Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Cool It, Hot Rod: Improving Early Lasers

Merritt Birky in white shirt and tie leaning over and measuring laser rod distortion
Credit: NIST Digital Collections

Merritt Birky measuring laser rod distortion at NIST in 1969.

In the first decade after the invention of the laser one challenge to improving laser quality was the distortion of a laser’s rod due to absorption of heat during lasing. The heat absorption distorted the rod’s optical characteristics, which reduced the quality of a laser’s beam. In 1969 NIST’s Merritt Birky developed a technique to measure the internal stresses on laser rods during lasing, leading to a better understanding of complex active laser characteristics and to improved laser rod construction.

Released May 1, 2017, Updated May 2, 2017