System and method for spectral tuning of broadband light sources

Patent metadata

Field	Value
Publication number	US-10422508-B2
Application number	US-201615339312-A
Country	US
Kind code	B2
Filing date	Oct 31, 2016
Priority date	Mar 28, 2016
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

A tunable spectral filter includes a first tunable dispersive element, a first optical element, a spatial filtering element located at the focal plane, a second optical element, and a second dispersive element. The first tunable dispersive element introduces spectral dispersion to an illumination beam with an adjustable dispersion. The first optical element focuses the illumination beam at a focal plane in which a distribution of a spectrum of the spectrally-dispersed illumination beam at the focal plane is controllable by adjusting the dispersion of the first tunable dispersive element. The spatial filtering element filters the spectrum of the illumination beam based on the distribution of the spectrum of the illumination beam at the focal plane. The second optical element collects the spectrally-dispersed illumination beam transmitted from the spatial filtering element. The second tunable dispersive element removes the dispersion introduced by the first tunable dispersive element from the illumination beam.

First claim

What is claimed:

1. A tunable spectral filter, comprising:
a first tunable dispersive element, wherein a dispersion of the first tunable dispersive element is adjustable, wherein the first tunable dispersive element is configured to introduce spectral dispersion to an illumination beam;
a first optical element, the first optical element configured to receive the illumination beam from the first tunable dispersive element and focus the illumination beam at a focal plane, wherein a spatial distribution of a spectrum of the illumination beam at the focal plane is controllable by adjusting the dispersion of the first tunable dispersive element;
a spatial filtering element located at the focal plane, wherein the spatial filtering element filters a spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam at the focal plane to form a filtered illumination beam having a filtered spectrum;
a second optical element configured to collect the filtered illumination beam from the spatial filtering element; and
a second tunable dispersive element configured to receive the filtered illumination beam from the second optical element, wherein a dispersion of the second tunable dispersive element is configured to correspond to the dispersion of the first tunable dispersive element, wherein the second tunable dispersive element is configured to remove the spectral dispersion introduced by the first tunable dispersive element from the filtered illumination beam.

2. The tunable spectral filter of claim 1 , wherein the first tunable dispersive element is configured to accept a spatially coherent illumination beam.

3. The tunable spectral filter of claim 2 , wherein the spatially coherent illumination beam comprises:
a supercontinuum laser source.

4. The tunable spectral filter of claim 1 , wherein at least one of the first tunable dispersive element or the second tunable dispersive element comprises:
a diffraction grating.

5. The tunable spectral filter of claim 4 , wherein at least one of a pitch or a diffraction efficiency of the diffraction grating is adjustable.

6. The tunable spectral filter of claim 4 , wherein the diffraction grating comprises:
at least one of an acousto-optic deflector or an electro-optic deflector.

7. The tunable spectral filter of claim 1 , wherein the spatial filter includes a filtering segment to block a portion of the spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam on the filtering segment.

8. The tunable spectral filter of claim 7 , wherein adjusting the dispersion of the first tunable dispersive element controls the portion of the spectrum of the illumination beam blocked by the filtering segment to form the filtered illumination beam.

9. The tunable spectral filter of claim 7 , wherein the filtering segment comprises:
at least one of a low-pass filter or a high-pass filter.

10. The tunable spectral filter of claim 1 , wherein the filtering element comprises:
an aperture to pass a portion of the spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam on the aperture to form the filtered illumination beam.

11. The tunable spectral filter of claim 10 , wherein the aperture comprises:
a bandpass filter.

12. The tunable spectral filter of claim 10 , wherein the aperture includes a first filtering segment and a second filtering segment separated by a width of the aperture, wherein the first filtering segment is configured to block a first portion of the spectrum of the illumination beam, wherein the second filtering segment is configured to block a second portion of the spectrum of the illumination beam, wherein a third portion of the spectrum of the illumination beam propagates through the aperture as the filtered illumination beam and is collected by the second optical element.

13. The tunable spectral filter of claim 12 , wherein adjusting the dispersion of the first tunable dispersive element controls a center wavelength of the filtered illumination beam.

14. The tunable spectral filter of claim 10 , wherein the width of the aperture is adjustable.

15. The tunable spectral filter of claim 14 , wherein adjusting the width of the aperture controls a bandwidth of the filtered illumination beam.

16. The tunable spectral filter of claim 1 , wherein the filtering element comprises:
at least one of a transmissive filtering element or a reflective filtering element.

17. The tunable spectral filter of claim 1 , wherein the filtering element comprises:
a pixelated filtering element.

18. The tunable spectral filter of claim 17 , wherein the pixelated filtering element comprises:
at least one of a spatial-light modulator, a micro-mirror array, or a deformable mirror.

19. The tunable spectral filter of claim 1 , wherein the filtering element comprises:
one or more apodizing elements.

20. The tunable spectral filter of claim 1 , wherein the first optical element and the second optical element comprise:
an afocal optical relay.

21. A tunable spectral filter, comprising:
a first tunable dispersive element, wherein a dispersion of the first tunable dispersive element is adjustable, wherein the first tunable dispersive element is configured to introduce spectral dispersion to an illumination beam;
a first optical element, the first optical element configured to receive the illumination beam from the first tunable dispersive element and focus the illumination beam at a first focal plane, wherein a spatial distribution of a spectrum of the illumination beam at the first focal plane is controllable by adjusting the dispersion of the first tunable dispersive element;
a first filtering segment located at the first focal plane, wherein the first filtering segment filters a spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam at the first focal plane;
a second optical element configured to collect the illumination beam from the first filtering segment;
a beam steering element configured to receive the illumination beam from the second optical element and adjustably modify the trajectory of the illumination beam;
a third optical element, the third optical element configured to receive the illumination beam from the beam steering element and focus the illumination beam at a second focal plane, wherein a spatial distribution of a spectrum of the illumination beam at the second focal plane is controllable by adjusting the beam steering element;
a second filtering segment located at the first focal plane, wherein the second filtering segment filters a spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam at the second focal plane;
a fourth optical element configured to collect the illumination beam from the second filtering segment; and
a second tunable dispersive element configured to receive the illumination beam from the fourth optical element, wherein a dispersion of the second tunable dispersive element is configured to correspond to the dispersion of the first tunable dispersive element, wherein the second tunable dispersive element is configured to remove the spectral dispersion introduced by the first tunable dispersive element from the illumination beam.

22. The tunable spectral filter of claim 21 , wherein the beam steering element comprises:
a mirror secured to at least one of a r

Assignees

• Kla Tencor Corp

Inventors

• Hill Andrew V
• Manassen Amnon
• Bachar Ohad

Classifications

• G01J3/10

  Arrangements of light sources specially adapted for spectrometry or colorimetry · CPC title

• G01J3/0229

  using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters · CPC title

• G02B5/22

  Absorbing filters {(G02B5/201 - G02B5/208 take precedence)} · CPC title

• G02F1/33

  Acousto-optical deflection devices {(circuit or control arrangements therefor G02F1/113)} · CPC title

• G02B26/0825

  the reflecting element being a flexible sheet or membrane, e.g. for varying the focus (flexible mirrors for cosmetic use A45D42/24) · CPC title