Optical sequencing is a single molecule DNA sequencing technique that follows sequence-by-synthesis  and uses optical mapping technology.  Similar to other single molecular sequencing approaches such as SMRT sequencing, this technique analyzes a single DNA molecule, rather than amplify the initial sample and sequence multiple copies of the DNA.  During synthesis, fluorochrome-labeled nucleotides are incorporated through the use of DNA polymerases and tracked by fluorescence microscopy.  This technique was originally proposed by David C. Schwartz and Arvind Ramanathan in 2003.