The ideal condition in optical design where all light rays diverging from a single object point converge perfectly to a single image point, without spreading or blurring. Achieving perfect stigmatism across an entire field of view is physically impossible due to inherent lens aberrations, but optical engineers strive to approximate it for the central axis. When a system fails to maintain this property, it introduces blur and distortion.
Heard on the job
The new condenser lens array achieves near-perfect stigmatism at the center, but you still see some coma at the edges.
Do not mix it up with
- Astigmatism: Stigmatism is the ideal focusing of light to a single point; astigmatism is the optical defect where light fails to converge to a single point.