NE240B 2 in x 2 in Absorptive ND Filter; Optical Density 4.0

The NE240B is a Neutral Density Filter from Thorlabs, measuring 2 in x 2 in with an optical density of 4.0. This filter is designed to reduce the intensity of incident light without altering its color composition, making it an essential tool for various optical applications.

The filter is made of N-BK7 Schott, a high-quality borosilicate glass known for its excellent optical properties. It has a thickness of 2.8 mm, providing durability and stability. The rectangular shape of the filter allows for versatile mounting options, enhancing its usability in different setups.

The NE240B features a thin lens shape, which is beneficial for maintaining the optical path's integrity. The front and back of the filter are coated with THo NE40A, a specialized absorptive coating that provides the desired optical density. This coating ensures high transmission and low reflection, contributing to the filter's overall performance.

The filter's geometry, including its width and height of 50.8 mm, is designed to fit standard optical components, making it a compatible choice for many systems. The vendor, Thorlabs, is a reputable manufacturer known for its high-quality optical components, ensuring reliability and performance.