Photonics Dictionary: O

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...

coma, fifth order aberration with on-axis focal point variation with incident off axis ray height position

The physical adaption of the eye lens, by means of ciliary muscle contraction, in order to maintain a clear, in focus image of light and other objects and surroundings at a given distance onto the...

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...

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...

Also referred to as the opposition surge, the opposition effect is a photometric phenomenon in which a rough retroreflective surface appears brighter when illuminated from directly behind the...

Optical character recognition (OCR) is a technology that is used to convert printed or handwritten text into machine-readable text. OCR software and systems are designed to recognize and extract...

The transmission and reception of information by optical devices and sensors.

The procedure by which the similarity of an optical signal or waveform to a reference-stored signal or waveform is determined. Generally the reference is stored as a matched filter.

In dry etching, a method of characterizing the composition of solid materials such as metal. Atoms in the OES technique are excited by energy that comes from a spark formed between the sample and an...

The use of photonic devices rather than electronic devices to make connections within and between integrated circuits.

Optical phase distortion refers to a phenomenon where the phase of an optical wavefront is altered as it propagates through a medium. This distortion can result from variations in the refractive...

A measure of image quality produced by an optical system. May be specified in terms of cycles per millimeter, referencing a repeating bar pattern; or angular resolution, referencing the angle...

1. The angular displacement of the plane of polarization of light passing through a medium. 2. The azimuthal displacement of the field of view achieved with a rotating prism.

The function that characterizes the quality of an optical system by denoting the modulation and spatial phase shift of the image of a sinusoidal object with frequency as the independent variable.

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...

The process by which an atomic system changes from one energy level to another by either the emission or absorption of visible, infrared or ultraviolet radiation.

A configuration or device mounted at the end of a fiber or cable that is intended to prevent reflection.

An optogenetic technique that embeds genetically-engineered proteins to the heart to aid in terminating arrhythmias. After the proteins are embedded in the heart, it can be defibrillated by pulses of...

Optimization method used in optical design computer programs that employs a variable-by-variable approach to construct new variables that are orthogonal. This technique can uncover solutions that...

Point at which a laser's material gain is equal to, or greater than, the circuit losses.

A process for the production of optical fibers. A glass bait is rotated in a traversing flame of a reaction burner. Reactants passed through the flame react with oxygen at the high temperatures to...

A hologram facet illumination technique in which the illuminating beam is twice the size of the hologram facet so that full hologram resolution capability can be realized and scanning dead time is...

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...

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...

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

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...

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.