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 LENS ANALYSER RETARDATION PLATE (COMPENSATOR) GRADUATED CIRCULAR ROTATING STAGE LIGHT SOURCE POLARISER

FUNCTION EYEPIECE BERTRAND LENS 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.

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 POLARIZER confines white light to vibrate in one plane when light passes through it . The birefringent specimen breaks the polarized light into two components viz. ordinary and extra ordinary light. 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. 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 Low relief High relief Polarized light

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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