k9 biconcave lens glass optical lens

k9 biconcave lens glass Optical Lens

Double Concave Lens is similar to flat concave lens. The focal length is negative, but the light incident in parallel diverges outward. The curvature radii of the two sides of double concave lens are equal. It is generally used for beam expansion and projection.

       Example with BK7 material：These N-BK7 biconcave lenses are available uncoated or with one of five antireflection coatings (-A, -AB, -B, -C, or -D), which reduces the amount of light reflected from each surface of the lens (see the Selection Guide table below for coating option). Since approximately 4% of the incident light is reflected at each surface of an uncoated substrate, the application of an AR coating improves transmission, which is important in low-light applications, and prevents the undesirable effects (e.g., ghost images) associated with multiple reflections. Having optics that are AR coated on both surfaces is particularly desirable for applications utilizing multiple optical elements. Please see the Graphs tab for additional coating information.

N-BK7 bi-concave lens Selection Guide
Coating name	wavelength band
Uncoated	Uncoated
A Coating	350nm-700nm
AB Coating	400nm-1100nm
B Coating	650nm-1050nm
C Coating	1050-1700nm
D Coating	1650nm-3000nm

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