sine condition


sine condition 

The elimination of distortion and coma in an image is met whenM = n sin u/n′ sin u′ or nh sin u = nh′ sin uwhere M is the lateral magnification, n and n′ the refractive indices of the media in the object and image space, u and u′ are the angular apertures on the object and image sides, and h and h′ the sizes of the object and image, respectively. Syn. Abbé's condition. See angular aperture; coma; correction; distortion.