The 89-204 is a double-convex lens, characterized by its spherical shape and circular base. This lens, sourced from Edmund Optics, boasts a diameter of 50mm and a focal length of 250mm, making it a versatile choice for various optical applications. The lens is fabricated from n-BK7 Schott, a high-quality optical glass known for its excellent transparency and homogeneity.
The lens features a double-convex geometry, with radii of curvature of 257.57mm and -257.57mm for the first and second surfaces, respectively. This geometry results in a back focal length of 248.37mm and an effective focal length of 250mm. The lens has a central thickness of 4.93mm and an edge thickness of 2.5mm, providing robustness and durability.
The 89-204 lens is coated with EDM VIS-EXT on both the front and back surfaces. This coating enhances its transmission capabilities within the visible spectrum, specifically between 350nm and 700nm. The coating ensures high-quality image reproduction by minimizing surface reflections and improving light transmission.