Optical Module Diffraction Element Resolution Efficiency
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Solution Overview
Problem
Increasing the number of light emitting elements in optical modules to improve resolution leads to increased laser oscillation threshold current and decreased electro-optical conversion efficiency, while also limiting the arrangement of elements with narrow intervals and making multipath correction difficult as the number of spots increases.
Innovation Solution
An optical module with a light emission unit featuring light emitting elements arranged in a quadrangular structure, where the distance between elements in one direction is 'a' and in a perpendicular direction is 'b', utilizing a diffraction element that diffracts light into 'n' directions, with specific angle and diffraction angle configurations, and including a switching unit to adjust light emission patterns, and a light detection unit to detect reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light emitting elements is increased to improve resolution, then resolution is improved, but laser oscillation threshold current increases and electro-optical conversion efficiency decreases
Solution Approach 1:
The patent divides the light emission function into two parts: a small number of light emitting elements generate light, and a diffraction element divides this light into multiple beams. This segmentation allows achieving multiple spot coverage without proportionally increasing the number of light emitting elements, thereby maintaining electro-optical conversion efficiency while improving resolution through increased spot count.
Solution Approach 2:
The diffraction element acts as an intermediary between the light emitting elements and the target. It takes light from a small number of elements and transforms it into multiple diffracted beams, effectively multiplying the light distribution capability without requiring proportional increases in light emitting elements, thus resolving the contradiction between resolution and efficiency.
2Measurement precision
If the number of light emitting elements is increased to improve resolution, then resolution is improved, but the area of the light emission unit increases
Solution Approach 1:
The patent segments the light generation and light distribution functions. A compact light emission unit with minimal area contains only the necessary light emitting elements, while the diffraction element creates multiple spots spatially distributed on the target. This allows high resolution through multiple spots without increasing the physical area of the light emission unit.
Solution Approach 2:
Instead of increasing resolution by adding more elements in the same plane (two-dimensional expansion), the patent uses the diffraction element to create spots in different spatial directions and angles. This transitions from planar expansion to three-dimensional light distribution, achieving multiple spots without increasing the emission unit area.
3Measurement precision
If the number of spots increases to improve resolution, then resolution is improved, but multipath correction becomes more difficult
Solution Approach 1:
The patent segments the light paths through diffraction, creating distinct spatially separated beams with specific angle relationships. This segmentation of light paths makes it easier to distinguish direct reflection from multipath reflections, as each diffracted order follows a predictable geometric path, simplifying the identification and correction of multipath errors.
Solution Approach 2:
The diffraction element serves multiple functions simultaneously: it increases the number of spots for improved resolution, maintains regular spacing for uniform coverage, and creates geometrically predictable light paths that facilitate multipath correction. This multi-functionality resolves the contradiction by making the system that generates multiple spots also inherently more manageable for correction purposes.
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
This configuration enhances resolution while reducing the number of light emitting elements, maintains light intensity, and facilitates effective multipath correction by increasing the number of spots with regular spacing, thereby improving ranging accuracy and resolution.
Implementation Method 1
a diffraction element that diffracts a light beam emitted from each of the light emitting elements and separates the light beam into a plurality of light beams
Implementation Method 2
an optical element that converts the light beam emitted from the light emitting element into a substantially parallel light beam or a light beam having a predetermined angular width
Implementation Method 3
a light detection unit that detects reflected light from a target with respect to the light beam
Data Source
AI summary
To improve resolution while suppressing the number of light emitting elements arranged in an optical module.The optical module is provided with an optical element that converts a light beam emitted from the light emitting element into a substantially parallel light beam or a light beam having a predetermined angular width, and a diffraction element that diffracts the light beam to separate into a plurality of light beams. The diffraction element generates diffracted lights in n direction, and an angle θx formed between one diffraction direction and a side in a direction in which the light emitting element is arranged satisfies tan−1 (b/3a). A diffraction angle φx of the diffracted light satisfies m·sgrt((3φa){circumflex over ( )}2+φb{circumflex over ( )}2)/(2(2n+1)). Note that, φa and φb are angular differences of two light beams caused by inter-light emission distances a and b. Furthermore, n is a natural number, and m is a natural number excluding an integral multiple of 2n+1.