| Revision as of 15:54, 2 June 2009 editDthomsen8 (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers498,600 edits Added a link to Bausch & Lomb and other instruments--~~~~← Previous edit |
Latest revision as of 01:05, 16 June 2017 edit undoTom.Reding (talk | contribs)Autopatrolled, Extended confirmed users, Page movers, Template editors3,879,345 editsm +{{Redirect category shell}} for multiple-{{R}} #Rs using AWB |
| (9 intermediate revisions by 6 users not shown) |
| Line 1: |
Line 1: |
|
|
#REDIRECT ] |
|
'''Vertometer''' was the trade name of an instrument made by ] (B&L) and later by ]. |
|
|
Lensometer was the trade name of the nearly similar instrument made by ]. |
|
|
Neither the Vertometer or the Lensometer is now being made. |
|
|
] is a generic name that can be applied to any lens measuring instrument. |
|
|
''''''A '''vertometer''' is an ophthalmic bench instrument used to measure ] of a lens. It differs from a ] or ] which is a general dispensary tool for ] to verify spectacle prescriptions at the laboratory. A vertometer, on the other hand, is a more precision instrument used to locate, mark, and index a lens optical center for edging, mounting, and construction of a ] ]. |
|
|
|
|
|
|
|
{{Redirect category shell|1= |
|
== History naming the precision instrument == |
|
|
|
{{R from merge}} |
|
The theory of geometrical optics uses ray tracing techniques. In many of his models, ] used a mathematical formula that measured a ] distance. This nomenclature prevailed throughout hundreds of years, during a time that studies of optics may have been misunderstood. Derived from the word, the measure of the focal length of a lens is represented by the reciprocal of the vertex distance in meters, or ]s. Vertometers measure ''sphere ± cylinder x axis'', and can be used to calculate prismatic power by indexing the optical center offset from the visual axis. An ink coated stylus is used to mark optic centers on the lens in the optical laboratory. A millimeter rule would be nearby for spectacle eyesize fittings. |
|
|
|
{{R from duplicated article}} |
|
|
|
|
|
}} |
|
== See also == |
|
|
* ] |
|
|
* ] |
|
|
|
|
|
== References == |
|
|
* ''(includes picture of instrument)'' |
|
|
|
|
|
] |
|
|
] |
|