45-258 25 mm Dia. N-BK7 Precision Protective Flat Window; t=4 mm MgF2 400-700nm

This product is a 25 mm diameter, 4 mm thick N-BK7 precision protective flat window, offered by the renowned optical components vendor, Edmund Optics. The window is designed to provide robust protection for optical systems while minimally affecting the system's performance due to its high-quality materials and coatings.

The window is made of N-BK7, a popular borosilicate crown glass known for its excellent optical properties. This material is often used in high-precision optical applications due to its low optical dispersion and high Abbe number. The window's 4 mm thickness provides sufficient protection without adding unnecessary weight or bulk to the optical system.

Both the front and back surfaces of the window are coated with MgF2, a broadband anti-reflection coating that operates over the 400-700 nm spectral range. This coating reduces surface reflections, thereby improving transmission and minimizing unwanted glare and ghosting effects. The MgF2 coating is standard, ensuring consistent performance and reliability.

The window's geometry is that of a thin lens, suggesting that it may have some focusing properties. However, its primary function is protective, and any lens-like properties should be considered secondary.