Answer to Question #195 in Optics for Liset

Question

If a plate of Iceland spar is put onto a page of printed text, the split of letters occurs. Will there be a doubling of the image, if you look through the same plate at a distant point?

Answer 1

Doubling will take place, but it will be very small, and even smaller then the ratio of the thickness of the spar to the distance to the object. In the limit of infinitely remote subject the dichotomy tends to zero (in fact, zero will be only when the distance to the subject is of much greater than the thickness of the spar).