Photonic Doppler velocimetry lens array probe incorporating stereo imaging

• US 9,121,861 B2
• Filed: 03/14/2014
• Issued: 09/01/2015
• Est. Priority Date: 03/15/2013
• Status: Expired due to Fees

• Current Assignee: National Security Technologies LLC
• Original Assignee: National Security Technologies LLC
• Inventors: Malone, Robert M., Kaufman, Morris I.
• Primary Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US14/214,234
• Publication Number:
  US 20140347651A1
• Time in Patent Office: 536 Days
• US Class Current: 1/1
• CPC Class Codes: G01J 7/00 Measuring velocity of light
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/4917 superposing optical signals in a photodetector, e.g. optical heterodyne detection
• CPC Class Codes: G02B 6/322 and having centering means being part of the lens for the self-positioning of the lightguide at the focal point, e.g. holes, wells, indents, nibs
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence

Abstract

A probe including a multiple lens array is disclosed to measure velocity distribution of a moving surface along many lines of sight. Laser light, directed to the moving surface is reflected back from the surface and is Doppler shifted, collected into the array, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to the multiple lens array. Numerous fibers in a fiber array project numerous rays to establish many measurement points at numerous different locations. One or more lens groups may be replaced with imaging lenses so a stereo image of the moving surface can be recorded. Imaging a portion of the surface during initial travel can determine whether the surface is breaking up.

Claims

1. A photonic Doppler velocimetry probe comprising

a housing defining an interior space between a first end and a second end;

one or more optic signal conductors entering the housing through the second end and terminating within the interior space of the housing, the one or more optic signal conductors configured to provide one or more optic signals to one or more lenses in the probe;

a ferrule, located within the housing, having one or more passages configured to receive and secure at least one of the one or more optic signal conductors to the ferrule;

an first lens adjacent the ferrule to receive the optic signal, the optic signal traveling in a first direction;

one or more additional lenses adjacent the first lens configured to direct the optic signal;

a prism, mounted at the first end of the probe, the prism configured to receive the optic signal from the one or more additional lenses and reflect the optic signal outward in a second direction, the second direction being different than the first direction.

2. The probe of claim 1 wherein the one or more optic signal conductors are one or more optic fibers.

3. The probe of claim 2 wherein the one or more additional lenses comprises an aspheric lens and a singlet high-index spherical lens.

4. The probe of claim 3 wherein the prism is a pyramid prism.

5. The probe of claim 1 wherein the prism has a first end, a second end, six side facets, and a centrally located aperture through the center of the prism that extends from the first end to the second end.

6. The probe of claim 5 wherein the first lens and the one or more additional lens are optically aligned to form a lens group, and a lens group is provided and optically aligned with each of the six side facets of the prism and the centrally located aperture through the center of the prism.

7. The probe of claim 1 wherein the first lens is a doublet lens and the one or more additional lens comprise at least one doublet lens.

8. The probe of claim 1 wherein the prism, the one or more additional lenses, the first lens and the one or more optic signal conductors are configured to receive a reflection of the optic signal and conduct the reflection back through the optic signal conductor.

9. A photonic Doppler velocimetry probe comprising

a housing defining an interior space;

one or more optic signal conductors within the interior space and having a terminating end configured to provide optic signals;

one or more lenses, located in the interior space of the housing, configured to receive the optic signals from the terminating end of the one or more optic signal conductors;

a refractive element configured to receive one or more optic signals from at least one of the one or more lenses, the one or more optic signals entering the refractive element in a first direction and exiting the refractive lens, after reflection off a prism facet, in a second direction, for projection onto a curved surface, the curved surface being the subject of photonic Doppler velocimetry measurement.

10. The probe of claim 9 wherein the one or more optic signal conductors comprise one or more optic fibers.

11. The probe of claim 10 wherein the housing comprises a multi-layer stainless steel housing configured hold and secure two or more lenses arranged into two more lens groups.

12. The probe of claim 11 wherein the one or more optic signal conductors are secured by a disk having one or more passages, and the one or more optic signal conductors pass through the one or more passages.

13. The probe of claim 9 wherein the reflective element comprises a prism.

14. The probe of claim 13 wherein the prism is a multi-faceted pyramid prism having two or more facets and a centrally located aperture.

15. The probe of claim 9 wherein the one or more lenses comprises at least one aspheric lens and at least one singlet high-index spherical lens.

16. The probe of claim 9 wherein the refractive element, the one or more lenses and the one or more one or more optic signal conductors are configured to receive a reflection of the optic signal and conduct the reflection back through the one or more optic signal conductors.

17. A method, during photonic Doppler velocimetry, for presenting an optic signal to a curved surface and receiving a reflection from the curved surface during movement of the curved surface comprising:

establishing a distal end of a probe facing the curved surface, the distal end of the probe including a prism having a facet, the facet facing the curved surface;

generating an optic signal;

presenting the optic signal to an optic signal conductor;

passing the optic signal through the optic signal conductor to one or more lenses;

from the lenses, directing the optic signal into the prism in a first direction, the prism reflecting the path of the optic signal to a second direction to thereby project the optic signal onto a position on the curved surface;

initiating movement of the curved surface;

receiving a reflection of the optic signal at the prism, the reflection being reflected from the curved surface;

passing the reflection through the one or more lenses to the optic signal conductor.

18. The method of claim 17 wherein the prism comprises a six faceted prism with a centrally located aperture providing an opening in the center of the prism and the one or more lenses comprise six lens groups such that six lens groups optically align with a facet of the prism and one lens group optically aligns with the aperture.

19. The method of claim 17 further comprising processing the optic signal and the reflection to perform photonic Doppler velocimetry to thereby monitor the movement of the curved surface.

20. The method of claim 17 further comprising passing the optic signal and the reflection through a circulator configured to perform as an optical directional coupler.

21. A method, during photonic Doppler velocimetry, for imaging a curved surface during movement of the curved surface, the method comprising:

establishing a distal end of a probe facing the curved surface, the distal end of the probe including image optics facing the curved surface, the image optics configured to generate a stereo image of the curved surface;

generating an optic signal;

presenting the optic signal to the image optics;

directing the optic signal through the image optics onto the surface to thereby project the optic signal onto a position on the curved surface;

initiating movement of the curved surface;

receiving an image reflection from the curved surface through the image optics and recording the image of the surface reflection with a camera.