A biconcave lens with one concave surface and one double-sided surface, possessing a positive focal length, is commonly used for applications such as reducing light beams, reducing focal length, or enlarging images. To reduce spherical aberration, when using a double concave lens for collimated beam focusing, the beam should be incident on the lens surface; When used for point light source collimation, the beam is incident on both sides.

A biconcave lens focuses light into a single point. Commonly used for aiming and focusing monochromatic light sources. When in use, place the concave surface facing the incident light. Wangxinsheng provides double concave lenses coated with anti reflective film. Germanium, silicon or zinc selenide substrates are suitable for infrared applications, and fused silica is suitable for ultraviolet applications.