Light Quantity Detection Device with Dynamic Threshold Switching
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Solution Overview
Problem
Existing light quantity detection devices face challenges in accurately measuring weak light quantities due to deteriorated S/N ratio and photon count loss, especially when transitioning from weak to strong light conditions, and require separate analog and photon count measurement methods, leading to increased device complexity and non-linear output.
Innovation Solution
A light quantity detection device incorporating a light detector, amplifier, A/D converter, threshold value processing circuit, and number-of-photons calculation circuit that amplifies and digitizes detection signals, applies threshold processing, and calculates photon intensity based on signal waveform dimensions, enabling wide dynamic range detection from weak to strong light quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the analog measuring method is used to detect weak light quantity, then the detection range is extended, but the measurement precision deteriorates due to deteriorated S/N ratio
Solution Approach 1:
The patent dynamically switches between analog measuring method and photon count measuring method based on the detected light quantity level. When light quantity is strong, analog method is used; when light quantity is weak, photon count method is used. This dynamic adaptation resolves the contradiction by selecting the appropriate measurement method for each light quantity level, maintaining both wide detection range and high measurement precision.
2Measurement precision
If the photon count measuring method is used to detect weak light quantity, then the measurement precision is improved, but photon count loss occurs when light quantity increases
Solution Approach 1:
The system dynamically switches measurement methods based on light quantity intensity. Photon count method is used for weak light to maintain high precision, while analog method is used for strong light to prevent photon count loss. This dynamic switching resolves the contradiction between precision and information loss across different light quantity levels.
3Adaptability or versatility
If separate analog and photon count measurement methods are used, then the light quantity can be detected in wide dynamic range, but the device complexity increases
Solution Approach 1:
The patent merges the analog measuring method and photon count measuring method into a single integrated light quantity detection device. The device includes both detection circuits and a switching mechanism that automatically selects the appropriate method based on light quantity level. This merging approach achieves wide dynamic range detection while managing device complexity through unified control.
Solution Approach 2:
The light quantity detection device is designed with multi-functionality, capable of performing both analog measurement and photon count measurement. This universal design allows a single device to handle various light quantity levels effectively, achieving wide dynamic range detection without requiring separate dedicated devices for each measurement type.
4Measurement precision
If the integration time is increased to improve measurement precision of weak light quantity, then the output value increases, but the measurement time is extended
Solution Approach 1:
The patent changes the measurement method parameter based on light quantity level. Instead of always using long integration times with analog method, the system switches to photon count method for weak light detection. This parameter change allows achieving high measurement precision for weak light without requiring extended measurement times, as photon count method provides high precision through direct photon counting rather than integration.
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 allows for precise detection of light quantities across a wide dynamic range, improving measurement precision and reducing device complexity by accurately counting photons and handling noise signals, while shortening measurement time and enhancing S/N ratio.
Implementation Method 1
a light detector 31 which detects light incident thereon and generates an output signal
Data Source
AI summary
To enable measurement over a wide dynamic range from weak light quantity to strong light quantity in a light quantity detection device for detecting the light quantity, a detection signal from a photon counting light detector is A/D converted. When the A/D converted detection signal has a preset threshold value or more, the detection signal is transmitted as it is to a number-of-photons calculation circuit in a subsequent stage, and when the detection signal has the threshold value or less, threshold value processing for transmitting a preset reference value to the subsequent stage is performed. In the number-of-photons calculation circuit, the number of photons or the light quantity incident on the photon counting light detector is acquired from the dimension of an acquired detection signal waveform until the light quantity measurement ends.