Optical Strain Gauge Strips

• US 20090080829A1
• Filed: 06/27/2006
• Published: 03/26/2009
• Est. Priority Date: 06/29/2005
• Status: Active Grant

• Current Assignee: Hottinger Baldwin Messtechnik GmbH (Spectris PLC)
• Original Assignee: Hottinger Baldwin Messtechnik GmbH (Spectris PLC)
• Inventors: Schmidt, Michael, Blin, Regis, Haase, Karl-Heinz
• Granted Patent: US 7,720,324 B2
• Time in Patent Office: Days
• US Class Current: 385/13
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings

Abstract

The invention relates to an optical strain gage (1) for the multi-axis strain measurement, that includes at least two linear light waveguide sections (2, 3, 4) with Bragg gratings (5). These are arranged next to one another in a prescribed angle (19) of 90° or 45° on a support layer (6) and are supplied with lightwaves by a common infeeding waveguide section (7). This invention is characterized in that all light waveguide sections (2, 3, 4, 7) are provided preferably linearly on the support layer (6), and that a beam dispersion element (8) is arranged between the infeeding waveguide section (7) and the measuring waveguide sections (2, 3, 4) containing the Bragg grating (5).

Claims

1. Optical strain gage (1) for the multi-axis strain measurement that includes at least two measuring light waveguide sections (2, 3, 4) with Bragg gratings (5), which are arranged in at least one prescribed angle (19) next to one another on a support layer (6) and are supplied with lightwaves from a common infeeding waveguide (7), characterized in that all waveguide sections (2, 3, 4, 7) are embodied linearly on the support layer (6), and that a beam dispersion element (8) is arranged between the infeeding waveguide section (7) and the measuring waveguide sections (2, 3, 4).

2. Optical strain gage according to claim 1, characterized in that this is embodied as a rosette, which comprises two or three measuring waveguide sections (2, 3, 4) that are arranged next to one another and angularly offset, and that respectively include a Bragg grating (5) of differing grating period (Λ

), and that run together before the beam dispersion element (8).

12. Optical strain gage according to claim 2, characterized in that the rosette consists of two measuring waveguide sections (2, 4) that form an angle of 90°

with one another, or of three measuring waveguide sections (2, 3, 4) of which the respective neighboring two waveguide sections (2, 3, 4) form an angle (19) of 45°

with one another.

13. Optical strain gage according to claim 1, characterized in that the measuring waveguide sections (2, 3, 4) are supplied with lightwaves from a common infeeding waveguide (7), at the end of which a gradient index lens (9) and a sinusoidal transmission phase grating (10) or only a gradient index lens (9) is arranged as the beam dispersion element (8).

14. Optical strain gage according to claim 1, characterized in that all linear waveguide sections (2, 3, 4, 7) and also the beam dispersion element (8) are integrated in a thin support layer (6) that is embodied as a support film.

15. Optical strain gage according to claim 14, characterized in that the support film (6) consists of metal, glass, ceramic or a hard elastic synthetic plastic, into which guide channels (11, 18) are recessed for receiving the waveguide sections (2, 3, 4, 7) and the beam dispersion element (8), and the cross-sections of the guide channels are embodied round, cornered or angled, or V-shaped and at least comprise a diameter that corresponds to the diameter of the waveguide sections (2, 3, 4) with the Bragg gratings (5).

16. Optical strain gage according to claim 15, characterized in that the measuring waveguide sections (2, 3, 4) are embodied as optically conductive glass fibers and are pressed or glued in a force-transmitting manner in the guide channels (18) for the strain detection with the Bragg gratings (5).

17. Optical strain gage according to claim 15, characterized in that the measuring light waveguide sections (2, 3, 4) are embodied as optically conductive synthetic plastic or optically conductive glass, of which the refractive index is higher than the refractive index of the support film (6), and that are fixedly cast or inserted into the guide channels (18) and comprise a Bragg grating (5) in their end regions.

18. Optical strain gage according to claim 15, characterized in that the support film (6) is embodied quadratic or rectangular and is fixedly connected with a covering film as a cover layer (12), whereby the covering film (12) covers at least the guide channels (11, 18) with the waveguide sections (2, 3, 4, 7) and the beam dispersion element (8).

19. Optical strain gage according to claim 14, characterized in that still an additional fourth Bragg grating (13) for the temperature compensation is arranged strain-independent outside of the support film (6) in the infeeding waveguide (7).

20. Method for the production of an optical waveguide (1) according to claim 18, characterized in that at least three linear guide channels (11, 18) are worked into the support film (6) that is cut-out to a provided surface area through an etching or mechanical material removal production process, into which guide channels the measuring light waveguides (2, 3, 4) with the impressed Bragg gratings (5) and a beam dispersion element (8) as well as an infeeding waveguide (7) are secured in a force-transmitting and form-fitting manner, whereby at least the guide channels (11, 18) are sealed with a cover layer (12).

3-11. -11. (canceled)