Avalanche Photodiode Multicolor Imaging Single Pixel
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Solution Overview
Problem
Conventional imaging devices require multiple focal plane arrays and complex fabrication techniques to image two distinct wavebands, leading to increased size, weight, and power consumption due to the need for separate electrical connections for different color-sensitive pixels.
Innovation Solution
A multicolor imaging device using an avalanche photodiode with a material composition where only one carrier causes impact ionization, allowing the photodiode's gain to vary with photon energy, enabling simultaneous imaging of multiple colors in a single pixel with a single electrical connection to the readout integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple focal plane arrays are used to image two distinct wavebands, then imaging capability is improved, but size, weight, and power consumption increase
Solution Approach 1:
The patent merges multiple waveband imaging capabilities into a single focal plane array by using a single photodiode material that responds to multiple wavelengths. This eliminates the need for separate focal plane arrays for different wavebands, thereby reducing device weight while maintaining multi-waveband imaging capability.
Solution Approach 2:
The invention makes a single photodiode universal by selecting materials that are sensitive to multiple wavebands simultaneously. This allows one pixel to perform multiple imaging functions across different wavelengths, replacing the need for multiple specialized arrays and reducing overall device weight.
2Measurement precision
If separate electrical connections are provided for different color-sensitive pixels, then imaging precision is improved, but device complexity and SWaP increase
Solution Approach 1:
The patent combines multiple color-sensitive detection functions into a single pixel with a single electrical connection. By using photodiode materials that inherently respond to multiple wavelengths, the system maintains imaging precision while eliminating the need for separate electrical connections for different colors, thereby reducing device complexity.
3Difficulty of detecting and measuring
If different materials and fabrication steps are used for each photodiode, then wavelength sensitivity is improved, but manufacturing complexity increases
Solution Approach 1:
The invention uses homogeneous photodiode materials that inherently possess sensitivity to multiple wavebands. This eliminates the need for different materials and fabrication steps for different wavelengths, simplifying manufacturing while maintaining the ability to detect multiple wavelengths simultaneously.
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
The solution enables reduced size, weight, and power consumption while allowing for simultaneous multicolor imaging, overcoming the limitations of conventional devices by processing a single output signal to extract information from different wavelengths, thereby enhancing imaging capabilities without the need for complex fabrication or multiple connections.
Implementation Method 1
The photodiode produces an output signal that includes at least two components produced in response to two different wavelengths of incident light
Implementation Method 2
an avalanche photodiode having a material composition such that only one carrier causes substantially all of the impact ionization that occurs within the photodiode
Data Source
AI summary
A multicolor imaging device capable of imaging two or more wavelengths with a single pixel comprises an avalanche photodiode having a material composition such that only one carrier causes substantially all of the impact ionization that occurs within the photodiode. The photodiode is arranged such that, when reverse-biased, the photodiode's gain varies with the photon energy of incident light. The photodiode, preferably a PIN avalanche photodiode or a separate absorber-multiplier photodiode, produces an output signal which can include at least two components produced in response to two different wavelengths of incident light. Circuitry receiving the output signal would typically include a means of extracting each of the components from the output signal.