Solar Eyepiece

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Solar Eyepiece


an eyepiece for a telescope designed for visual observation of the sun. A solar eyepiece is used to provide a reduction in the brightness of the sun’s image with minimum loss of the telescope’s resolving power. By contrast, when the lens or mirror that produces the image is stopped down with a diaphragm for this purpose, the resolving power of the telescope is diminished. Devices used in solar eyepieces to attenuate the light include neutral filters, photometer wedges, and polarizing devices.

Figure 1. Solar eyepiece: (a) general view, (b) schematic

In the most common type of solar eyepiece, the light is reflected from the plane mirror or wedge M (see Figure 1) and then passes through a two-component prism. The prism Pj is made of crown glass, and the prism P2 is a liquid prism filled with liquid petrolatum. Since the refractive indexes of the materials of which the prisms are made are very close in value, only a small portion of the light is reflected from the interface. This light then passes through the ordinary ocular O.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Four months later she came across a box marked "Christmas decorations." It proved to contain seven eyepieces for powers from 75x to 450x, a star diagonal, a Sun diagonal (also called a Herschel wedge), a solar eyepiece filter, and an eyepiece box.