The base material or optical substrate is a primary cost driver. Common materials like BK7 are less expensive, while fused silica costs more due to its superior transmission, thermal stability, and low coefficient of thermal expansion, making it ideal for demanding applications. Highly specialized materials, such as sapphire or ZnSe (often used for far-infrared or high-power laser systems), significantly increase the cost. The cost is tied to:
Raw Material Purity: High-purity optical glass is more expensive but ensures better optical homogeneity and minimal defects.
Processing Difficulty: Harder or specialized materials require more complex, time-consuming grinding and polishing steps, leading to higher manufacturing costs.
Refractive Index Consistency: Tighter control over the refractive index across batches adds to the material's premium.
