Photonic clock stabilized laser comb processing

• US 8,358,671 B2
• Filed: 07/19/2011
• Issued: 01/22/2013
• Est. Priority Date: 03/31/2008
• Status: Expired due to Fees

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Inventors: Baird, Brian W., Bruland, Kelly J., Vandergiessen, Clint R., Unrath, Mark A., Nilsen, Brady, Swaringen, Steve
• Primary Examiner(s): Heinrich, Samuel M
• Application Number:
  US13/186,323
• Publication Number:
  US 20110272388A1
• Time in Patent Office: 553 Days
• Field of Search: 2191216-12172, 219/121.78, 219/121.79, 219/121.82, 219/121.83, 219/121.85, 438128-132, 438/795, 372/25, 372/29.02, 372/30, 372/31
• US Class Current: 372/25
• CPC Class Codes: B23K 26/042 Automatically aligning the laser beam
• CPC Class Codes: B23K 26/0622 by shaping pulses
• 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: H01S 3/0007 Applications not otherwise provided for working metals or other materials by laser beam B23K26/00; using photons to produce a reactive propulsive thrust F03H3/00; optical recording of measured values in general G01D15/14; optics in general G02B; holographic processes or apparatus G03H; optical marking or sensing of data record carriers G06K7/10 - G06K7/14, G06K15/12; injection heating of plasma by laser H05H1/22; acceleration of neutral particles by electromagnetic wave pressure H05H3/04

Abstract

Processing a workpiece with a laser includes generating laser pulses at a first pulse repetition frequency. The first pulse repetition frequency provides reference timing for coordination of a beam positioning system and one or more cooperating beam position compensation elements to align beam delivery coordinates relative to the workpiece. The method also includes, at a second pulse repetition frequency that is lower than the first pulse repetition frequency, selectively amplifying a subset of the laser pulses. The selection of the laser pulses included in the subset is based on the first pulse repetition frequency and position data received from the beam positioning system. The method further includes adjusting the beam delivery coordinates using the one or more cooperating beam position compensation elements so as to direct the amplified laser pulses to selected targets on the workpiece.

Claims

1. A method for processing a workpiece with a laser, the method comprising:

generating laser pulses at a first pulse repetition frequency; and

at a second pulse repetition frequency that is lower than the first pulse repetition frequency, selectively amplifying a subset of the laser pulses, wherein selection of the laser pulses included in the subset is based on the first pulse repetition frequency and position data received from a beam positioning system, and wherein the second pulse repetition frequency is selected such that the first pulse repetition frequency is an integer multiple “

n”

of the second pulse repetition frequency; and

offsetting an interpulse time between a first amplified pulse in the subset and a second amplified pulse in the subset by an integer multiple k of the photonic oscillator interpulse time based on a selected amount of beam delivery coordinate adjustment relative to the workpiece.

2. The method of claim 1, wherein the first pulse repetition frequency is configured to provide reference timing for coordination of the beam positioning system and one or more cooperating beam position compensation elements configured to align beam delivery coordinates relative to the workpiece.

3. The method of claim 2, wherein the method further comprises adjusting the beam delivery coordinates using the one or more cooperating beam position compensation elements so as to direct the amplified laser pulses to selected targets on the workpiece.

4. The method of claim 1, further comprising:

measuring a position of the beam positioning system;

comparing the measured position to an expected position; and

providing the comparison as a position compensation signal.

5. The method of claim 4, wherein adjusting the beam delivery coordinates comprises adjusting at least one of an acousto-optic deflector and a fast steering mirror based on the position compensation signal.

6. The method of claim 4 wherein adjusting the beam delivery coordinates comprises adjusting at least one of an electro-optic deflector and a fast steering mirror based on the position compensation signal.

7. The method of claim 1, further comprising blocking the second amplified pulse from reaching the workpiece.

8. The method of claim 1, wherein adjusting the beam delivery coordinates comprises adjusting at least one of an acousto-optic deflector, an electro-optic modulator, a fast steering mirror, and an interpulse time between a first amplified pulse in the subset and a second amplified pulse in the subset by an integer multiple k of the photonic oscillator interpulse time.

9. A system for processing a workpiece with a beam of laser pulses, the system comprising a pulsed laser source comprising:

a photonic oscillator configured to emit laser pulses at a first pulse repetition frequency;

a first optical modulator to select, at a second pulse repetition frequency that is lower than the first pulse repetition frequency, a subset of the laser pulses for amplification, wherein the selection of the laser pulses included in the subset is based on the first pulse repetition frequency and position data relating to an alignment of a beam positioning system; and

one or more cooperating beam position compensation elements comprising a laser comb indexing module configured to;

select the second pulse repetition frequency such that the first pulse repetition frequency is an integer multiple n of the second pulse repetition frequency; and

offset an interpulse time between a first amplified pulse in the subset and a second amplified pulse in the subset by an integer multiple k of the photonic oscillator interpulse time based on the amount of beam delivery coordinate adjustment.

10. The system of claim 9, wherein the system further comprises the beam positioning system, the beam positioning system being configured to align beam delivery coordinates relative to the workpiece and generate the position data.

11. The system of claim 10, wherein the one or more beam position compensation elements are configured to adjust the alignment of the beam delivery coordinates based on the position data.

12. The system of claim 9, wherein the first pulse repetition frequency is configured to provide reference timing for coordination of a beam positioning system and one or more cooperating beam position compensation elements configured to align beam delivery coordinates relative to the workpiece.

13. The system of claim 9, wherein the pulsed laser source further comprises a diode-pumped mode-locked master oscillator power amplifier.

14. The system of claim 9, wherein the pulsed laser source further comprises a diode-pumped mode-locked master oscillator regenerative amplifier.

15. The system of claim 9, wherein the pulsed laser source further comprises a tandem photonic amplifier.

16. The system of claim 15, wherein the tandem photonic amplifier comprises a diode-pumped ultrafast fiber master oscillator.

17. The system of claim 9, wherein the photonic oscillator comprises an internal clock configured to provide the reference timing signal at the first pulse repetition frequency used to determine which pulses to select for amplification and to adjust one or more cooperating beam positioning compensation elements.

18. The system of claim 11, wherein the one or more cooperating beam position compensation elements comprise at least one of an acousto-optic deflector, an electro-optic deflector, and a fast-steering mirror.

19. The system of claim 9, further comprising a second optical modulator to block the second amplified pulse from reaching the workpiece.

20. A system for processing a workpiece with a beam of laser pulses, the system comprising:

means for generating laser pulses at a first pulse repetition frequency;

a first pulse selection means to select, at a second pulse repetition frequency that is lower than the first pulse repetition frequency, a subset of the laser pulses for amplification

means for selecting the second pulse repetition frequency such that the first pulse repetition frequency is an integer multiple n of the second pulse repetition frequency; and

means for offsetting an interpulse time between a first amplified pulse in the subset and a second amplified pulse in the subset by an integer multiple k of the photonic oscillator interpulse time based on an amount of beam delivery coordinate adjustment.

21. The system of claim 20, wherein the first pulse repetition frequency is configured to provide a reference timing signal for coordination of a beam positioning system and one or more cooperating beam position compensation elements for alignment of beam delivery coordinates relative to the workpiece.

22. The system of claim 20, further comprising a second pulse selection means to block the second pulse from reaching the workpiece.

23. The system of claim 22, wherein at least one of the first pulse selection means and the second pulse selection means is selected from the group comprising an acousto-optic modulator and an electro-optic modulator.