Size measurement of microdroplets using light scattering

1Current Research – Size measurements of microdroplets using light scattering

Evaluation of droplet size in inkjet systems is necessary for…• Printing technology• Manufacturing “functional droplets”

(→refer to “Dynamics of colliding microdroplets”)

Inkjets

10µm in radius 10m/s in velocity 100,000

droplets/sec

Measuring such a small yet fast particles requires special skills

2Current Research – Size measurements of microdroplets using light scattering

Previous methodsMicroscopic Picture Flow Rate Method

Disadvantage;Intrinsic error of about a wavelength resides at the interface

~10µm Counting the amount of

time it takes to produce certain amount of droplets

Disadvantage;Takes a long time.Cannot measure directly; inapplicable to size-changing phenomena

3Current Research – Size measurements of microdroplets using light scattering

Light ScatteringRayleigh Scattering　（ Particles smaller than the wavelength ）

Mie Scattering　（ Particles larger than the wavelength ）

large

small

The interference pattern changes with size

4Current Research – Size measurements of microdroplets using light scattering

He-Ne Laser

Lens

CCD

Experiment

Theoretical analysis of the interference position led to a simple method enabling size measurement with 0.3% error.

Techniques and skills• IT

Microsoft Office Suite, gnuplot, ImageJ• Programming

Java• Techniques

Light scattering, image processing, etc.• Equipment

Oscilloscope, function generator, etc.

5Current Research – Size measurements of microdroplets using light scattering