Photonics Spectra - March 2011

or more at a rate of about 20 particles per second.

The device’s performance could be improved by quieter diode lasers, better locking electronics and improvements in the manufacturing of the high-reflectivity mirrors. Shane Murphy noted that future needs include making the device smaller and more portable. There also is a desire to shift to a laser with a shorter wavelength than that of the current red source.

“One of the real big interests scientifically right now is what organics do, and they’re going to absorb down in the blue wavelengths. They’re not going to do anything in the red,” he said.

Advances in laser technology mean that this switch can be accomplished with a change of the laser diode source. Murphy said that a smaller version of the device will be ready for deployment this year in Barbados to measure dust blown from the Sahara Desert.

Commercially available photonics-
based particle analysis includes sizing
via laser scattering and probing via pho-
toacoustics, which involves the rapid
heating of particles and detection of the
sounds generated. The technique produces
information about particle composition,
since both heating and cooling are influ-
enced by particle makeup.

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