Holographic Projector Beam Alignment via Divergence Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Holographic display systems, particularly in vehicles, face challenges in aligning and sizing RGB images due to wavelength-dependent diffraction angles, leading to misalignment and size differences, which are exacerbated when projecting over large distances, such as in head-up displays.
Innovation Solution
The system adjusts the divergence angles of RGB light beams using lenses and non-periodic photon sieve layers, and encodes prism and lens holograms to align and resize the images, ensuring they overlap with the same center point, using spatial light modulators and a control module to combine the beams for a unified image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If holographic display systems project RGB images using different wavelengths of light, then the system can provide full-color holographic display, but the wavelength-dependent diffraction angles cause color misalignment and size differences
Solution Approach 1:
The patent adjusts the divergence angles of RGB light beams as a parameter change to compensate for wavelength-dependent diffraction angle differences. By modifying the divergence angle parameter of each color channel, the system achieves uniform diffraction angles and eliminates color misalignment while maintaining full-color display capability
Solution Approach 2:
The patent replaces physical mechanical alignment adjustments with software-encoded holograms (prism and lens holograms) that are digitally applied to spatial light modulators. This substitution allows precise alignment correction through computational methods rather than mechanical adjustments
2Length of stationary object
If the system projects over large distances to enhance visibility, then the viewing distance is increased, but the misalignment and size differences are exacerbated
Solution Approach 1:
The patent applies preliminary correction by adjusting divergence angles and encoding alignment holograms before the light beams are projected over long distances. This preliminary action ensures that alignment is established upfront, preventing misalignment from being exacerbated during long-distance projection
3Productivity
If the system uses multiple spatial light modulators for RGB channels, then the system can process multiple wavelengths simultaneously, but the complexity of aligning and sizing multiple beams increases
Solution Approach 1:
The patent merges the alignment and sizing functions into a unified computational approach using software-encoded holograms that simultaneously handle both alignment and size correction for multiple beams. This merging reduces operational complexity while maintaining multi-wavelength processing capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively corrects color misalignment and size differences, providing a single, aligned image at the viewer's eye box, even when projecting over large distances, enhancing the clarity and coherence of holographic displays in vehicles.
Implementation Method 1
The first lens is disposed to adjust a divergence angle of one of the first light beam, the second light beam or the third light beam, such that diffracted light out of each of the spatial light modulators is at a same diffraction angle
Implementation Method 2
The spatial light modulators are configured to respectively diffract the first light beam, the second light beam and the third light beam
Implementation Method 3
The combiner is configured to combine the phase hologram beams to provide a combined phase hologram beam projected for viewing a combined graphic image
Data Source
AI summary
A holographic projection system including first, second and third light sources, SLMs, a lens, a combiner and a control module. The first, second and third light sources generate respective light beams. The light beams have respective wavelengths. The SLMs respectively diffract the light beams. The lens is disposed to adjust a divergence angle of one of the light beams, such that diffracted light out of each of the SLMs is at a same diffraction angle. The SLMs encode phase holograms including respective versions of a graphic image based on light generated by the light sources including light output from the lens to provide phase hologram beams. The combiner combines the phase hologram beams to provide a combined phase hologram beam projected for viewing a combined graphic image. The control module encodes a prism hologram on one of the SLMs to align outputs of the SLMs.