Photonics Dictionary

Developed for use in military reconnaissance systems, it consists of a polygonal mirror, drive motor, interface between motor and mirror, and control electronics. Also used in broadband video...

A method of polishing an aspheric surface by mechanically distorting the optic while polishing the surface to a perfect sphere. When the stress is released, the substrate assumes the desired aspheric...

An image of an object that appears above the object's true position as the result of abnormal refraction of the image rays by the atmosphere.

Also known as corner-cube reflector or retrodirective reflector. Three reflecting surfaces, perpendicular to each other, that are arranged like the inside corner of a cube. As the triple mirror has a...

A two-sided mirror suspended by a pendulum mechanism. An autocollimator set normal to such a mirror surface will, by definition, have its optical axis set horizontal.

A beamsplitting mirror that reflects as a function of wavelength.

A mirror that supplies equal reflectance for both the S-polarization and the P-polarization of a laser for a defined angle of incidence, usually 45°.

A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively transmit or reflect certain wavelengths of light while simultaneously absorbing...

An approximated measure of the smallest change in color temperature detectable by the human eye, defined as the reciprocal of the color temperature times 106. Also called mired or reciprocal...

MicroRNAs (miRNAs) are a class of small, single-stranded RNA molecules, typically consisting of about 19 to 24 nucleotides, that play important roles in the regulation of gene expression in cells....

A mid-infrared camera is a type of imaging device designed to capture images in the mid-infrared (mid-IR) spectral range, typically spanning wavelengths from approximately 3 to 12 µm. This...

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...

A cylindrical convex viewing mirror used for viewing distorted pictures formed by photographing the reflections of the objects in a similar type of mirror.

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

Aplanatic points refer to specific points in an optical system where certain aberrations, such as spherical aberration or coma, are minimized or eliminated. In an optical system, aberrations are...

An optical system having one or more lens or mirror components that have nonspherical surfaces. These surfaces, whether reflecting or refracting, serve to advance or retard the incident wavefront,...

An astronomical telescope is a type of optical instrument designed to gather and magnify light from distant celestial objects for observation and analysis. It typically consists of two main optical...

Technique of projecting an illuminated target at infinity and receiving the target image after reflection from a flat mirror surface.

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 two-mirror corrector for a parabolic primary mirror that provides anastigmatic performance for large astronomical telescopes.

A mirror used to manipulate the beam in a laser system.

A set of mirrors mounted on solenoids to move them into and out of the path of a laser beam, making it possible for multiple workstations to alternate using the single laser source.

A device for the internal inspection of hard-to-get-at mechanical parts, such as rifle barrels, sewer pipes, oil wells, or gas mains. The long narrow tube used contains a telescope system with as...

A portable instrument that uses a four-sided reflecting prism or set of mirrors to create a duplicate image of an object on a horizontal sheet, on which outlines of the subject may be traced by hand.

A two-mirror lens design used in astronomical telescopes, the primary being a parabola, the secondary a smaller hyperbola. The image formed is free of spherical aberration and color and is located...

A system that uses both reflection and refraction to achieve its focal power. While the relative powers of the lenses and mirrors vary from system to system, the use of the reflective surfaces to...

An optical system in which the only image-forming elements are curved-surface mirrors; e.g., a Cassegrain lens system.

In a laser, the optical resonator formed by two coaxial mirrors, one totally and one partially reflective, positioned so that laser oscillations occur.

The center of the sphere of which the surface of a lens or mirror forms a portion. Each curved surface of a lens has a center of curvature; the surfaces may be convex or concave.

1. Mounting a lens or mirror so that its optical axis is coincident with the optical or mechanical axes of other portions of the system. 2. The machining (edging) of the outside diameter of a lens...

In a reflecting telescope, the obstruction of the primary mirror by a secondary mirror which blocks a small amount of the light reflected by the primary mirror and introduces additional diffraction.

Description of a particle that cannot be superimposed on its mirror image.

Chirality is a property of certain molecules and objects in which they are non-superimposable on their mirror images. In other words, a chiral object or molecule cannot be exactly superimposed onto...

Circular dichroism (CD) is a spectroscopic technique used to study the structural characteristics of chiral (asymmetric) molecules, particularly biomolecules like proteins, nucleic acids, and certain...

A plane mirror mounted on a polar axis that lies parallel to the plane of the mirror. When the mirror is rotated once in 48 hours, celestial objects can be made to appear stationary and are...

An optical instrument used to determine the distance to a target being viewed. Two similar optical systems view the target via 45° mirrors at the ends of a fixed baseline. One system creates the...

An optical instrument consisting of a well- corrected objective lens or mirror with a light source and or object/image (i.e. illuminated slit or retical) at its focal plane. Collimators are used to...

A filter that serves to alter the color temperature and the mired value of the radiation emitted by a source.

A semitransparent mirror in an optical system that combines two or more output beams into a single coaxial beam.

A computer-generated hologram (CGH) is a holographic image produced using computational methods and algorithms, rather than traditional optical techniques. CGHs are generated entirely in digital form...

Concave is an adjective used to describe a surface or shape that curves inward or has a hollow or recessed appearance. In the context of geometry or optics, a concave shape is one that curves or...

A confocal resonator, also known as a confocal cavity or confocal laser resonator, is a type of optical resonator configuration used in laser systems. The term confocal in this context refers to the...

An interferometer formed by two similar concave spherical mirrors arranged with the center of one sphere on the other mirror. In this instrument the field is more concentrated by the axis of the...

The two points on the principal axis of a mirror or lens so positioned that light emitted from either point will be focused at the other, i.e., object and image points.