Photonics Dictionary: Z

Spherical or chromatic aberration in a lens having a wide aperture. It is present because the refracting power varies for different zones concentric at the axis. This is the residual when the lens...

A factor that, when multiplied by the average candlepower emitted by a light source in a specified angular zone, reveals the lumens in the zone.

A grating that specularly reflects the specified long radiation wavelengths and diffracts the shorter wavelengths off in known directions, eliminating the interference of randomly scattered radiation.

Schott Glass Technologies' trade name for a glass-ceramic material with a very low coefficient of thermal expansion.

The difference in electrokinetic potential between the stationary liquid connected to a solid phase surface and the mobile portion of the liquid's diffuse layer.

Also known as zonal axis. The axis positioned through the center of a crystal that is parallel to a zone edge.

A plate of glass, usually a photograph, on which there is a central spot surrounded by concentric annular zones, alternately opaque and transparent, the radii of the boundaries between the zones...

An optical system of variable focal length, the focal plane remaining in a fixed position. This result is achieved by moving some of the components of the system along the lens axis, other components...