Compensators, polarized light Senarmont

A standard polarized-light microscope equipped with a Senarmont compensator, having magniflca tions up to 400X, and a rotatable analyzer with a graduated scale are used by the writer. All the obser vations are made with the use of the upper element of the substage condensing lens on the microscope. 

Insert the Senarmont compensator, properly oriented so that the darkness of the background results in cross-polarized light. Place a green filter in the path of the incoming light. The green filter facilitates observation of the alite crystal compensation point determined in the next step. 

Polarized-light microscope Senarmont compensator Reflected-light (metallo-graphic) microscope Petrographic slides (46x24 mm)... 

That is, a linear polarized light with polarization vector forming an angle of ///2 with initial polarization vector. Hence, an analyser allows determination of ///2 after rotating to darkness as done when using a Senarmont compensator. 

A polarizing microscope for transmitted light usually has a polarizer at a fixed azimuth beneath the substage condenser, and an analyzer in the microscope tube above the objective. Typically, a compensator is inserted at 45° beneath the analyzer. Some compensators (such as the de Senarmont) are fixed in azimuth, and measurements are made with a rotary analyzer with a variable azimuth. For other compensators, the analyzer is fixed and the compensator is rotated or tilted to make measurements in the axis of the microscope. 

---