Sunday, May 11, 2008
Search for Aliens Just Got 100 Times More Powerful
New laser to aid searches for Earthlike planets
Scientists at the University of Konstanz in Germany and the National Institute of Standards and Technology (NIST), USA have demonstrated an ultrafast laser that offers a record combination of high speed, short pulses and high average power.
This group has also shown that this type of laser, when used as a frequency comb could boost the sensitivity of astronomical tools searching for other Earthlike planets as much as 100 fold.
What are frequency combs? We will let NIST explain: "An optical "frequency comb" is a very precise tool for measuring different colors—or frequencies—of light. The technology, made possible by recent advances in ultrafast lasers, can accurately measure much higher frequencies than any other tool. Frequency combs are already widely used in metrology laboratories and physics research, and they are starting to become commercially available.
Optical frequency combs rely on the relationship between time and frequency. NIST scientists start with lasers that emit a continuous train of very brief, closely spaced pulses of light containing a million different colors. The properties of the light over time are converted to frequency numbers to make what looks like a comb."
The timing between pulses determines the spacing between the teeth of the frequency comb. The faster the pulse repetition rate, the wider the spacing between the teeth, making each individual tooth easier to identify.
The small-sized laser developed by the joint team emits 10 billion pulses per second, each lasting about 40 femtoseconds (quadrillionths of a second), with an average power of 650 milliwatts. The new laser produces pulses 10 times more often than a standard NIST frequency comb while producing much shorter pulses. The new laser is also 100 to 1000 times more powerful than typical high-speed lasers, producing clearer signals in experiments.
There are some interesting applications to which this new technology could be put. Frequency combs have already dramatically simplified and improved the accuracy of frequency metrology. They also are making it possible to build precise atomic clocks. These new ultra-precise frequency combs could enable progress in many other advanced fields of science such as detection of toxic biochemical agents, studies of ultrafast dynamics, quantum computing, in synchronization of advanced telecommunications systems, remote detection and range measurements for manufacturing or defense applications, remote sensing of gases for medical or atmospheric studies, on-the-fly precision control of high-speed optical communications, and more.
Apart from these, one exciting prospect is the increased ability to explore planets orbiting distant stars. Why?
In order to identify the presence of a planet orbiting stars, astronomers look for slight variations in the colors of starlight. These color variations occur due to the small wobbles induced in the star’s motion as the orbiting planet travels back and forth.
Currently, astronomers’ instruments frequency standards calibrations that are limited in spectral coverage and stability. Current instruments can detect, at best, a wobble of about 1 meter per second. Lasers used as frequency combs could be more accurate calibration tools, helping to pinpoint even smaller variations in starlight caused by small planets.
The team that developed it says it is pursuing the possibility of testing such a laser at a ground-based telescope or launching a comb on a satellite or other space mission.
The application of frequency combs to planet searches is of international interest and involves a number of major institutions such as the Max-Planck Institute for Quantum Optics and Harvard Smithsonian Center for Astrophysics.
More information here @ NIST
Via: Next Big Future
See also: John H Hall Nobel Lecture on Optical Frequencies (2005)
Scientists at the University of Konstanz in Germany and the National Institute of Standards and Technology (NIST), USA have demonstrated an ultrafast laser that offers a record combination of high speed, short pulses and high average power.
This group has also shown that this type of laser, when used as a frequency comb could boost the sensitivity of astronomical tools searching for other Earthlike planets as much as 100 fold.
What are frequency combs? We will let NIST explain: "An optical "frequency comb" is a very precise tool for measuring different colors—or frequencies—of light. The technology, made possible by recent advances in ultrafast lasers, can accurately measure much higher frequencies than any other tool. Frequency combs are already widely used in metrology laboratories and physics research, and they are starting to become commercially available.
Optical frequency combs rely on the relationship between time and frequency. NIST scientists start with lasers that emit a continuous train of very brief, closely spaced pulses of light containing a million different colors. The properties of the light over time are converted to frequency numbers to make what looks like a comb."
The timing between pulses determines the spacing between the teeth of the frequency comb. The faster the pulse repetition rate, the wider the spacing between the teeth, making each individual tooth easier to identify.
The small-sized laser developed by the joint team emits 10 billion pulses per second, each lasting about 40 femtoseconds (quadrillionths of a second), with an average power of 650 milliwatts. The new laser produces pulses 10 times more often than a standard NIST frequency comb while producing much shorter pulses. The new laser is also 100 to 1000 times more powerful than typical high-speed lasers, producing clearer signals in experiments.
There are some interesting applications to which this new technology could be put. Frequency combs have already dramatically simplified and improved the accuracy of frequency metrology. They also are making it possible to build precise atomic clocks. These new ultra-precise frequency combs could enable progress in many other advanced fields of science such as detection of toxic biochemical agents, studies of ultrafast dynamics, quantum computing, in synchronization of advanced telecommunications systems, remote detection and range measurements for manufacturing or defense applications, remote sensing of gases for medical or atmospheric studies, on-the-fly precision control of high-speed optical communications, and more.
Apart from these, one exciting prospect is the increased ability to explore planets orbiting distant stars. Why?
In order to identify the presence of a planet orbiting stars, astronomers look for slight variations in the colors of starlight. These color variations occur due to the small wobbles induced in the star’s motion as the orbiting planet travels back and forth.
Currently, astronomers’ instruments frequency standards calibrations that are limited in spectral coverage and stability. Current instruments can detect, at best, a wobble of about 1 meter per second. Lasers used as frequency combs could be more accurate calibration tools, helping to pinpoint even smaller variations in starlight caused by small planets.
The team that developed it says it is pursuing the possibility of testing such a laser at a ground-based telescope or launching a comb on a satellite or other space mission.
The application of frequency combs to planet searches is of international interest and involves a number of major institutions such as the Max-Planck Institute for Quantum Optics and Harvard Smithsonian Center for Astrophysics.
More information here @ NIST
Via: Next Big Future
See also: John H Hall Nobel Lecture on Optical Frequencies (2005)
Labels: Astronomy
PermaLink - Search for Aliens Just Got 100 Times More Powerful posted by Ecacofonix : 6:51 AM
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