Conoscopic optical systems use a specialized converging lens to map the angular distribution of light onto a two-dimensional focal plane. Instead of moving a detector around a light source mechanically, the lens captures light emitted or reflected from a wide cone of angles all at once. This technique is heavily used in display metrology and advanced scatterometry to rapidly measure luminance and chromaticity across different viewing angles.
We need to run a conoscopic measurement on the new panel to check for color shift at extreme viewing angles.
Conoscopic lenses are often called Fourier lenses because they perform an optical Fourier transform, mapping the emission angle directly to a spatial position on the sensor.
Related terms
Goniophotometer
An instrument that measures a luminaire's light intensity in every direction by turning the luminaire, or a mirror around it, relative to a detector.
Luminance
The brightness of a surface or source as seen from a particular direction, measured in candelas per square meter.
Focal plane
The flat surface perpendicular to the optical axis where an image is sharply formed.