Photonics Dictionary: S

An aperture consisting of a semitransparent central region whose amplitude transmittance only is varied, and the relative phase difference between the central and annular region is fixed as p -...

Imaging radar that increases the sweep of its along-track (or azimuth) capacity by measuring not only the time delay of the echoes returning from the microwave pulse transmitted by its antenna (or...

Scalar diffraction theory is a simplified approach used to describe the propagation of electromagnetic waves, particularly light, as they encounter obstacles or apertures. It is termed "scalar"...

A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the mirror. The purpose of the plate is to correct the spherical aberration of the...

The Shack-Hartmann wavefront sensor is an optical device used for measuring the wavefront aberrations of an optical system. It is widely used in adaptive optics systems to correct distortions and...

An aperture, usually rectangular in shape, with a large length-to-width ratio, and a fixed or adjustable shape through which radiation enters or leaves an instrument. The aperture is generally small...

An instrument used for viewing in low levels of illumination by means of infrared radiation. A high-aperture lens forms an image of distant objects on the photocathode of an infrared-sensitive image...

A lens that exhibits spherical aberration when used at large aperture settings, and that forms an image with a slightly blurred outline.

A photographic objective that uses the thick meniscus principle to obtain its power. It is designed to photograph small fields at large apertures.

To reduce the size of a lens aperture, which increases the depth of field.

A lens system made up of two sets of similar lenses, each of which compensates for many of the aberrations produced by the other. The lens sets are arranged symmetrically on either side of the...