Photoreactive Material Layer Dual-Surface Alignment

The light radiation process is segmented into two separate actions: radiating light on the upper surface and radiating light on the lower surface. This segmentation allows each surface to be treated independently, ensuring that both the upper and lower portions of the photoreactive material layer achieve uniform alignment, thereby resolving the contradiction between manufacturing simplicity and alignment uniformity.

The solution transitions from a single-sided (one-dimensional) light radiation approach to a dual-sided (two-dimensional) approach. By radiating light from both the upper and lower surfaces simultaneously or sequentially, the patent achieves uniform alignment throughout the entire thickness of the photoreactive material layer, eliminating the alignment non-uniformity that occurs with single-surface radiation.

Instead of applying a single high energy exposure that causes side reactions, the patent applies two partial exposures: one on the upper surface and one on the lower surface. Each exposure uses lower energy, sufficient for its local alignment task, avoiding the excessive energy that would trigger harmful side reactions while still achieving the desired alignment properties.

The patent changes the exposure parameters by distributing the total required alignment energy across two separate lower-energy exposures applied to different surfaces. This parameter modification (from one high-energy exposure to two lower-energy exposures) maintains effective alignment while reducing the intensity that causes side reactions.

The manufacturing process is segmented to include light radiation on both upper and lower surfaces. This segmentation ensures that the photoreactive material achieves uniform alignment throughout, which is necessary for obtaining the required refractive index and contrast ratio, while keeping each individual radiation step relatively simple.

The patent moves from single-surface to dual-surface light radiation, adding a dimensional aspect to the manufacturing process. This dual-sided approach ensures uniform alignment and proper optical properties (refractive index and contrast ratio) without significantly increasing manufacturing complexity, as both surfaces can be treated in parallel or sequence.