Stage micrometer is a special slide with a small circle in the center. A division is carved in the circle, and the line with a length of 1 mm is divided into 100 small grids, each of which is equal to 10 μ M. The objective micrometer is a special slide with a small circle in the center. A division is carved in the circle, and the line with a length of 1 mm is divided into 100 small grids, each of which is equal to 10 μ M.

Generally, the reticle is installed on the focal plane of the right eyepiece of the telescope. It is a thin glass with dense reticle lines on its surface. Theoretically, this thin glass also participates in the imaging and extends the focal length of the objective lens, which will have more or less influence on the length of the right eyepiece. The reticle board has high requirements for cleanliness. Any small dust will produce large black spots during observation. At the same time, the accuracy of the installation position of the reticle board is very high. Therefore, it should not be disassembled as far as possible. If it is disassembled, it must be restored as it is.