OPTICAL DEFLECTION DEVICE FOR SCANNING, OPHTHALMOLOGIC MEASUREMENT AND THERAPY SYSTEM

• US 20110069366A1
• Filed: 09/20/2010
• Published: 03/24/2011
• Est. Priority Date: 09/18/2009
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec AG (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss Meditec AG (Carl-Zeiss-Stiftung)
• Inventors: Ebersbach, Ralf, Weigand, Heino, Hacker, Martin, Pabst, Thomas, Antkowiak, Gerard
• Granted Patent: US 8,736,935 B2
• Time in Patent Office: Days
• US Class Current: 359/200.7
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 3/1225 using coherent radiation
• CPC Class Codes: A61F 2009/00851 Optical coherence topography [OCT]
• CPC Class Codes: A61F 2009/00897 Scanning mechanisms or algorithms
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/10 Scanning systems

Abstract

An optical deflection unit for targeted radiation, e.g., produced by laser or superluminescent diodes, in scanning, ophthalmological measuring and therapy systems, comprises a deflection mirror, a position sensor and a control unit, which form a control circuit for minimizing the deviation of the actual positions, detected by the position sensor, from the desired positions of the deflection mirror, whereby the optical deflection unit comprises a deflection mirror, oscillatingly movable by means of non-contacting electromagnetic drives around at least one rotation axis, and which is positioned in the direction of the, at least, one rotation axis between at least two bearings. The optical deflection unit is designed may also be used for beam guidance in high and ultrahigh vacuum installations, such as UV and EUV exposure installations for semiconductor lithography.

Claims

1. An optical deflection unit for scanning, ophthalmological measuring, and therapy systems comprising a deflection mirror, oscillatingly movable through non-contacting electromagnetic drives around at least one rotation axis, and which is arranged between at least two bearings in the direction of the at least one rotation axis, a position sensor, and a control unit, the deflection mirror, the position sensor, and the control unit forming a control circuit for minimizing the deviation of the actual positions, detected by the position sensor, from the desired positions of the deflection mirror.

2. The optical deflection unit, according to claim 1, wherein the deflection unit comprises a housing with a frame, oscillatingly movable around a rotation axis, which holds the deflection mirror, and which is secured in the housing via two bearings and which exhibits permanent magnets, and whereby the deflection unit exhibits in the housing non-contacting, electromagnetic drives in the form of electromagnets, which face the permanent magnets.

3. The optical deflection unit, according to claim 1, wherein the frame, which is oscillatingly movable around a rotation axis in the housing, is further pivoted around an additional rotation axis, whereby the two rotation axes lie orthogonally to one another.

4. The optical deflection unit, according to claim 1, wherein the deflection unit comprises a housing with two movable frames, whereby the inner of the two movable frames holds the deflection mirror, exhibits permanent magnets, and is secured via two bearings in the outer movable frame, which also exhibits permanent magnets and is secured via two bearings in the housing, and whereby the deflection unit exhibits in the housing non-contacting, electromagnetic drives in the form of electromagnets, which face the permanent magnets.

5. The optical deflection unit, according to claim 1, wherein the deflection unit comprises a housing with two movable frames, whereby the inner of the two movable frames holds the deflection mirror, exhibits permanent magnets, preferably arranged in pairs, for both rotation axes and is secured via two bearings in the outer movable frame, which, in turn, is secured via two bearings in the housing, and whereby the deflection unit exhibits in the housing non-contacting, electromagnetic drives in the form of electromagnets, which face the permanent magnets.

6. The optical deflection unit, according to claim 1, wherein electromagnets in the form of air-coned coils or plunger coils are used as non-contacting electromagnetic drives.

7. The optical deflection unit, according to claim 2, wherein the deflection mirror is detachably connected with a movable frame.

8. The optical deflection unit, according to claim 4, wherein the movable frames as well as the arrangement of the permanent magnets are symmetrical to the rotation axes, whereby the permanent magnets are preferably arranged in pairs on the rotation axis.

9. The optical deflection unit, according to claim 1, wherein the mirror has a plane, and wherein the movable frame, which holds the deflection mirror, is secured in the housing in such a way that the rotation axis (axes) lie in the mirror plane.

10. The optical deflection unit, according to claim 2, wherein at least one of lubrication-free flexural pivots and pretensioned hybrid ball bearings are used as bearings for the movable frame.

11. The optical deflection unit, according to claim 1, wherein the control of the non-contacting, electromagnetic drives in the form of electromagnets is effected digitally for the realization of the scan pattern transmitted by the pattern generation.

12. The optical deflection unit, according to claim 11, wherein the control of the non-contacting, electromagnetic drives in the form of electromagnets is effected through pulse modulation.

13. The optical deflection unit, according to claim 1, wherein an optical, position-selective, two-dimensional sensor is used as position sensor for the detection of the actual positions of the deflection mirror and upon which the light of an additional light source is mapped for position detection via the deflection mirror.

14. The optical deflection unit, according to claim 1, wherein the optical position sensor operates in accordance with the intensity focus principle.

15. The optical deflection unit, according to claim 1, wherein a plane-convex lens and/or a neutral density filter or an aperture with beam trap for minimizing scattered light influences can be positioned before the optical position sensor.

16. The optical deflection unit, according to claim 1, wherein the optical position sensor and the additional light source for position detection are arranged in such a way that its light beam falls onto the deflection mirror laterally to the light beam of the light source for the realization of the measurement and therapy tasks.

17. The optical deflection unit, according to claim 1, wherein the light beam for position detection and the light beam for the realization of the measurement and therapy tasks exhibit different wavelengths or polarization states or fall from different directions onto the same spot on the deflection mirror.

18. The optical deflection unit, according to claim 17, wherein a wavelength-selective or polarization-selective filter is positioned before the optical position sensor and which exhibits a lower transmission for the light beam for the realization of the measurement and therapy tasks than for the light beam for position detection.

19. The optical deflection unit, according to claim 1, wherein the light beam for position detection and the light beam for the realization of the measurement and therapy tasks fall from orthogonal directions onto the same spot on the deflection mirror.

20. The optical deflection unit, according to claim 1, wherein an LED, which radiates a light beam of low divergence, is used as light source for position detection.

21. The optical deflection unit, according to claim 1, wherein a filter and/or a pinhole can be positioned in front of the light source for position detection.

23. The optical deflection unit, according to claim 4, wherein the housing of the deflection unit exhibits devices for damping the movements of the movable frames when not in use.

24. The optical deflection unit, according to claim 4, wherein the electromagnets, functioning as non-contacting, electromagnetic drives, are used for damping of the movement of the movable frames, whereby they are short-circuited when not in use and act as an electrodynamic brake.

25. The optical deflection unit, according to claim 4, wherein an additional electromagnetically activated spring element is used for damping of the movement of the movable frames and which secures the movable frames when not in use.

26. The optical deflection unit, according to claim 1, wherein the electromagnets, functioning as non-contacting, electromagnetic drives, are used for damping of the movement of the movable frame, whereby they are short-circuited when not in use and act as an electrodynamic brake.

22. An optical deflection unit for scanning, ophthalmological measuring, and therapy systems comprising a deflection mirror, oscillatingly movable through non-contacting electromagnetic drives around at least one rotation axis, and which is arranged between at least two bearings in the direction of the at least one rotation axis, a position sensor, and a control unit, the deflection mirror, the position sensor, and the control unit forming a control circuit for minimizing the deviation of the actual positions, detected by the position sensor, from the desired positions of the deflection mirror.