Laser 1960 – Light Amplification by Stimulated Emission of Radiation

Laser specialist Jeff Hecht wrote: 

“Laser technology plays an important role in practical applications ranging from medicine to electronics, telecommunications and military technology. 18 Nobel Prize winners have received their awards for laser-related research.”

The word laser comes from the process by which its light is produced. The English words are  Light  Amplification by the  Stimulated  Emission of  Radiation  (light amplification by stimulated emission of radiation), whose initials form the acronym laser.

In 1916, Albert Einstein proposed that, under suitable conditions, atoms could release excess energy as light, either spontaneously or when stimulated by light. 

In stimulated emission, a photon of suitable energy  (a particle of light) causes an electron to fall to a lower energy level, producing another photon. This second photon is correlated with the first and has the same phase, frequency, polarisation and direction of travel. If the photons are reflected repeatedly through the same atoms, amplification occurs and an intense radiation beam is emitted. Lasers can be constructed to emit electromagnetic radiation at various frequencies.

• In 1953, physicist Charles Townes and his students produced the first microwave laser  (maser), although it could not emit radiation continuously. 
• In 1960, Theodore Maiman created the first practical working laser. 
• In 1961, dermatologist Leon Goldman became the first to use a laser to treat melanoma  (a skin cancer). Related methods were later used to remove birthmarks and tattoos with minimal scarring. 

Examples of laser applications include:

• Because of the speed and precision of laser surgery, lasers are used in ophthalmology, dentistry and many other fields. 
• In LASIK eye surgery, a laser beam reshapes the cornea for short-sightedness and long-sightedness. 
• In prostate surgery, lasers can be used to vaporise tumours. 
• Green laser light absorbed by haemoglobin can be used to stop a bleeding blood vessel. 
• The hot beam of a surgical laser can be used to seal open blood vessels.

Description of the article image: An optical engineer studying laser interactions for potential use in laser weapon systems developed to defend against ballistic missile attacks

Historical figures mentioned in the article: Albert Einstein (1879–1955), Leon Goldman (1905–1997), Charles Hard Townes (b. 1915), Theodore Harold “Ted” Maiman (1927–2007)

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