Diffractive Optical Element Phase Pattern for Uniform Irradiation
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Solution Overview
Problem
Diffractive optical elements struggle to achieve uniform intensity distribution over a wide field of view due to non-overlapping diffracted light beams, which is crucial for applications like LiDAR and projectors, as existing designs fail to effectively control the angular separation and divergence of diffracted light beams.
Innovation Solution
A diffractive optical element with a phase pattern designed to ensure the angular separation between diffracted light beams is smaller than the divergence angle, and the period length is optimized to allow for overlapping diffracted light beams without gaps, using specific mathematical conditions to maintain uniform intensity distribution across a wide field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the diffractive optical element uses conventional designs without specific angular separation control, then the device complexity is reduced, but the intensity distribution uniformity deteriorates
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships for the period length P and phase pattern that control the angular separation between diffracted light beams. The period length is designed to satisfy P = mλ/Z where m is an integer, and the phase pattern is designed with specific functional forms that ensure angular separation Δθ is within the divergence angle range. These parameter optimizations enable uniform intensity distribution without requiring complex additional optical components.
2Manufacturing precision
If the diffractive optical element uses larger period length to reduce diffraction angle, then the field of view is reduced, but the intensity distribution uniformity is improved
Solution Approach 1:
The patent resolves this contradiction by optimizing the period length P to satisfy specific mathematical conditions: P = mλ/Z where m is an integer between 1 and N, λ is wavelength, and Z is distance to projection plane. This optimized period length enables the angular separation between adjacent diffracted beams to be controlled within the divergence angle range while maintaining a wide field of view. The phase pattern is simultaneously optimized with functional forms that ensure uniform intensity distribution across the entire projection area.
Solution Approach 2:
The patent employs dynamic optimization by adjusting both the period length and phase pattern parameters based on the specific application requirements. The period length P and phase pattern parameters can be dynamically selected from ranges that satisfy the mathematical conditions, allowing the system to adapt to different wavelengths, projection distances, and field of view requirements while maintaining uniform intensity distribution.
3Ease of manufacture
If the diffractive optical element uses conventional phase patterns, then the ease of manufacture is improved, but the angular separation control deteriorates
Solution Approach 1:
The patent achieves both ease of manufacture and precise angular separation control by using conventional phase pattern fabrication methods with optimized parameters. The phase pattern is designed with specific functional forms (e.g., quadratic phase distributions) that can be manufactured using standard diffractive optical element fabrication techniques. The key optimization lies in selecting specific parameter values for the period length P and phase pattern coefficients that ensure angular separation Δθ satisfies the uniformity condition, while remaining compatible with existing manufacturing processes.
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 ensures uniform irradiation over a wide field of view by optimizing the period length and phase pattern of the diffractive optical element, allowing for efficient light projection and reducing the influence of zero-order light, thereby enhancing the performance of sensing and projection systems.
Implementation Method 1
Diffractive optical elements disperse incident light in various directions, with various distribution patterns, by making use of the phenomenon of light diffraction
Data Source
AI summary
A diffractive optical element includes a unit structure periodically arranged in a first direction and configured to diffract incident light in the first direction. The diffractive optical element has a phase pattern designed such that an angular separation between an outermost diffracted light beam and a second-outermost diffracted light beam along the first direction is smaller than the divergence angle of the incident light.