This is a 12.5 mm diameter achromatic doublet lens, manufactured by Edmund Optics, with a catalog number 12-931. The lens is mounted and features a Magnesium Fluoride (MgF2) coating on both the front and back surfaces, designed for the spectral range of 400-700nm.
The lens is a multiplet, specifically an achromatic doublet, which is a compound lens made of two separate materials to reduce chromatic aberration. The first material is N-BK7, a borosilicate crown glass, and the second is N-SF5, a dense flint glass. These materials are sourced from Schott, a leading manufacturer of optical glass.
The lens has an effective focal length (EFL) of 75mm, meaning it focuses light at a distance of 75mm from the lens center. The lens has a center thickness of 3mm and an edge thickness of 3.97mm. The first radius of curvature (r1) is 46.44mm, the second radius (r2) is -33.77mm, and the third radius (r3) is -95.94mm. The lens does not have an inner or outer radius.
The lens is in stock and available for purchase on the Edmund Optics website. The weblink provided leads directly to the product page for easy access and ordering.