SWIR Image Sensor Synchronization for Dark Noise Rejection
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Solution Overview
Problem
Short-wave infrared (SWIR) image sensors suffer from severe dark currents and environment light interference, which degrade image quality.
Innovation Solution
The method involves generating periodic SWIR pulses and an index signal, which is used to synchronize and collect data from the image sensor, thereby screening out dark noise and environment light signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous illumination is used for imaging, then image sensor can continuously capture light signals, but dark current and environment light interference severely degrade image quality
Solution Approach 1:
The patent applies periodic pulsed illumination instead of continuous illumination. The illumination source emits light in periodic pulses, and the image sensor is synchronized to capture signals only during these pulse periods. This periodic action allows the system to distinguish between illumination-induced signals and continuous background noise (dark current and environment light), thereby improving image quality while maintaining continuous imaging capability.
2Loss of information
If image sensor operates continuously to capture reflected light, then complete object profile can be obtained, but dark noise and environment light signals contaminate the measurement
Solution Approach 1:
The system uses periodic pulsed illumination with synchronized detection windows. By capturing signals only during the illumination pulse periods and excluding signals between pulses, the system obtains complete object profile information while eliminating contamination from dark noise and environment light that occur during the non-illumination periods.
Solution Approach 2:
The system employs a control mechanism that uses the periodic illumination signal as a reference (index signal) to gate the image sensor operation. This feedback-based synchronization ensures that the sensor is active only when illumination is present, creating a closed-loop system that automatically rejects out-of-phase noise signals and maintains accurate object profile measurement.
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 improves image quality by effectively eliminating dark current and environment light noise, resulting in a pure signal that accurately reflects the object's profile.
Implementation Method 1
An image sensor is configured to receive the SWIR pulses reflected from the object and generate a sensor signal based on the SWIR pulses
Data Source
AI summary
A method includes generating light pulses by an illumination source toward an object; collecting the light pulses reflected from the object by an image sensor; generating a first signal-time plot of a sensor signal by the image sensor; generating a second signal-time plot of an index signal, wherein the second signal-time plot of the index signal comprises pulsed signals corresponding to the light pulses, respectively; collecting data from selected time periods of the first signal-time plot of the sensor signal, wherein the selected time periods of the first signal-time plot of the sensor signal are the same as time periods of the light pulses in the second signal-time plot of the index signal; and generating a third signal-time plot of an output signal based on the collected data.