JP2005090963A - Calibration method and device for measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate calibration method and device for measuring device by adding an alignment mark and a reflecting surface on parallel plates having high transparency or by marking in the circumferential direction of a circular cylinder having high transparency. <P>SOLUTION: This calibration method for calibrating the measuring device of an optical element is described as follows: a calibration primary standard 29 having at least two or more planes is installed on an optional reference position; a linear drive stage 15 is installed so that a moving shaft of the linear drive stage 15 becomes parallel to a normal on the plane of the calibration primary standard 29; an optical detector 21 is installed on the linear drive stage 15; the characteristic image of a direct action 29 is detected; the linear drive stage 15 is positioned on the second position; the characteristic image of the calibration primary standard 29 is detected by the optical detector 21; a plurality of images of positioning and the calibration primary standard 29 are detected as the need arises; a plurality of characteristic image information of the calibration primary standard is analyzed by an analysis device; thereby determines a relative angle between the normal on the plane of the calibration primary standard and the moving shaft of the linear drive stage 15 or a mechanical error of the direct-acting stage is, to thereby calibrate the measuring device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a calibration method and a calibration device for a measuring device and an inspection device, and relates to a method for measuring a relative displacement of an identifier or an alignment mark such as a flat plate, a prism, an optical element having a lens surface and a prism surface, and a calibration method for an inspection device. The present invention relates to a calibration device.

2. Description of the Related Art Conventionally, it is known to use a misalignment measuring device, a detecting device, and a positioning device using the same in calibration of a microscope or the like (see, for example, Patent Document 1).
FIG. 18 is a schematic diagram for explaining a conventional calibration method in which a cross-shaped alignment mark is attached to a chart made of a flat plate. FIG. 19 is a schematic diagram for explaining a conventional calibration method in which two parallel flat plates are positioned so that the parallel alignment marks overlap each other.
In FIG. 18, a cross-shaped alignment mark is attached to a chart 22 made of a flat plate. For this alignment mark, for example, a cross chart observation image is acquired by a detection system 21 equipped with a CCD.
In this way, the measurement apparatus is calibrated by observing with reference to some original device, in this case the chart 22, and grasping the relative positional relationship. Next, a description will be given of the calibration of the misalignment measuring apparatus that measures a workpiece having a thickness.
On the left side of FIG. 19, an alignment mark-containing flat plate 24 made of a transparent parallel plate and an alignment mark-containing flat plate 25 are arranged below the flat plate. The two parallel flat plates 24 and 25 are positioned so that the parallel and cross alignment marks overlap.
If the depth of focus of the detection system is so deep that the upper and lower alignment marks can be observed simultaneously, it can be observed as is, but if the depth of focus is shallow, the detection system is moved in the vertical direction to focus on each alignment mark.
At this time, when the cross alignment marks appear to overlap with each other when viewed from the detection system 21, it can be seen that the observation axis of the detection system and the plane of the parallel plate are orthogonal. Originally, the two crosshairs should overlap.
However, if the positions of the parallel flat plates 24 and 25 are shifted, they do not overlap like the two flat plate chart observation image 27. Even if the measuring device is calibrated in such a state, it is not correctly calibrated, so that the alignment of the two plates is very important.
Actually, since it is difficult to set the positional relationship between the two parallel flat plates correctly, the thick plate 26 with alignment marks marked on the upper and lower sides of the transparent parallel thick plate as shown on the right side of FIG. Sometimes used as a container. Thus, if marking is performed on one thick plate, handling during observation is easy.
However, it is difficult to make the horizontal position of the upper and lower cross alignment marks of the thick plate 26 coincide with each other with high accuracy, and the alignment mark may be shifted like the chart observation image 28 of the thick plate 26. Although the thick plate method is easy to handle during calibration, it is likely to be expensive and the accuracy is difficult to expect due to the need to create the original device with high accuracy.
In other words, it is only necessary to know the absolute value even if there is a positional deviation. That is, if the positional deviation amount of the upper and lower markings is found by another measurement method, it can be entered as a correction value in the calibration data.
However, in order to accurately measure the amount of misalignment, a high-accuracy measuring instrument is necessary, and the higher the accuracy, the more difficult it is to manufacture the upper and lower alignment marks without misalignment. .

According to Patent Document 1, it is disclosed that a plurality of infrared imaging devices image each workpiece coaxially from one direction via a common optical axis orthogonal to the XY plane. At this time, since an infrared imaging device is used as the imaging device of the imaging optical system, even if the workpiece is opaque and does not transmit visible light, if the workpiece is formed of a material that transmits infrared light, the red The alignment mark can be imaged through the work through external light.
Therefore, it is not necessary to move the imaging optical system back and forth between the workpieces. When the workpieces are aligned, the clearance can be set very small, and the moving distance when the workpieces are overlapped is shortened.
In addition, since the focus area of each infrared imaging device is set at a position where each alignment mark can be selectively imaged, two alignment marks are not simultaneously imaged by one infrared imaging device.
Therefore, when the coordinates of the alignment mark are calculated based on the output signal of each imaging device, only one alignment mark is captured on each screen, so that the center coordinates of each alignment mark can be easily determined based on the image signal. Can be sought.
This misalignment measurement apparatus has a similar measurement target, but the calibration method of the measurement apparatus is not specified. For this reason, it is considered that an alignment mark provided on the top and bottom of the flat chart plate described in the above-described prior art is used as a master.
JP 2000-276233 A

However, the conventional master has a technique in which alignment marks are provided on both sides of a parallel plate so that they are coaxial with each other. This technique is simple and easy to understand, and is used as a prototype for positioning the microscope and stage.
However, with this method, when adding alignment marks to be attached to both sides of a parallel plate, for example, a circular alignment mark, it is necessary to match the center axes of both sides at the time of processing, that is, to align the axes of both sides. was there.
For this reason, a processing machine for processing alignment marks is also required to have a high-precision positioning technique, and it has been extremely difficult to manufacture a master having an accuracy of about sub-μm.
Even if a relative misalignment occurs between the double-sided alignment marks, it can be used as a master if the absolute value of the misalignment amount is known. However, in actuality, it is difficult to measure the positional deviation amount with high accuracy, and it is difficult to use it as a high-accuracy master.
In the conventional calibration prototype, it is difficult to place alignment marks with the axes aligned with high precision on both sides of the parallel plate, and the positioning accuracy of the processing machine is required, and the cost of the prototype is very high.
Therefore, in order to solve the above problems, the object of the present invention is to add an alignment mark and a reflecting surface to a highly transparent parallel plate, or to mark in the circumferential direction of a highly transparent cylinder. An object of the present invention is to provide an accurate measuring apparatus calibration method and calibration apparatus.

In order to solve the above problems, the invention described in claim 1 is a measuring device calibration method for calibrating a measuring device for an optical element, wherein a calibration master having at least two planes is provided at an arbitrary reference position. The linear movement stage is installed so that the axis of movement of the linear movement stage is parallel to the normal of the plane of the calibration master, and an optical detector is installed on the linear movement stage, A linear motion stage is positioned at a first position, a characteristic image of the calibration master is detected by the optical detector, the linear motion stage is positioned at a second position, and the calibration is performed by the optical detector. The calibration image is detected by detecting a feature image of the master, and if necessary, further detecting a plurality of positioning and calibration master images and analyzing the feature image information of the plurality of calibration masters with an analyzer. The normal of the original plane and the straight line Relative angle and the movement axis of the stage, and wherein the measuring device calibration method for calibrating the measuring device seeking mechanical error of the linear stage.
According to a second aspect of the present invention, there is provided a measurement apparatus calibration apparatus for calibrating an optical element measurement apparatus, comprising: an arbitrary reference position, a linear motion stage, a calibration master, an optical detector, and an analysis apparatus. It features a calibration device for a measuring device.
According to a third aspect of the present invention, in the calibration prototype, an alignment mark is formed on one surface, and a parallel plate having high transparency is in contact with a parallel plate having high reflectivity on the opposite surface. A measuring device calibration apparatus according to claim 2 is provided.
According to a fourth aspect of the present invention, the calibration prototype is processed such that an alignment mark is formed on one surface and a parallel plate having high transparency has a high reflectance on the opposite surface. A measuring apparatus calibration apparatus according to claim 2.
The invention according to claim 5 is characterized in that the alignment mark has a low reflectance, and the calibration device for a measuring apparatus according to claim 3 or 4 is characterized.

In the invention according to claim 6, the calibration prototype has a highly parallel flat plate, one of which is a flat surface on the one side and the other having a plurality of uneven planes parallel to the opposite surface. 5. The calibration device for a measuring apparatus according to claim 4, wherein an alignment mark is created and reflection processing is applied to a plurality of different flat portions.
In the invention according to claim 7, the calibration prototype has a parallel plate with high transparency, one of which is entirely flat and the other of which is a plurality of uneven planes parallel to the opposite surface. 5. The calibration device for a measuring apparatus according to claim 4, wherein an alignment mark is created in the portion, and a reflection processing is applied to the entire plane portion.
Further, in the invention according to claim 8, the calibration prototype has an alignment mark formed on one side of a parallel plate having a plurality of flat portions on both sides, and the other side is subjected to reflection processing. A measuring apparatus calibration apparatus according to claim 4.
Further, the invention according to claim 9 is characterized in that the calibration prototype is a combination of a plurality of plates having the same refractive index, one having a flat surface on the entire surface and the other having a plurality of uneven planes parallel to the opposite surface. 5. The calibration device for a measuring apparatus according to claim 4, wherein a high parallel plate is formed, an alignment mark is processed on the entire flat surface portion, and reflection processing is performed on a plurality of different flat surface portions.
Further, the invention according to claim 10 is a transparency in which the calibration prototype is combined with a plurality of plates having the same refractive index, one having a flat surface on the whole and the other having a plurality of uneven planes parallel to the opposite surface. The measuring device calibration apparatus according to claim 4, wherein a parallel plate having a high height is produced, alignment marks are processed in a plurality of uneven plane portions, and reflection processing is applied to the entire plane portion.
Further, the invention according to claim 11, the calibration prototype is a combination of a plurality of plates having the same refractive index, creating a parallel plate having a plurality of flat portions on both sides, and processing an alignment mark on one side, 5. The calibration device for a measuring apparatus according to claim 4, wherein the other surface is subjected to reflection processing.
The invention according to claim 12 is the calibration of the measuring apparatus according to claim 2, wherein the calibration prototype creates a plurality of alignment marks on a circumferential surface of a highly transparent cylinder in a direction perpendicular to the cylinder axis. Features the device.
Further, the invention according to claim 13 is the measuring apparatus according to claim 2, wherein the calibration prototype creates a circular alignment mark in a direction orthogonal to the cylinder axis on the circumferential surface of the highly transparent cylinder. Features a calibration device.

  Highly accurate master unit that can calibrate the positional relationship between an arbitrary reference position and the moving axis of the linear motion stage with high accuracy, reducing the influence of dust, and having a very high degree of coaxiality. Can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a misalignment measuring apparatus calibrated by a calibration method and a calibration apparatus according to the present invention. The operation of the misalignment measuring apparatus will be described with reference to FIG.
As an optical element position adjustment jig on an anti-vibration table (not shown), a link type alignment mechanism comprising an XY stage 1, a rotary stage 2, an elastic hinge 4, an actuator 3, and a spherical joint 5, an optical element installation top plate 6. There is a holder 7 for attaching an optical element.
The detection system includes an XY stage 16 in the detection unit base 8 and a Z-axis stage 15 for adjusting the focal position. The optical system 10 includes a microscope objective lens 9 having a long operation and a shallow depth of focus, a light source 11, a polarization unit 12, a CCD mounting unit 13, and a high-pixel CCD unit 14 as a photoelectric conversion unit.
First, the optical element of the object to be measured is set in the holder 7 and placed on the position adjusting jig. The optical element is, for example, a glass transparent flat plate with cross alignment marks on both flat surfaces.
Next, position adjustment is performed by the XY stage 1, the rotary stage 2, and the link type alignment mechanism so that the alignment mark of the optical element can be read with respect to the optical axis of the optical system.
Next, the Z-axis stage 15 is moved downward so that the alignment mark on the upper part of the transparent flat plate is in focus, and an image of the alignment mark on the upper part is acquired. Subsequently, the Z-axis stage 15 is moved further downward to be positioned at a position where the lower alignment mark on the transparent flat plate is in focus, and an image of the alignment mark at this time is acquired.
In this way, a plurality of pieces of image information are sequentially obtained, and image feature amounts are extracted and compared with an analysis device (not shown) such as a computer, thereby comparing relative positional deviation information, for example, upper alignment of a transparent flat plate. The amount of lateral displacement between the mark and the lower alignment mark can be detected.
At this time, if an original device having no misalignment amount between the upper and lower alignment marks written on the transparent flat plate is used, the normal line of the original device and the stage moving axis of the Z-axis stage 15 can be observed by observing the misalignment amount. Can determine the amount of inclination.

FIG. 2 is a schematic perspective view showing a configuration in which the first embodiment of the calibration prototype is installed on a flat reference surface in the optical element displacement measuring apparatus. FIG. 3 is a schematic perspective view for explaining an alignment mark different from FIG.
In the optical element misalignment measuring device, a calibration master is installed on the reference surface of the flat plate 33. As the calibration prototype, for example, a plurality of alignment marks 30 are provided in the circumferential direction of the rod lens 29 placed on the flat plate 33 and used. The two marks 30 are provided at opposing positions separated by 180 °, for example.
At this time, the stage movement direction of the linear motion stage is set to be parallel to the normal line of the reference plane, and an optical detector 21, for example, a CCD camera is installed on the linear motion stage, So that linear motion is possible.
The rod lens 29 has a plurality of alignment marks 30 in the circumferential direction. The rod lens 29 is rotated and fixed so that one of the alignment marks 30 is above the rod lens 29 and the other is below the rod lens 29.
First, in order to observe the alignment mark 30 above the rod lens 29, the linear motion stage is moved so that the focal position of the detector 21 is positioned at the upper alignment mark 30. The upper alignment mark 30 is detected by the detector 21, for example, acquired as image information by a CCD.
Next, in order to observe the alignment mark 30 below the rod lens 29, the linear motion stage is moved in a direction approaching the rod lens 29, and the detection system 21 is positioned so that the focal position becomes the alignment mark 30 below. . The upper alignment mark is detected by the detection system, for example, acquired as image information by a CCD.
At this time, since the lower alignment mark 30 is observed through the rod lens 29, the moving distance of the linear motion stage and the thickness of the rod lens 29 do not always match due to the lens effect.

Next, in order to determine whether or not the reference plane and the linear motion stage axis are orthogonal, the upper and lower images are analyzed, and if the two images overlap, it can be determined that they are orthogonal. Of course, a plurality of two or more images may be acquired and analyzed.
In the calibration prototype, it is desirable that the normal line of the reference plane and the line connecting the upper and lower alignment marks 30 are parallel to each other. As explained in the prior art, it is difficult to make the alignment mark 30 parallel to the top and bottom of the flat plate 33, but if it is cylindrical, it can be processed with a rotating system, for example, the alignment mark can be processed with a lathe. Therefore, it becomes possible to engrave the upper and lower marks accurately.
Further, by holding the rod lens 29 with the V block, it is easy to make the reference plane and the rotation center axis of the rod lens 29 parallel to each other, and it is possible to perform highly accurate positional deviation calibration by an inexpensive method. .
Further, if the alignment mark 30 of the rod lens 29 is formed into a linear groove 32 in the circumferential direction, it becomes easier. For example, if the rod lens 29 is attached to a rotary machine and marked with an inkjet head capable of printing magic or fine lines, a linear alignment mark perpendicular to the rotation axis can be attached in the circumferential direction.
When machining with a lathe, a rod lens is set on a machining jig, and a groove perpendicular to the rotation axis of the rod lens can be obtained by machining a groove with a cutting tool. With these linear alignment marks in the circumferential direction, the displacement measuring apparatus can be calibrated as before.

FIG. 4 is a schematic perspective view for explaining a second embodiment of a calibration prototype capable of performing high-precision calibration with an alignment mark on one side of a parallel plate. FIG. 5 is a front view showing the calibration prototype of FIG. FIG. 6 is a schematic diagram showing alignment marks observed with the calibration prototype of FIG.
Assume that there is an alignment mark, for example, a double circular alignment mark 36, on one side of the parallel plate 35 as shown in FIG. The parallel flat plate 35 is made of a transparent material such as glass or plastic, and the parallel flat plate 35 is placed on a high reflectivity flat plate 34 obtained by mirror processing.
With such a configuration, it is possible to observe the double circular alignment marks as if they were reflected by the mirror, as if the double circular alignment marks 36 and 36 ′ were on the front and back of the parallel plate 35, respectively. Calibration is performed using this characteristic.
First, a high reflectivity flat plate 34 and a parallel plate 35 are installed on the reference surface, a linear motion stage is installed so as to be able to move in parallel with the normal line of the reference surface, and a detector 21 fixed to the linear motion stage, for example, a CCD camera. Then, the linear motion stage is positioned so that the focal point is aligned with the position of the alignment mark 36. At this time, an image such as the alignment mark observation image 41 can be acquired.
Next, when the linear motion stage is moved closer to the parallel flat plate 35, the alignment mark 36 is reflected by the mirror surface, and the CCD camera is focused on a position where the reflected image can be observed. An image like 42 can be acquired.
Next, in order to determine whether or not the reference plane and the linear motion stage axis are orthogonal, the observation image 41 of the alignment mark 36 and the observation image 42 of the reflection image of the alignment mark 36 are analyzed and compared, for example, two images If the centers of the two coincide, it can be determined that they are orthogonal. Of course, images at arbitrary positions may be compared, and a plurality of analysis images, for example, three or four images may be acquired and analyzed.
If this method is used, calibration marks different in the depth direction having an extremely high degree of coaxiality can be obtained by simply attaching the alignment mark 36 to one side of the parallel plate 35.
In the method of marking on the top and bottom of the parallel plate as described in the prior art, it is difficult to make a high-accuracy master because it is necessary to align the upper and lower processing machine axes when processing the mark. However, by using this method, an inexpensive and highly accurate original device can be provided.

FIG. 7 is a schematic perspective view for explaining a third embodiment of a calibration prototype capable of performing high-precision calibration in which an alignment mark is attached to one side of a parallel plate obtained by simplifying the configuration shown in FIG. FIG. 8 is a front view showing the calibration prototype of FIG. FIG. 9 is a schematic diagram showing alignment marks observed with the calibration prototype of FIG.
Assume that there is an alignment mark, for example, a double circular alignment mark 36, on one side of the parallel flat plate 35 as shown in FIGS. The parallel plate 35 is made of a transparent material such as glass or plastic, and the back surface of the parallel plate 35 is made into a reflection processing surface 38 by mirror processing or the like.
In this way, the double alignment mark 36 is an image reflected by the mirror, and it can be observed as if the double circular alignment marks 36, 36 'exist on the front and back of the parallel plate.
Compared with the method using two parallel flat plates, there is less possibility of foreign matter entering between the plates and causing an angle error, and the cost can be reduced because there is only one parallel flat plate.
If this method is used, calibration marks different in the depth direction having an extremely high degree of coaxiality can be obtained simply by attaching an alignment mark to one side of a parallel plate. In the method of marking on the top and bottom of the parallel plate as described in the prior art, it is difficult to make a high-accuracy master because it is necessary to align the upper and lower processing machine axes when processing the mark. However, by using this method, an inexpensive and highly accurate original device can be provided.
The alignment mark 36 used in FIGS. 4 and 7 may be increased or decreased in reflectance. When observing the alignment mark 36, there is no problem whether the reflectance is high or low.
However, when observing the alignment mark reflection image, the contrast is deteriorated because it is buried in the reflected light of the mirror surface. Therefore, the alignment mark 36 can improve the contrast and the calibration accuracy when the reflectance is low.

FIG. 10 is a schematic perspective view for explaining a fourth embodiment of a calibration prototype capable of performing high-precision calibration showing a configuration in which an alignment mark, for example, a double circular alignment mark, is provided on a flat surface on one side of a parallel plate. is there. FIG. 11 is a front view showing the calibration prototype of FIG. FIG. 12 is a schematic diagram showing alignment marks observed with the calibration prototype of FIG.
As described above, if a mirror is used, a highly accurate original device can be provided at low cost from the alignment mark and the reflection image of the alignment mark. However, the position of the observation image is two points, the upper part and the lower part, and only a limited stroke of the linear motion stage can be verified. Therefore, it is necessary to prepare a prototype corresponding to the stroke, which takes time and cost.
Assume that there is an alignment mark, for example, a double circular alignment mark 36 (36a, 36b), on the flat portion of one side of the parallel plate 35 as shown in FIG. A stepped portion 43 is attached to the back surface of the parallel plate 35 so that the back surface is reflective. The parallel plate 35 and the stepped portion 43 are made of a transparent body such as glass or plastic.
The double alignment mark is an image reflected by the mirror, and it can be observed as if double circular alignment marks exist on the front and back of the parallel plate. At this time, the thickness of the plate differs depending on the step 43. Then, a difference appears in the position where the reflected image of the alignment mark can be seen.
First, when the alignment mark 36 is observed, an alignment mark observation image 49 is obtained. Next, when it is brought closer to a flat plate, the alignment mark reflection image at a thin plate thickness is focused, and the image of the alignment mark outer reflection image 50 can be observed. Further, if the plate is brought closer to the flat plate, the alignment mark reflection image at the thick plate is focused, and the image of the alignment mark inner reflection image 51 can be observed.
That is, by installing the stepped portion 43, the focus position can be set at three or more points, which conventionally had only two points, the upper part and the lower part, and the posture state during the stage movement can be detected. If the number of steps is increased, the behavior of the stage during movement can be observed in detail. As a result, calibration of the reference plane and the linear motion stage can be performed with higher accuracy.
Moreover, it is not necessary to process this step part directly into a parallel plate, and a plurality of members may be combined. For example, if two parallel plates having different sizes are prepared and the two plates are stacked and fixed, the same effect can be obtained and the cost can be reduced.

FIG. 13 is a schematic perspective view for explaining a fifth embodiment of a calibration prototype capable of performing high-precision calibration showing a configuration in which an alignment mark, for example, a double circular alignment mark, is provided on a flat surface on one side of a parallel plate. is there. FIG. 14 is a front view showing the calibration prototype of FIG. FIG. 15 is a schematic diagram showing alignment marks observed with the calibration prototype of FIG.
As described in the fourth embodiment, by adding the stepped portion, the plate thickness of the parallel plate can be changed, and the focal position of the reflected image of the alignment mark can be increased.
In the above-described configuration, the alignment mark is attached to the flat portion and the mirror is attached to the step portion. However, the focal position can be increased even in the reverse configuration.

As shown in FIG. 13 and FIG. 14, reflection processing is performed on a flat portion of one side of the parallel flat plate 35, and a stepped portion 52 is provided on the opposite surface of the parallel flat plate 35, so that an alignment mark, for example, a double circular alignment mark 36 (36 a 36b). The parallel plate 35 and the stepped portion 52 are made of a transparent body such as glass or plastic.
The double alignment mark is an image reflected by the mirror and can be observed as if double circular alignment marks exist on the front and back of the parallel plate. At this time, the thickness of the plate differs depending on the stepped portion 52. Then, a difference appears in the position where the reflected image of the alignment mark can be seen.
First, when the detector 21 is observing the alignment mark inner side 36b of the stepped portion 52, an alignment mark inner side observation image 54 is obtained. Next, when it is brought closer to a flat plate, a parallel flat plate alignment mark observation image 55 is obtained.
Furthermore, if the distance is closer to a flat plate, the alignment mark reflection image at a thin plate thickness is focused, and the alignment mark outer reflection image observation image 56 can be observed. Further, when the plate is brought closer to the flat plate, the alignment mark reflection image at the thick plate is focused, and the alignment mark inner reflection image observation image 57 can be observed.
In other words, by installing the stepped portion 52, it was possible to set the focal position to 4 points or more, which was conventionally only two points at the top and bottom, and to detect the posture state while moving the stage, making it easier to manufacture. is there. As a result, calibration of the reference plane and the linear motion stage can be performed with higher accuracy.
Moreover, it is not necessary to process this step part directly into a parallel plate, and a plurality of members may be combined. For example, if two parallel plates having different sizes are prepared and the two plates are stacked and fixed, the same effect can be obtained and the cost can be reduced.

FIG. 16 is a schematic front view for explaining a sixth embodiment of a calibration prototype capable of performing high-precision calibration showing a configuration in which an alignment mark, for example, a double circular alignment mark, is provided on a flat portion on one side of a parallel plate. is there. FIG. 17 is a schematic diagram showing alignment marks observed with the calibration prototype of FIG.
As described in the fourth and fifth embodiments, by adding the stepped portion, the plate thickness of the parallel plate can be changed, and the focal position of the reflected image of the alignment mark can be increased.
In the above-described configuration, one of the parallel plates is a flat surface and the other is a step surface. However, the focal position can be increased on both surfaces. As shown in FIG. 16, the alignment mark 36 (36a, 36b) is applied to the stepped portion 65 on one side of the parallel flat plate 35, and the reflection processing 63 is applied to the stepped portion 62 on the opposite surface.
Assume that the alignment marks include, for example, double circle alignment marks 36a and 36b. The parallel flat plate 35 and the step portions 65 and 62 are made of a transparent body such as glass or plastic.
The double alignment mark is an image reflected by the mirror, and it can be observed as if double circular alignment marks 36a, 36b, 36a ', 36b' exist on the front and back of the parallel plate. If the thickness of the flat plate differs depending on the position, a difference appears in the position where the reflected image of the alignment mark can be seen.
When the detector 21 is observing the alignment mark inner side 36b of the step portion 65, an alignment mark inner side observation image 66 is obtained. Next, if it approaches the flat plate, the alignment mark outer side observation image 67 of the parallel flat plate portion is obtained.
Further, if the image is brought closer to the flat plate, the alignment mark reflection image on the parallel flat plate portion is focused, and the alignment mark inner reflection image observation image 68 can be observed. Further, if the plate is brought closer to the flat plate, the alignment mark reflection image at the step is focused, and the alignment mark outer reflection image observation image 69 can be observed.
In other words, by installing a stepped part, it was possible to set the focal position to 4 points or more in the past, which had only two points at the upper and lower parts, detect the posture state while moving the stage, and manufacture is easier. is there. As a result, calibration of the reference plane and the linear motion stage can be performed with higher accuracy.
Moreover, it is not necessary to process this step part directly into a parallel plate, and a plurality of members may be combined. For example, if two parallel plates having different sizes are prepared and the two plates are stacked and fixed, the same effect can be obtained and the cost can be reduced.

It is the schematic which shows the position shift measuring apparatus calibrated with the calibration method and calibration apparatus by this invention. FIG. 3 is a schematic perspective view showing a configuration in which the first embodiment of the calibration prototype is installed on a flat reference surface in the optical element misalignment measuring apparatus. It is a schematic perspective view explaining the alignment mark different from FIG. It is a schematic perspective view explaining 2nd Embodiment of the calibration original equipment which can implement the highly accurate calibration which attached the alignment mark to the single side | surface of a parallel plate. It is a front view which shows the calibration original equipment of FIG. It is the schematic which shows the alignment mark observed with the calibration original equipment of FIG. FIG. 5 is a schematic perspective view for explaining a third embodiment of a calibration prototype capable of performing high-precision calibration in which an alignment mark is attached to one side of a parallel plate in which the configuration shown in FIG. 4 is simplified. It is a front view which shows the calibration original equipment of FIG. It is the schematic which shows the alignment mark observed with the calibration original equipment of FIG. It is a schematic perspective view explaining 4th Embodiment of the calibration original equipment which can implement the highly accurate calibration which shows the structure which has the alignment mark, for example, a double circle alignment mark, in the plane part of the single side | surface of a parallel plate. It is a front view which shows the calibration original equipment of FIG. It is the schematic which shows the alignment mark observed with the calibration original equipment of FIG. It is a schematic perspective view explaining 5th Embodiment of the calibration original equipment which can implement the highly accurate calibration which shows the structure which has the alignment mark, for example, a double circle alignment mark, in the plane part of the single side | surface of a parallel plate. FIG. 14 is a front view showing the calibration prototype of FIG. It is the schematic which shows the alignment mark observed with the calibration original equipment of FIG. It is a schematic front view explaining 6th Embodiment of the calibration original device which can implement the highly accurate calibration which shows the structure which has an alignment mark, for example, a double circular alignment mark, in the plane part of the single side | surface of a parallel plate. It is the schematic which shows the alignment mark observed with the calibration original equipment of FIG. It is the schematic explaining the conventional calibration method by which the cross-shaped alignment mark is attached to the chart made from the flat plate. It is the schematic explaining the conventional calibration method which is positioned so that two parallel flat plates may be parallel and the cross alignment mark may overlap.

Explanation of symbols

15 Linear motion stage (Z-axis stage)
21 Optical detector 29 Calibration prototype (rod lens)
36 Alignment Mark 35 Parallel Plate 41 Alignment Mark Observation Image 42 Alignment Mark Reflection Image Observation Image 43 Step

Claims (13)

In a measuring device calibration method for calibrating an optical element measuring device,
A calibration prototype having at least two planes is installed at an arbitrary reference position, and the linear motion stage is installed so that the movement axis of the linear motion stage is parallel to the normal of the calibration prototype plane. An optical detector is installed on the linear motion stage, the linear motion stage is positioned at a first position, a characteristic image of the calibration master is detected by the optical detector, and the linear motion stage is A characteristic image of the calibration prototype is detected by the optical detector after positioning at a second position, and if necessary, a plurality of positioning and calibration prototype images are further detected, and the plurality of calibration prototypes are detected. The measurement apparatus is configured to obtain a relative angle between a plane normal of the calibration prototype and a moving axis of the linear motion stage and a mechanical error of the linear motion stage by analyzing the characteristic image information of Measurement characterized by calibrating置校 positive way.   A calibration apparatus for a measurement apparatus that calibrates a measurement apparatus for an optical element, comprising: an arbitrary reference position; a linear motion stage; a calibration master; an optical detector; and an analysis apparatus. apparatus.   3. The calibration prototype is provided with an alignment mark formed on one surface, and a parallel plate having high transparency is placed so that its opposite surface is in contact with a parallel plate having high reflectivity. Calibration equipment for measuring devices.   3. The measurement according to claim 2, wherein the calibration original is processed so that an alignment mark is formed on one surface and a parallel plate having high transparency has a high reflectance on the opposite surface. Equipment calibration device.   5. The calibration apparatus for a measuring apparatus according to claim 3, wherein the alignment mark has a low reflectance.   The calibration prototype has a highly transparent parallel plate, one of which is entirely flat and the other is a plurality of steps that are parallel to the opposite surface. 5. The calibration apparatus for a measuring apparatus according to claim 4, wherein the flat surface portion is subjected to reflection processing.   The calibration prototype has a parallel plate with high transparency, one of which is flat on the entire surface and the other of which has a plurality of steps parallel to the opposite surface. 5. The calibration apparatus for a measuring apparatus according to claim 4, wherein the reflector is subjected to reflection processing.   5. The measurement according to claim 4, wherein an alignment mark is formed on one surface of a parallel plate having a plurality of flat portions having different steps on both surfaces, and the other surface is subjected to reflection processing. Equipment calibration device.   Combining a plurality of plates having the same refractive index with the calibration master, one of which is a flat surface on the entire surface, and the other is a highly transparent parallel plate having a plurality of uneven surfaces parallel to the opposite surface. 5. The calibration apparatus for a measuring apparatus according to claim 4, wherein the alignment mark is processed, and reflection processing is applied to a plurality of flat portions at different levels.   Combining a plurality of plates with the same refractive index into the calibration prototype, creating a highly transparent parallel plate with one surface being flat and the other being stepped parallel to the opposite surface. 5. The calibration apparatus for a measuring apparatus according to claim 4, wherein an alignment mark is processed in the portion, and a reflection processing is applied to the entire flat surface portion.   Combining a plurality of plates with the same refractive index, creating a parallel plate with a plurality of flat portions with different steps on both sides, processing the alignment mark on one side, and reflecting the other side The calibration apparatus for a measuring apparatus according to claim 4.   3. The calibration apparatus for a measuring apparatus according to claim 2, wherein the calibration master creates a plurality of alignment marks on a circumferential surface of a highly transparent cylinder in a direction perpendicular to the cylinder axis.   3. The calibration apparatus for a measuring apparatus according to claim 2, wherein the calibration master creates a circular alignment mark on a circumferential surface of a highly transparent cylinder in a direction perpendicular to the cylinder axis.

Images