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The purpose of the microscope is to aim at reference marks with much higher accuracy than is possible using the naked eye. It is used in laboratories to measure the refractive index of flat specimens using the geometrical concepts of ray optics (Duc de Chaulnes’ method). [2]
Since the refractive index is a fundamental physical property of a substance, it is often used to identify a particular substance, confirm its purity, or measure its concentration. The refractive index is used to measure solids, liquids, and gases. Most commonly it is used to measure the concentration of a solute in an aqueous solution.
Information regarding the refractive index of a mineral can be observed by making comparisons with the surrounding materials. This could be other minerals or the medium in which a grain is mounted. The greater the difference in Optical relief the greater the difference in refractive index between the media. The material with a lower refractive ...
The volume of an object can thus be determined when the difference in refractive index between the object and the surrounding media is known. The success of the phase-contrast microscope has led to a number of subsequent phase-imaging methods.
The Becke line test is a technique in optical mineralogy that helps determine the relative refractive index of two materials. It is done by lowering the stage (increasing the focal distance) of the petrographic microscope and observing which direction the light appears to move. This movement will always go into the material of higher refractive ...
The index of refraction (n) is calculated from the change of angle of a collimated monochromatic beam of light from vacuum into liquid using Snell's law for refraction. Using the theory of light as an electromagnetic wave, [ 9 ] light takes a straight-line path through water at reduced speed ( v ) and wavelength ( λ ).
When the conditions for dispersion staining are met (the particle is mounted in a liquid with a matching refractive index in the visible range of wavelengths but with a very different refractive index) then the particle has a high refractive index in the red part of the spectrum and a lower refractive index in the blue.
The refractive index is normally smaller than 1 with a difference from 1 between 10 −7 and 10 −6. [citation needed] All of these methods produce images that can be used to calculate the projections (integrals) of the refractive index in the imaging direction.