Piezoelectric Light Homogenizing Element for Speckle Reduction
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Solution Overview
Problem
Existing solutions for reducing speckle in laser light sources, such as wavelength and angular diversity, either increase the volume and weight of the mechanism or lead to instability, and are not applicable to wearable displays, making it challenging to achieve miniaturization while maintaining image quality.
Innovation Solution
A light homogenizing element with a piezoelectric film, driving electrode, and light diffusion microstructures that dynamically deform the light incident surface, changing the light path deflection direction over time to reduce speckle contrast and improve brightness uniformity, while maintaining a small volume and low vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wavelength diversity technique is used to reduce speckle, then speckle contrast is reduced, but volume and weight of the mechanism increase
Solution Approach 1:
The patent employs a movable diffuser that can dynamically change its position or orientation to achieve angular diversity. This dynamic mechanism allows the system to reduce speckle contrast by varying the angle of light propagation without requiring multiple fixed optical paths, thereby reducing the overall volume compared to static wavelength diversity approaches that would need multiple light sources or filters.
Solution Approach 2:
The patent changes the angular parameter of light propagation by moving the diffuser to different positions or orientations. This parameter change achieves speckle reduction through angular diversity while maintaining a compact design, as it uses a single light source with variable angle output rather than multiple sources or broadband sources that would increase volume.
2Object-affected harmful factors
If angular diversity technique is used to reduce speckle, then brightness uniformity is improved, but vibration increases and stability decreases
Solution Approach 1:
The patent implements periodic motion of the diffuser to achieve speckle reduction. By oscillating or rotating the diffuser at controlled frequencies, the system creates time-varying angular diversity that averages out speckle patterns. This periodic action maintains brightness uniformity while the controlled nature of the motion minimizes excessive vibration and maintains light path stability compared to random or uncontrolled movements.
3Volume of moving object
If miniaturization is achieved in wearable displays, then device size is reduced, but speckle suppression capability is compromised
Solution Approach 1:
The patent uses a thin-film movable diffuser that can be integrated into compact wearable display structures. This thin-film approach allows the diffuser to be positioned close to the light source and requires minimal space, enabling miniaturization while maintaining the angular diversity function needed for speckle suppression. The flexible nature of the thin film allows for precise positioning control in a small volume.
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
Effectively reduces speckle contrast and improves brightness uniformity in laser light sources, suitable for miniaturized applications like wearable displays, with fast response and silent operation.
Implementation Method 1
The piezoelectric film is located on the carrier layer. The driving electrode is located on the carrier layer and drives the piezoelectric film, where the driving electrode applies driving voltage to the piezoelectric film, such that the piezoelectric film is stretched and deformed
Implementation Method 2
The multiple light diffusion microstructures are provided on the at least one diffusion surface, and projections of the multiple light diffusion microstructures on the light-transmitting layer are located in the light passing region
Data Source
AI summary
A light homogenizing element includes a light incident surface and at least one diffusion surface, including: a first substrate, a carrier layer, a piezoelectric film, a driving electrode, a light-transmitting layer, and multiple light diffusion microstructures. The first substrate includes a first surface and a second surface opposite to each other. The carrier layer is located on the first surface of the first substrate and includes a light passing region penetrating the carrier layer, and includes a protruding structure enclosing the light passing region. The light-transmitting layer is provided overlapping on the protruding structure, and the surface of the light-transmitting layer covering the light passing region is the light incident surface. The multiple light diffusion microstructures are provided on the at least one diffusion surface, and projections of the multiple light diffusion microstructures on the light-transmitting layer are located in the light passing region.