Papers by Darren Erickson
Design of a Mechanically Actuated Reconfigurable Slit mask (MARS) for the NGST near IR spectrograph
Proceedings of SPIE, Mar 4, 2003
The Next Generation Space Telescope (NGST) will include a suite of three observational instrument... more The Next Generation Space Telescope (NGST) will include a suite of three observational instruments, including a Near Infrared multi-object Spectrograph (NIRSPEC). To achieve multi-object capability, the spectrograph must be equipped with a slit mask to position small apertures on a number of astronomical targets simultaneously. Unlike most ground based spectrographs, the NIRSPEC slit mask must be reconfigurable, so that it can be adapted and reused for each observation. Although a great deal of work has been put into the development of mirror and shutter arrays using MEMS technology, these devices are currently unproven and risky in space environments. Therefore, a Mechanically Actuated Reconfigurable Slit mask (MARS) is being developed by the NRC - Herzberg Institute of Astrophysics as an alternative in case MEMS devices do not achieve maturity in the required timeframe. The MARS device creates 50 slits in an opaque mask by translating individual metal shutters within an array of precise guide tracks. When two adjacent shutters are brought close together, a slit is formed between them. A unique, robust, and high-resolution actuation scheme has been developed to individually position the metal shutters with micron accuracy. It is based on a combination of custom electromagnetic and piezoelectric actuators working in a coordinated sequence of movements. This scheme incorporates the key goals of reliability, redundancy and low heat dissipation in the focal plane of the instrument. MARS has been modeled, and its principle components have been prototyped to test the feasibility of the concept. The model has undergone structural, thermal, electrical and magnetic analysis to ensure that it meets the restrictive requirements on mass, volume and launch survivability while maintaining very low power requirements and heat dissipation. The prototypes have shown that the MARS concept is a viable alternative for the NIRSPEC slit mask which is based on proven and stable technologies. Further development is underway to manufacture a prototype slit mask, and test its operation in a cryogenic (30 K) environment to simulate the actual conditions aboard NGST.
Proceedings of SPIE, Aug 18, 2005
Although many of the instruments planned for the TMT (Thirty Meter Telescope) have their own clos... more Although many of the instruments planned for the TMT (Thirty Meter Telescope) have their own closely-coupled adaptive optics systems, TMT will also have a facility Adaptive Optics (AO) system feeding three instruments on the Nasmyth platform. For this Narrow-Field Infrared Adaptive Optics System, NFIRAOS (pronounced nefarious), the TMT project considered two architectures. One, described in this paper, employs conventional deformable mirrors with large diameters of about 300 mm and this is the reference design adopted by the TMT project. An alternative design based on MEMS was also studied, and is being presented separately in this conference. The requirements for NFIRAOS include 0.8-5 microns wavelength range, 30 arcsecond diameter output field of view (FOV), excellent sky coverage, and diffraction-limited atmospheric turbulence compensation (specified at 133 nm RMS including residual telescope and science instrument errors.) The reference design for NFIRAOS includes multiple sodium laser guide stars over a 70 arcsecond FOV, and an infrared tip/tilt/focus/astigmatism natural guide star sensor within instruments. Larger telescopes require greater deformable mirror (DM) stroke. Although initially NFIRAOS will correct a 10 arcsecond science field, it uses two deformable mirrors in series, partly to provide sufficient stroke for atmospheric correction over the 30 m telescope aperture, but mainly to partially correct a 2 arcminute diameter "technical" field to sharpen near-IR natural guide stars and improve sky coverage. The planned upgrade to full performance includes replacing the groundconjugated DM with a higher actuator density, and using a deformable telescope secondary mirror as a "woofer." NFIRAOS incorporates an instrument rotator and selection of three live instruments: a near-Infrared integral field Imaging spectrograph, a near-infrared echelle spectrograph, and after upgrading NFIRAOS to full multi-conjugation, a wide field (30 arcsecond) infrared camera.
Proceedings of SPIE, Jul 12, 2008
The Gemini Planet Imager (GPi) is comprised of three main opto-mechanical systems: the Adaptive O... more The Gemini Planet Imager (GPi) is comprised of three main opto-mechanical systems: the Adaptive Optics (AO) system, the Calibration (CAL) system, and the Integral Field Spectrograph (IFS). Each of these subsystems are built and aligned independently, and then integrated into the final instrument. A truss framework called the Flexure Sensitive Structure (FSS) has been designed to locate each optical subsystem within the instrument, utilizing kinematic bipods to eliminate distortion due to flexure and thermal changes. Due to the distributed nature of the optical system, an end-to-end opto-mechanical modeling approach is taken using the NRC Integrated Model (NRCIM). This set of numerical tools was originally developed to support the Canadian VLOT and TMT telescope studies. The instrument structural response is calculated using a commercial finite element package; and the 6 degree-of-freedom rigid body motions of the optical elements are then passed to an optical model. Ray-tracing is performed to determine the line-of-sight errors at numerous critical focal planes and pupil planes. Disturbances to the system include gravity induced flexure and thermal distortions. Optical compensation using a combination of closedloop feedback and open-loop models are then applied using steering mirrors to improve the line-of-sight figures of merit. Finally, these figures of merit are compared against the system optical error budget to assess the overall performance of the opto-mechanical system.
Stability of Preamplifier in 84 - 116 GHz Receiver
2005 Joint 30th International Conference on Infrared and Millimeter Waves and 13th International Conference on Terahertz Electronics, 2005
Abstract The stability of InP HEMTs preamplifiers has been investigated in time and frequency dom... more Abstract The stability of InP HEMTs preamplifiers has been investigated in time and frequency domains at various cryogenic temperatures. It achieved a gain fluctuation of 5× 10-6/√ Hz and an Allan time of 9 seconds at 4 GHz bandwidth. The stability of a sideband ...
The Band 3 receiver (84-116 GHz) for ALMA
2005 Joint 30th International Conference on Infrared and Millimeter Waves and 13th International Conference on Terahertz Electronics
Design and characterization of sideband-separating SIS mixer RF hybrids for the Band 3 receiver (84-116 GHz)
... [6] S.-K. Pan, AR Kerr, MW Pospieszalski, EF Lauria, WK Crady, N. Horner, Jr., S. Srikanth, E... more ... [6] S.-K. Pan, AR Kerr, MW Pospieszalski, EF Lauria, WK Crady, N. Horner, Jr., S. Srikanth, E. Bryerton, K. Saini, SMX Claude, CC Chin, P. Dindo, G. Rodrigues, D. Derdall, JZ Zhang, and AW Lichtenberger, "A Fixed-Tuned SIS Mixer with Ultra-Wide-Band IF and Quantum ...
Gemini IRMOS: conceptual optical design of a multi-object adaptive optics-fed infrared integral-field spectrograph for the Gemini telescope
We discuss the optical design of an infrared multi-object integral-field spectrograph (IRMOS) tha... more We discuss the optical design of an infrared multi-object integral-field spectrograph (IRMOS) that is designed to take advantage of the multi-object adaptive optics corrected field at the Gemini telescope. The IRMOS is designed for the Gemini Telescope, so we call this instrument GIRMOS. The GIRMOS has four identical Integral-Field Spectrographs (IFSes), which employ a unique slicer design to arrange the integral field along a slit to obtain two-dimensional spectroscopy. Each IFS can pick off the individual fields of view of 1.0x1.0”, 2.1x2.1”, 4.2x4.2” over a 2’ diameter fieldof- regard, at the spatial sampling scales of 25mas, 50mas, and 100mas, respectively. Spectral resolutions of R~3000 and 8000 are available in J, H, and K-bands from 1.0 to 2.4μm. The primary design constraints are associated with diffractive effects from the grating and spectrograph camera.
arXiv (Cornell University), Jul 20, 2018
We present the results of an automated fibre optic test bench constructed at the University of Vi... more We present the results of an automated fibre optic test bench constructed at the University of Victoria as part of the Maunakea Spectroscopic Explorer (MSE) Fibre Transmission System (FiTS). In preparation for MSE-FiTS, we have begun characterizing the focal ratio degradation (FRD) of candidate multi-mode fibres with the ultimate goal of testing all ∼ 4000 MSE fibres. To achieve this, we have built an optical bench to perform an automated version of the collimated beam test. Herein we present the design of the bench and discuss the automation of components by introducing the Big FiTS Fibre Wrapper (Big FFW), our open-source automation software. We conclude with the results of tests performed using the Big FFW on a sample of candidate fibre, comparing the Big FFW results against those found using manual methods. Our results suggest that the candidate MSE fibre meets the science requirement of < 5% FRD at f /2 and find less than 1% disagreement between both measurement methods.
Proceedings of SPIE, Jun 14, 2006
In this paper, we provide an overview of the adaptive optics (AO) program for the Thirty Meter Te... more In this paper, we provide an overview of the adaptive optics (AO) program for the Thirty Meter Telescope (TMT) project, including an update on requirements; the philosophical approach to developing an overall AO system architecture; the recently completed conceptual designs for facility and instrument AO systems; anticipated first light capabilities and upgrade options; and the hardware, software, and controls interfaces with the remainder of the observatory. Supporting work in AO component development, lab and field tests, and simulation and analysis is also discussed. Further detail on all of these subjects may be found in additional papers in this conference.
Design and analysis of flexure mounts for precision optics
Proceedings of SPIE, Jul 14, 2008
The increasing demand within the astronomy community for direct detection of extrasolar Jovian pl... more The increasing demand within the astronomy community for direct detection of extrasolar Jovian planets is driving the development of the next generation of ground-based, precision instruments like the Gemini Planet Imager (GPI). The precision and stability of the opto-mechanical components within GPI needed to achieve the required 10-7 contrast will challenge the limits of design and material properties. This study
The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a powerful new instrument being built t... more The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a powerful new instrument being built to facilityclass standards for the Gemini telescope. It takes advantage of the latest developments in adaptive optics and integral field spectrographs. GIRMOS will carry out simultaneous high-angular-resolution, spatially-resolved
<title>Performance of the pre-production band 3 (84-116 GHz) receivers for ALMA</title>
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV, 2008
The Band 3 receiver, covering the 84-116 GHz frequency band is one of the 10 channels that will b... more The Band 3 receiver, covering the 84-116 GHz frequency band is one of the 10 channels that will be installed on the Atacama Large Millimeter Array (ALMA). A total of 73 units have to be built in two phases: 8 preproduction and then 65 production units. This paper reports on the assembly, testing and performance of the preproduction series of
Proc. 17th Int. Symp. on …, 2006
Band 3 covering 84 to 116 Cilz is one of the ten bands that will form the Front End Receiver for ... more Band 3 covering 84 to 116 Cilz is one of the ten bands that will form the Front End Receiver for the Atacama Large Millimetre Array. A Band 3 receiver prototype and one unit have been assembled and tested at the Herzberg Institute of Astrophysics. This paper will give an overview of the Band 3 design and also present the performance of the first deliverable unit. The single sideband (SSB) system noise exceeds the specifications (TSSB< 37 K) over the full RF band with a minimum TSSB of 26 K and a maximum of 34 K In addition to details of the system noise performance other characteristics such as image rejection and cross-polarization are also presented.
Gemini IRMOS: preliminary optical design of a multi-object adaptive optics-fed infrared integral-field spectrograph
Ground-based and Airborne Instrumentation for Astronomy VIII, 2020
We discuss the preliminary end-to-end optical design of an infrared multi-object integral-field s... more We discuss the preliminary end-to-end optical design of an infrared multi-object integral-field spectrograph (GIRMOS) that is designed to take advantage of the multi-object adaptive optics corrected field at the Gemini telescope. GIRMOS’s optical design consists of object selection pick-offs, an adaptive optics (AO) system, and four identical Integral-Field Spectrographs (IFSes), which employ an image slicer to arrange the integral field along a slit. Each IFS can pick off the individual FOV of 1.0x1.0”, 2.0x2.0”, 4.0x4.0” over a 2’ diameter field-of-regard, at a spatial sampling of 25mas, 50mas, and 100mas, respectively. The pick-offs can also be configured in close-packed arrangement to image a single field. Spectral resolutions of R~3000 and 8000 are available in Y, J, H, and K-bands from 0.95 to 2.4μm.
Gemini Infrared Multi-Object Spectrograph: preliminary design overview
Ground-based and Airborne Instrumentation for Astronomy VIII, 2020
The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is an adaptive optics-fed multi-object int... more The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is an adaptive optics-fed multi-object integral field spectrograph with a parallel imaging capability. GIRMOS implements multi-object adaptive optics (MOAO) for each of its spectrographs by taking advantage of the infrastructure offered by Gemini upcoming wide-field AO facility at Manua Kea. The instrument offers the ability to observe four objects simultaneously within the Gemini-North AO (GNAO) system’s field-of-regard or a single object by tiling the four fields that feed light to four separate spectrographs. Each integral field spectrograph has an independent set of selectable spatial scales (0.025", 0.05", and 0.1" /spaxel) and spectral resolution (R 3,000 and 8,000) within an operating band of 0.95 2.4µm. These spatial scales correspond to indvidual spectrograph fields of view of 1x1", 2X2" , and 4x4", respectively. GIRMOS’s imager offers Nyquist sampling of the diffraction limit in H-band over a 85x85" imaging field. The imager can function in a parallel data acquisition mode with just minor vignetting spectroscopic pick- offs when they are deployed.
Preliminary mechanical design of the Gemini Infrared Multi-Object Spectrograph (GIRMOS) Cryostat
Ground-based and Airborne Instrumentation for Astronomy VIII, 2020
In this paper we discuss the mechanical design of the GIRMOS Cryostat. GIRMOS is an adaptive opti... more In this paper we discuss the mechanical design of the GIRMOS Cryostat. GIRMOS is an adaptive optics fed multi-object Integral-Field Spectrograph with a parallel imaging capability and will be installed at the Gemini North Observatory. This instrument includes four separate identical spectrograph channels arranged symmetrically around the central axis of the instrument which provide it its multiplexing capability. Each spectrograph channel starts off at the object selection mechanism. The object selection mechanism contains four motorized fold mirror assemblies which scan the incoming light from the telescope to look at four separate objects simultaneously or combine their efforts to look at a single object in a tiled mode. Each of the four individual beams from the object selection system are then directed into the instrument dewar via separate entrance windows. Within the dewar each IFS beam moves through an anamorphic relay, an optical image slicer assembly and eventually makes it to a Spectrograph unit. All of these assemblies are located on a single cold bench within the dewar. The instrument imager is located along the central axis of the dewar and is housed in the cold bench as well. In this paper we will provide some details regarding the Cryostat design, the mechanical packaging of the IFS and imager along with some of the thermal load mitigation techniques employed. We will also discuss some key performance requirements that were expected from the Cryostat and the design choices we made in order to achieve them.
Gemini infrared multi-object spectrograph: calibration system
Ground-based and Airborne Instrumentation for Astronomy VIII, 2020
The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a four-channel adaptive-optics-assisted... more The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a four-channel adaptive-optics-assisted integralfield spectrograph being designed for the Gemini 8-meter telescopes. Deployed behind the Gemini-North Adaptive Optics (GNAO) system, it will provide spatially-resolved spectra over the 0.9-2.4 um wavelength range for four fields simultaneously. Its multi-object adaptive optics will provide additional correction of the target fields, beyond that achieved by the GNAO system, enabling integral-field spectroscopy with near-diffraction-limited resolution and unprecedented sensitivity. A parallel imaging channel will view the field of regard and provide a simultaneous imaging capability. The primary science objectives include mapping chemical abundances, star formation and kinematics in high-redshift galaxies, and studies of stellar populations, star formation and supermassive black holes in nearby galaxies. In order to support the science programs, GIRMOS requires a system that enables photometric, spectroscopic and astrometric calibration. The GIRMOS Calibration System (CAL) serves this purpose, uniformly illuminating the spectroscopic and imaging channels with both continuous and narrow-line light for flat-field and wavelength calibration. In order to replicate the light path through the instrument as closely as possible, the CAL optical system matches both the pupil position and the focal ratio of the beam delivered to the instrument by GNAO. CAL also includes a metrology system, employing focal-plane masks, to permit precise calibration of the positions of the pick-off arms of the object selection system, and to map optical distortion and instrument flexure. This paper summarizes the key requirements of the CAL system, presents its conceptual design and discusses its expected performance.
TIKI: a 10-micron Earth-like planet finder for the Gemini South telescope
The TIKI instrument is a next generation 10-micron cryogenic extreme adaptive optics (ExAO) image... more The TIKI instrument is a next generation 10-micron cryogenic extreme adaptive optics (ExAO) imager being designed for the Gemini South telescope. Its goal is to detect the thermal emission of Earth-like planets in orbit around Alpha Centauri A or B. TIKI is also a prototype for future TMT instruments capable of imaging Earth- like planets around a larger star sample, and performing low spectral resolution characterization to search for biomarkers on detected planets. The science module will operate at cryogenic temperature in order to minimize thermal background, dominant in the 10-micron wavelength range. The instrument will use Adaptive Optics, a vortex coronagraph, focal plane wavefront sensing, and advanced post-processing techniques to reach a 1E-7 contrast in less than 200 hours of observing time. It aims to be background-limited in the 2-5λ/D zone, which corresponds to the habitable zone around the two Sun-like stars of the Alpha Centauri system. In this paper, we give an ove...
Concept of operations versus operations concept: how do you choose?
Systems engineering as a discipline is relatively new in the ground-based astronomy community and... more Systems engineering as a discipline is relatively new in the ground-based astronomy community and is becoming more common as projects become larger, more complex and more geographically diverse. Space and defense industry projects have been using systems engineering for much longer, however those projects don’t necessarily map well onto groundbased astronomy projects, for various reasons. Fortunately, many of the processes and tools have been documented by INCOSE, NASA, SEBoK and other organizations, however there can be incomplete or conflicting definitions within the process and implementation is not always clear. For ground-based systems engineers, adopting these existing processes can be confusing. One area of particular uncertainty involves how, when and where to document operations concepts in a way that captures astronomers’ needs, translates them into concise and complete requirements without over-constraining the design teams or over-burdening the project with complex requi...
Design of a mechanically actuated reconfigurable slitmask for the NGST near IR spectrograph
The National Research Council of Canada, Herzberg Institute of Astrophysics has been developing a... more The National Research Council of Canada, Herzberg Institute of Astrophysics has been developing a reconfigurable slitmask intended for the NGST near IR spectrograph. The Mechanically Actuated Reconfigurable Slitmask (MARS) creates 50 slits in the telescope focal plane. The slit location and width are adjustable, but the height is fixed. Reconfiguration of the mask components is achieved using a combination of electromagnetic and piezoelectric actuators. This actuation scheme has undergone structural, electrical, thermal and magnetic analysis. Several prototype components have also been built and tested. This analysis and testing indicates that the MARS device represents a viable concept for creating slits within the NGST near IR spectrograph.
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Papers by Darren Erickson