The ND520A is a Neutral Density Filter from Thorlabs, designed with a circular base shape and a diameter of 0.5 inches. This filter is made from n-bk7 schott material and has a thickness of 1 millimeter. It is designed to work optimally at a wavelength of 633 nanometers.
The ND520A features a thin lens shape and is equipped with a front and back coating of tho nd20. This coating is responsible for the filter's optical density of 2.0. The filter is mounted with an SM05 thread, ensuring a secure and stable fit.
According to the vendor's information, the ND520A is currently in stock and can be purchased directly from Thorlabs via the provided weblink. The catalog number for this item is ND520A.