System and method for electrodeless plasma ignition in laser-sustained plasma light source

Patent metadata

Field	Value
Publication number	US-10244613-B2
Application number	US-201615280073-A
Country	US
Kind code	B2
Filing date	Sep 29, 2016
Priority date	Oct 4, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

An illumination source for igniting and sustaining a plasma in a plasma lamp of a laser-sustained plasma (LSP) broadband source includes one or more ignition lasers configured to ignite the plasma within a gas contained within the plasma lamp. The illumination sources also include one or more sustaining lasers configured to sustain the plasma. The illumination sources include a delivery optical fiber, one or more optical elements configured to selectively optically couple an output of the one or more ignition lasers, and an output of the one or more sustaining lasers to the delivery optical fiber.

First claim

What is claimed:

1. An illumination source for electrodeless plasma ignition comprising:
one or more pulsed ignition lasers configured to ignite a plasma within a gas contained within a plasma lamp;
one or more continuous-wave sustaining lasers configured to sustain the plasma;
a delivery optical fiber; and
one or more optical elements configured to selectively optically couple an output of the one or more pulsed ignition lasers and an output of the one or more continuous-wave sustaining lasers to the delivery optical fiber, wherein the output of the one or more ignition lasers is coupled in-line with the output of the one or more continuous-wave sustaining lasers prior to an input of the delivery optical fiber.

2. The illumination source of claim 1 , wherein the one or more continuous-wave sustaining lasers comprise:
one or more diode lasers.

3. The illumination source of claim 1 , wherein the one or more optical elements configured to selectively optically couple an output of the one or more ignition lasers in-line and an output of the one or more continuous-wave sustaining lasers to the delivery optical fiber comprise:
at least one of one or more dichroic mirrors, one or more polarizing combiners, one or more blocking mirrors or one or more flip mirrors.

4. An illumination source for electrodeless plasma ignition comprising:
one or more pulsed ignition lasers configured to ignite a plasma within a gas contained within a plasma lamp;
one or more continuous-wave sustaining lasers configured to sustain the plasma;
a delivery optical fiber, wherein an output of the one or more continuous-wave sustaining lasers is coupled to an input of the delivery fiber;
a process optical fiber; and
a fiber coupler optically coupled to an output of the delivery optical fiber and an input of the process optical fiber, wherein the fiber coupler includes one or more dichroic mirrors configured to selectively optically couple an output of the one or more pulsed ignition lasers and an output of the one or more continuous-wave sustaining lasers, from the delivery optical fiber, to an input of the process optical fiber.

5. The illumination source of claim 4 , wherein the one or more dichroic mirrors of the fiber coupler are configured to couple an output of the delivery optical fiber and the one or more pulsed ignition lasers to an input of the process optical fiber.

6. The illumination source of claim 4 , wherein the output of the one or more pulsed ignition lasers is coupled in-line with the output of the one or more continuous-wave sustaining lasers downstream of an output of the delivery optical fiber.

7. The illumination source of claim 4 , wherein the one or more continuous-wave sustaining lasers comprise:
one or more diode lasers.

8. A plasma broadband source comprising:
a plasma lamp for containing a volume of gas,
one or more pulsed ignition lasers;
one or more continuous-wave sustaining lasers;
a delivery optical fiber;
one or more optical elements configured to selectively optically couple an output of the one or more pulsed ignition lasers and an output of the one or more continuous-wave sustaining lasers to the delivery optical fiber, wherein the output of the one or more ignition lasers is coupled in-line with the output of the one or more continuous-wave sustaining lasers prior to an input of the delivery optical fiber; and
one or more lamp optics configured to direct an output from the delivery optical fiber to the volume of gas within the plasma lamp to ignite and sustain the plasma within the volume of gas in the plasma lamp.

9. The plasma broadband source of claim 8 , wherein the one or more continuous-wave sustaining lasers comprise:
one or more diode lasers.

10. The plasma broadband source of claim 8 , wherein the one or more optical elements configured to selectively optically couple an output of the one or more pulsed ignition lasers and an output of the one or more continuous-wave sustaining lasers to the delivery optical fiber comprise:
at least one of one or more dichroic mirrors, one or more polarizing combiners, one or more blocking mirrors or one or more flip mirrors.

11. The plasma broadband source of claim 10 , wherein the one or more lamp optics are configured to collect at least a portion of broadband radiation emitted by the generated plasma and direct the broadband radiation to one or more additional optical elements.

12. The plasma broadband source of claim 8 , wherein the one or more lamp optics comprise:
a collector element.

13. The plasma broadband source of claim 12 , wherein the collector element comprises:
at least one of an ellipsoidal collector mirror, a parabolic collector mirror or a spherical collector mirror.

14. The plasma broadband source of claim 8 , wherein the one or more lamp optics comprise:
a set of reflector elements configured to direct an output from the delivery optical fiber to the volume of gas within the plasma lamp; and
a set of collector elements configured to collect at least a portion of broadband radiation emitted by the generated plasma and direct the broadband radiation to one or more additional optical elements.

15. The plasma broadband source of claim 8 , wherein the plasma lamp includes a plasma bulb.

16. The plasma broadband source of claim 15 , wherein the plasma bulb has at least one of a substantially cylindrical shape or a substantially spherical shape.

17. The plasma broadband source of claim 15 , wherein the plasma bulb has a substantially cardioid shape.

18. The plasma broadband source of claim 17 , wherein the plasma bulb has a peak disposed on an internal surface of the bulb configured to direct convection within the plasma bulb.

19. The plasma broadband source of claim 8 , wherein the plasma lamp is electrodeless.

20. The plasma broadband source of claim 8 , wherein the gas of the plasma bulb comprises:
at least one of an inert gas, a non-inert gas or a mixture of two or more gases.

21. A plasma broadband source comprising:
a plasma lamp for containing a volume of gas,
one or more pulsed ignition lasers;
one or more continuous-wave sustaining lasers;
a delivery optical fiber, wherein an output of the one or more continuous-wave sustaining lasers is coupled to an input of the delivery fiber;
a process optical fiber;
a fiber coupler optically coupled to an output of the delivery optical fiber and an input of the process optical fiber, wherein the fiber coupler includes one or more dichroic mirrors configured to selectively optically couple an output of the one or more pulsed ignition lasers and an output of the one or more continuous-wave sustaining lasers to an input of the process optical fiber; and
one or more lamp optics configured to direct an output from the process optical fiber to the volume of gas within the plasma lamp to ignite and sustain the plasma within the volume of gas in the plasma lamp.

22. The plasma broadband source of claim 21 , wherein the one or more dichroic mirrors of the fiber coupler are configured to couple an output of the delivery optical fiber and the one or more pulsed ignition lasers to an input of the process optical fiber.

23. The plasma broadband source of claim 21 , wherein the output of the one or more pulsed ignition lasers is coupled in-line with the output of the one or more continuous-wave sustaining lasers downstream of an output of the delivery optical fiber.

24. The plasma broadband sour

Assignees

• Kla Tencor Corp

Inventors

• Chimmalgi Anant
• Brunner Rudolf
• Shchemelinin Anatoly
• Bezel Ilya
• Kim Erik
• Patil Rajeev

Classifications

• H01J61/025

  Associated optical elements · CPC title

• H05G2/003

  the plasma being generated from a material in a liquid or gas state · CPC title

• H01J61/54 Primary

  Igniting arrangements, e.g. promoting ionisation for starting · CPC title

• G02B6/4204

  the coupling comprising intermediate optical elements, e.g. lenses, holograms (encapsulated active devices H01S5/02208) · CPC title

• H05G2/008 Primary

  involving an energy-carrying beam in the process of plasma generation · CPC title