PI: Daniel Fabricant
Project Engineer: Robert Fata
The Wide Field Corrector consists of a group of lenses that
remove off-axis aberrations at the f/5 focus of the converted MMT, allowing
the telescope to offer excellent images over a very large field.
The Wide Field Corrector has two modes of operation. It can be used for
wide field spectroscopy, in which case it has a 1° diameter field.
The spectroscopic field is curved (8 mm sag) but highly telecentric.
In its imaging mode, the corrector has a 0.5° diameter field and a flat
The system works over the 320 to 1800 nm range, but the
anti-reflection coatings are optimized for the 320 to 1000 nm range.
Atmospheric dispersion compensation prisms are included in the spectroscopic
Sol-Gel anti-reflective coatings have been applied to the lenses and ADC
prisms by Cleveland Crystals.
As of June 18, 2003 commissioning of the f/5 secondary and
the spectroscopic mode of the f/5 corrector (1 degree field) has been
completed. All of the optics have the correct surfaces and are
located correctly. On-axis, the best images that we have recorded
have 0.4 arcseconds FWHM. At the edge of the spectroscopic field
the best recorded images have 0.5 arcseconds FWHM, near the limit
allowed by the optical design. Commissioning of the imaging configuration
the corrector followed in November 2003 with the commissioning of Megacam.
Megacam has achieved 0.4" images across the full 24' x 24' field of view.