The optical coating applied to the substrate is a major cost factor. More sophisticated coating techniques, which deliver better optical clarity, durability, and tighter spectral control, are significantly more expensive.

• Standard Evaporation: Lower cost, suitable for less stringent applications.

• Ion-Assisted Deposition (IAD): Medium to high cost. Improves film density and adhesion, resulting in more durable filters with less spectral drift due to environmental changes.

• Magnetron Sputtering (Sputtering): Highest cost. This advanced process provides the tightest control over layer thickness and deposition uniformity, essential for complex designs like narrowband optical filter or high OD bandpass filters and dichroic optical filter mirrors. The higher cost reflects longer production times and the use of expensive, high-vacuum equipment.