Photonics Dictionary: O

Off-axis paraboloid and ellipsoid mirrors are specialized optical components used in various optical systems, particularly in applications requiring precise focusing, collimation, or imaging of...

A prism or prism assembly that serves to displace the instrument's optical axis.

The electrical resistance between two points of a conductor when a constant difference of potential of one volt, applied between these points, produces in this conductor a current of one ampere, the...

A form of high-power microscope objective where the space between the object and the first element is filled with an oil having the same index as that element. This form reduces losses, increases the...

A polished plano-parallel plate that is contacted to an unpolished glass surface to permit see-through analysis of the material. The plate eliminates effects because of the surface quality of the...

Oleophobic is a term used to describe substances or materials that repel or resist oils. The word oleophobic comes from the Greek words "oleo," meaning oil, and "phobos," meaning fear. Oleophobic...

A glow discharge tube placed on an insulating rod to detect the presence of high-frequency radiation in the vicinity of a transmitter. The tube indicates the presence of the radiation by the glow...

An instrument for measuring opacity.

A measure of a material's inability to transmit light, equal to the reciprocal of its transmittance.

A material consisting of very small colorless particles imbedded in a clear glass matrix. It is available in two forms: flashed opal and pot opal. The flashed variety consists of a rather thin layer...

A tungsten filament lamp that uses an opal glass bulb to diffuse light.

A term describing a substance that is impervious to light; the characteristic of a substance that has no luminous transmittance.

An opaque projector is a device used for enlarging and projecting images from opaque objects such as printed pages, photographs, or three-dimensional objects onto a screen or surface. Unlike a...

A bubble at a polished surface that has been opened by grinding or polishing.

An interface in an optical network that permits an optical signal to pass without changing the optical signal to an electrical signal and therefore does not limit the signal to a specific protocol.