This is a Plano-Concave Lens, model SLB-15-30NIR1, sourced from OptoSigma. The lens has a diameter of 15.0 mm and a focal length of -30.0 mm, making it a negatively powered lens. The lens is made of n-bk7 schott material, a popular choice for its high refractive index and low dispersion.
The lens features a plano-concave geometry, meaning one side is flat while the other is curved inward. The curvature of the concave side is represented by a radius of -15.57 mm. The lens's thickness at the edge is 3.9 mm, while at the center it is 2 mm. The back focal length (BFL) is -31.3 mm.
The lens comes with a coating of opt ir1 on both the front and back surfaces. This coating is specifically designed for the wavelength range of 633-1064nm, making it suitable for near-infrared (NIR) applications.
The lens is currently in stock and available for purchase. For more information, please refer to the vendor's website using the provided weblink.