User talk:Swarup.mukhopadhyay

Principle of Metallurgical Microscope

A horizontal beam of light from some appropriate light source is diverted by means of a plane glass reflector or a Prism, downward and through the Microscope of the objective on the specific surface. A certain amount of incident light will be reflected fro the specimen surfaces and then reflected light finally which again passes through the objective Lens will form an enlarged image of the illuminated area. The main three parts of an Optical Microscope are -- 1.Objective Lens 2.Eye Piece Lens 3.Illuminating Sources.

The Metallurgical Microscope defers from the Biological type Microscope is that the specimen in Metallurgical Microscope is illuminated be some light source from top, as visible radiation is not able to propagate through a Metallography specimen. In Biological type light passes through the specimen from bottom portion.

Magnifying Power:- When objective and Eye-piece lens are at a distance of 250mm,the total magnification is equal to the product of the initial magnification of two optical systems. Initial magnifying power of an eyepiece & objective lens are M1 and M2 ,then M1 x  M2 is the Magnifying power. In case of Photo – Micrography or in cases where the image is projected by the Eye piece on to a screen then Magnifying power = DM1M2/250,Where D = Projected distance in mm from eyepiece to focusing screen.

Without knowing the initial magnification we can determine the total magnifying power of a Microscope by using a Stage – Micrometer. This is a flat-metal or glass plate which is accurately engraved with lines spaces 0.01mm,apart over a distance of about 1.0mm.This stage micrometer used as the object and the image of this lines are projected on to the focusing screen. The distance between the lines are measured and by simple calculation the exact magnifying power can be determined.--Swarup.mukhopadhyay (talk) 15:50, 11 May 2008 (UTC)