CN115615354A - Calibration method and calibration device for measuring instrument - Google Patents

Abstract

The present disclosure describes a calibration method of a measuring instrument and a calibration apparatus thereof, including: placing a standard part with a cross pattern on a bearing platform; a first objective lens in the objective lenses is used as a working objective lens, the working objective lens is focused and aligned to the cross pattern, the position of the first objective lens in the first direction is used as a first position, and the position of the bearing platform in a preset plane is used as a second position; a second objective lens in the objective lenses is used as a working objective lens, the position of the second objective lens is adjusted to enable the second objective lens to be focused on the cross pattern, the position of the bearing platform is adjusted to enable the second objective lens to be aligned with the cross pattern, the position of the second objective lens in the first direction is used as a third position, and the position of the bearing platform in a preset plane is used as a fourth position; performing parfocal calibration on the working objective lens based on the first position and the third position; and concentrically aligning the working objective lens based on the second position and the fourth position.

Description

Calibration method and calibration device for measuring instrument

Technical Field

The present disclosure relates generally to the field of smart manufacturing equipment, and more particularly to a method and apparatus for calibrating a measurement instrument.

Background

With the continuous development of science and technology, more and more technical products are in the direction of pursuing precise development for improving quality, such as precision instruments and equipment like a confocal microscope. The confocal microscope is a novel instrument with high photosensitivity and high resolution, and performs mechanical scanning by using the principle that three points of a light source, an object to be measured and an objective lens are conjugated with each other to obtain the relative height of the object to be measured so as to reconstruct the three-dimensional shape of the object to be measured.

Like a common imaging instrument, the confocal microscope also needs to switch the objective lens according to different samples or observation requirements. In order to improve the measurement accuracy and the measurement efficiency of the confocal microscope, ideally, each objective lens needs to satisfy the parfocal design and the concentric design. If each objective lens meets the parfocal design and the concentric design, the object to be measured can still be observed in the center of the view field after the objective lenses are switched, and the object is clear.

However, due to production and manufacturing errors, after objective lenses with different magnifications are switched, it is difficult to keep the objective lenses in-focus and concentric, which may cause problems such as unclear object and/or object located at the edge of the field of view of the objective lenses during observation of the object to be measured, and even more, the object to be measured may not be observed due to the object to be measured being located outside the field of view of the objective lenses. Therefore, there is an urgent need for a solution that can still locate the object to be measured at the center of the field of view of the objective lens and clearly view the object when switching different objective lenses to measure the object to be measured.

Disclosure of Invention

The present disclosure has been made in view of the above-described state of the art, and an object thereof is to provide a calibration method capable of performing parfocal and concentric calibration of a working objective lens and further improving measurement efficiency and measurement accuracy of a measuring instrument.

To this end, a first aspect of the present disclosure provides a calibration method for a surveying instrument including a carrying platform movable in a preset plane and a plurality of objective lenses movable in a first direction perpendicular to the preset plane, the calibration method being used for calibrating a working objective lens when switching the objective lenses, including: placing a standard part with a cross pattern on the bearing platform; enabling a first objective lens in the objective lenses to be used as a working objective lens, enabling the working objective lens to be focused and aligned to the cross pattern, enabling the position of the first objective lens in the first direction to be used as a first position, and enabling the position of the bearing platform on the preset plane to be used as a second position; a second objective lens in the objective lenses is used as a working objective lens, the working objective lens is used for measuring the standard piece, the position of the second objective lens is adjusted so that the second objective lens is focused on the cross pattern, the position of the bearing platform is adjusted so that the second objective lens is aligned to the cross pattern, the position of the second objective lens in the first direction is used as a third position, and the position of the bearing platform on the preset plane is used as a fourth position; in the measuring process, when the working objective lens is switched between the first objective lens and the second objective lens, performing parfocal calibration on the working objective lens based on the first position and the third position; and concentrically calibrating the working objective lens based on the second position and the fourth position.

According to the calibration method disclosed by the disclosure, a first error for representing the alignment degree of the working objective lens and a second error for representing the concentricity can be obtained in advance based on the standard piece with the cross pattern, when the object to be measured is measured, after different objective lenses are switched to be the working objective lens, the measuring instrument can control the movement of the working objective lens in the first direction based on the first error obtained in advance to carry out alignment calibration on the working objective lens, and control the movement of the bearing platform in the second direction based on the second error obtained in advance and multiple groups of second errors to carry out concentric calibration on the working objective lens, so that the phenomenon that the working objective lens is out of alignment and/or out of concentricity can be reduced as far as possible, and further the measurement efficiency and the measurement precision can be improved in the process of measuring the object to be measured.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, the measuring instrument further includes a rotating section for switching the plurality of objective lenses, and the different objective lenses are switched as the working objective lenses by rotating the rotating section in a preset order. This enables switching between different objective lenses as the working objective lens.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, a difference between the first position and the third position is a first error, and the working objective lens is subjected to parfocal calibration based on the first error. In this case, the working objective lens can be subjected to parfocal calibration by obtaining the first position and the third position and based on a difference between the first position and the third position, and the measurement accuracy of the measuring instrument can be further improved.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, the measuring instrument further includes a first measuring element for obtaining the first position and the third position, and the first measuring element is a grating ruler. In this case, since the grating scale has a characteristic of high detection accuracy, the position information of the first position and the third position can be obtained more accurately to improve the measurement accuracy.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, a difference between the second position and the fourth position is made to be a second error, and the working objective lens is concentrically calibrated based on the second error. In this case, the measurement accuracy of the surveying instrument can be improved by obtaining the second position and the fourth position and performing concentric calibration of the working objective lens based on the difference between the second position and the fourth position.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, the carrying platform is configured to be movable along a second direction within the preset plane and movable along a third direction orthogonal to the second direction, the second error includes a first sub-error along the second direction and a second sub-error along the third direction, and the concentric calibration of the working objective lens is performed based on the first sub-error and the second sub-error. In this case, the standard component can be moved into the field of view of the working objective lens by moving the bearing platform in the second direction and the third direction, so that the working objective lens can be aligned with the cross pattern to obtain the fourth position, and then the working objective lens can be conveniently calibrated subsequently based on the difference between the second position and the fourth position.

In addition, in the calibration method according to the first aspect of the present disclosure, optionally, the measuring instrument further includes a second measuring element for obtaining the second position and the fourth position, and a displacement of the carrying platform moving from the second position to the fourth position is obtained by the second measuring element to obtain the first sub-error and the second sub-error. In this case, the position information of the second position and the fourth position can be obtained more accurately, and thus the first sub-error and the second sub-error can be obtained to facilitate subsequent concentric calibration of the working objective lens.

Further, in the calibration method according to the first aspect of the present disclosure, optionally, when the working objective lens focuses the cross pattern, the cross pattern is located at a focal plane of the working objective lens, and when the working objective lens aligns the cross pattern, an optical axis of the working objective lens passes through a center of the cross pattern. In this case, the imaging quality of the object to be measured can be improved to make the object to be measured imaged clearly, that is, the cross pattern can be clearly visible, and the cross pattern can be located at the center of the field of view of the work objective lens.

Furthermore, a second aspect of the present disclosure provides a calibration device of a surveying instrument, the surveying instrument including a bearing platform movable in a preset plane and a plurality of objective lenses movable in a first direction perpendicular to the preset plane, the calibration device including a recording module for recording a first position and a second position when a first objective lens measures a standard having a cross pattern, and for recording a third position and a fourth position when a second objective lens measures the standard having the cross pattern, the first position being a position of the first objective lens in the first direction when the first objective lens is focused on the cross pattern of the standard, the second position being a position of the bearing platform in the preset plane when the first objective lens is focused on the cross pattern of the standard, the third position being a position of the second objective lens in the first direction when the second objective lens is focused on the cross pattern of the standard, and the fourth position being a position of the bearing platform in the preset plane when the second objective lens is focused on the cross pattern; the processing module is configured to obtain a first error based on the first location and the third location and a second error based on the second location and the fourth location; the storage module is configured to store a plurality of sets of the first errors and a plurality of sets of the second errors, and the control module is configured to obtain the first errors and the second errors from the storage module based on the switching condition of the working objective lens when the measuring instrument switches the working objective lens, control the working objective lens to move in the first direction to make the plurality of objective lenses in parfocal based on the first errors, and control the carrying platform to move in the preset plane to make the plurality of objective lenses concentric based on the second errors. Under the condition, when the measuring instrument switches the working objective lens, the working objective lens can be automatically subjected to parfocal calibration and concentric calibration based on the first error and the second error which are obtained in advance, so that the object to be measured can still be positioned on the focal plane of the working objective lens after the working objective lens is switched and positioned at the visual center of the working objective lens, therefore, the measuring instrument can directly measure the object to be measured based on the switched working objective lens, and the measuring efficiency can be improved while the original measuring precision is maintained.

In addition, in the calibration apparatus according to the second aspect of the present disclosure, optionally, the calibration apparatus further includes a driving module in signal connection with the control module, where the driving module includes a first driving mechanism for driving the working objective lens to move in the first direction and a second driving mechanism for driving the carrying platform to move in the plane corresponding to the preset plane. In this case, when the surveying instrument switches the working objective lens, the first driving mechanism may drive the working objective lens to move from the first position to the third position based on a first error obtained by the control module to perform the parfocal calibration on the working objective lens, and the second driving mechanism may drive the carrying platform to move from the second position to the fourth position based on a second error obtained by the control module to perform the concentric calibration on the working objective lens.

According to the calibration method disclosed by the invention, the working objective lens can be subjected to parfocal and concentric calibration, so that the measurement efficiency and the measurement precision of the measuring instrument are improved.

Drawings

The disclosure will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

fig. 1 is a perspective view schematically illustrating a measuring instrument according to an example of the present disclosure.

Fig. 2 is a flow chart illustrating a calibration method according to an example of the present disclosure.

Fig. 3 is a schematic diagram illustrating a standard component to which examples of the present disclosure relate.

Fig. 4 is a schematic diagram illustrating a first position and a third position according to an example of the present disclosure.

Fig. 5 is a schematic diagram illustrating a fourth position according to an example of the present disclosure.

Fig. 6 is a schematic diagram illustrating a second position and a fourth position according to an example of the present disclosure.

Fig. 7 is a schematic view illustrating a rotation portion according to an example of the present disclosure.

Fig. 8 is a flowchart illustrating a measurement method according to an example of the present disclosure.

Fig. 9 is a block diagram showing a configuration of a calibration apparatus according to an example of the present disclosure.

Detailed Description

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and redundant description thereof is omitted. The drawings are schematic, and the proportions of the dimensions of the components and the shapes of the components may be different from the actual ones.

It is noted that the terms "comprises" and "comprising," and any variations thereof, in this disclosure, such that a process, method, system, article, or apparatus that comprises or has a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include or have other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In addition, the headings and the like referred to in the following description of the present disclosure are not intended to limit the content or scope of the present disclosure, but merely serve as a reminder for reading. Such a subtitle should neither be understood as a content for segmenting an article, nor should the content under the subtitle be limited to only the scope of the subtitle.

The present disclosure relates to a calibration method of a measuring instrument (hereinafter, may be simply referred to as a calibration method), which may be used to calibrate a plurality of objective lenses during measurement of an object to be measured by the measuring instrument, such as performing parfocal calibration, concentric calibration, and the like. The calibration method can help to calibrate the alignment power and the concentricity of each objective lens, and further can improve the measurement efficiency and the measurement precision of the measuring instrument.

The calibration method to which the present disclosure relates may also be referred to as, for example, a verification method, a calibration method, and the like. It is to be understood that the names are for the purpose of illustrating the present disclosure and should not be taken as limiting.

In some examples, a surveying instrument to which the present disclosure relates may include a load-bearing platform and a plurality of objective lenses. The bearing platform can be used for bearing an object to be tested. Multiple objective lenses can be used to perform scanning measurement on the object to be measured. In some examples, the measurement instrument may be an instrument for measuring the object to be measured to reconstruct a three-dimensional topography of the object to be measured, for example, the measurement instrument may be a white light interferometer, a confocal microscope, or the like. In other examples, the measuring instrument may be an instrument for measuring a two-dimensional size of an object to be measured or for observing the object to be measured, and may be, for example, a flash meter, an image measuring instrument, or a general multifunctional microscope. The present disclosure is not so limited and the measurement instrument may be any instrument that includes a movable load-bearing platform and a plurality of objective lenses.

Hereinafter, the present disclosure will be described in detail by taking a confocal microscope as an example of a measurement instrument. Fig. 1 is a perspective view schematically illustrating a measuring instrument 1 according to an example of the present disclosure.

As described above, the surveying instrument 1 according to the present disclosure may include the carrying platform 10 and the plurality of objective lenses 20 (see fig. 1). In some examples, the load-bearing platform 10 may move in a predetermined plane. In some examples, the plurality of objective lenses 20 may be moved in the first direction D1. The first direction D1 may be perpendicular to the predetermined plane. In this case, the object to be measured can be moved into the field of view of the objective lens by moving the carrying platform 10 in the first plane, and the objective lens can be focused on the object to be measured by moving the objective lens in the first direction D1, so that the object to be measured can be clearly seen, thereby measuring the object to be measured.

In some examples, the first direction D1 may be a vertical direction. In some examples, a spatial rectangular coordinate system as shown in fig. 1 may be established with a preset plane and the first direction D1.

In some examples, each of the plurality of objective lenses 20 may have a different magnification. Therefore, in the process of measuring the object to be measured, the objective lenses with different magnifications can be switched as required to measure different objects to be measured or each area to be measured of the same object to be measured so as to obtain more accurate measurement information.

However, in actual measurement, the objective lens may be switched to cause "defocus" and/or "decentration". The term "out-of-focus" refers to that the object to be measured is not located on the focal plane of the switched objective lens after the objective lens is switched, and therefore the imaging of the object to be measured is not clear. "decentration" means that the optical axes of the front and rear objective lenses are not coincident, so that the field of view of the objective lenses is changed, and the object to be measured does not appear in the field of view of the objective lenses under severe conditions, namely, the object to be measured appears outside the field of view of the objective lenses, so that the object to be measured cannot be measured. If the positions of the objective lens and the object to be measured are adjusted at this time, a lot of time is consumed in the adjusting process, so that the measuring efficiency is low, and a lot of errors may be introduced by multiple times of adjustment.

The calibration method provided by the present disclosure can be used for performing parfocal calibration and concentric calibration on the objective lens so as to improve the measurement efficiency and measurement accuracy of the measuring instrument 1 in the process of measuring the object to be measured.

Fig. 2 is a flow chart illustrating a calibration method according to an example of the present disclosure.

In some examples, the calibration methods to which the present disclosure relates may be used to calibrate a working objective lens when switching objective lenses. In some examples, a working objective lens refers to an objective lens being used to scan an object under test. For example, assuming that the measuring instrument 1 includes 3 objective lenses, namely an objective lens a, an objective lens b, and an objective lens c, when the objective lens a measures the object to be measured, the objective lens a is a working objective lens; when the object to be measured needs to be switched from the objective lens a to the objective lens b, the switched objective lens b is a working objective lens; when the object to be measured needs to be measured by switching the objective lens a to the objective lens c, the switched objective lens c is a working objective lens.

In the present disclosure, the calibration method may include placing the standard 2 on the carrying platform 10 (step S200), obtaining a first position P1 and a second position P2 (step S400), obtaining a third position P3 and a fourth position P4 (step S600), performing parfocal calibration on the working objective lens based on the first position P1 and the third position P3 (step S800), and performing concentric calibration on the working objective lens based on the second position P2 and the fourth position P4 (step S1000). Thus, measuring the object to be measured based on the calibrated work objective lens can improve the measurement efficiency and measurement accuracy of the measuring instrument 1 (see fig. 2).

Fig. 3 is a schematic diagram showing a standard 2 according to an example of the present disclosure.

At step S200, the standard 2 may be placed on the load-bearing platform 10.

In some examples, the standard 2 may be a flat plate with better flatness. In some examples, the standard 2 may be rectangular, circular, oval, irregular, or the like. In some examples, the center of the standard 2 may have a cross pattern (see fig. 3). In this case, the working objective can be adjusted according to the cross pattern of the standard 2 to focus the working objective in the cross pattern, and the carrier platform 10 can be adjusted according to the cross pattern to align the working objective in the cross pattern.

Fig. 4 is a schematic diagram illustrating a first position P1 and a third position P3 according to an example of the present disclosure. It should be noted that the standard 2 shown in fig. 3 is scaled down and the drawing of the objective lens is simplified in order to better illustrate the present disclosure. Fig. 4 (a) shows a schematic view of the first objective lens 21 focused on a cross pattern; fig. 4 (b) shows a schematic diagram when the second objective lens 22 is switched as the operating objective lens by the first objective lens 21; fig. 4 (c) shows a schematic diagram of the second objective lens 22 focused on a cross pattern; fig. 5 is a schematic diagram illustrating a second position P2 according to an example of the present disclosure. Fig. 6 is a schematic diagram illustrating the second position P2 and the fourth position P4 according to the example of the present disclosure. Fig. 5 and 6 are placed in the coordinate system XY as shown in order to better illustrate the variation of the second position P2 and the fourth position P4.

In step S400, a first position P1 and a second position P2 may be obtained.

In some examples, the first objective lens 21 of the plurality of objective lenses 20 may be made to be the working objective lens. In some examples, the first objective lens 21 may be any one of the plurality of objective lenses 20.

In some examples, the working objective lens may be brought into focus and aligned with the cross pattern. Wherein the working objective is focused on the cross pattern may mean that the cross pattern is located in the focal plane of the working objective. In other words, the cross pattern may be located in the focal plane of the working objective lens when the working objective lens focuses the cross pattern. In this case, the imaging quality of the object to be measured can be improved to make the object to be measured imaged clearly, that is, the cross pattern can be seen clearly. In some examples, the working objective lens being in focus with the cross pattern may mean that the cross pattern is located in a focal plane of the working objective lens, and that the cross pattern is located within a field of view of the objective lens. In some examples, since the standard 2 is a flat plate with good flatness, the fact that any region to be measured of the standard 2 is located at the focal plane of the objective lens means that the cross pattern is located at the focal plane of the objective lens.

In some examples, the alignment of the working objective with the cross pattern may mean that the cross pattern is centered in the field of view of the working objective. In other words, the alignment of the working objective with the cross pattern may mean that the center of the field of view of the working objective (hereinafter simply referred to as the field center) coincides with the intersection of the cross pattern. In some examples, when the working objective is aligned with the cross pattern, the optical axis of the working objective may pass through the center of the cross pattern. In other words, the working objective lens may be aligned with the cross pattern when the optical axis of the working objective lens passes through the center of the cross pattern. Thereby, the cross pattern can be located in the center of the field of view of the working objective.

In some examples, the order of focusing and aligning to the cross pattern may be reversed.

Referring to fig. 4 (a), in some examples, after the working objective lens is focused and aligned to the cross pattern, the position of the first objective lens 21 in the first direction D1 may be taken as the first position P1. I.e. the position of the working objective lens in the Z-axis when the cross pattern is located in the focal plane of the working objective lens. In some examples, the first position P1 may be understood as the height of the work piece mirror relative to the load-bearing platform 10. In other examples, the first position P1 may be understood as the height of the work objective relative to the standard 2.

In some examples, the position of the carrying platform 10 in the predetermined plane may be taken as the second position P2 after the working objective lens is focused and aligned to the cross pattern. I.e. the position of the load-bearing platform 10 in the predetermined plane when the cross pattern is centered in the field of view of the working objective.

In some examples, when the working objective lens is focused and aligned to the cross pattern, that is, the center Q1 of the field of view of the first objective lens coincides with the cross pattern, the position of any point of the carrying platform 10 may be used as the second position P2. Since the surveying instrument 1 is measuring the standard 2, the load-bearing platform 10 and the standard 2 may be relatively stationary. Therefore, for the convenience of subsequent measurement, the position of any point on the standard 2 can be regarded as the position of the carrying platform 10, and preferably, the intersection point of the cross pattern can be regarded as the position of the carrying platform 10. That is, after the working objective lens is in focus and aligned with the cross pattern, the position of the intersection of the cross pattern at the preset plane may be taken as the second position P2 (see fig. 5).

In some examples, the measurement instrument 1 may further comprise a first measurement element. In some examples, a first measurement element may be used to obtain the first position P1. In some examples, the first measurement element may be a grating scale. In this case, since the grating scale has a characteristic of high detection accuracy, the position information of the first position P1 can be obtained more accurately to improve the measurement accuracy.

In some examples, the first measurement element may also be a PZT (piezoelectric ceramic) or like device.

Fig. 7 is a schematic view showing a rotary part 30 according to an example of the present disclosure.

As described above, in step S600, the third position P3 and the fourth position P4 may be obtained.

In some examples, the third position P3 and the fourth position P4 may be obtained after switching the work objective. In some examples, the second objective lens 22 of the plurality of objective lenses 20 may be made to be the working objective lens. In other words, the first objective lens 21 may be switched to the second objective lens 22 to obtain the third position P3 and the fourth position P4. In some examples, the second objective lens 22 may be any one of the plurality of objective lenses 20 different from the first objective lens 21, and may be, for example, an objective lens adjacent or not adjacent to the first objective lens 21.

In some examples, the measurement instrument 1 may further include a rotation part 30 for switching the plurality of objective lenses 20. The rotation part 30 may have a through hole 31 for disposing the plurality of objective lenses 20 (see fig. 7). In some examples, different objective lenses may be switched as the working objective lens by rotating the rotation part 30 in a preset order. This enables switching between different objective lenses as the working objective lens.

In some examples, the preset sequence may be a clockwise rotation or a counterclockwise rotation. In some examples, the rotating portion 30 may be referred to as a turret.

In some examples, the second objective lens 22 may be switched to perform the measurement on the standard 2 after being switched to be the working objective lens. In some examples, when the second objective lens 22 is switched as the working objective lens, the standard 2 may not be located at the focal plane of the second objective lens 22, for example, as shown in fig. 4 (b), the working objective lens is in an out-of-focus state. In some examples, the position of the second objective lens 22 may be adjusted to focus the second objective lens 22 in a cross pattern. In some examples, see (b) to (c) in fig. 4, the position of the second objective lens 22 is adjusted so that the cross pattern is located at the focal plane of the second objective lens 22. Thereby, a clear image of the cross pattern can be obtained.

In some examples, when the second objective lens 22 is switched to be the work objective lens, the intersection point of the center Q2 of the field of view of the second objective lens and the cross pattern may be deviated (see fig. 5), and at this time, the position of the carrying platform 10 may be adjusted to align the second objective lens 22 with the cross pattern, that is, the position of the carrying platform 10 may be adjusted to move the cross pattern to a position coinciding with the center Q2 of the field of view of the second objective lens. (see fig. 6). In some examples, the carrier platform 10 may have a higher precision of the transmission, thus enabling a faster and more accurate movement of the cross pattern to the second objective field center Q2.

In some examples, when the second objective lens 22 is in focus and aligned with the cross pattern, the position of the second objective lens 22 in the first direction D1 may be taken as a third position P3 (see (c) in fig. 4), and the position of the carrying platform 10 in the preset plane (i.e., the position of the center of the cross pattern in the preset plane) may be taken as a fourth position P4 (see fig. 6). Thus, the third position P3 and the fourth position P4 can be obtained by adjusting the position of the second objective lens 22 in the first direction D1 and adjusting the position of the carrying platform 10 on the preset plane.

In some examples, the first measurement element may be used to obtain the third position P3. In this case, since the grating scale has a feature of high detection accuracy, the position information of the third position P3 can be obtained more accurately to improve the measurement accuracy.

In some examples, the measuring instrument 1 further comprises a second measuring element for obtaining the second position P2 and the fourth position P4. In some examples, the second measurement element may be the same measurement device as the first measurement element. Thereby, the position information of the second position P2 and the fourth position P4 can be obtained more accurately.

In step S800, the working objective lens may be subjected to parfocal calibration based on the first position P1 and the third position P3.

In some examples, during the measurement, the working objective lens may be parfocal calibrated based on the first position P1 and the third position P3 as the working objective lens is switched between the first objective lens 21 and the second objective lens 22.

In some examples, the difference between the first position P1 and the third position P3 may be made a first error H1 (see fig. 4), and the working objective lens may be subjected to parfocal calibration based on the first error H1. In this case, the working objective lens can be subjected to parfocal calibration by obtaining the first position P1 and the third position P3 and based on the difference between the first position P1 and the third position P3, and the measurement accuracy of the measurement instrument 1 can be improved.

In an example, the first error H1 may be directly obtained based on the first measurement element.

In some examples, calibrating the working objective lens based on the first error H1 may refer to automatic compensation based on the first error H1 after the working objective lens is switched from the first objective lens 21 to the second objective lens 22 during measurement of the object. That is, after the working objective lens is switched from the first objective lens 21 to the second objective lens 22, the second objective lens 22 can be controlled to move to the third position P3 (i.e., when the object to be measured can be located at the position of the focal plane of the second objective lens 22) based on the first error H1. In this case, since the first error H1 has been obtained in advance, when the object to be measured is measured by switching the different objective lenses, the operating objective lens can automatically compensate to the third position P3 where the object to be measured can be located at the focal plane of the operating objective lens based on the first error H1, whereby the measurement efficiency of the measuring instrument 1 can be improved.

In step S1000, the working objective lens may be concentrically calibrated based on the second position P2 and the fourth position P4.

In some examples, the difference between the second position P2 and the fourth position P4 may be made a second error H2, and the working objective lens may be concentrically calibrated based on the second error H2. In this case, the concentric calibration of the working objective lens can be performed by obtaining the second position P2 and the fourth position P4 and based on the difference between the second position P2 and the fourth position, and the measurement accuracy of the measuring instrument 1 can be improved.

As described above, the loading platform 10 can move in a predetermined plane. In some examples, the load-bearing platform 10 may be configured to be movable along the second direction D2 and along a third direction D3 orthogonal to the second direction D2 within a preset plane. In this case, the movement of the platform 10 in the second direction D2 and the third direction D3 can move the standard 2 into the field of view of the working objective so that the working objective can be aligned with the cross pattern to obtain the fourth position P4, thereby facilitating subsequent calibration of the working objective based on the difference between the second position P2 and the fourth position P4. In some examples, the second direction D2 may be a direction parallel to the X-axis, and the third direction D3 may be a direction parallel to the Y-axis.

In some examples, the second error H2 may include a first sub-error H21 along the second direction D2 and a second sub-error H22 along the third direction D3, and the working objective lens may be concentrically calibrated based on the first sub-error H21 and the second sub-error H22. In some examples, the second error H2 may be decomposed into a first sub-error H21 along the second direction D2 and a second sub-error H22 along the third direction D3. In this case, when the object to be measured is measured, after different objective lenses are switched to be the working objective lens, the first sub-error H21 can be moved in the second direction D2 and the second sub-error H22 can be moved in the third direction D3 by the carrying platform 10 to move the object to be measured to the center of the field of view of the working objective lens, thereby performing concentric calibration on the working objective lens. In other words, the supporting platform 10 can move from the second position P2 to the fourth position P3 based on the second error H2 when the object is measured.

In some examples, the displacement of the carrying platform 10 from the second position P2 to the fourth position P4 may be obtained by a second measuring element to obtain the first sub-error H21 and the second sub-error H22. Thereby, the first sub-error H21 and the second sub-error H22 can be obtained for subsequent concentric calibration of the working objective lens.

In some examples, in steps S400 and S600, the center of field of view Q1 of the first objective lens may be taken as the second position P2 and the center of field of view Q2 of the second objective lens may be taken as the fourth position P4 without moving the carrying platform 10 (see fig. 5). The second error H2 is obtained by measuring the distance between the center of field Q1 of the first objective lens and the center of field Q2 of the second objective lens.

Fig. 8 is a flowchart illustrating a measurement method according to an example of the present disclosure.

In addition, referring to fig. 8, the present disclosure also provides a measuring method for measuring a parfocal error and a concentricity error of the plurality of objective lenses 20. The measurement method may include steps S200, S400, S600 included in the above calibration method, obtaining an parfocalization error based on the first position P1 and the third position P3 (step S820), and obtaining a concentricity error based on the second position P2 and the fourth position P4 (step S1200).

In an example, the parfocal error in step S820 may refer to a difference between the first position P1 and the third position P3. In an example, the concentricity error in step 1200 may refer to a difference between the second position P2 and the fourth position P4. For specific contents, reference may be made to steps S800 and S800, which are not described herein again.

Since the first objective lens 21 may be any one of the plurality of objective lenses 20, the second objective lens 22 may be any one of the plurality of objective lenses 20 different from the first objective lens 21. Therefore, a plurality of sets of first errors H1 and a plurality of sets of second errors H2 can be obtained based on the measurement method of the present disclosure. In other words, the first error H1 and the second error H2 between any two objective lenses can be obtained, for example, the first error H1 and the second error H2 between the objective lens a and the objective lens b, the first error H1 and the second error H2 between the objective lens a and the objective lens c, or the first error H1 and the second error H2 between the objective lens b and the objective lens c can be obtained. Therefore, the working objective lens can be automatically subjected to parfocal calibration and concentric calibration based on the multiple groups of first errors H1 and the multiple groups of second errors H2 during subsequent measurement of the object to be measured.

Fig. 9 is a block diagram showing a configuration of the calibration device 40 according to the example of the present disclosure.

In addition, the present disclosure also provides a calibration device 40 of the measuring instrument 1 (which may be simply referred to as the calibration device 40 hereinafter), and the calibration device 40 according to the present disclosure may also be referred to as a verification device, a calibration device, or the like, for example. It is to be understood that the names are for the purpose of illustrating the present disclosure and should not be taken as limiting. In some examples, the calibration device 40 may be used in the calibration method described above.

As described above, the surveying instrument 1 may include the carrying platform 10 movable in a preset plane and the plurality of objective lenses 20 movable in the first direction D1 perpendicular to the preset plane.

In some examples, the calibration device 40 may include a recording module 41, a processing module 42, a storage module 43, and a control module 44 (see fig. 9). The recording module 41 may be configured to record a first position P1 and a second position P2 when the first objective lens 21 measures the standard 2 having the cross pattern, where the first position P1 may be a position of the first objective lens 21 in the first direction D1 when the first objective lens 21 is focused on the cross pattern of the standard 2, and the second position P2 may be a position of the carrying platform 10 in the preset plane when the first objective lens 21 is aligned with the cross pattern. In some examples, the recording module 41 may be configured to record a third position P3 and a fourth position P4 when the second objective lens 22 measures the standard 2 with the cross pattern, where the third position P3 may be a position of the second objective lens 22 in the first direction D1 when the second objective lens 22 is focused on the cross pattern of the standard 2, and the fourth position P4 may be a position of the carrying platform 10 in a preset plane when the second objective lens 22 is aligned with the cross pattern (the related description may refer to steps S400 and S600, and will not be described herein again). In this case, the position of the objective lens when it is in focus on the cross pattern of the standard 2 is recorded to facilitate subsequent parfocal calibration of the working objective lens, and the position of the carrier platform 10 when it is in alignment with the cross pattern of the standard 2 is recorded to facilitate subsequent concentric calibration of the working objective lens.

In some examples, processing module 42 may be configured to obtain first error H1 based on first position P1 and third position P3, and obtain second error H2 based on second position P2 and fourth position P4. In some examples, the storage module 43 may be configured to store a plurality of sets of first errors H1 and a plurality of sets of second errors H2. Therefore, the working objective lens can be conveniently subjected to parfocal calibration and concentric calibration according to the multiple groups of first errors H1 and the multiple groups of second errors H2.

In some examples, the control module 44 may be configured to obtain the first error H1 and the second error H2 from the storage module 43 based on the switching condition of the working objective lens when the measuring instrument 1 switches the working objective lens, and control the working objective lens to move in the first direction D1 based on the first error H1 to parfocal the plurality of objective lenses 20, and control the carrying platform 10 to move in the preset plane to make the plurality of objective lenses 20 concentric based on the second error H2. In this case, when the measuring instrument 1 switches the working objective lens, the working objective lens can be automatically subjected to the parfocal calibration and the concentric calibration based on the first error H1 and the second error H2 obtained in advance, and then the object to be measured can still be located on the focal plane of the working objective lens and at the view center of the working objective lens after the switching of the working objective lens, so that the measuring instrument 1 can directly measure the object to be measured based on the switched working objective lens, and the measuring efficiency can be improved while the original measuring accuracy is maintained.

In some examples, a driving module 45 (see fig. 9) in signal connection with the control module 44 is further included, and the driving module 45 includes a first driving mechanism for driving the objective lens to move in the first direction D1 and a second driving mechanism for driving the carrying platform 10 to move in the plane corresponding to the preset plane. In this case, when the surveying instrument 1 switches the working objective lens, the first driving mechanism may drive the working objective lens to move from the first position P1 to the third position P3 based on the first error H1 obtained by the control module 44 to perform the parfocal calibration on the working objective lens, and the second driving mechanism may drive the carrying platform 10 to move from the second position P2 to the fourth position P4 based on the second error H2 obtained by the control module 44 to perform the concentric calibration on the working objective lens. That is, in the process of scanning the object to be measured, the first driving mechanism can drive the working objective lens to automatically perform parfocal compensation, and the second driving mechanism can drive the working objective lens to automatically perform concentric compensation.

According to the calibration method and the calibration device 40 provided by the present disclosure, a first error H1 for representing the degree of collimation of the working objective lens and a second error H2 for representing the degree of concentricity can be obtained in advance based on the standard 2 having the cross pattern, when the object to be measured is measured, after different objective lenses are switched as the working objective lenses, the measurement instrument 1 can control the movement of the working objective lenses in the first direction D1 based on a plurality of groups of first errors H1 obtained in advance to perform the alignment calibration on the working objective lenses, and control the movement of the carrying platform 10 in the second direction D2 based on a plurality of groups of second errors H2 and a plurality of groups of second errors H2 obtained in advance to perform the concentric calibration on the working objective lenses, thereby reducing the occurrence of the phenomenon of the working objective lenses of being out-of-focus and/or out-of-center as much as possible, and further improving the measurement efficiency and the measurement accuracy in the process of measuring the object to be measured.

While the present disclosure has been described in detail in connection with the drawings and examples, it should be understood that the above description is not intended to limit the disclosure in any way. Those skilled in the art can make modifications and variations to the present disclosure as needed without departing from the true spirit and scope of the disclosure, which fall within the scope of the disclosure.

Claims (10)

1. A calibration method for a surveying instrument including a carrying platform movable in a predetermined plane and a plurality of objective lenses movable in a first direction perpendicular to the predetermined plane, the calibration method for calibrating a working objective lens when switching the objective lenses, comprising: placing a standard part with a cross pattern on the bearing platform; enabling a first objective lens in the objective lenses to be used as a working objective lens, enabling the working objective lens to be focused and aligned to the cross pattern, enabling the position of the first objective lens in the first direction to be used as a first position, and enabling the position of the bearing platform on the preset plane to be used as a second position; a second objective lens in the objective lenses is used as a working objective lens, the working objective lens is used for measuring the standard piece, the position of the second objective lens is adjusted so that the second objective lens is focused on the cross pattern, the position of the bearing platform is adjusted so that the second objective lens is aligned to the cross pattern, the position of the second objective lens in the first direction is used as a third position, and the position of the bearing platform on the preset plane is used as a fourth position; in the measuring process, when the working objective lens is switched between the first objective lens and the second objective lens, performing parfocal calibration on the working objective lens based on the first position and the third position; and concentrically calibrating the working objective lens based on the second position and the fourth position.

2. The calibration method of claim 1, wherein:

the surveying instrument further includes a rotation section for switching the plurality of objective lenses, and different objective lenses are switched as working objective lenses by rotating the rotation section in a preset order.

3. The calibration method according to claim 1, wherein:

and taking the difference value between the first position and the third position as a first error, and carrying out parfocal calibration on the working objective lens based on the first error.

4. The calibration method of claim 1, wherein:

the measuring instrument further comprises a first measuring element for obtaining the first position and the third position, wherein the first measuring element is a grating ruler.

5. The calibration method according to claim 1, wherein:

and taking the difference value between the second position and the fourth position as a second error, and performing concentric calibration on the working objective lens based on the second error.

6. The calibration method of claim 5, wherein:

the carrying platform is configured to be movable in a second direction within the preset plane and in a third direction orthogonal to the second direction, the second error comprises a first sub-error in the second direction and a second sub-error in the third direction, and the concentric calibration of the working objective lens is performed based on the first sub-error and the second sub-error.

7. The calibration method of claim 6, wherein:

the measuring instrument further comprises a second measuring element for obtaining the second position and the fourth position, and the displacement of the carrying platform from the second position to the fourth position is obtained through the second measuring element to obtain the first sub-error and the second sub-error.

8. The calibration method of claim 1, wherein:

when the working objective lens focuses the cross pattern, the cross pattern is located on the focal plane of the working objective lens, and when the working objective lens is aligned with the cross pattern, the optical axis of the working objective lens passes through the center of the cross pattern.

9. A calibration device for a surveying instrument comprising a carrier platform movable in a predetermined plane and a plurality of objective lenses movable in a first direction perpendicular to the predetermined plane, characterized by: the calibration device comprises a recording module, a processing module, a storage module and a control module, wherein the recording module is used for recording a first position and a second position when a first objective lens measures a standard part with a cross pattern, and recording a third position and a fourth position when a second objective lens measures the standard part with the cross pattern, the first position is the position of the first objective lens in the first direction when the first objective lens is focused on the cross pattern of the standard part, the second position is the position of the bearing platform in the preset plane when the first objective lens is aligned with the cross pattern, the third position is the position of the second objective lens in the first direction when the second objective lens is focused on the cross pattern of the standard part, and the fourth position is the position of the bearing platform in the preset plane when the second objective lens is aligned with the cross pattern; the processing module is configured to obtain a first error based on the first location and the third location and a second error based on the second location and the fourth location; the storage module is configured to store a plurality of sets of the first errors and a plurality of sets of the second errors, and the control module is configured to obtain the first errors and the second errors from the storage module based on the switching condition of the working objective when the measuring instrument switches the working objective, control the working objective to move in the first direction based on the first errors so as to make the plurality of objective lenses in parfocal state, and control the carrying platform to move in the preset plane based on the second errors so as to make the plurality of objective lenses concentric.

10. The calibration device of claim 9, wherein:

the driving module comprises a first driving mechanism used for driving the working objective lens to move in the first direction and a second driving mechanism used for driving the bearing platform to move in the preset plane.

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