Light-Field Projector With Virtual Pixel Image-Plane Alignment
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Solution Overview
Problem
Existing light-field displays face limitations in resolution due to finite apertures of pinholes and lenses, which restrict the depth of field and effective resolution, especially when focusing on virtual pixels that are not coincident with the image source plane.
Innovation Solution
A light-field projector with an image source and imaging optical element that adjusts the spatial distribution of pixel components and shifts the projector image plane to coincide with the virtual pixel image, allowing for viewer-independent light-field projection with controlled focal depth and enhanced resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If light-field components are projected through small pinholes to increase depth of field, then the depth of field is improved, but the resolution is reduced due to diffraction on the aperture
Solution Approach 1:
The invention divides the single aperture into multiple spatially disparate sub-apertures (pinholes), each projecting a light-field component. This segmentation allows the system to achieve both large depth of field (through small individual pinholes) and high resolution (through the combined aperture of all sub-apertures), as the eye integrates signals from multiple pinholes while maintaining focus across different depths
Solution Approach 2:
The invention transitions from a single aperture in one dimension to multiple apertures arranged in a two-dimensional array. This dimensional change allows the system to simultaneously achieve the depth of field benefits of small apertures and the resolution benefits of a large effective aperture, by distributing multiple small pinholes across a larger spatial footprint
2Manufacturing precision
If the aperture is made large to improve resolution, then the resolution is improved, but the depth of field is reduced
Solution Approach 1:
The large aperture is segmented into multiple small sub-apertures (pinholes) arranged in a array. Each small pinhole provides large depth of field, while the collective arrangement of multiple pinholes creates a large effective aperture that improves resolution. The eye integrates the signals from all pinholes to achieve both properties simultaneously
Solution Approach 2:
The invention merges the outputs of multiple small pinholes into a single integrated image on the retina. By combining the light-field components from multiple spatially disparate pinholes, the system achieves an effective aperture larger than any individual pinhole, thereby improving resolution while maintaining the depth of field benefits of small individual apertures
3Device complexity
If sequential projection of light-field components is used to simplify the system, then the device complexity is reduced, but the wavefront reconstruction is impossible because interference requires coincidence of wave front components
Solution Approach 1:
The system uses sequential (time-sequential) projection of light-field components through different pinholes, with each pinhole projecting its component during a specific time interval. This periodic action simplifies the device by using a single pinhole array rather than requiring all pinholes to be active simultaneously, while still enabling wavefront reconstruction through temporal integration by the eye
Solution Approach 2:
The human eye performs the wavefront reconstruction function that would otherwise require complex optical components. The eye's natural ability to integrate light signals from different directions and times allows it to reconstruct the wavefront from sequentially projected light-field components, eliminating the need for additional active optical elements in the projector
4Device complexity
If the image plane is fixed at the image source plane, then the device complexity is reduced, but the resolution is limited when focusing on virtual pixels away from the image source
Solution Approach 1:
The invention uses the spatial arrangement of multiple pinholes in a two-dimensional array to provide focusing capability for virtual pixels at different depths. By varying the spatial distribution and activation patterns of pinholes across the array, the system can project light-field components that converge at different virtual image planes, enabling focus adjustment without mechanical movement
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
The projector achieves higher effective resolution by aligning the focal plane with the image source, providing correct accommodation cues without additional varifocal mechanisms, and supports near-eye displays for virtual and augmented reality applications.
Implementation Method 1
an imaging optical element collimating the plurality of modulated light beams
Implementation Method 2
projection optics comprising a first projection element configured to project the modulated light beams such as to define an eye-box and to form projector pixel images of the pixel components at a projector image plane
Implementation Method 3
The imaging optical element is configured to shift the projector image plane to a shifted plane, between the first projection element and the eye-box where the projector pixel image coincides with the projector virtual pixel image
Data Source
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Figure 3a
AI summary
Light-field projector for projecting an image, comprising: a light-field image source (1) comprising an image generating device (20a, 20b), including a plurality of pixel components (15a-15d) generating a plurality of modulated light beams (111); an imaging optical element (70) projecting an image of the plurality of modulated light beams (111) to a light-source image plane (34); projection optics (2) configured to project the modulated light beams (111) such as to define an eye-box (121) and to form projector pixel images (16a-16d); the projection optics (2) further configured to form projector pixel images (16a-16d) at a projector image plane (115) and projector virtual pixel image (26a) at a shifted plane (114). The imaging optical element (70) is configured such that the position of the projector image plane (115) coincides with the position of the shifted plane (114).