On 21 July 1969, before leaving to Earth, astronauts Neil Armstrong and Edwin Aldrin had set up an array of small reflectors on the surface of Moon. About ten days later, a team of astrophysicists at University of California’s Lick Observatory, pointed their telescope towards the precise location of human landing and sent a small pulse of power into the tiny instrument they had added to the telescope. The narrow beam of red light that emerged from it pierced the sky and disappeared into outer space. Slightly more than a second after the beam hit the reflectors, the Lick team detected the faint reflection of it. The time period between the launch of the pulse of light and return of it permitted calculation of the distance between Earth and Moon with unprecedented precision, to the extent of correction within an inch. The wonder ray that made this possible was LASER, a brand new invention that was demonstrated just nine years before, in 1960.

It was the brain child of a 32 year old engineer-turned-physicist at Hughes Research Laboratories, Mailbu, California. His name was Theodore Maiman, but at that time, it was considered rather useless, upon which even his colleagues moked him, saying. “Aha! Great solution! But what could be the problem?” Infact nobody could not even imagine that Maiman’s invention would become literally the workhorse of modern physics and so engraved on to everyday life. And today in its fiftieth birth anniversary, LASER is here to cool atoms, send data mend eyes and trigger fusion. While it is the “death ray” in military applications, it is forming part of high-life through spectacular “LASER shows” in stage concerts. It is there in our DVD’s, Bar-code scanners and latest mobilephones and so simply, it is unavoidable.

The History of LASER
It goes to Einstein for a starting point in the history of LASER, who at the prime of his fame, establishing the idea of stimulated emission, in 1917. It was a re-derivation of Max Plank’s Law of Radiation through conceptual advancement. However, till the end of 1940s, the principle of stimulated emission was hardly sought, as the concept was largely considered a theoretical one. Einstein based it in thermodynamics, that if light can force an atom to go upto high energy states, it can also force an atom to give up its energy and drop to lower states. While this “stimulated energy loss” happens, it will also lead to amplification of the emitted photon, a phenomenon called Coherent Amplification. In short, it is amplification stimulated by light” creating a stronger emission (later abridged as LASER – Light Amplified by Stimulated Emission of Radiation). The first brilliant success was made by Charles Towens, who used this phenomenon to amplify the microwaves. The resultant device was called MASER, the acronym for ‘Microwave Amplification by Stimulated Emission of Radiation’. And in their historical paper published in Physical Review, Townes and his co-worker Arthur Schawlow hoped that the MASER concept could be extended to an “optical MASER”, in other words, the LASER.

Thus it paved the way for a race to build a LASER, in which Bell Laboratories was destined to win as the research group led by Charles Townes was there. Bell Lab, the then called Bell Telephone Laboratories, was a well funded research institute with a backdrop of several high profile achievements. Even within Bell Lab there were other groups, well outside it also, to join the race. In US alone, there were more that six research labs including the much famous General Electric and IBM. Townes former PhD student was also among the rivals, Gordon Gould, who abandoned his thesis work and joined a private company engaged in LASER research, to realize it. But, the dark horse was yet to join the race, Theodore Maiman, who was then at Hughes Research Laboratories, the research arm of Hughes Aircraft Company. Maiman’s engineering and physics experience was an added advantage, when the company wanted a MASER, as per the contract it signed with the US Army corps of Engineers. It was his efforts to make the MASER more compact and practical, that led to the LASER.

Maiman’s “Eureka”
The reason why light is usually absorbed in materials IS simply that substances almost always have more atoms or molecules in lower states than in higher states so that more photons are absorbed than emitted. So, the trick in making a LASER is to produce a material in which the energies of the molecules or atoms are put in excited states than in ground states. A wave of electromagnetic energy moving through such a substance will pick up, rather than losing energy. However, just one pass of the wave through the substance wont give much amplification and so multiple reflections are to be there. This is achieved by placing two parallel mirrors on either side of the material, of which one mirror is partially transparent. When the internal reflections are enough to build up substantial amount of power, the ray will penetrate out through the transparent mirror. This was the theoretical blue-print and next came the choke of the material. Maiman was familiar with the properties of Ruby from his earlier works and so he selected it. Ruby is a crystal of Aluminum Oxide (Al2O3) in which a few Chromium atoms are dispersed as impurities. These Chromium atoms which exist as ions by losing three of its electrons can absorb green light from the visible spectrum and go to excited states. When electron fall back to ground state from these high energy levels, they fluoresce in red. Maimum was thinking that he could use this red fluorescence to create LASER.

The path ahead was however not smooth as he thought. The first blow came from Arthur Schawlow who was his brother-in-law and work-mate. In September 1959, shortly after Maiman started his project, Schawlow publicly declared that Ruby couldn’t be a candidate for stimulated emission. He argued that, for that to happen, more electrons need to reside in the upper energy level than in the lower ones, a condition known as ‘Population Inversion” As per Schawlow, it was impossible to achieve this, for a three-level energy system such as Ruby, while it is much easier for a “four-level energy system”. Whether this was practically true or else was not the question but with repeated counseling against Ruby that came all along from respected scientists, Maiman’s employer stoped funding his research. For Maiman it was not a discouragement as he was willing to spend from his own pocket, but the next hurdle was not much beyond. The problem was the ‘quantum efficiency’ of Ruby, ie, the number of fluorescence-photons emitted for each light photon absorbed. In a much discussed paper published in the Review of Scientific Instruments (30, 995), Irwin Wieder, a scientist personally trained by Maiman claimed that the quantum efficiency of Ruby was just 1%, not enough to attain a stimulated emission. And as per the calculations of Maiman, for a successful emission it should be 75%, an ardent but improbable objective! However, there was a silver-line that if he could have a very bright pump of light source, it could work. And the ‘eureka’ moment came from reading an article about photographic-lamps, which could achieve ‘brightness temperature’ of 8000K. Everything that had to follow was more easy with the help of his technical assistant Irnee d’ Haenens and on 16 May 1960 they got the first evidence of a LASER in action, the lifetime achievement of Maiman.

In Limelight? No!
In the euphoric days that followed, Maiman tried to refine his equipment and immediately prepared a report of his exciting results submitting it to Physical Review Letters on 24th June. However, the journal editor didn’t accept the paper, stating that the MASER-physics had already reached a mature state and “yet another MASER-paper” didn’t deserve rapid publication. [No wonder, Maiman’s invention was not ‘LASER’ then, it was only ‘optical-MASER’, as it was not Maiman but Gordon Gould, a graduate student at Colombia University who later named it as LASER]. Anyway, Maiman had to pen a shorter version of his original article and send it to Nature, where it was accepted (187, 493). It was scheduled for the 6th August issue of it, but Hughes Lab was anxious to conduct a press conference before that because since Bell Labs was involved in the race, there was no prize for a ‘runner up’! Thus the world came to know about it on July 7, 1960 which erased the long held conviction that LASER is not practically a possible thing. But many still continued to (or liked to!) disbelieve it. Though the potentialities of LASER were not known at that time, there was one more reason for Maiman not being in the lime light. On 1st August 1960, Shawlow and Townes at Bell Labs could reproduce Maiman’s result and got it published also in the same journal that rejected Maiman’s paper. It appeared in the October issue of Physical Review Letters and many who read it thought that Bell Laboratories was the first to build LASER. For the American scientific circles as well as public, Shawlow and Townes were familiar personalities and Bell Lab’s trials on LASER implementation was rather well known also. So, even after 50 years, the invention of LASER still remain controversial, atleast at the score boards of the rival fronts.

The LASER Revolution

The light of a LASER differ from that of an ordinary light source, iust like music differs from noice. Moreover, a LASER beam can travel kilometers without much increase in its diameter. For example, when a Ruby-LASER was sent to Moon from Earth, the spot it created on the surface of Moon was only 9 km, even after travelling 2,40,000 miles. Another quality of LASER is its immense luminous intensity. If we point our forefinger to sunlight, the power that falls on it is about one tenth of a watt. But, if light from LASER can be concentrated on it, it would be 109 watts. The size of a LASER device can be as big as a football field or as small as a pin-head. The light they emit can be invisible infrared, ultraviolet, X-ray or all the colours of the rainbow. The wavelength of some LASERs is tunable and their intensity can be amplified through several orders of magnitude. Some LASERs can’t even emit enough energy to cook an egg, where as certain others can vapourize steel! The pulse of a LASER can be as short as to last for a second (10-15s) while some others can create continuous beams that will remain for decades to come. However, many of these potentialities came through many years of research and in the beginning many entrepreneurs found that there were very few possibilities for commercial exploitation of LASERs. Many companies couldn’t even pursue definite applications from this field.
The next type of LASER that immediately followed Maiman’s Ruby-LASER was Helium-Neon-LASER developed by Bell Laboratories in the same year, 1960. But the first LASER that became the most prevalent type was the Diode-LASER made up of the semiconductor Gallium Arsenide. It soon mushroomed into a wide variety of commercial versions which still holds the global market. The first automated LASER scanning machine was used in a supermarket checkout-counter in Ohio in 1974 paving the way for a Universal Product Code (UPC). Called simply as the ‘bar-code’, it is used billions of times everyday by retailers and manufactures worldwide today. In late 1970s, the first trans-atlantic fibre-optic cables were laid down which became operating through diode-LASERs. They could deliver light into fibres with a few micrometers of core diameter and thus interconnecting the world in an integral way. The effect was a revolution in communication which sweeped Europe and US in late 1980s. In industry, there was yet another wonder that enabled metal cutting as easy as slicing a cake. It was the carbon dioxide-LASER that became a standardized cutting-tool even from 1970s. In automobile industry, it introduced a new technique such as “remote welding” which made multiple spot welds possible through “optical steering”. This opened a new opportunity for LASER to be used as weapons though such fancies were already there with the development of Maiman’s small LASER. But, rather than a “death ray”, its first military application was for range finding. The first target LASER designators was used in the Vietnam War, in 1972. It made bombs intelligent rather than being stupid by falling anywhere. Ronald Reagen’s ‘Star Wars’ programme was envisaging LASERs to be anti-missile weapons. Today these have become the norm for every country including India.

From the war-field, where the LASER directly entered was the music studio, one may hardly believe! In 1970s, Sony and Philips began developing music digitally recorded on shiny plastic discs that were 12 cm in diameter, popularly known as “Compact Discs” (CDs). The first digitalized music album came out as CD in 1982 with 74 minute of playback capacity –it was the album “52nd street” by Billy Joel. In the mid 1990s, the Digital Video Discs (DVDs) came which could store an entire feature length film. ‘Blue-ray Discs’ (BDs) were the next generation with 50 gigabyte capacity capable of holding more than five films in exceptionally high resolution. Simultaneously, beam-scanning systems were inverted which could dynamically follow music and trace intricate patterns in space. The first spectacular event by it was at “Expo 70” World Fair in Osaka, Japan. Rock concerts by bands like Pink Floyd usually employed them to evoke awe and surprise until restrictions came up due to safety reasons. In the field of medicine also, LASER heralded an authetic revolution. The first medical use of LASER was in 1961, when doctors at Columbia University of Medical Center in New York destroyed a retinal tumour by using a Ruby-LASER. Ophthalmology was the most benefited field where LASER was used for diagnosis as well as surgical cures. It enabled doctors to precisely vaporize a tissue or shapen it as they wish. A classical example is LASIK (LASER-Assisted in situ Keratomileusis) Surgery where LASER is used to reshape the cornea. In 1968, LASER proved to be a bloodless way to crush the kidney stone opening its potential towards guided surgeries. Now, it is routinely used to treat skin tumours as well as inaccessible brain tumours.

LASER in fiction
Imaginations about an invisible ray that could be used as a weapon was there is fiction before the principle of LASER was even thought of. The author who popularized it as a “death ray” was H.G. Wells, who in his 1898 tale ‘The War of the Worlds’ described it as an “inevitable, invisible sword of heat” that Martians use against the Earthlings. 1927, Alexey Tolstoy depicted a LASER-like devise in his science fiction novel ‘The Hyperboloid of Engineer Garin.’ Through the 1930s these predictions were well played in celluloid also. In his novel ‘Fatal Eggs’, Mikhail Bulgakov used it to create some “biological effects” on the target thought it was shown as a beam of red- light that emerges from an advanced microscope. In the 1951- film ‘The Day the Earth Stood Still’ LASER was the weapon the powerful robot uses. This was one of the reasons why the newspapers first quoted Maiman’s invention as “Death Ray” to the great dismay of him. In ‘Star Wars: Episode IV’ also the doomsday-fear was triggered using LASER. But, here it was not man but a distant star using LASER beams to destroy the Earth.

New Dawns

Let’s return to Einstein. In 1918 itself, he had predicted the existence of gravitational waves produced by moving masses. But until today, it has not beet directly detected. This is one of the research areas of future where LASER plays a part. The equipment used for this is an Interferometer which was first built in 1978 though much powerful versions are still in progress. These are dubbed LIGO-LASER Interferometer Gravitationalwave Observatory of which one is in Hanford and other in Livingston. Another is in Cascina in Italy officially known as VIRGO, which was opened in July 2003. Astrophysicist expect that LIGO and VIRGO may in someday detect Einstein’s dream waves. LASER was also there to realize Einstein another prediction which he did in 1924, about the existence of a special state of matter in which the so called bosons may be forced to stay in a state with identical quantum properties. In 1995, that state was achieved which was called Bose-Einstein Condensation. With it, it was possible to explore certain aspects of quantum mechanics and superconductivity, the classical epitomes of modern physics. Similar attempts are made by the National Ignition Facility, California where conditions akin to the heart of a star is created aiming to produce fusion power or the contrivances for it. The next telescopes are employing adaptive optics based on laser technology enabling astronomers to ascertain the position and movement of extrasolar planets. Yes, what we have is "Aladdin’s Lantern" and what we need yet is only the imagination to order things to do! And it is the real ‘problem’ created by LASER!


1. Perkowitz, Sidney (2010) “From Ray-gun to Blu-ray”. Physics World, May 2010, pp.16.20.

2. Rigby, Pauline (2010) “And then there was light”. Physics World, May 2010, pp. 23-27.

3. Fischer, Ernst Peter (2009) “Where only the new is considered, the old grows”.   LASER Community, February 2009. p.21.

4. CH Townes (1999) “How the Laser Happened”. Oxford University Press, New York.