Eyepiece is also called ocular.
Eyepiece is a visual optical device that is used to observe an image formed by an objective lens after magnification.
Eyepiece can magnify the real image obtained by the magnification of the objective lens to form a clear and erect virtual image at the least distance of distinct vision. For aberration, eyepiece is usually composed of several lenses that correct the residual aberrations produced during imaging by the objective lens. Usually, eyepiece has a relatively larger field of view and angular magnification.
The eyepiece is provided with a diaphragm in the middle of the upper and lower lenses, or at the lower end of the lower lens, wherein micrometer, reticle, pointer and other accessories are mounted.
On the eyepiece there is engraved with the following marks: eyepiece type, magnification, field of view number, and the like. For example, eyepiece is engraved with PL10X/22;PL represents plane eyepiece, or flat-field eyepiece, 10X is the magnification, 22 represents the field of view, and the glasses mark represents high eye-point eyepiece, and C represents compensating eyepiece.
Generally, the outer diameter of the eyepiece of a compound microscope is 23.2mm, and stereo microscope can have a much larger field of view diameter because of its low magnification, so the outer diameter is mostly 30mm or 30.5mm.
The resolution capability of the microscope is determined by the numerical aperture of the objective lens, while the eyepiece plays only the magnification role. Therefore, for structures and details that can not be distinguished by the objective lens, the eyepiece still cannot distinguish even if it is magnifier again.
