Optical element with light-splitting function

An optical element with light-splitting function, comprising:

• a lens component including first, second and third planes disposed to surround and parallel to a reference axis, said first plane being formed with a first collimating unit and a second collimating unit that is spaced apart from said first collimating unit, said second plane being formed with a third collimating unit, said third plane being formed with a groove extending along and indented toward said reference axis, said groove being defined by a fourth plane and a fifth plane, said fourth plane extending obliquely relative to said first plane;
• and
• a reflecting mirror disposed on said third plane to cover said groove and having a reflecting plane facing said fourth and fifth planes,
• wherein, when a light beam incident from said first collimating unit propagates within said lens component along a first optical path to reach said fourth plane, one part of the light beam is reflected by said fourth plane toward said second collimating unit and propagates along a monitoring optical path to exit said lens component, and the other part of the light beam enters, by refraction through said fourth plane, and propagates within said groove to be reflected by said reflecting plane of said reflecting mirror, followed by entering, by refraction through said fifth plane, and propagating within said lens component along a second optical path toward said third collimating unit to exit said lens component.