Silicon Image Sensor Upconversion Layer for Laser Pulse Detection
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Solution Overview
Problem
Existing imaging systems struggle to effectively detect and decode the pulse repetition frequency of laser flashes, especially in bright or varying lighting conditions, due to interference from visible and near-infrared wavelengths.
Innovation Solution
A silicon-based image sensor with an upconversion layer of crystals is used in conjunction with a second image sensor, where the upconversion layer absorbs and converts SWIR wavelengths into a detectable range, allowing for the decoding of pulse repetition frequency using a pulse repetition frequency decoder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single image sensor is used to detect laser pulses, then the device complexity is reduced, but the measurement precision of pulse repetition frequency deteriorates due to interference from visible and near-infrared wavelengths
Solution Approach 1:
The system divides the detection function into two separate image sensors: a first image sensor with an upconversion layer dedicated to SWIR laser detection, and a second image sensor for visible and near-infrared imaging. This segmentation allows each sensor to specialize in specific wavelength ranges, eliminating cross-interference and improving measurement precision without requiring a single complex multi-wavelength sensor.
Solution Approach 2:
The upconversion layer acts as an intermediary component that converts SWIR laser wavelengths into visible or near-infrared wavelengths that the first image sensor can detect. This intermediary conversion process enables precise laser pulse detection by transforming the laser wavelength into a range where the sensor has high quantum efficiency, while the second sensor simultaneously captures the original scene without laser interference.
2Reliability
If an upconversion layer is added to the first image sensor, then the detection capability for SWIR laser pulses is improved, but the device complexity increases
Solution Approach 1:
The system merges the upconversion layer with the first image sensor to create an integrated SWIR detection module. This combination allows the first sensor to specifically detect converted laser wavelengths while the second sensor captures the full visible and near-infrared spectrum, achieving reliable multi-wavelength detection through functional integration rather than separate systems.
Solution Approach 2:
The first image sensor with the upconversion layer serves multiple functions: it detects the converted SWIR laser wavelengths and simultaneously allows the second sensor to capture the original scene. This multi-functionality approach enables the system to perform both laser detection and general imaging without requiring completely separate systems, thereby improving reliability while managing complexity.
3Measurement precision
If multiple image sensors are used to detect different wavelength ranges, then the measurement precision of laser pulse repetition frequency is improved, but the device complexity increases
Solution Approach 1:
The detection system is segmented into two specialized image sensors: the first sensor with an upconversion layer for SWIR laser detection and the second sensor for visible and near-infrared imaging. This segmentation enables each sensor to operate in its optimal wavelength range without interference, achieving high measurement precision for pulse repetition frequency while distributing the complexity across two simpler, specialized components rather than one complex multi-wavelength sensor.
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 solution enables the detection and decoding of laser pulses in various lighting conditions, including bright sunlight, by isolating SWIR wavelengths and reducing noise interference, thus improving the accuracy and reliability of laser identification.
Implementation Method 1
an upconversion layer of crystals on the first silicon-based image sensor... which will be absorbed and converted by the upconversion layer of crystals into a third range of wavelengths
Data Source
AI summary
A silicon-based image sensor has an upconversion layer of crystals. The silicon-based image sensor receives light from a common beam splitter with a second image sensor. An optical band pass filter cooperates with the common beam splitter to pass some of the light to be incident on the upconversion layer of crystals in a second range of wavelengths, which will be absorbed and converted by the upconversion layer of crystals into a third range of wavelengths, and then the third range of wavelengths is transmitted onto the pixels in the silicon-based image sensor. A pulse repetition frequency decoder cooperates with the upconversion layer of crystals to decode a pulse repetition frequency of a laser flash in the second range of wavelengths passed by the optical band pass filter and subsequently upconverted by the upconversion layer of crystals and then captured by the pixels of the silicon-based image sensor.