Sir Alan Walsh FAA FRS (19 December 1916 – 3 August 1998) was a British-Australian physicist, originator and developer of a method of chemical analysis called atomic absorption spectroscopy.

He was the eldest son of Thomas Haworth Walsh, cotton mill manager, and Betsy Alice (née Robinson).

On graduation in 1938 he was also awarded a research scholarship, which he took up in the physics department, where he was particularly influenced by Henry Lipson’s suggestion that he work on the structure of β-carotene.

[4] While developing the method he discovered that it could not always be transferred uniformly from one laboratory to another, so he set about devising a General Purpose Source Unit.

After a long delay, he was offered the job in March 1946, but he first had to spend 3–4 months in Gordon Sutherland’s lab in Cambridge, to gain experience in the new field of infrared molecular spectroscopy.