Pre-Focal-Plane

Tunable Atmospheric Dispersion Compensator (TADC)

CONICA shall operate at zenith distances of up to 60 degrees. Atmospheric dispersion compensation to better than 35% (goal 20%) of the FWHM of the Airy disk convolved with the pixel size will be needed, for broad band imaging within any of the I', J, H and K bands, and will be accomplished by the TADC.

The TADC will be removable under remote control from the optical path for observations within the wavelength regions longwards of 2.5um, for narrow band observations or for observations near the zenith.

Calibration Unit

A calibration unit will feed the camera with light for purposes of rough flat fielding and testing of the CONICA functions. The unit will be operated under remote control.

The source is realized by integrating sphere equipped with one halogen continuum source and a spectral calibration lamp. The exit pupil of 1 inch post equipped with a 7.7μm diaphragm is imaged into the CONICA entrance pupil plane via a single CaF₂ lense and a flat folding mirror.