47-639 25 mm Dia. N-BK7/N-SF5 Achromatic Doublet; EFL=75mm VIS 0° 425-675nm

The 47-639 is a high-quality achromatic doublet lens, boasting a 25 mm diameter and a focal length of 75 mm, specifically designed for the visible light spectrum ranging from 425 to 675 nm. This lens is sourced from the renowned optical vendor, Edmund Optics, and is available for purchase through their website.

The lens is constructed from two types of Schott glass: N-BK7 and N-SF5. These materials are carefully selected to minimize chromatic aberration, a common issue in optical systems where different wavelengths of light are focused at different points. By combining these materials, the 47-639 achieves superior image quality and color correction.

The lens geometry is meticulously designed, with an inner radius of 0 mm, an outer radius of 0 mm, and a thickness at the edge of 6.97 mm. The first and second radii of curvature are 46.44 mm and -33.77 mm, respectively, while the third radius of curvature is -95.94 mm. The center thickness of the lens is 7 mm, with a reduced thickness of 2.5 mm at the center a position.

The 47-639 is coated with Edmund Optics' standard Vis-0 coating on both the front and back surfaces. This coating is specifically designed to optimize performance in the visible light spectrum, further enhancing the lens's color correction capabilities.