Photonics Dictionary: F

Unit of luminance equal to 1/p candela per square foot. (fl).

In a lens, the square of the radius of its aperture divided by the product of the focal length and the wavelength. It measures the importance of diffraction in the image formed by the lens. A small...

The simultaneous collection of two or more signals at a single location. In a digital computer, it refers to the number of inputs that can be accommodated by a particular logic circuit.

The distribution of one signal to more than one location. In a digital computer, it refers to the number of outputs that can be fed by a particular logic circuit.

The signal-to-noise ratio (SNR) obtained with a Fourier transform spectrometer when detector noise prevails, which exceeds the SNR of a scanning spectrometer in the same time by a factor proportional...

The principle that a light ray extending from one point to another will, after any number of reflections and refractions, follow the path requiring the least transit time. This is also known as the...

A fiber laser is a type of laser in which the active gain medium is an optical fiber doped with rare-earth ions such as erbium, ytterbium, or neodymium. Fiber lasers generate coherent light through...

A package for an optical fiber or fibers that may include cladding, buffering, strength members and an outer jacket.

A fiber optic imaging bundle is a specialized optical device composed of multiple optical fibers bundled together. Each fiber optic strand within the bundle acts as a conduit for transmitting light....

The number of fields scanned per second in a television system. The US standard is 60. Also called field frequency.

Filoviruses are a family of viruses that are responsible for severe and often fatal hemorrhagic fevers in humans and non-human primates. The name "filovirus" is derived from their filamentous...

A device that holds a number of filters and allows the filter with the desired characteristics to be rotated into an optical aperture.

A finite version of Shannon's sampling theorem that states that a class of functions can be reconstructed exactly by a sufficient number of spectral samples; the reconstructed function is an explicit...

Any of a number of instruments that uses a flame to vaporize a solution of the chemical being analyzed so that light may be passed through the vapor. Monochromation of the transmitted light is...

Optical glass that possesses a refractive index equal to or less than 1.5, and an Abbe number that ranges from 62 to about 85.

A device, also called a fluorescence lifetime instrument, that measures decay curves of fluorescing samples. It generally consists of a gated pulsed flashlamp or a cavity dumped dye laser...

A solid-state laser consisting of active atoms or ions of a transition metal, rare-earth metal or actinide, imbedded in a crystal or glass material, often garnet. Excitation and transfer to different...

The number of times per second that the frame of a television system is completely scanned. In the United States, 30 per second is the standard frame frequency.

The number of separate images exposed by a cine camera in a second or the number illuminated by a cine projector in a second. By varying the number of images recorded per second, films can be created...

With reference to electromagnetic radiation, the number of crests of waves that pass a fixed point in a given unit of time, in light or other wave motion. Expressed in hertz or cycles per second.

The number of electrons that each pixel of a charge-coupled device can hold without overflowing and causing blooming.