Photonics Dictionary: P

A device that couples a light source to an optical fiber by projecting an image of the source and the fiber core onto a screen where they can be superimposed by micropositioners.

A contour mapping technique that involves projection of a grating onto an object to produce a shadow grating that is observed through another grating. Therefore, the size of the object to be measured...

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

The measurement of surface temperature by a thermograph that forms a pattern of the heat radiated by the surface on a luminescent screen.

A microscope that uses an extremely fine x-ray focal point to produce an enlarged photographic image of a sample. Also known as an x-ray shadow microscope.

The minimum amount of strength characteristic of an optical fiber, as determined by proof stressing; expressed in thousands of pounds of pressure per square inch.

A means of testing the strength of optical fibers to ensure reliability, by applying stress to the fiber so that any flaws generated during manufacturing or handling result in breakage of the fiber.

An assembly of prototype instruments, equipment and/or software designed to perform all the functions of a concept or idea which, when operated as a system, produce evidence, results or data...

For an electromagnetic field mode varying sinusoidally with time at a given frequency, the logarithmic rate of change, with respect to distance in a given direction, of the complex amplitude of any...

The removal of a sharp edge on an optical element by grinding, to prevent accidental chipping of that edge during subsequent handling.

A film applied to a coated or uncoated optical surface primarily for protecting this surface from mechanical abrasion, from chemical corrosion, or from both. For example, a thin layer of silicon...

Technique using a fiber optic assembly to illuminate an opaque object and transmit an image back from it without a lens system on the distal end.

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 of sensing by transmitting energy from the sensor and detecting the energy after it has been reflected by the object in its path.

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.

Coded image obtained optically with a nonredundant pinhole array imaging aperture.

An image that is reversed contour or inside-out.

An astronomical body that emits radiation concentrated by a strong magnetic field into two beams that rotate, giving a pulsing effect.

The compression and intensification of a laser pulse of a specific width into a smaller pulse width. A spherical cavity, in conjunction with a beam compressor, is efficient for pulse amplification....

The instrument used to analyze a pulsed electromagnetic wave to determine its time, amplitude, duration and shape, and to display this information in some appropriate form, either visually or...

System of information coding in which the signal is sampled 8000 times per second and the samples quantized by referring them to a series of preset 8-bit codes. Thus digitized, the signal is sent to...

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...

The lifetime of a laser pulse, generally defined as the time interval between the halfpower points on the leading and trailing edges of the pulse.

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.

Factor that relates the pulse spread occurring in a graded-index fiber to that of an equivalent step-index fiber having an identical refractive index difference between core and cladding (that is, an...

Number of pulses emitted per unit of time by a pulsed laser.

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...