Integration and first results of the CAMCAO NIR camera (original) (raw)
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Integration and first results of the CAMCAO NIR camera
2006
This paper presents the integration and first results for the CAMCAO NIR camera. The camera was built for the ESO Multi-conjugate Adaptive optics Demonstrator, where it is presently operating, to evaluate the feasibility of this Adaptive Optics technique. On a second phase it will work directly at the Nasmyth focus of the VLT. CAMCAO is a high resolution, wide field of view NIR camera, that is using the 2k×2k HgCdTe HAWAII- 2 infrared detector from Rockwell Scientific, controlled by the ESO IRACE system. The camera operates in the near infrared region between 1.0 μm and 2.5 μm wavelength using an eight position filter wheel with J, H, K', K-continuum and Brγ filters. Both the integration experience and the results obtained in the mechanical, vacuum, cryogenics and optical tests are presented, including all relevant parameters in the ESO specifications. The requirement of mechanical stiffness together with light weight was achieved yielding a total weight of less than 90 Kg. The camera fulfills both cryogenic and vacuum stability requirements. The temperature within the detector is maintained at 80K by an accurate control loop, ensuring mK stability, after cooling down the detector at a rate kept below 0.5 K/min. The optical performance tests were made using a Fizeau interferometer both for the individual optical components and complete setup. The infrared optical validation measurements were performed by re-imaging a point source in the camera focal plane and measuring the PSF with the detector. The computed Strehl ratio reached 95% in the central region of the FoV, with values larger than 90% in a area covering 88% of the focal plane.
Storage and Retrieval for Image and Video Databases, 2004
The CAMCAO instrument is a high resolution near infrared (NIR) camera conceived to operate together with the new ESO Multi-conjugate Adaptive optics Demonstrator (MAD) with the goal of evaluating the feasibility of Multi-Conjugate Adaptive Optics techniques (MCAO) on the sky. It is a high-resolution wide field of view (FoV) camera that is optimized to use the extended correction of the atmospheric turbulence provided by MCAO. While the first purpose of this camera is the sky observation, in the MAD setup, to validate the MCAO technology, in a second phase, the CAMCAO camera is planned to attach directly to the VLT for scientific astrophysical studies. The camera is based on the 2k×2k HAWAII2 infrared detector controlled by an ESO external IRACE system and includes standard IR band filters mounted on a positional filter wheel. The CAMCAO design requires that the optical components and the IR detector should be kept at low temperatures in order to avoid emitting radiation and lower detector noise in the region analysis. The cryogenic system includes a lN 2 tank and a specially developed pulse tube cryo-cooler. Field and pupil cold stops are implemented to reduce the infrared background and the stray-light. The CAMCAO optics provide diffraction limited performance down to J Band, but the detector sampling fulfills the Nyquist criterion for the K band (2.2 mm).
Evaluation of highly corrected optics by measurement of the Strehl ratio
Applied Optics, 1992
The Strehl ratio (SR) is a measure of image quality that is especially relevant to recording media of finite contrast, such as photoresist, film, and the human retina. The SR is accessible experimentally from the total power and maximum irradiance in the point spread function (PSF). Measurement error is introduced by the finite dimension of the pinhole aperture that is used to generate a detectable image. This systematic error can be related parametrically to the object geometry and illumination system, and the SR can be corrected to within a few percent. Systematic corrections also compensate for the portion of the PSF irradiance that falls outside the data integration window in the image plane. An optical test bench is constructed to measure the SR over the lens field and azimuth to an accuracy of 5% and a repeatability of 1%.
Preliminary optical design of PANIC, a wide-field infrared camera for CAHA
Ground-based and Airborne Instrumentation for Astronomy II, 2008
In this paper, we present the preliminary optical design of PANIC ‡ (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Calar Alto 2.2 m telescope. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 µm pixel. A mosaic of four Hawaii 2RG of 2k x 2k made by Teledyne is used as detector and will give a field of view of 31.9 arcmin x 31.9 arcmin. This cryogenic instrument has been optimized for the Y, J, H and K bands. Special care has been taken in the selection of the standard IR materials used for the optics in order to maximize the instrument throughput and to include the z band. The main challenges of this design are: to produce a well defined internal pupil which allows reducing the thermal background by a cryogenic pupil stop; the correction of off-axis aberrations due to the large field available; the correction of chromatic aberration because of the wide spectral coverage; and the capability of introduction of narrow band filters (~1%) in the system minimizing the degradation in the filter passband without a collimated stage in the camera. We show the optomechanical error budget and compensation strategy that allows our as built design to met the performances from an optical point of view. Finally, we demonstrate the flexibility of the design showing the performances of PANIC at the CAHA 3.5m telescope.
TIFR Near Infrared Imaging Camera-II on the 3.6 m Devasthal Optical Telescope
Journal of Astronomical Instrumentation, 2018
Tata Institute of Fundamental Research (TIFR) Near Infrared Imaging Camera-II (TIRCAM2) is a closed-cycle Helium cryo-cooled imaging camera equipped with a Raytheon 512[Formula: see text][Formula: see text][Formula: see text]512 pixels InSb Aladdin III Quadrant focal plane array (FPA) having sensitivity to photons in the 1–5[Formula: see text][Formula: see text] wavelength band. In this paper, we present the performance of the camera on the newly installed 3.6[Formula: see text]m Devasthal Optical Telescope (DOT) based on the calibration observations carried out during 2017 May 11–14 and 2017 October 7–31. After the preliminary characterization, the camera has been released to the Indian and Belgian astronomical community for science observations since 2017 May. The camera offers a field-of-view (FoV) of [Formula: see text] on the DOT with a pixel scale of 0.169[Formula: see text]. The seeing at the telescope site in the near-infrared (NIR) bands is typically sub-arcsecond with the ...
Final Optical Design of PANIC, a Wide-Field Infrared Camera for CAHA
Astrophysics and Space Science Proceedings, 2010
We present the Final Optical Design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Ritchey-Chrtien focus of the Calar Alto 2.2 m telescope. This will be the first instrument built under the German-Spanish consortium that manages the Calar Alto observatory. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 µm pixel. The optical design produces a well defined internal pupil available to reducing the thermal background by a cryogenic pupil stop. A mosaic of four detectors Hawaii 2RG of 2kx2k, made by Teledyne, will give a field of view of 31.9 arcmin x 31.9 arcmin.
Characterization, Testing and Operation of Omega2000 Wide Field Infrared Camera
2014
Omega2000 is the ¯rst near infrared (NIR) wide ¯eld camera installed on the 3.5 m telescope at Calar Alto which operates with a 2kx2k HAWAII-2 FPA. Each component of the camera system must suit high requirements to exploit the facilities provided by the imaging sensor. To meet these requirements was a great challenge in design and realization of the optics, the mechanical part and the electronics. The cryogenic optical system with a warm mirror bae can produce excellent optical quality and high sensitivity over the whole 15.4x15.4 arcmin ¯eld of view. The readout electronics together with the camera control software provide multi functional data acquisition and the camera control software can perform the readout and on-line data reduction simultaneously at a high data rate. Di®erent operational and readout modes of the data acquisition of the detector both for engineering and scienti¯c purpose were implemented, tested and optimized and the characteristics of three HAWAII-2 detectors...
Wavefront sensing within the VISTA infrared camera
2004
VISTA is a 4-metre survey telescope currently being constructed on the NTT peak of ESO"s Cerro Paranal Observatory. The telescope will be equipped with a dedicated infrared camera providing images of a 1.65 degree field of view. The telescope and camera are of an innovative f/3.26 design with no intermediate focus and no cold stop. The mosaic of 16 IR detectors is located directly at Cassegrain focus and a novel baffle arrangement is used to suppress stray light within the cryostat. The pointing and alignment of the telescope and camera is monitored by wavefront sensing elements within the camera cryostat itself. This paper describes the optical, mechanical, electronic and thermal design of the combined curvature sensor and auto-guider units positioned at the periphery of the camera field of view. Centroid and image aberration data is provided to the telescope control system allowing real time correction of pointing and alignment of the actively positioned M2 unit. Also described are the custom optics, mounted in the camera filter wheel, which are used to perform near on-axis high order curvature sensing. Analysis of the corresponding defocused images allows calibration tables of M1 actuator positions to be constructed for varying telescope declination and temperature.
Monthly Notices of the Royal Astronomical Society
We show numerical simulations with monochromatic light in the visible for the LBTI Fizeau imager, including opto-dynamical aberrations due here to adaptive optics (AO) errors and to differential piston fluctuations, while other errors have been neglected. The achievable Strehl by the LBTI using two AO is close to the Strehl provided by a single standalone AO system, as long as other differential wavefront errors are mitigated. The LBTI Fizeau imager is primarily limited by the AO performance and by the differential piston/tip-tilt errors. Snapshots retain high-angular resolution and high-contrast imaging information by freezing the fringes against piston errors. Several merit functions have been critically evaluated in order to characterize point spread functions and the modulation transfer functions for highcontrast imaging applications. The LBTI Fizeau mode can provide an image quality suitable for standard science cases (i.e. a Strehl above 70 per cent) by performing both at a time: an AO correction better than ≈λ/18 RMS for both short and long exposures, and a piston correction better than ≈λ/8 RMS for long exposures or simply below the coherence length for short exposures. Such results, which can be applied to any observing wavelength, suggest that AO and piston control at the LBTI would already improve the contrast at near-and mid-infrared wavelengths. Therefore, the LBTI Fizeau imager can be used for high-contrast imaging, providing a high-Strehl regime (by both AO systems), a cophasing mode (by a fringe tracker) and a burst mode (by a fast camera) to record fringed speckles in short exposures.
The near infrared camera for the Subaru Prime Focus Spectrograph
Ground-based and Airborne Instrumentation for Astronomy V, 2014
We present the detailed design of the near infrared camera for the SuMIRe (Subaru Measurement of Images and Redshifts) Prime Focus Spectrograph (PFS) being developed for the Subaru Telescope. The PFS spectrograph is designed to collect spectra from 2394 objects simultaneously, covering wavelengths that extend from 380 nm -1.26 µm. The spectrograph is comprised of four identical spectrograph modules, with each module collecting roughly 600 spectra from a robotic fiber positioner at the telescope prime focus. Each spectrograph module will have two visible channels covering wavelength ranges 380 nm -640 nm and 640 nm -955 nm, and one near infrared (NIR) channel with a wavelength range 955 nm -1.26 µm. Dispersed light in each channel is imaged by a 300 mm focal length, f/1.07, vacuum Schmidt camera onto a 4k x 4k, 15 µm pixel, detector format. For the NIR channel a HgCdTe substrate-removed Teledyne 1.7 µm cutoff device is used. In the visible channels, CCDs from Hamamatsu are used. These cameras are large, having a clear aperture of 300 mm at the entrance window, and a mass of ∼ 250 kg.