"Dispersive" Quotes from Famous Books
... unite in the axis point O'1; and those under an angle u2 in the axis point O'2. If there be refraction at a collective spherical surface, or through a thin positive lens, O'2 will lie in front of O'1 so long as the angle u2 is greater than u1 ("under correction''); and conversely with a dispersive surface or lenses ("over correction''). The caustic, in the first case, resembles the sign > (greater than); in the second K (less than). If the angle u1 be very small, O'1 is the Gaussian image; ... — Project Gutenberg Encyclopedia |