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A copyscope is type of refracting telescope that can be made by hand rather than bought in which the objective lens comes from an old photocopy machine, hence the origin of the name. [1] The lenses usually come from defective or old photocopiers, allowing for the objective to be obtained for free or at a low cost.
Ever since Galileo Galilei adapted a Dutch invention for astronomical use, astronomical telescope making has been an evolving discipline. Many astronomers after the time of Galileo built their own telescopes out of necessity, but the advent of amateurs in the field building telescopes for their own enjoyment and education seems to have come into prominence in the 20th century.
The force of gravity (red), the buoyancy force (green), and the resultant centripetal force (blue) In the following discussion, represents the acceleration due to gravity, represents the angular speed of the liquid's rotation, in radians per second, is the mass of an infinitesimal parcel of liquid material on the surface of the liquid, is the distance of the parcel from the axis of rotation ...
Adaptive thin shell mirror. [5]Adaptive optics was first envisioned by Horace W. Babcock in 1953, [6] [7] and was also considered in science fiction, as in Poul Anderson's novel Tau Zero (1970), but it did not come into common usage until advances in computer technology during the 1990s made the technique practical.
A Schmidt corrector plate is an aspheric lens which corrects the spherical aberration introduced by the spherical primary mirror of the Schmidt or Schmidt–Cassegrain telescope designs. It was invented by Bernhard Schmidt in 1931, [ 6 ] although it may have been independently invented by Finnish astronomer Yrjö Väisälä in 1924 (sometimes ...
[4] [5] [6] The array is designed to accommodate the addition of lenses to increase its effective aperture with each additional lens. [3] With 48 lenses, the instrument has a light gathering power equivalent to a 400 mm f /0.4 lens, or a refracting telescope with an objective lens diameter of 990 mm (39 in). In March 2021 plans were announced ...
A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel array as primary optics instead of a typical lens. It focuses light with a thin opaque foil sheet punched with specially shaped holes, thus focusing light on a certain point by using the phenomenon of diffraction.
Optical instruments like microscopes, telescopes, and DSLRs all have optical trains that guide the incoming light towards a detector or the eye of an observer. The optical train of a telescope is commonly called an optical tube assembly ( OTA ) or simply an optical tube .