Zonal lenslet array

• US 20060078015A1
• Filed: 10/07/2004
• Published: 04/13/2006
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Franck, Jerome B.
• Granted Patent: US 7,619,811 B2
• Time in Patent Office: Days
• US Class Current: 372/30
• CPC Class Codes: G01J 1/0414 using plane or convex mirrors, parallel phase plates, or plane beam-splitters
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• CPC Class Codes: H01S 3/1086 using scattering effects, e.g. Raman or Brillouin effect

Abstract

The invention includes a master lens, which initially focuses a laser pulse, and then the pulse passes through a zonal lenslet array, which uses different lenslet elements that provide for predetermined focal lengths so as to establish a three or two dimensional, predetermined dispersion of foci of the laser pulse. The zonal lenslet array of the present invention may be thought of as a variant of a Shack-Hartman wave front sensor, but used for an entirely different application.

Claims

1. A laser pulse shaping device comprising:

a laser source producing a laser pulse; and

a zonal lenslet array, which is comprised of different lenslet elements that provide for different focal lengths so as to establish individually predetermined focal lengths of the laser pulse.

2. The laser pulse shaping device of claim 1 wherein the zonal lenslet array has its lenslets configured such that the focal lengths of the lenslet elements lengthen concentrically outward from a midpoint.

3. The laser pulse shaping device of claim 2 wherein the zonal lenslet array has plurality concentric rings of lenslet elements each ring of lenslet elements having a focal length that gets shorter than the next.

4. The laser pulse shaping device of claim 1 wherein the zonal lenslet array has its lenslets configured such that the focal lengths of the lenslets form a three dimensional focal field having a predetermined configuration.

5. The laser pulse shaping device of claim 1 wherein the zonal lenslet array has its lenslets configured such that the focal lengths of the lenslet elements form a two dimensional focal field having a predetermined configuration.

6. The laser pulse shaping device of claim 1 wherein the zonal lenslet array is formed as a three dimensional array having predetermined zones compromising the zonal lenslet array.

7. The laser pulse shaping device of claim 6 wherein the zonal lenslet array is cylindrical such that the zones of the array are uniform in the x-direction and changing in the y direction.

8. A laser pulse shaping device useful for shaping a laser input signal into stimulated Brillouin scattering (SBS) cell compromising:

a first lens which initially focuses an input laser pulse;

a means through which to pass the focused input laser pulse;

a master lens which refocuses the focused input laser pulse; and

a zonal lenslet array, which is comprised of different lenslets that provide for different focal lengths so as to establish individually predetermined focal lengths as the input laser signal is focused into the SBS cell.

9. The laser pulse shaping device of claim 8 wherein the zonal lenslet array has its lenslets configured such that the focal lengths of the lenslets lengthen concentrically outward from a midpoint.

10. The laser pulse shaping device of claim 9 wherein the zonal lenslet array has plurality concentric rings of lenslets each ring of lenslets having a focal length that gets shorter than the next.

11. The laser pulse shaping device of claim 8 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslets form a conical configuration of foci.

12. A method to focus a laser input signal through a matched filter cell into stimulated Brillouin scattering (SBS) cell compromising the steps of:

providing for a master lens which initially focuses an input laser pulse; and

providing for a zonal lenslet array, which is comprised of different lenslet elements that provide for different focal lengths so as to establish individually predetermined focal lengths as the input laser signal is focused into the SBS cell.

13. The method of claim 12 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslets lengthen concentrically outward from a midpoint.

14. The method of claim 13 wherein the zonal lenslet array has plurality concentric rings of lenslets each ring of lenslets having a focal length that gets shorter than the next.

15. The method of claim 12 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslet elements form a conical configuration of foci.

16. The laser pulse shaping device of claim 12 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslets form a three dimensional focal field having a predetermined configuration.

17. The laser pulse shaping device of claim 12 wherein the zonal lenslet array has its lenslets configured such that the focal lengths of the lenslets form a two dimensional focal field having a predetermined configuration.

18. The laser pulse shaping device of claim 12 wherein the zonal lenslet array is formed as a three dimensional array having predetermined zones compromising the zonal lenslet array.

19. The laser pulse shaping device of claim 18 wherein the zonal lenslet array is cylindrical such that the zones of the array are uniform in the x-direction and changing in the y direction.

20. A method to focus a laser input signal through a matched filter cell into stimulated Brillouin scattering (SBS) cell compromising the steps of:

providing for a first lens to focus an input laser pulse;

providing a means through to pass the focused input laser pulse;

providing for a master lens to refocuses the focused input laser pulse; and

providing for a zonal lenslet array, which is comprised of different lenslet elements that provide for different focal lengths so as to establish individually predetermined focal lengths as the input laser signal is focused into the SBS cell.

21. The method of claim 20 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslets lengthen concentrically outward from a midpoint.

22. The method of claim 21 wherein the zonal lenslet array has plurality concentric rings of lenslet elements each ring of lenslets having a focal length that gets shorter than the next.

23. The method of claim 20 wherein the zonal lenslet array has its lenslet elements configured such that the focal lengths of the lenslets form a conical configuration of foci which mirrors a Gaussian profile that is established by the input laser pulse.