Laser is an acronym for
Light Amplification by Stimulated Emission of Radiation.
Taser is an acronym too, but has nothing to do with
laser. It's named after a novel.
The taser was invented by a NASA scientist called
Jack Cover who worked on it between 1969 and 1974. He had been inspired by a series of children's books about a hero called Tom Swift. Tom Swift is an adventuring sort of chap who goes around having adventures, sometimes in darkest, deepest Africa and sometimes on the Moon. There have been over a hundred
Tom Swift books published since 1910 and they still seem to be going strong, there was even a Tom Swift board game once. However, the one that interests us is the tenth in the series which was published in 1911:
Tom Swift and his Electric Rifle. In this one Tom Swift goes elephant hunting when he discovers that some of his friends have been taken hostage by a tribe of red pygmies. Luckily for the hero (but unluckily for the red pygmies) Tom has with him his brand new invention: a rifle that uses electricity rather than bullets. It can therefore be set to different ranges and different levels of lethality, so he can stun elephants, kill pygmies etc.
It was this invention that Jack Cover was attempting to imitate, and he even decided to call it Tom Swift's Electric Rifle, or TSER. However, as that didn't make a catchy acronym he decided to add a gratuitous initial and make it
Thomas A. Swift's Electric Rifle, or TASER.