This is the FND-15C02-50, a 15 mm diameter unmounted Neutral Density Filter from OptoSigma. The filter is made of N-BK7 Schott, a high-quality borosilicate glass known for its excellent optical properties, making it suitable for various applications in the visible spectrum.
The filter features a reflective neutral density coating on both the front and back surfaces, denoted as 'opt fnd-50'. This coating is designed to reduce the intensity of light passing through the filter without altering its color balance, providing a uniform attenuation across the visible spectrum (400-700nm). The coating also offers high damage threshold and excellent environmental stability.
The filter has a thickness of 2mm, which is considered 'thin' in optical terms. This thinness can be beneficial in certain applications where maintaining a compact setup is crucial. Despite its thinness, the filter maintains high optical quality and durability.
The FND-15C02-50 is currently in stock and available for purchase through the OptoSigma website. The link to the product page is provided in the item data for your convenience.