Xerox/Laurie Riedman
That was exactly 75 years ago.
Carlson spent his life coming up with crazy
How did he do it?
The idea behind xerography is all about light and electrical charges. According to Xerox.com, by placing an image on an electrical conductor and then exposing it to light, you can create a copy. The illuminated areas - the blank areas of whatever you are copying - become more conductive after exposure to the light. This makes the actual image part of whatever you are copying have a positive charge.
After a year of experimentation in the kitchen of his apartment, that included several small fires and an angry wife, Carlson was successful.
A negatively charged powder is then spread over the copy and it sticks to the positively charged images. A piece of paper is placed over the powder image, the powder is fused to the paper using heat, and you get your copy.
Carlson and his assistant, a formerly unemployed physicist named Otto Kornei, used a zinc plate coated in sulfur as an electric conductor. They rubbed the sulfur with a cotton handkerchief to generate a positive electric charge.
Kornei wrote the date and location, 10-22-38 ASTORIA on a microscope slide and then laid it on the zinc plate. After exposing the slide to a bright light, they removed the plate and dusted it with powder. A copy of the image 10-22-38 ASTORIA showed up on the plate - the world's very first xerox. Here's what it looked like:
Xerox/Laurie Friedman
Luckily for Carlson he also worked as a patent lawyer and actually became very wealthy from his invention. But he still lived very simply and near the end of his life he gave away most of the fortune he earned from Xerox.
You can check out one of the earliest xerox commercials from 1964 and see how some of the earliest machines worked:
According to Smithsonian magazine, the world will produce upwards of 3 trillion xerographic copies this year.