Lidar Optical Sensor Hot Pixel Noise Reduction
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Solution Overview
Problem
Existing LIDAR devices suffer from parasitic electrical charges introduced by clocking operations, leading to 'Hot Pixels' that affect measurement accuracy and increase with operation duration, particularly in detecting Mie and Rayleigh scattering for aerodynamic velocity measurements.
Innovation Solution
A CMOS or CCD-based optical sensor design that excludes defective cells due to parasitic charges, performs two-stage groupings of photodetection charges for Mie and Rayleigh scattering, and integrates signals to improve signal-to-noise ratio, allowing simultaneous detection of both scattering types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the optical sensor operates for extended periods to acquire aerodynamic velocity profiles, then measurement coverage and data quality improve, but parasitic charges accumulate causing Hot Pixels that degrade measurement accuracy
Solution Approach 1:
The patent applies preliminary action by performing a dark reference measurement before the actual aerodynamic velocity profile acquisition. This reference measurement captures the baseline signal including any parasitic charges present at the start of operation. By subtracting this reference signal from subsequent measurements, the system eliminates the impact of accumulated parasitic charges (Hot Pixels) on measurement accuracy, enabling extended operation without degradation.
2Difficulty of detecting and measuring
If separate optical sensors are used for Mie scattering and Rayleigh scattering detection, then detection specificity improves, but device complexity and development costs increase
Solution Approach 1:
The patent implements universality by designing a single optical sensor that can detect both Mie scattering and Rayleigh scattering signals. The sensor uses wavelength-selective optics and spectral filtering to differentiate between the two scattering types, allowing one sensor to perform multiple detection functions. This reduces device complexity and development costs while maintaining detection specificity for both atmospheric phenomena.
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
Enhances measurement accuracy by reducing read noise and improving signal-to-noise ratio, enabling precise aerodynamic velocity profiling through Mie and Rayleigh scattering without increasing design and development costs.
Implementation Method 1
an array of photodetectors arranged in a matrix having a plurality of columns and a plurality of lines, each photodetector being sensitive to radiation in a spectral band extending from the ultraviolet to the near-infrared
Implementation Method 2
capable of detecting the scattering of radiation by particles suspended in the atmosphere, known as Mie scattering
Implementation Method 3
the scattering of radiation by molecules contained within the atmosphere, known as Rayleigh scattering
Implementation Method 4
They are carried by the wind in the relevant atmospheric region, which causes a Doppler shift in the portion of the radiation they backscatter
Data Source
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Figure 3a
AI summary
The invention relates to an optical sensor (5) which comprises an array (M60) of photodetectors (60) and is suitable for detecting a fringe position that can be produced from Mie backscattering radiation or for detecting intensities of interference patterns that can be produced from Rayleigh backscattering radiation. Such an optical sensor can be a CMOS sensor or a CCD. It can be used in a LIDAR device, in particular a LIDAR device that is on-board a satellite to provide airspeed profiles through the Earth's atmosphere.