Neil Rowlands

Extreme Adaptive Optics for the Thirty Meter Telescope

Direct detection of extrasolar Jovian planets is a major scientific motivation for the construction of future extremely large telescopes such as the Thirty Meter Telescope (TMT). Such detection will require dedicated high-contrast AO systems. Since the properties of Jovian planets and their parent stars vary enormously between different populations, the instrument must be designed to meet specific scientific needs rather than a simple metric such as maximum Strehl ratio. We present a design for such an instrument, the Planet Formation Imager (PFI) for TMT. It has four key science missions. The first is the study of newly-formed planets on 5-10 AU scales in regions such as Taurus and Ophiucus - this requires very small inner working distances that are only possible with a 30m or larger telescope. The second is a robust census of extrasolar giant planets orbiting mature nearby stars. The third is detailed spectral characterization of the brightest extrasolar planets. The final targets are circumstellar dust disks, including Zodiacal light analogs in the inner parts of other solar systems. To achieve these, PFI combines advanced wavefront sensors, high-order MEMS deformable mirrors, a coronagraph optimized for a finely- segmented primary mirror, and an integral field spectrograph.

THE MONTREAL NEAR-INFRARED CAMERA

A near-infrard (10 microns-2.5 microns) camera in use at the Canada-France-Hawaii Telescope and at the Observatoire du Mont Megantic 1.6 m telescope is described. The camera is based on a NICMOS3 256X256 HgCdTe array detector. While it is used for broad-band imaging and polarimetry through the standard J, H, and K filters, a distinguishing feature of its design is the use of circular variable filters for spectral line imaging in regions of strong continuum emission. The control system was designed to minimize overhead and be simple to use and to maintain. The performance of the instrument is described and illustrated with images of the H2 emission from the Cepheus A star formation region and a K-band image of the environment of the quasar 3C 345.

Waves Michelson Interferometer: a visible/near-IR interferometer for observing middle atmosphere dynamics and constituents

The Waves Michelson Interferometer (WAMI) is designed to provide simultaneous measurements of dynamical and constituent signatures in the upper stratosphere, mesosphere and lower thermosphere. It is being included as part of the Waves Explorer mission (G. Swenson, P.I. being proposed for NASAs MIDEX program. It is a field-widened Michelson interferometer based on the same design principle as the successful Wind Imaging Interferometer (WINDII). WAMI includes visible and near-IR channels, a segmented interferometer mirror for simultaneous fringe sampling at different optical paths and views the atmosphere in six distinct directions. Use of the segmented mirrors minimizes the aliasing of atmospheric intensity variations into the fringe parameter determinations. This technique also allows two emissions to be viewed simultaneously through the same optical channel. The emissions chosen include lines in the molecular oxygen IR-atmospheric band, a doublet in the hydroxyl Meinel bands and the oxygen green line. The daytime coverage includes winds from 45 to 180 km, and rotational temperature and ozone density from 45 to 95 km. The nighttime coverage is restricted to the airglow layer centered near 90 km where atomic oxygen, horizontal wind and rotational temperature measurements are provided. These measurements provide a rich data set from which dynamics, energetics and constituent budgets can be determined.

The JWST fine guidance sensor

The science instrumentation for the James Webb Space Telescope (JWST) has concluded its Phase A definition stage. We have developed a concept for the JWST Fine Guidance Sensor (FGS), which will form the Canadian contribution to the mission. As part of the JWST re-plan in early 2003, the FGS design was recast to incorporate a narrow-band (R~100) science-imaging mode. This capability was previously resident in the NIRCam instrument. This FGS science mode makes use of tunable filters and filter wheels containing blocking filters, calibration sources and aperture masks. The science function of the FGS Tunable Filters (FGS-TF) remains complementary to the NIRCam science goals. Narrow-band FGS-TF imaging will be employed during many of the JWST deep imaging surveys to take advantage of the sensitivity to emission line objects. The FGS-TF will also provide a coronagraphic capability for the characterization of host galaxies of active galactic nuclei and for the characterization of extra solar planets. The primary function of the FGS remains to provide the sensor data for the JWST Observatory line-of-sight stabilization system. We report here on the overall configuration of the FGS and we indicate how the concept meets the performance and interface requirements.

The James Webb Space Telescope science instrument suite: an overview of optical designs

The James Webb Space Telescope (JWST) Observatory, the follow-on mission to the Hubble Space Telescope and to the Spitzer Space Facility, will yield astounding breakthroughs in the realms of infrared space science. The science instrument suite for this Observatory will consist of a Near-Infrared Camera, a Near-Infrared Spectrograph, a Mid-Infrared Instrument with imager, coronagraph and integral field spectroscopy modes, and a Fine Guider System Instrument with both a Guider module and a Tunable Filter Module. In this paper we present an overview of the optical designs of the telescope and instruments.

Miniature spectrometers for planetary remote sensing

Tight resource allocations are a driving concern for interplanetary remote sensing instruments. Through ongoing development work on Earth-orbiting sensor instruments EMS Space Science has developed the expertise to build extremely efficient and compact spectrometers for multiple planetary applications. We compare the Superiority of high resolution spectrometer technologies and discuss the improvements associated with field-widening. We present new concepts for high-performance miniature planetary spectrometers: rugged monolithic wide-field imaging tunable filters, Michelsons, and spatial heterodyne spectrometers for atmospheric and ground-based applications. Performance and resource estimates are provided for each system concept.

An imaging interferometer for satellite observations of wind and temperature on Mars, the Dynamic Atmosphere Mars Observer (DYNAMO)

To date there have not been any direct measurements of winds in the Martian atmosphere. Measurements such as these are needed in order to understand the nature of the circulation and the transport of constituents in the atmosphere of this planet. In this paper, a conceptual design for a small visible/near-IR imaging interferometer capable of fulfilling this need is described. The design is based on a similar successful instrument, the Wind Imaging Interferometer (WINDII), which flew in Earth orbit. The basic measurement set includes Doppler shifts (from which wind is derived), rotational temperatures, line widths and radiances of isolated lines in the O2(α1Δg) band airglow and O(1S) airglow emission. The design challenges which were met in converting an instrument designed for terrestrial applications to one capable of flying to Mars and operating in conditions there include reducing the mass and power requirements and adapting the instrument to appropriate data rate and S/N requirements. The resulting instrument has a mass of approximately 15 kg, requires on average, 10 Watts of power and has a data rate of 32Mbits/day. In this paper the design of this instrument and how it accommodates the particular requirements of a Mars mission are described.

Tunable filters for JWST Fine Guidance Sensor

The Canadian contribution to the James Webb Space Telescope (JWST) mission will be the Fine Guidance Sensor (FGS), incorporating a science-observing mode using tunable filters. We describe here the requirements, the opto-mechanical design concept and bread-board test results for the JWST FGS tunable filters. The FGS requires two continuously tunable filters over the wavelength ranges 1.2 - 2.4 microns and 2.4 - 4.8 microns each having a spectral resolution in the range of R~70 to 200. The selected implementation uses dielectric coated Fabry-Perot etalon plates with a small air gaps. The design finesse is ~30 and the filters are used in 3rd order. The operating temperature is ~35K. Current coating designs provide implementations that require only five blocking filters in each wavelength range to suppress unwanted orders. The filters will be scanned via the use of low voltage piezo-electric transducers. We present results from cryogenic tests of coating samples, PZT actuators and a structural model. The PZT actuators were found have a displacement of ~3.3 microns at 30K with an applied voltage of 125V, more than sufficient for the required scan of the Fabry-Perot plate spacing. The prototype etalon coating was found to be very stable cryogenically, having a measured change of transmission of only ~1% at 77K. The same coating on a 12.7 mm thick substrate, similar to that planned for the filter, was found to have a 18 nm peak-to-valley surface figure change when cooled to 30K. These results demonstrate that the development of tunable filters for the JWST FGS is on track to meet the technology readiness requirements of the program.

Detector characterization for the JWST fine guidance sensor

The James Webb Space Telescope Fine Guidance Sensor makes use of three 2048×2048 five micron cutoff HAWAII- 2RG HgCdTe detectors from Teledyne Imaging Systems. The FGS consists of two Guider channels and one Tunable Filter Imager (TFI) channel. We report here on our efforts to optimize the performance of the FGS detector sub-system consisting of the detector arrays, the Teledyne SIDECAR ASIC, and the FGS specific SIDECAR Control Electronics. The FGS-Guider has a number of unique readout modes which are required to support observatory operations, requiring different optimizations for these readout modes compared to those required for science observations with the TFI.

Optical-mechanical operation of the F2T2 filter: a tunable filter designed to search for First Light

The Flamingos-2 Tandem Tunable filter is a tunable, narrow-band filter, consisting of two Fabry-Perot etalons in series, capable of scanning to any wavelength from 0.95 to 1.35 microns with a spectral resolution of R~800. It is an accessory mode instrument for the near-IR Flamingos-2 imaging-spectrograph designed for the Gemini South 8m Observatory and will be fed through the upcoming Multi-Conjugate Adaptive Optics feed. The primary science goal of the F2T2 filter is to perform a ground-based search for the first star forming regions in the universe at redshifts of 7 < z < 11. The construction of the F2T2 filter is complete and it is currently in its calibration and commissioning phases. In this proceeding, we describe the calibration and performance of the instrument.