What is the optical limit of a microscope and why?

Not electron microscope.Why can't we simply produce more powerful lenses (larger/smaller?) or does it have something to do with photons-just always wondered,that's all. Also,have we reached a limit with images in an electron microscope?|||The optical limit of a microscope is defined by the wave property of light known as diffraction. The resolution of a lens is a function of its wavelength and numerical aperture. The numerical aperture is the sine of the semi angle of the cone from which light is either collected from an object or focused to an image. (They are equivalent.)





The smaller the wavelength the better the resolution. Electrons in an electron microscope have a much smaller wavelength than light. That is why an electron microscope has better resolution. Similarly using a blue laser instead of an infrared one (smaller wavelength) in a DVD player allows one to pack more information onto the DVD disk.





The larger the numerical aperture (cone of focused light) the larger the resolution. Hence a high numerical aperture microscope objective has better resolution than a low numerical aperture one.





One can magnify an image so that our eyes can see more detail than the optical system can resolve. This is called empty magnification because although the image gets larger it does not contain more information. It is a bit like over magnifying a digital picture until the pixels become very large.