Definitions: P

A whole-flow-field technique providing instantaneous velocity vector measurements in a cross-section of a flow that is seeded with micron-sized particles. CCD or CMOS cameras and laser light sheets...

A planar photocathode and a planar phosphor screen mounted in a close-spaced parallel configuration in an evacuated enclosure so that the ensemble of photoelectrons emitted from each photocathode...

An image that is reversed contour or inside-out.

The finite amount of electrical charge generated in response to incident radiation and transferred from one storage element to the next in a charge-coupled device. Each packet corresponds to a pixel...

A camera designed to form a continuous record of an expansive section of the horizon. The typical panoramic camera is mounted to rotate about a vertical axis. A slit opening in the film plane and the...

The image distortion produced by a panoramic camera with a swinging lens or a swinging mirror in front of a fixed lens. The magnification is greatest in the center and diminishes to each side in the...

A lens system that is capable of producing a 360° image, or one that is very close to that. In recording, the image may be formed on a curved strip of film surrounding the lens, resulting in a...

A telescope so manufactured that the image remains erect and the position of the eyepiece is unchanged as the line of sight is pointed in any horizontal direction.

A concave mirror that has the form of a paraboloid of revolution. The paraboloidal mirror may have only a portion of a paraboloidal surface through which the axis does not pass, and is known as an...

The optical phenomenon that causes relative motion between two objects when the eyepoint is moved laterally. When parallax appears in a telescope between the image and reticle, this indicates the...

Parallel scanning refers to a method of acquiring data or images simultaneously from multiple sources or in parallel, rather than sequentially scanning each source one after another. This approach is...

In a camera or cathode-ray tube, distortion that is designated by a lateral skewing of the reproduced image.

One eyepiece of a set having equal distances from their mounting interface to their image plane, permitting freedom to interchange eyepieces without the need to refocus.

An array of lines in the infrared region of the emission spectrum of atomic hydrogen. Their wave numbers are expressed by the equation: where represents the wave number in the reciprocal centimeters,...

A prism made up of two air-spaced components. It has the ability to revert, and not invert, an image, and can be used in convergent, divergent and parallel light. May be rotated to compensate for...

A thin, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter, for example, in a color camera; it is so thin that no perceptible image doubling...

A five-sided prism containing two reflecting surfaces at 45° to each other, and two refracting faces perpendicular to the entering and emerging beams. The deviation angle of 90° is...

A source of light will not cast a distinct shadow of an interfering, opaque object, but will cast a shadow having two parts: 1. the umbra, or the central, totally dark part of the shadow; and 2. the...

A theoretical, ideal lens capable of producing perfect images. Used as a lens design and analysis tool to image collimated output from an afocal system.

In a charge-coupled device, the detection of charge collected by the transport register rather than by the image-sensing elements.

An optical instrument designed to displace the line of sight in a vertical direction. For submarines and other military uses the periscope is a long tube containing prisms at both ends and...

A high-speed, narrow-field lens consisting of two achromats spaced about the aperture stop. Its uses include portrait photography and motion picture projection.

A paraboloidal surface on which the image is located when there is no astigmatism.

In optics and photonics, "phase" refers to a property of electromagnetic waves, such as light, that describes the position of a wave at a given point in time within its oscillation cycle. More...

Phase contrast microscopy is an optical microscopy technique that enhances the contrast of transparent and colorless specimens, making it possible to visualize fine details and internal structures...

In optics and photolithography, a phase mask refers to a device that modifies the phase of light waves passing through it. The phase mask is used to control the spatial distribution of the light's...

The determination of the relative phase shift of an image as a function of frequency. A phase change of 180° with respect to the object results in an image with the black and white areas...

Microscopy technique to convert the phase structure of the wave transmitted or reflected by the specimen into a corresponding intensity structure in the image plane.

A microscope that has an annular stop in the lower focal plane of the condenser, and a quarter-wave retarding and absorbing ring in the upper focal plane of the objective that just fills the image of...

A process used in pyrometry and photothermometry to create a photographic record of a surface's temperature gradients. Essentially, it involves the exposure of a glowing phosphorescent surface to the...

Abbreviated PAI. An imaging modality with a hybrid technique based on the acoustic detection of optical absorption from endogenous chromophores or exogenous contrast agents. Light is absorbed by the...

Photocathodes are specialized materials or surfaces that exhibit the photoelectric effect, wherein the absorption of photons leads to the emission of electrons. When photons with sufficient energy...

A photodetector, also known as a photosensor or photodiode, is a device that detects and converts light into an electrical signal. Photodetectors are widely used in various applications, ranging from...

A device consisting of a microammeter, a photovoltaic cell and a battery. It is used for the measurement of scene brightness and the determination of correct exposure for photographic processes.

Photogrammetry is a technique used to obtain accurate three-dimensional measurements of objects and environments through the analysis of photographs or imagery. It involves extracting information...

The measurement of the responsivity of photographic media and of the relations between exposure and density of developed images.

Photolithography is a key process in the manufacturing of semiconductor devices, integrated circuits, and microelectromechanical systems (MEMS). It is a photomechanical process used to transfer...

A still or motion-picture camera designed to photograph through a microscope. Photomicrographic equipment usually contains a beamsplitter or other means for simultaneously viewing, orienting and...

A photon sieve is an optical device used in the field of optics and imaging. It's designed to focus and shape light, typically for applications such as imaging or microscopy. The photon sieve...

Photon-rich typically refers to an environment or situation where there is an abundance of photons present. In the context of optics, photon-rich environments are those where there is a high density...

Noise created by patterns imaged on a CCD surface. Pixel sensitivity is altered by responsivity during illumination.

A small section of the surface of a sensor corresponding to a single pixel in the image.

A type of copying camera in which the object is placed on a horizontal easel and photographed by a horizontal camera above the easel through a 90° reversing prism. The image is recorded on a...

A document-transmitting process that uses a cylinder that rotates the document to be scanned and detected by a photoelectric cell. The cell transforms the light into electrical energy that may be...

Phototheranostics, a portmanteau of "photo" (light), "therapy," and "diagnostics," refers to an emerging field that combines therapeutic and diagnostic capabilities in a single platform, often...