Definitions

That object distance at which a camera must be focused so that the far depth of field just extends to infinity. The near limit of the depth of field is then half the hyperfocal distance. For normal...

A system that transmits and receives identification codes to facilitate the discrimination between enemy and friend in a tactical situation.

The processing of an image or portion of an image by transform coding and analysis. Fourier, Hadamand, Kronecker and Eigenvector transforms are applicable to image transformation.

In a camera, the movement of one or more lenses behind the front lens, rather than of the front lens itself, to bring the subject into focus. Because internal focusing does not require the front lens...

Also known as gas focusing. The introduction of an inert gas into a cathode-ray tube for the concentration of the electron beam. The gas molecules are ionized by the electrons, producing a core of...

A device consisting of two optical systems in which two signals are simultaneously transformed to produce their spectra, and these spectra are multiplied and inversely transformed to produce the...

Lens which, by altering the phase, efficiently images through a holographic process.

A computer-generated kinoform used for data processing because of its use of incoherent light and its wide field of view, which facilitates parallel processing of two-dimensional data.

Base area of a laser unit.

A hologram formed without lenses and with the object and reference points sharing the same plane. In the initial recording, each object point produces fringes having one spatial frequency across the...

The apparent visual angle that divides intrabeam viewing from extended-source viewing.

One class of nonlinear space-invariant transformation processes used for processing convolved and multiplied signals.

The force acting upon a charged particle as it moves in a magnetic field, proportional to the particle's charge and velocity.

A variation of the atomic force microscope that operates by scanning a tiny ferromagnetic probe (or a magnetized tip) over a magnetic sample, and detecting the extremely small forces exerted on the...

A vacuum tube in which a magnetic field is superimposed onto the tube's electrical field. When the two fields are aligned, electrons from the photocathode are accelerated through the tube in a spiral...

In the context of thin film deposition processes such as evaporation or sputtering, masks are used to selectively deposit material onto substrates, creating patterns or structures with precise...

A form of an element that cannot demonstrate optical activity as a result of dextrogyrate and levogyrate effects that are balanced contrary to each other in a structure. In essence, meso form...

A lens with internally adjustable elements to produce a range of focal lengths. Unlike a true zoom lens, a multifocal lens must be refocused each time the focal length is changed. See variable-focus...

The optical Fourier transform is a mathematical operation applied to optical signals that involves transforming a spatial domain representation of an image into its corresponding frequency domain...

A technique for detecting and measuring atmospheric pollution, in which an oscillating mirror directs half the incoming light to a transducer that controls amplitude and frequency, and the resulting...

Focus derived from paraxial data.

Having coincident focal points.

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.

Lenses that have identical flange focal distances and can be interchanged.

The focusing of an electron beam by a magnetic field that permanently retains the majority of its magnetic properties.

The force that stimulates the emission of an electrical current when photovoltaic action creates a potential difference between two points.

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

A manufacturing process used to construct substrates for large optical components. Used with IR materials, planform bonding permits the joining of several smaller pieces to be used in place of a...

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 thermoplastic, self-extinguishing polymer with excellent high-temperature, low-creep and arc resistance properties.

A glass structure from which an optical fiber waveguide may be drawn.

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 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 transform defining that, if a reference beam is a divergent spherical wavefront, then the reconstructed image will be the equivalent of the near-field diffraction pattern of the object. Also...

A type of internal focusing in which only the lens elements closest to the rear of the lens barrel are moved.

The ratio of the first focal length of a lens to the refractive index of the medium containing the incident light; the ratio of the second focal length to the refractive index of the medium...

Reflectance confocal microscopy (RCM) is a non-invasive imaging technique that allows for high-resolution, in vivo imaging of biological tissues at the cellular level. It is particularly useful in...

Also known as reversed telephoto lens. A lens consisting of an ordinary objective with a negative component near its front focal point. Thus, the back focus is large, relative to its focal length....

Derived from "self-focusing,'' Nippon Sheet Glass Co. (NSG) of Japan's trade name for graded-index fiber rods with parabolic index profile, suitable for use as cylindrical microlenses.

An aperture consisting of a semitransparent central region whose amplitude transmittance only is varied, and the relative phase difference between the central and annular region is fixed as p -...

A crystal, glass, or quartz slicing and cutting machine is a specialized piece of equipment used in the manufacturing process to precisely cut and slice materials such as crystals, glass, and quartz...

A filter that creates spherical aberration resulting in an image with a soft outline.

A lens that exhibits spherical aberration when used at large aperture settings, and that forms an image with a slightly blurred outline.

When splitting the output of a single optical fiber into two or more fibers, the difference in the maximum loss between any two channels.

A platform mount used to hold sensitive optical instruments immobile.

The graph of the oscillating variations composing the wave of a video signal.