Axiolab A Carl ZeissB 40-015 e 06/99 3-7(2) Transmitted-Light Polarization - Detection of BirefringenceThis technique is used for the examination of transparent, birefringent objects. Birefringence can berecognized, with crossed polarizer and analyzer, by the otherwise dark field of view being brightened 4times when the specimen stage is rotated about 360°. Respective of birefringence, thickness andorientation of the object, the interference colors range from just visible gray (e.g. in biological objects) towhite, yellow, red, blue, etc. and high-order white.• Set the microscope as usual for brightfieldexaminations in transmitted light.• Push in the plane glass pushrod (3-5/3).• Swing in polarizer (3-5/6) and set it to 0°.• Push in analyzer (3-5/1) until stop so that thefield of view is dark. When a ± 5° rotary analyzer is used,the analyzer must be in the centerstop position.• Move the object into the field of view and turnthe stage (3-5/4) containing the object. Birefringence is indicated by the eithercolorless or colored brightening of theobject. However, optically anisotropicmaterials can also remain dark if anisotropic direction, e.g. of opticallyuniaxial or biaxial crystals is orientedparallel to the observation direction.The conoscopic viewing methodmakes it possible to find out whetherthe object is isotropic or anisotropic.Fig. 3-5 Setting of transmitted-lightpolarization
