Patent Number: 
Section: claims

1. A dual-energy ray scanning system, characterized in that said system comprises:a ray source for alternately emitting a high energy ray and a low energy ray;a filter comprising a low energy filtering element and a low energy transmitting element; anda control device for controlling said ray source and said filter to make said low energy filtering element of said filter be aligned with a beam exit direction of said ray source when said ray source emits a high energy ray so as to filter low energy portion of said high energy ray out and transmit high energy portion of said high energy ray out, and for controlling said ray source and said filter to make said low energy transmitting element of said filter be aligned with said beam exit direction of said ray source when said ray source emits the low energy ray so as to transmit said low energy ray out;wherein said low energy filtering element comprises a plurality of filter sheets;said low energy transmitting element comprises a plurality of transmission sheets;said filter sheets and said transmission sheets are arranged alternately and surround said ray source to form a cavity; andsaid ray source is located on a central axis of said cavity. 2. The dual-energy ray scanning system according to claim 1, characterized in that:said filter is a hollow cylinder shape; andsaid filter sheets and said transmission sheets are arranged parallel to said central axis of said cavity. 3. The dual-energy ray scanning system according to claim 1, characterized in that said filter sheets are equally sized and are arranged with equal distance each other. 4. The dual-energy ray scanning system according to claim 2, characterized in that said filter sheets are equally sized and are arranged with equal distance each other. 5. The dual-energy ray scanning system according to claim 1, characterized in that:said low energy filtering element is made of a high Z material; andsaid low energy transmitting element is a void or made of a low Z material,wherein Z represents an atomic number. 6. The dual-energy ray scanning system according to claim 1, characterized in that said ray source is an accelerator comprising a target and an electron gun for alternately emitting a high energy electron beam or a low energy electron beam, wherein said high energy electron beam bombards said target to generate a high energy ray and said low energy electron beam bombards said target to generate a low energy ray. 7. The dual-energy ray scanning system according to claim 1, characterized in that said ray source is an accelerator comprising an electron gun for emitting an electron beam and a target comprising a first part made of a first material and a second part made of a second material, wherein said electron beam emitted by said electron gun alternately bombard said first part or said second part of said target to respectively generate a high energy ray or a low energy ray. 8. A dual-energy ray inspecting system, characterized in that said dual-energy ray inspecting system comprises a dual-energy ray scanning system according to claim 1. 9. The dual-energy ray inspecting system according to claim 8, characterized in that said dual-energy ray inspecting system is a fix-mounted type dual-energy ray inspecting system, a movable type dual-energy ray inspecting system, or a vehicle-mounted type dual-energy ray inspecting system. 10. A dual-energy ray scanning method, characterized in that said method comprises:alternately arranging a plurality of filter sheets of a low energy filtering element of a filter and a plurality of transmission sheets of a low energy transmitting element of the filter to form a cavity;alternately emitting a high energy ray and a low energy ray by a ray source located on a central axis of the cavity; andcontrolling said ray source and a filter to make a low energy filtering element of said filter be aligned with a beam exit direction of said ray source when said ray source emits a high energy ray so as to filter low energy portion of said high energy ray out and transmit high energy portion of said high energy ray out, and to make a low energy transmitting element of said filter be aligned with said beam exit direction of said ray source when said ray source emits a low energy ray so as to transmit said low energy ray out. 11. The dual-energy ray scanning method according to claim 10, characterized in that said low energy filtering element is made of a high Z material, said low energy transmitting element is a void or made of a low Z material, wherein Z represents an atomic number. 12. A computer readable storage medium which stores a computer program, characterized in that said program is executed by a processor to implement said a dual-energy ray scanning method according to claim 10. 13. A computer device which comprises a memory, a processor, and a computer program which is stored in said memory and can be run by said processor, said computer device is characterized in that said processor executed said a dual-energy ray scanning method according to claim 10 by running said program.