Optics.
the smallest cross section in a beam of paraxial rays, lying in the plane of least spherical aberration.
[ 1865-70 ]
Optics.
the smallest cross section in a beam of paraxial rays, lying in the plane of least spherical aberration.
[ 1865-70 ]
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012