The FEL0450 Dia:1 Longpass Filter, offered by Thorlabs, is a circular filter designed with a diameter of 25.4 mm and a thickness of 3.5 mm. This filter is made of soda lime ru clear material and features a thin lens shape.
The Longpass Filter is a type of optical filter that passes longer wavelengths of light and blocks shorter wavelengths. In this case, the FEL0450 has a cut-on wavelength of 450nm, meaning it allows wavelengths of 450nm and longer to pass through while blocking wavelengths shorter than 450nm. The cut-off wavelength is 0nm, indicating that it blocks all wavelengths shorter than 450nm.
The filter's coating is applied to both the front and back surfaces, with the front coating being 'tho fel0450' and the back coating also being 'tho fel0450'. This coating enhances the filter's performance and durability.
According to the vendor's website, this item is currently in stock, and more detailed information can be found at the provided weblink: https://www.thorlabs.com/thorproduct.cfm?partnumber=FEL0450.