AR Light Projector Polarization Split-Recombine Layout
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Solution Overview
Problem
Existing augmented reality light projectors face challenges in efficiently utilizing unpolarized light sources, leading to inefficient power consumption and the need for compact, robust optical components that can withstand rough treatment.
Innovation Solution
A light projector design utilizing a beam splitter to split unpolarized light into two paths, each reflected and focused by angled mirrors, combined with a polarizing beam splitter to align and recombine light at the exit pupil, optimizing efficiency and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a linear polarisation filter is used to enable unpolarised light sources, then the projector can operate with unpolarised light, but around 50% of the incident light is rejected, reducing efficiency
Solution Approach 1:
The optical system is divided into two separate optical paths (first and second paths) that process different polarisation components of light independently. The beam splitter separates unpolarised light into these two paths, allowing each path to handle one polarisation component without rejecting the other, thereby eliminating the 50% light loss associated with single polarisation filtering.
Solution Approach 2:
A beam splitter is introduced as an intermediary component between the unpolarised light source and the optical arrangements. This beam splitter divides the unpolarised light into two separate paths based on polarisation, enabling both polarisation components to be utilized effectively rather than rejecting one component.
2Weight of moving object
If batteries are kept small and lightweight for wearable displays, then the headset is more comfortable and wearable, but battery resources are limited, requiring careful energy management
Solution Approach 1:
The invention converts what would be wasted light energy (the harmful aspect of using unpolarised light sources) into useful light output by utilizing both polarisation components through the two optical paths. This increases overall system efficiency, reducing power consumption and extending battery life without requiring larger or heavier batteries.
Solution Approach 2:
The system changes the operational parameters by accepting unpolarised light (rather than requiring linearly polarised light) and processing it through two separate optical paths with mirrors angled at 45 degrees. This parameter change enables more efficient light utilization, reducing the power consumption required for a given light output level.
3Strength
If optical components are made compact and robust for integration in headsets, then they can withstand rough treatment and are easier to integrate, but design flexibility may be reduced
Solution Approach 1:
The two optical arrangements are positioned asymmetrically with mirrors angled at 45 degrees relative to each other and to the beam splitter. This asymmetric configuration allows compact integration while maintaining the ability to process both polarisation components effectively, balancing robustness with design flexibility.
Solution Approach 2:
The optical paths are arranged in different spatial dimensions and orientations, with mirrors positioned at 45-degree angles to redirect light between paths. This three-dimensional arrangement enables compact integration of the two optical paths within a small volume while maintaining robustness for wearable applications.
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 design achieves high efficiency in using unpolarized light, minimizing power consumption and enabling a compact, robust projector suitable for augmented reality headsets.
Implementation Method 1
a beam splitter configured to receive unpolarised light from the image generator and to split it into a first path and a second path
Implementation Method 2
a first optical arrangement configured to receive light from the beam splitter in the first path so that light is reflected, focused and directed back towards the beam splitter; and a second optical arrangement configured to receive light from the beam splitter in the second path so that light is reflected, focused and directed back towards the beam splitter
Implementation Method 3
the beam splitter is configured to receive and combine light from the first and second optical arrangements so that the combined light, which is unpolarised, is provided to an exit pupil
Implementation Method 4
the first and second optical arrangements comprise first and second mirrors; wherein the beam splitter is configured to receive and combine light from the first and second optical arrangements
Data Source
AI summary
A light projector for an augmented reality headset is disclosed. First and second optical arrangements receive light from a polarising beam splitter so that light is reflected, focused and directed back towards the polarising beam splitter from each optical arrangement. The first and second optical arrangements comprise first and second mirrors and first and second quarter-wave plates. The polarising beam splitter receives and combines light from the first and second optical arrangements so that the combined light, which is unpolarised, is provided to an exit pupil. The first and second optical arrangements are angled relative to one another so that the image from the first optical arrangement is aligned with the image from the second optical arrangement.