An aplanat is a compound lens system engineered so that parallel rays of light converge to a sharp point, even off the central axis. By correcting for spherical aberration and coma simultaneously, it produces a flat, undistorted image over a wide field. Engineers specify these lenses for critical imaging applications where edge-to-edge sharpness is required.
Heard on the job
We swapped the standard singlet for a custom aplanat to get rid of the comet tails on the off-axis spots.
Also heard as
- aplanatic lens
Do not mix it up with
- Achromat: An aplanat corrects for geometric distortions like coma, while an achromat corrects for color fringing.
Related terms
Aplanatic
Characterized by the absence of spherical aberration and coma in an optical system.
Aplanatism
The optical condition of being free from spherical aberration and coma.
Spherical aberration
An optical defect where light rays passing through the edge of a lens focus at a different point than central rays.