Particle Measuring Device Calibration via Mean-Square Displacement
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Solution Overview
Problem
Existing particle size measurement methods, such as PTA, require conversion of pixel-based mean-square displacement to physical units, necessitating multiple equipment and challenging ambient temperature measurement, especially in flow fields.
Innovation Solution
A particle measuring device and calibration method using a calibration particle to directly measure and correct mean-square displacement in pixel units, allowing for accurate particle size calculation without physical unit conversion, and accounting for flow velocity distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel-based mean-square displacement is converted to physical units for particle size measurement, then measurement accuracy is improved, but device complexity and measurement difficulty increase due to requiring multiple equipment and temperature control
Solution Approach 1:
The patent introduces a calibration particle as an intermediary standard object with known physical size. By measuring the mean-square displacement of this calibration particle in pixel units and establishing a conversion relationship, the system creates a mediator that links pixel measurements to physical dimensions without requiring direct complex calibration equipment or temperature control during measurement
Solution Approach 2:
The patent performs calibration measurements using the calibration particle in advance to establish the conversion factor between pixel-based mean-square displacement and physical units. This preliminary action creates a lookup table or conversion formula that can be directly applied during subsequent particle size measurements, eliminating the need for real-time temperature measurement and complex equipment setup
2Measurement precision
If pixel-based mean-square displacement is converted to physical units for particle size measurement, then measurement accuracy is improved, but ease of operation deteriorates due to challenging ambient temperature measurement
Solution Approach 1:
The calibration particle serves as an intermediary that absorbs the complexity of temperature and viscosity dependencies. By calibrating with the calibration particle under the same environmental conditions as the target particles, the conversion factor automatically accounts for ambient temperature and medium properties, eliminating the need for separate temperature measurements
Solution Approach 2:
The system performs self-calibration by using the calibration particle to automatically determine the conversion factor between pixel units and physical units under the actual measurement conditions. The calibration process itself adapts to the ambient temperature and dispersion medium viscosity, making the measurement system self-adjusting without external temperature control or measurement
3Adaptability or versatility
If flow velocity correction is applied to measure particle size in flow fields, then measurement versatility is improved, but measurement precision deteriorates due to difficulty in measuring flow velocity component
Solution Approach 1:
The calibration particle acts as a mediator for flow velocity measurement. By tracking the mean-square displacement of the calibration particle (which has known properties) in the flow field, the system can indirectly determine the flow velocity component without requiring direct flow measurement equipment. The calibration particle's motion serves as a reference to separate flow effects from Brownian motion effects
Solution Approach 2:
The system uses the measured mean-square displacement of the calibration particle to feedback-correct the flow velocity component. By comparing the observed displacement with the expected displacement based on the calibration particle's known size and Brownian motion characteristics, the system iteratively determines and corrects for the flow velocity, improving measurement precision in flow fields
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 precise particle size measurement in various mediums without the need for extensive equipment or temperature control, improving accuracy and efficiency by using calibration data to derive particle sizes from pixel-based displacements.
Implementation Method 1
the particle is irradiated with laser light for observation of a condensing point (hereinafter referred to as a bright point) of scattered light from the particle by an optical system and the particle size is calculated from Brownian motion of each particle
Implementation Method 2
observation of a condensing point (hereinafter referred to as a bright point) of scattered light from the particle
Data Source
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AI summary
To easily calibrate, using a calibration particle, a measuring device configured to capture an image of a target object such as a target particle. An image analyzer (21) acquires multiple images obtained at a predetermined time interval Δt, (a) specifies the mean-square displacement ΔMS-cal of a bright point of a calibration particle based on the displacement, in terms of a pixel unit, of the bright point of the calibration particle in the multiple images in a calibration mode, and (b) specifies the mean-square displacement ΔMS of a bright point of the target particle based on the displacement, in terms of the pixel unit, of the bright point of the target particle in the multiple images in a measuring mode. A particle size analyzer (22), (c) in the analysis mode, derives the particle size d of the target particle from the mean-square displacement ΔMS of the bright point of the target particle based on the mean-square displacement ΔMS-cal of the bright point of the calibration particle and the particle size dcal of the calibration particle.