Rotating Mirror Segmentation for Near-Range Laser Radar Detection
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Solution Overview
Problem
Laser radar apparatuses with aligned emission and reflection optical axes face challenges in detecting objects at very near distances due to reduced light reception, as the proportion of reflected light passing through the hole in the reflection mirror increases, leading to minimal incident-light amounts and potential undetection of near objects.
Innovation Solution
The laser radar apparatus incorporates a rotating mirror with a flat central reflective surface and a sloped peripheral surface, spreading outgoing laser light to improve light reception at near distances by ensuring sufficient light intensity is maintained for detection, even when objects are close, by diffusing the light to cover a wider area of the rotating mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emission optical axis and reflection optical axis are aligned to improve light reception efficiency, then light reception capability is improved, but light reception amount at very near distances becomes minimal due to reflected light passing through the hole in the reflection mirror
Solution Approach 1:
The reflective surface of the rotating mirror is divided into two distinct regions: a flat reflective surface for long-distance detection and a sloped reflective surface for near-distance detection. This segmentation allows each region to optimize light reflection for its specific distance range, resolving the contradiction between overall light reception capability and near-distance light reception amount.
Solution Approach 2:
Different regions of the rotating mirror are assigned different reflective properties: the flat reflective surface maintains parallel light transmission for distant objects, while the sloped reflective surface diffuses light to the periphery for near objects. This local differentiation in reflective quality enables the system to handle both far and near distance detection effectively.
2Length of stationary object
If laser light is emitted with small divergence angle to detect distant objects, then distant object detection is improved, but light spreads excessively over long distances causing low reflected light intensity
Solution Approach 1:
The reflective surface is segmented into flat and sloped regions that handle different distance ranges differently. The flat surface preserves the small divergence angle for distant objects, while the sloped surface compensates for light spreading by diffusing light to the periphery, maintaining sufficient intensity for near-object detection.
Solution Approach 2:
The sloped reflective surface redirects light in a different spatial dimension by diffusing it to the periphery of the optical axis. This dimensional redistribution of light paths compensates for the intensity loss due to long-distance spreading, ensuring sufficient light reaches the detector.
3Measurement precision
If detecting unit performs signal correction to enable uniform detection from long to short distances, then detection uniformity is improved, but fog and low reflectivity objects are not detected
Solution Approach 1:
Instead of applying uniform signal correction across all distances, the system segments the optical path into far-distance and near-distance components using the flat and sloped reflective surfaces. This allows the system to maintain appropriate signal levels for both ranges without needing aggressive correction that would mask low-reflectivity targets like fog.
4Length of stationary object
If the proportion of reflected light passing through the hole in the reflection mirror increases for near distance detection, then near object detection is improved, but light loss increases leading to minimal incident-light amounts
Solution Approach 1:
The reflective surface is segmented so that the sloped region specifically handles near-distance reflection. This segmentation ensures that light for near objects is efficiently directed through the hole in the reflection mirror without being lost, as the sloped surface optimizes the reflection angle to maximize light transmission through the hole.
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 light reception capability for near distances, allowing for effective detection of objects at varying distances from far to near, with improved light reception amounts and reduced light loss, enabling reliable detection without the need for signal correction at short distances.
Implementation Method 1
a rotating mirror that reflects the outgoing laser light passed through the hole in the reflection mirror for light reception and irradiates the outgoing laser light towards a target area to be targeted, and receives returning laser light reflected from the target area and returned and reflects the returning laser light towards a direction of the reflection mirror for light reception
Implementation Method 2
the rotating mirror includes a flat reflective surface that forms a flat planar shape in a center portion of a reflective area that reflects the outgoing laser light, and a sloped reflective surface in a peripheral portion of the center portion of the reflective area, the sloped reflective surface spreading the outgoing laser light incident on the peripheral portion to a periphery of an optical axis of the outgoing laser light emitted from the flat reflective surface
Data Source
AI summary
A laser radar apparatus that includes a rotating mirror is provided. The rotating mirror has a reflective area that reflects outgoing laser light. A flat reflective surface that forms a flat planar shape is formed in a center portion of the reflective area. A sloped reflective surface is formed in a peripheral portion of the center portion of the reflective area, the sloped reflective surface spreading the outgoing laser light incident on the peripheral portion to a periphery of an optical axis of outgoing laser light emitted from the flat reflective surface.