Conoscopic interference pattern: Difference between revisions

Revision as of 12:34, 26 July 2010

Revision as of 02:18, 10 September 2010

Line 1:

{{technicalTechnical|date=December 2009}}

:''This page is about the geology/optical mineralogy term. For general information about interference, see [[Interference (wave propagation)]] or [[Interference pattern]]s''.

A '''Conoscopic interference pattern''' or '''interference figure''' is the best way to determine if a [[mineral]] is uniaxial or biaxial and also for determining optic sign in [[optical mineralogy]]. The observed interference figure essentially shows all possible [[birefringence]] colors at once, including the extinctions (in dark bands called isogyres).

In [[optical mineralogy]] a [[petrographic microscope]] and cross-[[polarized light]] are often used to view the interference pattern. This is done by placing a [[Bertrand lens]] (Emile Bertrand, 1878) between a high-power microscope objective and the eyepiece. The microscope's condenser is brought up close underneath the specimen to produce a wide divergence of polarized rays through a small point. There are many other techniques used to observe the interference pattern.

A uniaxial mineral will show a typical 'Maltese' cross shape and its isogyres, which will revolve/orbit around a projection of the optical axis as the stage is rotated.

Line 14:

==References==

{{citeCite book

|author=W.D. Nesse

|year=1991

Line 23:

}}

{{citeCite book

|author=Albert Johannsen

|year=1914

Line 32:

}}

{{DEFAULTSORT:Conoscopic Interference Pattern}}

[[Category:Optical mineralogy]]

[[Category: petrologyPetrology]]

[[Category: geologyGeology]]

[[Category: opticsOptics]]