Dielectric coatings. Customer-specific solutions are also available for IR long-pass filters.
Long-pass infrared filters, unlike semiconductor filters, are constructed from stacks of thin layers. OD 3 rejection in the suppression range is not as high as it is with semiconductor filters, but it has the advantage of free choice of slope position.
Now you can check online which optical filters are in stock at our partner NOC - Northumbria Optical Coatings Ltd. You can directly place an order which, as usual, will be handled through us.