The laser 1 is located on the focus of the collimator Lenses 2 and the laser beam is changed into the
parallel light. The parallel light beam is divided into two beams through the splitter prism 5. The reflection
light is focusing on the photodiode 3 OPT101 through the focus lens 4. The optical signal is converted into the
current signal 0 I as the original light intensity. The transmission beam is across the soot space 6. The