Photonics Dictionary: P

The underexposure caused by the diffraction of light passing through small openings spaced closely together in masks used in photolithography.

A noncontact sensor used in the remote measurement of position, speed or other variables of moving parts.

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...

A method used to approximate the values of the homogeneous second derivatives at each iteration in the course of lens design and that excels the rate of convergence of the damped least squares method...

In image processing, generating a color image from monochrome data by assigning a color to each of the gray levels.

A means of achieving higher peak powers and more efficient harmonic generation by narrowing the pulse width and thus increasing the frequency bandwidth of the output of CW mode-locked lasers....

A device designed to detect frequency-modulated signals by forming a unidirectional pulse from each sine wave. The direct current of the pulse is proportional to the frequency of the...

A series of capacitors and inductors connected to the flashlamp in a pumped Nd:YAG laser system in order to regulate the pulse shape of the current delivered to the lamp at a given operating voltage.

The use of variations in the power supplied to a laser to change the shape of the output pulse. The technique is used in laser welding, for example, to condition a surface by preheating it at a low...

An instrument designed for laser technology that is used to extract single pulses from the laser and transmit a portion of the pulses, thereby reducing the pulse rate to a desirable frequency.

Variations in a signal passing through an optical fiber caused by the effect on the pulse of the fiber's material and mode propagation characteristics.

A noncontact, nondestructive method of measuring defects in thin composite materials, using a xenon flashtube to generate heat in a sample. A thermal imaging system detects differences in the rates...

A laser that emits energy in a series of short bursts or pulses and that remains inactive between each burst or pulse. The frequency of the pulses is termed the pulse-repetition frequency.

A technique for depositing a material coating on metal, ceramic, semiconductor or polymer substrates. The interaction of laser energy with the target creates a plume of ablated material that is...

1. In the eye, the opening in the iris that permits light to pass and be focused on the retina. 2. In a lens, the image of the aperture stop as seen from object and image space.

Pushbroom scanning is a technique used in remote sensing and imaging systems, particularly in satellite and aerial sensors, to capture images of the Earth's surface or other objects. In pushbroom...

Pyramid error in optics refers to an aberration in the shape of an optical surface, particularly in the context of mirrors. It is a type of distortion that can occur when the surface of a mirror...

Trade name for a type of borosilicate glass manufactured by Corning Glass Works, noted for its low coefficient of thermal expansion. Used most often for mirror blanks; not suitable for light...

Unlike the thermocouple or bolometer, the pyroelectric infrared detector is a current source with an output proportional to the rate of change of its temperature. Capable of extremely rapid response...