Upconversion Image Sensor for SWIR Pulse Frequency Decoding
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Solution Overview
Problem
Existing image sensors struggle to detect and decode the pulse repetition frequency of short wave infrared (SWIR) laser pulses, which is crucial for identifying friend or foe in various applications.
Innovation Solution
A silicon-based image sensor with a pixel array and an upconversion layer of crystals on its front or backside, cooperating with a pulse repetition frequency decoder, which uses the known frame rate and decay time of upconverting emissions to decode the pulse repetition frequency of captured laser flashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed circuitry is used to detect and decode SWIR laser pulses, then measurement precision of pulse repetition frequency is improved, but device complexity increases
Solution Approach 1:
An upconversion layer is introduced as an intermediary between the SWIR laser pulses and the silicon-based image sensor. This layer converts SWIR photons to visible light photons, enabling the sensor to detect SWIR laser pulses using its existing visible light detection capabilities without requiring complex high-speed SWIR detection circuitry
Solution Approach 2:
The patent replaces complex electronic detection circuitry with a photonic conversion approach. Instead of using sophisticated electronic systems to directly detect and measure SWIR laser pulse repetition frequencies, the system uses optical upconversion to transform the problem into a visible light detection task that can be handled by standard image sensors
2Measurement precision
If the frame rate of the image sensor is increased to capture SWIR laser pulses, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The upconversion layer serves as a mediator that enables accurate measurement of fast SWIR laser pulses using a slow frame rate image sensor. By converting SWIR photons to visible light, the system can capture pulse timing information at lower frame rates while maintaining measurement precision
Solution Approach 2:
The patent exploits the periodic nature of laser pulse repetition by using the upconversion layer to accumulate and integrate pulse signals over multiple frames. This allows the system to achieve accurate pulse repetition frequency measurement through periodic sampling at lower frame rates rather than requiring continuous high-speed capture
3Adaptability or versatility
If the wavelength range sensitivity of the image sensor is extended to SWIR, then adaptability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system segments the wavelength conversion function from the image sensor itself by introducing a separate upconversion layer. This allows the silicon-based image sensor to maintain its native visible light detection capabilities while the upconversion layer handles SWIR to visible light conversion, avoiding the need to manufacture complex multi-wavelength sensors
Solution Approach 2:
The patent employs composite material structure combining silicon-based image sensor with upconversion layer materials. This composite approach enables the system to detect SWIR radiation by combining the advantages of silicon sensors (mature manufacturing, high visible light sensitivity) with upconversion materials (SWIR absorption and visible light emission capabilities)
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
Enables the detection and decoding of SWIR laser pulses at a relatively slow frame rate, extending the wavelength range sensitivity of the image sensor and allowing for accurate identification of laser sources without additional high-speed circuitry.
Implementation Method 1
an upconversion layer of crystals on at least one of a front side and a backside of the silicon-based image sensor
Implementation Method 2
The pulse repetition frequency decoder can use a known frame rate of the silicon-based image sensor and a decay time of an upconverting emission from the upconversion layer of crystals to decode the pulse repetition frequency of the laser flash
Data Source
AI summary
A silicon-based image sensor can have i) a pixel array with one or more pixels and ii) an upconversion layer of crystals on at least one of a front side and a backside of 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 captured by one or more of the pixels of the silicon-based image sensor. The pulse repetition frequency decoder can use a known frame rate of the silicon-based image sensor and a decay time of an upconverting emission from the upconversion layer of crystals to decode the pulse repetition frequency of the laser flash.