Device for realizing laser beam long distance precise focusing

The utility model provides a device for realizing laser beam long distance precise focusing. The device comprises a focusing device and an autofocusing device. The autofocusing device composed of an autofocusing shrink beam splitter, a hartmann microlens array and a CCD camera can detect the defocusing amount of an emitted laser beam real-timely and accurately, a translation stage can be controlled to carry a focusing beam expander secondary mirror to move along the optical axis of a focusing beam expander according to the detected defocusing amount, thereby achieving the purpose of laser beam long-distance precise focusing. The device for realizing the laser beam long distance precise focusing of the utility model is simple in structure, high in focusing precision, and convenient in use, does not need to calculate a focusing curve in advance, and is suitable for being applied to a long-distance high-precision laser focusing system.