Lidar Receiver Wedge Depth of Field for Near Far Focus
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Solution Overview
Problem
Lidar systems face challenges in maintaining focus for both near and far targets due to the blurring effect when light pulses are scattered, as the reflection often extends beyond the focal point of the detector, leading to depth of field issues.
Innovation Solution
The implementation of a receiver with a lens and photodetectors arranged in a nonparallel configuration, where the detector plane is tilted with respect to the lens plane, creating a wedge-shaped depth of field that allows for focused detection of light pulses from both nearby and distant targets, optimizing resolution for specific distances and heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a parallel configuration of lens and detector planes is used, then the system structure is simple, but the depth of field is limited and cannot maintain focus for both near and far targets
Solution Approach 1:
The patent applies asymmetry by tilting the detector plane relative to the lens plane, creating a non-parallel configuration. This asymmetric arrangement generates a wedge-shaped depth of field that extends from near to far targets, allowing the system to maintain focus across a broader depth range without adding complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent introduces a new dimension to the detector arrangement by tilting the detector plane at an angle θ relative to the lens plane. This angular dimension transforms the traditional parallel planar detection into a wedge-shaped volume, enabling the system to capture light from targets at different distances simultaneously while maintaining optical resolution.
2Measurement precision
If the detector plane is tilted to create a wedge shaped depth of field, then focus is maintained for both near and far targets, but the manufacturing and alignment complexity increases
Solution Approach 1:
The patent changes the geometric parameter of the detector plane orientation from parallel (0 degrees) to a tilted configuration at angle θ. This parameter change creates a wedge-shaped depth of field that maintains focus for both near and far targets. The design optimizes this angle to balance depth of field coverage with manufacturing feasibility, avoiding excessive complexity while achieving the desired optical performance.
3Area of stationary object
If the light pulses are directed at different angles to scan the field of regard, then the coverage area is increased, but the depth of field issues worsen due to varying focal points
Solution Approach 1:
The tilted detector plane configuration provides universal focus capability across multiple angles and distances. By creating a wedge-shaped depth of field, the system can simultaneously maintain focus for light pulses directed at different angles to scan the field of regard, eliminating the need for angle-specific focal adjustments and enabling consistent measurement precision across the entire coverage area.
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 improves the optical resolution in lidar systems by ensuring that both nearby and far targets remain in focus, enhancing the accuracy of distance measurements and object detection within a range.
Implementation Method 1
The receiver includes a lens having a lens plane, where the lens is configured to focus the return light pulse
Implementation Method 2
the lens is configured to focus the return light pulse and one or more photodetectors arranged on a detector plane behind the lens
Implementation Method 3
one or more photodetectors arranged on a detector plane behind the lens, where the detector plane is nonparallel to the lens plane
Data Source
AI summary
To solve depth of field issues when scanning, transmitting, and receiving light pulses in a lidar system, a receiver in the lidar system may include a lens having a lens plane in front of one or several photodetectors arranged on a detector plane. The lens plane and the detector plane may be nonparallel with respect to each other creating a wedge shaped depth of field. In this manner, return light pulses from far away and nearby targets may stay in focus.