Frequency-based optical spectroscopy Trevor J. Sears 649.00 649.50 650.00 Frequency – 195 739 000.00 MHz Frequency comb-based techniques are going to revolutionize many aspects of spectroscopy in the next decade. Top figure shows a measurement of the P(11) line in the 1.5 micron band of C2H2 with accuracy and precision of 4x1011. Lower figure shows a nitrogen pressure broadened measurement of same line at 240K. The inset is a plot of the residuals following a fit to a model function showing the quality of the data.