Laser Beam

The word 'laser' is an abbreviated form of the term, Light Amplification by Stimulated Emission of Radiation. Laser beam is actually an electromagnetic radiation emitted from a device called laser. The main characteristic of a laser is emitting light with high temporal and spatial coherence. The process of optical amplification lies at the core of production of laser beam. The photons produced by stimulation are emitted in the form of laser beam.
Facts about Laser Beam
The light produced by laser is in the form of a narrow beam. It can be concentrated on tiny spots. Irradiance of a high degree can therefore, be achieved; the concept of irradiance is described as the power of electromagnetic radiation per unit area at a given surface. Another way in which the laser beam is launched/directed is that in which low divergence is achieved. It allows the power to concentrate even at a longer distance from the source of light.
History of Laser
Theodore Maiman is credited with the demonstration of working of laser for the first time in 1960. He gave the demonstration of laser's working at the Hughes Research Laboratories. Albert Einstein talked about the subject of laser in one of his papers in 1917. Einstein also spoke about Rudolph W. Landenburg in this paper. Landenburg was the person who had supported/confirmed the existence of emissions produced by stimulation in 1928. Valentin A. Fabrikant in 1939 made a prediction about use of such kind of stimulated in reality. The serious study of laser technology had started in the year 1957 and it was carried out by Arthur Leonard Schawlow and Charles Hard Townes. The use of laser technology in barcode applications for departmental stores supermarkets began in the year 1974.
Applications of Laser Beam
The laser beam is used in many different fields. It is commonly used in the operation of CDs and DVDs. Computer mice, optical scanners,laser pointers and printers are other devices in which laser beam finds application. It is also used in the production of holograms. The survey of land required in building construction is carried out by means of laser beams. In the medical field surgeries and cosmetic procedures are conducted with the help of laser beams. Get more information on laser eye surgery. A microwave amplifier that worked on the principles of laser was produced by Herbert J.Zeiger and James P.Gordon in 1953.
Laser Beam Welding
It is a technique used to weld/join together metal pieces by means of laser beam. The benefit of using laser beam for welding is that the source of heat can be concentrated in a narrow space; it allows for deep welds. The success rate of welding too is high. The laser beam welding process mostly finds applications in the automotive industry. The gas-state and solid-state are two types of lasers used in welding. In the solid-state lasers chromium, synthetic ruby and aluminum oxide are the media being used. A mixture of nitrogen, helium and carbon dioxide is used in the gas lasers. The purpose of both gas-state and solid state lasers is however, the same i.e. production of stimulated photons.
Laser Beam Divergence
The rate at which a laser beam expands from the beam waist is referred to as its divergence. A beam with a low divergence is considered better from the point of operation of these devices. The different techniques such as scanning pinholes, variable apertures, CCD relays and knife edges are used in the measurement of laser beam divergence. The beam profiler makes it easy to measure the divergence.
The laser beam is an important invention and has great scope for technological development. Improvements in the fields like medicine, entertainment, defense, computing, telecommunications, etc. can be brought about by means of laser beam technology. Even today, we can find many applications of this technology including that of laser cutting and many others.
The article deals with information about the topic of laser beam in short. It helps understand the properties of this beam and the applications/uses. The laser beam is an important invention as it helps in carrying complicated tasks including surgeries, welding narrows points, etc.

How do black holes affect things near them?

Are we  in danger of being gobbled up by a  black  hole?  Actually, no.  We’re pretty safe.The  gravity  from  a black  hole  is  only dangerous  when you’re  very  close  to it.  Surprisingly,  from a  large  distance, black hole gravity  is no different  than  the gravity  from a star with the same mass. The strength of gravity depends on  the mass of the object and your distance from it. If the Sun were to become a black hole (don’t worry, it’s way too lightweight to ever do that), it would have to shrink so much that its event horizon would be only 6  km  (4 miles) across. From  the Earth’s distance of 150 million km (93 million miles), we’d feel exactly the same gravity as we did when the Sun was a normal star. That’s because the mass didn’t change, and neither did our distance from it. But if we got up close to the black hole, only a few kilometers away, we’d definitely feel the difference! So stellar-mass black holes don’t go around tearing up stars and eating everything  in sight. Stars, gas, planets, and anything else would have  to get up  close and personal  to a black hole  to get trapped. But space  is big. The odds of  that happening are pretty small. Things  are  different  near  a  supermassive  black  hole in the center of a galaxy. Every few hundred thousand years, a star wanders  too close  to  the black hole and gets torn apart. This produces a blast of X-rays that can be visible for decades! Events like this have been seen in other galaxies, and they are a prime target for satellites such as EXIST to reveal otherwise “dormant” black holes.Astronomers have  found another amazing  thing about galaxies:  the stars  in  the  inner parts of a galaxy orbit the  galactic  center  faster  when  the  galaxy’s  central supermassive black hole is more massive. Since those stars’ velocities are due to the mass in the inner part of the galaxy – and even a monster black hole is only a tiny fraction of  that mass – astronomers conclude  that  the total mass of the inner region of a galaxy is proportional to  the  (relatively  very  small) mass of  its  central black hole! It’s as if the formation of that black hole somehow affected  the  formation  of  the  billions  of  normal  stars around  it. EXIST will probe  this suspected  “feedback” between  galaxy  formation  and supermassive  black  holes by  investigating  black holes  in  a  very  large sample of galaxies.

How do black holes form?

The  most  common  way  for  a  black  hole  to  form  is probably in a supernova, an exploding star. When a star with about 25 times the mass of the Sun ends its life, it explodes. The  outer  part  of  the  star  screams  outward at  high  speed,  but  the  inner  part  of  the  star,  its  core, collapses down. If there is enough mass, the gravity of the collapsing core will compress it so much that it can become a black hole. When it’s all over, the black hole will have a few times the mass of the Sun. This is called a  “stellar-mass  black  hole”,  what  many  astronomers think of as a “regular” black hole. But there are also monsters, called supermassive black holes.  These  lurk  in  the  centers  of  galaxies,  and  are huge:  they can be millions or even billions of  times  the mass  of  the  Sun!  They  probably  formed  at  the  same time  as  their  pa rent  galaxies,  but  exactly  how  is  not known for sure. Perhaps each one started as a single huge star which exploded  to  create  a black  hole,  and  then accumulated  more material  (including other  black  holes).  Astronomers  think there is a  supermassive black hole in the center of  nearly  every  large galaxy, including our own Milky Way. Stellar-mass black holes also form when two orbiting neutron  stars – ultra-dense  stellar  cores  left over  from one kind of supernova –   merge  to produce a short gamma ray burst, a tremendous blast of energy detectable across the entire observable Universe. Gamma-ray bursts are in a sense the birth cries of black holes.

Real Ghostbusters

Respected physicists are turning their scientific minds to measuring the paranormal and other bizarre phenomena. Read on to see what they’ve discovered so far.

 

 

How to win a coin toss

In an experiment using a random event generator (REG), scientists from Princeton university in the US put the ‘mind over matter’ theory to the test.

The REG works similarly to flipping a coin so that if left alone it should flip as many heads as tails. However, scientists found that volunteers were able to sway the results seemingly by the power of their mind.

In fact, people as far away as Hungary and Brazil were able to influence the results of the REG. They’ve yet to find out why this happened but stronger emotions seemed to increase the effect. So next time you flip a coin you know what to do…

 

 

 

Chicks have powers too

A test involving a robot known as the Tychoscope and a group of chicks found some very interesting results.

The Tychoscope is a little robot programmed to randomly wander around a room. But when a cage of chicks was brought into the room, scientists found the robot’s behavior changed dramatically.

Rather than randomly maneuvering around the room, the robot spent more time with the chicks. Scientists suspect the chicks may have willed the robot to stay close.

For some of the chicks, the robot was the first thing they saw after they hatched so may have developed a parental bond with the robot.

 

• The ones who had already read the book “The Holographic Universe” by Michael Talbot, surely think these experiments can be true.
  
 

Weird (scientific) mistakes!

The Earth is not flat, and the sun doesn’t go round it. Scientific history has been wrong on many occasions. But which of these common misconceptions do you hold?

 

The daddy long legs is one of the most poisonous spiders in the world but its fangs are too small to inject the poison into you

This is false. The daddy long legs, or ‘harvestman’ spider does not even have venom glands, let alone fangs with which to bite you. They are completely harmless to humans. Flies, however…

  The only man-made object you can see from the moon is the Great Wall of China

This rumour began around the time of the first Apollo mission, but unfortunately it is untrue. The Great Wall of China, although long, is only around 10 ft wide. If you could see the Great Wall from space, you’d also be able to see the M25!

Lemmings throw themselves off cliffs

Nope. The Disney film ‘White Wilderness’ started this myth around 60 years ago, but it is untrue. The lemmings in the film were pushed off the cliff by the production crew, who were attempting to show the colony migrating.

The ‘theory’ of evolution is not a fact

An extremely common misconception. Although ‘theory’ may mean ‘educated guess’ in everyday language, in scientific terms it means something which has been rigorously tested and confirmed by experiments to be true. Evolution is a scientific theory just like gravity, or relativity – it’s not just Darwin’s opinion on how humankind came about.

Hair and fingernails keep growing for two days after you die

This gruesome idea is far too weird to be true. In fact, your skin contracts slightly after you die, exposing more of your hair and fingernails at the roots.

 

There is no gravity in space

Everywhere in the universe has gravity, no matter how far away from a planet or star. Astronauts appear to be floating, but are actually falling – they are pulled by gravity because they are in orbit around a planet.

Your shout!

Did you believe any of these were true? Share your thoughts by posting a comment using the link below.

Can we ever go back in time?

Time machines are commonly seen in science fiction movies and books, but no one knows how to build one.

However, it is possible to slow down time by travelling very fast relative to someone who is stationary. This was predicted by Einstein’s theory of relativity at the beginning of the 20th centaury and has since been proved many times.

One of the best examples of this was demonstrated by putting a very accurate clock on board a passenger jet. Another identical clock was kept on the ground and synchronized with the clock on the plane. After a number of long distance flights the two clocks were compared and the one that had been on the plane was running behind the clock that had stayed on the ground. The difference between the two clocks was exactly the difference predicted by the theory of relativity.

It is important to understand that this slowing down of time depends on the speed you are travelling at relative to someone else. None of the passengers on the plane would have noticed anything strange - as far as they are concerned time is passing as usual. It is only when they get off the plane and compare their watches with someone who has been stationary relative to them that they notice a difference.

Passenger jets fly at about 600 miles per hour which seems pretty fast. However, after the experiment described above the difference in time between the two clocks was less than a billionth of a second, which is why very accurate clocks were needed.

If you could travel at speeds close to the speed of light (about 186,000 miles a second) time would slow down significantly, from the perspective of someone who is not moving. Unfortunately we do not know how to build rockets that fast!

See the world differently by Physics

Seeing Inside

Once upon a time, not so long ago, our eyes were our only way of seeing the world. But increasingly sophisticated instruments developed by physicists have opened a window onto sights that our ancestors would never have dreamt of.

Microscopes have exposed the inner workings of our cells, making modern medicine possible. The latest electron microscopes can even zoom in to the level of individual molecules and atoms, whilst revolutionary imaging techniques such as MRI scanners or X-ray machines allow doctors to spy on brain activity or broken bones.

Meanwhile, progressively more powerful telescopes mean that we can explore our universe from the comfort of home. Space telescopes like Hubble have sent back thousands of stunning glimpses of far flung stars, planets, galaxies and nebulae.

You may not need to look further than the end of your nose to see a physics instrument at work. If, like over half the population, you wear glasses or contact lenses, you can thank physicists’ understanding of optics for bringing your world into focus.

More than this, physics gives us a deeper understanding of invisible processes, such as the way gravity works or how bats use ultrasound, enabling us to see our world like never before.

 

Revealing The Invisible

Space shields may sound like they belong on Star Trek, but there's one protecting you right now: the Earth’s magnetic field.

Our planet is under continual assault from the Sun, which sends streams of electrically charged particles hurtling through space at speeds of up to 750 km/sec. Known as the solar wind, these particles can ionize atoms and harm cells, potentially inflicting some serious damage. But don’t panic! Most of these particles are deflected by the Earth's magnetic field before they even reach our atmosphere, which itself mops up most of the stragglers.

The Earth produces a vast magnetic field stretching out into space, just like the field that would result from a gigantic bar magnet placed in the planet's centre. Buffeted by solar wind, this magnetic field is distorted into a tear-drop shape and is called the magnetosphere.

Magnetic fields are of course invisible, but physicists are able to build up a picture of the magnetosphere and monitor its natural variations over time using specialized instruments on board satellites.

They are also on the lookout for clues suggesting that the Earth's poles might soon flip – a phenomenon which has occurred regularly throughout the planet's history.

We'd be lost without the magnetosphere in more than one sense: not only would adventurers' compass needles no longer point North, but we, along with the rest of life on Earth, would be unlikely to survive. Even with the magnetosphere's protection, periods of exceptionally high solar activity have been known to disrupt power grids, satellites and GPS navigation.

 

A New Point Of View

Ever wondered if you might one day visit the Moon? Russian astronaut Yuri Gagarin became the first man to venture into space in April 1961. Just eight years later, Neil Armstrong set foot on the Moon's surface. It took about four days for his Apollo 11 spaceship to make the 360,000 km trip.

Both these men – along with all other space travelers - were bowled over by the breathtaking view they got of the Earth. One of the most striking images ever captured on film was this photograph, taken during the Apollo 8 mission in 1968 as the crew watched the Earth rise over the Moon's surface – in the same way that we might watch a sunrise. Back on Earth, people caught an unprecedented glimpse of the planet we call home from an outsider’s perspective: a small blue marble lost in space. They were truly seeing the world differently.

Today’s space scientists have set their sights on Mars, with space agencies ESA and NASA both hoping to send a manned mission to the red planet in the next 30 years. The latest technology has also allowed us to scour the far reaches of our galaxy for planets that could harbor life. Finding out one day that we are not alone in the universe may once again revolutionize the way we think.