LiDAR Optical Layout for Distant Detection With Less Stray Light
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Solution Overview
Problem
LiDAR systems face challenges in detecting distant objects effectively due to the reduction in reflected light intensity, leading to increased unnecessary light generation and scattering, which lowers detection precision and accuracy.
Innovation Solution
A detecting apparatus is designed with a telescope that increases the diameter of the illumination light flux while decreasing the diameter of the reflected light flux, and the driven mirror is positioned to prevent the optical path of the illumination light from coinciding with the telescope's optical axis, thereby reducing unnecessary light reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a telescope is arranged near the emission side to increase the diameter of illumination light flux, then the reception of reflected light from distant objects is improved, but the generation and reception of unnecessary light through reflection and scattering inside the detecting apparatus increases
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the optical axis of the telescope with the optical path of the illumination light. Specifically, the optical axis of the telescope is set to be different from the optical path of the illumination light at the center angle of view in the scanning range of the deflection unit. This asymmetric arrangement ensures that reflected light from distant objects can enter the telescope and be focused onto the light receiving element, while unnecessary light generated inside the apparatus is directed away from the optical axis and suppressed from reaching the detector
Solution Approach 2:
The patent applies local quality by creating different optical path characteristics for different regions of the light flux. The optical system is designed so that reflected light from distant objects follows a specific path that is focused onto the light receiving element, while illumination light and its reflections follow different paths. This is achieved through the specific arrangement where the optical axis of the telescope does not coincide with the optical path of the illumination light, creating region-specific optical properties that allow useful light to be received while blocking unnecessary light
2Quantity of substance
If the diameter of illumination light flux is increased to improve reception of reflected light, then the amount of light received from distant objects is improved, but the amount of unnecessary light generated by reflection and scattering inside the detecting apparatus increases
Solution Approach 1:
The patent uses asymmetry to separate the optical paths of useful light and unnecessary light. By setting the optical axis of the telescope to be different from the optical path of the illumination light at the center angle of view, the system allows increased illumination light flux diameter to improve reflected light reception while the asymmetric arrangement ensures that unnecessary light generated inside the apparatus is directed away from the telescope's optical axis and suppressed from reaching the light receiving element
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 the reception of reflected light from distant objects, improves detection resolution, and suppresses unnecessary light, resulting in more accurate distance measurement and object sizing for automated driving applications.
Implementation Method 1
a light source configured to emit an illumination light flux
Implementation Method 2
a deflection unit configured to deflect the illumination light flux toward the object in order to scan the object and configured to deflect the reflected light flux toward the light receiving element
Implementation Method 3
a splitting unit configured to allow the illumination light flux from the light source to proceed toward the deflection unit and configured to allow the reflected light flux from the deflection unit to proceed toward the light receiving element
Implementation Method 4
a first telescope configured to increase a diameter of the illumination light flux deflected by the deflection unit and configured to decrease a diameter of the reflected light flux from the object
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3C
AI summary
Provided is a detecting apparatus including a light source emitting an illumination light flux, a light receiving element receiving a reflected light flux from an object, a deflection unit deflecting illumination light flux toward the object to scan the object and deflecting reflected light flux toward light receiving element, a splitting unit allowing illumination light flux from light source to proceed toward deflection unit and allowing reflected light flux from deflection unit to proceed toward light receiving element, and a first telescope increasing a diameter of illumination light flux deflected by deflection unit, and decreasing a diameter of reflected light flux from the object in which the deflection unit is arranged so that a light path of a principal ray of illumination light flux at a center angle of view in a scanning range of deflection unit is prevented from coinciding with an optical axis of first telescope.