In the experiment setup, the pulse laser and the rotating ground glass form a pseudo thermal light source. Compared to
the thermal light source, the pseudo thermal light is more suitable for ghost imaging experiment. On the one hand, the
coherence time of thermal light source is 10-11 s to 10-10 s which is less than the response time of the photo detector; On
the other hand, the brightness of thermal light source is very low, it is very hard to detect the intensity fluctuation. In 1964, Martienssen invented a pseudo thermal light source which can simulate statistical properties of thermal light [6]. In 1960s-1980s, several research about the pseudo thermal light were presented [7-10]. The new light source makes a laser beam pass through a rotating ground glass. The coherence time of light can be set from 10-5s to 1s by adjusting the rotation rate of the ground glass, which can match the response time of the detector. However, the laser in [6] is continuous laser whose brightness is limited. In order to improve the brightness of the light source, the pulsed laser was recommended to take the place of the continuous laser [11].