FELH0400 Dia:25.0 mm Premium Longpass Filter; Cut-On Wavelength: 400nm

The FELH0400 is a high-quality longpass filter manufactured by Thorlabs, a leading global supplier of photonics equipment. This filter, with a diameter of 25.0 mm and a thickness of 3.5 mm, is designed for use in a variety of optical systems where longpass filtering is required.

The FELH0400 filter has a cut-on wavelength of 400nm, meaning it allows transmission of wavelengths longer than 400nm while blocking shorter wavelengths. This specific model is made from UVFS material, identified as MAL-1965 in Thorlabs' catalog. The filter's coating, applied to both the front and back surfaces, is a premium AR coating designed to reduce surface reflections and improve transmission.

The filter's shape is described as a Thin Lens, which suggests it may have some degree of optical power, although this is not explicitly stated in the provided data. The physical data indicates that the filter has no cut-off wavelength, which is typical for longpass filters.

This filter is currently in stock and available for immediate purchase from Thorlabs' website. Detailed product information, including technical specifications and datasheets, can be found at the provided weblink.