Decay-Time Scanner Control for Weak Luminescence Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional scanners face challenges in detecting weak luminescence light intensity signals from luminescent materials with short decay times, leading to inaccurate determination of decay time characteristics due to saturation and light intensity losses, especially when the light sensor is close to the material.
Innovation Solution
A high sensitivity light sensor with a bias regulator, photodiode, and an inverting transimpedance amplifier, along with a control unit that adjusts the excitation light intensity and measurement time to prevent saturation, allowing for accurate detection of weak luminescence signals without light guides, which reduces signal loss and enables faster recovery from excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light sensor is placed close to the luminescent material to improve detection sensitivity, then the ability to detect weak luminescence signals is improved, but the photodiode saturates due to high excitation light intensity
Solution Approach 1:
A light guide is introduced as an intermediary component between the excitation light source and the luminescent material. The light guide delivers excitation light to the material while preventing direct exposure of the photodiode to high-intensity excitation light, thus avoiding saturation. The light guide acts as a mediator that separates the excitation and detection paths, allowing the photodiode to detect weak luminescence signals without being overwhelmed by the excitation source.
Solution Approach 2:
The optical path is segmented into separate excitation and detection channels. The excitation light travels through the light guide to illuminate the luminescent material, while the photodiode detects emitted luminescence through a different optical path. This segmentation allows independent optimization of each function - strong excitation light delivery without compromising detector sensitivity.
2Object-affected harmful factors
If a light guide is used to deliver excitation light to prevent saturation, then saturation is avoided, but light losses occur during luminescence collection
Solution Approach 1:
The light guide serves as an intermediary that efficiently couples the excitation source to the luminescent material while minimizing light losses. By using optimized light guide geometry and positioning, the system delivers sufficient excitation light to the material without requiring excessive input power, thereby reducing overall energy losses in the system.
Solution Approach 2:
The system optimizes parameters such as light guide dimensions, positioning distance, and numerical aperture to maximize light coupling efficiency. By carefully adjusting these parameters, the light guide minimizes transmission losses while still preventing photodiode saturation, achieving an optimal balance between the two conflicting requirements.
3Illumination intensity
If the excitation light intensity is increased to improve signal strength, then the luminescence signal is stronger, but the photodiode saturation threshold is exceeded
Solution Approach 1:
The light guide acts as a spatial filter and directional controller, concentrating excitation light onto the luminescent material while preventing scattered high-intensity light from reaching the photodiode. This allows use of higher excitation intensities to strengthen the luminescence signal without compromising measurement precision by exceeding the photodiode's saturation threshold.
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 enables accurate detection of weak luminescence intensity profiles and precise determination of decay times, even for materials with short decay times, by preventing saturation and minimizing light losses, thus improving the scanner's sensitivity and measurement accuracy.
Implementation Method 1
a photodiode (1) mounted to operate in a photoconductive mode with a positive high voltage Vb applied at its cathode by means of a bias regulator (2)
Implementation Method 2
A luminescent material typically converts energy of an exciting radiation of a given wavelength into emitted light having another wavelength
Implementation Method 3
an inverting transimpedance amplifier including an operational amplifier (3) with a feedback resistor Rf and a feedback capacitor Cf mounted in parallel with the feedback resistor Rf between an inverting input terminal and an output voltage terminal (4) of the operational amplifier, the inverting input terminal of the operational amplifier (3) being connected to an anode of the photodiode (1) and operable to convert the delivered photocurrent intensity Ip into an output voltage signal Vout at the output voltage terminal (4)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosed scanner for detecting a decay time of light emitted by a luminescent material has a control unit operable to adapt the drive current, or the value of the drive voltage, powering its light source to accordingly adapt the intensity of excitation light delivered to the luminescent material so that its high sensitivity light sensor can reliably measure the luminescence light emitted in response to the excitation light, and thus accurately determine a corresponding decay time value.