The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. This
paper describes the methods used for optical alignment of the adaptive optics (AO) bench. The optical alignment of the
off-axis paraboloid mirrors was done using a pre-alignment method utilizing a HeNe laser and alignment telescopes
followed by a fine-tuning using a Shack-Hartmann wavefront sensor and a shear plate. A FARO arm measuring system
was used to place the fiducials for the alignment. Using these methods the AO bench was aligned to 13nm RMS of
The success of the high resolution nightglow studies conducted with the Keck telescopes on Mauna Kea and the Very
Large Telescopes in Chile led to the design of the Compact Echelle Spectrograph for Aeronomical Research (CESAR).
This is an echelle spectrograph with grating post-dispersion that will be dedicated to nightglow studies at high spectral
resolution (R ~ 20000) between 300-1000 nm, and that will be easily deployable at different sites. The development of
CESAR is conducted by SRI International, and INO is involved in the optical design and integration of the spectrograph
camera, whose all-spherical form is based on the camera of the HIRES spectrograph at the Keck I telescope. The
detailed optical design is used to calculate the position of the spectral elements on the detector, predict their image
quality, and estimate the level of stray light. This paper presents the methodology used in these analyses.
Coupling of optical signal into a single mode waveguide has been a difficult problem for a long time. An advanced fibre coupling device (AFCD) is a high performance fibre coupling system that provide wavefront correction, vibration isolation and alignment. We will discuss two AFCD, one for a ground to space communication link an a second for astronomical interferometric application (DARWIN and VLTI interferometer).
INO in collaboration with DRDC Valcartier has been involved in the design and development of uncooled IR bolometric detector technology since the early 1990s for a broad range of military and commercial applications. From the beginning, the strategy has been to develop small-size bidimensional detector arrays and specialty linear arrays, both equipped with on-chip readout electronics. The detector arrays have been implemented in various instruments for both imaging and non-imaging applications. This paper describes two TWS1 and TWS2 prototypes of single band thermal weapon sights (TWS) making use of a novel catadioptric, i.e. refractive/reflective, optics and INO's miniature IR cameras. These cameras employ a 160x120 pixel uncooled bolometric FPA with a 52 µm pitch and NETD at 50 mK, and modular electronics consisting of three boards stacked together to fit into a 3-inch cube volume. The ultra lightweight catadioptric objective is inherently athermalized in the -30°C to +40°C range. The TWS1 is also equipped with a miniature RF link allowing bi-directional video transmission. This TWS1 weighs only 900 g and has a total volume of about 75 in3. Its power consumption is 2 W. The experimental performance showed that human detection, recognition and identification could be achieved at 800 m, 200 m, and 120 m, respectively. Construction of an improved TWS2 model is in progress. The objective is the reduction of TWS2 model weight down to 700 g, its volume down to 50 in3, replacing the RF video link with a wireless digital link, and increasing resolution to 320x240 pixels.
We present three designs and tolerances of wide-field imagers (30'30 arc-minutes or larger) for astronomical surveying. Two infrared cameras (CPAPIR and PANORAMIX II) were designed for the 0.8-2.4 μm band and a third one (WIRCAM) for the visible and near-infrared band extending from 410 nm to 950 nm. The cameras are installed on the telescopes of the Canada-France-Hawaii (Hawaii, USA) and Mont Megantic Observatories (Quebec, Canada). The three cameras are compact, use only spherical refractive components and have an internal pupil accessible for insertion of filtering components. A Lyot stop must be used in the infrared camera for background rejection. For PANORAMIX II, a set of filters is used at the internal pupil. Correction of the large off-axis aberrations generated by the telescopes, wide spectral coverage, material choices, cryogenic temperature and alignment were the main design challenges. Also, tolerancing was particularly critical for the infrared cameras because they are cryogenically cooled, thus forbidding adjustment of internal components. The cameras’ theoretical performances are presented in terms of point-spread function, encircled energy and distortion.
The optical design of the wide-field infrared camera CPAPIR (Camera PAnoramique Proche InfraRouge) for the Mont Megantic Observatory (OMM) has been completed. CPAPIR will be a unique wide-field camera at the OMM. It has a full field of view of 0.71 degrees, an instantaneous field of view of 0.88 arc-seconds, and a spectral coverage of 0.85 - 2.5 μm. The camera is operated under vacuum and at cryogenic temperature. The performance (image quality, vignetting, cold stop efficiency, ghost analysis and tolerancing) of CPAPIR has been optimized at cold temperature using cryogenic indices of refraction and coefficients of thermal.
As part of the Infrared Eye project, this article describes the design of large-deviation, achromatic Risley prisms scanning systems operating in the 0.5 - 0.92 and 8 - 9.5 μm spectral regions. Designing these systems is challenging due to the large deviation required (zero - 25 degrees), the large spectral bandwidth and the mechanical constraints imposed by the need to rotate the prisms to any position in 1/30 second. A design approach making extensive use of the versatility of optical design softwares is described. Designs consisting of different pairs of optical materials are shown in order to illustrate the trade-off between chromatic aberration, mass and vignetting. Control of chromatic aberration and reasonable prism shape is obtained over 8 - 9.5 μm with zinc sulfide and germanium. The design is more difficult for the 0.5 - 0.92 μm band. Trade-offs consist in using sapphire with Cleartran® over a reduced bandwidth (0.75 - 0.9 μm ) or acrylic singlets with the Infrared Eye in active mode (0.85 - 0.86 μm). Non-sequential ray-tracing is used to study the effects of fresnelizing one element of the achromat to reduce its mass, and to evaluate detector narcissus in the 8 - 9.5 μm region.