Refractive-index measurements for the correction of particle sizing methods

Area of Science:

• Optical physics
• Fluid dynamics
• Materials science

Background:

• Optical particle sizing methods often require the liquid's refractive index.
• Literature data is insufficient for unknown liquids or dynamic changes (heating, reactions).
• Accurate refractive index measurement is essential for precise particle size determination.

Purpose of the Study:

• To present a novel method for determining the real part of the refractive index of liquid droplets.
• To enable accurate particle sizing when refractive index data is unavailable or changing.
• To demonstrate the method's application in dynamic environments like burning droplets.

Main Methods:

• Utilizing the angular position shift of the first-order rainbow.
• Analyzing the relationship between rainbow position and the liquid's refractive index.
• Applying the method to streams of burning droplets.

Main Results:

• Successfully determined the real part of the refractive index of droplets.
• Demonstrated the method's efficacy on burning droplet streams.
• Provided a practical approach for in-situ refractive index measurement.

Conclusions:

• The presented rainbow shift method is effective for measuring droplet refractive index.
• This technique is vital for accurate optical particle sizing in dynamic and unknown liquid scenarios.
• The method offers a valuable tool for research involving liquid droplets, especially in combustion or chemical processes.