49-328 12.5 mm Dia. N-BK7/N-SF5 Achromatic Doublet; EFL=50mm VIS-NIR 400-1000nm

The 49-328 is a high-quality achromatic doublet lens, designed and manufactured by Edmund Optics. This lens is specifically engineered for use in the visible (VIS) and near-infrared (NIR) spectrum, with a wavelength range of 400-1000nm. The lens boasts a 12.5 mm diameter and an effective focal length (EFL) of 50mm, making it a versatile choice for a wide range of optical applications.

The lens is constructed from two types of glass: N-BK7 and N-SF5, both from Schott. This combination is used to correct chromatic aberration, a common issue in optical systems where different wavelengths of light are focused at different points. The achromatic design ensures that the lens focuses both red and blue light to the same point, providing sharp, clear images.

The lens geometry is carefully designed to optimize performance. It has a thickness of 4.06mm at the edge, with a central thickness of 3.5mm. The lens features three radii of curvature: r1 is 30.73mm, r2 is -22.32mm, and r3 is -64.75mm. These radii, combined with the lens thickness and glass types, contribute to the lens's excellent optical performance.

The lens is coated with Edmund Optics' VIS-NIR coating (edm visnir0sp2002000), which is applied to both the front and back surfaces. This coating is designed to enhance the lens's transmission in the VIS-NIR range, reducing reflections and improving overall system efficiency.