Optical Signal Coherent Detection for Real-Time Quantum Efficiency
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Solution Overview
Problem
Existing optical measurement systems are task-specific and difficult to re-configure, making it challenging to measure properties like extrinsic and intrinsic quantum efficiency simultaneously without using lock-in functionality, especially when specimens cannot respond to the frequency of modulation.
Innovation Solution
A system that includes a modulation frequency source, a modulated light source, and a specimen measurement system with detectors for incident and reflected light, along with a data acquisition circuit and computing device for software-based coherent detection, allowing simultaneous sampling and digitization of signals to calculate properties like EQE and IQE in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated lock-in amplifier is used to extract signals from noise, then measurement precision is improved, but device complexity and task-specificity increase, making it difficult to re-configure for different measurement types
Solution Approach 1:
The patent replaces dedicated lock-in amplifier hardware with a universal computing device that performs coherent detection through software. This single computing device can handle multiple measurement types (EQE, IQE, and other properties) by executing different software algorithms, eliminating the need for task-specific hardware configurations while maintaining noise rejection capabilities.
Solution Approach 2:
The patent substitutes the mechanical/electronic lock-in amplifier system with a software-based coherent detection system running on a computing device. The signal processing function is migrated from dedicated hardware to flexible software, allowing the same physical system to perform multiple measurement functions without hardware reconfiguration.
2Measurement precision
If separate measurements are performed for EQE and IQE, then measurement precision for each property is maintained, but measurement time increases and signals may not be captured at the same time instance
Solution Approach 1:
The patent combines multiple measurement functions (EQE and IQE) into a single simultaneous measurement process. The computing device processes multiple detector signals concurrently using software-based coherent detection, extracting both EQE and IQE from signals captured at the same time instance, thereby reducing total measurement time while maintaining precision.
Solution Approach 2:
The system continuously processes multiple measurement signals simultaneously rather than sequentially. The computing device performs parallel coherent detection on multiple detector outputs, ensuring continuous acquisition of all required measurement data without interruption or time delays between different property measurements.
3Device complexity
If DC sampling is used to measure signals, then device complexity is reduced, but measurement precision deteriorates due to prevalent noise
Solution Approach 1:
The patent changes the sampling approach from simple DC sampling to synchronized digital sampling at the modulation frequency. The data acquisition circuit samples detector signals at the same rate and phase as the light source modulation, enabling coherent detection that rejects noise while maintaining system simplicity through software-based processing rather than complex hardware lock-in amplifiers.
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 simultaneous and accurate measurement of extrinsic and intrinsic quantum efficiency in real-time, reducing noise and inaccuracy by ensuring all measurements are based on signals acquired at the same time instance, facilitating flexible configuration for various measurement tasks.
Implementation Method 1
a light source to generate light
Implementation Method 2
the intensity, frequency, or phase of the incident light is modulated at a frequency
Implementation Method 3
the specimen may produce polarized or unpolarized reflected light, polarized or unpolarized transmitted light, and electrical signal (e.g., current and voltage) in response to the stimulus
Implementation Method 4
The dedicated lock-in amplifier receives and mixes the detector signal with a signal with an established phase relationship with the modulation frequency (often referred to as coherent or heterodyne detection)
Implementation Method 5
The dedicated lock-in amplifier receives and mixes the detector signal with a signal with an established phase relationship with the modulation frequency (often referred to as coherent or heterodyne detection)
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Systems for measuring optical properties of a specimen are disclosed. The systems are configured to sample signals related to the measurement of the properties of a specimen, and perform software-based coherent detection of the signals to generate resulting measurements are based on the signals acquired at substantially the same time instance. This facilitates the displaying or generating of the desired measurements in real time. In one configuration, the system is configured to direct a modulated light signal at a selected wavelength incident upon a specimen. In another configuration, the system is configured to direct a combined light signal, derived from a plurality of light signals at different wavelengths and modulated with different frequencies, incident upon a specimen. In yet another configuration, the system is configured to direct a plurality of light signals modulated with different frequencies incident upon different regions of a specimen.