inventing the light fantastic: ideas behind laser born long before device itself. - long distance laser level

by:UMeasure     2020-03-27
inventing the light fantastic: ideas behind laser born long before device itself.  -  long distance laser level
Slightly] Illustrations
After nine months of in-depth research, the physicist Theodore Maiman finally ushered in the glory.
In the spring of 1960, Maiman has been working with assistant Irnee d. Haenens at Hughes Research Lab in Malibu, California.
, To see if he can produce a new type of light by emitting radiation with a powerful photographic flash to spray the atiny pink ruby crystal. Using off-the-
Maiman is competing with six other research teams who are scrambling to produce a high-intensity pencil
Visible thin beam
In the arrangement of energy and Valley, sound waves are perfectly matched.
Other scientists have declared that a pink ruby cannot produce such radiation.
But Ma man does not think so.
On May 16, 1960, he and d Haenens watched their oscilloscope and they raised the voltage to a flashlight revolving around a small rubyrod.
The intensity rose sharply, followed by a sharp drop, suggesting that the ruby did send out a bright, coherent light pulse.
Maiman, d Haenens and several colleagues excitedly decided to repeat the experiment and check the beam as it hits the whiteboard screen.
D. Haenens is in color
It was blind at first and could not see the color of the crystal.
However, when the voltage of the flash rises, the light pulse from rubyrod becomes so strong that other people's eyes that are sensitive to the normal red color are too dazzling to record the signal.
Only dehaines can see the glorious horseshoe.
This shows that the team has created a powerful beam of light. -
D. Haenens recalled in an interview with the American Institute of Physics 1985 that light amplification was achieved.
This is indeed a new vision.
D. Haenens witnessed the birth of the laser.
After five years, the importance of laser in daily life may be second only to computers.
From welding the separated retina to telephone transmission around the world, from the core of each CD player to the treatment of life --
Thelaser implies itself in almost every technical aspect of modern society.
Low frequent use by Microbiology
Push bacteria, cells and even DNA with laser as tweezers.
Doctors send laser light through flexible cables to kill cancer cells, crush kidney tissue and destroy other unwanted growth in the human body.
On a more cosmic scale, the laser that shoots into space makes the ground-
Telescope for making Crystal
A clear image of the sky.
Like many important discoveries in the 20 th century physical science, Einstein's laser can be traced back to Einstein.
Although he did not have the concept of laser-like devices in 1916, he has a lasting interest in the interaction between light and matter.
In those days, many scientists studying light were working on both spontaneous absorption and spontaneous emission.
Spontaneous absorption occurs when light of the right energy shines on the atom.
The outermost electron of an atom absorbs energy (
In the form of photons--
Particles of light)
Jump spontaneously to a higher level of energy.
However, in the absence of external energy, the electronics are like couch potatoes ---
In the process, they return to the lowest possible energy and spit out a photon.
The electron absorbs photons at about the same speed, and it glows spontaneously.
The visible surface of the Sun, the filament of the bulb and the wick of the burning candle all glow due to spontaneous radiation.
But Einstein showed that in order to be consistent with quantum theory and thermodynamics, there must also be another type of emission ---
Laid the foundation for the development of laser.
Einstein believes that if light strikes an atom that can stimulate electrons, it can also force the already excited electron to radiate light and drop to a lower energy level.
Imagine that a bunch of atoms are excited because electrons absorb photons.
Stimulate these atoms with a secondary light pulse with exactly the same energy as the original light absorbed by the electron.
Einstein pointed out that the second pulse prompted the electron to emit photons with exactly the same energy and momentum.
For each photon that makes the atom itch, there are now two emitted photons.
Einstein wrote to his friend Michelle beshoin 1916: "I suddenly realized the absorption and mission of radiation . ".
Over the next two decades, several physicists have proposed the use of excitation to produce high emissions.
Intensity, coherent radiation beam.
Every photon that is emitted will cause other people to itch.
The excitation electrons produce a large number of photons of the same wavelength, which travel in the same direction, like a step-by-step camp.
But no one knows how to put this theory into practice.
Stimulus launch was not used for the development of maser until 1950 seconds-
Microwave effect of laser.
The emergence of microwave radiation and its interaction with molecules have been greatly promoted by the military.
During World War II, physicists developed radar that used ordinary radio waves to detect enemy planes.
Because for ease of use, the radar is pushed to shorter and shorter wavelengths, and when the war is over, the military has redundant complex microwave devices, which scientists are happy to accept.
One of the scientists, Charles Towns' young physicist, joined Columbia University and was fascinated by the way molecules absorb and emit energy.
At that time, considering many scientific achievements during the war, the military was investing money in physics research, with relatively few strings attached.
"Military funding is not as targeted as it is now," Tang recalled . ".
Tonis was fascinated by Short's research.
Microwaves are called millimeter wave because they interact with atoms and molecules more strongly than microwaves with longer wavelengths.
He believes that if this radiation can be produced at high intensity, a better probe of atoms and molecular structure will be produced.
But no one knows how to produce a stable, strong millimeter wave source.
The pressure is increasing as towns is appointed chairman of the Navy millimeter-level committee
Wave studies and reports of no progress.
Breakthroughs were made in April 26, 1951.
The Navy committee meets in Washington, D. C. C.
Thomas is a father with children. He is used to getting up early.
Be careful not to disturb his room.
Partners, collaborators and future brothers at Franklin Park Hotelin-
Lao asselo, towns climbed out of the room and sat on a bench in the park next to him.
Tunis recalls that the red and white cuckoo is in full bloom, but his focus is on the millimeter-wave puzzle.
When he was familiar with Einstein's theory of radiation, Donis knew the source of photons ---
Microwave included-
It is possible to stimulate atoms or tools ecules to glow at exactly the same frequency, thus increasing the intensity of the output signal.
But there are many stumbling blocks.
He needs to find a way to keep more electrons at lower energy levels and higher energy levels. [
Slightly] Illustrations
A group of atoms in a state of thermal equilibrium (
Reached the surrounding temperature)
Atoms that do not excite electrons are often more than atoms that stimulate electrons.
As a result, any temporary enhancement from the signals that stimulate the emission will soon be absorbed by the electrons at the lowest energy level.
In a microwave signal, it is not a net gain but a net loss.
"I can't completely restructure the order of thinking that drives me through this puzzle, but the key revelation comes from Aroush," Thomas wrote in his 1999 memoir . ".
The second law of thermodynamics assumes the equilibrium of thermodynamics;
But this is not a must!
A little bit of a natural twist.
"If a device can be made to keep the set of atoms or molecules unbalanced ---
More of them are in higher energy states compared to lower energy states-
Then, Einstein's excitation can really enlarge the input signal.
The idea of the town is too immature to be discussed at the Navi committee meeting.
But soon after returning to Colombia, he went all out to pursue the dream.
He focused on ammonia gas molecules made with tritium, a heavy isotope of hydrogen.
The strategy of the city is double.
First, using a changing electric field, he will separate ammonia molecules with higher energy from ammonia molecules with lower energy.
And then he will trap his superiors.
Energy molecules in the cavity, designed to keep the microwave radiation they emit bounce back and forth through the gas.
This radiation stimulates more electron-emitting microwaves and produces an increasing amplification of the original microwave signal.
Thomas recruited two young researchers, Herb Zeger and Jim Gordon, to develop the device at Columbia University.
The work took three years and everyone in the department of physics at Columbia University was patient.
One day, one of the university's Nobel Prize winners in physics, I. I.
Rabbi, dean of the department, Polykarp Gushi (
Became a Nobel Prize winner two years later)
Visited the town.
They told him not to waste any more time.
Downes listened, but ignored the advice of the two heavyweights.
"Fortunately, I have a term," he said.
In addition, he and his students have reason to remain optimistic: although they have received signs of a stimulus launch.
At the beginning of April 1954, Gordon attended a seminar held by Thomas and announced that the amplification had been achieved.
Gordon and Downs developed the first equipment to show "Microwave Amplification of excitation radiation of radiation ---the maser (SNL: 2/5/55, p. 83).
What Thomas does not know is that several other researchers are also considering similar ideas about maize.
At Marylandin College Park University, Joe Weber published a short article proposing to use the launch as a radiation amplifier.
On 1954, AleksandrProkhorov and Nikolai Basov of the Lebedev Institute of Physics in Moscow wrote an article about the generation of a microwave oscillator with a bunch of alkali halogen molecules.
When most other researchers marvel at the concentrated beam produced by maser and work to improve its design, towns span to shorter wavelengths ---
Infrared and Visible-
The light part of the spectrum.
"I want to develop an infrared [
Version of Masawa]
Because I saw a new way to detect atoms and molecules at an infrared wavelength . "
He said: "When I sat down trying to understand how we were able to get to these wavelengths, write the equations and check my notes, I realized, 'Hey, it looks like we can even go straight to the short-wave length-light waves.
Due to the short wavelength, a new design challenge is presented by an optical version of maserposed.
Some physicists even claim that this is impossible, based on their understanding of quantum theory.
But, as Thomas pointed out, scientists are familiar with the interaction between light and Atoms at infrared and visible wavelengths.
Together with Gordon Gould in Colombia, Townes discusses a visible experimental arrangement
The light version of maser.
A mirror system will pass the light source back and forth through a carefully selected material to stimulate the excited atom and amplify the radiation, not the microwave cavity of the laser.
Gould realized that he created this design for the term laser (
Light Amplification by radiation excitation Emission)
, Can produce a high-intensity beam of intense focus, carrying more energy than the beam produced by the Pulse Ze.
Gould was keenly aware of the potential application, and his notes were notarized at a local candy store on 1957.
Later, these notes will be part of the a30.
In the patent war of the year, Gould finally won the approval of hisideas.
Meanwhile, Thomas and his colleague Schawlow work at the movedto Bell Lab in Murray Hill, New York. J.
, Detailed their own concepts and designs in the landmark 1958 paper called "infrared and optical masks (SNL: 2/7/59, p. 83).
After reading this paper, several teams joined Thomas and Schawlowin to become the first team to build the device.
Each group wants to use a different material or atomic source to amplify the visible light.
Physical science historian Spencer Petter points out: "You rarely come across situations where there is a starting gun and everyone is crying at the same time," he is affiliated with the American Institute of Physics.
At Bell Labs, Schawlow studied a solid material as a laser medium, while his colleague Ali Javan, William R. Bennett Jr.
And DonaldHerriott to review the gas body.
Gould left Colombia to join a private research firm, TRG, who submitted a proposal to the military to use metal vapor in lasers. [
Slightly] Illustrations
On September 1959, at the quantum electronic conference held in the Catskill Mountains in New York, it was clear that other teams, including Mayman and Soviet researcher Basov ambrohov, also joined
At that meeting, Schawlow reported his analysis that pinkruby would not be a good laser medium for visible light.
Schawlow's statement is one of the reasons why Maiman succeeded in the 1960 incident, which surprised many people (SNL: 6/23/60, p. 53).
Some scientists, many of whom had barely heard of Mayman, refused to believe in California at first-
Researchers based on the east coast of the United States have dug all the people out, and they have received most of the money and equipment to make lasers.
"It's like a horse running from outside," Weart said . ".
"They didn't even know he was in the game.
"From the very beginning, Maiman has adopted a different strategy than that of a competitor, aiming to develop a pulse laser, rather than a device that emits a stable amplified beam, which allows him to use more basic equipment.
His equipment is small and simple.
Appearance: a kind of Luo-shaped ruby with a silver end and sitting in a coiled flashlight reflecting light.
When the light flashes at the right energy, its photon stimulates the chromium ion in the Ruby to emit the same visible-light photons.
These photons are reflected back into Ruby, which in turn stimulates the production of more identical photons until half of the luminous flow of clones that have never been realized in the lab burst out
Silver mirror at one end of the device.
Physicists know that lasers are more than just visible.
Journey to the light of maize
It can detect and manipulate sub-atomic structures smaller than microwave devices (SNL: 1/20/62, p. 42).
Maiman, the winner and loser, released his findings, with very bad luck.
While he quickly submitted an article to the physics review letter, the editor Samuel goodsmit also quickly rejected the article
Theoretical physicist, he mistakenly believes that Myman's device is just an unimportant variant of maser. A scant, four-
In August 1960, the chapter description of Myman's work appeared in Nature.
Hughes Company, July
At a news conference in New York, Mayman's invention was promoted, but the public relations scientist said Mayman's laser did not look real enough.
He convinced Mayman to pose with a larger flashlight and Ruby Roda than he actually used.
Many researchers, without publishing their papers for analysis, rely on the misleading promotional photo that is still being distributed today to replicate Mayman's findings.
By the end of the summer, researchers at Bell Labs did succeed in making their own ruby lasers.
Public relations personnel were once again involved in the operation, convincing scientists to ship their equipment, much larger than Mayman's, to reach an old radar tower at Bell's main headquarters in Murray Hill, send a laser pulse to another bell building on Crawford Hill, New York. J.
About 40 kilometers away. SNL: 10/15/60, p. 245).
The publicity stunt attracted some media, and many reporters did not seem to realize that the bell device was not the first laser.
Goudsmit did agree that the bell research paper on Ruby laser published in the Physical Review letter did not give Maiman credit for building the first laser, which may not help.
Another team of Bell scientists, including Javan, Bennett and Herriott, did achieve a new milestone in December 1960, successfully creating the first gasbased laser (
This produces a stable, not a pulse beam)
Use helium and neon lights as laser materials.
More complex stable versions over the years
Beam lasers will change electronic communication and many other technologies.
Eventually, the first Nobel Prize in Laser Physics was awarded in 1964 for its theoretical and experimental work in developing the device. SNL: 11/7/64, p. 295).
Schawlow shared his contribution to the laser spectrum and won the 1981 Nobel Prize in Physics (SN: 10/24/81, p. 261).
In general, the Nobel Prize has been awarded to more than a dozen laser researchers. Related research.
Although he has been selected to the National Inventor Hall of Fame and won several international awards, he has never won a Nobel Prize.
Gould was also handed over to aNobel, but his case eventually earned him millions of royalties.
"I think it's possible that everyone except the town residents thinks they don't get a fair share of credit," said Weart . ".
"It's like a legacy;
Everyone thinks they should get a little bigger share, but only 100%.
"Looking back, it is clear that the world has benefited from the laser --
Although not as the public initially imagined.
At a press conference on July 1960, some journalists who reported the invention of Mayman hyped that the laser was a death.
As the lasers get stronger and stronger, researchers will jokingly call them "one-
Gillette or 8-
Gillette "devices, depending on how many blades a beam of light can pierce.
In 1964, a laser appeared in James Bond's blockbuster golden finger, which passed through a metal table and threatened to cross bond.
Regardless of the potential for destruction of the initial propaganda, the laser has made significant progress in the medical, communications and industrial fields.
Biologists and physicists continue to use lasers in the pursuit of basic science.
Given Einstein's role in developing the basis of laser theory, one of its applications may be just ultra-pure lunar laser ranging to test another Einstein's theory ---
General relativity
If gravity is weaker than he calculates, it may appear as the Earth changes --moon distance.
Historian Weart says it may also be appropriate to acknowledge another important role on the 50 th birthday of another scientific father who commemorates Einstein and laser ---light itself.
"We should attribute this amazing phenomenon to the light," he said . ".
It is the properties of photons that enable the laser to use these wavelengths in such a wonderful way.
"The modern version of the ruby laser, first built by Theodore Maman, relies on two phenomena: excitation Emission and amplification of photons.
Other lasers rely on the same principle.
In addition to a ruby laser that exchanges laser materials, scientists can also make lasers that emit different wavelengths of radiation.
Here are some examples. Solid-
The first ruby laser is an example. state laser.
In this case, the ruby crystal emits red light at a wavelength of 694 nm. Solid-
Today's national lasers are usually made of glass or crystals that are doped with rare earth elements.
A laser made of nd
The doped yttrium aluminum garnet stone crystal can emit infrared rays with a wavelength of 1,064 nm. [Graphics omitted]
Semiconductor lasers: in these lasers, the small chip of the semiconductor replaces the Ruby stick.
Two external semiconductor layers are reallocated by the middle layer, which produces radiation when the reverse charged particles meet in the middle layer.
These devices are usually used as laser materials in the near
Infrared and red regions of the EM spectrum.
They are small in size and low in power consumption and are ideal for data transmission and spectrum technology.
These lasers are also available in CD players and laser indicators.
Dye laser: the use of organic dyes, usually in liquid solutions, the photobomb is usually from UV to nearinfrared.
Ruidamin 6g is a dye that is widely used because it is the most efficient dyeing material.
While most of the original work that produces short laser pulses depends on these lasers, they are mainly used for spectra today.
Gas laser: relies on the current generated by gas discharge to produce light, and various versions of this laser type can work in completely different radiation states. Helium-
For example, a neon laser produces 632 of the light. 8 nanometers--
But the green light can also be given.
The first pulse (
Microwave version of laser)
The ammonia gas used produces radiation at a wavelength near 1. 25 centimeters. Carbondioxide-
Radiation generated based on laser is about 10.
6 microns, at the same time-
Ion lasers can produce light with a wavelength of 351 nanometers.
A combination of inert gas and a reactivated substance as a laser medium to produce ultraviolet rays, usually between 351 and Nano, for fine surgery. Free-
Electronic laser: Here, the laser medium is an electron that is accelerated to near light. speed.
The beam passes through the undulating magnetic field, causing photons to be emitted in a unique way.
This laser has the strongest power and the widest frequency range;
Different types can produce radiation across the distance.
Infrared, visible, UV and X-ray ranges.
The wavelength dropped to 6.
5 nanometers have been achieved.
These devices can be used for isotope separation, plasma heating, and particle acceleration.
Unfortunately, their settings are big and expensive.
The long road to the laser [
Slightly] Illustrations
1917 Albert Einstein published a prediction that electrons caused by photons would drop to a lower energy level and release additional radiation, later known as "se" in the laser ".
1924 Richard Tolman suggests that the excitation Emission can produce radiation, thereby enhancing the radiation, suggesting that "radiation light amplification" in the laser ".
1928 Rudolf lunderberg and Hans copfeynman presented the task of stimulation.
1951 Charles Townes describes how ammonia gas emits radio waves, which are called maser (
Microwave version of laser).
1954 Nikolai Basov and Aleksandr Prokhorov presented a working maser to towns and colleagues, respectively.
1956 Robert Dicke filed a patent that claimed to describe how infrared lasers were manufactured, but the patent was rarely made public.
1958 Townes and Arthur Schawlow published a paper describing the principle of optical pulse (
Laser now).
1959 Gordon Gould, who created the word "laser" a year ago, filed a patent application.
1960 Theodore Maiman developed the first working laser, rubylaser, at Hughes Research Laboratory. [
Slightly] Illustrations
1960 all Javan demonstrated the continuous operation of helium-neongas laser. (
A similar beam between the Prism and the two mirrors is shown above. )1961 Columbia-
The Presbyterian Hospital used a ruby laser on a person for the first time, destroying the retinal tumor.
1963 Zhores ALferov and Herbert Kroemer independently propose semiconductor lasers for fiber optic, CD players and laser indicators.
1964 Thomas, Basov and Prokhorov (shown)
Won the Nobel Prize that led to Masawa and laser. [
Slightly] Illustrations
1965 James Russell invented the CD, although it didn't become popular until it was made on a large scale in the 1980 s.
1966 Charles Kao and George Hockham show that the fiberglass can transmit laser signals effectively if the glass is pure.
1970 The upcoming glass work makes it low
Fiber loss.
1970 Arthur Ashkin describes the use of laser manipulation of particles, laying the foundation for optical Twitter.
1971 Xerox has developed its first laser printer.
Wrigley 1974 A 10-
Chewing gum is the first item purchased through a laser-scanned UPC barcode.
1976 John Madey and colleagues at Stanford University showed
Electronic laser through near light
Make electrons generate photon flow through a magnetic field.
1977 Universal telephone and electronic devices send the first real-time phone traffic over fiber in Long Beach, California.
1981 Schawlow and nicollaas Bloembergen have contributed half of the Nobel prizes for the development of the laser spectrum. [
Slightly] Illustrations
1982 the first music CD is a "visitor" made by ABBA "(cover shown).
1983 President Reagan calls for laser
Based on the defense system in his Star Wars speech.
1985 Zhu steven Wen led the first work to cool and capture atoms with a laser. [
Slightly] Illustrations
A 1987 laser was first used for corrective eye surgery.
1988 first transatlantic fiber
The cable is down. [
Slightly] Illustrations
The 1995 Kuiper Airborne Observatory detects the first natural laser in space. (
A modified military cargo aircraft with a reflection telescope was presented. )
1996 the laser power produced by Lawrence Livermore National Laboratory exceeds 1 Watt, exceeding the entire power
Power generation capacity in the United States.
1997 researchers at the Massachusetts Institute of Technology made the first atomic laser.
The device produces a bunch of atoms.
1997 Chu, Claude Cohen
Tannoudji and William Phillips share the method of cooling and capturing atoms with a laser.
2000 Alferov and Kroemer shared half of the Nobel Prize for their contributionspeed-and opto-electronics. 2000 John L.
Hall and Theodor Hansch have developed optical frequency comb technology in which ultra-short optical pulses produce frequency peaks that can be used as a ruler. 2001 A long-
For the first time, a distance laser communication link was established between the Earth.
Satellite Orbit (
As shown in the figure).
2004 laser-
The electric computer mouse is introduced.
2005 Hall and Hansch shared half of the Nobel Prizes for their contribution to the spectrum. [
Slightly] Illustrations
2009 Kao won the Nobel Prize for his progress in visual communication.
2009 the National Ignition Facility produces laser shooting with energy exceeding 1 million joules (
Target Chamber shown).
Lasers, once called "solutions to finding problems", have now penetrated into many areas of life. [
Slightly] Illustrations[1]
Communication: laser diodes send optical pulses through fiber bundlesoptic cables (shown).
Lighter, stronger, faster and more efficient compared to global cable, fiber-optic transmission telephone, Internet and cable TV data.
Lasers are also used for communication between satellites in space.
Back to Earth, the laser writes and reads digital information on cd and dvd. [
Slightly] Illustrations[2]
Security: like in a spy movie.
Scan through the laser beam and blow the whistle of the intruder
Although in real life, the beam is invisible.
Laser can also verify the authenticity of documents such as ID card and passport, and improve the security of communication by coding eavesdropping
Resistance information in a single photon. [
Slightly] Illustrations[3]
Entertainment: lasers are used for special effects in movies, impress the audience at concerts and act as their own main event in laser lighting performances.
Laser tag gaming sites have also appeared across the country. [
Slightly] Illustrations[4]
Military: an indicator of the laser used for the probe and bomb.
Laser can confuse heat
Seeking weapons and being developed to destroy ballistic missiles (U. S.
The Air Force airborne laser showed that a missile like this was shot down). [
Slightly] Illustrations[5]
Medicine: lasers can correct vision by reshaping eyeballs, surgical incision, burning wounds, and treating cancer (shown)
And a clear image of the body.
As costs go down, lasers are as common in hospitals as blue scrubs. [
Slightly] Illustrations[6]
Measurement: by reflecting the laser from a distant object and timing the time the light returns, the lidar (
For light detection and ranging)
Distance can be measured very accurately (
Lower Manhattan in September 2001).
The technology draws an ice flow chart, monitoring on the beach, measurement of chemicals in the atmosphere, and speeding cars.
It also detects snow in the Martian atmosphere. [
Slightly] Illustrations[7]
Business: thank them for their high-
From paper to fabric, the laser can cut everything clearly (shown)--
Weld the pieces together.
The laser is also used to mark these pieces with ID numbers.
After the final product arrives at the store, bar codes, laser reading, marking items to track inventory and check out easily. [
Slightly] Illustrations[8]
Basic discovery: Laser also brings new tools for basic research.
Laser can help take clear photos of the space by eliminating air pollution (
Shows the laser from the optical range of the New Mexico spark)
Can accommodate and manipulate micro objects (
Including live bacteria)
The atom can be cooled to almost absolute zero.
Explore more * for information on the one-year laser celebration visitwww. laserfest. org * C. H. Townes. How the laser-happened.
Oxford University Press, 1999
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