Coma optical aberration

Coma aberration:

Definition of coma aberration:

Spherical aberration that occurs in off axis of an optical system is called as coma aberration.

Optical system with coma aberration:

When all the refracted rays doesn’t passes through the center of focus in non optical axis
results in coma aberration and the below diagram describes how a coma will look like

coma aberration

Properties of coma aberration :

transverse ray aberration for coma

  • Coma has very undesirable characteristics
  • Aberration increases linearly with increase in field angle
  • Comatic image can’t be improved by focal shift
  • In general, Lateral shift too don’t improve the image image quality

Coma aberration free optical system:

This is how an optical system with coma aberration free looks like

coma aberration free

Reference:

James C Wyant, Katherine Creath, “Applied Optics and Optical Engineering,” Academic Press Inc, Vol. XI, pp. 03-39, ISBN 0-12-408611-X, 1992.

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