System and method for processing electromagnetic radiation

Patent metadata

Field	Value
Publication number	US-9529244-B2
Application number	US-201214129742-A
Country	US
Kind code	B2
Filing date	Jun 28, 2012
Priority date	Jun 28, 2011
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

The present invention relates to a system and a method for processing electromagnetic radiation. In particular, the present invention relates to conversion of light, such as light ( 28 ) comprising image information ( 34 ), from one wavelength interval to another wavelength interval. More in particular, the present invention relates to wavelength conversion of incident light ( 28 ) by means of optical mixing with a laser beam in a non-linear crystal ( 14 ). The method according to the present invention comprises receiving incoming electromagnetic radiation ( 28 ) and a laser beam ( 12 ) in a non-linear crystal, setting a plurality of phase match conditions within the non-linear crystal ( 14 ), obtaining a plurality of images of the processed electromagnetic radiation ( 30 ), and providing a first combined image ( 42 ) comprising a first part of a first image and comprising a second part of a second image. The wavelength conversion is realized in an intra-cavity arrangement by for example sum-frequency generation between the intra-cavity laser light ( 12 ) and the in-coupled radiation ( 28 ).

First claim

The invention claimed is:

1. A method for processing polychromatic incoming electromagnetic radiation from an object space, the polychromatic incoming electromagnetic radiation comprising radiation in a first wavelength interval, the method comprising:
receiving the polychromatic incoming electromagnetic radiation and a laser beam in a non-linear crystal, wherein interaction between the polychromatic incoming electromagnetic radiation in the first wavelength interval and the laser beam provides processed electromagnetic radiation comprising radiation in a second wavelength interval,
setting a plurality of phase match conditions within the non-linear crystal for the polychromatic incoming electromagnetic radiation propagating in a first direction within the non-linear crystal, the plurality of phase match conditions including a first phase match condition and a second phase match condition,
obtaining a plurality of images of the processed electromagnetic radiation, the plurality of images including a first image obtained during application of the first phase match condition and including a second image obtained during application of the second phase match condition, the first image comprising a first image part corresponding to a first spatial part of the object space, the second image comprising a second image part corresponding to a second spatial part of the object space, and
providing a first combined image comprising the first image part of the first image and comprising the second image part of the second image, wherein the first combined image represents wavelengths of an interval that are narrower than the radiation in the second wavelength interval.

2. The method according to claim 1 , wherein the incoming electromagnetic radiation is polychromatic and wherein the first combined image represents(?) wavelengths of an interval that are narrower than the radiation in the second wavelength interval.

3. The method according to claim 1 , wherein the first part of the first image and the second part of the second image represent radiation of similar wavelength interval.

4. The method according to claim 1 , wherein the setting a plurality of phase match conditions includes adjusting or setting at least one of:
the wavelength of the laser beam,
the rotational position of the non-linear crystal about a rotational axis that is non-parallel with a path of the incoming electromagnetic radiation through the non-linear crystal,
the transverse position of the non-linear crystal in relation to a path of the incoming electromagnetic radiation through the non-linear crystal,
the temperature of the non-linear crystal,
a condition for electro optic tuning of the non-linear crystal, and
application of stress to the non-linear crystal.

5. The method according to claim 1 , wherein the first spatial part of the object space and the second spatial part of the object space represent overlapping or adjacent parts of the object space.

6. The method according to claim 1 , wherein
the plurality of phase match conditions includes a third phase match condition, and
the plurality of images includes a third image obtained during application of the third phase match condition.

7. The method according to claim 6 , wherein
the third image comprising a third image part corresponding to a third spatial part of the object space, and
the first combined image comprises the third part of the third image.

8. The method according to claim 6 , wherein
the second image comprises a first image part corresponding to the first spatial part of the object space,
the third image comprises a second image part corresponding to the second spatial part of the object space, and wherein
the method comprising providing a second combined image comprising the first part of the second image and comprising the second part of the third image.

9. The method according to claim 1 , wherein the laser beam is an intra-cavity laser beam in a first unidirectional ring cavity.

10. The method according to claim 9 , wherein the first cavity is a first unidirectional ring cavity.

11. The method according to claim 1 , wherein the laser beam is a continuous wave laser beam.

12. The method according to claim 1 , wherein the shortest wavelength of the second wavelength interval is shorter than the shortest wavelength of the first wavelength interval.

13. The method according to claim 1 , wherein the non-linear crystal is configured to be quasi phase matched for conversion of the incoming incoherent electromagnetic radiation in the first wavelength interval to the processed electromagnetic radiation in the second wavelength interval.

14. The method according to claim 13 , wherein the non-linear crystal is aperiodically poled.

15. The method according to claim 1 , wherein the incoming electromagnetic radiation is incoherent.

16. The method according to claim 1 , the method comprising filtering of the processed electromagnetic radiation before obtaining the plurality of images of the processed electromagnetic radiation.

17. The method according to claim 16 , wherein the filtering is configured to be tuned.

18. The method according to claim 17 , wherein the filtering comprises use of an etalon.

19. The method according to claim 16 , wherein the incoming electromagnetic radiation is temporally and/or spatially.

20. A system for processing polychromatic incoming electromagnetic radiation from an object space, the polychromatic incoming electromagnetic radiation comprising radiation in a first wavelength interval, the system comprising:
a non-linear crystal being configured for receiving the polychromatic incoming electromagnetic radiation and for receiving a laser beam, such that interaction between the polychromatic incoming electromagnetic radiation within the first wavelength interval and the laser beam provides processed electromagnetic radiation comprising radiation in a second wavelength interval,
a control device being configured for enabling setting a plurality of phase match conditions within the non-linear crystal for the polychromatic incoming electromagnetic radiation propagating in a first direction within the non-linear crystal, the plurality of phase match conditions including a first phase match condition and a second phase match condition,
a detector being configured for obtaining a plurality of images of the processed electromagnetic radiation, the plurality of images including a first image obtained during application of the first phase match condition and including a second image obtained during application of the second phase match condition, the first image comprising a first image part corresponding to a first spatial part of the object space, the second image comprising a second image part corresponding to a second spatial part of the object space, and
a processor being configured for providing a first combined image comprising the first image part of the first image and comprising the second image part of the second image, wherein the first combined image represents wavelengths of an interval that are narrower than the radiation in the second wavelength interval.

21. The system according to claim 20 , wherein the incoming electromagnetic radiation is polychromatic and wherein the first combined image represents? wavelengths of an interval that are narrower than the radiation in the second wavelength interval.

22. The system according to claim 20 , wherein the system comprises a filter configured for filtering

Assignees

• Dam Jeppe Seidelin
• Tidemand-Lichtenberg Peter
• Sørensen Knud Palmelund
• Pedersen Christian
• Univ Danmarks Tekniske

Inventors

• Dam Jeppe Seidelin
• Tidemand-Lichtenberg Peter
• Sørensen Knud Palmelund
• Pedersen Christian

Classifications

• G01S17/89

  for mapping or imaging · CPC title

• G01S7/4811

  common to transmitter and receiver · CPC title

• H01S3/2383

  Parallel arrangements · CPC title

• H01S3/083

  Ring lasers {(fibre ring lasers H01S3/06791)} · CPC title

• G01S7/4915

  Time delay measurement, e.g. operational details for pixel components (signal extraction and conditioning G01S7/493); Phase measurement · CPC title