Collector for weak light in three-dimensional space

The invention relates to an optical device, and discloses a collector for weak light in a three-dimensional space. The collector comprises an ellipsoid reflector, a spherical reflector and a plane reflector, the ellipsoid reflector and the spherical reflector are both concave reflectors, the concave face of the ellipsoid reflector faces the concave face of the spherical reflector, and thus a cavity is formed. The circle center of the spherical reflector is superposed with one focus of the ellipse in the ellipsoid reflector, the reflecting face of the plane reflector is located at the central point of the connecting line of the two focuses of the ellipse of the ellipsoid reflector, and the area of the plane reflector is one fifth to one third that of the circle at the latus rectum of the ellipse in the ellipsoid reflector. The special structure is adopted in the collector for the weak light in the three-dimensional space, and thus weak light such as fluorescent light of trace materials excited by laser beams a