He developed the first reflecting telescope, which featured a concave mirror, a flat mirrow & an eyepiece
Many types of telescopes were developed in the 20th century for a 
wide ... spectacles for correcting long sightedness with convex lenses were 
invented in .... Newton's first compact reflecting telescope had a mirror diameter 
of 1.3... [DOC] [TLE] The Early Reflecting Telescope:Cassegrain, Mersenne, and Cavalieri [PAR] The builder of that first crude telescope, Nicolo Zucchi, and the scientist who 
published ... Isaac Newton developed the design for his reflecting telescope in 
1668 (see ... reflects the light back through a hole in the primary mirror to an 
eyepiece.