Self calibration method for image measuring instrument

Abstract

The invention discloses a self calibration method for an image measuring instrument. According to the method, on the basis of the correlation theory of mathematic images, two adjacent images of a tested workpiece before or after the translation in a two-dimensional plane are used as objects, the pixel displacement value is calculated, then, the reading value of a grating ruler during the image collection is combined, the practical physical size displacement value is obtained, finally, the scale factor of the image measuring instrument is obtained according to the ratio of the pixel displacement value to the practical physical size displacement value, and the self calibration of the image measuring instrument is realized. The self calibration method does not need a special-customized high-precision calibration plate and has the advantages of simple and convenient operation and high efficiency, the image measuring instrument can be fast calibrated in any time, and in addition, the cost is saved.

Description

technical field [0001] The invention relates to the field of calibration methods for video measuring instruments, in particular to a self-calibration method for video measuring instruments. Background technique [0002] Image measurement technology is a category that requires quantitative measurement in visual inspection, and the focus of research is on the measurement of geometric quantities of objects. With the advancement of science and technology, the most typical product of this technology, that is, the image measuring instrument that uses the non-contact image probe for measurement, has been gradually accepted by many industries. After decades of development, the application range of image measuring instruments has been continuously expanded, and it has the ability to precisely measure complex workpiece contours and surface shapes. [0003] For the image measuring instrument, the core task in the pre-measurement preparation is calibration, which is the bridge to estab...

AI Technical Summary

Problems solved by technology

[0005] Although the standard part method has been developed relatively maturely and has high precision, this method highlights the shortcomings of cumbersome and time-consuming operation when the magnification of the microscope lens needs to be changed frequently

In addition, due to the small field of view of the image measuring instrument, it is difficult to manufacture calibration plates with excellent performance and is expensive. In addition, these high-precision calibration plates are easily polluted and worn during use, which affects the calibration accuracy. affect, and ultimately affect the measurement results of the measuring instrument

Images