Holographic Optical Element Calibration for AR Smart Glasses

The patent extracts the essential function of image projection from complex DLP chip systems and implements it using a simplified laser scanner combined with a holographic optical element. The laser scanner unit scans laser beams to generate image information, while the HOE diffracts and focuses the light directly onto the retina, eliminating the need for DLP chips and associated complex optics.

The patent replaces the mechanical micromirror array of DLP systems with a laser scanner that uses galvanometer mirrors or MEMS to deflect laser beams. This substitution simplifies the system by using a single movable mirror instead of a complex micromirror array, reducing device complexity while maintaining projection capability.

The patent removes heavy components from traditional projection systems (DLP chips, complex lens assemblies) and retains only the essential elements: a compact laser source, a small scanner, and a thin holographic optical element. This extraction dramatically reduces the weight and form factor while preserving the core image projection function.

The patent uses a holographic optical element in the form of a thin film or coating applied to the eyeglass lens. This thin-film approach replaces bulky traditional optics, enabling the projection system to be integrated into lightweight smart glasses without significant weight increase.

The patent incorporates alignment marks directly on the holographic optical element and uses a calibration routine that scans the laser over these marks to automatically determine the relative orientation of the scanner and HOE. This preliminary alignment feature allows for precise positioning to be achieved through software calibration rather than complex mechanical alignment during manufacturing.

The system performs self-calibration by scanning the laser over alignment marks on the HOE and automatically computing the transformation between scanner coordinates and HOE coordinates. This self-service calibration approach eliminates the need for manual precision alignment, making the system tolerant of manufacturing variations while maintaining compact dimensions.

The patent embeds alignment marks directly on the holographic optical element during manufacturing, creating a built-in reference system. The calibration routine scans the laser over these pre-positioned marks to automatically determine the relative orientation and scaling between the scanner and HOE, transforming a potentially complex alignment problem into a straightforward measurement task.

The patent replaces complex mechanical alignment mechanisms with a software-based calibration system that uses laser scanning and image processing to determine optical component orientations. This substitution reduces mechanical complexity while achieving high calibration accuracy through computational methods.