SHARP II+ is a near infrared camera which has been specially designed for the use with the adaptive optics system ADONIS, profiting from the experience gained with the speckle camera SHARP I operated at the NTT and a previous version of a dedicated adaptive optics camera SHARP II.
SHARP II+ is a camera for diffraction limited imaging in the spectral
range from 1.1 to 2.45 , using a Rockwell NICMOS 3 array (HgCdTe,
elements) as detector and supplying three image
scales of 35, 50 and 100 mas/pixel. A cold shutter allows to use
integration times down to 20 ms for bright sources. A Lyot stop
reduces the background radiation produced by the telescope and the
optical components in the beam. For photometry, standard bandpass
filters (J, H, K and K') are available. Low resolution spectroscopy is
provided by a set of narrow band filters (R
100) at selected
line positions and a CVF (Circular Variable Filter, R
60)
for the 1.4 to 2.4
range. The CVF is also used as an order
selector for two K-band Fabry-Perot etalons with spectral resolutions
of 1000 and 2200 respectively. A wire grid polarizer can be inserted
into the beam in front of the camera. For highest resolution imaging
in J- and H-band, an atmospheric dispersion corrector is available.
Figure 1.1: The concept of SHARP II+