MICADO will enable the ELT to perform diffraction limited near-infrared observations at first light. The instrument’s capabilities focus on imaging (including astrometric and high contrast) as well as single object spectroscopy. This contribution looks at how requirements from the observing modes have driven the instrument design and functionality. Using examples from specific science cases, and making use of the data simulation tool, an outline is presented of what we can expect the instrument to achieve.
MICADO will equip the E-ELT with a first light capability for diffraction limited imaging at near-infrared wavelengths. The instrument’s observing modes focus on various flavours of imaging, including astrometric, high contrast, and time resolved. There is also a single object spectroscopic mode optimised for wavelength coverage at moderately high resolution. This contribution provides an overview of the key functionality of the instrument, outlining the scientific rationale for its observing modes. The interface between MICADO and the adaptive optics system MAORY that feeds it is summarised. The design of the instrument is discussed, focusing on the optics and mechanisms inside the cryostat, together with a brief overview of the other key sub-systems.
MICADO will be the first-light wide-field imager for the European Extremely Large Telescope (E-ELT) and will provide diffraction limited imaging (7mas at 1.2mm) over a ~53 arc-second field of view. In order to support various consortium activities we have developed a first version of SimCADO: an instrument simulator for MICADO. SimCADO uses the results of the detailed simulation efforts conducted for each of the separate consortium-internal work packages in order to generate a model of the optical path from source to detector readout. SimCADO is thus a tool to provide scientific context to both the science and instrument development teams who are ultimately responsible for the final design and future capabilities of the MICADO instrument. Here we present an overview of the inner workings of SimCADO and outline our plan for its further development.
We evaluate the performance of the Multi-conjugate Adaptive optics Demonstrator (MAD) from H and Ks imaging of
30 Doradus in the Large Magellanic Cloud. Maps of the full-width half maximum (FWHM) of point sources in the H and Ks images are presented, together with maps of the Strehl ratio achieved in the Ks-band observations. Each of the
three natural guide stars was at the edge of the MAD field-of-view, and the observations were obtained at relatively large
airmass (1.4-1.6). Even so, the Strehl ratio achieved in the second pointing (best-placed compared to the reference stars)
ranged from 15% to an impressive 30%. Preliminary photometric calibration of the first pointing indicates 5σ sensitivities
of Ks~21.75 and H~22.25 (from 22 and 12 min exposures, respectively).
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.
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 2kx2k 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 inclues a LN2 tank and a sptially developed pulse tube cryocooler. 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 (2.2mm).