A COLLECTION OF FIRST PRINTINGS OF PAPERS DOCUMENTING THE MAJOR MILESTONES IN THE FIRST DECADE OF THE DEVELOPMENT OF THE MASER AND LASER, starting with the invention of the maser in 1954, through the invention of the laser four years later, up to the award of the Nobel Prize in Physics in 1964 to Townes, Basov and Prokhorov for their work on masers and lasers.
“‘Laser’ is an acronym for Light Amplification by Stimulated Emission of Radiation. It describes any device that creates and amplifies a narrow, focused beam of light whose photons are coherent. In a laser, the atoms or molecules of the lasing medium–either a crystal like ruby or garnet, or a gas or liquid–are ‘pumped,’ so that more of them are at higher energy levels than at the ground state.
“The end result is a sudden burst of coherent light as the atoms discharge in a rapid chain reaction. This process is called ‘stimulated emission.’ Albert Einstein first broached the possibility of stimulated emission in a 1917 paper, having turned his attention the year before from general relativity to the interplay of matter and radiation, and how the two could achieve thermal equilibrium. Einstein devised an improved fundamental statistical theory of heat, embracing the quantum of energy.
“First, Einstein proposed that an excited atom in isolation can return to a lower energy state by emitting photons, a process he dubbed spontaneous emission. Spontaneous emission sets the scale for all radiative interactions, such as absorption and stimulated emission. Atoms will only absorb photons of the correct wavelength: the photon disappears and the atom goes to a higher energy state, setting the stage for spontaneous emission. Second, his theory predicted that as light passes through a substance, it could stimulate the emission of more light.
“Einstein postulated that photons prefer to travel together in the same state. If one has a large collection of atoms containing a great deal of excess energy, they will be ready to emit a photon randomly. However, if a stray photon of the correct wavelength passes by (or, in the case of a laser, is fired at an atom already in an excited state), its presence will stimulate the atoms to release their photons early–and those photons will travel in the same direction with the identical frequency and phase as the original stray photon. A cascading effect ensues: as the crowd of identical photons moves through the rest of the atoms, ever more photons will be emitted from their atoms to join them (www.aps.org/publications/apsnews/200508/history.cfm).
“In 1917, Einstein proposed the process that makes lasers possible, called stimulated emission. He theorized that, besides absorbing and emitting light spontaneously, electrons could be stimulated to emit light of a particular wavelength. But it would take nearly 40 years before scientists would be able to amplify those emissions, proving Einstein correct and putting lasers on the path to becoming the powerful and ubiquitous tools they are today.
The collection includes:
1. GORDON, J. P., ZEIGER, H. J. & TOWNES, C. H. ‘Molecular microwave oscillator and new hyperfine structure in the microwave spectrum of NH3,’ pp. 282-4 in Physical Review Vol. 95, No. 1, July 1, 1954. Original printed wrappers.
2. GORDON, J. P., ZEIGER, H. J. & TOWNES, C. H. ‘The maser – new type of microwave amplifier, frequency standard, and spectrometer,’ pp. 1264-74 in Physical Review Vol. 99, No. 4, August 15, 1955. Original printed wrappers, former owner’s name on top left corner of front wrapper.
3. BASOV, N. G. & PROKHOROV, A. M. ‘Theory of molecular oscillator and a powerful molecular amplifier [Russian],’ pp. 47-49 in Doklady Akademii Nauk SSSR, Vol. 101, No. 1, 1955. Original printed wrappers, embossed stamp on upper wrapper. Very rare.
4. BLOEMBERGEN, N. ‘Proposal for a new type solid state maser,’ pp. 324-7 in Physical Review Vol. 104, No. 2, October 15, 1956. Original printed wrappers.
5. SCHAWLOW, A. L. & TOWNES, C. H. ‘Infrared and optical masers,’ pp. 1940-9 in Physical Review Vol. 112, No. 6, 1958. Original printed wrappers.
6. MAIMAN, T. H. ‘Stimulated optical radiation in ruby,’ pp. 564-6 in Physical Review Letters, Vol. 4, No. 11, 1960. Original printed wrappers.
7. GOLDENBERG, H. M., KLEPPNER, D. & RAMSEY, N. F. ‘Atomic hydrogen maser,’ pp. 361-2 in Physical Review Letters Vol. 5, No. 8, October 15, 1960. Original printed wrappers.
8. HALL, R. N., FENNER, G. E., KINGSLEY, J. D., SOLTYS, T. J. & CARLSON, R. O. ‘Coherent light emission from Gas junctions,’ pp. 366-8 in Physical Review Letters Vol. 9, No. 9, November 1, 1962. Original printed wrappers.
9. PATEL, C. K. N. ‘Interpretation of CO2 optical maser experiments,’ pp. 588-90 in Physical Review Letters Vol. 12, No. 21, 25 May 1964. Original printed wrappers, address label on rear wrapper.
Timeline and descriptions:
April 26, 1951: Charles Hard Townes of Columbia University in New York conceives his maser (microwave amplification by stimulated emission of radiation) idea while sitting on a park bench in Washington.
1954: Working with Herbert J. Zeiger and graduate student James P. Gordon, Townes demonstrates the first maser at Columbia University. The ammonia maser, the first device based on Einstein’s predictions, obtains the first amplification and generation of electromagnetic waves by stimulated emission. The maser radiates at a wavelength of a little more than 1 cm and generates approximately 10 nW of power. [1, 2]
1955: At P.N. Lebedev Physical Institute in Moscow, Nikolai G. Basov and Alexander M. Prokhorov attempt to design and build oscillators. They propose a method for the production of a negative absorption that was called the pumping method. “The first masers used a method of selecting the more excited molecules from a beam, but a more efficient method was proposed by Basov and Prokhorov in 1955, the so-called ‘three- level’ method of producing population inversion by ‘pumping’ with a powerful auxiliary source of radiation. The next year the method was applied by Nicolaas Bloembergen in America in a quantum amplifier” (Oxford Dictionary of Scientists, under Basov). 
1956: Nicolaas Bloembergen of Harvard University develops the microwave solid-state maser. “Bloembergen’s early research on nuclear magnetic resonance led him to an interest in masers. He designed a three-stage crystal maser that was dramatically more powerful than earlier gaseous masers and that has become the most widely used microwave amplifier” (Britannica). Solid-state masers of Bloemberg’s design were used in the detection of the cosmic microwave background by A. Penzias and R. Wilson in 1965. Bloembergen shared the 1981 Nobel Prize for Physics for his “contribution to the development of laser spectroscopy.” 
1958: Townes, a consultant for Bell Labs, and his brother‑in-law, Bell Labs researcher Arthur L. Schawlow, in a joint paper published in Physical Review, show that masers could be made to operate in the optical and infrared regions and propose how it could be accomplished. The invention of the laser. 
May 16, 1960: Theodore H. Maiman, a physicist at Hughes Research Laboratories in Malibu, Calif., constructs the first operational laser using a cylinder of synthetic ruby measuring 1 cm in diameter and 2 cm long, with the ends silver-coated to make them reflective and able to serve as a Fabry-Perot resonator. Maiman uses photographic flashlamps as the laser’s pump source. 
October 1960: At Harvard University, Daniel Goldenberg, Mark Kleppner and Norman Ramsey construct the first atomic hydrogen maser, based on the transition between the state in which the proton and electron in a hydrogen atom have spins in opposite direction to that in which the spins are aligned. It provides one of the best fundamental standards of frequency (or time): its output is a radio wave whose frequency of 1,420,405,751.786 hertz (cycles per second) is reproducible with an accuracy of one part in 30 × 1012. 
1962: At General Electric in Schenectady in New York, Robert Hall and four part‑time collaborators, Gunther Fenner, Jack Kingsley, Ted Soltys and Richard Carlson, develop the first semiconductor laser. “The invention of the semiconductor laser took lasers from the scientist’s lab and action hero’s arsenal to every living room DVD player and grocery store scanner. It began with the serendipitous discovery in 1962 that gallium arsenide could be made to produce surprisingly intense light. Later that year, the first gallium arsenide laser was reported in Physical Review Letters. The modern descendants of that device are the tiny lasers that abound in countless modern appliances” (physics.aps.org/story/v26/st3). 
1964: The carbon dioxide laser is invented by Kumar Patel at Bell Labs. The CO2 laser has more practical applications today than any other type of laser. In the hard sciences, it has improved high-resolution and saturation spectroscopy; contributed to laser-induced fusion and nonlinear optics; and is even used for the optical pumping that has made possible newer types of lasers (e.g., far‑infrared and x‑ray). In industry, the CO2 laser is used in many forms of welding, cutting and drilling, including those at the micromechanical level, of materials ranging from diamonds to cigarette filters. In medicine, its primary use is in laser surgery, including the removal of tumors and various noncontact and noninvasive procedures. Among military applications, its most striking contribution has been to the ʺStar Wars" system once promoted by Ronald Reagan and still being developed today. 
1964: Townes, Basov and Prokhorov are awarded the Nobel Prize in physics for their “fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser-principle”” (Timeline mostly taken from: M. Rose, A History Of The Laser: A Trip Through The Light Fantastic, www.photonics.com/Article.aspx?AID=42279).