The Miracles of Laser Technology

[Divinity]

A femtosecond = one millionth of a nanosecond or 10 -15 of a second and is a measurement sometimes used in laser technology.


CHIRPED-pulse amplification strikes again.

Using it in a high-peak-power mode, Laboratory scientists produced first the 100-terawatt laser and then the petawatt laser, opening up new opportunities for applying laser-matter interactions. Now a Livermore team has won an R&D 100 Award for applying chirped-pulse amplification in a high-average-power mode for cutting and machining materials. The system was developed for disassembling nuclear weapons components, but it has many other uses as well.

The team, led by Brent Stuart, illustrates Livermore's collaborative nature by combining research and development expertise from Laser Programs and Defense and Nuclear Technologies Directorates.

From Demilitarization to Dentistry
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By ionizing the material being cut--removing it atom by atom--the cutting technique allows precise machining of everything from steel to tooth enamel to very soft materials like heart tissue. Each pulse of this machining system is extremely short, lasting just 50 to 1,000 femtoseconds (or quadrillionths of a second). These ultrashort pulses are too brief to transfer heat or shock to the material being cut, which means that cutting, drilling, and machining occur with virtually no damage to surrounding material. Furthermore, this revolutionary laser can cut with extreme precision, making hairline cuts in thick materials along a computer-generated path.

In dentistry applications, the thermal nature of the conventional laser ablation process can heat and crack a tooth and produce a random-shaped hole within a large area of collateral damage. In contrast, at the same ablation rate, Livermore's new laser precisely removes the material and leaves the surrounding areas in their original state (see a and b of the figure, below).

The ultrashort-pulse laser represents a major advancement in cutting technology. Conventional lasers, diamond saws, and water jets are used commercially for a variety of cutting and machining applications. But each one has drawbacks. None of them can achieve the precision of the femtosecond laser machine tool (0.1 millimeters), and most of them damage surrounding material to varying degrees. Because of these shortcomings, no commercial cutting system can be used on the range of materials or applications of Livermore's new tool.

Industrial lasers, which melt and boil material to remove it, are often used in precision cutting. The heat and shock cause considerable damage to the area surrounding the cut that can range from changes in the grain structure to cracking. The damage may extend from a few micrometers to several millimeters from the cut, depending on the properties of the material, the laser pulse duration, and whether a cooling method is used. Very tiny structures only a few tens of micrometers in size, such as biological tissue or semiconductor devices, are extremely fragile. Even the slightest thermal stress or shock creates intolerable collateral damage.

These conventional cutting methods also leave slag around the cut. When material is vaporized, some of it is deposited on the walls or upper surface of the cut. This residue reduces the quality of the cut and the efficiency of the cutting system.

With each short pulse of the Laboratory's new laser cutter, material is heated to temperatures far beyond the boiling point, producing an ionized plasma, while leaving surrounding material cool. The pulse deposits its energy so quickly that it does not interact at all with the plume of vaporized material, which would distort and bend the incoming beam and produce a rough-edged cut. The plasma plume leaves the surface very rapidly, ensuring that it is well beyond the cut edges before the arrival of the next laser pulse. And because only a very thin layer of material is removed during each pulse of the laser, the cut surface is very smooth and does not require subsequent cleanup (see c and d of the figure, below).

Removal of minimal amounts of material makes this new cutting system useful for processing extremely valuable or hazardous materials. If the cutting is done in a vacuum, better than 95% of the removed material can be recovered.
Another Livermore team is building a high-powered femtosecond machining system for the Department of Energy's Y-12 Plant at Oak Ridge, Tennessee, one of this country's primary manufacturers of nuclear weapon components. A second unit at Livermore will be used as engineering support to the Y-12 unit. The high precision of this cutter will maximize the plant's ability to reuse high-value components and minimize the amount of waste generated during the cutting process.

Livermore is studying the use of the Femtosecond Laser to machine high explosives for experiments at its High Explosives Applications Facility. Because so little energy or mechanical shock is transferred to the part being machined, the team has demonstrated that materials such as high explosives or parts containing high explosives can be cut without danger of detonation. The team is also working on the design of a system for demilitarizing chemical weapons.

Other potential applications abound. Using the laser as a surgical tool for soft tissue has already been discussed in Science & Technology Review (October 1995). A semiconductor device producer is exploring the use of the unit for cutting high-value semiconductor wafers. Other major U.S. manufacturers are looking into incorporating femtosecond machining systems into their production lines. In manufacturing, new materials are constantly appearing, and the features on all kinds of devices are becoming smaller and smaller. The femtosecond machining system may be the most effective way to respond to both challenges with its high precision on all materials regardless of composition.

--Katie Walter

https://www.llnl.gov/str/Stuart.html

[Divinity]

My point is: if we have known about femtobiology/femtochemistry and femtolasers for this long, why is it that the standards physics model informs us that 'nothing travels faster than the speed of light'?

Divinity



http://physicsworld.com/cws/article/indepth/34774

Jul 1, 2008

A quantum renaissance

Physicists can now routinely exploit the counterintuitive properties of quantum mechanics to transmit, encrypt and even process information. But as Markus Aspelmeyer and Anton Zeilinger describe, the technological advances of quantum information science are now enabling researchers to readdress fundamental puzzles raised by quantum theory


Excerpt:

Both fundamental quantum experiments and quantum information science owe much to the arrival of the laser in the 1960s, which provided new and highly efficient ways to prepare individual quantum systems to test the predictions of quantum theory. Indeed, the early development of fundamental quantum-physics experiments went hand in hand with some of the first experimental investigations of quantum optics.

[Divinity]

Thank you Lizzie for this link:

http://www.ust.caltech.edu/press/index.html

ULTRAFAST Science and Technology
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This company are pursuing Femtobiology and Femtochemistry - the link explains some of their Research Highlights.

Indeed, this is the way forward and I've discovered today that it's led to a whole new branch of Science called Quantum Information Science.

Divinity

[Divinity]

http://www.ust.caltech.edu/press/theory.html#paper3

This is just ONE of the Abstracts from Caltech...to signify how advanced these guys are in this field:

Ultrafast electron diffraction: Oriented molecular structures in space and time
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The technique of ultrafast electron diffraction allows direct measurement of changes which occur in the molecular structures of isolated molecules upon excitation by fs laser pulses. The vectorial nature of the molecule-radiation interaction also ensures that the orientation of the transient populations created by the laser excitation is not isotropic. Here, we examine the influence on electron diffraction measurements - on the fs and ps timescales - of this induced initial anisotropy and subsequent inertial (collision-free) molecular reorientation, accounting for the geometry and dynamics of a laser-induced reaction (dissociation). The orientations of both the residual ground-state population and the excited- or product-state populations evolve in time, with different characteristic rotational dephasing and recurrence times due to differing moments of inertia. This purely orientational evolution imposes a corresponding evolution on the electron scattering pattern, which we show may be similar to evolution due to intrinsic structural changes in the molecule, and thus potentially subject to misinterpretation. The contribution of each internuclear separation is shown to depend on its orientation in the molecular frame relative to the transition dipole for the photoexcitation; thus not only bond lengths, but also bond angles leave a characteristic imprint on the diffraction. Of particular note is the fact that the influence of anisotropy persists at all times, producing distinct differences between the asymptotic "static" diffraction image and the predictions of isotropic diffraction theory.

[Divinity]

I know very little about lasers except that they seems to work on the ON/OFF principle, i.e. pulsed Light which is switched on and off so quickly that even heat transfer cannot take place (in some cases). What a magnificent concept! If "each pulse is short, i.e. 50-1000 femtoseconds", what is actually making it go on and off so fast? Is this wave or particle technology?

And does this technology go some way to help prove the Plasma/Electric Universe?

If we are able to invent such a mechanical piece of equipment, how come this technology doesn't extend into other practical areas of life, i.e. possible free energy/pollution-free manufacturing/engineering, etc.?

Divinity

[lizzie]

Divinity said: The contribution of each internuclear separation is shown to depend on its orientation in the molecular frame relative to the transition dipole for the photoexcitation; thus not only bond lengths, but also bond angles leave a characteristic imprint on the diffraction. Of particular note is the fact that the influence of anisotropy persists at all times, producing distinct differences between the asymptotic "static" diffraction image and the predictions of isotropic diffraction theory.

It sounds as if the following author is describing just such phenomena.

Plasma is the “four state of matter,” but beyond matter, there is the “invisible world” which appears to operate according to the “laws of vibration.”

http://lightmind.com/library/hempel/sound-current.html

The motion of any particle [or pulse] will be a succession of waves...but in a vibration the restoring force is exactly proportional to the distance the particle has moved from its position of equilibrium.” This is known in physics as the law of Pythagoras. The implication of this law is that “the motion of every particle will be of the same kind, whatever the structure to which it belongs.”

Philosopher David Loy in Nonduality explains that "...if there were only one thing [the multidimensional harmonic wave], with nothing 'outside' it, then that one would not be aware of itself as one. The phenomenological experience would be of no thing/nothing."

The empty (not modulated) vacuum (void) is the medium full of numerous unrealized tendencies for action in which the actualization of potentialities takes place.

Fourier's Theorem is derived from the law of Pythagoras and determines the fundamental pulse of complex waveforms by analyzing spatial frequencies, amplitudes and phase relations. This concept of natural free multiples arising from zero wave-forms or the void has been noted by physicist Jean Charon.

This, in turn, may imply that if entropy grows in the 'material' world, then in the world of electrons precisely the opposite force might grow, the force of negentropy.

Woodhouse describes the harmonic power from measuring rhythmic vibrations that arises from the lack of beats, from zero in scalar electromagnetics: “by canceling out [forces of repulsion] through appropriate (though variable) phase modulation - we literally create a field of gravitational potential.”

There would be no life, and therefore no action in aggregated matter, had the latent negative force [the nothingness measured by music theory] been left out...The evolution of power from the latent condition...proves the 'connection link' between celestial and terrestrial, the infinite and the finite.

[Divinity]

Physicists Steer Electrons With Laser Pulses

ScienceDaily (Nov. 13, 2008) — Theoretical physicist Uwe Thumm and his colleagues Feng He and Andreas Becker not only work with some of the smallest molecules in the universe, but they now have found a way to control the motion of the molecules' building blocks, electrons and nuclei.

Thumm is a professor of physics at Kansas State University. Feng is a research associate at the K-State physics department, and Becker is a professor at the University of Colorado in Boulder. The collaborators have found a way to steer the movement of electrons in a hydrogen molecule using ultrafast laser pulses. These pulses are so short that their duration is measured in attoseconds -- that's one billionth of a billionth of a second.

In a recent research paper, the three collaborators explained how attosecond laser pulses can be used to direct the motion of an electron inside a hydrogen molecule, and what the measurable consequences of this control over the electron would be. The paper appears this month in Vol. 101 of The Physical Review Letters.

As theoretical physicists, Thumm and his colleagues do not perform experiments, but instead simulate the outcome of present and future experiments by developing mathematical models. These models explain the nature of atoms, molecules, light and their interactions in terms of mathematical equations that are solved with the help of powerful computers.

The researchers' model describes experiments that are currently being performed at various laboratories worldwide, including the J.R. Macdonald Laboratory at K-State.

For the past few years, Thumm and his colleagues studied what happens with the hydrogen molecular ion when it interacts with short laser pulses. They used hydrogen because it's the simplest molecule, although they have now extended their research toward the imaging and control of the much faster moving electrons.

The hydrogen molecular ion has two protons and just one electron that "glues" them together. A few years ago, by performing computer simulations, they found that laser pulses can control the motion of the protons by setting them in motion or slowing them down.

The researchers use a first ultrafast laser to pump the molecule with infrared pulses. The protons vibrate and move apart slowly, but the electron still tries to hang on. The second part of their model uses the laser to probe the particles with a second delayed light pulse to see what happens when the electron fails to keep the protons glued together. The infrared laser pulses create an electric field that puts a force on the electron. Eventually, Thumm said, the electron has to choose which proton it will stick with.

Thumm and his colleagues were surprised to find that for certain laser pulses the electron can move in the opposite direction from what they anticipated.

"Our naive expectation was that the electron would follow the laser electric force," Thumm said. "That's what other simulations predicted, and they agree with classical physics and common intuition."

For instance, if you're pulling on a shopping cart, the cart will move in the direction of the force -- in this case, toward you. But at the quantum level, the rules are different.

The researchers found that sometimes the electron moves in the direction of the force, but sometimes not. Thumm, He and Becker found that the electron picks the proton on the left or the one of the right depending on the intensity of the laser pulse. Knowing which intensity will make the electron move to the left or the right gives physicists the ability to steer the electrons by setting the laser pulse to a specific intensity.

Thumm said this finding is not only a contribution to basic physics research, but it also could help chemists better understand and possibly control chemical reactions.

"We would like to see a 'molecular movie' that shows the redistribution of electrons in time -- within attoseconds -- during a chemical reaction," he said. "It would promote our understanding of basic processes that eventually enable life: electrons bind atoms to simple molecules, such as the hydrogen molecule or water. Through many chemical reactions, these simple molecules react with each other and eventually form huge bio-molecules that make life, as we know it, possible."

One possible commercial application of the finding, Thumm said, could be helping companies become more efficient in producing a desired chemical compound while minimizing unwanted byproducts in the reaction.

http://www.sciencedaily.com/releases/20 ... 181426.htm