What is Spectrograph?
[[File:Solar Spectrograph 2, Ondřejov Astronomical.jpg|thumb|A Horizontal Solar Spectrograph]] A '''spectrograph''' is an instrument that breaks up a [[wave (physics)|wave]] into a [[frequency spectrum]]. These could be sound, light or radio waves. For example the frequency spectrum of light is the brightness (intensity) and the amount of each colour. There are several kinds of machines called ''spectrographs'', used to look at different waves. The term was first used in 1884.<ref>[http://www.merriam-webster.com/dictionary/spectrograph Merriam-Webster Dictionary: Spectrograph]</ref> A spectrograph is closely related to a [[polychromator]]. ==Spectrographs and astronomy== In [[astronomy]], the first spectrographs used [[photographic paper]] as the detector. The star [[stellar classification|spectral classification]] and discovery of the [[main sequence]], [[Hubble's law]] and the [[Galaxy morphological classification|Hubble sequence]] were all made using photographic paper. The plant [[pigment]] [[phytochrome]] was discovered using a spectrograph that used living plants as the detector. New spectrographs use electronic detectors, such as [[Charge-coupled device|CCD]]s which can be used for both visible and [[ultraviolet|UV]] light. The type of detector depends on the wavelengths of light to be recorded. ==Echelle spectrograph== An [[echelle spectrograph]] is a special machine which is able to break up light waves, with a high resolution and little interference. It does this by using very narrow slits which breaks light into beams, and then breaking up those beams again. ==References== {{reflist}} * James, John (2007), ''Spectrograph Design Fundamentals'' (Cambridge University Press) {{ISBN|0521864631}} ==Other websites== *[http://outreach.atnf.csiro.au/education/senior/astrophysics/spectrographs.html Spectrograph for astronomical Spectra] {{Webarchive|url=https://web.archive.org/web/20130126044903/http://outreach.atnf.csiro.au/education/senior/astrophysics/spectrographs.html |date=2013-01-26 }} [[Category: