The rays emanating from any point on a source and travelling different
paths though a spectrometer will not converge to ideal points on
the detector. This divergence (blurring) is called aberration.
The main types of aberration are:
- spherical aberration: some rays focus in line with the
paraxial (design) focal point but focus before or after it;
- coma: some rays focus in the focal plane but are off
to the side of the paraxial (design) focal point;
- astigmatism: some rays focus both not in the focal plane
and off to the side of the paraxial (design) focal point.
For further reading see:
J F James and
R S Sternberg, The Design of Optical Spectrometers,
Chapman & Hall, London (1969).
For a more general but
demanding discussion of optical design see
R R Shannon, The Art and Science of Optical Design, Cambridge University
Press, Cambridge (1997).
First published on the web: 15 March 2000.
Author: Richard Payling