ELECTRON OPTICAL APPARATUS, X-RAY EMITTING DEVICE AND METHOD OF PRODUCING AN ELECTRON BEAM

• US 20100020937A1
• Filed: 10/08/2007
• Published: 01/28/2010
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Hautmann, Stefan, Maring, Wolfram, Holzapfel, Steffen
• Granted Patent: US 7,839,979 B2
• Time in Patent Office: Days
• US Class Current: 378/137
• CPC Class Codes: H01J 35/147 Spot size control
• CPC Class Codes: H01J 35/153 Spot position control
• CPC Class Codes: H01J 35/30 by deflection of the cathode ray

Abstract

It is described an electron optical arrangement, a X-ray emitting device and a method of creating an electron beam. An electron optical apparatus (1) comprises the following components along an optical axis (25): a cathode with an emitter (3) having a substantially planar surface (9) for emitting electrons; an anode (11) for accelerating the emitted electrons in a direction essentially along the optical axis (25); a first magnetic quadrupole lens (19) for deflecting the accelerated electrons and having a first yoke (41); a second magnetic quadrupole lens (21) for further deflecting the accelerated electrons and having a second yoke (51); and a magnetic dipole lens (23) for further deflecting the accelerated electrons.

Claims

1. An electron optical apparatus (1) comprising the following components along an optical axis (25):

a cathode including an emitter (3), wherein the emitter has a substantially planar surface (9) for emitting electrons;

an anode (11) for accelerating the emitted electrons in a direction essentially along the optical axis (25);

a first magnetic quadrupole lens (19) for deflecting the accelerated electrons and having a first yoke (41);

a second magnetic quadrupole lens (21) for further deflecting the accelerated electrons and having a second yoke (51);

and a magnetic dipole lens (23) for further deflecting the accelerated electrons.

2. The apparatus according to claim 1, wherein the magnetic dipole lens (23) comprises dipole coils (57) arranged on the second yoke (51).

3. The apparatus according to claim 1, further comprising a scattered-electron-collector (31).

4. The apparatus according to claim 1, wherein each of the components has a symmetry with respect to the optical axis (25) and wherein the components are arranged co-axially with respect to the optical axis (25).

5. The apparatus according to claim 1, wherein the apparatus (1) has a length along the optical axis (25) of less than 90 mm.

6. The apparatus according to claim 1, wherein the planar surface (9) of the emitter (3) is non-structured.

7. The apparatus according to claim 1, wherein the planar surface (9) of the emitter (3) is finely structured.

8. An X-ray emitting device comprising the following components along an optical axis (25):

an electron optical apparatus (1) according to claim 1; and

an anode disc (7) arranged such that the accelerated electrons impact on an electron receiving surface of the anode disc (7).

9. The X-ray emitting device according to claim 8, wherein the anode (11) and the anode disc (7) are essentially on the same electric potential.

10. The X-ray emitting device according to claim 8, wherein the anode (11), the first magnetic quadrupole lens (19), the second magnetic quadrupole lens (21), the optional scattered electron collector (31) and the anode disc (7) are all connected to a water cooling circuit.

11. The X-ray emitting device according to claim 8, wherein a distance from the electron emitting surface (9) of the emitter (3) to the electron receiving surface of the anode disc (7) is less than 150 mm.

12. A medical X-ray device comprising an X-ray emitting device according to claim 8.

13. A method of creating an electron beam, the method comprising the steps of:

emitting electrons from a planar surface (9) of an emitter (3);

accelerating the electrons in a direction essentially parallel to an optical axis (25) using an anode (11);

deflecting the accelerated electrons using a first magnetic quadrupole lens (19);

further deflecting the accelerated electrons using a second magnetic quadrupole lens (21);

further deflecting the accelerated electrons using a magnetic dipole lens (23).