Abstract: A differential pumping system includes a first chamber for storing a light source that emits pulsed light, a first exhaust unit for exhausting said first chamber, a second chamber being connectible to the first chamber to receive the pulsed light, a second exhaust unit for exhausting said second chamber, and a connection control mechanism between the first and second chambers for connecting the first chamber to the second chamber when the pulsed light emits, and for disconnecting the first chamber from the second chamber when the pulsed light does not emit.