CN101556141A - Fourier transformation method for measuring irregular slit width and device - Google Patents
Fourier transformation method for measuring irregular slit width and device Download PDFInfo
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- CN101556141A CN101556141A CNA2009100844983A CN200910084498A CN101556141A CN 101556141 A CN101556141 A CN 101556141A CN A2009100844983 A CNA2009100844983 A CN A2009100844983A CN 200910084498 A CN200910084498 A CN 200910084498A CN 101556141 A CN101556141 A CN 101556141A
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Abstract
The invention discloses a Fourier transformation method for measuring irregular slit width and a device thereof. The method comprises the following steps of: adjusting the position of a light source and reflecting the received light source; adjusting the distance between a lens and a slit to be measured; obtaining a whole image of the slit to be measured; transforming the acquired image information into digital information and storing correspondingly; reading data; implementing corresponding operation on the read data; and then obtaining the slit width of the current measured slit. The device comprises a light source, a lens and a CCD, an image acquisition and data storage module, a data read unit, a Fourier transformation and processing unit and a personal computer (PC). The device has simple structure, is applicable to measuring the geometric dimensions of widths and shapes and the like of slits and grooves with irregular shapes, uneven widths or gradient widths and non-liner direction; and in different measurements, non-contact measurement with precision and fastness can be realized without changing amplification factor of the lens, namely the resolution of CCD.
Description
Technical field
The present invention relates to a kind of Fourier transformation method and device thereof of measuring irregular slit width, relate in particular to a kind of method and device that utilizes the Fourier transform image data processing, measures the width of various irregular slits and groove.
Background technology
Various slits, slit, cutting can be run in the commercial production, the measurement and the control of width, spacing, shape etc. need be carried out.When spending as the light leak of piston ring in the detection of engine, need piston ring is pressed into ring gauge, if piston ring has light leak, then piston ring outer rim and ring gauge are interior intermarginally will form the uneven circular-arc slit of width; In various welding, often need the width of butt welded seam to measure, so that the control welding process obtains best welding effect; Being used for the plug wire jig of strip off electric wire overcoat has the draw-in groove gap of V-type, is to guarantee that the plug wire card can operate as normal, and there are strict requirements to the gap of specific location on the draw-in groove; The finedraw applicator is a kind of substrate board treatment that is used to make printed circuit board (PCB), and the finedraw applicator sprays treating fluid during work from nozzle, for guaranteeing the homogeneity of ejection treating fluid, requires the aperture pitch of nozzle high-precision evenly; In addition, as long as all can form the slit between two close objects.Measurement to these gap widths, shape etc. has important use to be worth and practical significance to evaluation product quality, CONTROL PROCESS flow process.
Measurement to gap width has contact and contactless two kinds of methods, and the contact method adopts various measurers to measure, but needs manually-operated, and automatization level is low, and measuring accuracy is subjected to the restriction of measurer precision and is difficult to improve.Contactless method comprises multiple, the measuring accuracy height of tool microscope wherein, but cost height, volume big, be unsuitable for industry spot and use; And utilize CCD to take the image in slit, the method that obtains gap width, shape through Flame Image Process have volume little, use flexibly, be suitable for advantage such as on-the-spot use.
At present, the method for measuring the slit by CCD photographic images and application image treatment technology also can be divided into two kinds: first kind of employing thrown light on dorsad, and utilizes diffraction effect, and the seam of deriving from the light distribution of diffraction pattern is wide; Second kind is adopted front illumination, two edges forming the slit are imaged on the CCD simultaneously, because the low-pass effect of imaging system, the edge is no longer clear and legible and become a confusion region, if will measure the spacing at two edges forming the slit, existing method is at first to improve the resolution of CCD, make the confusion region of two edges on image be separated, remake Flame Image Process, finish the wide measurement of seam, just being to use enlargement factor as domestic patent " roller mouth measurement method for distance and sensor " (application number 200310118466.3) is 60 camera lens, to improve the resolution of CCD and image, finishes measurement.First method exists the errors of principles (the thin cylinder diameter Measurement Uncertainty of [1] optical diffraction method, Cui Jianwen, Zhang Jun etc., photoelectric project, 2005,7:55-58), and the slit after the imaging can not reflect the details of actual gap, and measured result is the mean breadth of slit in a segment length.Second method all will be adjusted camera lens as required in each measurement the enlargement ratio is the resolution of CCD, and bring three drawbacks thus: after 1. adjusting the enlargement ratio of camera lens, for can obtain again clearly as, must adjust camera lens simultaneously to the distance between testee, these adjustment processes can prolong Measuring Time; 2. adjust light path and need be equipped with corresponding governor motion, this must increase the cost and the volume of measurement mechanism; 3. along with the increase of camera lens enlargement ratio, the measurement visual field of CCD will reduce, and the time of finishing whole measurements will prolong thereupon.In sum, all there are certain limitation in existing method, instrument, can't fine solution slit, and the problems of measurement of physical dimensions such as the width in especially irregular slit, shape.
Summary of the invention
For solving above-mentioned middle problem and the defective that exists, the invention provides a kind of CCD of utilization imaging and also finish the method and the device of measurement with the Fourier transform deal with data, not only realized irregular slit physical dimensions such as width, shape fast, accurately measure, and on the basis that does not increase measurement links and measuring sensor, keep the resolution of CCD constant, reach fast and accurately measure, avoid the influence of Light Diffraction Effect simultaneously.
The present invention is achieved by the following technical solutions:
A kind of Fourier transformation method of measuring irregular slit width involved in the present invention comprises:
Adjust the position of light source, the object that constitutes tested slit reflects the light source that receives;
Adjust the distance between camera lens and tested slit;
Obtain the entire image in tested slit;
The image information that collects is converted to numerical information, and stores accordingly;
Data are read;
The data that read are carried out corresponding computing, and the seam that obtains current tested slit is wide.
A kind of Fourier transform device of measuring irregular slit width involved in the present invention comprises:
Light source is used to shine tested slit, and the object that constitutes tested slit reflects light;
Camera lens and CCD receive the tested slit reflected light of object on every side, obtain the image in whole tested slit;
Image acquisition and data storage cell are converted to numerical information with the image information among the CCD, and its numerical information is stored;
Data-reading unit, along with seam move towards perpendicular direction reading of data, and the data that read are sent to Fourier transform and processing unit;
Fourier transform and processing unit are handled and computing accordingly to the data that read, and the seam that obtains tested slit is wide.
The beneficial effect of technical scheme provided by the invention is:
1, two strip light sources shine slit to be measured from the both sides oblique upper respectively, and the illumination of all even brightness abundance can be provided for multiple measuring object;
2, in different measurements, need not change the resolution of CCD, reduce measurement links, shortened Measuring Time;
3, light source is consistent with the service band of CCD, has reduced picture noise;
4, Fourier transform and processing unit utilize the Fourier transform deal with data, extract the wide information of seam the view data after fuzzy by imaging system, not only finish the measurement of slit physical dimension, can also recover its image in the ideal case, and calculate relevant evaluation index.
Description of drawings
Fig. 1 is a method flow diagram provided by the invention;
Fig. 2 is Fourier transform and processing flow chart;
Fig. 3 is the process flow diagram of calculating pixel equivalent;
Fig. 4 is the bright structural representation of this law;
Fig. 5 a and 5b are the differentiation synoptic diagram of tested slit in measuring process.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, embodiment of the present invention is described further in detail below in conjunction with accompanying drawing:
Embodiment 1
Present embodiment provides a kind of Fourier transformation method of measuring irregular slit width.
Referring to Fig. 1, this method may further comprise the steps:
The adjustment of described light source is that the position in tested relatively slit is adjusted, and two light sources are to be symmetry status with respect to the slit to place, and from both sides oblique upper irradiation slit, provides the even illumination of brightness abundance for field of view respectively.
Make under current focal length and image distance, can access the sharply defined image in slit.
Speed and time by the image acquisition that is provided with in the PC and data memory module control image acquisition, obtaining preserving under the order of image, by the path of PC designate storage.
The view data of step 105 pair storage is carried out visualization display.
Not only obtain the measurement of physical dimensions such as gap width, can also recover its image in the ideal case, and calculated relevant evaluation index.
Finish execution in step 109, otherwise execution in step 106 if read.
Described packet contains many groups, reads wherein one group at every turn, and reading of data is under the control of PC, by data-reading unit along with the perpendicular direction reading of data of moving towards of seam, and the data that read are sent to Fourier transform and processing unit.
Referring to Fig. 2, the Fourier transform that present embodiment provides and the algorithm flow of processing, this flow process may further comprise the steps:
The step 201 pair view data that reads is filtered and is made an uproar;
It mainly is the filtering obvious noise that described filter is made an uproar.
Suitable origin position has made things convenient for follow-up data processing.
It is wide that step 204 selects some special coordinates points, the Fourier transform value at special coordinates point place to comprise the seam of current location.
The coordinate system that step 206 constitutes at suitable true origin is sought the geometrical constraint condition.
Step 207 is found the solution the system of equations that special coordinates point simultaneous constitutes under the condition of geometrical constraint.
Step 208 is according to the condition with geometrical constraint found the solution of system of equations, obtain the wide and value of relevant information on image of current location seam, again according to the pixel equivalent (ratio of the quantity of the size of known object and the pixel of record that calculates, see Fig. 3 for details), obtain the actual amplitudes of stitching wide and relevant information, and can recover tested slit intensity profile image in the ideal case, promptly eliminate imaging system to the fogging action of image and the ideal image behind the elimination noise, also can calculate relevant evaluation index simultaneously, as square error, signal to noise ratio (S/N ratio) etc.
Step 209 is with the measurement result output of needs;
Described result comprises the wide value of seam, the ideal image after recovering, evaluation index etc.
Referring to Fig. 3, the flow process that obtains pixel equivalent is provided, when lens focus fix and with the relative position of CCD fixing after, when actual object is of a size of a pixel equivalent, imaging just is a length in pixels on CCD.Idiographic flow may further comprise the steps:
Step 301 fixed lens focal length and image distance;
Described fix image distance and focal length after, will not change in thereafter measurement mid-focal length and image distance.
Step 302 is selected object image-forming;
Selection has the object of known dimensions, and known dimensions should be the large-size that is easy to measure, and uses focal length, fixing camera lens and the CCD2 of image distance that it is taken pictures, and changes size into image information.
Step 303 is regulated operating distance;
Described operating distance is a camera lens to the distance of selected object, for reducing error, this distance make as far as possible become clear picture.
The quantity of step 304 document image respective pixel;
Known dimensions is corresponding on the quantity of the pixel of described record and the object.
Step 305 obtains pixel equivalent;
The ratio of the pixel quantity of known dimensions and record promptly is pixel equivalent.
The tested slit that present embodiment provides can be the slit in the same object, also can be two slits (distance is close between two different objects, but when not contacting formed slit) between different objects.
Embodiment 2
Present embodiment also provides a kind of Fourier transform device of measuring irregular slit width.
Referring to Fig. 4, the Fourier transform device of measuring irregular slit width comprises: light source 10, camera lens and CCD30, image acquisition and data storage cell 40, data-reading unit 50, Fourier transform and processing unit 60 and PC 70.Described light source comprises two identical strip light sources, is made of light emitting diode, and the ruddiness that output is uniform in the space shines tested slit 20 from the both sides oblique upper respectively, and the even illumination of brightness abundance is provided for field of view; What camera lens and CCD received is the reflected light of object around the tested slit, obtain from the front whole slit clearly as; Image acquisition and data memory module under PC control, are converted to CCD numerical information with image information, and are stored in the corresponding disk of PC; Data-reading unit is under PC control, along with seam move towards perpendicular direction reading of data, and send into Fourier transform and processing unit, the seam of knowing the slit current location by respective algorithms is wide, data-reading unit reads one group of data of another location on the slit again, finish the wide measurement of seam on this position again after sending into Fourier transform and processing unit, this process constantly circulates, the measurement of the wide physical dimension of seam in slit in finishing user's specified scope.
Referring to Fig. 5 a and Fig. 5 b, be the structural representation that tested slit develops in measuring process, diffuse reflection takes place in tested slit 20 under the even illumination of light source, and reflected light becomes plane picture 502 after being received by camera lens and CCD; Under the control of PC, image acquisition and data memory module are converted to two dimensional gray matrix 503 with image 502, and are stored in the corresponding disk of PC; Under PC control, data-reading unit reads one group of data in the somewhere, slit, data 504 of ab section in the plane picture 502 for example, and this is one group of discrete gray-scale value, the interval of discrete point is by the Pixel Dimensions decision of the enlargement ratio and the CCD of camera lens, simultaneously inevitably by noise pollution; Under PC control, data are admitted to Fourier transform and processing unit, and the seam that is recorded current location by respective algorithms is wide, and recover ideally the slit and calculate the relevant evaluation index in the intensity profile 505 of current location; Under PC control, data-reading unit constantly reads new data, is handled accordingly by Fourier transform and processing unit, finishes whole measurements.The present invention can measure the synoptic diagram of various slit surfaces patterns, comprises out-of-shape, width is inhomogeneous or the seam of width gradual change, non-rectilinear trend and the measurement (as Fig. 5 b) of groove.
The tested slit that present embodiment provides can be the slit in the same object, also can be two slits (distance is close between two different objects, but when not contacting formed slit) between different objects.
Though described the present invention by embodiment, the present invention does not break away from spirit of the present invention by many distortion and variation, and claim of the present invention comprises these distortion and variation.
Claims (8)
1, a kind of Fourier transformation method of measuring irregular slit width is characterized in that, this method comprises:
Adjust the position of light source, the object that constitutes tested slit reflects the light source that receives;
Adjust the distance between camera lens and tested slit;
Obtain the entire image in tested slit;
The image information that collects is converted to numerical information, and stores accordingly;
Data are read;
The data that read are carried out corresponding computing, and the seam that obtains current tested slit is wide.
2, the Fourier transformation method of measurement irregular slit width according to claim 1 and 2 is characterized in that, described is to read along the perpendicular direction moved towards with seam by reading unit to reading of data.
3, the Fourier transformation method of measurement irregular slit width according to claim 2 is characterized in that, the data that described data-reading unit reads include many groups.
4, the Fourier transformation method of measurement irregular slit width according to claim 1 is characterized in that, described data are read also comprises before:
View data to storage is carried out visualization display;
Judging whether the data that read belong in the scope of measurement, is that data are read; Otherwise, read next group data.
5, a kind of Fourier transform device of measuring irregular slit width is characterized in that this device comprises:
Light source is used to shine tested slit, and the object that constitutes tested slit reflects light;
Camera lens and CCD receive the tested slit reflected light of object on every side, obtain the image in whole tested slit;
Image acquisition and data storage cell are converted to numerical information with the image information among the CCD, and its numerical information is stored;
Data-reading unit, along with seam move towards perpendicular direction reading of data, and the data that read are sent to Fourier transform and processing unit;
Fourier transform and processing unit are handled and computing accordingly to the data that read, and the seam that obtains tested slit is wide.
6, the Fourier transformation method of irregular slit width according to claim 5 is characterized in that, described light source comprises two strip light sources, and two strip light sources constitute by light emitting diode, and shines tested slit from the both sides in tested slit respectively.
7, the Fourier transformation method of irregular slit width according to claim 5 is characterized in that, described CCD is the image that obtains whole slit from the front.
8, the Fourier transformation method of irregular slit width according to claim 5 is characterized in that, the data that described data-reading unit reads include many groups, whenever after reading wherein one group of data, judge data in the measurement range whether read finish after, be that the result is read in output; Otherwise read next group data.
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| CNA2009100844983A CN101556141A (en) | 2009-05-20 | 2009-05-20 | Fourier transformation method for measuring irregular slit width and device |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102175167A (en) * | 2010-12-29 | 2011-09-07 | 吴江市博众精工科技有限公司 | Method for measuring fastening condition of upper cover and lower cover |
| CN106645181A (en) * | 2017-02-24 | 2017-05-10 | 清华大学 | Microscopic vision-based roller grinding surface defect detecting system |
| CN110726372A (en) * | 2019-09-24 | 2020-01-24 | 南京工程学院 | Method for accurately processing single-slit diffraction image |
| CN111336939A (en) * | 2020-03-13 | 2020-06-26 | 安标国家矿用产品安全标志中心有限公司 | Machine vision-based online detection method and device for gap between explosion-proof joint surfaces |
| CN112902852A (en) * | 2021-01-25 | 2021-06-04 | 上海兰宝传感科技股份有限公司 | Device and method for detecting size of micro object |
| CN113483682A (en) * | 2021-06-16 | 2021-10-08 | 苏州赛腾精密电子股份有限公司 | Gap measuring method and system based on machine vision |
-
2009
- 2009-05-20 CN CNA2009100844983A patent/CN101556141A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102175167A (en) * | 2010-12-29 | 2011-09-07 | 吴江市博众精工科技有限公司 | Method for measuring fastening condition of upper cover and lower cover |
| CN106645181A (en) * | 2017-02-24 | 2017-05-10 | 清华大学 | Microscopic vision-based roller grinding surface defect detecting system |
| CN110726372A (en) * | 2019-09-24 | 2020-01-24 | 南京工程学院 | Method for accurately processing single-slit diffraction image |
| CN110726372B (en) * | 2019-09-24 | 2021-05-11 | 南京工程学院 | Method for accurately processing single-slit diffraction image |
| CN111336939A (en) * | 2020-03-13 | 2020-06-26 | 安标国家矿用产品安全标志中心有限公司 | Machine vision-based online detection method and device for gap between explosion-proof joint surfaces |
| CN112902852A (en) * | 2021-01-25 | 2021-06-04 | 上海兰宝传感科技股份有限公司 | Device and method for detecting size of micro object |
| CN113483682A (en) * | 2021-06-16 | 2021-10-08 | 苏州赛腾精密电子股份有限公司 | Gap measuring method and system based on machine vision |
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Open date: 20091014 |