Control system using a phase modulation capable acousto-optic modulator for diverting laser output intensity noise to a first order laser light beam and related methods

Patent metadata

Field	Value
Publication number	US-9958711-B1
Application number	US-201615342372-A
Country	US
Kind code	B1
Filing date	Nov 3, 2016
Priority date	Nov 3, 2016
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

A laser system may include a laser source configured to generate a laser light beam and an acousto-optic modulator (AOM). The AOM may include an acousto-optic medium configured to receive the laser light beam, and a phased array transducer comprising a plurality of electrodes coupled to the acousto-optic medium and configured to cause the acousto-optic medium to output a zero order laser light beam and a first order diffracted laser light beam. The system may further include a beamsplitter downstream from the AOM and configured to split a sampled laser light beam from the zero order laser light beam, a photodetector configured to receive the sampled laser light beam and generate a feedback signal associated therewith, and a radio frequency (RF) driver configured to generate an RF drive signal to the phased array transducer electrodes so that noise is diverted to the first order diffracted laser light beam based upon the feedback signal.

First claim

The invention claimed is:

1. A laser system comprising:
a laser source configured to generate a laser light beam;
an acousto-optic modulator (ACM) comprising
an acousto-optic medium configured to receive the laser light beam, and
a phased array transducer comprising a plurality of electrodes coupled to the acousto-optic medium and configured to cause the acousto-optic medium to output a zero order laser light beam and a first order diffracted laser light beam;

a beamsplitter downstream from the AOM and configured to split a sampled laser light beam from the zero order laser light beam;
a photodetector configured to receive the sampled laser light beam and generate a feedback signal associated therewith; and
a radio frequency (RF) driver configured to generate an RF drive signal to the phased array transducer electrodes so that noise is diverted to the first order diffracted laser light beam based upon the feedback signal.

2. The laser system of claim 1 wherein the RF driver is configured to drive alternating electrodes of the phased array transducer electrodes with different phases.

3. The laser system of claim 2 wherein
the RF driver is configured to drive the alternating electrodes with different phases within a range of 0° to 180°.

4. The laser system of claim 1 wherein an RF power level associated with the RF drive signal has a constant power.

5. The laser system of claim 1 wherein the sampled laser light beam utilizes ≤3% of the light of the zero order laser light beam.

6. The laser system of claim 1 wherein the first order diffracted laser light beam has ≤3% of the light from the laser source.

7. The laser system of claim 1 further comprising an ion trap, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the ion trap.

8. The laser system of claim 1 further comprising a semiconductor workpiece having a photoresist layer, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the photoresist layer.

9. The laser system of claim 1 further comprising a micromachining workpiece, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the micromachining workpiece.

10. A laser system comprising:
a laser source configured to generate a laser light beam;
an acousto-optic modulator (AOM) comprising
an acousto-optic medium configured to receive the laser light beam, and
a phased array transducer comprising a plurality of electrodes coupled to the acousto-optic medium and configured to cause the acousto-optic medium to output a zero order laser light beam and a first order diffracted laser light beam;

a beamsplitter downstream from the AOM and configured to split a sampled laser light beam from the zero order laser light beam;
a photodetector configured to receive the sampled laser light beam and generate a feedback signal associated therewith; and
a radio frequency (RF) driver configured to generate an RF drive signal to the phased array transducer electrodes so that noise is diverted to the first order diffracted laser light beam based upon the feedback signal, the RF driver driving alternating electrodes of the phased array transducer electrodes with different phases, and an RF power level associated with the RF drive signal having a constant power.

11. The laser system of claim 10 wherein the RF driver is configured to drive the alternating electrodes with different phases within a range of 0° to 180°.

12. The laser system of claim 10 wherein the sampled laser light beam utilizes ≤3% of the light of the zero order laser light beam.

13. The laser system of claim 10 wherein the first order diffracted laser light beam has ≤3% of the light from the laser source.

14. The laser system of claim 10 further comprising an ion trap, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the ion trap.

15. The laser system of claim 10 further comprising a semiconductor workpiece having a photoresist layer, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the photoresist layer.

16. The laser system of claim 10 further comprising a micromachining workpiece, and wherein the beamsplitter is configured to direct the zero order laser light beam from the AOM to the micromachining workpiece.

17. A method comprising:
generating a laser light beam using a laser source directed at an acousto-optic medium;
causing the acousto-optic medium to output a zero order laser light beam and a first order diffracted laser light beam using a phased array transducer comprising a plurality of electrodes coupled to the acousto-optic medium;
splitting a sampled laser light beam from the zero order laser light beam using a beamsplitter downstream from the acousto-optic medium;
generating a feedback signal associated with the sampled laser light beam; and
generating a radio frequency (RF) drive signal to the phased array transducer electrodes with an RF driver so that noise is diverted to the first order diffracted laser light beam based upon the feedback signal.

18. The method of claim 17 wherein generating the RF drive signal comprises generating the RF drive signal to drive alternating electrodes of the phased array transducer electrodes with different phases.

19. The method of claim 17 wherein an RF power level associated with the RF drive signal has a constant power.

20. The method of claim 17 wherein the sampled laser light beam utilizes ≤3% of the light of the zero order laser light beam.

21. The method of claim 17 wherein the first order diffracted laser light beam has ≤3% of the light from the laser source.

22. The method of claim 17 wherein splitting the beam further comprises directing the zero order laser light beam to an ion trap.

23. The method of claim 17 wherein splitting the beam further comprises directing the zero order laser light beam to a photoresist layer on a semiconductor workpiece.

24. The method of claim 17 wherein splitting the beam further comprises directing the zero order laser light beam to a micromachining workpiece.

Assignees

• Harris Corp

Inventors

• Morse Randall K
• Wasilousky Peter A
• Burberry Lee M
• Lange Michael R
• Logan Catheryn D
• Bentley Pat O

Classifications

• H10P76/204

  of organic photoresist masks · CPC title

• H10P72/0436

  mainly by radiation · CPC title

• H10P34/42

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• G21K1/00

  Arrangements for handling particles or ionising radiation, e.g. focusing or moderating · CPC title

• H01L21/268

  Electricity · mapped topic