Photonics Dictionary: H

A direct-vision prism made in one piece that can be used only in parallel light.

A term used to describe a photograph, film or television picture where the values for black and white areas are at or near their limits, thereby giving the maximum degree of difference between them.

Distortion of the high frequencies of a signal. In television, the term generally applies to frequencies above the 15.7 kHz line frequency.

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

In television, the period during which the electron beam is cut off while the raster returns from the right-hand side of the screen to the left.

A device that controls the output of a television receiver's horizontal oscillator.

In television, the number of individual pixels that can be distinguished in a horizontal scanning line; also called horizontal definition.

The locus of the points in the field of binocular vision that are observed singly. The images of these points correspond to the respective retinal points.

A vision defect commonly referred to as farsightedness. Results when the image of a distant object is focused beyond the retina by the relaxed eye. The condition can be corrected by introducing a...