 m to beyond 1 km). A short pulse high repetition rate laser is required for time-of- flight measurements. For space applications, the laser must be compact, rugged and efficient while operating in the eye- safe spectrum (1.5 to 1.8 micrometers ). Currently, a YAG laser with an OPO is used to demonstrate the system's operation at 1.54 micrometers , but is too bulky for a space environment. Eventually it will be replaced with a more compact and efficient fiber laser currently being developed. This paper presents the results of the capabilities and performance of the scanner.
An efficient method for tracking the attitude and translation of an object from a sequence of dense range images is demonstrated. The range data are sine coded and then Fourier transformed. By this process, planar surfaces in the image produce distinctive peaks in the Fourier transform spectrum. The position of a peak provides a direct measure of the normal of the plane. Tracking the positions of these peaks enables tracking the orientation of a known object. After computing and undoing the rotation, the translation is obtained by measuring the 3-D centroid of the segmented planar surfaces. All computations are closed form. The Fourier transform method is also used for segmentation. The integrative nature of the Fourier transform is very effective in attenuating the effect of noise and outliers. Results of tracking an object in a simulated range image sequence show high accuracy [0.2 deg in orientation and 0.2% root-mean-square (rms) error in translation with respect to the width of the object]. The system runs presently at 3 to 5 frames/s. The method promises real-time (video rate) performance with the addition of accelerator hardware for computing the Fourier transform. The approach is well suited for dynamic robotic vision applications.
An efficient method for tracking the attitude and translation of an object from a sequence of dense range images is demonstrated. The range data is sine encoded and then Fourier transformed. By this process, planar surfaces in the image produce distinctive peaks in the FT plane; the position of a peak provides a direct measure of the normal of the plane. By tracking the position of these peaks, the orientation of a known object can be tracked directly. The Fourier transform can also be used for segmentation. After computing and undoing the rotation, the translation is obtained by measuring the centroid of the segmented planar surfaces. The object must present at least three planar surfaces, for determining absolute orientation and translation. All computations are closed form. The integrative nature of the Fourier transform is very effective in attenuating the effect of noise and outliers. Results of tracking an object in a simulated range image sequence show high accuracy potential (0.2 deg. in orientation and 0.5% rms error in translation with respect to the dimension of the object). The method promises real-time (video rate) performance with the addition of accelerator hardware for computing the Fourier transform. The approach is well suited for dynamic robotic vision applications. Furthermore, the translation invariance of the Fourier transform essentially decouples the rotational and translational components of the motion, this contributes to the tracking performance.