New technique measures ultrashort laser pulse...( Lasers that emit ultrashort pulses of...)

Lasers that emit ultrashort pulses of light are used for numerous applications including micromachining, microscopy, laser eye surgery, spectroscopy and controlling chemical reactions. But the quality of the results is limited by distortions caused by lenses and other optical components that are part of the experimental instrumentation.

To better understand the distortions, researchers at the Georgia Institute of Technology developed the first device to directly measure complex ultrashort light pulses in space and time at and near the focus. Measuring the pulse at the focus is important because thats where the beam is most intense and where researchers typically utilize it. Knowing how the light is distorted allows researchers to correct for the aberrations by changing a lens or using a pulse shaper or compressor to manipulate the pulse into the desired form.

Researchers have always measured the pulse immediately as it exited the laser, so they didnt realize the extent to which the pulse became distorted by the time it reached the focus after traveling through the optics and lenses in the system, said Rick Trebino, a professor in the Georgia Institute of Technologys School of Physics and Georgia Research Alliance Eminent Scholar in Ultrafast Optical Physics.

The device was described in a presentation at the Conference on Lasers and Electro-Optics on May 8. This research was funded by the National Science Foundation and published in the August 2007 issue of the journal Optics Express.

It is difficult to measure ultrashort pulses because they typically last between a few femtoseconds and a picosecond, which are 10-15 and 10-12 of a second, and faster than the response time of the fastest electronics.

The light comes out as a train of extremely short bursts. The laser crams all of the energy of a continuous laser into a few femtoseconds, which creates really intense laser pulses, said Pam Bowla
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