US 8,913,247 B2Granted

Device and method for interferometric vibration measurement of an object

AssigneePolytec GmbH

InventorsChristian Rembe, Alexander Dräbenstedt, Michael Gartner, Mike Herberich, Andreas Leonhardt

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Abstract

A device for interferometric vibration measurement, having a radiation source for generating an original beam, a first beam splitter for dividing it into measuring and reference beams, a detector and a focusing device. The measuring beam at least partly reflected by the object and the reference beam are superimposed on a detection area of the detector, and the focusing device in the beam path of the measuring beam between the image unit and object focuses it onto a measuring point. Here, a measuring beam having a wavelength greater than 1100 nm is generated and the device has an image unit for two-dimensional imaging of the object surrounding the measuring point. The measuring beam focus lies in the focal plane of the image unit and, by use of the focusing device, the focal point of the measuring beam and the focal plane of the imaging unit are displaceable simultaneously.

Claims12

Dependent claims

A device for interferometric vibration measurement on an object, comprising:

a radiation source for generating an original beam, a first beam splitter for dividing the original beam into a measuring beam and a reference beam, a detector and a focusing device,
the device is implemented in such a way that the measuring beam at least partly reflected by the object and the reference beam are superimposed on a detection area of a detector,
the focusing device is arranged in the beam path of the measuring beam, for focusing the measuring beam onto a measuring point on the object,
the device is adapted to generate a measuring beam having a wavelength greater than 1100 nm,
an image unit that provides a two-dimensional non-interferometric imaging of at least a sub-region of the object surrounding the measuring point,
the focusing device is arranged in the beam path between image unit and the object, a focus of the measuring beam lies approximately in a focal plane of the image unit, and the focal point of the measuring beam and the focal plane of the image unit are displaceable simultaneously by the focusing device,
a second beam splitter arranged in the beam path of the measuring beam between the focusing device and the detector and in the beam path of the image unit between the focusing device and the image unit that is constructed such that a loss of intensity of radiation in the visible range between focusing device and the image device is less than 50% so that the second beam splitter is transparent for light in the visible range in the beam path between the focusing device and the detector, and a loss of intensity of the measuring beam between the focusing device and the detection area of the detector is less than 50%, and
an optical lens arranged in the beam path of the measuring beam to produce a virtual focus in respect of the measuring beam, said focus being imaged by the focusing device onto the measuring point of the object.

5 more elements

A method for interferometric vibration measurement on an object, comprising the following steps:

generating an original beam from a radiation source,
dividing the original beam into a reference beam and a measuring beam using a first beam splitter,
superimposing the reference beam and the measuring beam at least partly reflected by the object on a detection area of a detector,
focusing the measuring beam using a focusing device onto a measuring point on the object,
the measuring beam is generated with a wavelength greater than 1100 nm,
at least a sub-region (A) of the object surrounding the measuring point is imaged non-interferometric and two-dimensionally by an image unit, the image unit being focused by the focusing device onto the sub-region (A) of the object, and the focusing device is constructed such that a focus of the measuring beam always lies approximately in a focal plane of the image unit,
the image unit is focused onto at least the sub-region (A) of the object and the measuring beam is simultaneously focused, at least approximately, onto the measuring point using the focusing device, and
a second beam splitter is arranged in the beam path of the measuring beam between the focusing device and the detector and in the beam path of the image unit between the focusing device and the image unit to divide the beam such that, beams at least in a visible range are guided onto the image unit to an extent of more than 50% of radiation with respect to a radiation intensity so that the second beam splitter is transparent for light in the visible range in the beam path between the focusing device and the detector, and the measuring beam reflected by the object is guided onto the detector to an extent of more than 50% with respect to the radiation intensity, and
with a lens arranged in the beam path of the measuring beam a virtual focus is produced in respect of the measuring beam and said focus is imaged by the focusing device onto the measuring point of the object.

6 more elements

Dependencies are inferred from the claim text.