Optical Lenses
A biconcave lens or double concave lens is an optical lens with two identical inward-bent spherical surfaces with equal radii of curvature. A double concave lens has a negative focal length and diverges a collimated light beam to the virtual focal point (that is the point at which the extension lines of the diverging light path intersect at the object side of the concave lens). The usages of Biconcave lenses are diverse, encompassing divergence of collimated or focused light beams, beam diameter modulation (e.g., Galilean beam expanders), the correction of spherical aberration of optical assemblies, and increasing the focal lengths of a lens group, etc. Due to its symmetric structure, a double concave lens works best when the conjugate ratio (object distance: image distance) is close or equal to 1:1. In such situations, the distortion, spherical/chromatic aberration, and coma could be offset as a result of the equilibrium of the lenses. Whilst, when the intended magnification ratio is <1/5 or >5, a plano concave lens will be a better alternative.
Hangzhou Shalom EO offers Off-the-shelf N-BK7 Biconcave Lenses, Off-the-shelf UV Fused Silica Biconcave Lenses, and Custom Biconcave Lenses made of BaF2, CaF2, MgF2, Ge, ZnSe, Sapphire, and other optical materials. The stock N-BK7 Bi-concave Lenses have four standard coating options: uncoated, 350-650nm, 650-1100 nm, and 1050-1580nm broadband anti-reflection (BBAR) coatings. Shalom EO’s stock UV Fused Silica Bi-concave Lenses only have uncoated versions so far. Custom V-coatings that exhibit optimized transmission and low-cost MgF2 AR coatings with various transmission wavelengths could be furnished onto UVFS biconcave lenses upon request.
