Physics:Stokes lens
| Stokes lens | |
|---|---|
| Medical diagnostics | |
| Synonyms | Stokes' lens |
| Test of | Astigmatism |
Stokes lens also known as variable power cross cylinder lens[1] is a lens used to diagnose a type of refractive error known as astigmatism.
Lens design
The Stokes lens also known as variable power cross cylinder lens, in its standard version, is a lens combination consisted of equal but opposite (one plano-convex and other plano-concave) power cylindrical lenses attached together in a way so that the lenses be rotated in opposite directions.[2][3] When the axes are parallel, the two powers cancel each other out to achieve the resulting power zero; When the axes are vertical, a sphero-cylindrical lens with maximum power is obtained.[3]
Uses
Stokes lens is a lens used to diagnose and measure astigmatism.[4][5]
Adaptations
American ophthalmologist Edward Jackson revised the Stokes lens concept and made a cross cylinder lens to refine power and axis of astigmatism.[2] This lens combination is known as Jackson cross cylinder.[2] Based on the Stokes lens, James P. Foley and Charles E. Campbell made a variable power astigmatic lens which is combination of two identical cylindrical powers instead of equal and opposite powers.[2][6]
History
In 1837, English mathematician and astronomer George Biddell Airy invented the cylindric lens and used it to correct astigmatism.[3] Irish English physicist and mathematician George Stokes invented Stokes lens in 1849.[3]
References
- ↑ Ferrer-Altabás, Sara; Micó, Vicente (10 April 2020). "Characterization of a compact low-cost Stokes lens for astigmatism compensation in optical instruments" (in EN). Applied Optics 59 (11): 3347–3352. doi:10.1364/AO.386247. ISSN 2155-3165. PMID 32400444. Bibcode: 2020ApOpt..59.3347F. https://opg.optica.org/ao/abstract.cfm?uri=ao-59-11-3347.
- ↑ 2.0 2.1 2.2 2.3 Ferrer-Altabás, Sara; Thibos, Larry; Micó, Vicente (14 March 2022). "Astigmatic Stokes lens revisited" (in EN). Optics Express 30 (6): 8974–8990. doi:10.1364/OE.450062. ISSN 1094-4087. PMID 35299337. Bibcode: 2022OExpr..30.8974F. https://opg.optica.org/oe/fulltext.cfm?uri=oe-30-6-8974&id=470070.
- ↑ 3.0 3.1 3.2 3.3 Wunsh, Stuart E. (10 July 2016). "The Cross Cylinder". https://entokey.com/the-cross-cylinder/.
- ↑ "Stokes lens". https://medical-dictionary.thefreedictionary.com/Stokes+lens#:~:text=(st%C5%8Dks),device%20used%20to%20diagnose%20astigmatism..
- ↑ Dennett, WS (1885). "The Stokes' Lens for Measuring Astigmatism.". Transactions of the American Ophthalmological Society 4: 106–10. PMID 25258975.
- ↑ Foley, James; Campbell, Charles (1999-10-01). "An Optical Device with Variable Astigmatic Power". Optometry and Vision Science 76 (9): 664–7. doi:10.1097/00006324-199909000-00025. PMID 10498009. https://www.researchgate.net/publication/12802369.
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