Cool It, Hot Rod: Improving Early Lasers

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.