Laser

noun (countable); also verb (transitive): to laser = to treat or cut with a laser

/ˈleɪzər/

A device that emits a concentrated, coherent, monochromatic beam of light through a process of stimulated emission of electromagnetic radiation (the acronym expands to Light Amplification by Stimulated Emission of Radiation). Lasers are used across a vast spectrum of applications: from consumer electronics (barcode scanners, fibre optic communications) to medical surgery (ophthalmology, oncology), precision manufacturing, atomic clocks, LIDAR (laser-based remote sensing), and directed-energy weapons. In UPSC context, DRDO's Aditya laser-based directed energy weapon, NavIC's laser ranging for satellite precision, ISRO's LIDAR instruments on lunar missions, and FELUDA's CRISPR-based COVID diagnostic (which uses a fluorescent detection step analogous to laser-probe technology) are all examined in GS3.

✍️ Usage in a UPSC answer

ISRO's Chandrayaan-3 lander carried a Laser Retroreflector Array (LRA) provided by NASA — an instrument that enables Earth-based lasers to precisely measure the Moon's distance and the lander's exact position, demonstrating the complementarity of bilateral space cooperation even under strategic competition.

Synonyms

coherent light beamoptical beamlight amplifieroptical maser (archaic)

Antonyms

incoherent lightdiffuse radiationincandescent light

🌱 Word Family

laser (n/v), lasing (v/adj), laser beam (n phrase), LIDAR (n, Light Detection And Ranging), laser ablation (n phrase), laser-guided (adj), maser (n, microwave precursor)

🔡 Root

Acronym: Light Amplification by Stimulated Emission of Radiation — coined 1957 by Gordon Gould; underlying physics from Albert Einstein's 1917 theory of stimulated emission

📜 Etymology

The acronym LASER was coined by American physicist Gordon Gould in 1957 (in a notarised notebook), building on the earlier MASER (Microwave Amplification by Stimulated Emission of Radiation) developed by Charles Townes et al. in 1953–54. The first working laser was built by Theodore Maiman in 1960 using a synthetic ruby crystal. The theory of stimulated emission on which lasers rest was published by Albert Einstein in 1917.

🧠 Memory Hook

LASER = Light Amplification by Stimulated Emission of Radiation. Use the chain: Einstein 1917 (theory) → Maiman 1960 (first laser, ruby crystal) → DRDO Aditya (India's DEW). The word is an acronym that became a common noun — like radar and sonar. 'Stimulated emission' is the core physics: one photon triggers another aligned photon.

📝 Seen in UPSC Question Papers

Prelims 2025 — Internal Security
Prelims 2020 — Internal Security
Prelims 2017 — Space Technology
Prelims 2017 — Space Technology

Real UPSC previous-year questions whose text uses “Laser” — proof this word earns its place on your list.

🔬 Science & Technology 📖 Seen in: Emerging Technologies — AI, Quantum Co...

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