Micro-Lens Array Laser Projection for High-Contrast Spot Fields
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Solution Overview
Problem
Existing laser projection modules for structured light and TOF technologies are complex, thick, and costly due to the use of collimating lenses and diffraction optical elements, and micro-lens array-based solutions do not optimize contrast effectively.
Innovation Solution
A laser projection module utilizing a micro-lens array with aspherical surfaces and specific working distances and focal lengths, configured to project spot and uniform light fields, with adjustable micro-lens arrays and illumination light sources to enhance contrast and reduce module thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a collimating lens and diffraction optical element (DOE) are used to project a laser spot array, then the projection function is achieved, but the device becomes complex and thick
Solution Approach 1:
The patent extracts and removes the collimating lens from the optical system. By using a VCSEL array that directly emits collimated light, the need for a separate collimating lens is eliminated, simplifying the overall structure and reducing device thickness while maintaining the laser spot array projection function
Solution Approach 2:
The patent merges the light source and collimation function into a single integrated VCSEL array module. The VCSELs inherently produce collimated light, combining what were previously separate components (light source + collimating lens) into one unified structure, thereby reducing system complexity and thickness
2Ease of manufacture
If a collimating lens and diffraction optical element (DOE) are used to project a laser spot array, then the projection function is achieved, but the cost increases
Solution Approach 1:
The patent removes the diffraction optical element (DOE) from the system by using a micro-lens array instead. This extraction eliminates the need for precise DOE fabrication and alignment, simplifying manufacturing processes and reducing production costs while maintaining the ability to project structured light patterns
Solution Approach 2:
The patent employs a micro-lens array that can be manufactured using cost-effective techniques such as photolithography and reflow processing. These micro-lens arrays can be produced in large quantities at low cost, making the overall system more economically viable compared to precision DOE-based solutions
3Length of stationary object
If a micro-lens array is used to generate structured light, then the device thickness is reduced, but the contrast of laser spot array is not optimized
Solution Approach 1:
The patent applies local quality optimization by designing the micro-lens array with specifically engineered focal lengths and pitch dimensions. Each micro-lens is configured with precise parameters to focus light into high-contrast spots, ensuring optimal spot array contrast while maintaining the thin form factor. The focal length and pitch are carefully selected to achieve the desired spot size and separation
Solution Approach 2:
The patent optimizes the contrast of the laser spot array by carefully selecting and adjusting key parameters including the focal length of micro-lenses, the pitch between micro-lenses, and the working distance. By changing these parameters within specific ranges, the system achieves high spot array contrast while maintaining a compact, thin structure
4Manufacturing precision
If the micro-lens array working distance is not optimized, then the structure is simple, but the spot array contrast is poor
Solution Approach 1:
The patent determines the optimal working distance between the micro-lens array and the light source by analyzing the relationship between working distance, focal length, and spot array contrast. By establishing specific working distance ranges based on optical parameters, the system achieves high contrast without requiring complex active control mechanisms, maintaining structural simplicity
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
Improves the contrast of laser spot arrays and enables efficient projection of both spot and uniform light fields, reducing module thickness and cost while maintaining performance.
Implementation Method 1
the first micro-lens array has a first working distance D1 relative to the illumination light source, and light from the illumination light source is modulated by the first micro-lens array to project a spot array light field on the target surface
Data Source
AI summary
A laser projection module includes an illumination light source and a micro-lens array. The micro-lens array includes a plurality of micro-lenses arranged at a first pitch P. In a working mode of projecting a spot array light field, a working distance D1 of the micro-lens array relative to the light source satisfies the following equation:D1=NP22λ+αfwhere N is a positive integer, preferably N≤5; λ is the wavelength of light from the light source; α is a coefficient, 0<α≤1; and f is a focal length of the micro-lens. By selecting and optimizing the coefficient α for the focal length of the micro-lens, light energy of the spot array light field generated with the corresponding working distance is focused onto smaller spots, and thus contrast of laser spot array is improved.