CN114706182A - Method for assembling circular grating for optical device - Google Patents
Method for assembling circular grating for optical device Download PDFInfo
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- CN114706182A CN114706182A CN202210270640.9A CN202210270640A CN114706182A CN 114706182 A CN114706182 A CN 114706182A CN 202210270640 A CN202210270640 A CN 202210270640A CN 114706182 A CN114706182 A CN 114706182A
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Abstract
The invention provides an assembling method of a circular grating for an optical device, which comprises the following steps: arranging the circular grating on the grating rotating shaft so that the circular grating can rotate relative to the base by taking the shaft center of the grating rotating shaft as a rotating center; capturing and presenting a grating line image with a grating line in the rotation process of the circular grating, and adjusting the relative position of the circular grating and a grating rotation shaft to enable the edge of one side of the grating line image to move between a first edge position and a second edge position; capturing grating line images of the circular grating at least two positions, converting the grating line images into a first electric signal and a second electric signal, obtaining an eccentricity error of the circular grating based on the first electric signal and the second electric signal, and determining whether the eccentricity error is smaller than a preset threshold value; and a mounting step, namely fixing the relative position of the circular grating and the grating rotating shaft if the eccentricity error is smaller than a preset threshold value. In this case, the relative position of the circular grating and the grating rotation axis can be adjusted based on the difference between the center of the circle of the circular grating and the axis of the grating rotation axis.
Description
The application is a divisional application of a patent application with an application date of 30/07/2021, an application number of 2021108683463, entitled assembling method of circular grating.
Technical Field
The present invention relates generally to laser measuring instruments, and more particularly to methods of assembling circular gratings for optical devices.
Background
The angular position of the coordinates can be accurately determined by an encoder made of a circular grating, and thus, a circular grating is often used for a laser tracker. Among various error sources affecting the accuracy of the encoder, the degree of influence of the eccentricity difference on the accuracy of the encoder is large, and the degree of influence of the eccentricity difference on the accuracy of the encoder can be reduced by an appropriate assembling method of the circular grating.
In the prior art, the installation error of the circular grating is shot by using the surface scribed line of the circular grating, and the eccentricity of the grating disc is obtained based on the surface scribed line of the circular grating. For example, CN201910278871.2 discloses an error source analysis-based method for correcting angle measurement errors of a circular grating sensor, which uses a CCD camera and a microscope of an eccentricity detection device to take an image of the surface lines of a grating disk of the circular grating sensor, and performs an image processing method on the coordinates of the right end points of the lines of each image, respectively, to calculate the eccentricity of the mounted grating disk and the mounting eccentricity angle.
However, this method is limited to the accuracy of the image photograph of the reticle on the surface of the grating disk of the circular grating sensor, and it is difficult to meet the accuracy requirements of the laser tracker.
Disclosure of Invention
The present invention has been made in view of the above-described conventional state of the art, and an object thereof is to reduce an eccentricity error when a circular grating is attached.
To achieve the above object, the present invention provides a method of mounting a circular grating on a grating rotating shaft provided on a base, the grating rotating shaft being arranged to be rotatable with respect to the base around an axis of the grating rotating shaft as a rotation center, the method comprising: a preparation step of arranging the circular grating on the grating rotation shaft so that the circular grating can rotate relative to the base around an axis of the grating rotation shaft as a rotation center; an adjusting step of capturing a grating line image of the circular grating in the process of rotating the circular grating, and adjusting the relative position of the circular grating and the grating rotating shaft so that the edge of one side of the grating line image moves to be within the dynamic range of the side edge; a detection step of rotating the circular grating, capturing grating line images of the circular grating at least two positions on the circular grating, converting the grating line images into a first electric signal and a second electric signal, obtaining an eccentricity error of the circular grating based on the first electric signal and the second electric signal, and determining whether the eccentricity error is smaller than a preset threshold value; and an installation step, if the eccentricity error is smaller than the preset threshold, fixing the relative position of the circular grating and the grating rotating shaft.
In this case, the difference between the center of the circle of the circular grating and the axis of the grating rotation shaft can be obtained, and the relative position between the circular grating and the grating rotation shaft can be adjusted based on the difference between the center of the circle of the circular grating and the axis of the grating rotation shaft.
In the assembling method according to the present invention, optionally, in the adjusting step, an edge on one side of the raster image is reciprocally moved between a first edge position and a second edge position during rotation of the circular raster. In this case, the first moving distance of the edge of the grating line can be marked, and the eccentricity error of the circular grating can be calculated by the first moving distance of the edge of the grating line.
In the assembling method according to the present invention, alternatively, in the adjusting step, when the one edge of the raster image is close to the first edge position or the second edge position, the rotation of the circular raster may be stopped, and the one edge of the raster image may be moved to a midpoint between the first edge position and the second edge position by adjusting a relative position between the circular raster and the raster rotation axis. In this case, since the first moving distance of the edge of the grating line is twice as large as the eccentricity error of the circular grating, the eccentricity error can be reduced.
In the assembling method according to the present invention, it is preferable that the adjusting step adjusts the relative positions of the circular grating and the grating rotation shaft so that the center of the circular grating and the axis of the grating rotation shaft are close to each other. In this case, the eccentricity error of the circular grating can be reduced.
In addition, in the assembling method according to the present invention, optionally, if the eccentricity error is not smaller than the preset threshold, the adjusting step and the detecting step are repeated to make the eccentricity error smaller than the preset threshold, where the preset threshold is 1 to 10 micrometers. In this case, the eccentricity error can be adjusted by the first detecting step position and the adjusting step a plurality of times, and whether the eccentricity error meets the requirement or not can be judged by the second detecting step a plurality of times, and the eccentricity error can be adjusted to 1 to 10 micrometers by the adjusting step, so that the assembling accuracy of the circular grating can be ensured.
In the assembling method according to the present invention, the detecting step may be performed simultaneously with the adjusting step. In this case, the raster image of the circular raster, the first electric signal, and the second electric signal can be obtained at the same time, and the eccentricity error of the circular raster can be adjusted.
In the assembling method according to the present invention, it is preferable that the detecting step includes presenting a waveform of the first electric signal and a waveform of the second electric signal so as to fix the waveform of the first electric signal, and calculating the eccentricity error based on a dynamic range of a phase of the second electric signal. In this case, the eccentricity error of the circular grating can be calculated using the dynamic range of the phase between the first electric signal and the second electric signal (that is, the second moving distance of the waveform of the second electric signal in the oscilloscope with the first electric signal as a reference).
In addition, in the assembling method according to the present invention, optionally, the grid image is presented by a display module, and an edge of one side of the grid image is located within a display frame of the display module. In this case, the raster image can be intuitively displayed by the display module, and the relative position of the circular raster and the raster rotation axis can be adjusted based on the raster image.
Further, in the assembling method according to the present invention, optionally, in the preparing step, the circular grating is disposed on the grating rotation shaft using a fastener and a hub, and a relative position between the circular grating and the grating rotation shaft is made adjustable. In this case, the relative position between the circular grating and the hub can be fixed through the fastener and the hub, so that the circular grating can be kept stable when rotating relative to the base, and meanwhile, the relative position between the circular grating and the hub (namely the relative position between the circular grating and the grating rotating shaft) can be adjusted under the action of the knocking mechanism or the ejector pin.
In the assembling method according to the present invention, optionally, in the mounting step, the circular grating is fixed to the hub by a fixing agent to fix a relative position of the circular grating and the grating rotation axis. In this case, since the hub and the grating rotation shaft have high processing accuracy, it is considered that the hub and the grating rotation shaft are overlapped in axial center, and thus the relative position of the circular grating and the grating rotation shaft can be determined by fixing the relative position of the circular grating to the hub.
Thus, the present invention can provide an assembling method for reducing an eccentricity error when assembling a circular grating.
Drawings
Embodiments of the invention will now be explained in further detail by way of example only with reference to the accompanying drawings.
Fig. 1 is a schematic flow chart showing a method of assembling a circular grating according to an embodiment of the present invention.
Fig. 2 is a schematic sectional view showing a circular grating according to the embodiment of the present invention attached to a grating rotary shaft and passing through an axis of the grating rotary shaft.
Fig. 3 is an exploded view showing that a circular grating according to the embodiment of the present invention is attached to a grating rotation shaft.
Fig. 4 is a flowchart illustrating the adjustment steps of the method for assembling a circular grating according to the embodiment of the present invention.
Fig. 5 is a schematic view showing a scene where a grid line is obtained in the adjustment step of the method for assembling a circular grating according to the embodiment of the present invention.
Fig. 6 is a schematic diagram showing a change in the edge of the gate line image at the adjustment step according to the embodiment of the present invention.
Fig. 7 is a schematic view showing a scene in which the first electric signal and the second electric signal are obtained in the adjustment step of the method for assembling a circular grating according to the embodiment of the present invention.
Fig. 8 is a schematic diagram of the first electric signal and the second electric signal in an oscilloscope showing the second adjustment step of the method for assembling a circular grating according to the embodiment of the present invention.
Detailed Description
All references cited herein are incorporated by reference in their entirety as if fully set forth. Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. General guidance for many of the terms used in this application is provided to those skilled in the art. One skilled in the art will recognize many methods and materials similar or equivalent to those described herein that can be used in the practice of the present invention. Indeed, the invention is in no way limited to the methods and materials described.
The assembling method of the circular grating for reducing the eccentricity error according to the present invention will be described below with reference to the accompanying drawings.
The invention relates to an assembly method of a circular grating for reducing eccentricity errors, in particular to an assembly method of a circular grating for a precise optical device. In some examples, the assembling method of the circular grating for reducing the eccentricity error according to the present invention may be simply referred to as an assembling method. In some examples, the assembling method of the circular grating for reducing the eccentricity error according to the present invention may be used to detect the eccentricity error. In some examples, the assembling method of the circular grating for reducing the eccentricity error according to the present invention can be used for reducing the eccentricity error. In some examples, the eccentricity error may be a radial difference between a center of a circle of the circular grating and an axis of a grating rotation axis.
The assembling method of the circular grating for reducing the eccentric error can measure the radial difference between the center of the circular grating and the axis of the grating rotating shaft by using the first detection step and the detection step respectively, and after the first detection step is finished, the relative position of the circular grating and the grating rotating shaft is adjusted according to the position of the edge of the grating line image of the circular grating, so that the eccentric error can be reduced. The assembling method of the circular grating for reducing the eccentric error utilizes the detection step to measure the eccentric error again, and the measurement precision of the detection step is higher than that of the first detection step, so that whether the eccentric error meets the requirement or not can be judged under a higher measurement standard. Meanwhile, the assembling method of the circular grating for reducing the eccentric error repeatedly executes the adjusting step, so that the influence of misoperation or system error on the eccentric error of the circular grating can be reduced.
In some examples, the assembling method of the circular grating can be used for mounting the circular grating on a grating rotating shaft. In some examples, the circular grating and the grating rotation axis according to the present invention can be applied to a precision optical instrument. In some examples, the precision optical instrument may include a laser tracker, a laser interferometer, an electro-optic theodolite, a radar, or an antiaircraft director.
In some examples, the circular grating and the grating rotation axis to which the present invention relates may be used as an encoder. In this case, the position angle of the auxiliary measuring device can be accurately determined using the circular grating.
Fig. 1 is a schematic flow chart showing a method of assembling the circular grating 13 according to the embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing the circular grating 13 according to the embodiment of the present invention attached to the grating rotary shaft 12, passing through the axis of the grating rotary shaft. Fig. 3 is an exploded view showing that the circular grating 13 according to the embodiment of the present invention is attached to the grating rotation shaft 12.
In some examples, as shown in fig. 1, in some examples, the circular grating 13 assembly method may include: a preparation step (step S100), an adjustment step (step S200), a detection step (step S300), and an installation step (step S400).
In step S100, the preparing step may include: the circular grating 13 is disposed on the grating rotary shaft 12 by a fastener 15 so that the circular grating 13 is disposed to be rotatable with respect to the base 11 about the axis of the grating rotary shaft 12 as a rotation center by the grating rotary shaft 12, and the base 11 has a driving device for driving the grating rotary shaft 12 to rotate. In some examples, as shown in fig. 2 and 3, the composite mechanism 1 may be formed by a combination of a base 11, a grating rotational axis 12, a hub 14, a circular grating 13, and fasteners 15. In some examples, the circular grating 13 may be mounted to the grating rotation shaft 12.
In some examples, the circular grating 13 may be mounted to the grating rotation axis 12 via a hub 14, and a geometric center (e.g., a center) of the hub 14 may be mounted on the grating rotation axis 12 via the hub 14 and coincide with an axial center of the grating rotation axis 12.
In some examples, the circular grating 13 may have a first through hole, the hub 14 may have a second through hole, the first through hole may be larger than the second through hole, and the second through hole may be sized to match the grating rotation axis 12. In some examples, the grating rotational axis 12 may have an upper end and a lower end, wherein the hub 14 may be mounted at the upper end, and the radius of the upper end may be smaller than the radius of the lower end.
In some examples, the size of the second through hole may match the grating rotation axis 12 may mean that the radius of the through hole is the same as the radius of the upper end of the grating rotation axis 12. In some examples, the size of the second through hole may match the grating rotation axis 12 may mean that the radius of the upper end of the second through hole is slightly smaller than the radius of the upper end of the grating rotation axis 12. In this case, the hub 14 can be attached to the grating rotary shaft 12, and the hub 14 can be supported by the lower end portion of the grating rotary shaft 12 to rotate the hub 14 around the axial center of the grating rotary shaft 12.
In some examples, the grating rotation shaft 12 may be disposed on the base 11, and the grating rotation shaft 12 may rotate with respect to the base 11 with a shaft center of the grating rotation shaft 12 as a rotation center. In some examples, the circular grating 13 may be configured to rotate relative to the base 11 with the axis of the grating rotation shaft 12 as a rotation center by the grating rotation shaft 12.
In some examples, the circular grating 13 may be placed on the upper surface of the hub 14. In some examples, as described above, the circular grating 13 may be disposed on the hub 14 using the fasteners 15.
In some examples, the fastener 15 may have a variety of fastening means. For example, the fastener 15 may be provided with at least one set screw 151. In this case, it is possible to place the circular grating 13 between the fastener 15 and the hub 14, and mount the fastener 15 to the hub 14 with the fixing screw 151 so that the circular grating 13 is fixed between the fastener 15 and the hub 14.
In some examples, the fastener 15 may have 1, 2, 3, 4, or 5 set screws 151, and preferably, the fastener 15 may be provided with 3 set screws 151.
In some examples, the radius of the first through hole of the circular grating 13 may be larger than the radius of the second through hole of the hub 14. In this case, the fixing screw 151 of the fastener 15 may pass through the first through hole of the circular grating 13 and be coupled with the hub 14.
In some examples, the fastener 15 may have a clamping structure, for example, the fastener 15 may have a first clamping arm and a second clamping arm. In this case, the circular grating 13 and the hub 14 can be clamped and fixed together by the first clamp arm and the second clamp arm.
In some examples, in step S100, the circular grating 13 may be arranged on the grating rotation shaft 12 using the fastener 15 and the hub 14, and the relative position between the circular grating 13 and the grating rotation shaft 12 may be adjusted. In this case, the relative positions of the circular grating 13 and the hub 14 can be fixed by the fastener 15 and the hub 14, so that the circular grating 13 is stable when rotating relative to the base 11, and the relative position between the circular grating 13 and the hub 14 (i.e., the relative position between the circular grating 13 and the grating rotation shaft 12) can be adjusted by a tapping mechanism (described later) or an ejector pin.
In some examples, the base 11 may have an illumination device (not shown) capable of illuminating, and a driving device (not shown) that drives the grating rotation shaft 12 to rotate.
In some examples, the lighting device and the driving device may also be provided to the carrier device 2.
In some examples, the base 11 may further have an adjusting screw (not shown) that adjusts the levelness of the base 11. In some examples, the base 11 may have 1, 2, 3, 4, or 5 adjustment screws, and preferably, the base 11 may have 3 adjustment screws. In this case, the susceptor 11 and, hence, the circular grating 13 can be kept horizontal, so that the accuracy of testing the eccentricity error can be improved.
Fig. 4 is a flowchart illustrating the adjustment steps of the method for assembling the circular grating 13 according to the embodiment of the present invention. Fig. 5 is a schematic view showing a scene in which a grating line is obtained in the adjustment step of the method for assembling the circular grating 13 according to the embodiment of the present invention.
In step S200, as shown in fig. 4, the adjusting step may include: a gate line image is obtained (step S210), a dynamic range of an edge of the gate line image is determined (step S220), and position adjustment is performed (step S230).
In some examples, in step S200, may include obtaining a grid image. In some examples, obtaining the grating line image may be used to preliminarily detect a radial difference between the center of the circular grating 13 and the axis of the grating rotation shaft 12.
In some examples, the grating line image of the circular grating 13 may be captured during rotation of the circular grating 13, and the relative position of the circular grating 13 and the grating rotation axis 12 is adjusted to move the edge of one side of the grating line image into the dynamic range of the side edge.
In some examples, as shown in fig. 5, the composite structure 1 may be placed in a carrier 2. In some examples, the carrier 2 may include a carrier platform 21, a support 22, and a first sensing module 23.
In some examples, the first sensing module 23 may be used to receive a gate line image of the circular grating 13 and display the gate line image having the gate lines using the first display module 3. In other words, the grid line image may be presented through the display module 3, and an edge of one side of the grid line image is located within the display frame of the display module 3. In this case, the raster image can be intuitively displayed by the display module 3, and the relative position of the circular raster 13 and the raster rotation axis 12 can be adjusted based on the raster image.
In some examples, the first sensing module 23 may be a Charge Coupled Device (CCD) camera. In this case, since the CCD camera is small in size, light in weight, free from the influence of a magnetic field, and good in vibration resistance, the stability in measuring a grid line image can be improved.
In some examples, the first sensing module 23 may be disposed on the support 22. In some examples, the position of the first sensing module 23 may be adjusted by the bracket 22. In this case, the first sensing module 23 can be moved such that the first sensing module 23 is aligned with an edge of one side of the gate line image.
In some examples, the position of the base 11 may be moved to change the relative position of the first sensing module 23 and the circular grating 13. In this case, the base 11 can be moved to align the first sensing module 23 with the edge of one side of the gate line image.
In some examples, the first display module 3 may have a display screen. In some examples, the first display module 3 may display the image received by the first sensing module 23. In some examples, the first display module 3 may display a gate line image having gate lines received by the first sensing module 23.
Fig. 6 is a schematic diagram showing a change in the edge of the gate line image at the adjustment step according to the embodiment of the present invention.
In some examples, the edge of the gate line image may be understood in a manner that a direction of each of the stripes of the gate lines may be the same as a direction of the gate lines of the circular grating 13, the direction of the gate lines of the circular grating 13 may be the same as a radial direction, each of the stripes of the gate lines may have an end portion, and connecting the end portions of the same end of each of the stripes may obtain an edge perpendicular to the direction of the gate lines.
In some examples, the edge of the gate line image may be substantially the same as the shape of the circular grating 13, and the edge of one side of the gate line image may refer to at least a part of the edge of the gate line image.
In some examples, the first sensing module 23 may be moved to cause the first display module 3 to display the edge of the gate line image. In some examples, the base 11 may be moved to cause the first display module 3 to display the edge of the grid line image.
In some examples, the driving device may be activated to rotate the circular grating 13 relative to the base 11 with the axis of the grating rotation shaft 12 as a rotation center by the grating rotation shaft 12. In this case, if the center of the circular grating 13 does not coincide with the rotation center of the circular grating 13, the grating line image changes periodically. In this case, whether the center of the circular grating 13 coincides with the rotation center of the circular grating 13 can be determined based on whether or not the grating line image has a periodic change.
In some examples, after step S210, the dynamic range of the edge of the raster image may be determined (i.e., step S220).
In some examples, as shown in fig. 6, if the center of the circular grating 13 does not coincide with the rotation center of the circular grating 13, the edge of the grating line image may periodically move within a certain range during the rotation of the circular grating 13. Specifically, the edge of the grating line image may reciprocate within a certain range during the rotation of the circular grating 13.
In some examples, the moving direction of the edge of the gate line may be changed by rotating the first sensing module 23.
In some examples, the edges of the gate lines may be recorded at the first edge position a1 and the second edge position a2 in the first display module 3.
In some examples, the first edge position a1 may be any position of the edge of the grid line during the reciprocating movement. In some examples, the second edge position a2 may be any one of the positions of the edge of the gate line during the reciprocating movement different from the first edge position a 1. In this case, the magnitude of the eccentricity error can be roughly estimated from the distance between the first edge position a1 and the second edge position a 2. Preferably, as shown in fig. 6, the first edge position a1 and the second edge position a2 may be two ends of the reciprocating range of the edge of the gate line, that is, the edge of the gate line may reciprocate between the first edge position a1 and the second edge position a2 during the movement. In other words, the circular grating 13 can be rotated with respect to the base 11 by the grating rotation shaft 12 with the shaft center of the grating rotation shaft 12 as a rotation center, and the edge of the grating line can be moved back and forth between the first edge position a1 and the second edge position a 2. In this case, the first moving distance L1 of the edge of the grating line can be marked, and the eccentricity error of the circular grating 13 can be calculated by the first moving distance L1 of the edge of the grating line. In some examples, the dynamic range may be the region between the first edge position a1 and the second edge position a 2.
In some examples, the first moving distance L1 of the edge of the grating line may be twice the eccentricity error of the circular grating 13. In other words, if the center of the circular grating 13 coincides with the rotation center, the edge of the grating line should be in a stationary state when the circular grating 13 rotates relative to the base 11, so that the eccentricity error of the circular grating 13 can be calculated, and whether the center of the circular grating 13 coincides with the rotation center can be determined.
In some examples, after step S220, a position adjustment may be performed (i.e., step S230). In some examples, step S230 may be used to adjust a radial difference (i.e., an eccentricity error) between the center of the circular grating 13 and the axis of the grating rotation shaft 12 (the rotation center of the circular grating 13).
In some examples, when the edge of the grid line is at the first edge position a1 or the second edge position a2, the rotation of the circular grating 13 may be stopped, and the relative position of the circular grating 13 to the grating rotation axis 12 is changed to move the edge of the grid line between the first edge position a1 and the second edge position a2 (i.e., within the dynamic range).
In some examples, a tapping mechanism (not shown) may be used to change the relative positions of the circular grating 13 and the boss 14, so that the position of the edge of the grating on the display device may be changed. In this case, the relative position of the center of the circular grating 13 and the rotation center can be adjusted by changing the relative position of the circular grating 13 and the hub 14, so that the eccentricity error can be adjusted, and the change of the eccentricity error in the process of moving the circular grating 13 can be judged by the edge of the grating line.
In some examples, the relative position of the circular grating 13 and the hub 14 may be changed using a fine translation mechanism (not shown). Specifically, the fine tuning translation mechanism may be installed on any side of the base 11 through the bracket 22, and the fine tuning translation mechanism may include a push rod and a knob for controlling the push rod to move, and the push rod may point to the center of the circle of the circular grating 13. In this case, the knob control push rod can be used to push the circular grating 13 to change the relative position of the circular grating 13 and the hub 14.
In some examples, the fine translation mechanism may be a micro-drum. In some examples, the push rod of the fine tuning translation mechanism may be on a line connecting the center of the circular grating 13 and the first sensing module 23.
In some examples, in step S200, the relative positions of the circular grating 13 and the grating rotation shaft 12 may be adjusted in such a manner that the center of the circular grating 13 and the axis of the grating rotation shaft 12 are close to each other. In this case, the eccentricity error of the circular grating 13 can be reduced.
In some examples, when the edge moves to the first edge position a1 or the second edge position a2, the rotation may be stopped and the relative position of the circular grating 13 and the hub 14 may be changed using a tapping mechanism or a fine translation mechanism. The direction in which the knocking mechanism knocks the circular grating 13 or the direction in which the fine tuning translation mechanism pushes the circular grating 13 may be a direction pointing from the first sensing module 23 to the center of the circular grating 13. In this case, since the center of the circular grating 13, the rotation center of the circular grating 13, and the first sensing module 23 are collinear when the edge is moved to the first edge position a1 or the second edge position a2, the fine tuning translation mechanism can push the circular grating 13 in an appropriate direction to reduce the eccentricity error.
In some examples, before changing the relative position of the circular grating 13 and the hub 14, a portion of the set screw 151 may be adjusted to reduce the pressure of the press block and the hub 14 on the circular grating 13, and the set screw 151 may be tightened after striking the circular grating 13. In this case, it is possible to facilitate adjustment of the relative position of the circular grating 13 and the hub 14.
In some examples, the set screw 151 may not be adjusted when changing the relative position of the circular grating 13 and the hub 14. In this case, the influence on the relative position of the circular grating 13 and the boss 14 when the fixing screw 151 is tightened can be reduced.
In some examples, after the first edge position a1 and the second edge position a2 are obtained, the relative position of the circular grating 13 to the grating rotation axis 12 may be changed to move the edge of the grating line to the midpoint of the first edge position a1 and the second edge position a 2. Specifically, in step S200, when the side of the raster image is close to the first edge position a1 or the second edge position a2, the rotation of the circular raster 13 may be stopped, and the edge on the raster image side may be moved to the midpoint between the first edge position a1 and the second edge position a2 by adjusting the relative positions of the circular raster 13 and the raster rotation shaft 12. In this case, since the first moving distance L1 of the edge of the grating line is twice the eccentricity error of the circular grating 13, the eccentricity error can be reduced.
Fig. 7 is a schematic view showing a scene in which the first electrical signal CH1 and the second electrical signal CH2 are obtained in the adjustment step of the method for assembling the circular grating 13 according to the embodiment of the present invention. Fig. 8 is a schematic diagram showing the first electrical signal CH1 and the second electrical signal CH2 according to the embodiment of the present invention in the oscilloscope 5.
In some examples, a detection step may be included in the assembly method.
In step S300, the circular grating 13 may be rotated, and a grating line image of the circular grating 13 is captured and converted into the first electrical signal CH1 and the second electrical signal CH2 at least two positions on the circular grating 13 passing through the diameter of the circular grating 13, an eccentricity error of the circular grating 13 is obtained based on the first electrical signal CH1 and the second electrical signal CH2, and it is determined whether the eccentricity error is less than a preset threshold.
In some examples, the eccentricity error of the circular grating 13 may be obtained based on the phase difference of the first and second electric signals CH1 and CH2, and it may be determined whether the eccentricity error is less than a preset threshold.
In step S300, as shown in fig. 7, the second sensing block 4a and the third sensing block 4b disposed at opposite sides of the circular grating 13 may be used to receive the grating image and obtain the first electrical signal CH1 and the second electrical signal CH2, respectively, and the eccentricity error may be calculated based on the first electrical signal CH1 and the second electrical signal CH2 in the detecting step. In this case, the eccentricity error can be obtained in a more accurate manner, and it can be determined whether the eccentricity error of the circular grating 13 is reduced in step S200, and whether the eccentricity error of the circular grating 13 satisfies the requirement.
In some examples, the second and third sensing modules 4a and 4b may be disposed above the circular grating 13 and receive a grating line image. In some examples, the centers of the second sensing module 4a, the third sensing module 4b and the circular grating 13 may be on the same straight line. In other words, the second sensing module 4a and the third sensing module 4b may be disposed on opposite sides of the circular grating 13, respectively. In this case, two sets of electrical signals matching the opposite sides of the circular grating 13 can be obtained, and the eccentricity error of the circular grating 13 can be measured because the phase difference of the two sets of electrical signals changes periodically when the eccentricity error exists.
In some examples, the second and third sensing modules 4a and 4b may be the same distance from the center of the circular grating 13. In some examples, the second sensing module 4a and the third sensing module 4b may be disposed at both ends of a diameter of the circular grating 13. In some examples, the second sensing module 4a and the third sensing module 4b may be disposed on the circumference of the circular grating 13.
In some examples, the second and third sensing modules 4a and 4b may receive phase grid images and obtain the first and second electrical signals CH1 and CH2, respectively. In this case, the first electrical signal CH1 and the second electrical signal CH2 can be obtained, and further the eccentricity error can be obtained by using the first electrical signal CH1 and the second electrical signal CH 2.
In some examples, the second and third sensing modules 4a and 4b may be photosensors.
In some examples, the second sensing module 4a and the third sensing module 4b may be connected to an oscilloscope 5. In some examples, the second sensing module 4a may be connected to a first channel of an oscilloscope 5, and the third sensing module 4b may be connected to a second channel of the oscilloscope 5. In this case, the waveforms of the first electrical signal CH1 and the second electrical signal CH2 can be displayed using two channels of the oscilloscope 5.
In some examples, the oscilloscope 5 may be adjusted such that the oscilloscope 5 displays the stationary first electrical signal CH 1. In this case, since the center of the circular grating 13 does not coincide with the rotation center of the circular grating 13, the phase difference between the first electrical signal CH1 and the second electrical signal CH2 can be periodically changed, and it can be determined whether or not the center of the circular grating 13 coincides with the rotation center of the circular grating 13 in the case of the oscilloscope 5 by the second electrical signal CH 2. Specifically, when the second electrical signal CH2 and the first electrical signal CH1 are stationary relative to each other, it can be considered that the center of the circular grating 13 coincides with the rotation center of the circular grating 13. When the second electrical signal CH2 and the first electrical signal CH1 move relative to each other, it can be considered that the center of the circular grating 13 and the rotation center of the circular grating 13 do not coincide with each other.
In some examples, as shown in fig. 8, if the center of the circle of the circular grating 13 and the center of rotation of the circular grating 13 do not coincide, the phase difference between the first electrical signal CH1 and the second electrical signal CH2 may periodically change. In some examples, in step S300, the eccentricity error is calculated based on the dynamic range of the phase of the second electrical signal CH2 by presenting the waveform of the first electrical signal CH1 and the waveform of the second electrical signal CH2 in a manner that fixes the waveform of the first electrical signal CH1 (i.e., the first point signal CH1 is relatively stationary in the oscilloscope 3). In this case, the eccentricity error of the circular grating 13 can be calculated by using the dynamic range of the phase between the first electrical signal CH1 and the second electrical signal CH2 (that is, the second movement distance L2 of the waveform of the second electrical signal CH2 in the oscilloscope 5 with the first electrical signal CH1 as a reference).
In some examples, the eccentricity error may be calculated based on the second electrical signal CH2 at the second movement distance L2 of the oscilloscope 5. For example, the larger the eccentricity error of the circular grating 13, the larger the second moving distance L2 of the oscilloscope 5 of the second electrical signal CH 2. In some examples, the second moving distance L2 of the second electrical signal CH2 on the oscilloscope 5 may be represented by a phase, for example, the second moving distance L2 of the second electrical signal CH2 on the oscilloscope 5 may be 180 °, that is, the phase difference between the first electrical signal CH1 and the second electrical signal CH2 is pi.
In some examples, as shown in fig. 8, the eccentricity error may be calculated based on the second electric signal CH2 at the second moving distance L2 of the oscilloscope 5, and in some examples, the eccentricity error may be calculated by the following formula: and e is an eccentricity error, L is a grating pitch of the grating, and TS is a dynamic range of the phase of the second electrical signal CH2 in the oscilloscope 5, namely, a second moving distance L2. In this case, the eccentricity error can be obtained by using a calculation formula, and whether the eccentricity error meets the requirement or not can be determined. In some examples, the dynamic range of the phase may be the difference between the largest and smallest phase difference of the phase differences of the first and second electrical signals CH1 and CH 2. In some examples, the dynamic range of the phase may refer to a range of the second electrical signal CH2 that reciprocates as it reciprocates in oscilloscope 5.
In some examples, the hub 14, the circular grating 13, and the fastener 15 may remain relatively stationary in step S300.
In some examples, in step S210, the composite structure may be removed and replaced, and step S210 may be performed anew. Here, the composite structure may be formed by combining the boss 14, the circular grating 13 and the fastening member 15, and if the detection result (i.e., the first movement distance L1 or the eccentricity error of the edge of the grating) is not changed, it may be considered that the fastening member 15 stably arranges the circular grating 13 on the boss 14 in step S210.
In some examples, in step S300, the composite structure formed by the hub 14, the circular grating 13, and the fastener 15 may be removed and replaced, and step S300 may be repeated. If the detection result (i.e., the second movement distance L2 or the eccentricity error of the second electrical signal CH 2) is not changed, it can be considered that the fastener 15 stably arranges the circular grating 13 on the hub 14 in step S300.
In some examples, step S200 may be repeatedly performed to make the eccentricity error smaller than a preset threshold. Specifically, if the eccentricity error is not less than the preset threshold, the steps S200 and S300 may be repeated to make the eccentricity error less than the preset threshold. In this case, the eccentricity error can be adjusted by the step S200 a plurality of times, and it can be determined whether the eccentricity error meets the requirement by the step S300 a plurality of times.
In some examples, the preset threshold may be 1 to 10 microns. For example, the preset threshold may be 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, or 10 microns, and preferably, the preset threshold may be 1 micron to 3 microns. In this case, the eccentricity error can be adjusted to 1 to 10 micrometers by step S200, so that the assembly accuracy of the circular grating 13 can be ensured.
In some examples, in step S200, step S300 may be performed simultaneously. In this case, the grating line image of the circular grating 13, the first electric signal CH1, and the second electric signal CH2 can be obtained at the same time, and the eccentricity error of the circular grating 13 can be accurately adjusted.
In step S400, the mounting step may include mounting the circular grating 13 to the grating rotary shaft 12 using a fixing agent, and detaching the fastener 15.
In some examples, the relative position of the circular grating 13 and the grating rotation axis 12 may be fixed if the error is less than a preset threshold.
In some examples, the circular grating 13 may be fixed to the hub 14 by a fixing agent to fix the relative position of the circular grating 13 and the grating rotation axis 12. In this case, since the hub 14 and the grating rotation shaft 12 have high processing accuracy, it is considered that the hub 14 and the grating rotation shaft 12 are overlapped in axial center, and thus the relative position of the circular grating 13 and the grating rotation shaft 12 can be determined by fixing the relative position of the circular grating 13 to the hub 14.
In some examples, the fixing agent may be a hard epoxy resin, and the fastening member 15 is detached after the fixing agent is cured while the circular grating 13 is mounted to the grating rotating shaft 12 using the fixing agent. In this case, the stability of the circular grating 13 with respect to the hub 14 when the fixing agent is cured can be improved.
Various embodiments of the present invention are described above in the detailed description. While these descriptions directly describe the above embodiments, it is to be understood that modifications and/or variations to the specific embodiments shown and described herein may occur to those skilled in the art. Any such modifications or variations that fall within the scope of the present description are intended to be included therein. It is the intention of the inventors that the words and phrases in the specification and claims be given the ordinary and customary meaning to the skilled artisan, unless otherwise indicated.
The foregoing description of various embodiments of the invention known to the applicant at the time of filing has been presented and is intended for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in light of the above teaching. The described embodiments are intended to explain the principles of the invention and its practical application and to enable others skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying out this invention.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings of the present invention, changes and modifications may be made without departing from this invention and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. It will be understood by those within the art that, in general, terms used herein are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.).
Claims (10)
1. A method of assembling a circular grating for an optical device, the method mounting the circular grating to a grating rotation shaft provided on a base, the method comprising: a preparation step of arranging the circular grating on the grating rotating shaft so that the circular grating rotates relative to the base around an axis of the grating rotating shaft as a rotation center; an adjusting step of capturing a grating line image of the circular grating in the process of rotating the circular grating and presenting the grating line image through a display module, and adjusting the relative position of the circular grating and the grating rotating shaft so as to move the edge of one side of the grating line image to a region between a first edge position and a second edge position; a detection step of rotating the circular grating, capturing grating line images of the circular grating at least two positions on the circular grating, converting the grating line images into a first electric signal and a second electric signal, obtaining an eccentricity error of the circular grating based on the first electric signal and the second electric signal, and determining whether the eccentricity error is smaller than a preset threshold value; and an installation step, if the eccentricity error is smaller than the preset threshold, fixing the relative position of the circular grating and the grating rotating shaft.
2. The assembly method according to claim 1, wherein:
in the adjusting step, an edge of one side of the raster image is reciprocally moved between the first edge position and the second edge position during rotation of the circular raster.
3. The assembly method according to claim 1 or 2, characterized in that:
in the adjusting step, when the edge on one side of the raster image is close to the first edge position or the second edge position, the rotation of the circular raster is stopped, and the edge on one side of the raster image is moved to a midpoint between the first edge position and the second edge position by adjusting the relative position of the circular raster and the raster rotation axis.
4. The assembly method of claim 1, wherein:
in the detecting step, the waveform of the first electric signal and the waveform of the second electric signal are presented in such a manner as to fix the waveform of the first electric signal, and the eccentricity error is calculated based on the dynamic range of the phase of the second electric signal.
5. The assembly method according to claim 1, wherein:
in the adjusting step, the relative position of the circular grating and the grating rotating shaft is adjusted in a manner that the center of the circular grating and the axis of the grating rotating shaft are close to each other.
6. The assembly method of claim 1, wherein:
if the eccentricity error is not smaller than the preset threshold, repeating the adjusting step and the detecting step to enable the eccentricity error to be smaller than the preset threshold, wherein the preset threshold is 1-10 micrometers.
7. The assembly method of claim 1, wherein:
in the adjusting step, the detecting step is performed simultaneously.
8. The assembly method of claim 1, wherein:
in the adjusting step, a first sensing module is used for receiving the grid line image of the circular grating and a first display module is used for displaying the grid line image with the grid line.
9. The assembly method of claim 1, wherein:
in the preparing step, the circular grating is disposed to the grating rotation shaft using a fastener and a hub, and a relative position between the circular grating and the grating rotation shaft is made adjustable.
10. The assembly method according to claim 1 or 8, wherein:
in the detecting step, a second sensing module and a third sensing module which are arranged on two opposite sides of the circular grating are respectively used for receiving the grating line image and obtaining the first electric signal and the second electric signal, and an eccentricity error is calculated based on the first electric signal and the second electric signal.
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