Definitions

That branch of spectroscopy that applies to the study of interactions between energy and atomic nuclei. The simultaneous application of a strong magnetic field and the radiation from a...

A phenomenon, exploited for medical imaging, in which the nuclei of material placed in a strong magnetic field will absorb radio waves supplied by a transmitter at particular frequencies. The energy...

A chemical detection technique used to measure molecules that have a magnetic dipole moment. The analysis is directed to nucleuses which have a quadrupole moment which leads to an asymmetric electric...

A photographic emulsion of the silver-halide type that is used to record the path of a charged traveling particle. The tracks recorded on these emulsions are typically observed under a microscope...

A plane along which destructive interference takes place.

A lens used in the optical testing of an aspheric surface. It converts a spherical wavefront into one that precisely matches the surface under test. When the wavefront is reflected from that surface,...

Commonly performed in spectroscopy, the optical null process is a method for radiation detection whereby physical detectors are used to rapidly interchange the intensity between a reference beam and...

The sine of the vertex angle of the largest cone of meridional rays that can enter or leave an optical system or element, multiplied by the refractive index of the medium in which the vertex of the...

Expression of the nondimensional coefficient of the heat transfer in a convection process.

In image acquisition (and sampling theory), the postulate that the pickup sampling frequency must be a minimum of twice as high as the Nyquist rate of brightness change of any detail to be resolved....

The figure seen through or imaged by an optical system. It may contain structures, natural or artificial, or it may be the real or virtual image of an object formed by another optical system. In...

In holography, the wave of light that illuminates the object to be recorded, which diffracts it to the recording medium, where it interferes with the reference beam, generating the hologram.

The movement of an object seen through a refracting prism toward the apex of a prism.

The distance between the object and the cornea, or the first surface of the objective in an optical device.

In an optical system, the space between the object being viewed and the system entrance pupil.

Distance between the front vertex of a lens and the object.

The optical element that receives light from the object and forms the first or primary image in telescopes and microscopes. In cameras, the image produced by the objective is the final image. In...

A coarse diffraction grating that is used to form a scale of intensities to determine the relative magnitudes of stars. The grating is placed over the objective of a telescope to form a diffraction...

1. A prism used in some instruments to bend light 90° before it enters the objective. 2. A dispersing prism located in front of an astronomical telescope objective to produce spectra of all...

The image error that results from astigmatism, coma, oblique spherical aberration, lateral color and distortion.

A common technique in microscopy, oblique illumination is one in which the object is illuminated by a light source that is at an oblique angle (on the side) to the optical axis. This technique is...

A hemispherical covering that is rotatable about a central axis. There is a slit opening along one side wide enough to allow a telescope to be directed at any vertical angle up to 90°.

An acid-resistant, lustrous volcanic glass, usually black or banded.

A device that completely or partially restricts the amount of light reaching the eye.

Refers to the characteristic hue of the ocean according to the presence and concentration of specific minerals or substances, such as chlorophyll. Atmospheric aberrations of color must be corrected...

In optics, an octave typically refers to a range of frequencies or wavelengths that spans a factor of 2. In other words, when dealing with optics, an octave encompasses a doubling of frequency or...

Ocular accommodation is the process by which the eye changes its optical power to maintain a clear image (focus) on an object as its distance varies. This process is essential for seeing objects at...

The eye's involuntary reaction in the process of accommodation. This reflex is most dramatic in response to looking at a distant object after having previously been focused on a near object or vice...

The prism used in a rangefinder to bend the lines of sight through the instruments into the eyepieces.

That surface of a lens located nearest to the eye.

An electro-optical infrared tracker consisting of a beamsplitter, an illuminating source, an image dissector tube and an electronics unit, that automatically acquires and tracks particular eye...

Off-axis paraboloid and ellipsoid mirrors are specialized optical components used in various optical systems, particularly in applications requiring precise focusing, collimation, or imaging of...

A prism or prism assembly that serves to displace the instrument's optical axis.

The electrical resistance between two points of a conductor when a constant difference of potential of one volt, applied between these points, produces in this conductor a current of one ampere, the...

A form of high-power microscope objective where the space between the object and the first element is filled with an oil having the same index as that element. This form reduces losses, increases the...

A polished plano-parallel plate that is contacted to an unpolished glass surface to permit see-through analysis of the material. The plate eliminates effects because of the surface quality of the...

Oleophobic is a term used to describe substances or materials that repel or resist oils. The word oleophobic comes from the Greek words "oleo," meaning oil, and "phobos," meaning fear. Oleophobic...

On-board optics refers to optical systems integrated into devices or platforms for various purposes, such as imaging, navigation, communication, and sensing. These systems are crucial in a wide range...

A glow discharge tube placed on an insulating rod to detect the presence of high-frequency radiation in the vicinity of a transmitter. The tube indicates the presence of the radiation by the glow...

An instrument for measuring opacity.

Opacity refers to the degree to which something is not transparent or translucent, meaning that it doesn't allow light to pass through it easily. It's a measure of how much a material obstructs the...

A material consisting of very small colorless particles imbedded in a clear glass matrix. It is available in two forms: flashed opal and pot opal. The flashed variety consists of a rather thin layer...

A tungsten filament lamp that uses an opal glass bulb to diffuse light.

A term describing a substance that is impervious to light; the characteristic of a substance that has no luminous transmittance.

An opaque projector is a device used for enlarging and projecting images from opaque objects such as printed pages, photographs, or three-dimensional objects onto a screen or surface. Unlike a...