Color It Anything …first continuous dye laser gives science tunable tool (Apr, 1971)
Color It Anything …first continuous dye laser gives science tunable tool
By ARTHUR FISHER / Group Editor, Science and Engineering
I watched the familiar cold blue light of an argon laser lance into the center of a shiny stainless-steel device festooned with lengths of plastic piping. My host, Dr. Otis G. Peterson of Kodak Research Laboratories in Rochester, N. Y., made a few final adjustments of the vernier controls. Then he said “There it goes.”
And there it was: a steady, yellow-orange beam of light emerging from the other end of the device. I had just seen the world’s first continuous tunable dye laser lase.
In a dye laser, a water solution of an organic dye (here rhodamine 6G) is circulated through a precisely shaped optical cavity. The material lases when it is stimulated by the right kind of external “pumping” light. Lasing occurs when the dye molecules shift from one energy state to another, accompanied by the release of energy in the form of light. But previous tunable dye lasers lost internal energy when large numbers of molecules quickly got stuck in the triplet state, which absorbs light, so that laser output was held to pulses lasting only millionths of a second.
Dr. Peterson and his colleagues, Sam A. Tuccio and Dr. Benjamin B. Snavely, overcame this difficulty and several others, partly by adding a soap-like substance to the dye solution; this quenches internal losses.
The new continuous laser is tunable from about 5,500-6,500 angstroms, or roughly from greenish-yellow to red, but the Kodak team expects that soon it will be made tunable over the whole visible spectrum.
What do you do with a tunable dye laser? Perform improved spectroscopic research, such as identifying impurities in the atmosphere. Investigate photochemical reactions in plants, animals, and chemical systems like smog. Set up scintillating optical displays. Expand communications facilities by providing the optical equivalent of broad-band FM.
Dr. Peterson pointed out that organic dyes are much cheaper than other lasing materials such as rubies and special glasses, and can now be tuned to cover many of their wavelengths. The future, he said, may see the mass production of inexpensive lasers.