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Against-the-rule astigmatism – the horizontal meridian is steepest (a rugby ball or American football standing on its end). [17] Oblique astigmatism – the steepest curve lies in between 120 and 150 degrees and 30 and 60 degrees. [17] Irregular astigmatism – principal meridians are not perpendicular.
Developed by Australian ophthalmologist Noel Alpins and introduced in 1993, the Alpins Method provides a coherent basis for reporting astigmatism results, and on this basis became the standard in the major ophthalmology journals, [9] [10] [11] and was accepted worldwide for studies that include refraction and corneal astigmatism measurements.
Plucker is a free and open-source mobile and desktop e-book reader application with its own associated file format and software to automatically generate Plucker files from text, PDF, HTML, or other document format files, web sites or RSS feeds. The format is public and well-documented.
Interactive Forms is a mechanism to add forms to the PDF file format. PDF currently supports two different methods for integrating data and PDF forms. Both formats today coexist in the PDF specification: [38] [53] [54] [55] AcroForms (also known as Acrobat forms), introduced in the PDF 1.2 format specification and included in all later PDF ...
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For early electron microscopes - between the 1940s and 1960s [1] - astigmatism was one of the main performance limiting factors. [2] Sources of this astigmatism include misaligned objectives, non-uniform magnetic fields of the lenses, which was especially hard to correct, lenses that aren't perfectly circular and contamination on the objective ...
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.
For Dummies book on the subject; and For Dummies Quick Reference, which is a condensed alphabetical reference to the subject. A larger All-in-One Desk Reference format offers more comprehensive coverage of the subject, normally running about 750 pages. Also, some books in the series are smaller and do not follow the same formatting style as the ...