Multi-period Nested Ring Array Optical Window for Diffraction Control

The invention divides the traditional single-period metal grid into multiple periods with different grid densities. The first period has a first grid density optimized for electromagnetic shielding, while the second period has a second grid density optimized for reducing diffraction. This segmentation allows each period to specialize in different functions, resolving the contradiction between shielding capability and imaging quality.

Different regions of the optical window are assigned different grid densities. The first period covers regions where electromagnetic shielding is most critical, while the second period covers regions where diffraction control is most important. This local quality approach allows optimal performance in different spatial zones, simultaneously achieving strong shielding and high imaging quality.

The invention employs a multi-period structure where the first period and second period are arranged alternately. This periodic action with varying grid densities creates a diffraction pattern where high-order diffraction energy is distributed across multiple periods rather than concentrated in a single period, thereby reducing the harmful effects on optical imaging while maintaining electromagnetic shielding.

The invention converts the harmful concentrated high-order diffraction energy into a beneficial distributed pattern. By using multiple periods with different grid densities, the diffraction energy that would normally be concentrated and harmful is instead distributed across multiple regions, reducing peak intensity and improving overall imaging quality while preserving shielding effectiveness.