Spatial Light Modulator for Lidar Receiver Noise Reduction
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Solution Overview
Problem
LIDAR systems face challenges in improving the signal-to-noise ratio (SNR) due to background noise from sunlight and other light sources, which can be addressed by existing mechanical systems that are bulky, costly, and require maintenance.
Innovation Solution
The use of a spatial light modulator (SLM), such as a digital micromirror device (DMD), that directs reflected light from a region of interest to a detector while diverting background light away, enhancing the SNR without the need for mechanical rotors or motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical mirrors or rotors are used to track the scanned laser beam, then the noise from background radiation is reduced, but the system becomes bulky, expensive, and requires maintenance
Solution Approach 1:
The patent replaces mechanical mirrors and rotors with a solid-state spatial light modulator (SLM) that uses an array of micromirrors controlled by electronics. This substitution eliminates moving mechanical parts while achieving the same function of directing light to reduce background noise. The SLM can be rapidly reconfigured electronically to track the scanned beam without requiring bulky mechanical rotation systems.
Solution Approach 2:
The patent divides the receiver aperture into multiple segments by using an array of micromirrors arranged in a grid pattern. Each micrometer can be independently controlled to direct light from specific regions of interest to the detector while blocking background radiation from other areas. This segmentation allows precise spatial filtering without requiring large mechanical structures.
2Object-affected harmful factors
If a narrow field of view optical system is used to track the scanned laser beam, then noise is reduced, but the system requires large, bulky and expensive mechanical mirrors and rotors
Solution Approach 1:
The patent replaces large mechanical mirrors and rotors with a compact spatial light modulator that uses an array of micromirrors. The SLM achieves narrow field of view tracking through electronic control of the micrometer array, eliminating the need for bulky mechanical components while maintaining the ability to reject background noise effectively.
Solution Approach 2:
The patent transitions from mechanical movement in physical space to electronic control in a different dimension. Instead of physically rotating large mirrors to track the beam, the system uses electronic addressability of the micrometer array to dynamically select and direct the appropriate spatial regions, achieving the same tracking function with a compact solid-state device.
3Measurement precision
If an array of detectors is used to collect all light from the FOV, then the system can detect reflected light, but the cost is prohibitive and performance is inferior
Solution Approach 1:
The patent extracts only the necessary portion of the field of view that corresponds to the scanned laser beam by using the spatial light modulator to selectively direct light from the region of interest to the detector. This extraction approach eliminates the need for a full array of detectors across the entire field of view, reducing cost and complexity while maintaining detection precision for the relevant signal.
Solution Approach 2:
The spatial light modulator acts as an intermediary between the field of view and the detector. Instead of using a direct array of detectors to capture all light, the SLM first processes and selects the appropriate spatial information, then delivers it to a single detector. This intermediary approach simplifies the system while maintaining measurement precision.
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 approach significantly improves the SNR by focusing only on the light reflected from the region of interest, reducing noise and maintaining high performance with solid-state components, thus increasing the accuracy and efficiency of LIDAR systems.
Implementation Method 1
receiving light from a field of view on a spatial light modulator... directing light from the portion of the two-dimensional array to a photodiode
Data Source
AI summary
In described examples, a method includes receiving light from a field of view on a spatial light modulator that includes a two-dimensional array of picture elements in rows and columns; and determining a portion of the two-dimensional array that corresponds to a region of interest in response to a transmit scan beam illuminating the field of view. The method also includes directing light from the portion of the two-dimensional array to a photodiode, and directing light outside the portion away from the photodiode.