Definition of "aplanat" in English

noun

1. (optics) A lens that has been corrected for spherical aberration and coma in order to produce a rectilinear image.

   • 2009, Gérard René Lemaitre, Astronomical Optics and Elasticity Theory, Springer, Astronomy and Astrophysics Library, Corrected 3rd printing, page 11, […] which is totally false since he established the algebraic conditions for thin-lens achromatic aplanats;