Photonics Dictionary

Spatio-temporal optical coherence tomography (ST-OCT) is an advanced imaging technique that combines the principles of optical coherence tomography (OCT) with spatio-temporal modulation methods to...

A technique for obtaining improved resolution of images produced by large telescopes and distorted by the effects of atmospheric turbulence. Many individual exposures are recorded at high speeds by a...

Refers to the variety of techniques that use the interference pattern produced by laser light diffusely reflected by an object. There are two basic techniques: direct laser photography, used when...

Spectral domain optical coherence tomography is an imaging technique used in medical diagnostics, particularly in ophthalmology, to visualize and analyze the internal structures of biological...

A spectral signature, in the context of remote sensing and spectroscopy, refers to the unique pattern or characteristic spectral response of a material or object across different wavelengths of the...

Spectra can be conveniently recorded on photographic film or plates. The portions that are occupied by regions of the recorded developed images on the film or plate can be determined with some...

An optical instrument for forming the spectrum of a light source and recording it on a film. The dispersing medium may be a prism or a diffraction grating. A concave grating requires no other means...

The slits in a spectrograph that form images of spectral lines. Slits may be bilateral or unilateral, and generally close down to 0.01 mm and open up to almost a whole millimeter. The edges of the...

The image of the sun produced by a spectroheliograph.

An instrument in which an image of the sun is scanned by the entrance slit of a monochromator, the exit slit simultaneously scanning a photographic plate for analysis of the solar spectral lines. If...

An instrument similar to the spectroheliograph, but having a scanning method that is performed by a pair of rapidly oscillating slits or a rotating glass block located before a pair of fixed slits at...

A kind of spectrograph in which some form of detector, other than a photographic film, is used to measure the distribution of radiation in a particular wavelength region.

A reflector that exhibits specular reflectance, producing a direct image of its source. Also known as regular reflectance.

A spheric lens, also known as a spherical lens, is a type of optical lens with at least one surface that is part of a sphere. This means that the lens surface is curved in a symmetrical manner,...

Spherical aberration is an optical aberration that occurs when light rays passing through a lens or curved optical surface do not converge or diverge to a single focal point. Instead of focusing to a...

Potential alternative to the conventional pulse approximation method of digital image processing because of its highly desirable interpolating and approximating characteristics.

The field of view seen through some types of coincidence rangefinders. It is formed by the juxtaposition of opposite halves of the images produced by two objectives, the half-images being separated...

A close-up lens, semicircular in shape, that is mounted in front of a conventional lens focused at infinity. The result is an image made up of two sections; one focused through the split lens on near...

The interference of the two real images formed by a Billet split lens.

A method of evaluating image quality whereby a large number of rays are traced through a lens from a single object point, and their intersections with the focal plane are plotted and analyzed.

The distribution of energy about the image of a point source in the focal plane of an optical system.

A phenomenon that causes the details in an image to appear at a spatial frequency higher than that at which the contrast first drops to zero. A phase reversal will accompany this phenomenon, often...

The determination of distance based upon the known size of an object and the size of its image at the image plane of an optical system.

In infrared imaging systems used for mass screening of printed circuit boards or other quality control applications, an image of an ideal component that is stored in the system's memory and then...

The combination of two waves having the same frequency and amplitude and traveling in opposite directions. Standing waves are indicated by a stationary set of nodes spaced one-half wavelength apart...

The visual examination by a trained observer of the image of a point source. Any coloring or departure from the Airy disc rings indicates the presence of aberrations in the lens forming that image.

A projection printer that is capable of reproducing a multiplicity of images from a master transparency on a single support coated with a photosensitive layer by indexing the receiving material from...

The unit solid angle subtended at the center of a sphere by an area on its surface equivalent to the square of the radius; the unit of solid angular measurement, often used in problems of...

A camera with two taking lenses and synchronized shutters. Two images are recorded simultaneously on separate frames, producing a three-dimensional image when viewed through the proper apparatus.

A projector designed to give each of the observer's eyes its own disparate image.

A method of creating real three-dimensional models by using lasers driven by CAD software. In contrast to the normal practice of removing material, this process polymerizes a liquid to quickly...

Wide-field, low-magnification device that consists of two compound microscopes focused on a single object, producing an erect three-dimensional image.

The use of a specialized optical microscope designed to provide a more three-dimensional view of a sample. Stereomicroscopy usually uses reflected light and provides enhanced depth perception via the...

A small instrument containing a picture support and a pair of magnifying lenses so arranged that the left eye sees only the picture taken with the left lens of the stereo camera, and the right eye...

The photographing of a scene from positions corresponding to the locations of both eyes. A viewing device is used to present one picture to each eye for fusion of the retinal images, giving a...

A rangefinder similar to a pair of binoculars with a long base, a dot or other wander mark provided in each eyepiece field, together forming an apparent point in space. When one dot is moved...

A television system in which the images produced appear three-dimensional.

The array of methods used in the transmission and reception of pictures and images with a three-dimensional appearance.

The process of creating a large, panoramic image by aligning and joining a set of smaller images. Image processing is used to obscure the edges between the smaller images, producing a seamless...

Stochastic optical reconstruction microscopy (STORM) is a superresolution microscopy technique that enables imaging of biological specimens at resolutions beyond the diffraction limit of conventional...

A streak camera is a specialized instrument used to capture and analyze ultrafast phenomena, such as extremely short pulses of light or rapidly changing events. Unlike traditional cameras that...

The ratio of the illuminance at the peak of the diffraction pattern of an aberrated point image to that at the peak of an aberration-free image as formed by the same optical system.

Structured illumination microscopy (SIM) is an advanced optical imaging technique used in microscopy to enhance the resolution of images beyond the diffraction limit imposed by traditional light...

The pattern used as a probe in morphological image processing to manipulate the size and shape of objects in an image.

The distance between two focal lines in an astigmatic image produced by a lens or mirror.