Femtosecond laser processing system with process parameters controls and feedback

• US 9,147,989 B2
• Filed: 12/09/2013
• Issued: 09/29/2015
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Shah, Lawrence, Bovatsek, James M., Arai, Alan Y., Yamamoto, Tadashi, Patel, Rajesh S., Harter, Donald J.
• Primary Examiner(s): NGUYEN, DUNG T
• Application Number:
  US14/100,912
• Publication Number:
  US 20140092927A1
• Time in Patent Office: 659 Days
• Field of Search: 372/6, 372/9, 372/25, 372/29.014
• US Class Current: 1/1
• 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. A system, comprising:

a source of laser pulses, wherein said laser pulses comprise bursts of composite laser pulses, said composite pulses comprising two or more pulses overlapped in time, or spaced very closely in time, at least one of said two or more pulses comprising an ultrashort pulse, said source comprising at least one fiber amplifier;

a controller to control said source; and

a beam manipulator to monitor one or more pulse characteristics of said laser pulses and to generate feedback data for said controller,

wherein said pulse characteristics comprise an output power, a pulse energy, a pulse width, a wavelength, a repetition rate, a polarization, a temporal delay, a temporal phase, a spatial phase, or a combination thereof,

wherein said controller receives signals representative of said one or more pulse characteristics and generates control signals to vary at least one of said pulse characteristics, said controller being networked to at least one computing means via a physical link and/or wireless link.

2. The system of claim 1, wherein at least a portion of said beam manipulator is disposed downstream from said source of pulses, and arranged to manipulate laser pulses directed downstream from said source and toward a material processing beam path for application to target material.

3. The system of claim 1, wherein said source is capable of generating output pulses at a variable repetition rate.

4. The system of claim 1, wherein said source comprises a fiber-based chirped pulse amplification system having a pulse stretcher and a pulse compressor.

5. The system of claim 4, wherein said fiber-based chirped pulse amplification system comprises a pulse compressor comprising a single broadband grating.

6. The system of claim 1, wherein said fiber-based chirped pulse amplification system comprises an adjustable grating compressor to compress optical pulses, said grating compressor operatively connected to said controller to align said grating compressor.

7. The system of claim 1, wherein said fiber-based chirped pulse amplification system comprises an automatically adjustable grating compressor to compress optical pulses, said automatically adjustable grating compressor operatively connected to said controller to control a pulse duration of said ultrashort pulses.

8. The system of claim 7, wherein said chirped pulse amplification system is configured to provide adjustable stretching and compression ratios for control of a pulse width of ultrashort pulses.

9. The system of claim 7, wherein a minimum pulse duration of said ultrashort pulses is maintained via adjustment of said pulse compressor.

10. The system of claim 7, wherein separation between gratings of said adjustable grating compressor is adjustable to minimize an ultrashort pulse duration with adjustment of a pulse repetition rate.

11. The system of claim 1, wherein said beam manipulator comprises an optical gating device that measures the pulse duration of the laser pulses.

12. The system of claim 1, wherein said beam manipulator comprises beam steering optics that control an impingement location of the laser pulses on the target substrate.

13. The system of claim 1, wherein said beam manipulator comprises a telescopic optical device to control the size, shape, divergence or polarization of the laser pulses input into the beam manipulator.

14. The system of claim 1, wherein said controller comprises:

a computing or communicating device.

15. The system of claim 14, wherein said computing or communicating device comprises:

a desktop computer, a laptop computer, a tablet computer, a handheld computer, or a workstation computer.

16. The system of claim 1, and wherein said source generates a burst of multiple pulses, said source further comprising:

a series of chirped gratings disposed prior to said fiber amplifier that reflect laser energy at different wavelengths, and series of chirped gratings disposed after said fiber amplifier to recombine and/or compress pulses of the burst.

17. The system of claim 1, wherein said beam manipulator comprises means for optically converting the fundamental frequency of a percentage of the generated laser pulses to one or more other optical frequencies.

18. A system, comprising:

a fiber-based source of ultrashort laser pulses;

a controller to control said fiber-based source; and

a beam manipulator to monitor one or more pulse characteristics of said laser pulses and to generate feedback data for said controller,

wherein said pulse characteristics comprise an output power, a pulse energy, a pulse width, a wavelength, a repetition rate, a polarization, a temporal delay, a temporal phase, a spatial phase, or a combination thereof,

wherein said fiber-based source, said controller, and said beam manipulator are arranged in a laser-based material processing system for processing of target material, and provides for active control of processing parameters,

wherein at least a portion of said beam manipulator is disposed downstream from said fiber-based source, and said laser processing system is configured such that operation of sub-components therein is individually or cooperatively adjustable.

19. The system of claim 18, wherein said controller is operatively arranged to receive status and diagnostic information from element(s) of the laser processing system.

20. The system of claim 18, wherein said target material comprises a transparent substrate, and said material processing system is configured to fabricate a hole, a channel, or a via in said transparent substrate, to mark said transparent substrate, or weld said transparent substrate.

21. The system of claim 18, wherein said laser processing system comprises a tool monitoring a condition of the target material.

22. The system of claim 21, wherein said tool is configured for spectroscopic analysis of light generated during laser ablation with ultrashort pulses, and wherein a pulse characteristic is modified by said controller based on a result obtained from said spectroscopic analysis.

23. The system of claim 18, wherein said material processing system comprises at least one of an illumination and a microscopic viewing system to examine a target substrate, spectroscopic diagnostics, a range finder and a camera based imaging system.

24. The system of claim 18, wherein said system further comprises a pulse compressor, and said compressor is operatively arranged to compensate for optical dispersion caused by optical component(s) in said laser-based material processing system.

25. The system of claim 18, wherein said laser pulses comprise bursts of composite laser pulses, said composite pulses comprising two or more pulses overlapped in time, or spaced very closely in time, said fiber-based source comprising at least one fiber amplifier.

26. A system, comprising:

one or more laser sources capable of generating laser pulses, including a fiber-based source of ultrashort pulses comprising at least one fiber amplifier, said pulses comprising a first pulse having a pulse width in the femtosecond to picosecond range, and a second pulse having a pulse width in the nanosecond range, said first and second pulses being overlapped in time, or spaced very closely in time, wherein said first and second pulses are generated at a repetition rate from 10 kilohertz to 50 megahertz, and with an output pulse energy range from 100 nanojoules to 100 millijoules;

a controller to control said one or more laser sources; and

a beam manipulator to monitor one or more pulse characteristics of said laser pulses and to generate feedback data for said controller,

wherein said pulse characteristics comprise an output power, a pulse energy, a pulse width, a wavelength, a repetition rate, a polarization, a temporal delay, a temporal phase, a spatial phase, or a combination thereof.

27. The system according to claim 26, wherein said controller receives signals representative of said one or more pulse characteristics and generates control signals to vary at least one of said pulse characteristics, said controller being networked to at least one computing means via a physical link and/or wireless link.

28. The system of according to claim 26, wherein said system is configured in a material processing system for surface marking, sub-surface marking and/or surface texturing of a target.

29. The system of claim 26, wherein said system is configured in material processing system for fabricating holes, channels or vias in a target.

30. The system of claim 26, wherein said laser-based material processing system is configured in a material processing system to weld a material transparent at a wavelength of said fiber-based source, and with high repetition rate femtosecond laser pulses generated at a repetition rate in the range from 10 kHz to 50 MHz so as to allow for accumulation of heat from pulse-to-pulse.