Before production begins, the specifications of the optical filter must be clearly defined. This includes the wavelength range, bandwidth, transmission requirements, size, and shape. Advanced software is often used to model the filter's performance and optimize its design.

The substrate material, which can be glass, plastic, or another transparent material, is prepared. This involves cutting the substrate to the required size and shape and then polishing it to achieve the necessary optical quality. The surface must be free of imperfections to ensure the filter's effectiveness.

This is a critical step for many types of optical filters, especially interference filters. Thin layers of different materials are deposited on the substrate in a vacuum environment using techniques such as sputtering, evaporation, or chemical vapor deposition. The specific materials and thicknesses of the layers determine the filter's optical properties.

After deposition, the layers are inspected for uniformity and adherence to specifications. This can involve sophisticated measurement techniques to analyze the thickness and refractive index of the layers.

If the filter consists of multiple components (e.g., several coated substrates stacked together), these are assembled. This step must be performed with precision to ensure the components are correctly aligned.

The finished filter is subjected to rigorous testing to ensure it meets the required specifications. This includes measuring its transmission and reflection properties across the relevant wavelength range, verifying its physical dimensions, and assessing its durability.