The technique, called Serial Time-Encoded Amplified imaging (STEAM), is based on supercontinuum laser pulses (ie., ultrabroad bandwidth pulses). The pulses are propagated to a bidimensional colour matrix by two optical elements. Then, the beam lights the samples: a part of it is reflected by the sample, depending on the dark and light areas of the illuminated point, and the reflections come back through the same way. Since the propagation of the different colours of the pulse is so regular, the range of reflected colours have detailed spatial information about the sample.
According to Bahram Jalali, professor of the University of California and director of this research, "the light points reflects their assigned wavelength, but the dark ones do not, so when the bidimensional rainbow is reflected in the object, the image is copied over the pulse spectrum". The pulse goes back through the optical dispersive system and is converted once more in a single spot, with the image saved in a serie of distributed colours; then, the beam goes through a dispersive fiber (ie., an optical fiber with different velocity limits for each colour). As result, the red part of the spectrum travels at different from the blue, they get separated and finally they arrived at different moments. The signal is then detected by a photodiode and the image is reconstructed. As a result of this technique, an improvement of the speed of images recording is improved (it is the same as the laser repetition rate) with a very high spatial resolution. This could find a wide variety of applications, such as pictures of blood or even the internal structure of the cells.
Monday, June 29, 2009
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