Paul Kirkpatrick; Co-Inventor of X-Ray Microscope

Paul Kirkpatrick, co-inventor of the X-ray reflection microscope, has died, it was learned Tuesday.

A Stanford University spokesman said Kirkpatrick died in his sleep Saturday at his home on the Stanford campus, where he was professor emeritus of physics. He was 98.

Kirkpatrick was born into a family of homesteaders in Wessington, S.D. His parents moved to Los Angeles seeking better educational opportunities for their children. He received his undergraduate degree at Occidental College in Los Angeles and then spent two years teaching at a Presbyterian mission college in Hangchow, China, before returning to the United States during World War II to serve in the Army.

He received his doctorate, specializing in X-ray research, from UC Berkeley in 1923.

After six years at the University of Hawaii, Kirkpatrick went to Cornell University as a researcher. He joined the Stanford physics department in 1931.

Kirkpatrick’s work centered on reflected X-rays, and especially the Compton effect, which describes the reduction of energy in X-rays when they are scattered by free electrons.

In 1948, Kirkpatrick and graduate student Alfred Baez, singer Joan Baez’s father, developed the first X-ray microscope. The imaging technique is still used in medicine and astronomy.

Kirkpatrick retired in 1958, but continued to live with his family at their home on campus. He became a familiar figure around Palo Alto, with his white beard blowing in the wind as he rode his bike.

He is survived by his wife, Mary Rose, two daughters, nine grandchildren and 11 great-grandchildren.