odditiesoflife:

The Art of the Perfect Wave

These amazing images of waves are the work of two different photographers. The first set is by David Orias. He relies on slow shutter speeds and the perfect light of sunrise or sunset to capture these waves off the coast of California.

The second set is by Pierre Carreau. He shoots waves with a variety of high speed cameras using various macro and wide angle lenses. These waves appear more like glass sculptures than liquid.

paleoillustration:

The Pinhole Eye of the Nautilus, by Marc Gosselin:

“The Nautilus is the only animal on the planet with pinhole eyes.”

spaceplasma:

Bill Nye: The Science Guy

spaceplasma:

Dye laser

A dye laser is a laser which uses an organic dye as the lasing medium, usually as a liquid solution. Compared to gases and most solid state lasing media, a dye can usually be used for a much wider range of wavelengths. The wide bandwidth makes them particularly suitable for tunable lasers and pulsed lasers. Moreover, the dye can be replaced by another type in order to generate different wavelengths with the same laser, although this usually requires replacing other optical components in the laser as well.

Dye lasers were independently discovered by P. P. Sorokin and F. P. Schäfer (and colleagues) in 1966.

The dyes used in these lasers contain rather large organic molecules which fluoresce. The incoming light excites the dye molecules into the state of being ready to emit stimulated radiation, the singlet state. In this state, the molecules emit light via fluorescence, and the dye is transparent to the lasing wavelength. Within a microsecond, or less, the molecules will change to their triplet state. In the triplet state, light is emitted via phosphorescence, and the molecules absorb the lasing wavelength, making the dye opaque. Liquid dyes also have an extremely high lasing threshold. Flashlamp pumped lasers need a flash with an extremely short duration, to deliver the large amounts of energy necessary to bring the dye past threshold before triplet absorption overcomes singlet emission. Dye lasers with an external pump laser can direct enough energy of the proper wavelength into the dye with a relatively small amount of input energy, but the dye must be circulated at high speeds to keep the triplet molecules out of the beam path.

In laser medicine these lasers are applied in several areas, including dermatology where they are used to make skin tone more even. The wide range of wavelengths possible allows very close matching to the absorption lines of certain tissues, such as melanin or hemoglobin, while the narrow bandwidth obtainable helps reduce the possibility of damage to the surrounding tissue. They are used to treat port-wine stains and other blood vessel disorders, scars and kidney stones. They can be matched to a variety of inks for tattoo removal, as well as a number of other applications.

In spectroscopy, dye lasers can be used to study the absorption and emission spectra of various materials. Their tunability, (from the near-infrared to the near-ultraviolet), narrow bandwidth, and high intensity allows a much greater diversity than other light sources. The variety of pulse widths, from ultra-short, femto-second pulses to continuous-wave operation, makes them suitable for a wide range of applications, from the study of fluorescent lifetimes and semiconductor properties to lunar laser ranging experiments.

Image Credit: Warsash Scientific

spaceplasma:

Perfectly doped quantum dots yield colors to dye for

Quantum dots are tiny nanocrystals with extraordinary optical and electrical properties with possible uses in dye production, bioimaging, and solar energy production. Researchers at the University of Illinois at Chicago have developed a way to introduce precisely four copper ions into each and every quantum dot.

The introduction of these “guest” ions, called doping, opens up possibilities for fine-tuning the optical properties of the quantum dots and producing spectacular colors.

“When the crystallinity is perfect, the quantum dots do something that no one expected—they become very emissive and end up being the world’s best dye,” says Preston Snee, assistant professor of chemistry at UIC and principal investigator on the study.

The results are reported in the journal ACS Nano, available online in advance of print publication. Incorporating guest ions into the crystal lattice can be very challenging, says UIC graduate student Ali Jawaid, first author of the paper.

Controlling the number of ions in each quantum dot is tricky. Merely targeting an average number of guest ions will not produce quantum dots with optimal electrical and optical properties.

Jawaid developed a procedure that reliably produces perfect quantum dots, each doped with exactly four copper ions. Snee believes the method will enable them to substitute other guest ions with the same consistent results.

“This opens up the opportunity to study a wide array of doped quantum dot systems,” he said.

Donald Wink and Leah Page of UIC and Soma Chattopadhyay of Argonne National Laboratory also contributed to the study.

Credit: Jeanne Galatzer-Levy