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Thread: Why does a light microscope have such a low resolution?

  1. #1 Why does a light microscope have such a low resolution? 
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    I have already posted this in biology but feel it is probably more relevant to physics. I have always struggled immensely with understanding optics and how they work in standard light microscopy. I wonder if anyone here can help me.

    I believe it is the long wavelength of light that is responsible for the large diffraction patterns of structures being viewed through a light microscope (thus the reason for its low resolution). The wikipedia page on optical microscopes (http://en.wikipedia.org/wiki/Optical...pe#Limitations) also states that the refractive index of the objective lens material and the numerical aperture of the lens are further causes of low resolution. In regard to the refractive index of the lens, does this mean that a lens made of a material with a refractive index as that of a standard light microscope objective causes light to refract in a way that results in blurring which affects resolution (and is this blurring due to the individual wavelengths/colors of light bending at slightly different angles?)? Is this problem something that just unavoidably occurs when light is made to pass through glass and is something that cannot be improved upon because glass is the only lens material that can be used in the design of a light microscope? Is the only way that resolution could then be slightly improved with the existing lens of glass material is to use light of a shorter wavelength such as ultraviolet? How does the numerical aperture affect the microscope resolution? Is there anything that can be done at all to alter the numerical aperture of the lens and refractive index of the objective lens to improve resolution?

    Sorry if I have made some mistakes! I'd really appreciate any help you can offer.

    Thank you


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  3. #2  
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    Regarding the refractive index, I think you are referring to chromatic aberration. Regarding the aperture, I think you are referring to spherical aberration. This article discusses various kinds of aberration.

    http://en.wikipedia.org/wiki/Aberrat...ptical_systems

    Oops, I should have read the first article. They weren't referring to the aberration.


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