Institute for Atmospheric and Climate Science

Impressions from the Laboratory

A levitated particle is easily seen by eye or a standard photo camera when illuminated by a laser beam.

Above, you see a micrometer sized aqueous aerosol particle levitated in our balance and illuminated by the light of a Nd:YAG Laser at 532 nm. It is seen with the balance not placed in its chamber, but through the central hole in the upper endcap electrode where usually the gas stream inlet is located.

The next picture shows a particle trapped in the balance with the balance placed in its chamber. In a scattering plane 90° to the incoming laser beam theres is a light reflecting screen placed. One of the windows in the glass chamber is a lens placed such that the particle is placed in its focal spot. On the screen you see an interference pattern (Two-dimensional angular scattering pattern) arising from scattered light of a liquid (spherical) particle.

This angular scattering pattern while change drastically when a liquid aqueous solution particle becomes solid upon drying (efflorescence). Here you can see a little movie of the scattering pattern taken with a video camera placed where the screen is located in the picture above.

Movie 2-D angular scattering pattern
Movie 2-D angular scattering pattern

The following picture gives an impression on how the chamber is placed on the optical table and how the laser is steered to illuminated the particle.

And finally we show a view on the different monitors connected to the computers used for controlling the experiment and for data acquisition.


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© 2014 ETH Zurich | Imprint | Disclaimer | 12 February 2007