This is the FND-50C02-70, a 50 mm diameter, unmounted Neutral Density Filter from OptoSigma. The filter is made of N-BK7 Schott, a high-quality optical glass known for its excellent transmittance and low auto-fluorescence. The filter's primary function is to reduce the intensity of light, making it ideal for use in high-intensity lighting environments.
The filter features a reflective neutral density coating on both the front and back surfaces, identified as 'opt fnd-70'. This coating provides a uniform attenuation of light across the visible spectrum, specifically designed for the 400-700nm range. The coating is thin, with a thickness of 2mm, which helps to minimize any potential distortions or aberrations.
The shape of the filter is a thin lens, which is optimal for applications where minimal thickness and weight are crucial. The filter is unmounted, providing users with the flexibility to mount it in their preferred system or housing.
According to the vendor's information, this item is currently in stock and can be purchased directly from the OptoSigma website using the provided weblink.