Pixel Voltage Compression for High-Speed Charged Particle Imaging
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Solution Overview
Problem
The limited bandwidth within the camera and/or between the camera and the image processor becomes a bottleneck for high-speed signal processing in charged particle microscopy systems, limiting data acquisition speed and quality.
Innovation Solution
A method involving multi-frame correlative double sampling (mfCDS) is combined with data compression to read pixel voltages multiple times without resetting the image sensor, digitizing them into a lower number of bits by removing the most significant bit (MSB) and adjusting the range to a valid range, allowing lossless reconstruction of pixel voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel voltage is digitized into a high number of bits to maintain data precision, then data quality is improved, but bandwidth requirements increase and limit readout speed
Solution Approach 1:
The pixel voltage readout process is segmented into multiple frames, where multiple frames of raw data are read out from the image sensor before resetting. This allows the system to process data in chunks, reducing the instantaneous bandwidth requirement while maintaining overall data precision through multi-frame correlative double sampling
Solution Approach 2:
The system changes the bit depth parameter dynamically - reading out data with higher precision during the accumulation phase, then compressing to lower bit depth for transfer and storage. This parameter transformation allows the system to maintain measurement precision during critical readout while reducing bandwidth requirements during data transfer
2Measurement precision
If the image sensor is reset frequently to maintain pixel voltage within range, then data quality is maintained, but readout speed decreases due to more frequent reset operations
Solution Approach 1:
The system performs preliminary accumulation of pixel voltage across multiple frames before resetting the sensor. By pre-accumulating charge information in the pixel wells across several frames, the system reduces the frequency of reset operations while still maintaining data quality through the correlative double sampling process that occurs during the accumulation phase
3Speed
If bandwidth within the camera and between camera and image processor is increased to improve readout speed, then readout speed is improved, but system complexity and cost increase
Solution Approach 1:
The system introduces an intermediary compression stage that transforms high-precision pixel voltage data into a compressed representation before transfer to the image processor. This intermediary step acts as a buffer that reduces bandwidth requirements without losing critical measurement information, as the compressed data can be decompressed and processed to recover the original measurement precision
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 enables high-speed data readout and processing with maintained data quality by reducing the bit depth of pixel voltages, increasing frame rates and overcoming bandwidth limitations.
Implementation Method 1
a camera for detecting charged particles emitted from a sample, digitizing the detected raw signal
Data Source
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AI summary
A method and system for acquiring data from a pixelated image sensor for detecting charged particles. The method includes reading a pixel voltage of one or more of the multiple pixels multiple times without resetting the image sensor and digitizing the pixel into a first number of bits. The camera outputs a digitized compressed pixel voltage in a second, less, number of bits. The maximum range of the digitized compressed pixel voltage is less than a maximum range of the pixel voltage.