* Astronomy

The 300 Year Evolution of the Maksutov-Cassegrain Telescope
In 1663 a Scottish mathematician named James Gregory designed the first reflecting telescope, envisioning a small secondary mirror that reflected light through a hole drilled in the main mirror. The design also called for two concave mirrors, with the secondary mirror placed beyond (outside) the focal point of the main mirror. Unfortunately, the technology of the mid-1600's could not manufacture precise enough mirrors to turn Gregory's design into a working instrument.

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The Maksutov or 'Mak' is a catadioptric telescope design that employs a full diameter positive meniscus lens (commonly called a "corrector plate") to correct the problems of off-axis aberrations such as coma found in reflecting telescopes while also correcting chromatic aberration. The design is most commonly seen in a Cassegrain variation, with an integrated secondary, that can use all-spherical elements, thereby simplifying fabrication.
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