Method for measuring article profile using electronic speckle interferometry and carrier-frequency modulation
A technology of electronic speckle interference and modulation technology, which is applied in the field of topography measurement of objects
Inactive Publication Date: 2009-08-19
SHANDONG NORMAL UNIV
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Problems solved by technology
However, the electronic speckle interferometric carrier frequency modulation measurement technology has not been applied to the shape measurement of objects.
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[0052] The test piece is a spherical crown with a diameter of 27.0 mm and a height of 0.54 mm. It is pasted on a reference plane 10 and placed on a rotatable platform. figure 1Experiments were performed on the system shown. The measured object is illuminated by the He-Ne laser through the beam expander, and the incident angle θ of the beam center is 47°. The beam expander is a 40x microscope lens, and the distance from the object to be measured is about 1.1m. Since the measured object is small and the beam expander is far away, it can be approximated that the incident illumination light is a collimated beam. When the platform is rotated by a small angle Δα ( image 3 Indicates the carrier fringe that contains the height information of the ball after the measured object is deflected. By applying Fourier transform, an envelope phase diagram containing height information can be demodulated from a carrier fringe diagram, such as Figure 4 shown. The de-enveloped phase diagram c...
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The utility model provides a method using the technology of modulating the carrier frequency of electronic speckle interference to measure the pattern of an object, used to fix a measured object on a reference plane larger than the measured object; a gap is kept between the periphery of the reference plane and the measured object; the measured object and the reference plane are deflected by a tiny angle smaller than 5 degrees, interference carrier frequency stripes are generated by use of the interference of light at the gap between the surface of the measured object and the peripheries of the measured object and the reference plane, and the interference carrier frequency stripes are collected by use of a camera, then a carrier frequency stripe diagram is obtained. The spatial frequency of the carrier frequency is calculated by use of the interference carrier frequency strip at the gap between the measured object and the periphery of the reference plane in the carrier frequency strip diagram, and the pattern information of the surface of the object can be modulated by Fourier transformation. Based on the interference of light, the utility model has an advantage of high degree of sensitivity in measurement.
Description
technical field [0001] The invention relates to a shape measurement method of an object, which belongs to the technical field of shape measurement of objects. Background technique [0002] The shape measurement of objects has a wide range of applications in the fields of robot vision, mold forming, computer-aided design, product quality inspection, and medicine, and is of great value. The shape measurement of objects has been reported in many ways, mainly including the shadow grating moiré method, the projected grating method and the digital grating method. In particular, the shape measurement technology based on Fourier transform projection grid or digital grid has high contrast, and only needs to collect one or two images to obtain the phase image of the object shape, which is easy to handle dynamically, so it has the advantages of greater practical value. The disadvantage of this method is that the measurement accuracy of the topography depends on the spatial frequency ...
Claims
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IPC IPC(8): G01B11/24G01B9/023
Inventor 孙平
Owner SHANDONG NORMAL UNIV