A comprehensive first-order theory of chromatic aberration. Secondary spectrum correction without special glasses

The classical theory of first-order chromatic aberrations neglects terms of paraxial order in aperture and powers higher than the first in glass dispersions. This has led to the erroneous conclusion that secondary spectrum correction requires the use of special optical materials. A comprehensive first-order theory, which includes these missing terms, is developed in a form adapted to the designing of optical systems. There follows a discussion of the conditions for secondary spectrum correction with common glasses.