Laser Radar Fast Axis Alignment for Energy Density
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Solution Overview
Problem
Laser radars with increased resolution in detection areas face reduced frame rates due to increased energy density loss in line beams as distance increases, making it difficult to detect objects at longer distances effectively.
Innovation Solution
A laser radar system with a laser diode disposed such that its fast axis aligns with the short side direction of the line beam, using an optical system to maintain beam spread angle close to parallel, thereby minimizing energy density loss and enhancing detection range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If scanning is performed with an elongated line beam to cover the measurement target area, then the detection area is improved, but the energy density of the line beam decreases as the distance to the measurement target area increases
Solution Approach 1:
The patent applies asymmetry by orienting the laser diode such that its fast axis (which has smaller natural divergence) aligns with the long side direction of the line beam, while the slow axis (with larger natural divergence) aligns with the short side direction. This asymmetric orientation allows the beam spread to be naturally controlled, maintaining higher energy density in the long side direction while still covering the required detection area through the line beam configuration.
Solution Approach 2:
The patent changes the beam spread angle parameter by utilizing the inherent difference between fast axis and slow axis divergence characteristics of the laser diode. By controlling the beam spread angle in the short side direction to be smaller than in the long side direction, the system maintains energy density while expanding the detection area. The optical system parameters are optimized to achieve the desired beam shape and spread characteristics.
2Measurement precision
If resolution at measurement positions is increased, then detection accuracy is improved, but frame rate for acquiring information is significantly reduced
Solution Approach 1:
The patent transitions from point-by-point scanning to line beam scanning, effectively moving from one-dimensional scanning to two-dimensional coverage in a single scan line. This dimensional change allows the system to maintain high detection accuracy across the entire measurement area while significantly improving the frame rate, as the entire line is measured simultaneously rather than sequentially.
3Length of stationary object
If the line beam is projected to detect objects at longer distances, then detection range is improved, but energy density in the short side direction decreases
Solution Approach 1:
The patent utilizes the asymmetric beam spread characteristics of the laser diode, where the fast axis divergence is naturally smaller than the slow axis divergence. By orienting the fast axis along the long side direction and the slow axis along the short side direction, the system achieves better energy density maintenance in the short side direction, enabling effective detection at longer distances while preserving beam energy concentration.
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 system effectively inhibits energy density decrease in the short side direction of the line beam, allowing for accurate detection of objects at longer distances while maintaining high detection accuracy and efficiency.
Implementation Method 1
a laser diode; an optical system configured to shape laser light emitted from the laser diode
Implementation Method 2
the beam spread angle in the short side direction of the line beam can be set such that the line beam is closer to parallel light
Data Source
AI summary
A laser radar includes: a light source including a laser diode; an optical system configured to shape laser light emitted from the laser diode, into a line beam that is long in one direction, and project the line beam to a target area; and a scanner configured to perform scanning with the line beam in a short side direction of the line beam. The laser diode is disposed such that a fast axis of the laser diode extends along a direction corresponding to the short side direction of the line beam.