Reasonable collocation of objective lens and eyepiece of optical microscope
When choosing objective lenses and eyepieces, there are two main issues to consider:
*, a match on category. That is, all flat field objectives must be used in conjunction with special flat field eyepieces.
Second, reasonable matching of magnification. Under a certain magnification, the objective lens and eyepiece can be combined arbitrarily, but the premise of the combination is mainly to consider the effective magnification, which is an important rule for the correct use of the microscope. The effective magnification of the microscope is 500 to 1000 times the numerical aperture of the objective lens used, that is, the product of the magnification of the objective lens and the eyepiece is equal to 500 to 1000 times the numerical aperture of the objective lens.
If you use a 40X objective with a numerical aperture of 0.65 to observe the specimen, what size should you choose?
First, according to the effective magnification, the effective total multiple is obtained, and then divided by 40, that is, the multiple that should be selected for the eyepiece. The calculation process is: (0.65×500～0.65×1000)÷40≈8～16. That is to say: an objective lens with a numerical aperture of 0.65 should be matched with an eyepiece of 8 to 16 times within the range of effective magnification (500 to 1000 times). If the eyepiece magnification is too low, the total magnification is too small, the resolution of the objective lens cannot be fully utilized, and the details that could have been identified, because the total magnification is too small, are crowded together and difficult to distinguish. The magnification obtained by eyepieces higher than 16 times is called "empty magnification", which does not improve the resolution of affected details at all, but the clear depth is small and cannot clearly reflect the structure of different levels.
