FND-20C02-5 20 mm Dia. Unmounted N-BK7 Visible Reflective Neutral Density Filter; t=2mm 400-700nm

The FND-20C02-5 is a high-quality Neutral Density Filter, unmounted and with a 20 mm diameter, sourced from the renowned optical components manufacturer, OptoSigma. This filter is designed for use in the visible light spectrum, specifically between 400 and 700 nanometers, making it suitable for a wide range of optical applications.

The filter is made from N-BK7, a high-grade borosilicate glass manufactured by Schott AG, known for its excellent optical properties and durability. The N-BK7 material ensures high transmittance and low absorption across the visible spectrum, making it an ideal choice for applications requiring high-quality, neutral light attenuation.

The filter features a thickness of 2mm, providing robustness and stability. It is coated on both the front and back with OptoSigma's FND-5 coating, a reflective neutral density coating that further enhances the filter's performance by reducing reflections and increasing transmission.

The filter's shape is that of a thin lens, optimized for minimal distortion and high optical performance. The unmounted design allows for easy integration into existing optical systems, providing flexibility in system design and setup.