> If they had two lasers of similar frequencies they would get interference beats/aliases in the data.
1. They did use different frequencies- 1540 nm and 1550 nm.
2. The measuring was done with doppler interferometry, so beats would not impact measurements. The sensor is only responding to the difference between two signals, not the intensity.
3. 10 nm wavelength shift is a much larger difference than anything they'd be measuring, so the only thing that would actually even "show up" (as noise) would be light at the same wavelength as the measuring laser. Any constant noise at the same wavelength as the measuring laser will be filtered out. Only slight frequency deviations would come through- like the kind from vibrations shaking the laser.
1. They did use different frequencies- 1540 nm and 1550 nm.
2. The measuring was done with doppler interferometry, so beats would not impact measurements. The sensor is only responding to the difference between two signals, not the intensity.
3. 10 nm wavelength shift is a much larger difference than anything they'd be measuring, so the only thing that would actually even "show up" (as noise) would be light at the same wavelength as the measuring laser. Any constant noise at the same wavelength as the measuring laser will be filtered out. Only slight frequency deviations would come through- like the kind from vibrations shaking the laser.