A flat concave lens is a special type of lens that has the characteristics of one side being a sphere and the other side being a plane, and the middle is thinner than the two sides. This type of lens has a negative focal length and is mainly used to diverge a beam of parallel light. Its materials include K9 glass, fused silica, zinc selenide, zinc sulfide, germanium, silicon, lithium fluoride, calcium fluoride, barium fluoride and magnesium fluoride. So which side of the flat concave lens is facing parallel light?
The concave surface of a flat concave lens should face parallel light. When using a flat concave lens, the concave surface should face the direction of incident light, while the flat surface should face the focal plane to be processed. In this way, when parallel light is incident on a flat concave lens, it will be diverged by the concave surface of the lens, while the outgoing light cannot converge into a single point, but forms a virtual focus. This characteristic makes flat concave lenses widely used in beam collimation, increasing (decreasing) focal length, or expanding (reducing) images.
The above is an answer to which side of the flat concave lens faces parallel light. We hope it is helpful to you. If you have any questions, please feel free to consult online or leave a message.
