= C. Kumar N. Patel
{c}
{title2=born 1938}
{wiki}
= C. K. N. Patel
{c}
{synonym}
\b[C. Kumar N. Patel] developed the <carbon dioxide laser> at Bell Laboratories. His National Inventors Hall of Fame record identifies the contribution and records his birth in 1938, education in India and at Stanford, and induction in 2012.<C. Kumar N. Patel at the National Inventors Hall of Fame>[Named inventor biography and education]{ref} UCLA's faculty record uses the Kumar form and lists a Stanford doctorate in 1961; its publication list preserves the C.K.N. Patel byline.<C. Kumar Patel faculty profile at UCLA>[Educational Background and Selected Publications]{ref}
His 1964 experiment showed continuous <laser> action on rotational transitions within molecular vibrational bands of <carbon dioxide>, rather than only on <atomic transitions>. The strongest reported line was $10.6324\,\mathrm{\mu m}$ in vacuum, with about $1\,\mathrm{mW}$ continuous output.<Continuous-Wave Laser Action on Vibrational-Rotational Transitions of CO2 by C. K. N. Patel>[Abstract and Table I]{ref} <Molecular vibration> and <molecular rotation> therefore provide the energy-level structure behind the observed <infrared> lines.
The apparatus made those invisible lines measurable. The paper describes a five-metre <quartz> tube with an <electrical discharge>, a nearly <confocal optical cavity> formed by <silicon> <mirrors> with <aluminium> coatings, and output coupled through an uncoated central mirror aperture. A <copper>-doped <germanium> <photoconductor> cooled to $4.2\,\mathrm K$ detected the radiation; a <thermopile> checked power, and a scanning grating <spectrometer> measured wavelengths.<Continuous-Wave Laser Action on Vibrational-Rotational Transitions of CO2 by C. K. N. Patel>[§II, pp. A1187–A1188, Experimental Technique]{ref} Electrical excitation, resonator feedback and infrared detection play separate roles in that observation.
An original calculation connects the recorded wavelength to familiar quantum scales. Using the <Planck constant> and vacuum <speed of light>,
$$
\nu=\frac{c}{\lambda}\simeq2.8196\times10^{13}\,\mathrm{Hz},\qquad E_\gamma=\frac{hc}{\lambda}\simeq0.11661\,\mathrm{eV}.
$$
Treating a $1\,\mathrm{mW}$ output as monochromatic at that line gives \b[$P/E_\gamma\simeq5.35\times10^{16}$ photons per second]. This is a derived scale estimate, not a photon-count measurement from the paper. <Photon energy> and total <radiant flux> are different quantities.
The Hall of Fame records the later importance of <carbon dioxide lasers> for industrial cutting, welding, engraving and drilling.<C. Kumar N. Patel at the National Inventors Hall of Fame>[Industrial applications]{ref} That engineering reach explains why a small early molecular-laser demonstration became historically significant.
\Image[https://www.invent.org/sites/default/files/styles/inductee_media/public/inductees/2022-06/patel_1_edited%20for%20web.jpg?h=475d4c8c]
{title=<C. Kumar N. Patel>}
{description=Named headshot on the https://www.invent.org/inductees/c-kumar-n-patel[National Inventors Hall of Fame profile]. External image, not stored in this repository.}
{height=300}
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