Non-imaging Optical Element for LiDAR Sensor Protection
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Solution Overview
Problem
High-performance optical scanners face challenges in achieving high spatial and temporal resolution with good signal-to-noise ratio due to high-intensity light beams and high-speed scanning, which results in sensor damage and reduced detection efficiency from high irradiance and large sensing areas required to compensate for lag angles.
Innovation Solution
Incorporating a non-imaging optical element between the focal plane and the sensor to spread the focused light over a larger area, reducing peak irradiance and stabilizing the beam independent of mirror speed and target distance, using elements like ball lenses or compound parabolic concentrators with diffusers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-power light beams and high-speed scanners are used to achieve high spatial and temporal resolution with good signal-to-noise ratio, then detection capability is improved, but sensor damage occurs due to high irradiance
Solution Approach 1:
A non-imaging optical element is introduced as an intermediary component between the collection optics and the sensor. This element redistributes the concentrated light from the focal plane across a larger area, reducing peak irradiance on the sensor while preserving the total light signal. The intermediary element thus mediates between the high-intensity light beam requirement and the sensor protection requirement.
Solution Approach 2:
The patent transitions from a point-focused light distribution (zero-dimensional concentration at the focal plane) to a two-dimensional distribution across the sensor surface. By spreading the light in the lateral dimension rather than maintaining tight focal concentration, the peak irradiance is reduced while the total signal remains available for detection.
2Area of stationary object
If large sensing areas are used to compensate for lag angles in high-speed scanning, then detection coverage is improved, but detection efficiency decreases
Solution Approach 1:
The non-imaging optical element creates a controlled distribution of light intensity across the sensor surface, optimizing the local quality of light reception. Rather than uniformly illuminating a large area, the element concentrates light efficiently onto an optimized sensor area while accounting for lag angle effects, thus maintaining high detection efficiency without requiring excessive sensor area.
3Illumination intensity
If collection optics focus light onto a small focal plane, then light concentration is improved, but peak irradiance damages the sensor
Solution Approach 1:
The non-imaging optical element serves as a mediator that receives the concentrated light from the focal plane and redistributes it. This intermediary function allows the system to maintain the benefit of light concentration during collection while preventing the harmful effect of peak irradiance damage at the sensor location.
Solution Approach 2:
The patent applies dimensional transformation by taking light concentrated in a small focal area and redistributing it across a two-dimensional sensor surface. This dimensional expansion reduces the intensity (power per unit area) while preserving the total optical power, thus maintaining detection sensitivity without causing damage.
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 reduces sensor damage risk, lowers dark noise, and increases signal bandwidth, enabling longer detection ranges and higher resolution without the need for large sensing areas, thus enhancing the performance of optical scanners like LiDAR systems.
Implementation Method 1
a collection lens positioned to receive the light from the scene that is reflected from the at least one scanning mirror and to focus the collected light onto a focal plane
Implementation Method 2
a non-imaging optical element having a front surface positioned at the focal plane of the collection lens and a rear surface in proximity to the sensor and configured to spread the light focused by the collection lens over the detection area of the sensor
Implementation Method 3
the non-imaging optical element includes a ball lens. In one embodiment, the ball lens is configured to image a pupil of the collection lens onto the sensor
Implementation Method 4
the non-imaging optical element includes a compound parabolic concentrator (CPC) having an entrance oriented toward the collection lens and an exit oriented toward the sensor
Implementation Method 5
a transmitting diffuser extending across the entrance of the CPC. In one embodiment, the transmitting diffuser is in contact with the entrance of the CPC
Data Source
AI summary
An optical device includes a light source, which is configured to emit a beam of light, and a sensor having a detection area. At least one scanning mirror is configured to scan the beam across a target scene. Light collection optics include a collection lens positioned to receive the light from the scene that is reflected from the at least one scanning mirror and to focus the collected light onto a focal plane, and a non-imaging optical element having a front surface positioned at the focal plane of the collection lens and a rear surface in proximity to the sensor and configured to spread the light focused by the collection lens over the detection area of the sensor.