POWERPOINT PRESENTATION ON POLARISED MICROSCOPE

POLARISED LIGHT MICROSCOPE

Designed to observe optically anisotropic specimen (BIREFRINGENCE SPECIMEN)

Equipped with POLARISER and ANALYZER

Works on the principle of INTERFERENCE

COMPONENTS OF POLARISED LIGHT MICROSCOPE AND THEIR FUNCTION

EYEPIECE OBSERVATION TUBE BERTRAND LENSANALYSER RETARDATION PLATE (COMPENSATOR)GRADUATED CIRCULAR ROTATING STAGELIGHT SOURCEPOLARISER

COMPONENTS

EYEPIECE Eyepieces are fitted with a cross wire reticle to mark the center of the field of

view.

Orientation of the eyepiece with respect to the polarizer and analyzer is guaranteed by a point that slides into the observation tube sleeve

BERTRAND LENS

It is a specialized lens mounted within the observation tube.

Projects an interference pattern formed at objective rear focal plane in focus at the microscope image plane.

Is designed to allow accurate adjustment of the illuminating aperture diaphragm and to see interference figures.

FUNCTION

RETARDATION PLATE (COMPENSATOR)

These are inserted between the cross polarizers.

Enhances the optical path difference in the specimen.

GRADUATED CIRCULAR ROTATING STAGE

It is a 360 degree rotating specimen stage.

Facilitates the orientation studies with centration of the objective and stage with microscope optical axis.

It contains the Vernier scale to measure the degree of rotation of the specimen with accuracy of 0.1 degree.

FUNCTION OF MAJOR COMPONENTS

BIREFRINGENT SPECIMEN

Birefringence is an optical property of a material having a refractive index that depends on the polarization and propagation direction of light.

Birefringent materials have different indices of

refraction for light polarized parallel or perpendicular to the optical axis.

Two beams with orthogonal polarization are produced if illumination is at an angle to optical axis

Depending upon the orientation of the specimen, colour of the image changes

POLARIZER AND ANALYZER

I. POLARIZER confines white light to vibrate in one plane when light passes through it .

II. The birefringent specimen breaks the polarized light into two components viz. ordinary and extra ordinary light.

III.These two components of light when passes through ANALYZER, INTERFERENCE occurs by virtue of which image obtained is colourful .

DIFFERENCE BETWEEN SIMPLE MICROSCOPE AND POLARISED LIGHT MICROSCOPE

SIMPLE LIGHT MICROSCOPE

It has polarizer and analyzer.

An optically anisotropic specimen called birefringent specimen is used.

Works on the principle of interference.

Colourful image is obtained due to interference.

POLARISED LIGHT MICROSCOPE

It does not have these two components.

Any specimen can be used.

Works on the principle of reflection and refraction.

Color of the image obtained is same as that of the specimen.

Plane light

Polarized light

High relief

Low relief

FACTORS AFFECTING THE COLOR OF IMAGE

Orientation of the specimen.

Thickness of the specimen.

Path difference between the ordinary and extra ordinary light rays.

Orientation of the polarizer and analyzer with respect to each other.

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