Photonics Dictionary: A

A visible laser beam generated coaxially with an infrared or other invisible laser beam to aid in its positioning.

An attenuator is an electronic or optical device used to reduce the power or intensity of a signal without significantly affecting its waveform or other characteristics. Attenuators are commonly used...

A doped or absorbing transparent medium cut or molded into a wedge in order to measure the real and imaginary components of the refractive index. An internally reflected Gaussian beam is interfered...

A hologram formed when the light of the illuminating beam is absorbed in correspondence with the recording exposure. In application, absorption holograms are intended for use in satellite...

The recorded interference pattern formed by the interference of two sound beams.

The optical reconstruction of image information contained in a sound field. First the diffraction pattern, formed by an object irradiated by ultrasonic rays, interferes with a mutually coherent...

The angular change of an incident beam due to vibrational induced refractive index changes within a crystal.

Light diffracted by a solid (usually quartz in crystal or fused form) traversed by acoustic waves. If the ultrasonic wavelength is larger than the diameter of the light beam, the diffraction orders...

A device that varies the amplitude and phase of a light beam; e.g., from a laser or by sound waves. Also known as a Bragg cell.

An acousto-optic modulator (AOM) is a device that utilizes the interaction between sound waves and light waves to modulate or control the intensity, frequency, phase, or direction of laser beams. It...

A bulk crystalline optic which permits the propagation of light through a volume of index altered material. The variation in refractive index along the material volume is due to a piezoelectric...

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

Additive manufacturing (AM), also known as 3D printing, is a manufacturing process that involves creating three-dimensional objects by adding material layer by layer. This is in contrast to...

Method for studying absorption coefficients of low-loss materials, in which a sample is allowed to come to thermal equilibrium with its surrounding blackened enclosure. The sample is irradiated with...

An accelerator at the Argonne National Laboratory, providing powerful x-ray beams for materials research applications.

An alexandrite laser is a solid-state laser that utilizes a synthetic crystal made from the rare earth element alexandrite (BeAl2O4:Cr3+). This crystal is capable of emitting laser light in the...

Left- and right-hand circularly polarized beams that are produced at different velocities by passing plane-polarized light through an optical substance. When recombined, they exhibit different phases...

Charged frozen pellets that are rapidly bombarded with a focused high-power laser to form a dense plasma that can be heated and sustained with neutral beams.

An analog method of moving a cathode-ray tube beam across a display screen face, commonly used in high-performance vector and character generators.

The angle through which a beam is deflected.

A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for...

A loss of resolution or detail in a television signal caused by the size of the electron scanning beam.

The reduction in luminance of a light beam due to absorption and scattering as it passes through the atmosphere.

Irregularities and disturbances in the atmosphere that are of particular interest because they induce random temporal and spatial phase and amplitude fluctuations that destroy the optical quality and...

Attenuated total reflectance (ATR) spectroscopy is a technique used in analytical chemistry to obtain IR spectra of samples. It is particularly useful for analyzing solid and liquid samples without...

A spectrograph in which the refracted beam returns almost along the path traveled by the incident beam, and is brought to a focus by the lens that collimates the incident beam.

An autocollimator is an optical instrument used for measuring small angular deviations with high precision. It operates on the principle of autocollimation, where a light source is directed onto a...

A microscope to which a beamsplitter and illuminated reticle have been added to measure the radius of curvature of a spherical surface by locating both surface and center and calculating the distance...

An axicon is a type of optical component characterized by its conical shape and its ability to transform a collimated Gaussian beam of light into a ring-shaped beam with a gradually increasing...