Alignment device and alignment method

Abstract

The invention discloses an alignment device and an alignment method, and belongs to the technical field of electronic equipment. The graph card is located on one side of the light source, and the graph card is provided with a through hole array; the displacement table assembly comprises a first displacement table which is located on the side, away from the light source, of the image card, and the first displacement table is used for bearing the image sensor and adjusting the position of the image sensor according to an MTFmap imaged by the image sensor; the second displacement table is located on the side, away from the light source, of the graphic card, the first displacement table is arranged on the second displacement table, and the second displacement table is used for bearing the lens and adjusting the position of the lens.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic devices, and in particular relates to an alignment device and an alignment method. BACKGROUND

[0002] The structural design of the camera module of an electronic device is extremely compact. Due to the limitation of space and size, the design tolerance redundancy of each lens in the lens is very small, and the assembly tolerance redundancy between the entire lens and the image sensor is also very small.

[0003] In the related art, in order to improve the precision of the camera module, modulation transfer function (MTF) alignment is usually used for assembly, that is, when assembling the camera module, the MTF of the imaging of the image sensor is obtained, and the alignment effect of the lens and the image sensor is determined according to the MTF.

[0004] At present, the assembly of the camera module usually uses a cross wire as a target or uses a checkerboard as a target to test the modulation transfer function. However, such a method can only obtain the MTF in a specific direction, and cannot obtain the distribution map of the MTF symmetrical with the optical axis, thereby affecting the assembly precision and assembly efficiency of the camera module. SUMMARY

[0005] The present application aims to provide an alignment device and an alignment method, which can solve the technical problem of low assembly precision and assembly efficiency of the lens and the image sensor of an electronic device.

[0006] In a first aspect, the present application provides an alignment device, comprising:

[0007] a light source;

[0008] a chart located on one side of the light source, the chart being provided with an array of through holes;

[0009] a displacement table assembly, the displacement table assembly comprising:

[0010] a first displacement table located on the side of the chart away from the light source, the first displacement table being used to carry an image sensor and adjust the position of the image sensor according to the MTF map of the imaging of the image sensor;

[0011] a second displacement table located on the side of the chart away from the light source, the first displacement table being arranged on the second displacement table, and the second displacement table being used to carry a lens and adjust the position of the lens.

[0012] In a second aspect, the present application provides an alignment method, which is executed by an alignment device, the first displacement table of the alignment device carrying an image sensor, and the second displacement table of the alignment device carrying a lens, the alignment method comprising:

[0013] controlling the light source of the alignment device to emit light;

[0014] generating an MTF map according to the imaging of the image sensor;

[0015] determining, according to the MTF map, an MTF(Xcut) curve of a tangent passing through the center of the MTF map and along a first direction, and an MTF(Ycut) curve of a tangent passing through the center of the MTF map and along a second direction, the first direction and the second direction being perpendicular to each other;

[0016] controlling the displacement stage assembly to move until the MTF(Xcut) curve satisfies a first condition, the MTF(Ycut) curve satisfies a second condition, and the center of gravity of the MTF map coincides with the center of the imaging of the image sensor;

[0017] wherein the first condition is that the absolute value of a first difference value between a first length and a second length belongs to a first interval, the first length is a distance between a first point and a first median line on the MTF(Xcut) curve, the second length is a distance between a second point and the first median line on the MTF(Xcut) curve, the first point and the second point are two points with the same height on the MTF(Xcut) curve;

[0018] the second condition is that the absolute value of a second difference value between a third length and a fourth length belongs to a second interval, the third length is a distance between a third point and a second median line on the MTF(Ycut) curve, the fourth length is a distance between a fourth point and the second median line on the MTF(Ycut) curve, the third point and the fourth point are two points with the same height on the MTF(Ycut) curve.

[0019] The alignment device provided by the application comprises a light source, a chart and a displacement stage assembly, the displacement stage assembly comprises a first displacement stage and a second displacement stage, the chart is located on one side of the light source, the first displacement stage is arranged on the second displacement stage, the second displacement stage can move with the first displacement stage, the second displacement stage is located on the side of the chart away from the light source, the first displacement stage is used for carrying an image sensor, and the second displacement stage is used for carrying a lens.

[0020] The chart is provided with a through hole array, and then when the image sensor and the lens are aligned, the light source emits light, the light source forms an image on the image sensor through the through hole array of the chart, and due to the symmetry of the through hole array, the MTF map formed during the alignment of the image sensor and the lens is also symmetrical about the optical axis, so that the alignment state of the image sensor and the lens can be better distinguished, and the alignment speed and the alignment precision of the image sensor and the lens are improved.

[0021] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the attendant drawings or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0022] The foregoing and / or additional aspects and advantages of the application will become apparent to those skilled in the art from the following description, which proceeds with reference to the accompanying drawings.

[0023] Figure 1 is a schematic diagram of an alignment device according to embodiments of the application;

[0024] Figure 2 is a schematic diagram of a chart in an alignment device according to embodiments of the application;

[0025] Figure 3 is a schematic diagram of placing an image sensor and a lens on an alignment device according to embodiments of the application;

[0026] Figure 4 is one of flowcharts of an alignment method according to embodiments of the application;

[0027] Figure 5 is an MTF map when an image sensor and a lens are in an aligned state in an alignment method according to embodiments of the application;

[0028] Figure 6 is a schematic diagram of a center of gravity of an MTF map and a center position of imaging when an image sensor and a lens are in an aligned state in an alignment method according to embodiments of the application;

[0029] Figure 7 is an MTF map when an image sensor and a lens are not in an aligned state in an alignment method according to embodiments of the application;

[0030] Figure 8 is a schematic diagram of a center of gravity of an MTF map and a center position of imaging when an image sensor and a lens are not in an aligned state in an alignment method according to embodiments of the application;

[0031] Figure 9 is an MTF(Xcut) curve when an image sensor and a lens are not in an aligned state in an alignment method according to embodiments of the application;

[0032] Figure 10 is an MTF(Ycut) curve when an image sensor and a lens are not in an aligned state in an alignment method according to embodiments of the application;

[0033] Figure 11 is imaging of an image sensor in an alignment method according to embodiments of the application;

[0034] Figure 12is a schematic diagram of determining the sector area of each via hole in the imaging of the image sensor in the alignment method according to the embodiment of the present application;

[0035] Figure 13 is a schematic diagram of the process from the imaging of the image sensor to the calculation of the MTF in the alignment method according to the embodiment of the present application;

[0036] Figure 14 is a flowchart of the alignment method according to the embodiment of the present application;

[0037] Figure 15 is a flowchart of sub-cycle 1 in the alignment method according to the embodiment of the present application;

[0038] Figure 16 is a flowchart of sub-cycle 2 in the alignment method according to the embodiment of the present application;

[0039] Figure 17 is a flowchart of sub-cycle 3 in the alignment method according to the embodiment of the present application;

[0040] Figure 18 is an MTF curve in the focusing process in the alignment method according to the embodiment of the present application;

[0041] Figure 19 is an MTF map graph when misalignment in the alignment method according to the embodiment of the present application;

[0042] Figure 20 is an MTF map graph after angle adjustment in the alignment method according to the embodiment of the present application;

[0043] Figure 21 is an MTF map graph after adjustment in the alignment method according to the embodiment of the present application.

[0044] Reference signs:

[0045] 1 alignment device, 11 light source, 12 chart, 121 via hole array, 13 displacement table assembly, 131 first displacement table, 132 second displacement table, 2 image sensor, 3 lens. DETAILED DESCRIPTION

[0046] The embodiments of the present application will be described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts, fall within the scope of protection of the present application.

[0047] The terms "first", "second" in the description and claims of the present application can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in a "or" relationship.

[0048] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0049] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] The following will be described in conjunction with Figures 1 to 21 The alignment device 1 and the alignment method according to the embodiments of the present application are described.

[0051] In the first aspect, as shown in Figure 1 , Figure 2 and Figure 3 The present application provides an alignment device 1, comprising: a light source 11; a picture card 12 located on one side of the light source 11, the picture card 12 being provided with an array of through holes 121; a displacement table assembly 13, the displacement table assembly 13 comprising: a first displacement table 131 located on the side of the picture card away from the light source 11, the first displacement table 131 being used to carry an image sensor 2 and adjust the position of the image sensor 2 according to the MTF map of the imaging of the image sensor 2; a second displacement table 132 located on the side of the picture card away from the light source 11, the first displacement table 131 being arranged on the second displacement table 132, the second displacement table 132 being used to carry a lens 3 and adjust the position of the lens 3.

[0052] The alignment device 1 provided in the application comprises a light source 11, a chart 12 and a displacement table assembly 13, the displacement table assembly 13 comprises a first displacement table 131 and a second displacement table 132, the chart 12 is located on one side of the light source 11, the first displacement table 131 is arranged on the second displacement table 132, the second displacement table 132 can move with the first displacement table 131, the second displacement table 132 is located on the side of the chart 12 away from the light source 11, the first displacement table 131 is used for carrying an image sensor 2, and the second displacement table 132 is used for carrying a lens 3.

[0053] In the application, the chart 12 is provided with a through hole array 121, and then the light source 11 emits light during the alignment operation of the image sensor 2 and the lens 3, the light source 11 forms an image on the image sensor 2 through the through hole array 121 of the chart 12, and due to the symmetry of the through hole array 121, the MTFmap image formed during the alignment of the image sensor 2 and the lens 3 is also symmetrical about the optical axis, so that the alignment state of the image sensor 2 and the lens 3 can be better distinguished, and the alignment speed and alignment accuracy of the image sensor 2 and the lens 3 are improved. The MTFmap image is a two-dimensional image composed of the value of each circular position meridian MTF or sagittal MTF at a selected spatial frequency.

[0054] In the application, the first displacement table 131 and the second displacement table 132 can act independently or cooperatively, so that the relative position and angle of the image sensor 2 and the lens 3 can be adjusted.

[0055] The second displacement table 132 can simultaneously adjust the positions of the first displacement table 131 and the lens 3, so that the centers of the lens 3, the image sensor 2 and the chart 12 can be aligned.

[0056] According to some embodiments of the application, each through hole in the through hole array 121 is circular and has the same diameter, and during the alignment operation of the image sensor 2 and the lens 3, a partial fan-shaped region of the imaging of the through hole is taken, and the fan-shaped region is used to generate the MTFmap image.

[0057] Specifically, each through hole in the through hole array 121 is circular and has the same diameter, and then each through hole is the same in the imaging of the through hole array 121 on the image sensor 2.

[0058] During the alignment operation of the image sensor 2 and the lens 3, the imaging fan-shaped region of the through hole is determined according to the center of the imaging of the through hole, the center of the imaging of the image sensor 2 and the angle range, as shown in Figure 11 The imaging of the image sensor 2 is the image of a plurality of through hole arrays 121, as shown in Figure 3 and Figure 12 Before the MTFmap image is determined, the required image is determined first, and the included angle w between the connecting line of the center of each through hole and the imaging center and the X axis is calculated.

[0059] As shown in Figure 12 After the angle w is determined, a certain angle range wb is selected to obtain a sector area, and the selection of the sector area is based on the angle w = arctan(x ÷ y) calculated for each through hole, and the radius wherein x represents the coordinate of the X-axis of the center of the through hole, y represents the coordinate of the Y-axis of the circle of the through hole, the angle span of the entire sector area is w' ∈ [w-wb, w+wb], and wb is a set value, which can be any value between 10 degrees and 15 degrees.

[0060] When the image sensor 2 and the lens are aligned, the MTF map obtained by the above process is a regular and central pattern, so that the MTF map is more convenient to identify, and it is better to judge whether the image sensor 2 and the lens 3 are aligned, and the alignment speed and accuracy of the image sensor 2 and the lens 3 are improved.

[0061] As shown in Figure 1 and Figure 2 According to some embodiments of the present application, the diameter of the through hole in the through hole array 121 is greater than or equal to one-third of the center distance of the adjacent through holes in the same row or column, and less than or equal to one-half of the center distance of the adjacent through holes in the same row or column.

[0062] Specifically, the diameter of the through hole in the through hole array 121 is greater than or equal to one-third of the center distance of the adjacent through holes in the same row or column, and less than or equal to one-half of the center distance of the adjacent through holes in the same row or column, thereby reducing the non-transparent area in the through hole array 121, facilitating the miniaturization of the chart 12, and reducing the mutual interference between the imaging of the through holes, and the imaging of each through hole is clear.

[0063] As shown in Figure 1 and Figure 2 According to some embodiments of the present application, the center of the chart 12 is provided with a through hole in the through hole array 121, and the through hole array 121 is arranged in axial symmetry with a straight line passing through the center of the chart 12.

[0064] Specifically, the center of the chart 12 is provided with a through hole in the through hole array 121, and the through hole array 121 is arranged in axial symmetry with a straight line passing through the center of the chart 12, so that when the image sensor 2 and the lens 3 are aligned, the center of the imaging of the image sensor 2 and the center of gravity of the MTF map coincide, thereby providing a standard for the alignment of the image sensor 2 and the lens 3.

[0065] As shown in Figure 1 and Figure 2As shown, according to some embodiments of the present application, the number of rows of the via array 121 is 2N+1; the number of columns of the via array 121 is 2N+1; wherein N is a positive integer, and N is greater than or equal to 4.

[0066] Specifically, the number of rows of the via array 121 is 2N+1, and the number of columns of the via array 121 is 2N+1, wherein N is a positive integer, and N is greater than or equal to 4, that is, the number of rows of the via array 121 is an odd number greater than or equal to 9, the number of columns of the via array 121 is an odd number greater than or equal to 9, and the number of rows and the number of columns of the via array 121 are equal, so that the number of vias in the via array 121 is large, and the via in the middle of the via array 121 is located at the center of gravity of the card 12.

[0067] As shown in Figure 1 and Figure 2 According to some embodiments of the present application, the card 12 is made of opaque material, that is, light can only propagate to the lens 3 through the via array 121 on the card 12.

[0068] As shown in Figure 1 and Figure 2 According to some embodiments of the present application, the first displacement table 131 and the second displacement table 132 are both six-axis displacement tables.

[0069] As shown in Figure 1 According to some embodiments of the present application, the card 12 is a square flat plate made of opaque matte black material, and a circular via array 121 is opened on the flat plate. All vias are distributed at equal intervals, the number of columns is 2N+1, the number of rows is 2N+1, N is a positive integer, N is greater than or equal to 4, the diameter of the via is less than one-half of the interval between adjacent vias, and the diameter of the via is greater than one-third of the interval between adjacent vias.

[0070] As shown in Figure 3 The card 12 is illuminated using the LED homogenizing light source 11. The lens 3 is placed on the second displacement table 132, the image sensor 2 is placed on the first displacement table 131, the first displacement table 131 carrying the image sensor 2 is placed on the second displacement table 132, and the first displacement table 131 can adjust the relative position with the second displacement table 132. The first displacement table 131 is mainly used for active alignment adjustment between the image sensor 2 and the lens 3, and the second displacement table 132 is mainly used for aligning the center of the entire camera module including the lens 3 and the image sensor 2 with the card 12.

[0071] The second aspect, Figure 4 is one of the flowcharts of the alignment method according to the embodiments of the present application. The alignment method is executed by an alignment device, the first displacement table of the alignment device carries an image sensor, and the second displacement table of the alignment device carries a lens, as Figure 4As shown, the alignment method provided by one embodiment of the present application has the following process:

[0072] Step 402: control the light source of the alignment device to emit light;

[0073] Step 404: generate an MTF map according to the imaging of the image sensor;

[0074] Step 406: determine an MTF(Xcut) curve of a tangent Xcut passing through the center of the MTF map and along a first direction, and an MTF(Ycut) curve of a tangent Ycut passing through the center of the MTF map and along a second direction, according to the MTF map, the first direction and the second direction being perpendicular to each other;

[0075] Step 408: control the displacement stage assembly to move until the MTF(Xcut) curve satisfies a first condition, the MTF(Ycut) curve satisfies a second condition, and the center of gravity of the MTF map coincides with the center of the imaging of the image sensor.

[0076] The first condition is that the absolute value of a first difference value belongs to a first interval, the absolute value of the first difference value being the difference between a first length and a second length, the first length being the distance between a first point and a first middle line on the MTF(Xcut) curve, and the second length being the distance between a second point and the first middle line on the MTF(Xcut) curve, the first point and the second point being two points of equal height on the MTF(Xcut) curve; and the second condition is that the absolute value of a second difference value belongs to a second interval, the absolute value of the second difference value being the difference between a third length and a fourth length, the third length being the distance between a third point and a second middle line on the MTF(Ycut) curve, and the fourth length being the distance between a fourth point and the second middle line on the MTF(Ycut) curve, the third point and the fourth point being two points of equal height on the MTF(Ycut) curve.

[0077] The alignment method provided by the present application is performed by the alignment device, the first displacement stage of the alignment device carries the image sensor, the second displacement stage of the alignment device carries the lens, the image sensor, the lens, the chart and the light source are arranged in sequence, and the alignment method comprises: controlling the light source of the alignment device to emit light, so that the light passes through the through hole array of the chart and is irradiated on the image sensor through the lens.

[0078] For convenience of representation, a coordinate system is established based on the alignment device, the first direction is the X axis, the second direction is the Y axis, the third direction is the Z axis, the a direction is around the first direction, the b direction is around the second direction, and the c direction is around the third direction, the first direction and the second direction are directions parallel to the chart, and the third direction is a direction perpendicular to the chart.

[0079] acquire the imaging of the image sensor, and generate a MTFmap graph according to the imaging of the image sensor, then determine a MTF(Xcut) curve of a tangent Xcut passing through the center of the MTFmap graph and along a first direction, and a MTF(Ycut) curve of a tangent Ycut passing through the center of the MTFmap graph and along a second direction according to the MTFmap graph.

[0080] wherein two points of the same height position are selected in the MTF(Xcut) curve, which are a first point and a second point respectively, a first middle line of the MTF(Xcut) curve is determined, the first point and the second point are located on two sides of the first middle line respectively, then a distance between the first point and the first middle line is determined, that is, a perpendicular line is drawn from the first point to the first middle line, and the length of the perpendicular line is the first length; a distance between the second point and the first middle line is determined, that is, a perpendicular line is drawn from the second point to the first middle line, and the length of the perpendicular line is the second length.

[0081] an absolute value of a first difference value of the first length and the second length is determined, in the case that the absolute value of the first difference value belongs to a first interval set in advance, it indicates that the angle of the image sensor and the lens around the first direction is in an aligned state.

[0082] Similarly, two points of the same height position are selected in the MTF(Ycut) curve, which are a third point and a fourth point respectively, a second middle line of the MTF(Ycut) curve is determined, the third point and the fourth point are located on two sides of the second middle line respectively, then a distance between the third point and the second middle line is determined, that is, a perpendicular line is drawn from the third point to the second middle line, and the length of the perpendicular line is the third length; a distance between the fourth point and the second middle line is determined, that is, a perpendicular line is drawn from the fourth point to the second middle line, and the length of the perpendicular line is the fourth length.

[0083] an absolute value of a second difference value of the third length and the fourth length is determined, in the case that the absolute value of the second difference value belongs to a second interval set in advance, it indicates that the angle of the image sensor and the lens around the second direction is in an aligned state.

[0084] and in the case that the center of the MTFmap graph and the center of the imaging of the image sensor coincide, it indicates that the center of the image sensor and the optical axis of the lens are aligned.

[0085] Through the limitation of the three conditions, the alignment operation of the image sensor and the lens is realized, and the alignment speed and the alignment accuracy of the image sensor and the lens are improved.

[0086] And, the chart is provided with a through-hole array, and further, when the image sensor and the lens are aligned, the light source emits light, the light source is imaged on the image sensor through the through-hole array of the chart, and due to the symmetry of the through-hole array, the distribution diagram of the MTF of the imaging is also axially symmetric when the image sensor and the lens are aligned, so that the alignment state of the image sensor and the lens is better distinguished, and the alignment speed and alignment accuracy of the image sensor and the lens are improved.

[0087] As shown in Figure 5 and Figure 6 , the MTFmap diagram calculated under the condition that there is no angle and position offset between the image sensor and the lens is a two-dimensional diagram composed of the value of the meridian MTF or the sagittal MTF at each circular position at a selected spatial frequency, and the number is between 0 and 1. Theoretically, if there is no tolerance, it is rotationally symmetric along the optical axis. The center of gravity of the MTFmap diagram coincides with the center of imaging.

[0088] As shown in Figure 7 and Figure 8 , the MTFmap diagram calculated under the condition that there is an angle and position offset between the image sensor and the lens is a two-dimensional diagram composed of the value of the meridian MTF or the sagittal MTF at each circular position at a selected spatial frequency, and the number is between 0 and 1. The center of gravity of the MTFmap diagram is misaligned with the center of imaging.

[0089] As shown in Figure 7 , Xcut is a tangent line passing through the center along the X-axis on the MTFmap diagram, Ycut is a tangent line passing through the center along the Y-axis on the MTFmap diagram, Figure 9 a MTF(Xcut) curve is shown, Figure 10 a MTF(Ycut) curve is shown.

[0090] According to some embodiments of the present application, the first displacement table is controlled to move until the MTF(Xcut) curve meets the first condition, the MTF(Ycut) curve meets the second condition, and the center of gravity of the MTFmap diagram coincides with the center of imaging of the image sensor, comprising: controlling the first displacement table to rotate until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition; controlling the first displacement table to move until the center of gravity of the MTFmap diagram coincides with the center of imaging of the image sensor; wherein, during the movement of the first displacement table, in the case that the MTF(Xcut) curve no longer meets the first condition or the MTF(Ycut) curve no longer meets the second condition, the first displacement table is controlled to rotate until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition.

[0091] Specifically, the first displacement table is controlled to move until the MTF(Xcut) curve meets the first condition, the MTF(Ycut) curve meets the second condition, and the center of gravity of the MTFmap graph coincides with the center of imaging of the image sensor, including: first, the first displacement table is controlled to rotate to adjust the relative angle of the image sensor and the lens until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition; then, the first displacement table is controlled to move to adjust the relative position of the image sensor and the lens until the center of gravity of the MTFmap graph coincides with the center of imaging of the image sensor; and during the movement of the first displacement table, the MTF(Xcut) curve and the MTF(Ycut) curve are continuously detected, and if the MTF(Xcut) curve no longer meets the first condition or the MTF(Ycut) curve no longer meets the second condition due to the movement of the image sensor and the lens being too large, the first displacement table is controlled to rotate again to adjust the relative angle of the image sensor and the lens until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition.

[0092] That is, the adjustment of the image sensor and the lens is divided into two stages of rotation and movement, and the angle and position of the image sensor relative to the lens are adjusted respectively, so as to reduce the adjustment difficulty of the image sensor and the lens alignment operation and improve the efficiency of the image sensor and the lens alignment operation.

[0093] As shown in Figure 11 , the imaging of the image sensor is the image of a plurality of hole arrays, as shown in Figure 3 and Figure 12 , before determining the MTFmap graph, the required image is determined first, and the angle w between the connecting line of the center of each hole and the imaging center and the X axis is calculated, that is, the orientation angle of the meridian MTF or the sagittal MTF of each hole.

[0094] As shown in Figure 12 , after determining the angle w, a certain angle range wb is selected to obtain a sector region, and the sector region is selected according to the angle w=arctan(x÷y) calculated for each hole and the radius , wherein x represents the X-axis coordinate of the center of the hole, y represents the Y-axis coordinate of the hole, and the angle span of the entire sector region is w'∈[w-wb, w+wb], wb can be equal to a set value between 10 degrees and 15 degrees.

[0095] As shown in Figure 13As shown, after the imaging of the image sensor is obtained, the region of interest (ROI) selection is performed first, the imaging of a through hole is selected, then the sector region of the imaging of the through hole is selected, then the edge detection is performed on the sector region, after the edge is determined, the effective pixel extraction is performed, after the effective pixels of all the imaging of the through hole are extracted, the edge spread function is calculated, then the MTF is calculated, and then the determination of the MTF map is performed.

[0096] According to some embodiments of the present application, the displacement table assembly is controlled to rotate until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition, including: controlling the displacement table assembly to rotate one step around the first direction; in the case that the absolute value of the first difference value in the MTF(Xcut) curve belongs to the first interval, determining that the step length of the next rotation around the first direction is 0; in the case that the absolute value of the first difference value in the MTF(Xcut) curve is less than the lower limit value of the first interval, determining that the step length of the next rotation around the first direction is the first step length; in the case that the absolute value of the first difference value in the MTF(Xcut) curve is greater than the upper limit value of the first interval, determining that the step length of the next rotation around the first direction is the negative first step length; the displacement table assembly is controlled to rotate until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition, including: controlling the displacement table assembly to rotate one step around the second direction; in the case that the absolute value of the second difference value in the MTF(Xcut) curve belongs to the second interval, determining that the step length of the next rotation around the second direction is 0; in the case that the absolute value of the second difference value in the MTF(Xcut) curve is less than the lower limit value of the second interval, determining that the step length of the next rotation around the second direction is the second step length; in the case that the absolute value of the second difference value in the MTF(Xcut) curve is greater than the upper limit value of the second interval, determining that the step length of the next rotation around the second direction is the negative second step length.

[0097] Specifically, the displacement stage assembly is controlled to rotate until the MTF(Xcut) curve meets the first condition and the MTF(Ycut) curve meets the second condition. This includes: first, controlling the displacement stage assembly to rotate one step around the first direction; then, determining the relationship between the absolute value of the first difference and the first interval in the new MTF(Xcut) curve. If the absolute value of the first difference in the MTF(Xcut) curve belongs to the first interval, no further adjustment is needed, and the next step size for rotation around the first direction is determined to be 0. If the absolute value of the first difference in the MTF(Xcut) curve is less than the lower limit of the first interval, it indicates that rotation in the current direction should continue, and therefore, the next step size for rotation around the first direction is determined to be the first step size. If the absolute value of the first difference in the MTF(Xcut) curve is greater than the upper limit of the first interval, it indicates that rotation in the opposite direction should be performed, and therefore, the next step size for rotation around the first direction is determined to be the negative first step size.

[0098] First, control the displacement stage assembly to rotate one step around the second direction. Then, determine the relationship between the absolute value of the second difference and the second interval in the new MTF(Ycut) curve. If the absolute value of the second difference in the MTF(Ycut) curve belongs to the second interval, no further adjustment is needed, and the next step size for rotation around the second direction is determined to be 0. If the absolute value of the second difference in the MTF(Ycut) curve is less than the lower limit of the second interval, it indicates that the rotation in the current direction should continue. Therefore, the next step size for rotation around the second direction is determined to be the second step size. If the absolute value of the second difference in the MTF(Ycut) curve is greater than the upper limit of the second interval, it indicates that the rotation in the opposite direction should be performed. Therefore, the next step size for rotation around the second direction is determined to be a negative second step size.

[0099] like Figure 14 As shown, Figure 14 This is a second flowchart of the alignment method according to an embodiment of this application, such as... Figure 14 As shown, the flow of an alignment method provided in one embodiment of this application is as follows:

[0100] Step 1402: Loading materials;

[0101] Step 1404: The first displacement stage moves to adjust the Z-axis displacement of the image sensor for rough focusing;

[0102] Step 1406: The first displacement stage moves to adjust the angle of the image sensor at points a and b;

[0103] Step 1408: Is dTilta = 0 & dTiltb = 0? If yes, proceed to step 1410; otherwise, proceed to step 1406.

[0104] Step 1410: the first displacement table is actuated to adjust the displacement of the image sensor in X and Y;

[0105] Step 1412: whether dShiftX=0&dShiftY=0; if yes, step 1420 is executed, and if no, step 1414 is executed;

[0106] Step 1414: whether dTilta=0&dTiltb=0; if yes, step 1418 is executed, and if no, step 1416 is executed;

[0107] Step 1416: the first displacement table is actuated to adjust the angle of the image sensor in a and b;

[0108] Step 1418: the first displacement table is actuated to adjust the displacement of the image sensor in X and Y;

[0109] Step 1420: end.

[0110] Wherein, & represents and.

[0111] The alignment method provided in the application, when executed by the alignment device, first adjusts the angle of the image sensor relative to the lens for the first displacement table, and then adjusts the position of the image sensor relative to the lens, and in the process of adjusting the position of the image sensor relative to the lens, the angle of the image sensor relative to the lens is also adjusted, so as to realize the alignment of the angle and position of the image sensor relative to the lens.

[0112] As shown in Figure 9 , H1=(Max1+Min1)÷2, H1 represents the height of the first point and the second point, Max1 represents the maximum value of the MTF(Xcut) curve, and Min1 is the minimum value of the MTF(Xcut) curve, as shown in Figure 10 , H2=(Max2+Min2)÷2, H2 represents the height of the third point and the fourth point, Max2 represents the maximum value of the MTF(Ycut) curve, and Min2 is the minimum value of the MTF(Ycut) curve.

[0113] Figure 15 is a flowchart of sub-cycle 1 in the alignment method according to the embodiments of the application, as shown in Figure 15 , the flow of sub-cycle 1 in the alignment method provided in an embodiment of the application is as follows:

[0114] Step 1502: the first displacement table is initially actuated, dTilta0=tilt_stepa0>0, tilt_stepa0=0.04 degrees;

[0115] Step 1504: Compare |Xright-Xleft| and |Xright_init-Xleft_init|;

[0116] Step 1506: dTilta = tilt_stepa0;

[0117] Step 1508: dTilta = 0;

[0118] Step 1510: dTilta = -tilt_stepa0;

[0119] Step 1512: dTilta = 0? If yes, go to Step 1538, otherwise go to Step 1514;

[0120] Step 1514: dTilta0 x dTilta < 0? If yes, go to Step 1516, otherwise go to Step 1518;

[0121] Step 1516: tilt_stepa0 = tilt_stepa0 ÷ 2;

[0122] Step 1518: dTilta0 = dTilta;

[0123] Step 1520: First displacement stage initial movement, dTiltb0 = tilt_stepb0 > 0, tilt_stepb0 = 0.04 degrees;

[0124] Step 1522: Compare |Yright-Yleft| and |Yright_init-Yleft_init|;

[0125] Step 1524: dTiltb = tilt_stepb0;

[0126] Step 1526: dTiltb = 0;

[0127] Step 1528: dTiltb = -tilt_stepb0;

[0128] Step 1530: dTiltb = 0? If yes, go to Step 1538, otherwise go to Step 1532;

[0129] Step 1532: dTiltb0 x dTiltb < 0? If yes, go to Step 1534, otherwise go to Step 1536;

[0130] Step 1534: tilt_stepb0 = tilt_stepb0 ÷ 2;

[0131] Step 1536: dTiltb0 = dTiltb;

[0132] Step 1538: Check if dTilta=0 & dTiltb=0;

[0133] Step 1540: Exit sub-loop 1.

[0134] like Figure 9 As shown, Xleft is the first length during the image sensor adjustment process, Xright is the second length during the image sensor adjustment process, Xleft_init is the first length when the image sensor and lens are aligned, and Xright_init is the second length when the image sensor and lens are aligned. dTilta represents the adjustment step size of the stage assembly along the direction a, and dTilta0 represents the initial adjustment step size, for example, dTilta0 = tilt_stepa0, which is 0.04 degrees. In the initial case, it may be unclear whether the change of a will affect the image sensor imaging. The first stage can be initially precessed by one step, and the relative magnitude of the absolute value |Xright-Xleft| and the absolute value |Xright_init-Xleft_init| can be used to determine this. The above process is defined as sub-loop 1.

[0135] like Figure 10 As shown, Yleft is the third length during the image sensor adjustment process, Yright is the fourth length during the image sensor adjustment process, Xleft_init is the third length in the image sensor and lens alignment state, and Xright_init is the fourth length in the image sensor and lens alignment state. dTiltb represents the adjustment step size of the displacement stage component along the b direction, and dTiltb0 represents the initial adjustment step size, for example, dTiltb0 = tilt_stepb0 is 0.04 degrees. In the initial case, the impact of the change in b on the image sensor imaging may not be clear. The first displacement stage can initially precess one step, and the relative magnitude of the absolute value |Yright-Yleft| and the absolute value |Yright_init-Yleft_init| can be used to determine the impact. The above process is defined as sub-loop 1.

[0136] Figure 16 This is a flowchart of sub-loop 2 in the alignment method according to an embodiment of this application, as follows: Figure 16 As shown, the flow of sub-loop 2 in the alignment method provided in one embodiment of this application is as follows:

[0137] Step 1602: The first displacement stage uses tilt_stepa0 from the previous step;

[0138] Step 1604: Compare |Xright - Xleft| and |Xright_init - Xleft_init|;

[0139] Step 1606: dTilta = tilt_stepa0;

[0140] Step 1608: dTilta = 0;

[0141] Step 1610: dTilta = -tilt_stepa0;

[0142] Step 1612: dTilta = 0? If yes, go to Step 1638, else go to Step 1614;

[0143] Step 1614: dTilta 0 x dTilta < 0? If yes, go to Step 1616, else go to Step 1618;

[0144] Step 1616: tilt_stepa0 = tilt_stepa0 ÷ 2;

[0145] Step 1618: dTilta 0 = dTilta;

[0146] Step 1620: The first displacement table uses tilt_stepb0 in the last step;

[0147] Step 1622: Compare |Yright - Yleft| and |Yright_init - Yleft_init|;

[0148] Step 1624: dTiltb = tilt_stepb0;

[0149] Step 1626: dTiltb = 0;

[0150] Step 1628: dTiltb = -tilt_stepb0;

[0151] Step 1630: dTiltb = 0? If yes, go to Step 1638, else go to Step 1632;

[0152] Step 1632: dTiltb 0 x dTiltb < 0? If yes, go to Step 1634, else go to Step 1636;

[0153] Step 1634: tilt_stepb0 = tilt_stepb0 ÷ 2;

[0154] Step 1636: dTiltb0 = dTiltb;

[0155] Step 1638: if dTilta = 0 & dTiltb = 0;

[0156] Step 1640: break sub-loop 2.

[0157] At the same time, there is a sub-loop 2 which is almost the same as sub-loop 1, used to adjust the center of gravity of MTFmap graph, involving the process of angle adjustment, the only difference between sub-loop 2 and sub-loop 1 is that sub-loop 2 uses the step of last step as the initial step of angle adjustment of image sensor, tilt_stepa0 and tilt_stepb0.

[0158] That is, each step of the step-by-step rotation is to gradually adjust the angle between the image sensor and the lens.

[0159] Figure 17 is a flow chart of sub-loop 3 in the alignment method according to the embodiment of the present application, as shown in the figure, the flow of sub-loop 3 in the alignment method provided by an embodiment of the present application is as follows: Figure 17

[0160] Step 1702: the first displacement table is initially moved, dShiftX0 = xShift_step0 > 0, xShift_step0 = 0.02mm;

[0161] Step 1704: compare |ΔX| and |ΔX_init|;

[0162] Step 1706: dShiftX = xShift_step0;

[0163] Step 1708: dShiftX = 0;

[0164] Step 1710: dShiftX = -xShift_step0;

[0165] Step 1712: whether dShiftX = 0; if yes, execute step 1738, if no, execute step 1714;

[0166] Step 1714: whether dShiftX0 x dShiftX < 0; if yes, execute step 1716, if no, execute step 1718;

[0167] Step 1716: xShift_step0 = xShift_step0 ÷ 2;

[0168] Step 1718: dShiftX0 = dShiftX; ​

[0169] Step 1720: The first displacement table initially moves one step, dShiftY0 = yShift_step0 > 0, yShift_step0 = 0.02mm;

[0170] Step 1722: Compare |ΔY| and |ΔY_init|;

[0171] Step 1724: dShiftY = yShift_step0;

[0172] Step 1726: dShiftY = 0;

[0173] Step 1728: dShiftY = -yShift_step0;

[0174] Step 1730: dShiftY = 0? Step 1738, otherwise Step 1732;

[0175] Step 1732: dShiftY0 x dShiftY < 0? Step 1734, otherwise Step 1736;

[0176] Step 1734: yShift_step0 = yShift_step0 ÷ 2;

[0177] Step 1736: dShiftY0 = dShiftY;

[0178] Step 1738: dShiftX = 0 & dShiftY = 0?

[0179] Step 1740: Exit sub-loop 3.

[0180] ΔX is defined as the coordinate difference of the center of gravity of the MTF map to the coordinate origin on the X axis during adjustment, ΔX_init represents the coordinate difference of the center of gravity of the MTF map to the coordinate origin on the X axis in the state of image sensor and lens alignment, dShiftX is the step length of the displacement table component on the X axis this time, dShiftX0 is the step length of the displacement table component on the X axis last time, xShift_step0 is the step value, which can be set as xShift_step0 = 0.02mm. In the initial case, the influence of the movement of the image sensor along the X axis may not be clear, so the first displacement table can be initially moved one step, and the relative size of the absolute value |ΔX| and the absolute value |ΔX_init| is compared to determine.

[0181] ΔY is defined as the coordinate difference of the center of gravity of the MTF map to the coordinate origin on the Y-axis during the adjustment process, ΔY_init represents the coordinate difference of the center of gravity of the entire map to the coordinate origin on the Y-axis in the state of image sensor and lens alignment, dShiftY is the current step length of the displacement table assembly on the Y-axis, dShiftY0 is the last step length of the displacement table assembly on the Y-axis, yShift_step0 is the step length value, which can be set as yShift_step0=0.02mm. In the initial case, it may not be clear that the change of the image sensor moving along the Y-axis brings the influence, and the first displacement table can be initially rotated one step to view the relative size of the absolute value |ΔY| and the absolute value |ΔY_init| to determine.

[0182] According to some embodiments of the present application, the MTFmap map is generated according to the imaging of the image sensor, comprising: determining a sector area of each through-hole image in the imaging of the image sensor; generating the MTFmap map according to the arc edge of each sector area; wherein the concave side of the arc edge of each sector area faces the center of the imaging of the image sensor.

[0183] Specifically, the MTFmap map is generated according to the imaging of the image sensor, comprising: determining a sector area of each through-hole image in the imaging of the image sensor according to the setting, wherein the concave side of the arc edge of each sector area faces the center of the imaging of the image sensor, and then when the angle of the image sensor and the lens is aligned, the imaging of the image sensor forms a regular pattern, that is, each sector area surrounds a center of gravity, similar to a circular pattern formed by a plurality of sector areas. In this way, it can be more clearly known whether the angle of the image sensor and the lens is aligned, and the reliability is high.

[0184] Wherein, the sector area of each through-hole image in the imaging of the image sensor is determined, comprising: determining the imaging sector area of the through-hole according to the center of the imaging of the through-hole, the center of the imaging of the image sensor and the angle range.

[0185] Specifically, as shown in Figure 3 and Figure 12 Before determining the MTFmap map, the required image is determined first, the angle w of the connecting line between the center of each through-hole and the imaging center and the X-axis is calculated, in other words, the orientation angle of each through-hole meridian MTF or sagittal MTF.

[0186] As shown in Figure 12 After determining the angle w, a certain angle range wb is selected to obtain the sector area. When the sector area is selected, it is based on the angle w=arctan(x÷y) calculated for each through-hole, and the radius wherein x represents the coordinate of the X-axis of the center of the circle of the through hole, y represents the coordinate of the Y-axis of the circle of the through hole, the angular span of the entire sector region is w' ∈ [w-wb, w+wb], and wb can be equal to a set value between 10 degrees and 15 degrees.

[0187] As shown in FIG. 6, after obtaining the imaging of the image sensor, a region of interest (ROI) selection is first performed, the imaging of a through hole is selected, then a sector region of the imaging of the through hole is selected, then edge detection is performed on the sector region, after the edge is determined, extraction of effective pixels is performed, after the effective pixels of all the imaging of the through holes are extracted, a spread function is calculated, then the MTF is calculated, and then the determination of the MTFmap graph is performed. Figure 13 According to some embodiments of the present application, before the MTFmap graph is generated according to the imaging of the image sensor, the alignment method further comprises: controlling the first displacement table to move along a third direction, the third direction being perpendicular to both the first direction and the second direction; generating a curve of the change of MTF with position according to the imaging of the image sensor; and determining the focusing position of the image sensor and the lens according to the curve of the change of MTF with position.

[0188] Specifically, before the MTFmap graph is generated according to the imaging of the image sensor, the alignment method further comprises: preliminary focusing, that is, first controlling the first displacement table to move along a third direction, the third direction being perpendicular to both the first direction and the second direction, then generating a curve of the change of MTF with position according to the imaging of the image sensor, and determining the focusing position of the image sensor and the lens according to the curve of the change of MTF with position, thereby quickly focusing in a simple manner and improving the alignment efficiency of the image sensor and the lens.

[0189] Before the alignment operation of the image sensor and the lens is performed, the relative positions of the lens and the image sensor are first focused. The camera module is scanned along the Z-axis to form different fields of view corresponding to different positions of the through hole, a few through holes selected at equal intervals from the center to the edge are sufficient, and the middle can be skipped, a curve of the change of MTF with focusing position is determined, and finally the position of the image sensor is placed at the position corresponding to the maximum value of all the MTF curves.

[0190] As shown in FIG. 7, Field 1, Field 2, Field 3 and Field 4 respectively represent the fields of view from the center to the edge, which are obtained by scanning along the Z-axis. The dashed line in the figure represents a possible initial position of the image sensor, and the solid line represents a possible final position of the image sensor after rough focusing. Figure 18

[0191] ​The application adopts a circular pattern chart, and can accurately obtain the sagittal and meridian MTF of the position of the circular pattern on the whole image surface at one time; does not need to scan the change curve of MTF with focusing distance for multiple times; the whole MTF map is relatively rotationally symmetrical about the optical axis; the rotating direction can be accurately adjusted through the MTF map; the positions of the X axis and the Y axis can be accurately adjusted through the MTF map.

[0192] As shown in Figure 19 , an initial MTF map of a camera lens module with a and b direction angle offset, X and Y direction translation offset, and the selected test spatial frequency is 80 lp / mm, as shown in Figure 20 , the MTF map after the first round of adjustment of the a and b direction angle offset, as shown in Figure 21 , the MTF map of the camera lens module after the adjustment of the a and b direction angle offset, and the X axis direction and Y axis direction translation offset. The alignment device and the alignment method provided by the application can be used for the alignment of a single lens, and can also be used for the alignment of a more complex multi-group lens.

[0193] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0194] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. An alignment device, characterized in that, include: light source; A diagram, located on one side of the light source, is provided with an array of through holes; The displacement stage assembly includes: The first displacement stage is located on the side of the image card away from the light source. The first displacement stage is used to support the image sensor and adjust the position of the image sensor according to the MTF map of the image sensor. The second displacement stage is located on the side of the chart away from the light source. The first displacement stage is disposed on the second displacement stage. The second displacement stage is used to support the lens and adjust the position of the lens.

2. The alignment device according to claim 1, characterized in that, Each through-hole in the through-hole array is circular and has the same diameter. When aligning the image sensor and the lens, a fan-shaped area of ​​the image formed by the through-hole is captured, and this fan-shaped area is used to generate the MTF map.

3. The alignment device according to claim 2, characterized in that, The diameter of the through holes in the through hole array is greater than or equal to one-third of the center spacing of adjacent through holes in the same row or column, and less than or equal to one-half the center spacing of adjacent through holes in the same row or column.

4. The alignment device according to any one of claims 1 to 3, characterized in that, The center of the drawing card is provided with one of the through holes in the through hole array, and the through hole array is arranged axially symmetrically with respect to a straight line passing through the center of the drawing card.

5. The alignment device according to claim 4, characterized in that, The number of rows in the through-hole array is 2N+1; The number of columns in the through-hole array is 2N+1; Where N is a positive integer, and N is greater than or equal to 4.

6. An alignment method, characterized in that, The alignment method is performed by the alignment device according to any one of claims 1 to 5, wherein the first displacement stage of the alignment device carries an image sensor, and the second displacement stage of the alignment device carries a lens, and the alignment method comprises: Control the light source of the alignment device to emit light; Based on the imaging from the image sensor, an MTF map is generated; Based on the MTFmap, determine the MTF(Xcut) curve passing through the center of the MTFmap and along the tangent in the first direction, and the MTF(Ycut) curve passing through the center of the MTFmap and along the tangent in the second direction, wherein the first direction and the second direction are perpendicular. The displacement stage assembly is controlled to move until the MTF (Xcut) curve meets the first condition, the MTF (Ycut) curve meets the second condition, and the centroid of the MTF map coincides with the center of the image formed by the image sensor. Wherein, the first condition is that the absolute value of the first difference in the MTF(Xcut) curve belongs to the first interval, the absolute value of the first difference is the difference between the first length and the second length, the first length is the distance between the first point and the first midline in the MTF(Xcut) curve, the second length is the distance between the second point and the first midline in the MTF(Xcut) curve, and the first point and the second point are two points of equal height in the MTF(Xcut) curve; The second condition is that the absolute value of the second difference in the MTF(Ycut) curve belongs to the second interval, the absolute value of the second difference is the difference between the third length and the fourth length, the third length is the distance between the third point in the MTF(Ycut) curve and the second midline, the fourth length is the distance between the fourth point in the MTF(Ycut) curve and the second midline, and the third point and the fourth point are two points of equal height in the MTF(Ycut) curve.

7. The alignment method according to claim 6, characterized in that, Controlling the movement of the displacement stage assembly until the MTF (Xcut) curve meets a first condition, the MTF (Ycut) curve meets a second condition, and the centroid of the MTF map coincides with the center of the image captured by the image sensor, including: The displacement stage assembly is controlled to rotate until the MTF (Xcut) curve meets the first condition and the MTF (Ycut) curve meets the second condition. Control the movement of the displacement stage assembly until the centroid of the MTF map coincides with the center of the image captured by the image sensor; During the movement of the displacement stage assembly, if the MTF(Xcut) curve no longer satisfies the first condition or the MTF(Ycut) curve no longer satisfies the second condition, the displacement stage assembly is controlled to rotate until the MTF(Xcut) curve satisfies the first condition and the MTF(Ycut) curve satisfies the second condition.

8. The alignment method according to claim 7, characterized in that, Control the rotation of the displacement stage assembly until the MTF (Xcut) curve meets a first condition and the MTF (Ycut) curve meets a second condition, including: Control the displacement stage assembly to rotate one step around the first direction; If the absolute value of the first difference in the MTF (Xcut) curve belongs to the first interval, the step size for the next rotation around the first direction is determined to be 0. If the absolute value of the first difference in the MTF (Xcut) curve is less than the lower limit of the first interval, the step size for the next rotation around the first direction is determined as the first step size. If the absolute value of the first difference in the MTF (Xcut) curve is greater than the upper limit of the first interval, the next step size for rotation around the first direction is determined to be the negative first step size. Control the rotation of the displacement stage assembly until the MTF (Xcut) curve meets a first condition and the MTF (Ycut) curve meets a second condition, including: Control the displacement stage assembly to rotate one step around the second direction; If the absolute value of the second difference in the MTF (Xcut) curve belongs to the second interval, the step size for the next rotation around the second direction is determined to be 0. If the absolute value of the second difference in the MTF (Xcut) curve is less than the lower limit of the second interval, the next step size for rotation around the second direction is determined as the second step size. If the absolute value of the second difference in the MTF(Xcut) curve is greater than the upper limit of the second interval, the next step size for rotation around the second direction is determined to be a negative second step size.

9. The alignment method according to any one of claims 6 to 8, characterized in that, Based on the imaging from the image sensor, an MTF map is generated, including: Determine the fan-shaped region of each aperture image in the imaging of the image sensor; The MTF map is generated based on the arc edge of each of the said sector regions; In each of the fan-shaped regions, the concave side of the arc edge faces the center of the image sensor's imaging.

10. The alignment method according to any one of claims 6 to 8, characterized in that, Before generating an MTF map based on the image from the image sensor, the alignment method further includes: The displacement stage assembly is controlled to move along a third direction, which is perpendicular to both the first direction and the second direction. Based on the imaging from the image sensor, a curve showing the change of MTF with position is generated; The focus positions of the image sensor and the lens are determined based on the curve of MTF changing with position.

Images