What fundamental component did Sir Isaac Newton use in his successful reflecting telescope to circumvent chromatic aberration?

Answer

Mirrors instead of lenses for the primary light collector

Newton demonstrated in 1672 that by using mirrors instead of lenses for the primary light collector, the problem of chromatic aberration could be circumvented because reflection does not separate colors as refraction does.

What fundamental component did Sir Isaac Newton use in his successful reflecting telescope to circumvent chromatic aberration?
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