Quantum Efficiency Measurement Using Single Laser Pulse
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Solution Overview
Problem
Current methods for measuring quantum efficiency of detectors face challenges in accurately comparing detectors with significantly different sensitivities, particularly when using spectral light sources, as they often require high-cost lasers and are prone to measurement errors due to non-uniform light distribution and interference phenomena.
Innovation Solution
An apparatus and method utilizing a single laser pulse from a wavelength-variable nanosecond laser to compare signal values between a reference detector and a measurement target detector, with an optical fiber maintaining a stable beam profile and amplifying the signals to calculate relative quantum efficiency, allowing for direct comparison even between detectors with large sensitivity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a very low temperature absolute radiometer is used for absolute measurement of quantum efficiency, then measurement accuracy is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent introduces a reference detector as an intermediary component with known quantum efficiency characteristics. By comparing the measurement target detector against this reference detector using a laser pulse system, the patent achieves accurate quantum efficiency measurements without requiring a complex absolute radiometer. The reference detector serves as a mediator that simplifies the measurement system while maintaining accuracy.
Solution Approach 2:
The patent creates a simplified copy of the measurement process by using a laser pulse source that can be reproducibly positioned and directed. Instead of using a complex absolute radiometer, the system uses a laser pulse that can be precisely controlled and repeated, allowing the quantum efficiency to be measured through comparison with the reference detector. This copying approach maintains measurement accuracy while reducing system complexity.
2Device complexity
If comparison method is used for quantum efficiency measurement, then device complexity is reduced, but measurement precision deteriorates when detectors have significantly different sensitivities
Solution Approach 1:
The patent changes the parameter of light delivery by using a laser pulse system with precise spatial and temporal control. The laser pulse can be positioned to illuminate both detectors accurately, and its characteristics can be adjusted to ensure both detectors operate within their linear response ranges. This parameter change enables accurate comparison between detectors with significantly different sensitivities.
Solution Approach 2:
The patent implements feedback through the signal processing system that continuously monitors and adjusts the measurement process. The system records voltage signals from both detectors, processes them to account for different sensitivities, and calculates quantum efficiency based on the ratio of signals. This feedback mechanism ensures accurate measurements even when detectors have large sensitivity differences.
3Adaptability or versatility
If spectral light source is used for quantum efficiency measurement, then measurement versatility is improved, but measurement precision deteriorates due to non-uniform light distribution and interference phenomena
Solution Approach 1:
The patent uses periodic laser pulses instead of continuous spectral light. The pulsed nature of the laser allows for precise temporal control and eliminates interference phenomena that occur with continuous light sources. Each pulse can be independently controlled for wavelength and intensity, enabling accurate measurements across different wavelengths without the non-uniform light distribution problems of spectral light sources.
Solution Approach 2:
The patent replaces the mechanical/spectral light source system with a laser pulse system that uses electromagnetic radiation with precise temporal and spatial control. This substitution eliminates the non-uniform light distribution and interference phenomena associated with traditional spectral light sources, while maintaining the ability to measure across a wide wavelength range.
4Adaptability or versatility
If detectors with significantly different sensitivities are compared using traditional methods, then measurement versatility is improved, but measurement precision deteriorates due to sensitivity differences
Solution Approach 1:
The patent segments the measurement process into distinct components: a laser pulse source, a reference detector with known characteristics, and a measurement target detector. By separating these components and using the laser pulse to illuminate both independently, the system can accurately compare detectors with significantly different sensitivities. The segmentation allows each detector to be optimized for its specific function while maintaining comparability.
Solution Approach 2:
The patent creates equipotential conditions for comparison by using the laser pulse system to deliver controlled energy to both detectors. The system adjusts the laser pulse parameters to ensure that both detectors receive appropriate illumination levels, creating a fair comparison basis. This equipotentiality approach allows accurate quantum efficiency comparison even when detectors have large sensitivity differences.
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 precise measurement of quantum efficiency across a wide wavelength range with reduced uncertainty (2-4%), overcoming sensitivity differences and measurement errors, and extends the wavelength range of quantum efficiency measurement from 420 nm to 1600 nm.
Implementation Method 1
a reference detector absorbing a portion of the laser pulse output from the light source part and converting the absorbed portion of the laser pulse into a current signal
Implementation Method 2
a measurement target detector absorbing a laser pulse reflected from the reference detector and converting the absorbed laser pulse into a current signal
Implementation Method 3
an optical fiber coupling the laser pulse output from the light source part to fix a position of the laser pulse and maintaining a circular shape
Data Source
AI summary
Provided are an apparatus and method for measuring quantum efficiency of a detector using a single pulse laser. Quantum efficiency of the measurement target detector may be measured from 420 nm to 1600 nm having uncertainty of 2% to 4% (K=2) by comparing the reference detector and the measurement target detector significantly different in sensitivity using a single laser pulse as a spectral light source. Also, it is possible to directly compare the two detectors with a significant difference in sensitivity through a very simple setup that causes a portion of a laser pulse output from a light source part to be absorbed by the reference detector and the laser pulse reflected from the reference detector to be irradiated to the measurement target detector.