Lidar Optical Layout Using a Negative Cylindrical Lens for Angular Resolution
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Solution Overview
Problem
Existing lidar systems face challenges in achieving high angular resolution due to asymmetric emission areas and divergence angles of laser beams, which result in asymmetric return beam spots and limited resolution.
Innovation Solution
The use of a cylindrical lens with negative power in combination with a rotationally symmetric lens to transform the emission area into a virtual area with symmetric divergence angles, paired with an array of photo sensors to detect and process return laser pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional laser source with asymmetric emission area is used, then the device complexity is low, but the measurement precision is limited due to asymmetric return beam spots
Solution Approach 1:
A cylindrical lens with negative power is introduced as an intermediary optical element between the laser source and the far-field. This lens transforms the asymmetric emission area into a virtual emission area with symmetric divergence angles, thereby producing symmetric return beam spots and improving angular resolution without requiring complex detector arrays or processing systems
Solution Approach 2:
The optical parameters of the laser beam are changed by using a cylindrical lens with a specific negative power value. This lens modifies the divergence angles in the fast axis direction, transforming them to match the slow axis divergence angles, thereby achieving symmetric beam characteristics and enhanced measurement precision
2Measurement precision
If the emission area is reduced to improve resolution, then the measurement precision improves, but the use of energy by the laser source decreases
Solution Approach 1:
The cylindrical lens acts as a mediator that allows the full laser emission area to be utilized while transforming the asymmetric beam pattern into a symmetric one. This enables maintaining high energy output from the laser source while achieving improved angular resolution through the modified beam divergence, eliminating the need to reduce emission 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 achieves improved resolution by ensuring symmetric far-field beam spots and allows for enhanced detection capabilities, enabling better three-dimensional imaging.
Implementation Method 1
a cylindrical lens with a negative power... configured to transform the emission area of a laser beam emitted by the laser source into a virtual emission area
Implementation Method 2
a rotationally symmetric lens... configured to collimate and direct the laser beam towards a far-field
Implementation Method 3
a receiving lens... configured to receive and focus the return laser beam to a return beam spot at a focal plane
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An optical system includes a laser source having an emission area that has a first width in a first direction and a first height in a second direction orthogonal to the first direction, the first width being greater than the first height. The optical system further includes a cylindrical lens having a negative power and positioned in front of the laser source. The cylindrical lens is oriented such that a power axis of the cylindrical lens is along the first direction. The cylindrical lens is configured to transform the emission area of a laser beam emitted by the laser source into a virtual emission area having a virtual width and a virtual height, where the virtual width is less than the first width. The optical system further includes an rotationally symmetric lens positioned downstream from the cylindrical lens and configured to collimate and direct the laser beam towards a far-field.