Segmented multipole focusing axis coaxiality detection method and coaxiality detection device

Abstract

The present invention provides a method for detecting the coaxiality of a segmented multipole focusing axis, comprising: S1, obtaining the field circle center A at the entrance end of the multipole structure; n The coordinates (X An ,Y An ,Z An ) and the center of the field circle B at the exit n The coordinates (X Bn ,Y Bn ,Z Bn );A n represents the center of the field circle at the entrance of the nth multipole structure, B n represents the field circle center of the outlet end of the n-th multipole structure; S2, according to (X An ,Y An ,Z An )、(X Bn ,Y Bn ,Z Bn ) determine the focusing axis equation of the multipole structure; S3, according to the focusing axis equations of the two adjacent multipole structures, construct the minimum cylinder that can envelop the axis of the rear multipole structure with the axis of the front multipole structure as the center line, and obtain the diameter d of the cylinder n,n+1 ; S4, obtain the focusing axis coaxiality d0 = max{d n,n+1 The focusing axis equation is: #imgabs0# The present invention also provides a coaxiality detection device. This device replaces the traditional method of calculating coaxiality by measuring the height and horizontal distance of multipoles. It can be applied to both parallel and tilted multipoles, and has a wide range of applications and a simple method.

Description

Technical Field

[0001] The present invention relates to the field of thin film technology, and in particular to a method and a device for detecting the coaxiality of a segmented multipole focusing axis. Background Art

[0002] Mass spectrometers have become indispensable tools in organic chemistry, pharmacology, biochemistry, medicine, toxicology, food chemistry, forensics, petrochemistry, geochemistry, pollution studies, and many other fields. Ion optics is one of the core technologies in mass spectrometry. Ion lenses in ion optics use electrodes and magnetic poles to create a specific electromagnetic field, thereby refracting, deflecting, and focusing the ion beam.

[0003] High-end mass spectrometers typically incorporate a multi-segment ion lens system. For example, a triple quadrupole mass spectrometer typically features at least four lens segments: Q0, Q1, Q2, and Q3. Most mass spectrometers also incorporate a pre-quadrupole lens, adding to the number of lenses. Most ion lenses are quadrupole or multipole structures, and their performance is similar to that of optical lenses, with a single ion focusing axis, also known as the ion optical axis. The ion transmission efficiency of the entire ion optical system is largely influenced by the relative positions of the focusing axes at the exit and entrance of the various ion lens segments. The focusing axis at the exit of one segment should be as coaxial as possible with the focusing axis of the next segment. Typically, the ion optical axis coaxiality of a triple quadrupole mass spectrometer should reach 0.2 mm.

[0004] However, the ion optical axis is actually a virtual axis, and there is no external rotating body contour to measure. Regarding measuring the coaxiality of the ion focusing axis, our patent CN209216909U proposes a method for calculating the center of the field circle based on the outer dimensions of the quadrupole. However, this method has some limitations. It cannot measure tilted multipoles, such as the LINAC-I collision cell quadrupole from AB SCIEX in the United States or the 3Q series collision cell quadrupole from IONICS in Canada. For tilted multipoles, the height and horizontal distance of the poles cannot be measured. Only the outer contour position of the fixed pole base can be measured, which may result in errors caused by the field circle formed by the multipole and the fixed base not being concentric. Summary of the Invention

[0005] In order to achieve the above objectives, the present invention is implemented through the following technical solutions.

[0006] The present invention provides a method for detecting the coaxiality of a segmented multipole focusing axis, comprising:

[0007] S1. Obtain the field circle center A at the entrance end of the multipole structure n The coordinates (X An ,Y An ,Z An) and the center of the field circle B at the exit n The coordinates (X Bn ,Y Bn ,Z Bn );A n represents the center of the field circle at the entrance of the nth multipole structure, B n represents the center of the field circle at the exit end of the nth multipole structure;

[0008] S2, according to (X An ,Y An ,Z An )、(X Bn ,Y Bn ,Z Bn ) Determine the focusing axis equation of the multipole structure;

[0009] S3. Based on the focusing axis equations of the two adjacent multipole structures, a minimum cylinder that can envelop the axis of the subsequent multipole structure is constructed with the axis of the preceding multipole structure as the center line, and the diameter d of the cylinder is obtained. n,n+1 ;

[0010] S4. Obtain the focusing axis coaxiality of the segmented multipole d0 = max{d n,n+1};

[0011] Wherein, the focal axis equation is:

[0012]

[0013] Preferably, step S1 includes:

[0014] S11, placing the multipole structure on a three-coordinate measuring instrument, setting a first reference plane at the entrance end of the multipole structure, the first reference plane offsetting the entrance end face of each pole of the multipole structure; obtaining the intersection point A of the axis of each pole and the first reference plane by the three-coordinate measuring instrument n,i Coordinates A n,i represents the intersection of the axis of the i-th rod of the n-th multipole structure on the first reference plane;

[0015] S12, setting a second reference plane at the outlet end of the multipole structure, the second reference plane offsetting the outlet end face of each pole of the multipole structure; obtaining the intersection point B of the axis of each pole and the second reference plane by a three-coordinate measuring instrument n,i Coordinates B n,i : represents the intersection point of the axis of the i-th rod of the n-th multipole structure on the second reference plane;

[0016] S13, calculate and obtain coordinates (X An ,Y An,Z An ), coordinates (X Bn ,Y Bn ,Z Bn ); the calculation formula is:

[0017]

[0018]

[0019] Wherein, k represents the number of rods in the multipole structure, in pieces.

[0020] Preferably, step S11 further comprises: contacting a first plane plate at the inlet end of the multipole structure, obtaining at least three points of the first plane plate using a three-coordinate measuring machine, and obtaining a first reference plane by fitting using a least square method.

[0021] Preferably, step S12 further comprises: contacting a second plane plate at the outlet end of the multipole structure, obtaining at least three points of the second plane plate using a three-coordinate measuring machine, and obtaining a second reference plane by least squares fitting.

[0022] Preferably, the method further comprises the steps of:

[0023] A three-coordinate measuring instrument is used to obtain the local outer contour point cloud of the entrance section, middle section and exit section of each pole of the multipole structure, and the axis of each pole is obtained by fitting using the least squares method.

[0024] Preferably, the outer contour point cloud of one quarter to one third of the circumference of the entrance section, middle section and exit section of each pole is obtained.

[0025] Preferably, outer contour point clouds of cylindrical segments with axial lengths greater than or equal to 5 mm are obtained for the inlet segment, the middle segment, and the outlet segment, respectively.

[0026] The present invention also provides a coaxiality detection device for executing the above-mentioned segmented multipole focusing axis coaxiality detection method, which comprises:

[0027] Coordinate measuring machine, used to fix several multipole structures and perform measurements;

[0028] At least one planar plate, configured to abut against the inlet end or the outlet end of the multipole structure;

[0029] Control module, used for control and calculation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides a method for detecting the coaxiality of a segmented multipole focusing axis. The method determines the focusing axis equation of the multipole structure by obtaining the field circle centers at the inlet and outlet ends of the multipole structure. After the focusing axis equations of two adjacent multipole structures are determined, a minimum cylinder that can envelop the axis of the subsequent multipole is constructed with the axis of the preceding multipole as the center line, and the diameter d of the cylinder is obtained. n,n+1 , obtain the d of each group of adjacent multipole structures n,n+1 The maximum value is taken to determine the coaxiality of the segmented multipole's focusing axis. This method replaces the traditional method of calculating coaxiality by measuring the height and horizontal distance of the multipole. It can be applied to both parallel and tilted multipoles, with a wide range of applications and a simple method.

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the description, the following preferred embodiments of the present invention are described in detail with reference to the accompanying drawings. The specific implementation methods of the present invention are given in detail by the following embodiments and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 is a flow chart of the steps of the coaxiality detection method of the present invention;

[0035] Figure 2 It is a schematic diagram of the partial structure of the device body of the present invention;

[0036] Figure 3 A schematic diagram of the principle of the three-coordinate measuring probe of the present invention measuring the circumferential outer contour point cloud of each pole of the first multipole structure;

[0037] Figure 4 Schematic diagram of the outer contour point cloud detection of the entrance section, middle section and exit section of the first multipole structure of the present invention;

[0038] Figure 5 Schematic diagram of the intersection of the axes on the first reference plane when the first multipole structure of the present invention is a quadrupole structure;

[0039] Figure 6 Schematic diagram of the coaxiality calculation principle of the first multipole structure and the second multipole structure of the present invention;

[0040] Figure 7 is a side view of the parallel quadrupole structure of the present invention;

[0041] Figure 8It is a side view of the tilted quadrupole structure of the present invention.

[0042] In the picture:

[0043] 10. Device body; 11. Three-coordinate measuring instrument; 111. Ion optical guide rail; 112. Three-coordinate measuring head; 12. Plane plate; 131. First multipole structure; 132. Second multipole structure. DETAILED DESCRIPTION

[0044] The present invention will be described in further detail below in conjunction with the accompanying drawings. The above-mentioned and other purposes, features, aspects and advantages of the present invention will become more apparent so that those skilled in the art can implement them with reference to the text of the specification. In the accompanying drawings, for the sake of clarity, shapes and sizes may be exaggerated, and the same reference numerals will be used in all figures to indicate the same or similar parts. In the following description, words such as center, thickness, height, length, front, back, rear, left, right, top, bottom, top, bottom, etc. are based on the orientation or positional relationship shown in the accompanying drawings. In particular, "height" is equivalent to the size from top to bottom, "width" is equivalent to the size from left to right, and "depth" is equivalent to the size from front to back. These relative terms are for the sake of convenience of explanation and are generally not intended to require a specific orientation. Terms related to attachment, connection, etc. (e.g., "connection" and "attachment") refer to the relationship between these structures that are directly or indirectly fixed or attached to each other through an intermediate structure, as well as movable or rigid attachment or relationship, unless otherwise explicitly stated.

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0046] Example 1

[0047] The present invention provides a method for detecting the coaxiality of a segmented multipole focusing axis. Figure 1 Shown, including:

[0048] S1. Obtain the field circle center A at the entrance end of the multipole structure n The coordinates (X An ,Y An ,Z An ) and the center of the field circle B at the exit n The coordinates (X Bn ,Y Bn ,Z Bn );A n represents the center of the field circle at the entrance of the nth multipole structure, B n represents the center of the field circle at the exit end of the nth multipole structure;

[0049] S2, according to (X An ,Y An ,Z An )、(X Bn ,Y Bn ,Z Bn ) Determine the focusing axis equation of the multipole structure;

[0050] S3. Based on the focusing axis equations of the two adjacent multipole structures, a minimum cylinder that can envelop the axis of the subsequent multipole structure is constructed with the axis of the preceding multipole structure as the center line, and the diameter d of the cylinder is obtained. n,n+1 ;

[0051] S4. Obtain the focusing axis coaxiality of the segmented multipole d0 = max{d n,n+1};

[0052] Wherein, the focal axis equation is:

[0053]

[0054] In this embodiment, the center of the field circle at the inlet and outlet of the multipole structure is obtained to determine the focusing axis equation of the multipole structure. After the focusing axis equations of the two adjacent multipole structures are determined, the minimum cylinder that can envelop the axis of the subsequent multipole structure is constructed with the axis of the preceding multipole structure as the center line, and the diameter d of the cylinder is obtained. n,n+1 , obtain the d of each group of adjacent multipole structures n,n+1 Since ion transmission is continuous, the assembly position of each multipole segment only affects the transmission efficiency of the ion lenses before and after it. Therefore, it is sufficient to evaluate the coaxiality between two adjacent multipole segments, and the maximum value is taken to determine the coaxiality of the segmented multipole's focusing axis. This method replaces the traditional method of calculating coaxiality by measuring the height and horizontal distance of the multipole. It can be applied to parallel and tilted multipoles, with a wide range of applications and a simple method. The field circle is a circle tangent to each rod of the multipole structure and is used to characterize the electromagnetic field region formed in the center of the multipole structure.

[0055] Specifically, the coaxiality between the first multipole structure and the second multipole structure is taken as an example for detailed description. For the first multipole structure, the coordinate (X A1 ,Y A1 ,Z A1 )、(X B1 ,Y B1 ,Z B1 ), and then determine the focusing axis equation of the first multipole structure as For the second multipole structure, obtain the coordinates (X A2 ,Y A2 ,ZA2 )、(X B2 ,Y B2 ,Z B2 ), and then determine the focusing axis equation of the first multipole structure as According to the two focusing axis equations, the minimum cylinder that can envelop the axis of the subsequent multipole structure is constructed with the axis of the previous multipole structure as the center line, and the diameter d of the cylinder is obtained. 1,2 .

[0056] Similarly, when obtaining the coaxiality between the second multipole structure and the third multipole structure, by obtaining (X A2 ,Y A2 ,Z A2 )、(X B2 ,Y B2 ,Z B2 )、(X A3 ,Y A3 ,Z A3 )、(X B3 ,Y B3 ,Z B3 ), determine the focusing axis equation of the second multipole structure and the focusing axis equation of the third multipole structure, construct the minimum cylinder that can envelop the axis of the third multipole structure with the axis of the second multipole structure as the center line, and finally obtain d 2,3 , which represents the coaxiality between the second and third multipole structures. The coaxiality between each set of adjacent multipole structures is obtained using the same method, and the maximum coaxiality is taken to represent the coaxiality of the segmented multipole.

[0057] Taking the quadrupole lens as an example, it includes four multipole structures, and the d 1,2 d 2,3 d 3,4 , take the maximum value among the three as the coaxiality of the focusing axis of the quadrupole lens.

[0058] In one embodiment, step S1 includes:

[0059] S11, placing the multipole structure on a three-coordinate measuring instrument, setting a first reference plane at the entrance end of the multipole structure, the first reference plane offsetting the entrance end face of each pole of the multipole structure; obtaining the intersection point A of the axis of each pole and the first reference plane by the three-coordinate measuring instrument n,i Coordinates A n,i represents the intersection of the axis of the i-th rod of the n-th multipole structure on the first reference plane;

[0060] S12, setting a second reference plane at the outlet end of the multipole structure, the second reference plane offsetting the outlet end face of each pole of the multipole structure; obtaining the intersection point B of the axis of each pole and the second reference plane by a three-coordinate measuring instrument n,i Coordinates B n,i : represents the intersection point of the axis of the i-th rod of the n-th multipole structure on the second reference plane;

[0061] S13, calculate and obtain coordinates (X An ,Y An ,Z An ), coordinates (X Bn ,Y Bn ,Z Bn ); the calculation formula is:

[0062]

[0063]

[0064] Wherein, k represents the number of rods in the multipole structure, in pieces.

[0065] Specifically, corresponding reference surfaces are set at the inlet and outlet ends of the multipole structure to form an intersection A. n,i , intersection B n,i , finally calculate the coordinates (X An ,Y An ,Z An ), coordinates (X Bn ,Y Bn ,Z Bn ), easy to operate and calculate. Take the triple quadrupole lens as an example for specific explanation, n = 1, 2, 3; i = 1, 2, 3, 4; k = 4. Take the first quadrupole structure as an example for explanation, n = 1, such as Figure 5 As shown, the axes of the four poles form four intersection points A on the first reference plane. 1,1 、A 1,2 、A 1,3 、A 1,4 , forming four intersection points B on the second reference surface 1,1 、B 1,2 、B 1,3 、B 1,4 . A is obtained by three-coordinate measuring machine 1,1 、A 1,2 、A 1,3 、A 1,4 、B 1,1 、B 1,2 、B 1,3 、B 1,4 The coordinates of Add the values ​​and divide by 4 to get X A1 , and so on to get Y An , Z An 、X Bn 、Y Bn , Z Bn .

[0066] Furthermore, step S11 also includes: abutting the first plane plate at the entrance end of the multipole structure, using the three-coordinate side head 112 of the three-coordinate measuring instrument to obtain at least three points of the first plane plate, and fitting the first reference plane by the least squares method. The operation is simple and the measurement is simple. There is no need for guide rail leveling, and it is only necessary to ensure that there is no shaking during measurement.

[0067] Step S12 also includes: abutting the second plane plate at the outlet end of the multipole structure, using the three-coordinate side head 112 of the three-coordinate measuring instrument to obtain at least three points of the second plane plate, and fitting the second reference plane by the least squares method. The operation is simple and the measurement is simple. There is no need for guide rail leveling, and it is only necessary to ensure that there is no shaking during measurement.

[0068] Furthermore, the method further comprises the steps of:

[0069] like Figure 4 As shown, the three-coordinate side head 112 of the three-coordinate measuring instrument is used to obtain the local outer contour point cloud of the entrance section, middle section, and exit section of each pole of the multipole structure, and the axis of each pole is fitted by the least squares method. Instead of the scheme of measuring the height and horizontal distance of the multipole by transmission, the outer contour point cloud is directly detected and fitted to reduce the influence of the pole cylindricity error and the pole diameter error. It is applicable to parallel multipoles and tilted multipoles.

[0070] Further, if Figure 3 As shown, the outer contour point cloud of the entrance section, middle section, and exit section of each pole is obtained at one-quarter to one-third of the circumference to reduce the influence of the pole cylindricality error and the pole diameter error. Taking the quadrupole structure as an example, the quadrupole structure includes a first pole 141, a second pole 142, a third pole 143, and a fourth pole 144. Since the four structures are close to each other, it is difficult for the three-dimensional probe 112 to measure the outer contour point cloud of all the circumferences of each pole. Figure 3 As shown, the three-coordinate probe 112 is a point cloud of the outer contour of the portion of the quadrupole field channel formed by the first rod 141, the second rod 142, the third rod 143, and the fourth rod 144. The dotted arrow in Figure 3 indicates the measurement range of the three-coordinate probe 112.

[0071] Furthermore, the outer contour point clouds of the cylindrical segments with axial lengths greater than or equal to 5 mm are obtained for the inlet segment, the middle segment, and the outlet segment. Specifically, Figure 4As shown, taking the first multipole structure 131 as an example for specific explanation, the outer contour point clouds of the inlet section L1 with a length of 10 mm, the middle section L2 with a length of 10 mm, and the outlet section L3 with a length of 10 mm of the first multipole structure 131 are obtained.

[0072] In one embodiment, if Figure 6 As shown, the first multipole structure and the second multipole structure are used as examples for specific explanation. The field circle center A1 (X A1 ,Y A1 ,Z A1 )、B1(X B1 ,Y B1 ,Z B1 )、A2(X A2 ,Y A2 ,Z A2 )、B2(X B2 ,Y B2 ,Z B2 ), the line connecting points A1 and B1 forms the first axis, the line connecting points A2 and B2 forms the second axis, and a plane S perpendicular to the first axis is drawn with point A1. The plane equation is:

[0073] (X B1 -X A1 )(XX A1 )+(Y B1 -Y A1 )(YY A1 )+(Z B1 -Z A1 )(ZZ A1 )=0.

[0074] Project the second axis onto plane S and obtain A'2(X A’2 ,Y A’2 ,Z A’2 )、B'2(X B’2 ,Y B’2 ,Z B’2 ), with A1 as the center, make a minimum circle that can simultaneously envelop points A'2 and B'2. The diameter of the minimum circle is the coaxiality d of the first and second multipole structures. 1,2 , where d 1,2 The mathematical formula is:

[0075]

[0076] The calculation formula for the coordinate values ​​of points A'2 and B'2 based on the geometric relationship of the projection is as follows:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Example 2

[0084] The present invention provides a coaxiality detection device, such as Figure 2 As shown, the device body 10 is used to perform the segmented multipole focusing axis coaxiality detection method as described above, and the device body 10 includes:

[0085] A coordinate measuring machine 11 is used to fix a plurality of multipole structures and perform measurements; for example, it is used to fix a first multipole structure 131 and a second multipole structure 132;

[0086] At least one planar plate 12, for contacting the inlet end or the outlet end of the multipole structure;

[0087] Control module, used for control and calculation.

[0088] In this embodiment, the device body 10 has a simple structure and a simple measurement process, and is applicable to parallel multipole rods and tilted multipole rods, and has a wide range of applications. Figure 6 As shown, the tilted quadrupole structure is as follows Figure 7 shown.

[0089] In one embodiment, if Figure 2 As shown, there is only one plane plate 12, which is placed at the entrance or exit of the multipole structure being measured. After measuring the intersection coordinates at one end, the plane plate 12 is moved to the other end.

[0090] In another embodiment, there are three planar plates 12 , which are respectively placed at the inlet and outlet ends of two adjacent multipole structures. Both sides of the planar plate 12 located between the two adjacent multipole structures abut against the opposite end surfaces of the two adjacent multipole structures.

[0091] In another embodiment, the number of the planar panels 12 may be two, four or even more.

[0092] In one embodiment, the coordinate measuring instrument 11 is provided with an ion optical track 111, and the multipole structure is arranged on the ion optical track 111. During measurement, the ion optical track 111 does not need to be strictly positioned, and the reference plane and coordinate axis can be found.

[0093] The above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and the above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for detecting the coaxiality of a segmented multipole focusing axis, characterized in that: include: S1. Obtain the field circle center A at the entrance end of the multipole structure n The coordinates (X An ,Y An ,Z An ) and the center of the field circle B at the exit n The coordinates (X Bn ,Y Bn ,Z Bn );A n represents the center of the field circle at the entrance of the nth multipole structure, B n represents the center of the field circle at the exit end of the nth multipole structure; S2, according to (X An ,Y An ,Z An )、(X Bn ,Y Bn ,Z Bn ) Determine the focusing axis equation of the multipole structure; S3. According to the focusing axis equations of the two adjacent multipole structures, a minimum cylinder that can envelop the axis of the subsequent multipole structure is constructed with the axis of the preceding multipole structure as the center line, and the diameter d of the minimum cylinder is obtained. n,n+1 ; S4. Obtain the focusing axis coaxiality of the segmented multipole d0 = max{d n,n+1 }; Wherein, the focal axis equation is: Wherein, step S1 includes: S11, placing the multipole structure on a three-coordinate measuring instrument, setting a first reference plane at the entrance end of the multipole structure, the first reference plane offsetting the entrance end face of each pole of the multipole structure; obtaining the intersection point A of the axis of each pole and the first reference plane by the three-coordinate measuring instrument n,i Coordinates A n,i represents the intersection of the axis of the i-th rod of the n-th multipole structure on the first reference plane; S12, setting a second reference plane at the outlet end of the multipole structure, the second reference plane offsetting the outlet end face of each pole of the multipole structure; obtaining the intersection point B of the axis of each pole and the second reference plane by a three-coordinate measuring instrument n,i Coordinates B n,i : represents the intersection point of the axis of the i-th rod of the n-th multipole structure on the second reference plane; S13, calculate and obtain coordinates (X An ,Y An ,Z An ), coordinates (X Bn ,Y Bn ,Z Bn ); the calculation formula is: Wherein, k represents the number of rods in the multipole structure, in pieces.

2. The method for detecting the coaxiality of a segmented multipole focusing axis according to claim 1, wherein: Step S11 further includes: contacting a first plane plate at the entrance end of the multipole structure, obtaining at least three points of the first plane plate using a three-coordinate measuring machine, and obtaining a first reference plane by fitting using a least squares method.

3. The method for detecting the coaxiality of a segmented multipole focusing axis according to claim 1, wherein: Step S12 further includes: contacting a second plane plate at the outlet end of the multipole structure, obtaining at least three points of the second plane plate using a three-coordinate measuring machine, and obtaining a second reference plane by least squares fitting.

4. The method for detecting the coaxiality of a segmented multipole focusing axis according to claim 1, wherein: Also includes the steps: A three-coordinate measuring instrument is used to obtain the local outer contour point clouds of the entrance section, middle section and exit section of each pole of the multipole structure, and the axis of each pole is obtained by fitting using the least squares method.

5. The method for detecting the coaxiality of the segmented multipole focusing axis according to claim 4, wherein: Obtain the outer contour point cloud of one-quarter to one-third of the circumference of the entrance section, middle section, and exit section of each pole.

6. The method for detecting the coaxiality of a segmented multipole focusing axis according to claim 4, wherein: Obtain the outer contour point clouds of the cylindrical segments with axial lengths greater than or equal to 5 mm at the inlet segment, middle segment, and outlet segment respectively.

7. The coaxiality detection device is characterized in that: A method for detecting the coaxiality of a segmented multipole focusing axis according to any one of claims 1 to 6, comprising: Coordinate measuring machine, used to fix several multipole structures and perform measurements; At least one planar plate, configured to abut against the inlet end or the outlet end of the multipole structure; Control module, used for control and calculation.

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