The paperless office clearly is an illusion as people continue to print and photocopy incredible amounts of emails, memos and other useless documents that end up in the bin. So if we cannot get rid of paper in the office, maybe we can remove the ink from it and then use the paper again?


An engineering team at the University of Cambridge in the UK has figured out how to erase pages by vaporizing common toners using a laser-based technique that doesn't damage the underlying paper. The key idea was to find a laser energy level that is high enough to vaporize the toner without destroying the paper on which it is fixed. After many experiments it was found that 4-ns pulses with a wavelength of 532 nm (green light) worked best.


The researchers were able to repeat the printing/unprinting process three times on the same piece of paper with good results. The team has found toner-paper combinations in which almost no appreciable traces of toner can be seen after lasing and in which the paper suffers no significant mechanical damage.