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Finite Optical System | Finite Optical System

Key Words: resolution, working distance, Infinity optical system, CFI60

Definition:A microscope optical system where the distance between the nosepiece opening to the ocular seat in the eyepiece tubes is fixed


Finite, or fixed tube length, microscopes have a fixed distance (the mechanical tube length) from the nosepiece opening where the objective barrel is secured, to the ocular seat in the eyepiece tubes. Finite tube lengths are usually 160 mm or 170 mm in length. Light passing through the objective is directed toward the intermediate image plane (located at the front focal plane of the eyepiece) and converges at that point, undergoing constructive and destructive interference to produce an image. When optical components are inserted into the light path of a finite system, the tube length effectively increases. This may introduce spherical aberration into the optical system. Objectives designed for finite systems are not readily interchangeable with those of infinity systems and vice versa.


Finite microscope systems can be used for both biological and industrial applications although they do not have the easy of use and flexibility of infinite optical systems when optical accessories need to be inserted into the light path.


Objectives and other optical accessories designed for finite optical systems are not readily compatible with Nikon's CFI60 infinity optical system.


Nikon recommends it proprietary CFI60 (infinity) optical system for maximum flexibility, brightness and clarity in biological and industrial imaging applications.


Optical components: [microscopyu]

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