A point source of light used for the test and evaluation of image quality. May be a backlit pinhole in an otherwise opaque sheet placed at an appropriately large distance from the lens being tested.

The point spread function (PSF) is a fundamental concept in imaging that describes the response of an imaging system to a...

The visual examination by a trained observer of the image of a point source. Any coloring or departure from the Airy disc...

A test for spherical aberration, coma or astigmatism in which incident rays from a point source are isolated by small holes...

The Foucault test is performed by moving a knife edge laterally into the image of a small point source. The eye, or a...

Two plane mirrors that are not wholly located in the same plane. When light from a point source or slit reflects from the...

The law stating that the illuminance (or irradiance) from a point source varies as the inverse square of the distance...

An optical device that produces a line image lying along the axis from a point source of light; therefore, it has no...

The figure seen through or imaged by an optical system. It may contain structures, natural or artificial, or it may be the...

The image of a point source that appears as a circle of finite diameter because of defocusing or the aberrations inherent in...

The distribution of energy about the image of a point source in the focal plane of an optical system.

A lamp, usually incandescent, that has a very compact filament, permitting a greater concentration of emitted light, aided...

An imaging technique in which an object moving through an interference field formed in space scatters light and is spatially...

A method of demonstration or examination using a point source illumination without the use of any projection lens between...

SI unit of luminous intensity. It is defined as one sixtieth the normal intensity of one square centimeter of a blackbody at...

A radiation source that, unlike the point source, can be resolved by the naked eye into a geometrical image.

Condition in which a perpendicular surface can be discovered for every ray in a group. This condition is commonly observed...

Totally coherent radiation is produced by a purely monochromatic point source. In the real world the energy will have a...

Seidel aberrations refer to a set of monochromatic aberrations in optical systems, named after the German mathematician and...

1. With respect to angular subtense, a source of light, such as a star, that is very small. In a lab, a point source may be...

Celestial point sources that emit specific wavelengths of radiation that appear on spectral charts as narrow lines. The term...

A method of producing magnified images by x-rays. The specimen is placed close to a point source of x-rays; the...

A cylindrical lens that may be rotated to distort a bundle of light originating at a point source, to form a line image.

The position and shape of the image of a point source, as predicted by geometric optics alone. The geometric image is to be...

A narrow cone of light rays that diverge from a point source or converge to an image point.

A bright spot or point, due to Fresnel diffraction, that appears at the center of the shadow of a circular object in light...

A series of permanent holograms in dichromated gelatin formed by opening total page-composer apertures and setting a point...

A measure of image quality produced by an optical system. May be specified in terms of cycles per millimeter, referencing a...

A small bulb containing a conducting gas, an arc being formed between a metal ring and a tiny zirconium electrode near the...

A lumen is a unit of measurement used to quantify the amount of luminous flux, which is the perceived power of light. In...