Published online by Cambridge University Press: 12 April 2016
I wish to begin by saying a few words on an instrument which has been utilized thus far only to observe the sun, with a very small telescope of about 5cm diameter. This may appear to stand far away from the main topic of this meeting but in fact, the scientific program which is successfully being developed on the sun would be of major interest for stellar astronomy if it could be extended to at least a few bright stars. I will therefore describe also a possible extrapolation of an instrument to be used on the largest available telescopes for stellar observations.