Reasonable alignment of the optical microscope's objective lens and eyepiece
When selecting objective lenses and eyepieces, there are two main considerations:
Category matching. That is, all plan objectives must be used in conjunction with special plan eyepieces.
Second, reasonable matching of magnification. Under a certain magnification, the objective lens and the 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 lens with a numerical aperture of 0.65 to observe the specimen, what size should you choose?
First, calculate the effective total multiple based on the effective magnification, and then divide by 40, which is the multiple of the eyepiece that should be selected. 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 in the range of effective magnification (500 to 1000 times). If the eyepiece magnification is too low and the total magnification is too small, the resolution of the objective lens cannot be fully utilized, and the details that can be recognized are crowded together and difficult to distinguish because the total magnification is too small. The magnification obtained by the eyepiece higher than 16 times is called "empty magnification", which does not improve the resolution of the affected details, but the clear depth is small, and the structure of different levels cannot be clearly reflected.
