Photonics Dictionary: D

Dense wavelength division multiplexing (DWDM) is an optical communication technique used to increase the data-carrying capacity of optical fiber networks by simultaneously transmitting multiple...

A small handheld instrument consisting of a slit and collimator that feeds light into a small direct-vision dispersing prism. The eye is placed behind the prism to observe the spectrum of a colored...

An assembly of multiple prisms that disperses incident light into its spectral components without deviating light at the central wavelength.

The near-point distance of the normal eye. The value of 10 in. or 25 cm is normal. This value is used in evaluating the designated magnification of a simple magnifier or eyepiece.

A defect of a binocular instrument causing two images to be seen separately instead of being fused. It is caused when the optical axes of the two telescopes are not parallel. In minor cases, the eyes...

Deep learning is a subset of machine learning that involves the use of artificial neural networks to model and solve complex problems. The term "deep" in deep learning refers to the use of deep...

1. An optical device used for projection of enlarged images of transparencies or lantern slides on a screen. 2. A device designed to hold and backlight transparencies so that their images can be...

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...

A defect of vision where a single object appears as two. Also known as double vision.

A scanning technique in which the object is illuminated the entire time, and in which picture elements of the object are viewed singly by the television camera.

The observation of a reproduced television picture on the face of a cathode-ray tube.

The degree to which a vision system is capable of sensing differences in light intensity between two regions.

A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...

A fast, wide-angle lens used in television and photographic cameras, with excellent overall correction, but subject to residual oblique spherical aberration.