Femtosecond laser processing system with process parameters, controls and feedback

• US 7,486,705 B2
• Filed: 03/31/2004
• Issued: 02/03/2009
• Est. Priority Date: 03/31/2004
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Bovatsek, James M, Arai, Alan Y, Patel, Rajesh S., Yamamoto, Tadashi, Harter, Donald J., Shah, Lawrence
• Primary Examiner(s): Nguyen; Dung T
• Application Number:
  US10/813,269
• Publication Number:
  US 20050226287A1
• Time in Patent Office: 1,770 Days
• Field of Search: 327/25
• US Class Current: 372/25
• CPC Class Codes: G01J 11/00 Measuring the characteristics of individual optical pulses or of optical pulse trains
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• 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
• CPC Class Codes: H01S 3/0064 Anti-reflection devices, e.g. optical isolaters absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955
• CPC Class Codes: H01S 3/0078 Frequency filtering
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/10023 by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/10038 Amplitude control
• CPC Class Codes: H01S 3/10061 Polarization control
• CPC Class Codes: H01S 3/102 by controlling the active medium, e.g. by controlling the processes or apparatus for excitation H01S3/13 takes precedence
• CPC Class Codes: H01S 3/1024 for pulse generation
• CPC Class Codes: H01S 3/108 using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering mode locking using a non-linear element H01S3/1112
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/1618 ytterbium

Abstract

A femtosecond laser based laser processing system having a femtosecond laser, frequency conversion optics, beam manipulation optics, target motion control, processing chamber, diagnostic systems and system control modules. The femtosecond laser based laser processing system allows for the utilization of the unique heat control in micromachining, and the system has greater output beam stability, continuously variable repetition rate and unique temporal beam shaping capabilities.

Claims

1. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring the pulsewidth characteristics of the pulses comprising the composite pulse bursts and generating feedback data for the control means for pulsewidth control, the beam manipulating means comprising;

a telescopic optical device to control the size, shape, divergence or polarization of the laser pulses input into the beam manipulation means, and steering optics that control an impingement location of the laser pulses on the target substrate.

2. An apparatus as claimed in claim 1, wherein the laser means comprises a fiber amplifier.

3. An apparatus as claimed in claim 2, wherein the laser means further comprise at least one stretcher grating and at least one compressor.

4. The apparatus as claimed in claim 1, wherein the beam manipulation means comprise an optical gating device that measures the pulse duration of the laser pulses.

5. The apparatus as claimed in claim 4, wherein the beam manipulation means further comprise:

a power meter that measures the power of the laser pulses output from the laser means; and

a photodiode that measures a repetition rate of the laser pulses.

6. The apparatus as claimed in claim 1, wherein the beam manipulation means comprise means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies.

7. The apparatus as claimed in claim 6, the means for converting an optical frequency comprising at least one optical member that converts a portion of the fundamental of the laser pulses into at least one higher order harmonic signal.

8. The apparatus as claimed in claim 7, wherein the optical member device comprises at least one non-linear crystal device with a controller that controls the orientation of the at least one non-linear crystal with respect to the input laser pulses.

9. The apparatus as claimed in claim 6, wherein the means for converting an optical frequency further comprise a spectrometer that measures predetermined parameters of pulses output from the non-linear crystal device and generates feedback for the control means.

10. The apparatus as claimed in claim 1, the apparatus further comprising a beam profiler that monitors characteristics of laser pulses and generates feedback for the control means.

11. An end use device for modifying the refractive index of a target substrate, wherein the end device at least comprises an apparatus according to claim 1.

12. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 1.

13. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 1.

14. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 1.

15. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 1.

16. The apparatus as claimed in claim 1, wherein said laser means comprises a pulse source and a modulator disposed between said source and said amplifier.

17. The apparatus as claimed in claim 16, wherein said source produces pulse widths in the range of femtoseconds to picoseconds.

18. The apparatus as claimed in claim 1, wherein said composite pulses within said burst comprise at least one of time separation, a different pulse width, a different peak power, a different wavelength, and a different polarization.

19. The apparatus as claimed in claim 1, wherein said beam manipulation means produces a beam at a fundamental frequency, at least one harmonic beam at a multiple of said fundamental frequency, and is configured to transmit information for diagnostics from said beam manipulation means to said control means.

20. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring a variable repetition rate of the composite pulse bursts and generating feedback data for the control means for the variable repetition rate, the beam manipulating means comprising;

a telescopic optical device to control the size, shape, divergence or polarization of the laser pulses input into the beam manipulation means, and steering optics that control an impingement location of the laser pulses on the target substrate.

21. An apparatus as claimed in claim 20, wherein the laser means comprises a fiber amplifier.

22. An apparatus as claimed in claim 21, wherein the laser means further comprise at least one stretcher grating and at least one compressor.

23. The apparatus as claimed in claim 20, wherein the beam manipulation means comprise a photodiode that measures a repetition rate of the laser pulses.

24. The apparatus as claimed in claim 23, wherein the beam manipulation means comprise:

a power meter that measures the power of the laser pulses output from the laser means; and

an optical gating device that measures the pulse duration of the laser pulses.

25. The apparatus as claimed in claim 20, wherein the beam manipulation means comprise means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies.

26. The apparatus as claimed in claim 25, the means for converting an optical frequency comprising at least one optical member that converts a portion of the fundamental of the laser pulses into at least one higher order harmonic signal.

27. The apparatus as claimed in claim 26, wherein the optical member device comprises at least one non-linear crystal device with a controller that controls the orientation of the at least one non-linear crystal with respect to the input laser pulses.

28. The apparatus as claimed in claim 25, wherein the means for converting an optical frequency further comprise a spectrometer that measures predetermined parameters of pulses output from the non-linear crystal device and generates feedback for the control means.

29. The apparatus as claimed in claim 20, the apparatus further comprising a beam profiler that monitors characteristics of laser pulses and generates feedback for the control means.

30. An end use device for modifying the refractive index of a target substrate, wherein the end device at least comprises an apparatus according to claim 20.

31. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 20.

32. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 20.

33. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 20.

34. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 20.

35. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring the pulsewidth characteristics of the pulses comprising the composite pulse bursts and generating feedback data for the control means for pulsewidth control, the beam manipulation means comprising means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies, the means for converting an optical frequency comprising at least one optical member that converts a portion of the fundamental of the laser pulses into at least one higher order harmonic signal, the at least one optical member device comprising at least one non-linear crystal device with a controller that controls the orientation of the at least one non-linear crystal with respect to the input laser pulses.

36. An end use device for modifying the refractive index of a target substrate, wherein the end device at least comprises an apparatus according to claim 35.

37. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 35.

38. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 35.

39. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 35.

40. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 35.

41. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring the pulsewidth characteristics of the pulses comprising the composite pulse bursts and generating feedback data for the control means for pulsewidth control, the beam manipulation means comprising means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies, the means for converting an optical frequency further comprising a spectrometer that measures predetermined parameters of pulses output from the non-linear crystal device and generates feedback for the control means.

42. An end use device for modifying the refractive index of a target substrate, wherein the end device at least comprises an apparatus according to claim 41.

43. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 41.

44. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 41.

45. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 41.

46. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 41.

47. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring a variable repetition rate of the composite pulse bursts and generating feedback data for the control means for the variable repetition rate, the beam manipulation means comprising means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies, the means for converting an optical frequency comprising at least one optical member that converts a portion of the fundamental of the laser pulses into at least one higher order harmonic signal, the at least one optical member device comprising at least one non-linear crystal device with a controller that controls the orientation of the at least one non-linear crystal with respect to the input laser pulses.

48. An end use device for modifying the refractive index of a target substrate, wherein the end device at least comprises an apparatus according to claim 47.

49. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 47.

50. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 47.

51. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 47.

52. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 47.

53. An apparatus for generating optical pulses, wherein each pulse may have individualized characteristics, the apparatus comprising:

laser means, for generating bursts of composite pulses, and for amplifying said composite pulses in a same fiber amplifier gain medium, wherein said laser means is configured so that each of said pulses are incident on said same fiber laser gain medium and emitted from the same fiber gain medium along a common optical path;

control means that controls the laser means; and

beam manipulation means for monitoring a variable repetition rate of the composite pulse bursts and generating feedback data for the control means for the variable repetition rate, the beam manipulation means comprising means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies, the means for converting an optical frequency further comprising a spectrometer that measures predetermined parameters of pulses output from the non-linear crystal device and generates feedback for the control means.

54. An end use device for modifying the refractive index of a target substrate, wherein the end use device at least comprises an apparatus according to claim 53.

55. An end use device for surface marking, sub-surface marking and surface texturing of a target substrate, wherein the end device at least comprises an apparatus according to claim 53.

56. An end use device for fabricating holes, channels or vias in a target substrate, wherein the end device at least comprises an apparatus according to claim 53.

57. An end use device for the deposition or removal of thin layers of material on a target substrate, wherein the end device comprises an apparatus according to claim 53.

58. An end use device for the joining, welding or fusing of transparent materials, wherein the end device comprises an apparatus according to claim 53.