Prism Beam Expander With Partial-Reflection Beam Homogenization
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Solution Overview
Problem
Optical beam expanders often fail to achieve substantial beam expansion in one dimension while ensuring high homogenization of the expanded beam, which is crucial for applications like projection systems.
Innovation Solution
A trapezoidal block of transparent material with parallel, partially-reflecting layers is used, where the beam is internally reflected and split multiple times, resulting in an expanded and homogenized output beam with a width at least twice the input beam width, utilizing anti-reflective and reflective coatings to optimize light transmission and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional beam expanders are used, then beam expansion is achieved, but homogenization of the expanded beam is insufficient
Solution Approach 1:
The beam expansion process is segmented into multiple discrete reflection events. The input beam is split into multiple separate beams through sequential reflections from partially-reflecting layers, with each reflection creating a distinct beam path. This segmentation allows independent control of each beam's trajectory and intensity, enabling precise homogenization of the final expanded beam while achieving substantial width expansion.
2Area of moving object
If multiple beam splitting is implemented, then beam expansion increases, but device complexity increases
Solution Approach 1:
Multiple beam splitting and reflection functions are merged into a single integrated transparent block. The block contains multiple partially-reflecting layers embedded within it, all working together to perform beam splitting, steering, and homogenization in one compact component. This merging eliminates the need for multiple separate optical elements and alignment mechanisms, reducing device complexity while maintaining high beam expansion capability.
Solution Approach 2:
The transparent block serves multiple functions simultaneously: it acts as a beam splitter, beam steerer, homogenizer, and structural support element. The partially-reflecting layers within the block perform both beam division and directional control, while the block's geometry provides mechanical stability and optical path definition. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure.
3Area of moving object
If internal reflection is used for beam expansion, then beam width increases, but light loss increases
Solution Approach 1:
Instead of using total internal reflection which would cause complete light redirection, the patent employs partial reflection at each interface. The partially-reflecting layers are designed to reflect only a portion of the incident light while allowing the remainder to transmit through. This partial action approach ensures that sufficient light reaches the final output beam while still achieving the necessary beam expansion through multiple reflection events, thereby minimizing overall light loss.
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 effectively expands the input beam in one dimension while achieving high homogenization of the output beam, suitable for applications such as virtual and augmented reality systems and other image projection needs.
Implementation Method 1
One or more planar, partially-reflecting layers extend within the block between the third and fourth faces
Implementation Method 2
the first and second faces are configured to reflect internally rays of light that impinge on the first and second faces
Data Source
AI summary
An optical component includes a block of a transparent material, having a trapezoidal cross-section defined by first and second parallel, rectangular faces on mutually-opposing sides of the block and third and fourth faces oriented diagonally at opposing ends of the first and second faces. One or more planar, partially-reflecting layers extend within the block between the third and fourth faces in an orientation parallel to the first and second faces.