Our standard size is nominally 25mm diameter x 3-7mm thick mounted in a polyamide holder with 21mm diameter clear aperture (Note: Useful aperture for some blocking filters is different and the holders for these are made of black anodised aluminium). The particular grade of material used for the holder has been chosen because it has a high maximum operating temperature and is stabilised against infra-red and ultra-violet radiation. Other common sizes are 23mm diameter x 1 mm thick, 25mm diameter x 1mm thick and 1 inch diameter x 1mm thick (all unmounted).

Custom Sizes

From 2mm x 2mm square up to ~50mm diameter, depending on type of coating. For custom sizes we manufacture on 25.4mm discs and then cut as required. For example, semicircular, quadrants, squares, rectangles or custom shapes. However, in general, where circular filters are required we tend to manufacture on pre-cut discs. In addition where specialist applications are required (e.g. operating at cryogenic temperatures) we can manufacture on the custom shaped pre-cut substrates by using specialist tooling.