Laser Material Processing System

• US 20090188901A1
• Filed: 04/09/2007
• Published: 07/30/2009
• Est. Priority Date: 04/10/2006
• Status: Active Grant

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Dantus, Marcos
• Granted Patent: US 9,018,562 B2
• Time in Patent Office: Days
• US Class Current: 219/121.760
• CPC Class Codes: B23K 2103/08 Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/54 Glass
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0665 by beam condensation on the workpiece, e.g. for focusing
• CPC Class Codes: B23K 26/067 Dividing the beam into multiple beams, e.g. multifocusing
• CPC Class Codes: B23K 26/0673 into independently operating sub-beams, e.g. beam multiplexing to provide laser beams for several stations
• CPC Class Codes: B23K 26/0676 into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations
• CPC Class Codes: B23K 26/0853 Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
• CPC Class Codes: B23K 26/348 in combination with arc heating, e.g. TIG [tungsten inert gas], MIG [metal inert gas] or plasma welding laser beam for starting a welding or cutting arc B23K9/067
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/382 by boring
• CPC Class Codes: B23K 26/384 of specially shaped holes
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108

Abstract

A laser material processing system and method are provided. A further aspect of the present invention employs a laser for micromachining. In another aspect of the present invention, the system uses a hollow waveguide. In another aspect of the present invention, a laser beam pulse is given broad bandwidth for workpiece modification.

Claims

1. A laser material processing system comprising:

a laser operable to emit a laser beam pulse;

a shaper operable to shape the pulse;

a hollow waveguide located in the path of the pulse to broaden the bandwidth of the pulse greater than about 20 nm; and

a workpiece micromachined by the pulse.

2. The system of claim 1, wherein the shaper uses multiphoton intrapulse interference phase scan for pulse characterization and compensation in a path of the pulse.

3. The system of claim 1, wherein the waveguide includes an elongated tube made of at least one of:

(a) glass, and (b) quartz; and

the pulse has a duration less than about 500 femtoseconds.

4. The system of claim 1, further comprising a workpiece support automatically moving the workpiece relative to the laser beam pulse, and a programmable controller operably controlling the workpiece support, the laser and the shaper.

5. The system of claim 1, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine the same workpiece.

6. The system of claim 1, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine multiples of the workpiece in multiple machining stations.

7. The system of claim 1, further comprising a tank containing a liquid, the workpiece being entirely submerged in the liquid during micromachining, and the liquid assisting in focusing the laser pulse.

8. The system of claim 1, further comprising a two-dimensional spatial light modulator operably causing the pulse to create a pattern in the workpiece.

9. The system of claim 1, wherein the pulse has a duration of about 100-500 femtoseconds and the workpiece is metal.

10. The system of claim 1, wherein the pulse is transform limited and has a duration of about 10-50 femtoseconds, and the workpiece is a nonmetallic material.

11. The system of claim 1, further comprising:

a programmable controller connected to the shaper;

a detector connected to the controller;

wherein a surface of the workpiece creates second harmonic emission of the laser pulse which is detected by the detector to characterize the laser pulses, such that a SHG crystal is not employed.

12. A laser system comprising:

a laser operable to emit a laser beam pulse;

a shaper operable to shape the pulse;

a hollow waveguide located in the path of the pulse to broaden the bandwidth of the pulse;

a programmable controller connected to the shaper; and

a laser pulse detector connected to the controller;

the controller operably receiving a signal from the detector indicative of distortion of the laser pulse and causing the shaper to vary a characteristic of subsequent pulses passing through the shaper to correct the distortion.

13. The system of claim 12, further comprising micromachining a workpiece with the shaped and bandwidth-broadened laser pulse.

14. The system of claim 12, wherein the waveguide includes an elongated tube made of at least one of:

(a) glass, and (b) quartz; and

the pulse has a duration less than about 500 femtoseconds.

15. The system of claim 12, further comprising a workpiece support automatically moving the workpiece relative to the laser beam pulse, and the controller operably controlling the workpiece support.

16. The system of claim 12, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine the same workpiece.

17. The system of claim 12, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine workpieces in multiple machining stations.

18. The system of claim 12, further comprising a tank containing a liquid, a workpiece being entirely submerged in the liquid during use, and the liquid assisting in focusing the laser pulse.

19. The system of claim 12, further comprising a two-dimensional spatial light modulator operably causing the pulse to create a pattern in the workpiece.

20. The system of claim 12, further comprising a surface of a workpiece operably creating second harmonic emission of the laser pulse which is detected by the detector to monitor the laser performance.

21. A laser material processing system comprising:

a laser operable to emit a laser beam pulse;

a shaper operable to shape the pulse;

a programmable controller connected to the shaper;

the controller operably using multiphoton intrapulse interference phase scan programmed instructions to automatically perform pulse characterization and compensation in the pulse; and

a workpiece micromachined by the pulse.

22. The system of claim 21, further comprising a workpiece support automatically moving the workpiece relative to the laser beam pulse, and a programmable controller operably controlling the workpiece support, the laser and the shaper.

23. The system of claim 21, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine the same workpiece.

24. The system of claim 21, further comprising at least one optic device splitting the laser beam pulse into multiple sub-pulses which simultaneously micromachine multiples of the workpiece in multiple machining stations.

25. The system of claim 21, further comprising a tank containing a liquid, the workpiece being entirely submerged in the liquid during micromachining, and the liquid assisting in focusing the laser pulse.

26. The system of claim 21, wherein the shaper is a two-dimensional spatial light modulator.

27. The system of claim 21, wherein the pulse has a duration of about 100-500 femtoseconds and the workpiece is metal.

28. The system of claim 21, wherein the pulse is transform limited and has a duration of about 10-50 femtoseconds, and the workpiece is a nonmetallic material.

29. The system of claim 21, further comprising:

a detector connected to the controller;

wherein a surface of the workpiece creates second harmonic emission of the laser pulse which is detected by the detector, such that a SHG crystal is not employed.

30-51. -51. (canceled)

52. A laser material processing system comprising:

a laser operably emitting at least one laser beam pulse;

an electrical circuit conducting electrical current and supplying an electrical arc adjacent the pulse; and

a workpiece micromachined by at least the pulse.

53. The system of claim 52, further comprising:

an objective emitting the pulse; and

a conductor located adjacent the pulse emitting the electrical arc to the workpiece.

54. The system of claim 52, further comprising a sensor and a programmable controller, the sensor being substantially located on an opposite side of the workpiece from the objective, the pulse having a duration of less than about 500 femtoseconds, and the controller determining when the pulse has reached a desired position relative to the workpiece by sensing the electrical current.

55. The system of claim 52, further comprising a hollow waveguide located in the path of the pulse to broaden the bandwidth of the pulse greater than about 20 nm.

56. The system of claim 52, further comprising a pulse shaper operably shaping the pulse, and a programmable controller connected to the shaper and using multiphoton intrapulse interference phase scan instructions to cause pulse characterization and compensation in a path of the pulse.

57. The system of claim 52, further comprising an objective focusing the pulse, and an elongated and conductive pin connected to the objective, the pin being substantially concentric with the pulse being emitted from the objective.

58. The system of claim 52, further comprising electrical current associated with the arc will vary due to ionization caused by workpiece ablation from the pulse.

59. The system of claim 52, further comprising a programmable controller operably causing subsequent pulses to have different characteristics based at least in part on a signal associated with the arc.

60. The system of claim 52, wherein the laser pulse operably assists in directing the arc toward the area being machined by the pulse.

61. The system of claim 52, further comprising machining a hole in the workpiece with the pulse.

62. The system of claim 52, wherein the pulse has a duration of no greater than 500 femtoseconds.

63. A micromachining system comprising:

a laser operably emitting a first laser beam pulse;

a workpiece;

a pulse shaper operably shaping the first pulse;

a programmable controller connected to the shaper and operably causing the shaper to vary the pulse shape of one or more subsequent pulses transmitted through the shaper; and

at least one optic member causing multiple focal points on the workpiece for each of the pulses.

64. The system of claim 63, wherein each of the pulses micromachines multiple holes within the same workpiece, and each of the pulses has a duration less than about 500 femtoseconds.

65. The system of claim 63, wherein the optic member includes a two-dimensional SLM varied by the controller.

66. The system of claim 63, further comprising an optical assembly spreading and collimating each of the pulses.

67. The system of claim 63, wherein the controller operably uses multiphoton intrapulse interference phase scan programmed instructions to automatically perform pulse characterization and compensation in the pulses.

68. The system of claim 63, further comprising a hollow waveguide located in the path of the pulses to broaden the bandwidth of the pulses greater than about 20 nm.

69. The system of claim 63, further comprising a workpiece support automatically moving the workpiece relative to the laser pulses, and the programmable controller operably controlling the workpiece support.

70. The system of claim 63, further comprising a tank containing a liquid, the workpiece being entirely submerged in the liquid during micromachining, and the liquid assisting in focusing the laser pulses.

71. The system of claim 63, wherein the at least one optic member is a two-dimensional spatial light modulator.

72-100. -100. (canceled)

101. A method of material processing, the method comprising:

(a) emitting at least one laser pulse having a duration less than about 500 femtoseconds;

(b) correcting spectral phase distortions in the at least one pulse using multi-photon intrapulse interference phase scan, after step (a);

(c) broadening the bandwidth of the at least one pulse to about 10-200 nm;

(d) placing a workpiece in a liquid; and

(e) micromachining the workpiece in the liquid with the at least one pulse.

102. The method of claim 101, further comprising automatically shaping laser pulses based at least in part on sensed characteristics of prior laser pulses.

103. The method of claim 101, further comprising assisting in focusing the laser pulse with the liquid.

104. The method of claim 101, further comprising entirely submerging the workpiece in the liquid during micromachining.

105. The method of claim 101, further comprising broadening the bandwidth with a hollow waveguide.

106. The method of claim 101, further comprising submerging the workpiece in oil and micromachining at least one hole in the workpiece of a diameter no greater than 500 nm.

107. The method of claim 101, further comprising using a datum marking on the workpiece to visually align a laser objective with a desired location on the workpiece prior to micromachining.

108-127. -127. (canceled)

128. A method of material processing, the method comprising:

(a) emitting at least one laser pulse onto a workpiece;

(b) shaping the at least one laser pulse with a two-dimensional spatial light modulator; and

(c) machining the workpiece by the at least one laser pulse.

129. The method of claim 128, further comprising shaping the at least one laser pulse with another pulse shaper at a Fourier plane, based at least in part on sensed characteristics of prior laser pulses.

130. The method of claim 128, further comprising using multiphoton intrapulse interference phase scan to cause pulse characterization and compensation in a path of the pulse.

131. The method of claim 128, further comprising making a polygonal shaped hole in the workpiece with the at least one shaped pulse.

132. The method of claim 128, further comprising using a programmable controller to automatically cause subsequent laser pulses to have different characteristics.