A measuring device for the optic measuring of an object 13a is provided, in particular for measuring a motion of the object. The device includes an interferometer 20 with a measuring beam exit 12, a reflection beam entry 14, an interfering beam exit 15, and a light source 1 for creating a light beam 8, an optic detector 16, which is arranged at the interfering beam exit 15 of the interferometer 20 such that a light beam exiting the interfering beam exit 15 impinges the detector and a signal processing unit 17 connected to the detector 16 being embodied such that they can measure measuring signals of the detector 16. The interferometer (20) is provided with a switched beam entry (18) and is embodied such that dependent on a switching signal connected to a switched beam entry (18) a light beam exits the measuring beam exit (12) essentially with a predetermined light intensity and at a predetermined angle, and that the signal processing unit (17) is provided with a switched beam exit, which is connected to the switched beam entry (18) of the interferometer, with the signal processing unit (17) controlling the interferometer such that a light beam exits the measuring beam exit (12) only during the measuring of measuring signals essentially with a predetermined light intensity and at a predetermined angle.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, an exemplary embodiment is explained in greater detail using the attached drawing. Shown is:
FIG. 1 a schematic view of an exemplary embodiment of the measuring device according to the invention, with the optic switching element being embodied as a Bragg cell in combination with a radiation trap.
Claims
1. A measuring device for optical measuring of an object (13a), in particular for measuring a motion of the object (13a), comprising an interferometer (20) with a measuring beam exit (12), a reflection beam entry (14), an interference beam exit (15), and a light source (1) for creating a light beam (8), with the interferometer (20) being embodied such that the light beam (8) created by the light source (1) is split into at least first and second partial beams (9, 10), with the first partial beam (9) exiting the measuring beam exit (12) essentially at a predetermined angle and the second partial beam (10) being interfered with a reflection beam entering through the reflection beam entry (14), and the second partial beam (10) exiting with the interfered reflection beam at the interference beam exit (15), an optic detector (16), which is arranged at the interference beam exit (15) of the interferometer (20) such that a light beam exiting the interfering beam exit (15) impinges the detector (16), and a signal processing unit (17), which is connected to the detector (16) and embodied to collect and/or process measuring signals of the detector (16), the interferometer (20) is provided with a switched beam entry (18) and embodied such that depending on a switching signal connected to the switched beam entry (18), the light beam exits the measuring beam exit (12) essentially at a predetermined light intensity and at a predetermined angle and the signal processing unit (17) is provided with a beam switching exit, which is connected to the beam switching entry (18) of the interferometer, with the signal processing unit (17) being embodied to control the interferometer such that the light beam essentially with the predetermined light intensity only exits the measuring beam exit (12) during a measuring of measuring signals for taking measurements and at the predetermined angle.
2. A measuring device according to claim 1, wherein the interferometer is provided with a dimmer unit, which is arranged in a radiation path of the measuring beam and connected to the switched beam entry (18), the dimmer unit being embodied such that when the switching signal is connected the measuring beam passes through the dimmer unit without any essential loss of intensity, while when no switching signal is connected to the dimmer unit, an intensity of the measuring beam is reduced by a predetermined factor by the dimmer unit.
3. A measuring device according to claim 2, wherein the dimmer unit is embodied such that when no switching signal is connected the intensity of the measuring beam is reduced by at least 90%.
4. A measuring device according to claim 3, wherein the dimmer unit is embodied to block the measuring beam when no switching signal is connected.
5. A measuring device according to claim 1, wherein the signal processing unit (17) is embodied to measure measuring signals of the detector (16) at least for a term tmin, with tmin being equivalent to an inverse of a predetermined minimum frequency fmin.
6. A measuring device according to claim 1, wherein the signal processing unit (17) is embodied to measure measuring signals of the detector (16) for a period no longer than a predetermined maximum term tmax.
7. A measuring device according to claim 6, wherein tmax is calculated from the formula
8. A measuring device according to claim 7, wherein values are selected for the material parameters ρ, c, a, and η, which are essentially equivalent to material parameters of the object to be measured.
9. A measuring device according to claim 7, wherein the measuring beam diameter dM is equivalent to a diameter of the measuring beam exiting the interferometer (20) at the measuring beam exit (12).
10. A measuring device according to claim 7, wherein the interferometer (20) comprises a focusing device (7), which is arranged in the radiation path of the interferometer (20) such that the measuring beam exiting at the measuring beam exit (12) is focused, and the light source (1) of the interferometer (20) is embodied to create an essentially monochromatic light beam (8) with a wave length λ or a light beam with partial light beams of several wave lengths, with for example λ being an average value of the wave lengths of the partial light beams, and that the diameter dM of the measuring beam is predetermined by the formula
11. A measuring device according to claim 7, wherein the predetermined length l amounts to at least dM.
12. A measuring device according to claim 7, wherein the predetermined maximum temperature difference T amounts to a maximum of 500° C.
13. A measuring device according to claim 6, wherein the signal processing unit (17) is embodied to perform at least two measuring processes with one collection of the measuring signals each, with a pause of at least a predetermined period tP being performed between the two measuring processes, in which no collection of measuring signals occurs, and no switching signal is emitted to the switched beam entry (18) of the interferometer (20), with tP being at least
14. A measuring device according to claim 1, wherein the signal processing unit (17) is embodied to emit a switching signal to the switched beam entry (18) of the interferometer (20) for the lead-time tvor prior to the collection of measuring data.
15. A measuring device according to claim 1, wherein the interferometer (20) comprises an optic switching element, which is connected to the switched beam entry (18) of the interferometer (20) and arranged in the radiation path of the interferometer, when a switching signal is connected, a measuring beam exits the measuring beam exit (12) of the interferometer (20) essentially at a predetermined angle and, when no switching signal is applied, no measuring beam exits the measuring beam exit (12) of the interferometer (20) at the essentially predetermined angle.
16. A measuring device according to claim 15, wherein the optic switching element is comprises a Bragg cell (11) or as a mechanical shutter.
17. A measuring device according to claim 15, wherein the optic switching element comprises an electro-optic shutter.
18. A measuring device according to claim 1, wherein the measuring device comprises a vibrometer.
19. A measuring device according to claim 18, wherein the vibrometer comprises a heterodyne interferometer.
20. A measuring device according to claim 18, wherein the measuring device comprises a scanning confocal laser-Doppler vibrometer.
21. A method for the optic measuring of an object (13a), in particular for measuring motion of the object, comprising:
a) creating a laser beam and splitting the light beam into at least one measuring beam and one reference beam,b) impinging a measuring point (15) on the object (13a) with the measuring beam,c) interfering the measuring beam reflected by the object with the reference beam such that the reflected measuring beam with the interfering reference beam impinges an optic detector (16) and,d) measuring the measuring signals of the detector (16),wherein the measuring process in step d) is performed at least for a term Tmin, with the object (13a) during said term being lit with the measuring beam and tmin being equivalent to an inverse of a predetermined minimum frequency fmin, and that immediately after the measuring process in step d) reducing an intensity of the measuring beam by a predetermined factor.
22. A method for optically measuring an object according to claim 21, wherein immediately after the measuring process in step d) the intensity of the measuring beam is reduced by at least a factor of 10, in particular by at least a factor of 50, and most particularly by a factor of 100.
23. A method for the optic measuring of an object according to claim 21, wherein immediately after the measuring process in step d) the measuring point is no longer lit with the measuring beam.
24. A method for the optic measuring of an object according to claim 21, wherein the measuring process in step d) lasts a period of no longer than a maximum predetermined term tmax.
25. A method for the optic measuring of an object according to claim 24, wherein tmax is calculated from the formula
26. A method for the optic measuring of an object according to claim 25, wherein values are selected for the material parameters ρ, c, a, and η which essentially are equivalent to material parameters of the object (13a) to be measured.
27. A method for the optic measuring of objects according to claim 25, wherein the diameter dM of the measuring beam is essentially equivalent to a diameter of the measuring beam impinging the object (13a) at the measuring point (13).
28. A method for the optic measuring of an object according to claim 25, wherein the measuring beam is focused on the measuring point (13) on the object (13a) via a focusing device, and the measuring beam is essentially monochromatic with a wave length λ or a light beam with partial light beams of several wave lengths, with λ being an average of the wave lengths of the partial light beams, and with the diameter dM of the measuring beam being predetermined by the formula
29. A method for the optic measuring of an object according to claim 25, wherein the predetermined length l is at least dM.
30. A method for the optic measuring of an object according to claim 25, wherein the predetermined maximum temperature difference T amounts to no more than 500° C.
31. A method for the optic measuring of an object according to claim 24, wherein in step d) at least two measuring processes are performed, in which the measuring signals of the detector are measured each, with a pause of at least a predetermined term tP being performed between the two measuring processes, in which no measuring signals are being measured, and the measuring point (13) on the object (13a) is not impinged with the measuring beam, where tP amounts to at least
32. A method for the optic measuring of an object according to claim 23, wherein in step d) the measuring signals of the detector (16) are only measured after a lead-time tvor, with the measuring point (13) on the object (13a) being lit by the measuring beam during tvor.
33. A measuring device according to claim 8, wherein the material parameters ρ, c, a, and η are selected for a silicon material as ρ being approximately 2.33 kg/m3, c being approximately 670 J/kg/K, a being approximately 1, and η being approximately 160 W/m/K.
34. A method for the optic measuring of an object according to claim 26, wherein values are selected for a silicon material as ρ being approximately 2.33 kg/m3, c being approximately 670 J/kg/K, a being approximately 1, and η being approximately 160 W/m/K.
Patent Application
20070177154
