The slit lamp microscope is an essential and important instrument for eye examinations. The slit lamp microscope is composed of an illumination system and a binocular microscope. It can not only make superficial lesions be observed very clearly, but also can adjust the focus and the width of the light source to make an "optical section" so that the lesions of deep tissues can also be clearly displayed .
The structure of the slit lamp is mainly composed of two parts, namely the "slit lamp" and the "microscope". In order to facilitate the slit light source to illuminate each part of the eye from different angles, and the microscope to observe the eye from different angles, both the slit lamp and the microscope are required to have sufficient left and right swing angles mechanically. The light source of the slit lamp requires that the edge of the slit must be very flat, the slit must be clearly imaged on the vertical plane of the center of the circle that swings from side to side, and the focus of the microscope must also be focused on the vertical plane of the center of the circle.