**3.4 Experimental measurement**

The thrust of the thruster with known parameters is measured to further verify the accuracy of the measurement method. The overall test device is shown in **Figure 8**. The thruster is installed on one side of the torsion pendulum. When the thruster works, its impulse will act on the torsion pendulum system. When the thruster works, its impulse will act on the swing arm and drive the torsion bar to rotate; The reflector installed on the swing arm reflects the laser beam emitted by the He-Ne laser to the remote PDS photosensitive surface; With the action of the impulse, the light spot produces a small displacement on the PDS photosensitive surface, which makes the PDS produce a small voltage signal output.

The measurement results of micro and thrusts and impulses are shown in **Tables 1** and **2**. According to the results in the table, this measuring device can realize the measurement of thrust and impulse of microns. At the same time, the resolution of PDS can be further improved and more sensitive materials can be selected to excavate higher resolution. In theory, this measuring device can achieve at least 100 nN and 100 nN�s measurements.
