**4.5 Setup procedure to observe scattered signals**

Initially the following procedure was followed when measurements were taken at the remote sensing laboratory of the CCNY to assure the fiber's optimum alignment with respect to the lens. In this procedure, the laser pulses were shot at a hard target (100 m), and the scattered signal was obtained and monitored on the oscilloscope. **Figure 6** shows the scattered signal off a hard target in time domain. Maximizing the magnitude of the hard target's scattered signal through adjusting fiber's x, y, and z positions achieves the optimum fiber's location to focus the beam at about 100 m (the hard target's distance). To focus the beam at a different distance, the z position of the fiber holder can be adjusted accordingly. We then direct the laser beam away from the hard target to obtain atmospheric backscattering, **Figure 7.**
