Reasonable Matching of Objective Lens and Eyepiece of Optical Microscope
Reasonable combination of objective lens and eyepiece of optical microscope
When selecting objectives and eyepieces, there are two main considerations:
Firstly, matching in categories. All flat field objectives must be used in conjunction with specially designed flat field eyepieces.
Secondly, reasonable matching of magnification factors. At a certain magnification, the objective lens and eyepiece can be combined arbitrarily, but the premise of their combination is mainly to consider the effective magnification, which is an important rule for the correct use of microscopes. The effective magnification of a microscope is 500-1000 times the numerical aperture of the objective lens used, that is, the product of the magnification of the objective lens and eyepiece is equal to 500-1000 times the numerical aperture of the objective lens.
If you use a 40X objective lens with a numerical aperture of 0.65 to observe a specimen, what size should you choose? First, calculate the effective total magnification based on the effective magnification, and then divide it by 40 to obtain the magnification of 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 8-16x within the effective magnification range of 500-1000x. If the eyepiece magnification is too low and the total magnification is too small, the resolution of the objective lens cannot be fully utilized. Details that could have been recognized are difficult to distinguish when squeezed together due to the small total magnification. The magnification obtained by eyepieces with a magnification higher than 16 times is called "empty magnification", which does not improve the resolution of details, but instead has a smaller depth and cannot clearly reflect the structure of different levels.
