Calcium fluoride (CaF2) wide light transmission range (190nm-10 μ m), in ultraviolet, visible and infrared band has good transmittance.

It is often used for beam reflection, refraction, and deflection of images. The rectangular prism itself has a large contact area and has 45° and 90°.

A concave lens is composed of a plane and a concave sphere that can produce a negative spherical difference, which is often used in the system to expand the light beam or increase the focal length to balance the deviation of other lenses.

50.The main feature is that the focal length is positive, one side is a plane, and one side is a convex surface. In the optical system, the main role is beam expansion, imaging, beam collimation, focus alignment, etc.; usually used to reduce the beam, red

51.The main features of the crescent lens are: one side is convex and one side is concave. It can be either a converging lens or a divergent lens; determined by the refractive index, curvature, and radius. Mainly used for projection system, imaging system

氟化钙（CaF2）晶体硬度高，抗机械冲击和热冲击能力强，透光范围广（190nm-10μm），在紫外，可见和红外波段具有良好的透过率，所以被广泛应用于激光、红外光学，紫外光学等领域，具体可用作电力红外窗口、气体液体检测仪器、激光系统、成像系统等。

52.It does not change the magnification of the system. A protection window usually used in electronic sensors or external environments.

104.The double-convex lens features a positive focal length consisting of two convex surfaces with equal radii; commonly used for imaging relay systems and for imaging objects at a limited conjugate distance.

105.Double-concave lens is composed of two concave surfaces with equal side radius of curvature, which is often used for lens beam expansion, projection, and expanding the focal length of the optical system.

Two planes have angles; two non-parallel planes can avoid the interference effect (Etalon effect) reflected by the front and rear surfaces of the high parallelism window