Plane concave lens is a negative lens with a negative focal length, and the parallel light beam will diverge after incident on the plane concave lens. The outgoing light rays cannot be converged into a single point, but seem to diverge from a virtual image point located in the physical space. When the absolute conjugate ratio is greater than 5:1 or less than 5:1, the plano concave lens is negative lenses of optimal shape for reducing spherical aberration, comatic aberration, and aberration.
The concave surface of a plane concave lens should be oriented toward the object, but when applied to a high-energy laser system, it should be placed in the opposite direction to reduce the likelihood of remaining reflected light from the surface gathering. The plano concave lenses are spherical on one side and flat on the other. The middle is thinner than the sides.
A plane concave lens has one side concave and one side flat and has a negative focal length. Typically it is used for beam collimation, increasing (decreasing) focal length, or expanding (decreasing) an image. In order to obtain a smaller spherical aberration, when the incident beam is collimated, the collimated beam should be incident on the concave surface of the plane concave lens.
The plane concave lenses have negative focal lengths and are often used in applications such as imaging or beam collimation. Coated lenses are also widely used in visible light and near-infrared applications. Conventional lens sizes are: 412.7mm, 25.4mm, 50.8mm, and customized biconvex lenses can be produced according to requirements of customer project.