JP2006106163A - Optical element holding structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lens holding structure capable of reducing errors concerning the position and the inclination of an optical axis. <P>SOLUTION: A base 21 demarcates a bearing surface 23 surrounding a through-hole part 22 and the opening of the through-hole part 22. A lens barrel 24 holding a lens group inside is fit in the through-hole part 22. A lens barrel 24 demarcates a fitting side surface 241a facing to the inner side surface 22a of the through-hole part 22 and a flange surface 242a facing to the bearing surface 23. An O-ring 27 intervenes between the fitting side surface 241a and the inner side surface 22a. According to the number of shims 25 intervening between the bearing surface 23 and the flange surface 242a, the posture of the lens barrel 24 is adjusted so that the inclination of the flange surface 242a to the bearing surface 23 may be changed, and the lens barrel 24 is fixed on the base 21 by a bolt 26 so that the posture of the lens barrel 24 after adjustment may be maintained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a holding structure for optical elements such as lenses and mirrors, and more particularly to a holding structure suitable for holding a lens that transfers a pattern formed on a mask onto a substrate.

  FIG. 6 is a cross-sectional view showing a conventional lens holding structure (see Patent Document 1). A base 2 is arranged on the surface plate 1. A through hole 2a is formed in the base 2, and the lens barrel 3 is fitted in the through hole 2a. The lens barrel 3 holds a plurality of lenses 4 arranged in the depth direction of the through hole 2a therein. Laser light L emitted from a light source (not shown) is incident on a mask 5 on which a pattern to be transferred (hereinafter referred to as a mask pattern) is formed, and the laser light L passing through the mask 5 is a group of lenses 4 in the lens barrel 3. And enters the substrate W. As a result, the mask pattern is transferred to the substrate W.

JP 2003-142396 A (FIG. 1)

  For example, in order to accurately transfer the mask pattern to a desired position on the surface of the substrate W, the spatial position of the optical axis S of the projection optical system constituted by the lens 4 group in the lens barrel 3 is an ideal ideal. It is necessary to be kept in a proper position. However, in the conventional holding structure, there is room for improvement with respect to improving the reproducibility of the position of the optical axis S. For example, when the lens barrel 3 is once removed for exchanging the lens 4, the optical axis The position of S sometimes deviated from the ideal position. Here, generally, the deviation of the position of the optical axis from the ideal position is referred to as a “position error”.

  In addition, it is desirable that the optical axis S is perpendicular to the surface of the substrate W. However, since the manufacturing accuracy of the base 2 and the lens barrel 3 is limited, the optical axis S may not be perpendicular to the surface of the substrate W in the conventional holding structure. Here, generally, the inclination of the optical axis from the normal of the substrate surface is referred to as “inclination error”.

  An object of the present invention is to provide an optical element holding structure capable of reducing a position error and a tilt error. Another object of the present invention is to realize an optical element holding structure capable of reducing a position error and a tilt error with a simple configuration.

  According to one aspect of the present invention, a base that defines a hole and a seating surface that surrounds the opening of the hole, and a holding body that fits into the hole, the holding body being fitted into the hole. Sometimes a holding side surface defining a fitting side surface facing the inner side surface of the hole and a flange surface facing the seating surface, an optical element held by the holding body, an inner side surface of the hole portion, and the In contact with the fitting side surface of the holding body, the inclination of the flange surface with respect to the seating surface changes with the elastic body interposed between both surfaces and the holding body fitted in the hole. And a fixing member that can fix the holding body to the base so that the attitude of the holding body after the adjustment can be maintained. A retaining structure is provided.

  It is prevented by the elastic repulsive force of an elastic body that a holding body moves to the facing direction of the fitting side surface and the inner surface of a hole. For this reason, the reproducibility of the position of the optical axis of the optical element held by the holding body can be improved, and the occurrence of a position error can be prevented. On the other hand, since the elastic body can be deformed, the distance between the fitting side surface and the inner side surface of the hole is variable. As a result, the posture of the holding body can be adjusted so that the inclination of the flange surface with respect to the seating surface changes. Therefore, even if an inclination error occurs due to a manufacturing error of the base or the holding body, the posture of the holding body can be adjusted so as to correct the inclination error, so that the inclination error can be reduced. it can.

  FIG. 4 is a cross-sectional view showing a lens holding structure according to a trial example. Prior to the description of the embodiment, a trial example will be described first. The base 11 defines a through hole portion 12 and a seating surface 13 surrounding the opening of the through hole portion 12. The lens barrel 14 has an inlay portion 141 and a flange portion 142.

The inlay portion 141 fits into the through hole portion 12. The inlay portion 141 defines a fitting side surface 141 a that faces the inner side surface 12 a of the through hole portion 12 when fitted in the through hole portion 12. A fitting side 141a, but a gap G ₁ is being secured between the inner surface 12a of the through hole 12, the barrel 14 parallel to the seating surface 13 (e.g., horizontal direction in FIG. 4) When moved by a predetermined amount or more, the fitting side surface 141a comes into contact with the inner side surface 12a. Thereby, the movement of the lens barrel 14 in the direction parallel to the seating surface 13 is restricted. In this trial examples were narrowed than the conventional gap G _1. Specifically, the difference between the inner diameter of the through hole portion 12 and the outer diameter of the spigot portion 141 was designed to be 10 μm. As a result, the movable range of the lens barrel 14 in the direction parallel to the seating surface 13 becomes smaller than in the prior art, so the reproducibility of the position of the optical axis S can be improved and the occurrence of misalignment can be prevented.

  The flange portion 142 defines a flange surface 142 a that faces the seat surface 13. In this trial example, the shim 15 is interposed between the seat surface 13 and the flange surface 142a, and the flange portion 142 is used as a base by the bolt 16 so that the shim 15 is sandwiched between the seat surface 13 and the flange surface 142a. The structure fixed to 11 was taken. Although only two bolts 16 are shown in FIG. 4, two or more bolts 16, specifically three, are arranged in the circumferential direction of the flange portion 142. A plurality of shims 15 are discretely arranged in the circumferential direction of the flange portion 142.

  By adjusting the number of shims 15 inserted and the insertion position, the posture of the lens barrel 14 can be adjusted so that the inclination of the flange surface 142a with respect to the seating surface 13 changes. The lens barrel 14 can be fixed to the base 11 with the bolts 16 so that the post-adjustment posture of the lens barrel 14 is maintained. For this reason, even if an inclination error due to a manufacturing error of the lens barrel 14 or the base 11 occurs, the inclination of the optical axis S can be adjusted so as to correct the inclination error. For this reason, an inclination error can be reduced. The distance (hereinafter referred to as a work distance) WD from the end surface 14a of the lens barrel 14 facing the substrate W to the surface of the substrate W can be adjusted by the number of shims 15 inserted.

However, in this trial example, for example, the following new problems were found. First, when the narrowing of the gap G _1, although capable of improving the reproducibility of the position of the optical axis S, fitting work of fitting portions 141 into the through hole 12 becomes difficult. For this reason, the ease of maintenance such as the replacement work of the lens barrel 14 is impaired.

  In addition, there is room for improvement in terms of facilitating the operation of adjusting the number of inserted shims 15. This will be specifically described. In order to adjust the number of shims 15 to be inserted, the bolts 16 must be loosened to ensure a gap between the flange surface 142a and the already inserted shims 15. Since the flange surface 142a and the seating surface 13 face each other in the direction of gravity, the lens barrel 14 can be lifted to secure a gap between the flange surface 142a and the already inserted shim 15. is necessary. In this regard, when the weight of the lens barrel 14 is about 40 kg or more, for example, it may be assumed that adjustment of the number of inserted shims 15 becomes difficult.

Although the tilt adjustment function of the lens barrel 14 is provided as described above, it is difficult to say that the adjustment range is sufficient. This, when narrowing the gap G _1, alone slightly tilted lens barrel 14, the socket portion 141 contacts the inner surface 12a of the through hole 12, which further inclination of the lens barrel 14 is prevented by This is because that. The more narrow the width of the gap G _1, the range of inclination adjustment becomes smaller.

  FIG. 5 schematically shows a state in which the inlay portion 141 is in contact with the inner side surface 12 a of the through hole portion 12. The lens barrel 14 can be inclined with respect to the seating surface 13 by adjusting the number of shims 15 inserted. However, as the inclination is increased, the inlay portion 141 comes into contact with the inner side surface 12a of the through hole portion 12, so that the lens barrel 14 cannot be inclined further. In addition, when the bolt 16 is tightened in such a state, even if the bolt 16 is subsequently loosened, the inlay portion 141 may engage with the base 11 and the lens barrel 14 may not move.

Returning to FIG. 4, the description will be continued. On the other hand, without the width of the gap G ₁ is changed, as a method of expanding the adjustment range of inclination of the lens barrel 14, the socket portion 141, to reduce the height D ₁ of the depth direction of the through hole 12 Conceivable. The lower the height D ₁ of the spigot portion 141, it is possible to enlarge the inclination adjustment range of the lens barrel 14. However, lowering the height D ₁ of the spigot portion 141, so that another problem that the socket portion 141 tends to escape through the through hole 12 occurs.

This will be specifically described. Now, it is assumed that the height D _{h of the} portion of the inlay portion 141 fitted in the through hole portion 12 is 2 mm. In order to adjust the work distance WD, it is considered that the lens barrel 14 is moved in the vertical direction depending on the number of shims 15 inserted. A desired adjustment range of the work distance WD is determined by an attachment error of a lens arranged in the lens barrel 14 and is, for example, ± 3 mm. Now, assume that the number of shims 15 inserted is increased to increase the work distance WD by 3 mm, and the lens barrel 14 is moved upward by 3 mm. Then, since _{D h} is less than 2 mm, the socket portion 141 comes off from the through hole 12.

  In a state where the inlay portion 141 has come out of the through hole portion 12, the inner surface 12a of the through hole portion 12 does not restrict the movement in the direction parallel to the seating surface 13 of the lens barrel 14, so that the position error Cause the occurrence of As a result of further investigation based on the knowledge described above, the inventor has devised a lens holding structure described below.

  FIG. 1 is a cross-sectional view illustrating a lens holding structure according to an embodiment. The base 21 defines a through hole portion 22 and a seat surface 23 that surrounds the opening of the through hole portion 22. The seat surface 23 is defined on the back surface of the base 21 (the lower surface with respect to the direction of gravity action). The lens barrel 24 has an inlay portion 241 that defines a fitting side surface 241 a that faces the inner side surface 22 a of the through hole portion 22, and a flange portion 242 that defines a flange surface 242 a that faces the seat surface 23. A shim 25 is interposed between the seating surface 23 and the flange surface 242a, and the flange portion 242 is fixed to the base 21 with bolts 26 so that the shim 25 is pinched by the seating surface 23 and the flange surface 242a.

  In the present embodiment, the base 21 and the lens barrel 24 are arranged on the condition that the flange surface 242a is positioned below the seating surface 23 with respect to the direction of gravity action. That is, the inlay portion 241 is inserted into the through hole portion 22 from the back surface side of the base 21. Thereby, the distance between the seat surface 23 and the flange surface 242a is increased by the weight of the lens barrel 24 only by loosening the bolt 26. The distance between the seat surface 23 and the flange surface 242a can be adjusted by adjusting the looseness of the bolt 26. For this reason, it is possible to easily insert the shim 25 and adjust the number of inserted sheets.

In this embodiment, the O-ring 27 is interposed between the fitting side surface 241 a of the spigot part 241 and the inner side surface 22 a of the through hole part 22. The O-ring 27 is fitted in a groove formed in the fitting side surface 241a so as to extend in the circumferential direction, and surrounds the spigot part 241 over the entire circumference. The O-ring 27 is disposed in contact with the fitting side surface 241a and the inner side surface 22a. Thereby, the movement of the lens barrel 24 in the facing direction between the fitting side surface 241 a and the inner side surface 22 a is prevented by the elastic repulsive force of the O-ring 27. Therefore, the gap G ₂ between the mating sides 241a and the inner side surface 22a be designed larger than the gap G ₁ of FIG. 4, can improve the reproducibility of the position of the optical axis S, prevent the occurrence of the position error it can. Further, it is possible to increase design than the gap G ₁ of FIG. 4 the gap G _2, it is easy to fit the work into the through hole 22 of the lens barrel 24.

On the other hand, since the O-ring 27 can be elastically deformed, the posture of the lens barrel 24 can be adjusted so that the inclination of the flange surface 242a with respect to the seating surface 23 changes. As described above, since the gap _{G 2} between the mating sides 241a and the inner surface 22a can be made larger design than the gap _{G 1} of FIG. 4, without reducing the height _{D 2} of the fitting portions 241, the lens barrel 24 A sufficient tilt adjustment range can be secured. For this reason, the inclination error of the optical axis S can be reduced. In addition, since the height from the flange surface 242a to the O-ring 27 can be sufficiently secured, the O-ring 27 can be prevented from coming off from the through hole portion 22.

A specific example will be described. The height _{D 2} of the spigot portion 241 was 13.5 mm. Also, the height _{D 2a} from the flange face 242a and the lower surface of the O-ring 27 was set to 7.5 mm. Here, the lower surface of the O-ring 27 refers to an end surface of the O-ring 27 on the flange surface 242a side. As a result, the work distance WD can be increased or decreased by 3 mm while the inlay portion 241 is fitted in the through hole portion 22.

  Further, the difference between the inner diameter of the through hole portion 22 and the outer diameter of the spigot portion 241 was designed to be 0.5 mm. Specifically, the inner diameter of the through hole portion 22 was 220.5 mm, and the outer diameter of the spigot portion 241 was 220 mm. The width F in the radial direction of the flange portion 242 was 20 mm. As a result, the optical axis S can be inclined by about 0.14 ° or more with respect to the reference axis. Here, the reference axis refers to the optical axis S defined when no shim 25 is inserted. That is, it is possible to correct a tilt error of about 0.14 ° or more. Although the inner diameter of the through hole portion 22 is 0.5 mm larger than the outer diameter of the spigot portion 241, the occurrence of a position error of the optical axis S is prevented by the elastic repulsive force of the O-ring 27.

  As described above, the holding structure according to the present embodiment can be realized with a simple configuration in which the O-ring 27 is interposed between the fitting side surface 241a and the inner side surface 22a, and the position error of the optical axis S can be reduced. This produces the effects of preventing the occurrence and ensuring a wide tilt adjustment range of the optical axis S. Even if the lens barrel 24 is inserted into the through-hole portion 22 from above the base 21, the above effect can be obtained. The holding structure according to the present embodiment uses, for example, a mask in which pinholes are formed corresponding to the mask 5 in FIG. 6, and the pinholes of the mask are connected to the surface of the substrate W using a lens group in the lens barrel 24. It can be applied to drilling to be imaged.

  FIG. 2 is a cross-sectional view showing a mirror holding structure according to another embodiment. The base 31 defines a bottomed hole portion 32 and a seating surface 33 surrounding the opening of the bottomed hole portion 32. A holding body 34 holding the mirror M is fitted in the bottomed hole portion 32. The holding body 34 defines a fitting side surface 35 that faces the inner side surface 32 a of the bottomed hole portion 32, and a flange surface 36 that faces the seat surface 33. A shim 37 is interposed between the seating surface 33 and the flange surface 36, and the holding body 34 is fixed to the base 31 by bolts 38 so that the shim 37 is pinched by the seating surface 33 and the flange surface 36. Two or more bolts 38 are arranged in the circumferential direction of the flange surface 36, specifically three. A plurality of shims 37 are discretely arranged in the circumferential direction of the flange surface 36.

  An O-ring 39 is interposed between both surfaces in contact with the fitting side surface 35 and the inner side surface 32a of the bottomed hole portion 32. The O-ring 39 surrounds the fitting side surface 35 over the entire circumference. Since the O-ring 39 can be elastically deformed, by adjusting the difference in thickness between the shims 37, the posture of the holding body 34 can be adjusted so that the inclination of the flange surface 36 with respect to the seating surface 33 changes. Thereby, the mirror M can be raised in two orthogonal directions. In addition, the holding body 34 can be fixed to the base 31 with the bolts 38 so that the adjusted posture of the holding body 34 is maintained. For this reason, for example, since the spatial position of the reflected optical axis of the laser light incident on the mirror M can be adjusted, an error relating to the spatial position of the optical axis can be corrected.

  FIG. 3 shows a conventionally used mirror holding structure. FIG. 3A is a cross-sectional view of the mirror structure. The mirror structure is configured by the mirror M being fixedly attached to the holder 41. In this case, the structure shown in FIG. 3B is necessary in order to allow the mirror M to be raised in two orthogonal directions. FIG. 3B is a schematic view of a two-axis tilt mechanism. The first shaft 43 is supported by the U-shaped member 42, and the holder 41 is supported by the first shaft 43. The holder 41 can rotate around the first shaft 43. The U-shaped member 42 is supported by a second shaft 44 that extends in a direction orthogonal to the first shaft 43. The U-shaped member 42 can rotate around the second axis 44. Compared to such a mechanism, the holding structure shown in FIG. 2 can be realized compactly with a simple configuration.

  As mentioned above, although the Example was described, this invention is not limited to this. In the embodiment, the O-ring is used as the elastic body. However, the O-ring is not limited to the O-ring, and a material that exhibits elasticity in the facing direction between the inner side surface of the hole and the fitting side surface of the holding body can be widely used. Further, in the embodiment, an annular member that surrounds the fitting side surface of the holding body over the entire circumference is used as the elastic body, but a plurality of elastic bodies may be discretely arranged in the circumferential direction of the fitting side surface. Good. In addition, in order to prevent the shim insertion position from shifting, one of the flange surface and the seat surface is provided with a projection shaft that is fitted toward the other, and the shim having a through hole is formed. You may make it interpose between a flange surface and a seat surface in the state penetrated by the axis | shaft. The optical element to be held is not particularly limited to a lens or a mirror, and a window, a prism, a diaphragm, or the like can also be held. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is sectional drawing which shows the holding structure of the lens by an Example. It is sectional drawing which shows the holding structure of the mirror by an Example. It is the schematic which shows the holding structure of the mirror by a prior art. It is sectional drawing which shows the holding structure of the lens by a trial example. It is sectional drawing which shows the holding structure of the lens by a trial example. It is sectional drawing which shows the holding structure of the lens by a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical surface plate, 2 base, 2a ... Through-hole part, 3 ... Lens tube, 4 ... Lens (optical element), 5 ... Photomask, L ... Laser beam, S ... Optical axis, W ... Substrate, 11, 21 ... Base, 12, 22 ... Through-hole part (hole part), 12a, 22a ... Inner side surface, 13, 23 ... Seat surface, 14, 24 ... Lens barrel, 141, 241 ... Inlay part, 142, 242 ... Flange part, 142a, 242a ... flange surface, 15, 25 ... shim, 16, 26 ... bolt, 27 ... O-ring (elastic body), 31 ... base, 32 ... bottomed hole (hole), 32a ... inner surface, 33 ... Seat surface, 34 ... holding body, 35 ... fitting side surface, 36 ... flange surface, 37 ... shim, 38 ... bolt, 39 ... O-ring (elastic body), M ... mirror (optical element).

Claims (5)

A base defining a hole and a seating surface surrounding the opening of the hole;
A holding body that fits into the hole portion, and defines a fitting side surface that faces the inner side surface of the hole portion and a flange surface that faces the seat surface when the holding body is fitted into the hole portion. Holding body,
An optical element held by the holding body;
An elastic body interposed between both surfaces in contact with the inner side surface of the hole and the fitting side surface of the holding body;
With the holding body fitted in the hole, the posture of the holding body can be adjusted so that the inclination of the flange surface with respect to the seating surface changes, and the posture of the holding body after adjustment is An optical element holding structure comprising: a fixing member capable of fixing the holding body to the base so as to be maintained.   The holding structure according to claim 1, wherein the elastic body is configured by an O-ring that surrounds the fitting side surface of the holding body over the entire circumference. The optical element includes a plurality of lenses;
The said holding body is extended by the axial direction which cross | intersects the said seat surface, and is comprised by the cylinder which hold | maintains the said some lens in the state arranged in the said axial direction inside. Retaining structure. The fixing member is
A shim interposed between the flange surface and the seat surface;
The holding structure according to any one of claims 1 to 3, further comprising a plurality of bolts that fix the holding body to the base so that the shim is pinched by the flange surface and the seating surface.   On the condition that the base and the holding body have a positional relationship in which the seat surface and the flange surface face each other in the gravitational action direction, and the flange face is disposed below the seat face with respect to the gravitational action direction. The holding structure according to any one of claims 1 to 4, wherein the holding structure is arranged.

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