Acousto-Optic Sensor Pixel With Phase Detection Circuit
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Solution Overview
Problem
Standard image sensors fail to acquire faithful images in biological media due to light scattering, and existing acousto-optic imaging techniques struggle to provide localized absorption information effectively.
Innovation Solution
A sensor with pixels comprising a photodiode, integration circuit, phase detection circuit, and phase control device, which integrates photocurrent into multiple capacitors and detects phase shifts to generate a signal representative of the phase of the modulated light signal, allowing for improved detection of light absorption in acoustic marking zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard image sensor is used to capture light in biological media, then the sensor structure is simple, but it cannot acquire faithful images due to light scattering
Solution Approach 1:
The sensor divides each pixel into multiple integration capacitors (e.g., 4 capacitors) that sequentially integrate photocurrent at different phases of the acoustic modulation cycle. This segmentation allows the sensor to capture phase-modulated light signals that carry absorption information through scattered light, resolving the contradiction between maintaining simple sensor structure and achieving faithful image acquisition.
Solution Approach 2:
The sensor employs periodic integration of photocurrent into multiple capacitors synchronized with the acoustic modulation frequency. By integrating signals periodically at different phases (0, π/2, π, 3π/2) and then combining them through phase detection circuits, the system extracts absorption information from phase-modulated signals while maintaining a relatively simple pixel structure.
2Loss of information
If acousto-optical imaging techniques are used to recover localized absorption information, then absorption information can be obtained, but the device complexity increases due to multiple integration capacitors and phase detection circuits
Solution Approach 1:
The patent combines multiple functions within each pixel: photodetection, periodic integration into multiple capacitors, phase detection, and signal combination are all integrated into a single pixel unit. This merging allows the sensor to recover localized absorption information while keeping the overall device structure compact and manageable, rather than requiring separate external processing components.
Solution Approach 2:
Each pixel is self-sufficient with its own set of integration capacitors and phase detection circuits. The pixel autonomously performs phase-demodulated integration and generates absorption information locally without requiring complex external processing, thereby reducing overall system complexity while maintaining the capability to recover localized absorption information.
3Measurement precision
If phase detection circuits are added to detect phase shifts, then measurement precision of light absorption improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces complex mechanical or external optical phase detection systems with integrated electronic phase detection circuits built directly into each pixel. By using electronic circuits to detect phase shifts of the modulated light signal, the system achieves high measurement precision for light absorption while avoiding the manufacturing complexities of mechanical phase detection mechanisms.
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 sensor effectively measures light absorption in both average and localized regions of the marking zone, enhancing the accuracy and detail of acousto-optic imaging by accounting for phase shifts and modulation patterns.
Implementation Method 1
a photodiode; an integration circuit configured to, at each period of the modulated light signal, integrate a photocurrent delivered by the photodiode
Implementation Method 2
an integration circuit configured to, at each period of the modulated light signal, integrate a photocurrent delivered by the photodiode successively into K capacitances
Implementation Method 3
a portion of the medium is subjected to an acoustic wave, typically an ultrasonic wave. The vibration of scatterers along the acoustic wave propagation path, also called the acoustic labeling zone or acoustic labeling column, modulates the phase of the scattered photons
Data Source
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AI summary
The present description relates to a sensor for the acquisition of a light signal modulated at an acoustic frequency, comprising a plurality of pixels each including: - a photodiode (52); - an integration circuit (70) configured to, at each period of the modulated light signal, integrate a photocurrent delivered by the photodiode successively into K capacitors (Ci), with K an integer greater than or equal to 2; and - a phase detection circuit (80) configured to detect an order of crossing a predetermined voltage threshold (TH) by the K capacitors and generate, according to the detected order, a signal (VPH) representative of the phase of the modulated light signal.