Zeiss Axiolab A Especificaciones descargar pdf (Pagina 78)

OPERATION

Carl Zeiss Lighting and contrasting method in transmitted light Axio Lab.A1

78 430037-7144-001 04/2013

4.1.4 Setting transmitted light polarization

4.1.4.1 Detecting birefringence

(1) Application

The transmitted light polarization method is used for specimens which change the state of polarization of

light. These specimens, such as crystals, minerals or polymers, are referred to as birefringent. When these

birefringent substances are viewed between crossed polarizers (polarizer A analyzer), they appear bright

while their surroundings remain dark.

Birefringent substances are identified in that they show four bright and four dark positions when rotated

through 360° between crossed polarizers. Depending on birefringence, thickness and orientation of the

specimen, interference colors ranging from gray (mostly with biological specimens) to white, yellow, red

and blue appear in this process. These interference colors can be of the first or any higher order.

(2) Instrumentation

Polarization methods can be used in the transmitted light on Axio Lab.A1 microscopes for transmitted

light polarization and conoscopy.

 Tension-free objectives

 Rotary stage Pol

 Polarizer D (rotatable or fixed)

 Analyzer slide D, fixed, or lambda or lambda/4 compensator

 Depolarizer (for screwing into Axio Lab.A1 tubes) to avoid undesirable polarization effects

The depolarizer is already incorporated in the Axio Lb.A1 stand for conoscopy.

A depolarizer (quartz depolarizer) should be installed in all microscopes used for examining

mineral/geological specimens.

A depolarizer suppresses undesirable polarization effects which may occur after the analyzer (e.g. on

prism surfaces in the tube), or shifts these to higher orders.

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Zeiss Axiolab A Especificaciones Pagina 78