Apparatus and method of shaping a laser beam profile

• US 8,277,060 B2
• Filed: 01/26/2009
• Issued: 10/02/2012
• Est. Priority Date: 01/26/2009
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Cook, Lacy G.
• Primary Examiner(s): Doak, Jennifer L.
• Application Number:
  US12/359,645
• Publication Number:
  US 20100188762A1
• Time in Patent Office: 1,345 Days
• Field of Search: 359/29, 359/32, 359850-861, 356/4.01, 356/432, 356/435
• US Class Current: 359/850
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat

Abstract

Various embodiments provide an apparatus and method for shaping a laser beam profile in which the apparatus includes a reformatting optical system configured to reformat a laser beam having a Gaussian intensity profile into a radiation beam having a top hat intensity profile; and a Fourier transforming optical system configured to transform the radiation beam having the top hat intensity profile into a radiation beam having a Bessel or sinc function intensity profile.

Claims

1. An apparatus for shaping a laser beam profile, comprising:

a reformatting optical system configured to reformat a laser beam having a Gaussian intensity profile into a radiation beam having a top hat intensity profile; and

an optical system configured to Fourier transform the radiation beam having the top hat intensity profile into a radiation beam having a Bessel or sinc function intensity profile, the optical system including a first mirror, a second mirror and a third mirror, the first mirror configured to receive the radiation beam having the top hat intensity profile from the reformatting optical system and reflect the radiation beam towards the second mirror, the second mirror configured to reflect the radiation beam received from the first mirror towards the third mirror, and the third mirror is configured to direct the radiation beam received from the second mirror towards an output of the Fourier transforming optical system;

wherein the first mirror and the second mirror form a high telephoto ratio Cassegrain optical system, in which the physical length between the first mirror and the second mirror is reduced by a factor of at least 20 as compared to a conventional f-f Fourier transform configuration.

2. The apparatus of claim 1, wherein the optical system further comprises:

a beam expander configured to reshape the radiation beam having the Bessel or sinc function intensity profile into a radiation beam having an expanded Bessel or sinc function intensity profile.

3. The apparatus of claim 2, wherein the beam expander is further configured to scale and to truncate the Bessel or sinc function intensity profile into an expanded Bessel or sinc function intensity profile.

4. The apparatus of claim 1, wherein the third mirror is a positive power field mirror that achieves a telecentric condition.

5. The apparatus of claim 1, wherein the optical system configured to Fourier transform the radiation beam is telecentric.

6. The apparatus of claim 1, wherein the radiation beam having the Bessel or sinc function intensity profile is input into a LIDAR transmitter.

7. The apparatus of claim 6, wherein a radiation beam output by the LIDAR transmitter has a top hat intensity profile at far-field.

8. The apparatus of claim 1, wherein the first mirror and the third mirror are included in a single mirror.

9. A method of shaping a laser beam profile, comprising:

reformatting a laser beam having a Gaussian intensity profile into a radiation beam having a top hat intensity profile; and

transforming the radiation beam having the top hat intensity profile into a radiation beam having a Bessel or sinc function intensity profile by using an optical system including a first mirror and a second mirror, wherein a physical length between the first mirror and the second mirror is reduced by a factor of at least 20 as compared to a conventional f-f Fourier transform configuration.

10. The method of claim 9, wherein transforming the radiation beam having the top hat intensity profile into the radiation beam having the Bessel intensity profile includes:

reshaping the radiation beam having the Bessel or sinc function intensity profile into a radiation beam having an expanded Bessel or sinc function intensity profile.

11. The method of claim 10, wherein reshaping the radiation beam comprises scaling and truncating the Bessel or sinc function intensity profile into the expanded Bessel or sinc function intensity profile.

12. The method of claim 9, further comprising inputting the radiation beam having the Bessel or sinc function intensity profile into a LIDAR transmitter at near-field.

13. The apparatus of claim 12, further comprising outputting, by the LIDAR transmitter, a radiation beam having a top hat intensity profile.

14. An apparatus for shaping a laser beam profile, comprising:

a reformatting optical system configured to reformat a laser beam having a Gaussian intensity profile into a radiation beam having a top hat intensity profile; and

an optical system configured to Fourier transform the radiation beam having the top hat intensity profile into a radiation beam having a Bessel or sinc function intensity profile, the optical system comprising a first mirror and a second mirror, the first mirror configured to receive the radiation beam having the top hat intensity profile from the reformatting optical system and reflect the radiation beam towards the second mirror, and the second mirror configured to reflect the radiation beam received from the first mirror back towards the first mirror; and

wherein the first mirror is further configured to direct the radiation beam received from the second mirror towards an output of the optical system.

15. The apparatus of claim 14, wherein the optical system is further configured to reshape the radiation beam having the Bessel or sinc function intensity profile into a radiation beam having an expanded Bessel or sinc function intensity profile.

16. The apparatus of claim 15, wherein the optical system is further configured to scale and to truncate the Bessel or sinc function intensity profile into the expanded Bessel or sinc function intensity profile.

17. The apparatus of claim 14, wherein the optical system configured to Fourier transform the radiation beam is telecentric.

18. The apparatus of claim 14, wherein a physical length between the first mirror and the second mirror is reduced by a factor of at least 20 as compared to a conventional f-f Fourier transform configuration.

19. The apparatus of claim 14, wherein the radiation beam having the Bessel or sinc function intensity profile is input into a LIDAR transmitter.

20. The apparatus of claim 19, wherein a radiation beam output by the LIDAR transmitter has a top hat intensity profile at far-field.