Cheshire eyepiece

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A Cheshire eyepiece is an aid for aligning the optical axes of the mirrors or lenses in a telescope . The collimation of the optical elements of a telescope can be checked with a Cheshire eyepiece .

Layout and function

Cheshire eyepiece with the reticle (top left) at one end and the viewer (bottom right) at the other end

A Cheshire eyepiece, which itself does not contain any mirrors or lenses, can be used both on refractors and reflectors such as a Newtonian telescope or catadioptric devices such as a Maksutov-Newtonian telescope . To do this, it is inserted into the focuser instead of an optical eyepiece . A bright surface placed in the eyepiece at an angle of 45 degrees directs light into the eyepiece and thus into the telescope through a side opening.

Due to the beam path of the light through the mirrors or lenses of the telescope a corresponding image that can be viewed through a viewing opening at the rear end of the Cheshire eyepiece is formed. The shape and location of various elements of the image, including a crosshair on most modern Cheshire eyepieces, allow an assessment of optical collimation. Any errors or deviations found can usually be corrected by adjusting the telescope.

The design of the Cheshire eyepiece goes back to the English physicist Frederick James Cheshire , who published a corresponding article in the journal "Transactions of the Optical Society" in 1921 .

literature

  • Collimation and Adjustment Techniques. In: Maury Barlow Pepin: Care of Astronomical Telescopes and Accessories. A Manual for the Astronomical Observer and Amateur Telescope Maker. Springer, London and New York 2005, ISBN 978-1-8462-8071-9 , pp. 158-178

Individual evidence

  1. ^ Testing Your Refractor. In: Neil English: Choosing and Using a Refracting Telescope. Springer, London and New York 2011, ISBN 978-1-4419-6402-1 , pp. 221-232
  2. ^ Adjusting, Maintaining, and Testing Your Dob. In: Neil English: Choosing and Using a Dobsonian Telescope. Springer, London and New York 2011, ISBN 978-1-4419-8785-3 , pp. 191-200
  3. ^ Care and Feeding of a CAT. In: Rod Mollise: Choosing and Using a New CAT. Getting the Most from Your Schmidt Cassegrain or Any Catadioptric Telescope. Springer, London and New York 2009, ISBN 978-0-3870-9772-5 , pp. 223-235
  4. ^ Frederick James Cheshire: Note on an Eyepiece for Testing the Squaring-on of Telescope Object Glasses. In: Transactions of the Optical Society. 22/1921. Pp. 235/236

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