Photonics Dictionary

A filter that is transparent to shorter wavelengths, but opaque to longer wavelengths.

A filter designed to decrease the luminosity of the sky without decreasing that of the landscape in the foreground. A filter that has a depth of tint that decreases from top to bottom is used in...

Blocking by means of a pitch ring, pitch button or a totally pitched block. Pitch, containing a soft filter, may be used between the optical components to bar lateral movement.

A filter that creates spherical aberration resulting in an image with a soft outline.

A solar simulator is a device used to replicate the spectrum and intensity of sunlight in a controlled environment for testing and research purposes. Solar simulators are employed in various...

A type of birefringent filter, similar in principle to the Lyot filter, consisting of many identical birefringent elements, often arranged in a "fan" or "folded" configuration, positioned between two...

1. Generally, an emulsion mask having a clean annular region in an otherwise opaque region. It is designed to eliminate undesired information. 2. A pinhole in a metal plate, placed at a focal plane...

In image processing, the enhancement of an image by increasing or decreasing its spatial frequencies.

Spectral flow cytometry is an advanced flow cytometry technique that expands the capabilities of traditional flow cytometry by utilizing spectral information from fluorochromes to enhance...

Any pyrheliometer that has a filter placed over its sensor to limit the range of solar radiation it will detect; used to determine the distribution of solar radiation over its visible and into its...

A multilayer filter that passes only a narrow band of wavelengths.

A neutral density filter that, when placed in front of the iris of a lens, increases the f-stop range.

The basic process of color photography whereby colors are subtracted from white light by means of filters, making all colors and intensities available.

An instrument consisting essentially of a photoelectric cell filtered to respond to a specified wavelength region, an amplifier of sufficient gain to provide power enough to control movement of a...

A thin layer of a substance deposited on an insulating base in a vacuum by a microelectronic process. Thin films are most commonly used for antireflection, achromatic beamsplitters, color filters,...

Thin-film coatings are layers of material applied to the surface of an object or substrate, typically to modify its optical, electrical, or mechanical properties. These coatings are composed of thin...

Integral densities that are measured relative to arbitrarily selected red, green and blue filters.

A laser capable of generating light pulses that last only a few femtoseconds. This can be achieved by nonlinear filtering to increase bandwidth and compress the pulse or by passive mode-locking or...

A filter that is opaque from 200 to 400 nm.

Equipment dependent on the effects of a vacuum. The principal applications in optics are in the coating of lenses and substrates and the fabrication of multilayer interference filters.

A filter, pale purple in color, used in black and white photography to display the brightness values of a subject being recorded on film.

Volume Bragg gratings (VBGs) are specialized optical elements that consist of periodic variations in refractive index throughout the volume of a transparent material, typically a photosensitive glass...

A waveguide is a physical structure or device that is designed to confine and guide electromagnetic waves, such as radio waves, microwaves, or light waves. It is commonly used in communication...

An optical filter so constructed that the density increases progressively from one end to the other, or angularly around a circular disc.

Whispering gallery mode (WGM) refers to a phenomenon in wave physics, particularly in optics, where waves, such as light or sound waves, are trapped and circulate along the periphery of a curved...

Wide-field fluorescence microscopy uses either naturally occurring structures or staining with fluorescent tags that are activated by specific wavelengths of light and then emits a different...

A method that embraces the classical approach to image restoration and attempts to minimize the mean square difference between the original ungraded signal and the restoration.

A window made of glass containing a high percentage of lead or other dense material known to absorb x-rays readily.

The introduction of a filter into an imaging system to implement a phase contrast for an intensity mapping of a pure phase image.

The removal of the zero-order component of the Fourier spectrum distribution of an object with a small, opaque absorber or reflector in the Fourier plane, to produce images that appear bright on a...