Method and device for setting sub-micron level linear light spot encoder

Abstract

The invention discloses a method and a device for setting a submicron-grade linear light spot encoder, which are characterized in that a light spot measuring head is combined with a plurality of short-distance altimeters to detect a straight line error and an angle error so as to timely correct the straight line error and the angle error; the light spot leveling ruler is used for measuring the length of the interferometer and the reflector through the laser, and is matched with the position recording of the light spot to obtain extremely accurate position positioning, so that the device and the method for setting the sub-micron grade linear light spot encoder are formed; in addition, a grating is not needed, subsequent compensation processing in the prior art is omitted, the device is particularly suitable for occasions of extremely precise measurement and positioning, processing time can be shortened, and cost can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to a method and device for setting a sub-micron level linear spot encoder, and more particularly to a spot encoder system capable of measuring linear axis errors, especially the linear movement errors and rotation errors of the X-axis, Y-axis, and Z-axis in 3D space, which can all be measured to the sub-micron level by the linear spot encoder. Background Art

[0002] At present, magnetic scales and grating optical scales are used for mechanical positioning. For example, linear grating optical scales can only measure linear position errors. Other horizontal straightness errors, verticality errors, pitch errors (Pitch Error), yaw errors (Yaw Error), roll errors (Roll Error), etc. cannot be measured. Only after the grating optical scale is installed on the machine, other measuring instruments can be used for testing and calibration compensation to complete the production of the processing machine. This is the main reason why the overall accuracy of three-axis, five-axis, and multi-axis processing machines is limited during operation.

[0003] The application of laser spot in measurement began in 2003 when the US patent US 6642506B1 disclosed the technology of using this spot. The more famous one was the publication of Chinese patent CN 101751148B in 2008. Both mentioned the method of using the spot image as the measurement method of the one-dimensional displacement of the object. However, there are many problems in actual application. The main problem is that it is very problematic to obtain precise measurement data on the "plane" of the spot ruler using laser, because the spot ruler is set on a mobile platform, and the mobile platform is driven by the transmission mechanism. Therefore, when the mobile platform moves, it has its own up and down vibration, or the deflection error of the platform. These errors will be reflected on the spot ruler located next to the mobile platform. Therefore, the data measured on the spot ruler is not absolutely accurate. In addition, the calibration of the measuring machine itself is calibrated on the upper surface of the mobile platform, and the The spot ruler set beside the mobile platform has a position error in the spot ruler when measuring the spot. In addition, there are comprehensive errors of up and down vibration or rotation movement when moving. Under the requirement of precision measurement, these are considered to be errors of a very large range. Therefore, the existing technology is to make accurate measurements at a position without a reference. With the vibration and rotation errors in the three axes, even if a measurement value is obtained, it is not very accurate at all, and a lot of resource costs and time are wasted. Because of this, after the existing spot measurement distance, since the rotation errors in the three axes are not considered, subsequent compensation and correction work must be carried out afterwards, which increases a lot of subsequent costs and wastes time, which is the main problem of the existing spot measurement. Summary of the invention

[0004] The main purpose of the present invention is to provide a method and device for setting a sub-micron level linear spot encoder, which is to use a spot probe combined with a plurality of short-distance altimeters, and then combined with a high-precision spot ruler that has been precisely optically positioned, to form the device and method for setting a sub-micron level linear spot encoder of the present invention; since the processing machine is generally processed by a motor driving a screw or a linear motor driving a processing tool, the movement of such a driving mechanism will inevitably produce various three-axis runout or rotation errors. At this time, when the spot ruler is positioned, if it can directly measure all the accompanying errors when measuring the linear position, it can achieve complete and accurate The invention uses a laser to hit the microscopic rough surface of a spot ruler (or a plane object) to cause interference and diffraction to generate a spot, and the spot at this fixed point represents the only mark of the microscopic rough surface here. A series of spots on this plane can be used for precise measurement of optical positioning, and several short-range altimeters can measure the errors generated during movement and correct them. The spot ruler that has been precisely positioned can provide accurate measurement of displacement, so that a very precise linear spot encoder can be formed, which is particularly suitable for use in extremely precise measurement and positioning occasions, such as semiconductor equipment, high-precision processing equipment, high-precision measuring tools and other technical projects.

[0005] The present invention provides a method for setting a sub-micron level linear spot encoder, which at least comprises the following steps:

[0006] Step 1: Set a rough surface as a spot ruler; the rough surface can be used for laser irradiation to obtain a spot image;

[0007] Step 2: A spot measuring head is set up, in which a laser light source is set up, and a light is emitted at an oblique angle to the spot ruler to form a spot, and the light forming the spot is reflected to another angle, and a lens and an image sensor group are set up at the angle, and the reflected light is received by the lens and the image sensor group, and then transmitted to a computer with an image analysis function for subsequent processing;

[0008] Step 3: A short-distance altimeter is respectively arranged at the four corners of the spot measuring head, and the four short-distance altimeters are of the same type, and can respectively measure the distance between the end of the short-distance altimeter and the spot ruler, and the ends of the four short-distance altimeters form a square when viewed from above, and the spot formed by the light emitted by the spot measuring head hitting the spot ruler is exactly located in the center of the square formed by the ends of the four short-distance altimeters;

[0009] The four short-distance altimeters emit light from their ends to the light spot ruler, and then receive it, and measure the distances between the ends of the four short-distance altimeters and the light spot ruler respectively, and analyze the data of the four point distances and the light spot to see whether they are the same, and find out whether the path formed by the light spot is a straight line and horizontal movement;

[0010] Step 4: Position the linear length of the spot ruler described in step 2: a laser length measuring interferometer is provided, and a reflector is provided opposite to the linear direction thereof, and the bottom of the reflector is connected to a moving platform, on which the aforementioned spot ruler is placed; and the aforementioned spot measuring head is provided above one end of the spot ruler, and the spot measuring head and the spot ruler do not move at the same time; when the laser length measuring interferometer emits a laser beam from the transmitting end to the reflector, and receives the beam after reflection, the moving platform carries the laser beam to the reflector. When the spot ruler moves toward the laser length measuring interferometer, the reflector and the moving platform carrying the spot ruler are projected by the spot measuring head to obtain the spot, and the spot measuring head is fixed in the original position to emit light to the spot ruler to form a spot and record it. The spot on the spot ruler is then recorded, and the laser length measuring interferometer is used to locate the spot position. Even after the laser length measuring interferometer is removed, the address of the spot measuring head can still be determined completely by the memory spot pattern; in this way, the position of each spot relative to the spot ruler is obtained;

[0011] Step 5: The moving direction of the spot ruler in the X-axis must be connected to the laser light source, lens and image sensor group in the spot probe in the Z-axis, and the two must be set vertically;

[0012] According to the above method, a linear light spot encoder is constructed.

[0013] The present invention also provides a sub-micron-level linear spot encoder device, which at least includes: a spot ruler with a rough surface, which can be used for laser irradiation to obtain a spot; a spot measuring head, which is arranged above the spot ruler, and a laser light source is arranged inside, which emits light at an oblique angle to form a spot on the spot ruler, and makes the light forming the spot be reflected to another angle, and a lens and an image sensor group are arranged at the angle, and the reflected light is received by the lens and the image sensor group, and is connected to a computer with image analysis function The four short-distance altimeters are fixed at the four corners of the spot measuring head respectively, and the short-distance altimeters can measure the distance between the ends and the spot ruler respectively, and the ends of the four short-distance altimeters form a square when viewed from above, and the light spot formed by the light emitted by the spot measuring head hitting the spot ruler is located at the center of the square formed by the ends of the four short-distance altimeters; the moving direction of the spot ruler is perpendicular to the connecting line between the laser light source, lens and image sensor group in the spot measuring head.

[0014] The present invention also provides a sub-micron-level linear spot encoder device, which at least includes: a spot ruler with a rough surface, which can be used for laser irradiation to obtain a spot; a spot probe, which is arranged above the spot ruler, and a laser light source is arranged inside, which emits light at an oblique angle to form a spot on the spot ruler, and the light forming the spot is reflected to another angle, and a lens and an image sensor group are arranged at the angle, and the reflected light is received by the lens and the image sensor group, and is connected to a computer with an image analysis function for subsequent Processing; two short-distance altimeters are respectively arranged at opposite corners on both sides of the spot measuring head, and the lines connecting the two points on the spot ruler where the end light rays of the two short-distance altimeters hit are exactly set at a 45-degree angle to the X-axis line in the moving direction of the mobile platform, and the light spot shot by the spot measuring head is located at the center of the distance between the end light rays of the two short-distance altimeters hitting the spot ruler, so as to measure the height and angle error of the spot ruler during its travel; the moving direction of the spot ruler is perpendicular to the line connecting the laser light source, lens and image sensor group in the spot measuring head. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The figure is a schematic diagram illustrating the steps of the method of the present invention.

[0016] Figure 2 The figure is a schematic diagram of a light spot measuring head and a short-range altimeter of the method of the present invention.

[0017] Figure 3A The schematic diagram of the light spot level positioning method of the present invention is shown in FIG. Figure 1 .

[0018] Figure 3B The schematic diagram of the light spot level positioning method of the present invention is shown in FIG. Figure 2 .

[0019] Figure 4A It is a schematic diagram of the main device of the present invention and the operation between the light spot and the short-range altimeter.

[0020] Figure 4B for Figure 4A Top view of the .

[0021] Figure 5A This is a schematic diagram of an embodiment of the present invention using a fiber optic short-distance altimeter. Figure 1 .

[0022] Figure 5B This is a schematic diagram of an embodiment of the present invention using a fiber optic short-distance altimeter. Figure 2 .

[0023] Figure 5C This is schematic diagram 3 of an embodiment of the present invention using an optical fiber short-distance altimeter.

[0024] Figure 6 This is a diagram illustrating the relationship between light intensity and distance of the fiber optic short-range altimeter used in the method of the present invention.

[0025] Figure 7 It is a schematic diagram of the light spot ruler, four short-range altimeters, and the movement and rotation relationship between the light spot and each axial direction of the present invention.

[0026] Figure 8 Description of the relationship between the error caused by movement and the actual position when using spot measurement Figure 1 .

[0027] Fig. 9 Description of the relationship between the error caused by movement and the actual position when using spot measurement Figure 2 .

[0028] Fig.10 It is a schematic diagram of the light spot ruler, two short-range altimeters, and the movement and rotation relationship between the light spot and each axial direction of the present invention.

[0029] Explanation of reference numerals: 1-step; 2-step; 3-step; 4-step; 5-step; 10-spot measuring head; 11-light source; 12-lens and image sensor group; 20-spot ruler; 21-upper surface; 30-laser length measuring interferometer; 31-transmitting end; 40-reflector; 41-moving platform; 50-spot image; 60-computer; 70-short-range altimeter; 71-light emitting unit; 72-first light receiving unit; 73-second light Receiving unit; 80-enclosed space; 90-square area; A-linear range; r-distance; L, L0, L1, L2, L3, L4-light; LR-curve; LW-travel route; t-distance; e, Exx, Ezx, Eyx, ECx, EBx, EAx-error; θ, θ1-angle; A0-starting position; A1-first displacement point; A2-second displacement point; An-nth displacement point; E1, E2,…En-distance. DETAILED DESCRIPTION

[0030] The method of setting a sub-micron level linear spot encoder of the present invention at least comprises the following steps, see Figure 1 As shown:

[0031] Step 1: Set a rough surface as the spot ruler 20; see Figure 1 and Figure 2 The spot ruler 20 of the present invention does not need to be marked with a grating as in the prior art, and only needs to be processed into a rough surface and be used for laser irradiation to obtain the spot 50.

[0032] Step 2: Set up a spot probe 10: Please refer to Figure 1 and Figure 2 A laser light source 11 is arranged in the spot measuring head 10, which emits light L at an oblique angle to form a spot 50 on the spot ruler 20, and makes the light L forming the spot be reflected to another angle, and a lens and image sensor group 12 are arranged at the angle. The reflected light is received by the lens and image sensor group 12, and then transmitted to a computer 60 with image analysis function for subsequent processing.

[0033] Step 3: See Figure 2 , Figure 4A , Figure 4B As shown, at the four corners of the spot measuring head 10, there is respectively provided a short-distance altimeter 70, and the four short-distance altimeters 70 are of the same type, and can respectively measure the distance t between the end 71 of the short-distance altimeter 70 and the spot ruler 20, and the ends 71 ​​of the four short-distance altimeters 70 form a square when viewed from above, and the light spot 50 formed by the light L emitted by the spot measuring head 10 hitting the spot ruler 20 can be located exactly in the center of the square formed by the ends 71 ​​of the four short-distance altimeters 70 (as shown in FIG. Figure 4B shown).

[0034] like Figure 4A , Figure 4B , Figure 5A As shown, the four short-distance altimeters 70 emit light sources L2 from the end 71 to the light spot ruler 20, and then receive the light. Based on this, the distances t between the ends of the four short-distance altimeters 70 and the light spot ruler 20 are measured respectively. The data of the four point distances t and the light spot 50 are analyzed to see whether they are the same, and whether the path formed by the light spot 50 is a straight line and horizontal motion.

[0035] The above four short-distance altimeters 70 can use existing parts. The present invention takes the optical fiber short-distance altimeter 70 as an embodiment. Figure 5A , Figure 5B , Figure 5C As shown, the optical fiber type short-distance altimeter 70 includes a central light emitting unit 71, and a plurality of first light receiving units 72 are arranged outside the light emitting unit 71; and a plurality of second light receiving units 73 are arranged outside the first light receiving unit 72; the light emitting unit 71 emits the light L2 onto the spot ruler 20, and then the reflected light L3 and L4 are respectively emitted into the first light receiving units 72 and the second light receiving units 73 for reception, and are introduced into the light intensity sensor 74 to measure the light intensity within the distance t between the short-distance altimeter 70 and the spot ruler 20, and the light intensity is measured by the computer 60 (such as Figure 2 By comparing the two planes (as shown in the figure), it can be known whether the plane has errors such as axial torsion or deflection.

[0036] like Figure 5AAs shown, when the optical fiber short-distance altimeter 70 is an embodiment, the relationship between the distance t between the short-distance altimeter 70 and the light spot ruler 20 and the light intensity measured by the light intensity sensor 74 is as follows: Figure 6 As shown, after presenting a linear range A, a curve change is formed. According to experimental data, the linear range A is approximately between 10 and 20 micrometers (μm), which is sufficient for current precision measurement. That is, the scope of use of the present invention is sufficient.

[0037] Step 4: Position the light spot ruler 20 described in step 2 for straight line length:

[0038] Please see Figure 1 , Figure 3A , Figure 3B As shown, a laser length measuring interferometer 30 is provided, and a reflector 40 is provided opposite to the straight line thereof, and the bottom of the reflector 40 is connected to a moving platform 41. One embodiment is to form an L-shaped structure with the reflector 40 and the moving platform 41, and the aforementioned spot ruler 20 is placed on the moving platform 41; and the aforementioned spot measuring head 10 is provided above one end of the spot ruler 20, and the spot measuring head 10 and the spot ruler 20 do not move at the same time; when the laser length measuring interferometer 30 emits a laser light L1 to the reflector 40 from the transmitting end 31, and receives the light L1 after reflection, so as to measure the distance between the two, at this time, when the moving platform 41 carries the spot ruler 20 and moves toward the direction of the laser length measuring interferometer 30, the reflector 40 and the moving platform 41 carrying the spot ruler 20 are projected by the spot measuring head 10 to obtain the light The spot 50 is formed by the light spot measuring head 10, and the light spot measuring head 10 is fixed at the original position to emit light L to the light spot ruler 20 to form the light spot 50 and record it. Then, the light spot 50 on the light spot ruler 20 is recorded, and the position of the light spot 50 is located by using the laser length measuring interferometer 30. Even after the laser length measuring interferometer 30 is removed, the address of the light spot measuring head 10 can still be determined completely by relying on the memory light spot 50 pattern. In this way, the position of each light spot 50 point relative to the light spot ruler 20 is obtained. Since the position is obtained by the micro-measurement distance of the laser length measuring interferometer 30 and the reflector 40, for example, the light spot pattern on the light spot ruler 20 is recorded every 1 micron (μm) to define the scale on the light spot ruler 20. Therefore, the positioning and marking on the light spot ruler 20 can be performed in this way, which will be more accurate and convenient than directly marking the grating on the light spot ruler 20 in the prior art.

[0039] The aforementioned laser length measuring interferometer 30 first sets the displacement accuracy and transmits the information to the spot measuring head 10 , so that the spot measuring head 10 intercepts the spot 50 on the spot ruler 20 to achieve the required positioning accuracy.

[0040] The present invention uses a laser length measuring interferometer 30 to actually measure a length of several meters, and the linear positioning resolution can reach less than 1 micron (μm); Figure 3A , Figure 3B As shown, if the starting position A0 of the spot measuring head 10 on the spot ruler 20 is the position where the first spot 50 is formed, when the moving platform 41 moves toward the laser length measuring interferometer 30, it is equivalent to that the spot 50 formed by the spot measuring head 10 on the spot ruler 20 moves from the starting position A0 to the outer end of the spot ruler 20 (i.e., the right side of the figure). When the laser length measuring interferometer 30 sets a moving distance E1, the corresponding spot image movement amount can be read out in the image sensor (not shown in the figure) inside the spot measuring head 10; therefore, it moves from the starting position A0 to the first displacement point A1, the second displacement point A2... to the nth displacement point An in sequence, and the corresponding distances are E1, E2,...En, where:

[0041] E2=2E1,E3=3E1,……

[0042] So En = nE1, if E1 = 1 micron (μm), n = 1,000,000, then En = 1 meter

[0043] The image of the light spot 50 from the starting position A0 to the n-th displacement point An and its corresponding distance En are recorded in the computer 60; when the light spot probe 10 and the light spot ruler 20 are installed on the moving slide of the machine, the image of the light spot 50 at any n-th displacement point An and its corresponding address value En can be read on the light spot ruler 20 according to the light spot probe 10; similarly, according to the above method, if E1=1 micron (μm) is taken, a light spot ruler with a resolution and accuracy of 1 (μm) can be obtained, and if E1=0.1 micron (μm) is taken, a light spot ruler with a resolution and accuracy of 0.1 (μm) can be obtained, which means that the finer the measurement, the finer the level of measurement.

[0044] The laser length measuring interferometer 30 and the spot measuring head 10 are both fixed, while the reflector 40, the moving platform 41, and the spot ruler 20 are linearly moved by a transmission mechanism (such as a servo motor, a screw or a linear motor). Therefore, the horizontal direction of the light L1 emitted by the laser length measuring interferometer 30 is best aligned parallel to the upper surface 21 of the spot ruler 20, so as to effectively reduce the Abbe error. The so-called Abbe error means that the axis of the measuring instrument and the axis of the workpiece to be measured must be on the same straight line, otherwise an error will occur.

[0045] The laser interferometer 30, the reflector 40, the spot measuring head 10, the moving platform 41 carrying the spot ruler 20, etc. are all set in a closed space 80 with constant temperature, humidity and pressure for measurement, so that extremely accurate data can be obtained.

[0046] Step 5: The moving direction of the spot ruler 20 (ie, the X-axis) must be perpendicular to the line between the laser light source 11, the lens and the image sensor group 12 in the spot measuring head 10 (ie, the Z-axis).

[0047] In summary, the order of step 1, step 2, step 3, step 4, and step 5 is actually interchangeable, there is no absolute causal relationship, and they can also be performed simultaneously without affecting the actual purpose.

[0048] Please see Figure 4A , Figure 4B , Figure 7 As shown, the present invention is provided with four short-range altimeters 70, and combined with related structural configurations, the linear spot ruler can achieve the function of eliminating linear errors and angular errors, which is explained as follows:

[0049] When the spot probe 10 moves in the positive and negative X-axis directions of the spot ruler 20, the laser emission and reception of the spot probe 10 are in the Z-axis direction. Figure 4B , Figure 7 As shown, the light spot 50 is located in the center of the four short-distance altimeters 70, and all are located on the light spot ruler 20. The light spot ruler 20 may have errors when moving along the X-axis, including:

[0050] 1. Linear error: position error Exx on the X-axis, horizontal straightness error Ezx on the Z-axis, and verticality error Eyx on the Y-axis.

[0051] 2. Angular error: pitch error ECx (i.e. Pitch error), yaw error EBx (i.e. Yaw error), and roll error EAx (i.e. Roll error).

[0052] like Figure 7 , the Y-axis exit point is set on the light spot 50, and the symbols a, b, c, and d are the positions of the light spots emitted from the ends of the four short-distance altimeters 70, respectively. At the moment when the light spot 50 moves, the four points a, b, c, and d respectively measure the data of the height changes Δya, Δyb, Δyc, and Δyd. The light spot 50 has a Z-direction displacement of ΔZn at the Xn point position here. The standard values ​​of the above parameters are based on various fine-tuning devices before the light spot ruler 20 leaves the factory, such as using a PZT fine-motion brake to maintain a fixed standard position between the light spot probe 10 and the light spot ruler 20. When the light spot ruler 20 is installed on the machine in the factory, there will be a movement variable of the light spot image in the Z axis (i.e., Ezx error) and Δy variables of other short-distance altimeters 70. Therefore, it can be measured that the horizontal straightness error Ezx is the movement variable of the light spot image in the Z axis.

[0053] The verticality error on the Y axis is obtained by averaging the ΔY variation of the four short-range altimeters 70, namely:

[0054] Eyx=(Δya+Δyd+Δyc+Δyd) / 4

[0055] Pitch error (ECx)n=(Δya-Δyb)n or (Δyd-Δyc)n, where n is the code for different light spot positions, and the same applies below.

[0056] Transverse error (EAx)n = (Δya-Δyd)n or (Δyb-Δyc)n

[0057] Please see Figure 4A and Figure 8 As shown, Figure 8 The inner Z axis is the theoretical position, while the Z' axis is the actual deviation position, so the reflected light of the laser beam L is also deviated; since the laser light source 11 in the spot probe 10 is incident on the spot ruler 20 at an oblique angle θ, if observed from the X-axis direction, assuming that the laser light source 11 in the spot probe 10 is incident on point n on the surface of the spot ruler 20, when the standard height is parallel to the height of Δyn, the error of the laser center point n at the y1 position will be:

[0058] e=Δyn x tanθ=(Eyx)nx tanθ=(Ezx)n, where n is the code for different light spot positions.

[0059] The position error (Ezx)n of the spot ruler 20 in the Z-axis direction can be immediately obtained and directly corrected.

[0060] The yaw error (EBx)n is the angle variable of the spot image rotating about the Y axis.

[0061] As described in the previous paragraph of the present invention, if the existing technical means are compared, since the existing technology cannot directly obtain the error and correct it like the present invention, it is necessary to use a laser interferometer to measure the size of the workpiece mounted on the processing machine after the grating scale is installed on the processing machine, and then compare it with the displayed size data of the grating scale of the processing machine. Once there is an error, it is corrected by compensation. Therefore, the final accuracy of the processing machine needs to be combined with the compensation program action before it is the final result. Since the error value of the prior art is fixed and cannot be corrected in real time, it is its shortcoming and also the bottleneck in this industry. The present invention can directly obtain the error in real time and correct it during processing, which is the main advantage of the present invention.

[0062] Please see Figure 4A and Fig. 9 As shown, Fig. 9The X axis shown in the figure is the theoretical position, while the X' axis is the actual deviation position, so the reflected light L' of the laser light L also rotates; if the spot ruler 20 on the measuring tool has both angle and height errors when being transmitted, it has the following Fig. 9 The error (Eyx)n on the Y axis and the error (Exx)n on the X axis after rotation are shown above, viewed from the z-axis direction, where:

[0063] Error (Eyx)n = (Δya + Δyd + Δyc + Δyd)n / 4, and angle θ1 can be measured from the height difference and distance length from point a to point b, or the height difference and distance length from point d to point c. The distance between these two points is set in advance as in step 3 of the method, then: (Exx)n = (Eyx) x tanθ1, which can be easily and immediately obtained;

[0064] But if (Eyx) = 0, then the error (Exx)n = 0

[0065] Therefore, the present invention can still measure and correct angular and axial deviations in real time, so the measurement is more accurate and does not require subsequent compensation work like the prior art. The time is shortened and the accuracy is improved, which also saves work costs and subsequent inspection costs. This is an advantage of the present invention.

[0066] The method of the present invention described above can be used to obtain the sub-micron level linear spot encoder device of the present invention. Figure 2 , Figure 3A , Figure 4A , Figure 4B As shown, it contains at least:

[0067] A spot ruler 20 with a rough surface; the spot ruler 20 is placed on a moving platform 41, and does not need to set a grating mark as in the prior art, but only needs to be processed to a rough surface and can be used for laser irradiation to obtain a spot 50.

[0068] A spot measuring head 10 is arranged above the spot ruler 20, and a laser light source 11 is arranged inside to emit light L at an oblique angle to form a spot 50 on the spot ruler 20, and the light L forming the spot is reflected to another angle, and a lens and image sensor group 12 are arranged at the angle. The reflected light is received by the lens and image sensor group 12, and connected to a computer 60 with image analysis function for subsequent processing.

[0069] Four short-distance altimeters 70 are fixedly mounted at four corners of the spot measuring head 10, and the short-distance altimeters 70 can measure the distance t from the end 71 thereof to the spot ruler 20, and the ends 71 ​​of the four short-distance altimeters 70 form a square in a top view, and the light spot 50 formed by the light L emitted by the spot measuring head 10 hitting the spot ruler 20 can be located exactly in the center of the square formed by the ends 71 ​​of the four short-distance altimeters 70 (e.g. Figure 4B shown).

[0070] like Figure 4A , Figure 4B , Figure 5A As shown, the four short-distance altimeters 70 emit light sources L2 from the end 71 to the light spot ruler 20, and then receive the light. Based on this, the distances t between the ends of the four short-distance altimeters 70 and the light spot ruler 20 are measured respectively. The data of the four point distances t and the light spot 50 are analyzed to see whether they are the same, and whether the path formed by the light spot 50 is a straight line and horizontal motion.

[0071] The above four short-distance altimeters 70 can use existing parts. The present invention takes the optical fiber short-distance altimeter 70 as an embodiment. Figure 5A , Figure 5B , Figure 5C As shown, the optical fiber type short-distance altimeter 70 includes a central light emitting unit 71, and a plurality of first light receiving units 72 are arranged outside the light emitting unit 71; and a plurality of second light receiving units 73 are arranged outside the first light receiving unit 72; the light emitting unit 71 emits the light L2 onto the spot ruler 20, and then the reflected light L3 and L4 are respectively emitted into the first light receiving units 72 and the second light receiving units 73 for reception, and are introduced into the light intensity sensor 74 to measure the light intensity within the distance t between the short-distance altimeter 70 and the spot ruler 20, and the light intensity is measured by the computer 60 (such as Figure 2 By comparing the two planes (as shown in the figure), it can be determined whether the plane has any axial torsion or deflection errors.

[0072] like Figure 5A As shown, when the optical fiber short-distance altimeter 70 is an embodiment, the relationship between the distance t between the short-distance altimeter 70 and the light spot ruler 20 and the light intensity measured by the light intensity sensor 74 is as follows: Figure 6 As shown, after presenting a linear range A, a curve change is formed. According to experimental data, the linear range A is approximately between 10 and 20 micrometers (μm), which is sufficient for current precision measurement. That is, the scope of use of the present invention is sufficient.

[0073] Please see Figure 4A and Figure 4BAs shown, the moving direction of the spot ruler 20 (ie, the X-axis) must be perpendicular to the line connecting the laser light source 11, the lens and the image sensor group 12 in the spot measuring head 10 (ie, the Z-axis).

[0074] Another embodiment of the sub-micron level linear spot encoder device of the present invention has a more simplified structure, such as Fig.10 As shown, as the aforementioned main structure, there is a spot ruler 20 with a rough surface; the spot ruler 20 is placed on a moving platform 41, and above the spot ruler 20, all the structures of the spot probe 10 as mentioned above are provided; however, this embodiment is provided with two short-distance altimeters 70, which are respectively arranged at the two opposite corners of the spot probe 10, and the lines connecting the two points on the spot ruler 20 where the end lights of the two short-distance altimeters 70 are respectively hit are arranged at an angle of 45 degrees to the X-axis line in the moving direction of the moving platform 41, and the spot 50 hit by the spot probe 10 is just located at the center of the position distance r where the end lights of the two short-distance altimeters 70 are hit on the spot ruler 20, so as to measure the height and angle errors of the spot ruler 20 during its travel, and the relative axial error can be measured and corrected in time.

[0075] The structure described above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, equivalent or easy changes made by a person skilled in the art without departing from the spirit and scope of the present invention, such as slightly adding irrelevant optical elements, or roughly changing the shape or size of the elements, or replacing the components with equivalent components, or using different materials, or applying them in different occasions (such as optics, engineering, electronics, machinery, semiconductor equipment), etc., but using the features of the spot linear encoder of the present invention, should all be included in the features of the present invention.

Claims

1. A method for setting a sub-micron level linear spot encoder, characterized in that: It includes at least the following steps: Step 1: Set a rough surface as a spot ruler; the rough surface can be used for laser irradiation to obtain a spot image; Step 2: A spot measuring head is set up, in which a laser light source is set up, and a light is emitted at an oblique angle to the spot ruler to form a spot, and the light forming the spot is reflected to another angle, and a lens and an image sensor group are set up at the angle, and the reflected light is received by the lens and the image sensor group, and then transmitted to a computer with an image analysis function for subsequent processing; Step 3: A short-distance altimeter is respectively arranged at the four corners of the spot measuring head, and the four short-distance altimeters are of the same type, and can respectively measure the distance between the end of the short-distance altimeter and the spot ruler, and the ends of the four short-distance altimeters form a square when viewed from above, and the spot formed by the light emitted by the spot measuring head hitting the spot ruler is exactly located in the center of the square formed by the ends of the four short-distance altimeters; The four short-distance altimeters emit light from their ends to the light spot ruler, and then receive it, and measure the distances between the ends of the four short-distance altimeters and the light spot ruler respectively, and analyze the data of the four point distances and the light spot to see whether they are the same, and find out whether the path formed by the light spot is a straight line and horizontal movement; Step 4: Position the linear length of the spot ruler described in step 2: a laser length measuring interferometer is provided, and a reflector is provided opposite to the linear direction thereof, and the bottom of the reflector is connected to a moving platform, on which the aforementioned spot ruler is placed; and the aforementioned spot measuring head is provided above one end of the spot ruler, and the spot measuring head and the spot ruler do not move at the same time; when the laser length measuring interferometer emits a laser beam from the transmitting end to the reflector, and receives the beam after reflection, the moving platform carries the laser beam to the reflector. When the spot ruler moves toward the laser length measuring interferometer, the reflector and the moving platform carrying the spot ruler are projected by the spot measuring head to obtain the spot, and the spot measuring head is fixed in the original position to emit light to the spot ruler to form a spot and record it. The spot on the spot ruler is then recorded, and the laser length measuring interferometer is used to locate the spot position. Even after the laser length measuring interferometer is removed, the address of the spot measuring head can still be determined completely by the memory spot pattern; in this way, the position of each spot relative to the spot ruler is obtained; Step 5: The moving direction of the spot ruler in the X-axis must be connected to the laser light source, lens and image sensor group in the spot probe in the Z-axis, and the two must be set vertically; According to the above method, a linear light spot encoder is constructed.

2. The method for setting a sub-micron level linear spot encoder according to claim 1, characterized in that: In step 4, the reflector and the moving platform form an L-shaped structure.

3. The method for setting a sub-micron level linear spot encoder according to claim 1, characterized in that: In step 4, the horizontal direction of the light emitted by the laser length measuring interferometer is aligned parallel to the upper surface of the light spot ruler.

4. The method for setting a sub-micron level linear spot encoder according to claim 1, characterized in that: In step 4, the laser length measuring interferometer, the reflector, the spot measuring head, and the moving platform carrying the spot ruler are all placed in a closed space with constant temperature, constant humidity, and constant pressure for measurement.

5. A sub-micron level linear spot encoder device, characterized in that: At least include: A light spot ruler with a rough surface, capable of being used for laser irradiation to obtain a light spot; A spot measuring head is arranged above the spot ruler, and a laser light source is arranged inside the spot measuring head, which emits light at an oblique angle to form a spot on the spot ruler, and the light forming the spot is reflected to another angle, and a lens and an image sensor group are arranged at the other angle, and the reflected light is received by the lens and the image sensor group, and connected to a computer with an image analysis function for subsequent processing; Four short-distance altimeters are fixedly arranged at four corners of the spot measuring head, and each of the short-distance altimeters can measure the distance between its end and the spot ruler, and the ends of the four short-distance altimeters form a square when viewed from above, and the light spot formed by the light emitted by the spot measuring head hitting the spot ruler is located exactly in the center of the square formed by the ends of the four short-distance altimeters; The moving direction of the spot ruler is perpendicular to the connecting line between the laser light source, lens and image sensor group in the spot measuring head.

6. The sub-micron level linear spot encoder device according to claim 5, characterized in that: The light spot ruler is placed on a moving platform.

7. A sub-micron level linear spot encoder device, characterized in that: At least include: A light spot ruler with a rough surface, capable of being used for laser irradiation to obtain a light spot; A spot measuring head is arranged above the spot ruler, and a laser light source is arranged inside the spot measuring head, which emits light at an oblique angle to form a spot on the spot ruler, and the light forming the spot is reflected to another angle, and a lens and an image sensor group are arranged at the other angle, and the reflected light is received by the lens and the image sensor group, and connected to a computer with an image analysis function for subsequent processing; Two short-distance altimeters are respectively arranged at opposite corners on both sides of the spot measuring head, and the lines connecting the two points on the spot ruler hit by the end light of the two short-distance altimeters are arranged at a 45-degree angle to the X-axis line in the moving direction of the mobile platform, and the spot of light hit by the spot measuring head is located at the center of the distance between the end light of the two short-distance altimeters and the spot ruler, so as to measure the height and angle error of the spot ruler during its travel; The moving direction of the spot ruler is perpendicular to the connecting line between the laser light source, lens and image sensor group in the spot measuring head.

8. The sub-micron level linear spot encoder device according to claim 7, characterized in that: The light spot ruler is placed on a moving platform.

Images