For a cover glass, it varies in size, and for the minimum size of a cover glass, it is eighteen times eighteen centimeters. And cover glass and other forms of different specifications of the glass, and is often the case when we detect microscopic using microscope is according to different purposes or conditions to choose different cover glass for microscopy, so for the thickness of the cover glass is usually based on micro detection can be carried out at low and high power of a problem of thick and thin, But when we use the oil mirror, the thickness of the cover glass can not be too thick. However, it can not be too thin. The thickness of cover glass we usually choose to use is too thin or too thick, which will affect the quality of microscopic image imaging. Therefore, cover glass between 0.17 mm and 0.18 mm is usually used for microscopic detection.