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Juggling with numbers
Published in Breach Mark, Essential Maths for Engineering and Construction, 2017
Time is a useful way of dealing with enormous distances. Light travels at about 300 000 kilometres per second. Light-time is the distance that light travels in a given time, so a light second is 300 000 km. That means that the distance from:
Effects of heterodyne signals on femtosecond optical Kerr measurements
Published in Journal of Modern Optics, 2019
It should be noted that and are the phase changes of the components of the probe field that polarized parallel and perpendicular to the pump field, respectively. They are both induced by two factors: first, the pump beam induced nonlinear refractive index changes in the overlapping region of the pump and probe light; second, the probe beam itself induced nonlinear refractive index changes in the whole optical path in the sample. As is always zero, the value of is mainly determined by the pump power and the interaction length of the pump and probe light. As the probe light-induced phase changes could be much larger, because the interaction length of the probe light in the sample is much longer and the interaction length of the pump and probe light is very short. Therefore, the intensity of the heterodyne signal expressed by the second term in Equation (5) can be comparable with that of the OKE signals, although the leakage of analyser could be very small. The influence of the heterodyne signal on the OKE measurements could be significant, which can be expressed by the ratio of the heterodyne signal to Kerr signal: From the equations given above, we can see that the leakage of the probe light will introduce a modulation of polarization dependence of the OKE signals, and the experimental results will well verify our calculations.