Vacuum particle counter

The invention relates to a vacuum micro-particle counter which comprises a shell; the shell is provided with a measuring hole penetrating through the shell in the z direction, and the interior of the shell is fixedly provided with light incident parts, light detection parts and a light emitting part; the light incident parts are used for emitting laser and forming a flat-topped light beam with the cross section light intensity evenly distributed, are located on one side of a measuring hole, and each comprise a laser device, an incident optical element set and an incident diaphragm which are sequentially arranged in the x direction; incident optical element groups each comprise a focusing lens, a light homogenizing rod and a lens group which are sequentially arranged along the x direction; the light detection parts collect scattered light formed by scattering the flat-topped light beam by the micro-particles and detect the number of the micro-particles on the basis of the collected scattered light; and the lig