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A method for scattering angle calibration in the rainbow region using a droplet stream
Optics Express
|November 11, 2022
Summary
A new calibration method for rainbow refractometry improves measurement accuracy. This technique precisely relates detector pixels to scattering angles, enhancing droplet size and refractive index characterization.
Area of Science:
- Optical physics
- Metrology
Background:
- Rainbow refractometry is an emerging technique for characterizing droplet size and refractive index.
- Accurate measurement relies on precise quantification of scattering angle versus detector pixel.
Purpose of the Study:
- To introduce a novel calibration method for rainbow refractometry using a monodisperse droplet stream.
- To estimate the achievable accuracy of this calibration method.
Main Methods:
- Derived a linear pixel-to-angle relationship for calibration.
- Proposed a calibration procedure based on global fitting of data to the theoretical rainbow signal.
- Validated the method using simulations, experiments, and shadowgraphy.
Main Results:
- Demonstrated a feasible calibration method with high accuracy.
- Achieved maximum absolute errors of 0.032° for intercept and 3.9E-5°/pixel for slope.
- Resulting uncertainties in diameter and refractive index were approximately 0.67% and 2.8 × 10-4.
Conclusions:
- The novel calibration method significantly enhances the accuracy of rainbow refractometry.
- This method provides reliable characterization of droplet properties.
- The validated approach offers a robust solution for precise optical measurements.
