The 69-649 is a 25mm diameter, 25mm focal length plano-convex lens, designed for use in the 3-5µm spectral range. This lens is sourced from Edmund Optics, a leading vendor in the optical components industry.
The lens is made of Germanium burnett, a material known for its high refractive index and transparency in the infrared spectrum. The plano-convex geometry, where one side is flat and the other is curved, is ideal for applications that require a collimated beam or a focused spot.
The lens features a broadband anti-reflection (BBAR) coating, specifically the EDM ARCEDGERMANIUM35 coating, on both the front and back surfaces. This coating reduces surface reflections, thereby increasing transmission and minimizing losses. The coating is designed to operate effectively across the 3-5µm wavelength range.
The lens has a center thickness of 3mm and an edge thickness of 1.95mm, providing structural rigidity while maintaining a compact profile. The effective focal length (EFL) is 25mm, and the radius of curvature (R1) is 75.1mm. The back focal length (BFL) is 24.25mm, and the lens has no inner or outer radius, indicating a uniform thickness across the aperture.