Projection Apparatus Illumination Uniformity via Fly's Eye Integrator
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Solution Overview
Problem
Current projection apparatuses for head-mounted displays face challenges in achieving uniform energy intensity distribution of image beams, which affects visual quality and user experience in augmented reality and virtual reality applications.
Innovation Solution
A projection apparatus is designed with an illumination system that includes a diffusion device and a light uniform device, along with a collimating lens set and prism module, to ensure the image beam has a uniform energy intensity distribution on a stop, with peak and valley values configured to achieve high uniformity, reducing the energy intensity variation to less than 15% or 10%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional illumination systems are used in projection apparatus, then the structure is simple, but the energy intensity distribution outside the stop is non-uniform, affecting visual quality
Solution Approach 1:
The patent introduces a fly's eye integrator as an intermediary optical component between the illumination light source and the spatial light modulator. This integrator consists of an array of lenslets that redistribute the illumination light to achieve uniform energy intensity distribution at the stop, effectively mediating between the non-uniform light source and the requirement for uniform illumination.
Solution Approach 2:
The illumination system is segmented into multiple functional components: illumination light source, fly's eye integrator with lenslet array, spatial light modulator, and projection lens. The fly's eye integrator itself is segmented into multiple lenslets that work together to achieve uniform light distribution, breaking down the complex illumination task into manageable optical stages.
2Reliability
If the energy intensity distribution is made uniform using additional optical components, then visual quality improves, but the device complexity and number of components increase
Solution Approach 1:
The fly's eye integrator serves multiple functions simultaneously: it uniformizes the energy intensity distribution, controls the illumination angle, and directs light to the stop. This multi-functionality reduces the need for additional separate components, achieving reliable visual quality without proportionally increasing device complexity.
Solution Approach 2:
The patent combines the uniformization function and the direction control function into a single fly's eye integrator component. The lenslet array both redistributes light for uniformity and directs it toward the stop, merging multiple optical functions into one integrated element to minimize the total number of components.
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 solution ensures a uniform energy intensity distribution of the image beam on the stop, enhancing visual quality and user experience by minimizing variations in brightness, thereby improving the overall performance of head-mounted displays in augmented and virtual reality applications.
Implementation Method 1
The diffusion device is configured to allow the image beam to have an energy intensity distribution
Implementation Method 2
a total internal reflection surface positioned to internally reflect the light rays towards an asymmetric reflector surface
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A projection apparatus including an image device and an illumination system is provided. The image device is configured to convert an illumination beam into an image beam. The illumination system includes an illumination light source, a diffusion device and a light uniform device. The illumination light source provides the illumination beam. The illumination beam is transmitted to the image device through the diffusion device and the light uniform device sequentially. The image beam leaves the projection apparatus and converges at a stop. The stop is located outside the projection apparatus. The image beam on the stop has desirable uniformity of an energy intensity distribution.