Fabry-Perot Filter Foreign Matter Removal

The patent segments the Fabry-Perot interference filter into distinct components: a substrate, a fixed mirror layer, and a movable mirror layer separated by a gap. This segmentation allows the movable mirror to be treated as a delicate membrane structure requiring special handling, while the fixed mirror and substrate provide structural support. The gap itself acts as a protective barrier that prevents direct contact between the two mirror layers, enabling selective application of removal forces on the movable mirror without affecting the fixed mirror.

The patent applies local quality by creating a membrane-shaped movable mirror with specific local properties (fragility, flexibility) distinct from the rigid fixed mirror and substrate. The movable mirror portion is designed with localized membrane characteristics in the gap region, allowing it to be manipulated differently from other parts of the filter. This local differentiation enables targeted foreign substance removal methods that account for the specific vulnerability of the membrane structure.

The patent implements preliminary action by detecting foreign substances on the movable mirror before final assembly and performance testing. The detection step occurs while the filter is still in the manufacturing process, allowing for timely removal of contaminants. This preliminary detection and removal prevents foreign substances from affecting optical performance in finished products, thereby improving yield by salvaging filters that would otherwise be discarded.

The patent converts the potential harm of foreign substance presence into a benefit by establishing a targeted removal process. Instead of discarding all filters with detected contaminants, the system uses the detection information to apply precise removal actions only where needed. This approach transforms what would be a defect-leading-to-rejection scenario into an opportunity for corrective action that improves both quality and yield.