The words "10-22-38 Astoria" are printed on a microscope slide, under the strong light of sulfur. After the slides were taken away, the mirror images of those words were left on the sulfur. Carlson intends to sell his invention to some companies, but the process is not mature enough to achieve results.
Invention:
Chester Carlson, the inventor of the copier, was originally a patent lawyer, part-time researcher and inventor. His job in new york Patent Office requires copying many important documents. Carlson suffers from arthritis and regards copying documents as a painful and monotonous job.
This encouraged him to conduct photoconductivity experiments and estimated that he could copy them in the simplest way. Carl Johnson conducted an electrophotographic experiment in his kitchen, and applied for a technology patent at 1938. He made the first replica from zinc sheets covered with sulfur. He made the first "copier" from zinc plates covered with sulfur.