Infinity-corrected Optical System
In an infinity-corrected optical system, a light beam emitted from a specimen passes through the objective lens which does not form an image and enters as an infinity parallel beam in the tube lens which forms an intermediate image. In a finite correction optical system, the objective lens forms an intermediate image by itself.
Principle Diagram of Infinity-corrected Optical System and Finite Correction Optical System
Advantages of Infinity-corrected Optical System
An infinity-corrected optical system basically has the following advantages because a parallel light beam passes between the objective lens and tube lens.
A magnification does not change even if the distance between the objective lens and tube lens is changed. Even if a parallel flat plate is inserted between the objective lens and tube lens, the parfocal point remains unchanged and delivers no image shifting occurs.
The two advantages above-mentioned are extremely significant ones on the occasion of configuring a microscope optical system, and it has been said for a long time that "an infinity-corrected optical system is an ideal microscope optical system". If you make the most of these advantages, you can configure an optimal optical system by optionally taking in and out an intermediate lens unit within the parallel beam section between the objective lens and tube lens.
* The parfocal distance of UIS2/UIS objective lens is 45 mm, and the focal length of the tube lens is 180 mm.
Figure Showing the Advantages of an Infinity-corrected Optical System
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