Light Source Unit Reducing Interference Fringes via Microlens Array
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Solution Overview
Problem
Conventional light source units for projectors, particularly those using laser diodes, suffer from interference fringes that deteriorate the quality of projection images, and existing solutions are complex and difficult to produce.
Innovation Solution
A light source unit comprising a plurality of semiconductor laser beam emitting elements, a microlens array with differently characterized microlenses, and collimator lenses that collect and superpose laser beams to reduce interference fringes by varying lens characteristics and orientation, making the system simpler and more efficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If laser diodes are used as light sources in projectors, then the light source unit can be made small in size and achieve high intensity, but interference fringes are generated that deteriorate the quality of the projection image
Solution Approach 1:
The invention divides the light source into multiple laser diodes arranged in an array, with each laser diode emitting laser beams that are processed by corresponding microlenses. This segmentation allows the system to maintain compact size while reducing interference fringes through the combined effect of multiple light sources with different optical paths
Solution Approach 2:
The invention applies different lens characteristics to microlenses at different positions in the array. Specifically, microlenses have varying focal lengths or lens shapes tailored to their local position, which modifies the optical path of laser beams from each laser diode differently, thereby reducing the visibility of interference fringes while maintaining overall system compactness
2Object-affected harmful factors
If a wavefront dividing device, polarization rotating device, and wavefront combining device are used to reduce interference fringes, then the quality of projection image is improved, but the light source unit becomes complex and difficult to produce
Solution Approach 1:
The invention merges the functions of wavefront division, polarization manipulation, and wavefront combination into a single integrated microlens array structure. Each microlens simultaneously performs wavefront shaping and directional control, eliminating the need for separate dividing devices, polarization rotating devices, and combining devices, thus simplifying the overall system while maintaining effectiveness in reducing interference fringes
Solution Approach 2:
The microlens array serves as an intermediary element that directly processes the laser beams from each laser diode. By positioning microlenses immediately adjacent to each laser diode, the system achieves wavefront control and interference reduction without requiring complex intermediate optical components, thereby simplifying the light source unit construction
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 reduces the visibility of interference fringes, enhancing the quality of projection images while maintaining a simple and cost-effective construction suitable for projectors.
Implementation Method 1
a microlens array which includes a plurality of microlenses which are arranged planarly so that optical axes thereof are parallel to one another and which make uniform light beams emitted from the light sources individually
Implementation Method 2
a collective lens which collects the light beams from the light sources which are made uniform when they pass through the microlens array in such a way that the light beams are irradiated on a predetermined surface
Data Source
AI summary
A light source unit includes a plurality of light sources that light source elements which emit laser beams and collimator lenses which collect the laser beams emitted from the light source elements are combined therein. Pencils of light emitted from the light source elements are made to be collected in different collecting degrees between the light sources respectively.