LiDAR Deflector Beam Divergence Control
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Solution Overview
Problem
LiDAR systems face performance deterioration when measuring long distances due to the shifting light receiving optical path caused by the drive mirror's movement, leading to reduced light reception and measurement accuracy.
Innovation Solution
An optical apparatus with a deflector and controller that adjusts the illumination light's divergence angles and speeds across different sections, ensuring consistent light reception regardless of the drive mirror's state, using a multistack multimode laser diode and a bifurcation to manage the illumination and light receiving paths effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the illumination light is emitted to a long-distance object, then the measurement range is extended, but the drive mirror moves significantly during the light travel time causing the light receiving optical path to shift from the light receiving element
Solution Approach 1:
The patent applies dynamics by making the illumination light beam dynamic in its divergence characteristics. The beam divergence is adjusted based on the distance to the target object, allowing the beam to adapt its spread pattern. This dynamic adjustment ensures that even when the drive mirror moves during long-distance light travel, the reflected light remains within the light receiving element's acceptance angle, maintaining measurement precision while extending measurement range.
Solution Approach 2:
The patent changes the divergence angle parameter of the illumination light based on target distance. By controlling the beam divergence to be smaller for long-distance targets and larger for short-distance targets, the system optimizes the light path geometry. This parameter change ensures that the reflected light from distant objects, which take longer to return, still falls within the light receiving element's field of view despite drive mirror movement, thereby resolving the contradiction between extended range and maintained precision.
2Speed
If the drive mirror moves at high speed to scan objects quickly, then the scanning speed increases, but the light receiving optical path shifts from the light receiving element reducing measurement accuracy
Solution Approach 1:
The system dynamically adjusts the illumination beam divergence based on the drive mirror's scanning speed and the target distance. When scanning speed increases, the beam divergence is reduced to create a narrower, more focused beam. This dynamic adaptation ensures that even with faster mirror movement, the reflected light path remains aligned with the light receiving element, maintaining measurement accuracy while enabling higher scanning speeds.
Solution Approach 2:
The patent modifies the beam divergence parameter in response to scanning speed changes. By controlling the illumination beam to have appropriate divergence characteristics matched to the scanning conditions, the system ensures that the light path geometry compensates for the drive mirror's movement. This parameter adjustment maintains the relationship between the illuminated area and the light receiving element's field of view, resolving the trade-off between scanning speed and measurement precision.
3Measurement precision
If a narrow beam divergence is used to maintain precise light reception, then the light receiving accuracy improves, but the illumination coverage area decreases reducing the ability to detect objects at various distances
Solution Approach 1:
The patent implements dynamic beam divergence control where the illumination beam's spread angle is adjusted according to the distance to the target object. For distant objects, the beam divergence is reduced to maintain precise light reception and measurement accuracy. For closer objects, the beam divergence is increased to provide sufficient illumination coverage. This dynamic adaptation allows the system to maintain both accurate light reception and adequate illumination coverage across varying distances.
Solution Approach 2:
The system changes the beam divergence parameter based on target distance measurements or scanning position information. By controlling the illumination beam to have distance-appropriate divergence, the patent ensures that the illuminated area matches the light receiving element's field of view at each distance. This parameter adjustment resolves the contradiction by making the beam width adaptive rather than fixed, allowing precise reception for distant targets while providing sufficient coverage for nearer targets.
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
Enables accurate detection of objects from short to long distances without light shielding, maintaining measurement performance across varying deflection angles and frequencies of the drive mirror.
Implementation Method 1
a deflector configured to deflect illumination light from a light source unit to scan an object and to deflect reflected light from the object
Implementation Method 2
A first divergence angle of the illumination light in a first cross section is larger than a second divergence angle in a second cross section orthogonal to the first section
Data Source
AI summary
An optical apparatus includes a deflector configured to deflect illumination light from a light source unit to scan an object and to deflect reflected light from the object, and a controller configured to control the deflector. A first divergence angle of the illumination light in a first cross section is larger than a second divergence angle in a second cross section orthogonal to the first section. The controller controls the deflector so that the illumination light moves in the first cross section at a first speed and moves in the second cross section at a second speed higher than the first speed.