Scuderi S., Cecconi M.

The BBI (Broad Band Imager) for EST will be one of the 'first light' instruments of the telescope. The scientific objectives will be the the study of fundamental astrophysical processes at their intrinsic scales in the Sun's atmosphere, and this goal will be reached with an instrument able to obtain diffraction limited images over the full field of view of EST at multiple wavelengths and high frame rate. The BBI will cover the 390 to 900nm wavelength range, using two different arms(390-500nm and 600-900nm), and three different channels. Each subchannel will be further split in thre subchannels, each one served by a different 4kx4k detector; one subchannel will be dedicated to chromospheric observations with narrow band filters, the second one for photospheric obeservations with wide band filters, and the third one with the same filters, used out of focus for phase recostruction. The total number of foreseen filters will be 11, with bandpasses FWHM from 0.05 to 0.5 nm. The instrument will exploit the diffraction limited quality of the telescope, and will operate in two modalities: maximum field (2'x2'), and high resolution (better than 0.04" at 500nm).