Photonics Dictionary

A point cloud is a set of data points in a three-dimensional coordinate system, where each point represents a specific location in space. These points are typically obtained through various sensing...

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 simulated by imaging a large source onto and through a pinhole, or by...

An established point on which the observer's eye is focused.

In digital image processing, a subcategory of frame processing that transforms pixel brightness and contrast through use of a mapping function. Point processing can be single-image (simple contrast...

A lamp, usually incandescent, that has a very compact filament, permitting a greater concentration of emitted light, aided by the use of small apertures and appropriate reflectors.

The point spread function (PSF) is a fundamental concept in imaging that describes the response of an imaging system to a point source or point object. It characterizes how a single point of light is...

A crystal diode whose rectifying activity is determined by the touching of the crystal to a finely pointed wire surrounded by a material of opposite type.

A device used in solar systems to direct mirror-reflected sunlight to a heat absorber and heat-driven engine, which turns a generator to produce electricity.

A method of producing magnified images by x-rays. The specimen is placed close to a point source of x-rays; the magnification achieved is the ratio of source-image to source-object distance....

A Huygenian eyepiece containing a pointer at its focal plane that is used -- when viewing an object through the eyepiece -- for specific designation.

A device attached to the end of an alignment telescope that detects and calculates a plane mirror's rotation axis that is perpendicular to the line of sight. The device is adaptable for evaluation of...

Location on the CIE chromaticity diagram which produces the color white for a given light source at a specified temperature.

The point to which the extension of the straight line, reaching from the sun to the observer's eye after penetrating the atmosphere of the Earth, is projected.

Aplanatic points refer to specific points in an optical system where certain aberrations, such as spherical aberration or coma, are minimized or eliminated. In an optical system, aberrations are...

Focal, nodal or principal points of a lens. If the respective distances of the object and image are measured from the cardinal points, all thin-lens equations are applicable to thick lenses.

A device for obtaining very low crosstalk in a crosspoint by arranging two simple switches along different arms of a passive crossover and connecting the switches with a curved connecting guide to...

The two points on the principal axis of a mirror or lens so positioned that light emitted from either point will be focused at the other, i.e., object and image points.

A pixel-based computer graphics system that simulates the tools of an artist.

The object distance at which the eye is focused with the eye lens in a neutral or relaxed state.

One or more spots placed in the field of view of an optical system to provide a means of reference.

The principal point of a lens relative to the object space.

That point on the optical axis of a lens, to which an incident bundle of parallel light rays will converge.

1. The value on either the leading or the trailing edge of a laser pulse at which the power is one-half of its maximum value. 2. The wavelength at which a filter is transmitting one-half of its peak...

Handheld optical laser device containing a semiconductor or DPSS source. The output is corrected via internal collimating optics. For typical use the output is reduced to eyesafe operation power. (5...

The temperature at which the solid phase of a material is in equilibrium with the liquid phase, or when the material changes from a solid to a liquid.

The closest distance to which the eye can focus on an object, normally taken to be 250 mm. The near point varies with age.

Of all the rays passing through a lens from an off-axis object point to its corresponding image point, there is always one ray whose direction in the image space is equal to that in the object space....

In a fiber optic guided missile, the point at which the optical fiber pays out from the bobbin on which it is wound.

The intersection of the principal plane and the optical axis of a lens.

A device used to project a small area of light on a screen for indication.

The point of a chromaticity diagram that represents the chromaticity of a reference stimulus.

On a chromaticity diagram, the point that denotes the chromaticity sample.

The principal point of a lens relative to image space.

Diamond turning, also known as diamond machining or diamond cutting, is a precision machining process used to produce high-quality optical surfaces and components with extremely tight tolerances. It...

3D Laser Triangulation - A technology that allows sensors to probe the surroundings. Laser triangulation systems have an ideal operating point, or the standoff distance, where its reflected spot is...

The value of the distance of distinct vision, minimum focusing distance or near point, divided by the focal length of the lens. Magnification is produced when the optic is placed at its focal...

The measurement of heat energy as determined from absolute zero as the zero point on the scale. Increments are identical to the Celsius as well as Kelvin scales.

An absorption peak refers to a sharp increase or spike in the absorption of electromagnetic radiation at a particular wavelength or energy level. It is a distinctive feature in the absorption...

An achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

That point in the electromagnetic spectrum at which an optical system focuses the most chemically effective rays.

In aerial photography, the geometric method of indicating the three-dimensional location of ground points from a pair of aerial photographs.

An optical system with object and image points at infinity. Literally, "without a focal length."