CN114706182B - Method for assembling circular grating for optical device - Google Patents
Method for assembling circular grating for optical device Download PDFInfo
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- CN114706182B CN114706182B CN202210270640.9A CN202210270640A CN114706182B CN 114706182 B CN114706182 B CN 114706182B CN 202210270640 A CN202210270640 A CN 202210270640A CN 114706182 B CN114706182 B CN 114706182B
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Abstract
The application provides an assembly 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 axis of the grating rotating shaft as the rotation 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 the grating rotation shaft so that the edge of one side of the grating line image moves between a first edge position and a second edge position; capturing grating images of the circular grating at least two positions, converting the grating images into a first electric signal and a second electric signal, obtaining an eccentric error of the circular grating based on the first electric signal and the second electric signal, and determining whether the eccentric error is smaller than a preset threshold value; and a mounting step, if the eccentric error is smaller than a preset threshold value, fixing the relative positions of the circular grating and the grating rotating shaft. In this case, the relative position between the circular grating and the grating rotation shaft can be adjusted based on the difference between the center of the circular grating and the axis of the grating rotation shaft.
Description
The application is a divisional application of patent application of a method for assembling round grating, the application number of which is 2021, 07, 30 and the application number of which is 2021108683463.
Technical Field
The present application relates generally to laser measuring instruments and, more particularly, to a method of assembling a circular grating for an optical device.
Background
The angular position of the coordinates can be precisely determined by an encoder made of a circular grating, and therefore, the circular grating is commonly used for a laser tracker. Among various error sources affecting the accuracy of the encoder, the eccentricity has a large extent of influence on the accuracy of the encoder, and the extent of influence of the eccentricity on the accuracy of the encoder can be reduced by an appropriate circular grating assembly method.
In the prior art, the surface scribing of the circular grating is utilized to shoot the installation error of the circular grating, and the eccentric amount of the grating disk is obtained based on the surface scribing of the circular grating. For example, CN201910278871.2 discloses a method for correcting angle measurement error of a circular grating sensor based on error source analysis, which uses a CCD camera and a microscope of an eccentric detection device to take image pictures of the surface scribe lines of the circular grating sensor, and performs an image processing method on the right end point coordinates of each scribe line of each image, so as to calculate the eccentric amount and the eccentric angle of the installation grating disk.
However, this method is limited by the accuracy of the image photograph of the reticle of the surface of the grating disk of the circular grating sensor, and it is difficult to meet the requirement of the laser tracker for accuracy.
Disclosure of Invention
The present application has been made in view of the above-described conventional circumstances, and an object of the present application is to reduce an eccentric error when a circular grating is mounted.
To this end, the present application provides an assembling method of a circular grating, the assembling method mounting the circular grating to a grating rotation shaft provided to a base, the grating rotation shaft being configured to be rotatable with respect to the base with an axial center of the grating rotation shaft as a rotation center, the assembling method comprising: a preparation step of arranging the circular grating on the grating rotation shaft so that the circular grating can rotate with respect to the base with an axial center of the grating rotation shaft as a rotation center; an adjustment 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 as to enable the edge of one side of the grating line image to move to be within the dynamic range of the side edge; a detection step of rotating the circular grating, capturing grating images of the circular grating at least two positions on the circular grating, converting the grating images into a first electric signal and a second electric signal, obtaining an eccentric error of the circular grating based on the first electric signal and the second electric signal, and determining whether the eccentric error is smaller than a preset threshold value; and a mounting step, wherein if the eccentric error is smaller than the preset threshold value, the relative positions of the circular grating and the grating rotating shaft are fixed.
In this case, a gap between the center of the circular grating and the axis of the grating rotation shaft can be obtained, and the relative position of the circular grating and the grating rotation shaft can be adjusted based on the gap between the center of the circular grating and the axis of the grating rotation shaft.
In addition, in the assembling method according to the present application, optionally, in the adjusting step, an edge of 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 decentration 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 application, in the adjusting step, if the edge on the side of the grating image is close to the first edge position or the second edge position, the rotation of the circular grating may be stopped, and the edge on the side of the grating image may be moved to a midpoint between the first edge position and the second edge position by adjusting the relative positions of the circular grating and the grating rotation axis. In this case, since the first moving distance of the edge of the grating line is twice the decentration error of the circular grating, the decentration error can be reduced.
In the assembling method according to the present application, in the adjusting step, the relative positions of the circular grating and the grating rotation shaft may be adjusted so that the center of the circular grating and the center of the grating rotation shaft are close to each other. In this case, the decentering error of the circular grating can be reduced.
In addition, in the assembling method according to the present application, optionally, if the decentering error is not smaller than the preset threshold value, the adjusting step and the detecting step are repeated so that the decentering error is smaller than the preset threshold value, the preset threshold value being 1 to 10 micrometers. In this case, the eccentric error can be adjusted by the first detecting step position and the adjusting step a plurality of times, and whether the eccentric error meets the requirement can be judged by a plurality of the second detecting steps, and the eccentric 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 addition, in the assembling method according to the present application, optionally, in the adjusting step, the detecting step is performed simultaneously. In this case, the grating line image, the first electric signal, and the second electric signal of the circular grating can be obtained at the same time, and further the decentering error of the circular grating can be adjusted.
In addition, in the assembling method according to the present application, optionally, 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 a dynamic range of a phase of the second electric signal. In this case, the decentration error of the circular grating can be calculated using the dynamic range of the phase between the first electrical signal and the second electrical signal (i.e., the second moving distance of the waveform of the second electrical signal in the oscilloscope when the first electrical signal is used as a reference).
In addition, in the assembling method according to the present application, the gate line image may be optionally presented by a display module, and an edge of one side of the gate line image is located within a display frame of the display module. In this case, the raster line 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 line image.
In addition, in the assembling method according to the present application, optionally, in the preparing step, the circular grating is arranged to the grating rotation shaft using a fastener and a boss, and a relative position between the circular grating and the grating rotation shaft is made adjustable. In this case, the relative positions of the circular grating and the hub can be fixed by the fastener and the hub, so that the circular grating can be kept stable when rotating relative to the base, and 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 thimble.
In the assembling method according to the present application, the circular grating may be fixed to the hub by a fixing agent in the mounting step, so as to fix the relative positions of the circular grating and the grating rotation axis. In this case, since the hub and the grating rotation shaft have high machining accuracy, the axes of the hub and the grating rotation shaft can be considered to coincide, 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 application can provide an assembling method for reducing an eccentric error when assembling a circular grating.
Drawings
Embodiments of the present application will now be explained in further detail by way of example only with reference to the accompanying drawings.
Fig. 1 is a flow chart schematically showing an assembling method of a circular grating according to an embodiment of the present application.
Fig. 2 is a schematic cross-sectional view showing an axis passing through a grating rotation shaft on which a circular grating according to an embodiment of the present application is mounted.
Fig. 3 is an exploded view showing that the circular grating according to the embodiment of the present application is mounted on the grating rotation shaft.
Fig. 4 is a flowchart showing an adjustment procedure of the method of assembling the circular grating according to the embodiment of the present application.
Fig. 5 is a schematic view showing a scene of a grating obtained in an adjustment step of the method of assembling a circular grating according to the embodiment of the present application.
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 application.
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 of assembling the circular grating according to the embodiment of the present application.
Fig. 8 is a schematic diagram showing the first electric signal and the second electric signal of the second adjustment step of the method of assembling a circular grating according to the embodiment of the present application in an oscilloscope.
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 application belongs. A general guide for many of the terms used in the present application is provided to those skilled in the art. Those 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 application. Indeed, the application is in no way limited to the methods and materials described.
The method for assembling a circular grating for reducing an eccentric error according to the present application is described below with reference to the accompanying drawings.
The application relates to an assembly method of a circular grating for reducing eccentric errors, in particular to an assembly method of a circular grating for a precision optical device. In some examples, the assembly method of the circular grating for reducing the eccentric error according to the present application may also be simply referred to as an assembly method. In some examples, the assembly method of the circular grating for reducing the eccentricity error related to the present application can be used for detecting the eccentricity error. In some examples, the method of assembling a circular grating for reducing eccentricity errors according to the present application may be used to reduce eccentricity errors. In some examples, the eccentricity error may be a radial difference between the center of the circular grating and the axis of the grating rotation shaft.
The assembly method for reducing the eccentric error can respectively measure the radial difference between the center of the circular grating and the axis of the grating rotating shaft by utilizing the first detection step and the detection step, and adjust the relative positions of the circular grating and the grating rotating shaft according to the positions of the edges of the grating line images of the circular grating after the first detection step is finished, so that the eccentric error can be reduced. The method for assembling the circular grating for reducing the eccentric error measures the eccentric error again by using the detection step, and can judge whether the eccentric error meets the requirement under a higher measurement standard because the measurement precision of the detection step is higher than that of the first detection step. Meanwhile, as the assembly method of the circular grating for reducing the eccentric error repeatedly executes the adjustment steps, the influence of the operation error or the systematic error on the eccentric error of the circular grating can be reduced.
In some examples, the method of assembling a circular grating according to the present application may be used to mount the circular grating on a grating rotation axis. In some examples, the circular grating and the grating rotation shaft according to the present application may be applied in precision optical instruments. In some examples, the precision optical instrument may include a laser tracker, a laser interferometer, an electro-optic theodolite, a radar, or an antiaircraft gun director.
In some examples, the circular grating and the grating rotation axis to which the present application relates may be used as an encoder. In this case, the position angle of the auxiliary measuring device can be precisely determined using a circular grating.
Fig. 1 is a flow chart schematically showing a method of assembling the circular grating 13 according to the embodiment of the present application. Fig. 2 is a schematic cross-sectional view showing the axis of the grating rotation shaft 12 through which the circular grating 13 according to the embodiment of the present application is mounted. Fig. 3 is an exploded view showing that the circular grating 13 according to the embodiment of the present application is mounted on 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 rotation shaft 12 by a fastener 15, so that the circular grating 13 is rotatable relative to the base 11 by the grating rotation shaft 12 with the axis of the grating rotation shaft 12 as the rotation center, and the base 11 has a driving device for driving the grating rotation shaft 12 to rotate. In some examples, as shown in fig. 2 and 3, the compound mechanism 1 may be formed by combining the base 11, the grating rotation shaft 12, the hub 14, the circular grating 13, and the fastener 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 shaft 12 by a hub 14, and a geometric center (e.g., a center of a circle) of the hub 14 may be mounted to the grating rotation shaft 12 by the hub 14 and coincide with an axial center of the grating rotation shaft 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 rotation shaft 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 shaft 12 may mean that the radius of the through hole is the same as the radius of the upper end portion of the grating rotation shaft 12. In some examples, the size of the second through hole may match the grating rotation shaft 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 shaft 12. In this case, the hub 14 can be attached to the grating rotation shaft 12, and the hub 14 can be supported by the lower end portion of the grating rotation shaft 12 to rotate the hub 14 around the axis of the grating rotation 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 the axis 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 under the drive of 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 arranged to the hub 14 using a fastener 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 using the set 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 greater than the radius of the second through hole of the hub 14. In this case, the set 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, e.g., 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 clamping arm and the second clamping 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 made adjustable. 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 kept stable when rotated 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 knocking mechanism (described later) or a thimble.
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 also have an adjustment screw (not shown) to adjust the levelness of the base 11. In some examples, the base 11 may have 1, 2, 3, 4, or 5 adjustment screws, preferably, the base 11 may have 3 adjustment screws. In this case, the base 11 can be kept horizontal, and further, the circular grating 13 can be kept horizontal, so that the accuracy of the test of the eccentricity error can be improved.
Fig. 4 is a flowchart showing an adjustment procedure of the method of assembling the circular grating 13 according to the embodiment of the present application. Fig. 5 is a schematic view showing a scene of a grating obtained in an adjustment step of the method of assembling the circular grating 13 according to the embodiment of the present application.
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 a position is adjusted (step S230).
In some examples, in step S200, obtaining a gate line image may be included. In some examples, obtaining the raster line image may be used to initially detect a radial difference between the center of the circular raster 13 and the axis of the raster rotational shaft 12.
In some examples, the raster line image of the circular raster 13 may be captured during rotation of the circular raster 13, and the relative position of the circular raster 13 and the raster rotation axis 12 may be adjusted to move the edge of one side of the raster line image to within the dynamic range of that side edge.
In some examples, as shown in fig. 5, the compound mechanism 1 may be placed in the carrier 2. In some examples, the carrier 2 may include a carrier platform 21, a bracket 22, and a first sensing module 23.
In some examples, the first sensing module 23 may be used to receive the raster line image of the circular raster 13 and the first display module 3 may be used to display the raster line image with raster lines. In other words, the gate line image may be presented through the display module 3, and an edge of one side of the gate line image is located within the display frame of the display module 3. In this case, the raster line 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 line image.
In some examples, the first sensing module 23 may be a charge coupled device camera (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 excellent in vibration resistance, stability in measuring a gate 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 so 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 so that the first sensing module 23 is aligned with an 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 the grid line image having the grid 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 application.
In some examples, the edges of the raster line image may be understood in such a way that the direction of each stripe in the raster line may be the same as the raster line direction of the circular raster 13, the raster line direction of the circular raster 13 may be the same as the radial direction, each stripe in the raster line may have ends, and connecting the ends of the same end of each stripe may result in an edge perpendicular to the direction of the raster line.
In some examples, the edge of the raster line image may be substantially the same shape as the circular raster 13, and the edge of one side of the raster line image may refer to at least a portion of the edge of the raster line image.
In some examples, the first sensing module 23 may be moved to cause the first display module 3 to display an 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 edges of the gate 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 the rotation center under the drive of 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 may be periodically changed. In this case, whether or not the center of the circle grating 13 coincides with the rotation center of the circle grating 13 can be determined based on whether or not the grating line image is periodically changed.
In some examples, after step S210, the dynamic range of the edge of the gate line image may be determined (i.e., step S220).
In some examples, as shown in fig. 6, if the center of the circle grating 13 does not coincide with the rotation center of the circle grating 13, the edge of the grating line image may be periodically moved within a certain range during the rotation of the circle grating 13. Specifically, during the rotation of the circular grating 13, the edge of the grating line image may reciprocate within a certain range.
In some examples, the direction of movement of the edges of the gate lines may be changed by rotating the first sensing module 23.
In some examples, the first edge position a1 and the second edge position a2 of the edge of the gate line in the first display module 3 may be recorded.
In some examples, the first edge position a1 may be any position of the edge of the gate line during the reciprocation. In some examples, the second edge position a2 may be any position of the edge of the gate line different from the first edge position a1 in the course of the reciprocation. In this case, the magnitude of the eccentricity error can be approximately estimated from the distance between the first edge position a1 and the second edge position a2. Preferably, as shown in fig. 6, the first edge position a1 and the second edge position a2 may be at 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 may be rotated relative to the base 11 with the axis center of the grating rotation shaft 12 as the rotation center by the driving of the grating rotation shaft 12, and the edge of the grating line may reciprocate between the first edge position a1 and the second edge position a2. In this case, the first moving distance L1 of the edge of the grating line can be marked, and the decentration 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 area between the first edge position a1 and the second edge position a2.
In some examples, the first movement distance L1 of the edge of the grating line may be twice the decentration error of the circular grating 13. In other words, if the center of the circle 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 eccentric error of the circular grating 13 can be calculated, and it can be determined whether the center of the circle of the circular grating 13 coincides with the rotation center.
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 grating line is located 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 and the grating rotation axis 12 may be changed so that the edge of the grating line moves between the first edge position a1 and the second edge position a2 (i.e., within the dynamic range).
In some examples, a striking mechanism (not shown) may be used to change the relative position of the circular grating 13 and the hub 14, so that the edge of the grating may change in the position of the display device. In this case, the eccentricity error can be adjusted by changing the relative position of the circular grating 13 and the hub 14 to adjust the relative positions of the center of the circle and the center of rotation of the circular grating 13, and the variation of the eccentricity error in moving the circular grating 13 can be determined by the edges of the grating lines.
In some examples, the relative position of the circular grating 13 and the hub 14 may be changed using a fine-tuning translation mechanism (not shown). Specifically, the fine tuning translation mechanism may be mounted on either side of the base 11 through a bracket 22, and may include a push rod and a knob for controlling the movement of the push rod, and the push rod may be directed to the center 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-cartridge. In some examples, the push rod of the fine tuning translation mechanism may be on the line of the center of the circle 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 decentering 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 knocking mechanism or a fine adjustment translation mechanism. The direction in which the knocking mechanism knocks the circular grating 13 or the direction in which the fine adjustment translation mechanism pushes the circular grating 13 may be a direction directed from the first sensing module 23 toward the center of the circle 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 sensor module 23 are collinear when the edge moves to the first edge position a1 or the second edge position a2, the fine adjustment 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, the relative position of the circular grating 13 and the hub 14 can be easily adjusted.
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 hub 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 positions of the circular grating 13 and the grating rotation axis 12 may be changed so that the edges of the grating lines move to the midpoints of the first edge position a1 and the second edge position a2. Specifically, in step S200, if one 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 axis 12. In this case, since the first moving distance L1 of the edge of the grating line is twice the decentering error of the circular grating 13, the decentering error can be reduced.
Fig. 7 is a schematic view showing a scene in which the first electric signal CH1 and the second electric signal CH2 are obtained in the adjustment step of the method of assembling the circular grating 13 according to the embodiment of the present application. Fig. 8 is a schematic diagram showing the first electric signal CH1 and the second electric signal CH2 according to the embodiment of the present application 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 at least two positions on the circular grating 13 passing through the diameter of the circular grating 13 and converted into a first electrical signal CH1 and a second electrical signal CH2, 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 decentration error of the circular grating 13 may be obtained based on the phase difference of the first and second electrical signals CH1 and CH2, and it may be determined whether the decentration error is less than a preset threshold.
In step S300, as shown in fig. 7, the second sensing module 4a and the third sensing module 4b disposed at opposite sides of the circular grating 13 may be used to receive the grating line image and obtain the first electric signal CH1 and the second electric signal CH2, respectively, and the eccentricity error may be calculated based on the first electric signal CH1 and the second electric 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 or not the eccentricity error of the circular grating 13 is reduced at step S200, and it can be determined whether or not the eccentricity error of the circular grating 13 satisfies the requirement.
In some examples, the second sensing module 4a and the third sensing module 4b may be disposed above the circular grating 13 and receive the grating line image. In some examples, the centers of the circles 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 at opposite sides of the circular grating 13, respectively. In this case, two sets of electric signals matched with the opposite sides of the circular grating 13 can be obtained, and since the phase difference of the two sets of electric signals is periodically changed in the case where there is an eccentric error, the eccentric error of the circular grating 13 can be measured.
In some examples, the distance from the second sensing module 4a and the third sensing module 4b to the center of the circle grating 13 may be the same. In some examples, the second sensing module 4a and the third sensing module 4b may be disposed at both ends of the 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, 4b may receive the phase-grid line image and obtain the first and second electrical signals CH1, CH2, respectively. In this case, the first and second electric signals CH1 and CH2 can be obtained, and further the eccentricity error can be obtained using the first and second electric signals CH1 and CH2.
In some examples, the second sensing module 4a and the third sensing module 4b may be photosensors.
In some examples, the second sensing module 4a and the third sensing module 4b may be connected with an oscilloscope 5. In some examples, the second sensing module 4a may be connected to a first channel of the oscilloscope 5 and the third sensing module 4b is connected to a second channel of the oscilloscope 5. In this case, waveforms of the first electric signal CH1 and the second electric signal CH2 can be displayed using two channels of the oscilloscope 5.
In some examples, oscilloscope 5 may be adjusted to cause oscilloscope 5 to display first electrical signal CH1 at rest. In this case, since the center of the circle of the circular grating 13 and the rotation center of the circular grating 13 do not coincide, the phase difference between the first electrical signal CH1 and the second electrical signal CH2 can be periodically changed, and it can be judged whether the center of the circle of the circular grating 13 and the rotation center of the circular grating 13 coincide or not by the second electrical signal CH2 in the case of the oscilloscope 5. Specifically, if the second electric signal CH2 and the first electric signal CH1 are stationary relative to each other, it is considered that the center of the circle of the circular grating 13 and the rotation center of the circular grating 13 overlap each other. If the second electric signal CH2 and the first electric signal CH1 are moved relatively, it is considered that the center of the circle of the circular grating 13 and the rotation center of the circular grating 13 do not overlap.
In some examples, as shown in fig. 8, if the center of the circle grating 13 and the rotation center of the circle grating 13 do not coincide, the phase difference between the first electrical signal CH1 and the second electrical signal CH2 may be periodically changed. In some examples, in step S300, the eccentricity error is calculated 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), and based on the dynamic range of the phase of the second electrical signal CH2. In this case, the eccentricity error of the circular grating 13 can be calculated using the dynamic range of the phase between the first electric signal CH1 and the second electric signal CH2 (i.e., the second moving distance L2 of the waveform of the second electric signal CH2 in the oscilloscope 5 when the first electric signal CH1 is used as a reference).
In some examples, the eccentricity error may be calculated based on the second electrical signal CH2 at the second distance of movement L2 of the oscilloscope 5. For example, the larger the decentering error of the circular grating 13, the larger the second electric signal CH2 is at the second moving distance L2 of the oscilloscope 5. In some examples, the second movement distance L2 of the second electrical signal CH2 on the oscilloscope 5 may be represented by a phase, for example, the second movement 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 calculation formula of the eccentricity error may be: e=l×ts/4/360, where e is the eccentricity error, L is the pitch of the grating, and TS is the dynamic range of the phase of the second electrical signal CH2 in the oscilloscope 5, that is, the second movement distance L2. In this case, the eccentricity error can be obtained by using a calculation formula, and whether the eccentricity error meets the requirement can be determined. In some examples, the dynamic range of the phase may be a difference between a largest phase difference and a smallest phase difference among the phase differences of the first and second electric signals CH1 and CH2. In some examples, the dynamic range of the phase may refer to the range of reciprocation of the second electrical signal CH2 as it reciprocates in the oscilloscope 5.
In some examples, in step S300, the hub 14, the circular grating 13, and the fastener 15 may remain relatively stationary.
In some examples, in step S210, the composite structure may be removed and replaced, and step S210 may be performed again. The composite structure may be formed by combining the hub 14, the circular grating 13 and the fastening member 15, and if the detection result (i.e., the first moving distance L1 of the edge of the grating line or the eccentric error) is not changed, it may be considered that the fastening member 15 stably disposes the circular grating 13 on the hub 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 performed again. If the detection result (i.e., the second moving distance L2 of the second electric signal CH2 or the eccentric error) is not changed, it can be considered that the fastener 15 stably disposes the circular grating 13 on the hub 14 in step S300.
In some examples, step S200 may be repeatedly performed such that the eccentricity error is less than a preset threshold. Specifically, if the decentration error is not less than the preset threshold, the steps S200 and S300 may be repeated such that the decentration error is less than the preset threshold. In this case, the eccentricity error can be adjusted by the step S200 a plurality of times, and it is judged whether or not the eccentricity error meets the requirement by the step S300 a plurality of times.
In some examples, the preset threshold may be 1 micron 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, preferably the preset threshold may be 1 micron to 3 microns. In this case, the eccentric error can be adjusted to 1 to 10 micrometers by step S200, so that the assembling 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 simultaneously obtained, and further 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 rotation shaft 12 using a fixing agent, and removing the fastener 15.
In some examples, if the error is less than a preset threshold, the relative position of the circular grating 13 and the grating rotation axis 12 may be fixed.
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 shaft 12. In this case, since the hub 14 and the grating rotation shaft 12 have high machining accuracy, it is considered that the axes of the hub 14 and the grating rotation shaft 12 overlap, 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, and the fastener 15 is removed after the fixing agent is cured when the circular grating 13 is mounted to the grating rotation shaft 12 using the fixing agent. In this case, the stability of the circular grating 13 with respect to the hub 14 at the time of curing the fixing agent can be improved.
Various embodiments of the present application are described above in the detailed description. While the description directly describes the above embodiments, it should be understood that modifications and/or variations to the specific embodiments shown and described herein will occur to those skilled in the art. Any such modifications or variations that fall within the scope of this specification are intended to be included therein. Unless specifically indicated otherwise, the inventors intend that words and phrases in the specification and claims be given the ordinary and accustomed meaning of a person of ordinary skill.
The foregoing description of various embodiments of the application, which are known to the inventors 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 application to the precise form disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments described are provided to explain the principles of the application and its practical application and to enable others skilled in the art to utilize the application in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, it is intended that the application not be limited to the particular embodiments disclosed for carrying out this application.
While particular embodiments of the present application have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings of this application, changes and modifications may be made without departing from this application 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 application. It will be understood by those within the art that, in general, terms used herein are generally intended to be "open" terms (e.g., the term "comprising" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "comprising" should be interpreted as "including but not limited to," etc.).
Claims (9)
1. A method of assembling a circular grating for an optical device, the method mounting the circular grating to a grating rotation shaft provided at a base, the method comprising: a preparation step of arranging the circular grating on the grating rotation shaft so that the circular grating rotates with respect to the base with an axial center of the grating rotation shaft as a rotation center; an adjustment step of capturing a grating line image of the circular grating in the rotation process of the circular grating, presenting the grating line image through a display module, and adjusting the relative position of the circular grating and the grating rotation shaft when the edge on one side of the grating line image moves to a first edge position or a second edge position so as to enable the edge on one side of the grating line image to move to an area between the first edge position and the second edge position; a detection step of rotating the circular grating, capturing grating images of the circular grating at least two positions on the circular grating, converting the grating images into a first electric signal and a second electric signal, presenting the waveforms of the first electric signal and the second electric signal by using an oscilloscope in a mode of fixing the waveforms of the first electric signal, calculating an eccentric error of the circular grating based on a dynamic range of a phase of the waveform of the second electric signal, and determining whether the eccentric error is smaller than a preset threshold; and a mounting step, wherein if the eccentric error is smaller than the preset threshold value, the relative positions of the circular grating and the grating rotating shaft are fixed.
2. The method of assembly of claim 1, wherein:
in the adjusting step, an edge of one side of the raster image reciprocates 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, if 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 the midpoint between the first edge position and the second edge position by adjusting the relative positions of the circular raster and the raster rotation axis.
4. The method of assembly of claim 1, wherein:
in the adjusting step, the relative positions of the circular grating and the grating rotating shaft are adjusted in a manner that the center of the circular grating and the axis of the grating rotating shaft are close to each other.
5. The method of assembly of claim 1, wherein:
and if the eccentricity error is not smaller than the preset threshold, repeating the adjusting step and the detecting step so that the eccentricity error is smaller than the preset threshold, wherein the preset threshold is 1-10 microns.
6. The method of assembly of claim 1, wherein:
in the adjusting step, the detecting step is performed simultaneously.
7. The method of assembly of claim 1, wherein:
in the adjusting step, a first sensing module is used for receiving the grating line image of the circular grating and a first display module is used for displaying the grating line image with the grating lines.
8. The method of assembly of claim 1, wherein:
in the preparing step, the circular grating is arranged 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.
9. The assembly method according to claim 1 or 7, characterized in that:
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, obtaining the first electric signal and the second electric signal, and calculating an eccentric error based on the first electric signal and the second electric signal.
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| JP2002288863A (en) * | 2001-03-27 | 2002-10-04 | Sony Corp | Optical pickup and disk-driving device |
| CN1424594A (en) * | 2001-12-11 | 2003-06-18 | 中国科学院光电技术研究所 | Method for forming gratings by laser direct writing device |
| CN202382724U (en) * | 2011-12-30 | 2012-08-15 | 北京中科恒业中自技术有限公司 | Angle measuring instrument |
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