Additionally , he did fundamental work in the field of optics , invented an improved version of the refracting telescope ( the Keplerian telescope ) .
Additionally , he was mentioned in the telescopic discoveries of his contemporary Galileo Galilei .
Additionally , he did fundamental work in the field of optics , invented an improved version of the refracting telescope ( the Keplerian telescope ) , and was mentioned in the telescopic discoveries of his contemporary Galileo Galilei .