N-BK7 is an excellent lens material for most visible and near infrared applications. It is the most common borosilicate crown optical glass, and it provides great performance at a good value. Its high homogeneity, low bubble and inclusion content, and straightforward manufacturability make it a good choice for transmissive optics. N-BK7 is also relatively hard and shows good scratch resistance. The transmission range for BK 7 is 380 to 2100 nm. It is not recommended for temperature sensitive applications, such as precision mirrors. For more information, refer to our optical materials technical note.

Our AR.33 laser line V-coating offers the lowest reflectance at 1064 nm for maximum transmission while maintaining high durability and high damage resistance. Valuable laser energy is efficiently transmitted through the plano-convex lens rather than lost to surface reflection and scattering. The trade off to its superior performance is the minimal laser line wavelength range.

Bi-Concave lenses are the best choice where object and image are at absolute conjugate ratios closer to 1:1 with converging input beam. The output rays appear to be diverging from a virtual image located on the object side of the lens. The distance from this virtual point to the lens is known as the focal length. Similar to the Plano-Concave lenses, the Bi-concave lenses have negative focal lengths, thereby causing collimated incident light to diverge. Bi-Concave lenses have equal radius of curvature on both side of the lens. They are generally used to expand light or increase focal length in existing systems, such as beam expanders and projection systems.