TW201027157A - System and method for focusing on multiple surface of an object - Google Patents

Abstract

The present invention provides a method for focusing on multiple surface of an object. The method includes: selecting a surface to be focused on from an image of an object to be measured, a focus position of the selected surface, and a focus area of the selected surface; searching a rough focal point; moving a CCD lens in a specified distance, obtaining the image of the object to be measured and an Z-axis coordinates of the CCD lens; calculating a definition of each obtained image at the focus area; filtering the definition of the obtained image and the Z-axis coordinates of the CCD lens; ordering the filtered Z-axis coordinates of the CCD lens, so as to obtain new Z-axis coordinates of the CCD lens and new definition of each obtained image; calculating an accurate focal point according to the selected surface to be focused, the new Z-axis coordinates and the new definitions; moving the CCD lens to the accurate focal point. A system for focusing on multiple surface of an object is also provided. The present invention can focus on a selected surface of an object to be measured.

Description

201027157 * VI. Description of the Invention: [Technical Field] The present invention relates to an image measuring system and method, and more particularly to a multiple surface focusing system and method. * [Prior Art] Image measurement is currently the most widely used measurement method in the field of precision measurement. This method not only has high precision, but also has fast measurement speed. Image measurement is used to measure the dimensional error and shape error of the workpiece (part or part), which plays an important role in ensuring product quality. In general, the image measurement method uses an image measuring machine, such as VMS (Vision Measuring System), to capture the image of the workpiece to be tested, and then transmits the acquired workpiece image to the host through the measurement software pair in the host. The workpiece image is further processed. Before measuring the contour or surface height of the workpiece to be tested, it is usually necessary to perform image focusing 'the distance of the surface of the workpiece to be tested to the CCd (Charge Coupled ❿ Device) lens is equal to the focal length. The previous image autofocus method was to move the CCD lens within a certain range and continuously acquire the image of the upper surface of the workpiece to be tested, and then calculate the focus position of the CCD lens based on the acquired image data. However, this method cannot distinguish between the image of the upper surface of the workpiece to be tested and the image of the lower surface. If the workpiece to be tested is a transparent thin piece, the upper and lower surfaces of the workpiece to be tested are automatically focused by the & method. The image may be acquired by the CCD lens, resulting in an inaccurate focus position of the calculated CCD lens. For example, the CCD lens should be focused on the upper surface, but the result of the focus is the lower surface, or the CCD lens should be focused on the surface of the table below 201027157, but the result is the upper surface. SUMMARY OF THE INVENTION In view of the above, there is a method that can be focused from (4) "k multi-surface focusing system and a certain surface of the workpiece to be tested. The evening surface focusing system" includes a host computer and an image measuring machine a. The host includes: Select the fine mj profit machine, ^^ , , , ' for the scene of the workpiece to be tested taken in the image measuring machine, select the focus in the image (4) Zheng 隹μ~m focus position and focus range ; Rough ❹ Used to control the image measuring machine: Rough focus position; Accurately find the 隹w... for controlling the cc D lens: The z-axis direction continuously intercepts the image of the workpiece to be tested and the CCD, and the correct focus module is also used to select each of the captured images to be measured, centering on the selected focus position, and selecting the focus range The size of the area 'calculates the area of the area as the sharpness of the image; the capital (four) rational module 1 filters the sharpness of the color image and the axis coordinates of the corresponding CCD lens according to the mean value over money algorithm; Module, also used Performing equidistant refinement on the ζ-axis coordinates of the filtered CCD lens to obtain a new 2-axis coordinate and new image definition; the precise focus module is also used according to the selected focus surface, the new ζ axis The library mark and the new image sharpness, calculate the precise focus position, and move the ccx> lens to the precise focus position. A multi-surface focusing method, the method includes the following steps: the sample to be taken at the image measuring machine Select the focus surface, focus position and focus range in the image of the workpiece; control the CCD lens movement of the image measuring machine to find 5 201027157 rough focus position; control the CCD lens to focus on the a focus from the focus position of the CCD In the precise distance of the setting, the Z-axis coordinate is moved from the 卞 to the top in the Z-axis direction; the image of the workpiece to be tested taken by the hanging mother is selected with the selected 'and the extended position as the center. The area of the range is calculated, and the resolution of the image is calculated; the Z-axis coordinate of the corresponding CCD lens is filtered according to the mean filtering algorithm; and the Z-axis coordinate of the CCD lens after the passing is performed. Isometric refinement, new Z-axis coordinates and new image sharpness; accurate focus position based on selected focus surface, new Z-axis coordinates and new image sharpness; moving CCD lens to precise Focus position. Compared with the multi-surface focusing system and method described in the prior art, it can focus on the surface of the workpiece to be tested, and the accuracy of image focusing is improved.

Referring to Figure 1, there is shown a system architecture diagram of a preferred embodiment of the multiple surface focusing system of the present invention. The system mainly includes a display device 1, a host 2, an image measuring machine 3 and an input device 4. The main body 2 includes a storage body 20 and a surface focusing grass unit 21 °. The composition of the image measuring machine 3 is shown in FIG. 2, and the image measuring machine is combined in the X-axis, the Y-axis, and the z-axis direction. Each of the women's wear has a motor (not shown in FIG. 2), and the main components thereof include a machined top cover 31, a CCD lens 32, a machine less face 33, and a machine main body 34, which are placed on the machine work surface 33. Pending 剁> piece 35. The CCD lens 32 is configured to take an image of the workpiece 201010157 35 (including the image), and send the image of the upper surface of the captured object and the storage body 2〇3 of the lower surface to the host. 2° Focus data 22. The hard disk or the like in the host 2 is used for storing the image of the sharpness and the CCD lens 3; and the image of the workpiece 35 to be tested, in addition to the CCD lens π#^. Element 21 through the control and the axis ^ focus process, the surface focus sheet

^i® u / yt and the movement of the Y-axis motor, thereby changing the machine face 33 in the X-axis and γ-axis directions, ie, the level direction) == (the χ axis and the rough focus position in this embodiment) However, t γ _CCD _32 moves .^ . . . , U., moxibustion, and the surface focusing unit 21 controls the movement of the Z-axis horse % # ^ so that the 01 lens 16 is accurately focused on the upper surface or the lower surface of the workpiece 35 to be tested. The display unit i is connected to the display device i for displaying an image of the image measuring machine port ^ transmitted to the host 2. The input area 4 can be a keyboard, a mouse, etc., for data registration. The surface focusing unit 21 includes a selection module 21〇, a coarse focusing module 211, a precision focusing module 212, and a data processing module. The module referred to in the present invention is a complete-specific function of the age-old segment. The program is more suitable for describing the execution process of the software in the computer, so the following description of the present invention is described by a module. The selection module 210 is used for the workpiece 35 to be tested taken by the image measuring machine 3. The focus surface, the focus position, and the focus range are selected in the image. In this embodiment The focusing surface includes an upper surface and a lower surface of the workpiece 35 to be tested, the length of the focusing range is W, and the width is η (for example, 3 〇mm, 201027157 Η is 20 mm). The coarse focusing module 211 is used for Control the ccd lens & 〇哥 to find a rough focus position. Specifically, the coarse focus module lens 32 is centered on the selected focus position, within the set rough = within (the rough distance can be set according to the measurement requirements, For example, 2 moves from top to bottom along the Z-axis direction, and continuously wears the image of the workpiece to be tested and the Z-axis coordinate of the CCD lens 32. Then, for each image of the workpiece 35 to be tested, the selected focus is selected. The position is t center, and the area of 2 range (W*H) is selected, and the sharpness of the area is calculated as the sharpness of the t image. Finally, the coarse focus module 211 selects the axis coordinate corresponding to the image with the largest sharpness value. As a rough focus position, the more the corresponding Ζ axis of the image refers to the Z-axis coordinate of the CCD lens 32 when the image is intercepted. Referring to Figure 3, the schematic diagram of calculating the image sharpness of the present invention is assumed. (i,j) generation - a primitive point in the image, D(i,j) represents the sharpness of the point of the primitive, then 1,j) = Abs(Gray(i+l,j) _ Grayd J·)) + AbS (Gray(i, j + l)_Gray(i, H)). Among them, Abs〇 represents the absolute value function, and Gray(i,j) represents the gray value of the primitive point P(i,j). Add the sharpness of all the feature points in the focus range (W*H) to get Def au = ^^D(i, j), and then divide by the number of primitive points in the focus range to get an average value. The sharpness of the image. The precise focus module 212 is configured to control the CCD lens to be centered on the coarse focus position within a set precise distance (the precise distance is less than the rough distance, and can be set according to the measurement requirement, such as 8 201027157 10 mm) The z-axis direction is moved from bottom to top, and the image of the workpiece 35 and the Z-axis coordinate of the CCD lens 32 are continuously intercepted. Then, for each image of the workpiece 35 to be tested, with the focus position selected by the selection module 21 为 as the center, the area of the focus range (W*H) is selected, and the sharpness of the area is calculated as the image. The clarity. Wherein, the precision focusing module 212 stores the calculated image sharpness in the array D (starting from D[〇]). The Z-axis coordinate of the CCD lens 32 is stored in the array z (starting from z[〇] )). The sharpness of the parent image and the Z-axis coordinate of the corresponding CCD lens 32 are the same in the index positions of the array D and the array z. For example, if the sharpness of the third image is stored in D[2] (index position is 2), the Z-axis coordinate of the CCD lens 32 corresponding to the third image is stored in z[2] (index position is 2). . In the present embodiment, if the number of elements of the arrays z and z is less than 7 ′, the focus failure information is returned. The data processing module 213 is configured to filter the image resolution calculated by the precise focus module 212 and the Z-axis coordinate of the corresponding ccd lens 32 根据 according to the mean filtering algorithm, and update the array D and the array with the filtered data. Z. In the present embodiment, filtering the image sharpness and the Z-axis coordinate of the corresponding CCD lens 32 means filtering the value of the image sharpness and the z-axis coordinate value corresponding to the CCD lens 32. Referring to Figure 4, there is shown a schematic diagram of the present invention for filtering image sharpness based on a mean filtering algorithm. In Figure 4a, array D stores the image sharpness before filtering, which is D[0] = 10 ' D[l] = 12 ' D[2] = 14, D[3] = 13, D[4] = 12, D[5] = 14 ' D[6] = 13, D[7] = 15, d[8] = 14. Array D1 in Figure 4b stores the filtered image clarity. According to the mean filtering algorithm 201027157, the new size of an element in array D = (the size of the first n elements of the element + the size of the element + the size of the η elements after the element) / (the total number of elements participating in the calculation) ), where the first element and the last element are the same size. In the present embodiment, taking π=1 'the new size of an element in the array = = (the size of the element before the element + the size of the element + the size of the element after the element) / 3, thereby knowing ,di[1] = (D[0] + D[l] + D[2])/3=12, Dl[2] = (D[l] + D[2] + D[3])/3 = 13, Dl[3]= ❹(D[2] + D[3] + D[4])/3=13.·.. and so on, you can calculate 〇1[4]= 13 ' Dl[ 5] = 13, Dl[6] = 14 ' Dl[7] = 14, D1[0] and Dl[8] are the same size, ie D1[0] = D[0], Dl[8] = D[ 8]. Then, the data of the array D is updated with the data of the array D1. Similarly, according to the mean filtering algorithm, the Z-axis coordinate of the CCD lens 32 can be filtered, and the specific process is filtered with the image sharpness. The data processing module 213 is also used for the Z-axis coordinate of the filtered CCD lens 32. Perform equidistant refinement to get new Z-axis coordinates and new shadow & image clarity and update array D and array Z with new data. As shown in Fig. 5, the present invention is a schematic diagram of isometric refinement of the Z-axis coordinate of the CCD lens 32. In the coordinate system Z-D, the horizontal axis Z represents the Z-axis coordinate of the CCD head 32, and the vertical axis D represents image sharpness. The isometric refinement means that on the Z axis, starting from the first coordinate, taking a new z value at a certain distance, a new z-axis coordinate is obtained, which is recorded as an array Z2; then, according to the new The Z-axis coordinates calculate the new image definition, which is recorded as array D2. Finally, the data of array Z is updated with the data of array Z2, and the data of array D is updated with the data of array D2. For example, the 7th new 201027157 'Z-axis coordinate Z2[6] corresponds to the new image definition D2[6]. The calculation process is: first find Z[i] from the array Z, so that Z[i]SZ2 [6] and Z[i+l]2Z2[6], which is Z[7] (Z[7]<Z2[6] and Z[8]>Z2[6]) in Fig. 5; The connecting points (Z[7], D[7]) and (Z[8], D[8]) get a straight line, and calculate the intersection of the straight line and the straight line z=Z2[6]. The ordinate of the intersection point is The value of D2[6]. The precision focus module 212 is also used to calculate an accurate focus position based on the selected focus surface, the new Z-axis coordinate, and the new image sharpness, and to move the CCD lens 32 to the precise focus position. Among them, the process of calculating the precise focus position is as follows. First, the precision focusing module 212 selects the maximum value Dmax from the array D. In the present embodiment, 'Dmax is greater than 3, and if Dmax is less than or equal to 3, the focus failure information is returned. Then, a local maximum point Df greater than Dmax/3 and greater than 3 is searched in the array D in reverse or sequentially according to the selected focus surface, and the corresponding index position is lndexf. Specifically, if the selected focus surface is the upper surface, a series of local maximum point Df greater than Dmax/3 and greater than 3 is searched in reverse in array D; if the selected focus surface is the lower surface, then array D The middle search sequentially searches for a local maximum point Df greater than Dmax/3 and greater than 3. The local maximum point means that the value of the point is greater than or equal to the value of the first m pieces of data and the value of the last m pieces of data. In the present embodiment, m=2 is taken. The precise focus module 212 further searches the array D in reverse/sequentially with lndexf as the center to obtain the local minimum points DminL and DminR, and the corresponding index positions are IndexL and IndexR, respectively. The local minimum point means that the value of the point is less than or equal to the value of the first m pieces of data and the value of the last m pieces of data, 11 201027157 in the presently known mode, taking m=2. If DminL<DminR, then search for array D in the reverse order from Indexf until D[i]>DminR, D[il]<DminR ends searching 'where IndexL=i; if Dmini^DminR, then Indexf is Center, sequentially searches the array 〇 until D[i]>DminR, D[i+l]<DminR, and ends the search, where IndexR=i. Then the precision focusing module 212 connects the point between IndexL and IndexR in the Z-D coordinate system, and the point indexL is connected with the point indexR.

0 becomes the closed area CR (see Fig. 6), and the midZ is made such that the straight line z=midZ bisects the closed area CR, which is the precise focus position. Referring to Figure 7, the present invention calculates a schematic diagram of the closed region CR bisector z = midZ. Wherein, the closed region cr is composed of triangles Tril and Tri2, trapezoidal Tral, Tra2...Tra(n), and the total area of the closed region CR is: Area-A = Tril + Tral + Tra2 + ... + Tra(n) + Tri2. Let i=l to n and substitute the formulas one by one: Area-L(i)=Tril+Tral+Tra2 ❹ + ...+Tra(i) ' When Area-L(i)$Area-A/2 and Area-L( When i+l)>Area-A/2, the substitution is stopped, and f=i, l=il, r=i+l. Therefore, the area of the closed region CR to the left of the trapezoidal Tra(f): Area-L(l) = Tril + Tral + Tra2 + ... Tra(l); and the area of the closed region CR to the right of the trapezoid Tra(f):

Area-R(r) = Tri2 + Tra(r) + Tra(r+1) + ... + Tra(n). And: Area-L(l) + Area-R(r) + Tra(f) = Area-A, Area-L(l) < Area-R(r) + Tra(f),

Area-R(r) < Area-L(l) + Tra(f). 12 201027157 The straight line z=midZ that divides the closed region CR passes through the trapezoidal Tra(f), according to the point (Z[f], D[f]) and the point (Z[f+1], D[f+1]) The straight line y = k*x+b, therefore, (1) (2) (3) midD = k*midZ + b • The trapezoidal Tra(f) is on the left side of the line z=midZ Area: ' AL = (midD+D[ f])*(midZ-Z[f])/2 Trapezoidal Tra(f) on the straight line z=midZ right area: AR= (midD+D[f+l])*(Z[f+l]-midZ) /2 Closed area The area to the left of the CR bisector is equal to the area on the right: Area-L(l)+AL = Area-R(r) + AR (4) Substituting equation (1) into equations (2) and (3), Substituting (2) and (3) into (4) yields: Area-L(l)+(k*midZ+b+D[f])* (midZ-Z[f])/2= Area-R( r) +(k*midZ+b+D[f+l])*(z[f+l]-midZ)/2, only one unknown midZ, solve the equation to find midZ, so that z=midZ is evenly closed Area CR. Referring to Figure 8, there is shown a flow chart of a preferred embodiment of the multi-surface focusing method of the present invention. First, in step S40, the focus surface, the focus position, and the focus $2* are selected by the selection module 21 〇 in the image of the workpiece 35 to be tested taken by the image measuring machine 3. In the present embodiment, the in-focus surface includes the upper surface and the lower surface of the workpiece 35 to be tested, and the focusing range has a length w and a width of Η. In step S41, the coarse focus module 211 controls the CCD lens 32 to move to find a rough focus position, as described above. Step S42 'The precise focus module 212 controls the CCD lens 32 to move from bottom to top in the z-axis direction within the set precise distance centering on the rough focus position of the 13 201027157, and continuously intercepts the image and CCD of the workpiece 35 to be tested. The Z-axis coordinate of the lens 32.

In step S43, the precise focus module 211 selects the image of the workpiece 35 to be tested for each of the images to be measured, selects the focus position selected by the module 21, and selects the area of the focus range (W*H) to calculate the area. The sharpness is used as the sharpness of the image. Wherein, the precision focusing module 212 stores the calculated t/image resolution in the array D (starting from D[〇]), and the Z-axis coordinate of the CCD lens 2 is stored in the array z (starting from z[〇]) The resolution of each image and the z-axis coordinate of the corresponding CCD lens 32 are the same in the index positions of the array D and the array Z. In the present embodiment, 'if the number of elements of the arrays D and z is less than 7, the focus failure information is returned. Step S44' The data processing module 213 filters the image resolution calculated by the correct focus module 212 and the Z-axis coordinate of the corresponding cCD lens 32 according to the mean filtering algorithm, and updates the array 阵列 and the array Z with the filtered data. . See the description of Figure 4 for the specific process. Step S45' The data processing module 213 performs equidistant refinement on the filtered CCD lens 32=z-axis coordinates to obtain a new z-axis coordinate and a new image β-degree 'and update the array D and the array with new data. . The specific process is described in the description of FIG. Step S46' precision focus module 212 calculates an accurate focus position based on the selected focus surface, the new Z-axis coordinate, and the new image sharpness. Among them, the process of calculating the precise focus position is shown in FIG. 9. Step S47' The precision focus module 212 moves the CCD lens 32 to the precise focus position of 201027157. Referring to Fig. 9, there is shown a specific flow chart for calculating the precise focus position in step S46 of the present invention. In step S50, the precision focusing module 212 selects the maximum value Dmax' from the array D. In the present embodiment, if the Dmax is smaller than the dream 3', the focus failure information is directly returned. Step S51, searching for a local maximum value point Df greater than Dmax/3 and greater than 3 in reverse or sequential order in the array D according to the selected focusing surface, and the index position of the corresponding index is Indexf. Specifically, if the selected focus surface is the upper surface, a local maximum value point Df greater than Dmax/3 and greater than 3 is reversely searched in the array D; if the selected focus surface is the lower surface, the order is in the array D Search for a local maximum point Df greater than Dmax/3 and greater than 3. The local maximum point means that the value of the point is greater than or equal to the value of the first m pieces of data and the value of the last piece of data. In the present embodiment, m=2. In step S52, the precise focus module 212 takes the indexf as the center, and searches the array D for the local minimum value points DminL and DminR respectively, and the corresponding index positions are IndexL and IndexR, respectively. The local minimum point means that the value of the point is less than or equal to the value of the first m pieces of data, and in the present embodiment, m=2. In step S53, the precision focusing module 212 determines whether DminL is less than DmmR. If DminL is less than DminR, step S54 is performed, if

DminL is greater than or equal to DminR, and step S55 is performed. In step S54, the precision focusing module 212 centers on the indexf, searches the array D in reverse order until D[i]>DminR, D[M]<DminR, and ends the search, 15 201027157, where IndexL=i, and then performs step S56. In step S55, the precision focusing module 212 searches for the array D until D[i]>DminR, D[i+l]<DminR, and searches for the index 'R in the order of Indexf, and then performs step S56. In step S56, the precision focusing module 212 connects the point between IndexL and IndexR in the ZD coordinate system as shown in FIG. 6, and connects the point IndexL and the point IndexR to form a closed region CR, and finds the midZ such that the line Az =midZ divides the closed area CR equally. The calculation of the closed area CR flat line is not described with reference to the description in Fig. 7, and will not be described here. In step S57, the precise focus module 212 uses the focus position midZ as the precise focus position. It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and the present invention is not limited thereto. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that Modifications or equivalent substitutions are made without departing from the spirit and scope of the invention. For example, apply this method to find boundary points on a clear boundary line. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a system architecture diagram of a preferred embodiment of a multiple surface focusing system of the present invention. Fig. 2 is a schematic structural view of an image measuring machine. Figure 3 is a schematic illustration of the calculation of image sharpness in accordance with the present invention. Fig. 4 is a schematic diagram showing the image clarity of the image according to the mean filtering algorithm of the present invention. 16 201027157 FIG. 5 is a schematic diagram showing the equidistance refinement of the Z-axis coordinate of the CCD lens according to the present invention. Figure 6 is a schematic illustration of the closed region CR of the present invention. Figure 7 is a schematic illustration of the calculation of the closed region CR bisector in accordance with the present invention. Figure 8 is a flow diagram of a preferred embodiment of the multiple surface focusing method of the present invention. Figure 9 is a detailed flow chart for calculating the precise focus position in the step of Figure 8.

[Main component symbol description] Display device 1 Host 2 Image measuring machine 3 Input device 4 Storage body 20 Surface focusing unit 21 Focus data 22 Selection module 210 Rough focus module 211 Precision focusing module 212 Data processing module 213 Selection Focus surface, focus position and focus range S40 Control CCD lens movement to find rough focus position S41 Move the CCD lens within the set distance and continuously capture the image of the workpiece to be tested and the Z-axis coordinate S42 S43 of the CCD lens in the focus range Sharpness of each image 17 201027157

Filter the image sharpness and the Z-axis coordinate of the CCD lens. S44 Perform the equidistant refinement of the Z-axis coordinate of the CCD lens to obtain a new Z « axis coordinate and new image sharpness S45. According to the selected focus surface, the new Z Axis coordinates and new image clarity " Degrees calculate the exact focus position S46 ' Move the CCD lens to the precise focus position S47

〇 18

Claims (1)

201027157 VII. Patent Application 1 · A multi-surface focusing method, the method includes the following steps: selecting a focus table*, a focus position, and a focus range in an image of a workpiece to be tested captured by the image measuring machine; The CCD lens of the measuring machine moves to find the rough focus position, and the control CCD lens is centered on the rough focus position, moves from bottom to top along the Z-axis direction within the set precise distance, and continuously intercepts the workpiece to be tested. The image and the Z-axis coordinate of the CCD lens; for each image of the workpiece to be measured, centering on the selected focus position, selecting the area of the focus range, and calculating the sharpness of the area as the image clarity Degree; according to the mean filtering algorithm, the image sharpness and the Z-axis coordinate of the corresponding CCD lens are filtered; the Z-axis coordinates of the filtered CCD lens are equidistantly refined to obtain the new Z-axis coordinate and the new image clarity. Degree; calculate the exact focus position based on the selected focus surface, the new Z-axis coordinate and the new image sharpness; and the CCD mirror Move accurate focus position. 2. The multiple surface focusing method of claim 1, wherein the focusing surface comprises an upper surface and a lower surface of the workpiece to be tested. 3. The multi-surface focusing method according to claim 1, wherein the image of the workpiece to be tested and the Z-axis coordinate of the corresponding CCD lens are stored in the array D and the array Z, respectively, and the definition of each image And the Z-axis coordinates of the corresponding 19 201027157 CCD lens are the same in the index positions of array D and array Z. The multi-surface focusing method described in item 3 of the towel/patent model, the method of filtering the sentence value refers to: array D or array Z - the new size of the alizarin = (the element 胄 n elements The size of the element + the size of the element + the back of the 11 elements of the element (the total number of elements involved in the calculation ♦), where 'the first element and the last element size are unchanged. ❹ 5 * towel 1 patent _ 3 The multi-surface focusing method described in the above, wherein the equidistant refinement means that the coordinate system ZD is established by the array Ζ and the array D, the Ζ axis coordinates of the CCD lens, and the vertical axis d represents the image sharpness. On the axis, starting from the first coordinate, taking a new threshold value at a certain distance, that is, obtaining a new 2-axis coordinate. For example, the multi-surface focusing method described in the fifth aspect of the patent scope, wherein the step is accurately calculated The focus position includes: , selecting a maximum value Dmax from the array D, and D_ is greater than 3; 搜索 searching for a local maximum value greater than Dmax/3 and greater than 3 in reverse or sequentially in the array D according to the selected focusing surface, corresponding to The index position is Indexf; with Indexf as the center, respectively /The sequential search array D obtains the local minimum value points DminL and DminR 'the corresponding index positions are IndexL and IndexR respectively; if DminL<DminR, the index D is searched in the reverse order, until D[i]>DminR,D [il]<DminR ends the search, where IndexL=i, if Dminl^DminR, then Ifldexf is centered, and Array 20 is searched for the order of D[i]>DminR, D[i+l] <DminR ends the search 'where IndexR=i; and in the ZD coordinate system, the point between IndexL and IndexR is connected, the point IndexL is connected with the point in (jexR, forming a closed region cr, and the midZ is a straight line z=midZ bisects the closed region CR, which is the precise focus position. 7 · The multiple surface focusing method according to the scope of the patent application, wherein the selected focusing surface is The step of searching for a local maximum point Df greater than Dmax/3 and greater than 3 in the array D in reverse order or sequentially includes the following steps: If the selected focus surface is the upper surface, the reverse search in array D is greater than Dmax/3 and greater than Partial maximum of 3 Value point Df; and if the selected focus surface is the lower surface, sequentially search for a local maximum point Df greater than Dmax/3 and greater than 3 in array D. Multi-surface focusing system, including host and image measuring machine Taiwan, ® wherein the host includes: a selection module 'for selecting a focus surface, a focus position, and a focus range in an image of a workpiece to be tested taken by the image measuring machine; a focusing module for controlling the image The CCD lens of the measuring machine moves to find a rough focus position; the precise focusing module is used to control the CCD lens to move from bottom to top along the z-axis direction within a set precise distance centering on the rough focus position, and Continuously intercept the image of the workpiece to be tested and the z-axis coordinate of the cCD lens; 21 201027157 The precise focus module 'is also used to calculate the sharpness of the area as the image data processing module' for the Z-axis coordinates of the corresponding CCD lens according to the mean filtering algorithm. 1; The data processing module of the Z-axis of the lens is also used for isometric refinement of the filtered axis coordinate and the new image clear coordinate to obtain a new z-axis coordinate and each degree; and the precise focus The module is also used to calculate the exact focus position based on the selected focus surface, the new z-axis coordinate, and the new image sharpness to move the CCD lens to the precise focus position. 9. The multiple surface focusing system of claim 8, wherein the focusing surface comprises an upper surface and a lower surface of the workpiece to be tested. The multi-surface focusing system of claim 8, wherein the image of the workpiece to be tested and the coordinate of the corresponding CCD lens are stored in the array D and the array, each of the images. The sharpness and the axis coordinates of the corresponding CCD lens are the same at the index positions in array D and array 。. twenty two