Diffractive Optical Module with Micron Structures for Laser Projection
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Solution Overview
Problem
Current surface light source projection devices for time-of-flight ranging sensing face challenges with heat accumulation and degradation when using high-energy lasers, particularly short-wavelength lasers, due to polymer materials used in diffusers and diffractive elements, limiting their applicability to short and medium distances and posing safety risks.
Innovation Solution
A surface light source projection device incorporating a diffractive optical module with two micron diffractive layers, featuring micron structures with outer diameters between 5 and 200 times the incident wavelength, which generates a high-density dot matrix diffraction pattern with low zero-order diffraction intensity, made from transparent crystal or glass materials resistant to heat and degradation, enabling long-distance sensing and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer materials are used in diffusers and diffractive elements, then the device can be manufactured easily and cost-effectively, but heat accumulation and material degradation occur when using high-energy lasers
Solution Approach 1:
The patent uses glass materials with microlens arrays and diffractive structures integrated into a single composite optical element. This composite structure combines the optical functionality of diffractive elements with the structural stability of glass, eliminating the heat accumulation and degradation issues associated with polymer materials while maintaining manufacturability through precision molding techniques.
2Length of moving object
If collimated light systems with multiple lenses are used, then long-distance sensing is achieved, but the device thickness increases
Solution Approach 1:
The patent integrates multiple optical functions (collimation, diffraction, and focusing) into a single nested structure where the diffractive optical element is embedded within a glass substrate containing microlens arrays. This nesting eliminates the need for separate lens assemblies, achieving long-distance projection capability while maintaining a thin device profile.
Solution Approach 2:
The patent transitions from a multi-component three-dimensional lens system to a planar two-dimensional diffractive optical element with encoded phase information. By encoding optical path differences in the lateral dimensions of the diffractive pattern rather than using physical lens thickness, long-distance projection is achieved without increasing device thickness.
3Adaptability or versatility
If diffusers are used to increase angular range, then field of view coverage is improved, but light polarization and directivity are destroyed
Solution Approach 1:
The patent employs microlens arrays with varying focal lengths and orientations at different local positions within the glass substrate. Each microlens group is optimized for specific angular directions, providing broad field of view coverage while maintaining controlled light propagation paths that preserve polarization states and directivity through structured optical guidance rather than random diffusion.
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 provides a stable and effective beam diffusing system that maintains light polarization and directivity, suitable for long-term irradiation and long-distance sensing, while preventing thermal accumulation and degradation, thus enhancing the safety and applicability of the device in various environments.
Implementation Method 1
the diffracted light generated by the beam passing through the diffractive optical module can realize a diffraction pattern with high-density dot matrix and low zero-order diffraction intensity
Implementation Method 2
made from transparent crystal or glass materials resistant to heat and degradation, enabling long-distance sensing and stability
Data Source
AI summary
The present invention provides a surface light source projection device, which includes a light emitting module and a diffractive optical module. Wherein, the diffractive optical module has two micron diffractive layers, the micron diffractive layers include a plurality of micron structures, and the shape of the micron structures is set to be cone, disc or any combination of the above. The micron structures have an outer diameter, and the outer diameter of the micron structures is between 5 times and 200 times of the incident wavelength of the light beam output from the light emitting module. Thereby, the surface light source projection device capable of enduring heat accumulation generated after continuous irradiation of high-energy laser is provided to facilitate long-term irradiation and long-distance sensing.