CaF2-free medium flat-field apochromatic metallographic microobjective

Abstract

The invention discloses a CaF2-free medium flat-field apochromatic metallographic microobjective, consisting of special optical glass convex lenses without a CaF2 material and concave lenses, wherein the number of the convex lenses and concave lenses is six in total; and all the lenses are coaxial with the center of an object surface, and the sequence of all the lenses and the object surface from right to left is as follows: the object surface, the first convex lens, the second concave lens, the third convex lens, the fourth convex lens, the fifth concave lens and the sixth convex lens. The imaging is at infinity. In the invention, the long working distance W.D is more than 10mm, the amplification factor beta is equal to 8*-10*, the focus distance f' is equal to 20-32mm, the numerical aperture (NA) is more than 0.2, and the aperture angle omega is more than 2 degrees. The CaF2-free medium flat-field apochromatic metallographic microobjective has the following advantages: 1. the flat-field apochromatic effect is achieved; 2. the working distance is long; 3. the cost performance is high; and 4. the structure is simple.

Description

technical field [0001] The invention relates to a microscope objective lens, in particular to a CaF-free 2 Medium magnification plan apochromatic metallographic microscope objective. Background technique [0002] Microscopic objective lens is the most important part of metallographic microscope, and its imaging quality directly affects the performance of metallographic microscope. The plan apochromatic microscope objective is the microscope objective with the best image quality and the highest grade. In order to correct the primary axial chromatic aberration and the secondary spectrum at the same time in the objective lens, the conventional method is to introduce an optical crystal with low refractive index and low dispersion, such as calcium fluoride (CaF 2 ) etc. as manufacturing materials, but this will greatly increase the manufacturing cost. Considering the manufacturing cost and manufacturability, in recent years, using special glass (such as TF3) to replace or part...

AI Technical Summary

Problems solved by technology

However, the output of this special optical material is small, it is brittle, its physical and chemical properties are unstable, and it is more difficult to obtain large-sized materials.

The German Leica objective lens of similar foreign products is composed of 7 lenses, and the objective lens is composed of 6 lenses, all of which use CaF 2 material, so the price is higher, and the working distance of these two objectives is also small

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