An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

An optical device, a modern version of the → Hartmann test, used for analyzing the wavefront of light. Theses sensors can be used to characterize the performance of optical systems. Moreover, they are increasingly used in real-time applications, such as → adaptive optics to remove the wavefront distortion before creating an image. It consists of a microlens array placed in front of a CCD array. A planar wavefront that is transmitted through a microlens array and imaged on the CCD array will form a regular pattern of bright spots. If, however, the wavefront is distorted, the light imaged on the CCD will consist of some regularly spaced spots mixed with displaced spots and missing spots. This information is used to calculate the shape of the wavefront that was incident on the microlens array.

Named after the German astronomer Johannes Hartmann (1865-1936), who first developed the method, and R. V. Shack, who in the late 1960s replaced the screen by a microlens array; → wavefront; → sensor.

The locus of adjacent points possessing the same phase in the path of a wave motion. Its surface is uniform (spherical or plane) and normal to propagation direction in an isotropic medium. → wavefront distortion.

→ wave; → front.

In → adaptive optics, eliminating the effects of atmospheric turbulence on the wavefront of the object being observed. → wavefront distortion.

→ wavefront; → correction.

The disruption of the spherical shape of a wavefront due to atmospheric turbulence which makes the adjacent points in the wavefront out of phase.

→ wavefront; → distortion.

In adaptive optics, a device that analyzes the light sample coming from the wavefront and determines the error in each part of the beam. The wavefront sensor used in adaptive optics is a → Shack-Hartmann type, which works in conjunction with a deformable mirror.

→ wavefront; → sensor.

The average slope in both the X and Y directions of a → wavefront or phase profile across the pupil of an optical system.

→ wavefront; → tilt.