Holographic HMD Display With SLM Re-Imaging for Close-Range Depth Cues
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Solution Overview
Problem
Existing augmented reality displays based on binocular disparity struggle with displaying three-dimensional images at close range, leading to poor usability and difficulty in interacting with multiple focal planes, as they fail to provide depth cues and natural interaction with projected images.
Innovation Solution
A Head Mounted Display (HMD) system projects a Computer Generated Hologram (CGH) image via an optical element near the viewer's eye, allowing simultaneous viewing of the real world and holographic images, using a Spatial Light Modulator (SLM) to project coherent light and re-image the holographic image at various locations, adjusting focus and orientation to maintain image stability and depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If binocular disparity is used to display three-dimensional images, then depth perception is provided, but images at close range cannot be displayed properly and multiple focal planes cannot be interacted with naturally
Solution Approach 1:
The patent changes the fundamental parameter of image projection from binocular disparity (stereoscopic) to true holographic optical reconstruction. This enables the display of multiple focal planes at various distances including close range, allowing natural interaction and proper depth perception simultaneously by reconstructing the actual light field rather than simulating it through disparity
2Device complexity
If a fixed focal plane is used in augmented reality displays, then device complexity is reduced, but depth resolution variations are easily recognized and usability deteriorates
Solution Approach 1:
The patent implements a dynamic holographic display system that can adjust and reconstruct multiple focal planes at different distances. The optical element and spatial light modulator work together to dynamically shift focus between near and far objects, providing continuous depth resolution adjustment that maintains high usability while managing complexity through integrated optical design
3Ease of operation
If holographic images are displayed at close range, then natural interaction and depth cues are provided, but optical element design and image projection complexity increase
Solution Approach 1:
The patent employs a spatial light modulator that serves multiple functions: it generates the holographic pattern, controls the focal plane positioning, and enables image redirection to apparent locations beyond the physical optical element. This multi-functionality allows close range holographic display with natural interaction while managing complexity by consolidating control mechanisms into a single programmable device
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
Enables natural interaction with holographic images by providing depth cues and stable projection of holograms at close range, enhancing usability and interaction capabilities.
Implementation Method 1
producing a holographic image at a first location by projecting coherent light onto the SLM
Implementation Method 2
The term 'holographic image' is used in the present specification and claims to mean an 'interference based holographic image'
Implementation Method 3
re-imaging the holographic image from the first location to form a holographic image in front of an eye of a viewer wearing the HMD
Implementation Method 4
The present invention, in some embodiments thereof, relates to a display for projecting a Computer Generated Hologram (CGH) image to a viewer via an optical element close to the viewer's eye or eyes
Data Source
AI summary
A method of displaying a Computer Generated Holographic (CGH) image by a display, including setting pixel values of a Spatial Light Modulator (SLM) included in a Head Mounted Display (HMD), producing a interference based holographic image at a first location by projecting coherent light onto the SLM, and re-imaging the holographic image from the first location to form a holographic image in front of an eye of a viewer wearing the HMD. Related apparatus and methods are also described.