47-702 15 mm Dia. N-BK7/N-SF5 Achromatic Doublet; EFL=50mm VIS 0° 425-675nm

The 47-702 is a high-quality achromatic doublet lens, boasting a 15 mm diameter and an effective focal length (EFL) of 50mm, specifically designed for the visible light spectrum ranging from 425 to 675nm. This lens is sourced from the renowned optical vendor, Edmund Optics, and is available for purchase through their official website.

The lens is constructed from two types of glass, N-BK7 and N-SF5, both from Schott, ensuring superior optical performance. The front and back surfaces of the lens are coated with the EDM VIS-0 standard curve coating, providing excellent transmission and protection against environmental factors.

The lens geometry is meticulously designed, with a thickness of 5.12mm at the edge and 5mm at the center, and a central thickness of 1.5mm. The lens features three radii of curvature: r1 at 26.81mm, r2 at -23.82mm, and r3 at -90.79mm. The inner and outer radii are both zero, indicating a circular shape.

This achromatic doublet lens is a multiplet, meaning it is composed of multiple optical elements. This design helps to correct chromatic aberration, a common issue in lenses where different wavelengths of light are focused at different points. By using two types of glass with different dispersion properties, the 47-702 effectively minimizes this aberration, ensuring sharp and clear images across the entire visible light spectrum.