JPH03200111A - Assembled lens - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) (Prior Art) Projection lenses used in exposure equipment for semiconductor devices are required to have extremely small aberrations. The precision of the lens spherical surface is required to be around λ/20, and the precision of the assembly is high enough to keep errors in tilt and shift, which are the deviations of each lens from the optical axis, and in the distance between lenses to within a few μm. Accuracy is required.

Conventionally, as shown in FIG. 5, a conventional method for assembling a plurality of lenses so that their optical axes coincide with each other includes providing a step 30 on the lens barrel 3 for receiving the spherical outer circumferential portion of the lens, and attaching the lens 1 to the step 30 by attaching the ring-shaped push screw 4 to the lens barrel 3. There is a way to tighten it. In this method, a gap is provided between the lens outer peripheral cylindrical surface 1c and the lens barrel inner surface 34 so that the lens 1 can be fitted, and the guiding effect by the spherical surfaces 1a and 1b on both sides of the lens 1 itself, that is, the stepped edge 30a. and the edge 4a of the push screw are fixed such that the distance between them is minimized. However, since the accuracy of the step machining on the inner diameter of the lens barrel cannot be very high, in this method, if the push screw is tightened strongly, the contact between the lens spherical surfaces 1a and lb, the step edge 30a, and the push screw edge 4a may be uneven. Therefore, lens 1 will be distorted, and if the tightening is too weak, lens spherical surface 1 will be distorted.
There is a problem in that the screws cannot be positioned at the correct position due to friction between the step edges 30a and the push screw edges 4a. That is, the above method basically has a problem arising from the fact that the reference part for assembly is provided inside the lens barrel, where it is difficult to achieve machining accuracy.

There is also a method of assembling a lens by tightly fitting a lens A with a metal frame as shown in FIG. 7 into the inner surface 34 of the lens barrel 3 as shown in FIG. In this case, the lens 1 is fixed in the metal frame 5 with an eyepiece 51, and in this situation, the outer cylindrical surface of the metal frame 5
2 is a perfect circle with respect to the optical axis 100 of the lens 1, and the end surface 23.
24 is additionally machined so that it is vertical and its outer diameter is very slightly smaller than the inner diameter of the lens barrel 3, and is assembled by fitting it to the inner diameter of the lens barrel 3, and the distance between adjacent lenses is as follows.
Positioned by spacing rings 71,72.

In this method, the cylindricity (roundness and straightness) of the inner surface of the lens barrel
It is necessary to process the lens barrel with extremely high precision, for example, using a special processing machine for the inner circumference of the lens barrel, and the outer cylindrical surface 22 of the metal frame must also be a perfect circle with respect to the lens optical axis 100. Since the dimensions need to be extremely small compared to the inner diameter of the lens barrel, the outer periphery must be processed with extremely small cuts on the order of 1 μm. Therefore, this method has a problem in that the smaller the fitting gap and the higher the precision, the more difficult the assembly work is.

(Problems to be Solved by the Invention) An object of the present invention is to provide an assembled lens that can be assembled with high assembly accuracy and that is easy to assemble.

(Means for Solving the Problems) The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention.

That is, the present invention provides an assembled lens in which a plurality of lenses are fixed in a lens barrel at positions where their optical axes coincide, in which the plurality of lenses are stacked in the lens barrel via a spacing ring, and the plurality of lenses and The position of the spacing ring is fixed using the outer circumferential surface of the lens barrel or at least three spacers provided by processing the outer circumferential surface and having a plane perpendicular to the cylindrical axis of the lens barrel as a reference plane, and the distance between the plurality of lenses and the spacer is fixed. An assembled lens characterized in that a ring is fixed in the axial direction of the lens barrel using end plates fastened to each end of the lens barrel, thereby fixing a plurality of lenses in the m-tube at positions where their optical axes coincide. It is.

(Function) In the assembled lens of the present invention, a plurality of lenses are laminated via a spacing ring, and the plurality of lenses and the spacing ring are provided by processing the outer peripheral surface or the outer peripheral surface of the lens barrel, and the lens barrel has a cylindrical shape. Since it is positioned by a spacer that has a plane perpendicular to the axis as the reference plane, it can be assembled with high precision by processing the cylindricity (R circularity and straightness) of the outer cylindrical part of the lens barrel to be used with high precision. . Further, since the outer cylindrical portion of the lens barrel can be processed more easily than the inner surface of the lens barrel that was performed in conventional assembly, the assembled lens of the present invention can be easily assembled.

(Examples) The present invention will be described below based on Examples, but the present invention is not limited thereto.

FIG. 1 is a sectional view showing an example of the structure of an assembled lens according to the present invention, which was assembled in the following steps.

First, the spacing ring 71 is placed on the end plate 31, the lens 11 is placed on top of this, and then the spacing ring 72 and the lens 12 are stacked in the same way until the spacing ring 75 is stacked, and then the lens barrel 3 is placed on the outside of these. Then, the lens barrel 3 and end plate 31 were fastened together using screws (not shown). Thereafter, the spacing ring 71 is positioned using the spacers 41 (located at three equal positions on the circumference of the lens barrel) so that its axial center coincides with the axis of the outer cylindrical surface] 00, which is the reference for assembling the lens barrel 3. Then, the lens 11 was similarly positioned and fixed using the spacer 42. Similarly, all lenses 11 to 14 and spacing rings 71 to 75
Then, the end plate 32 was screwed to the lens barrel 3 to complete the assembly.

In this embodiment, the spacing rings 71 and 75 each have parallel end surfaces of a predetermined height, and the edge-side cylindrical surface in contact with the lens spherical surface and the outer cylindrical surface are finished to have a high degree of concentricity. I used something. In addition, each lens was finished so that the outer circumferential portion thereof had a cylindrical surface centered on the optical axis 100.

In the present invention, a lens with a metal frame shown in FIG. 7 can also be used as the lens. In this case, the outer peripheral cylindrical surface 22 of the metal frame is finished as a cylindrical surface centered on the optical axis 100, and both end surfaces are finished. 23 and 24 are finished so that their surfaces are parallel and perpendicular to the optical axis 100. In addition, when assembling, the spacing ring is in contact with the end face of 23.24,
The outer cylindrical surface 22 of the metal frame is in contact with the spacer.

Next, a positioning and fixing method for aligning the axes of the lenses 11 to 14 and the spacing rings 71 to 75 with the axes of the non-standard cylindrical surface 301 of the lens barrel 3 will be explained in FIG.
- cross-section). First, two of the three spacers 44 are inserted into the through hole 303, and with each spacer in contact with the abutting plate 441, the outer peripheral surface of the lens barrel 3 is machined along the axis using the screws 442. It is fixed in close contact with the obtained plane 302. At this time, the spacer 44 and the through hole 303 are fitted with no looseness, thereby making it possible to assemble with high precision. Next, the lens 12 is passed through the through hole 303 into which the third spacer 44 should be inserted, and the lens 12 is lightly pressed against the lens support 44a of the spacer 44, and in this state, the lens 12 is inserted through the three through holes 303 into which the spacer is not inserted, using a depth micrometer to measure the cylindrical surface 301 as a reference. The distance to the outer cylindrical surface 12c of the lens 12 was measured. At this time, if the distances at all three locations are equal, the lens axis is aligned with the axis of the outer cylindrical surface of the lens barrel, so insert the third spacer 44 and press it against the lens. After modifying the spacer length so that the tip 44b is flush with the flat surface 302, the abutting plate 44 is flattened with screws 442.
It was fixed in close contact with 02. On the other hand, three through holes 30
When all the distances at 3 are constant boundaries, the deviation of the axis of the lens] 2 is calculated based on the measured value, and the two spacers 44 inserted earlier are corrected to correct this.

FIG. 3 is a diagram showing another embodiment of the present invention.

This embodiment is assembled by inserting outer rings 701 to 704 into the outer periphery of the lens, and a perspective view of the outer rings 701 to 704 is shown in FIG. The outer ring has six holes 7011 for passing through the spindle of a depth micrometer for the spacer 44 and for determining the lens outer circumference flPI. In the case of FIG. 3, for example, the lens 11 has the upper end surface edge 71a of the spacer ring 7.
The height of the outer circumferential ring 701 is adjusted so as to maintain a slight gap (within 10 μm) between it and the lower end surface edge 72b of the spacing ring 72. Below, lenses 12, 13゜1
4, only the lower surface of the lens is supported by the upper end surface edges 72a, 73a, and 74a of the lower spacing ring. Therefore, since only the weight of the lens is applied to the support point, distortion of the lens due to the stacked weight does not occur. In addition, in this case, since the lens can be adjusted independently, the lens outer cylindrical surface 11
It can also be applied to assembly when c to 14c have a non-negligible roundness error with respect to the optical axis 100.

Parts other than the lens used in the above embodiments include the lens barrel 3, spacing rings 71 to 75, end plates 31 and 32, and outer rings 701 to 7.
04, spacers 41 to 49.

For '1ltta3, these machining accuracies are based on the cylindricity (roundness and straightness) of the outer cylindrical surface 301 and the axis 1 of both end surfaces.
The orthogonality with 00, and the cylindricity is obtained by cylindrical grinding,
Orthogonality can be achieved by surface grinding or surface lapping. The concentricity of the inner and outer surfaces of the spacing rings 71 to 75 can be achieved by precision turning or a combination of cylindrical grinding and internal grinding. The parallel planes of the spacing rings 71 to 75, the outer ring, and the end plate can be processed by surface grinding or parallel plane lapping.

All of these precisions can be achieved within 2 to 3 μm. It is also possible to modify the spacers 41 to 49 to an order of 1 μm. That is, the component parts of the present invention are:
The required precision can be achieved using general-purpose processing methods and processing equipment without using special processing methods and equipment.

In addition, the assembly work in the implementation of the present invention has clear methods and procedures, and there are no parts that are difficult to work or rely on intuition.As a result of the comprehensive performance test after assembly, even when performing j + Il repair again, The structure allows for easy disassembly and reassembly.

(Effects of the Invention) As described above, the assembled lens of the present invention can be assembled with high precision by using only parts that can obtain the required precision by ordinary processing methods and by easy assembly work. . In addition, repeating disassembly and reassembly is easy and reproducible, so adjustments can be easily made by modifying the corresponding parts (for example, spacers) based on the comprehensive test results of the assembled lens.

[Brief explanation of drawings]

FIGS. 1 and 3 are longitudinal sectional views showing embodiments of the assembled lens of the present invention. FIG. 2 is a cross-sectional view taken along line A-A'' in FIG. 1 of the assembled lens according to the embodiment of the present invention. FIG. 4 is a perspective view of the outer ring used in the embodiment shown in FIG. 3. 5 and 6 are cross-sectional views showing parts of a conventional assembled lens. FIG. 7 is a cross-sectional view showing a lens with a metal frame. In the figures, 1.11 to 14...lens la , lb... Lens spherical surface 1c, 11c to 14c... Lens outer peripheral cylindrical surface 3...
Lens barrel 4...Ring-shaped push screw 4a...
・Edge of push screw 5... Metal frame 22... Metal frame outer periphery cylindrical surface 23.24... Metal frame end face 30... Step on inner surface of lens barrel 30a... Step edge 3
1.32... End plate 34... Lens barrel inner surface 41-4
9... Spacers 41a-49a... Spacer tips 41b-49b... Spacer rear end 51... Adhesion 71-75... Spacing ring 71
a~75a...m1 Upper end surface edge 71b~75 of the septum ring
b... Lower end surface edge of spacing ring 100... Optical axis
301... Lens barrel outer cylindrical surface 302... Plane of vL cylinder 303... Lens barrel through hole 441... Abutting plate 4
42... Screws 701 to 704... Each shows an outer peripheral ring. (No changes to the content written on the fP of the drawing) Figure 1

Claims (1)

[Claims] (1) In an assembled lens in which multiple lenses are fixed in a lens barrel at positions where their optical axes coincide, the multiple lenses are stacked in the lens barrel via a spacing ring, and the multiple lenses and the spacing ring are stacked together in the lens barrel. The position of the lens barrel is fixed using the outer circumferential surface of the lens barrel or at least three spacers provided by processing the outer circumferential surface and having a plane perpendicular to the cylindrical axis of the lens barrel as a reference plane, and the plurality of lenses and the spacing ring are fixed. An assembled lens characterized in that a plurality of lenses are fixed in the lens barrel at positions where their optical axes coincide by fixing in the lens barrel axial direction using end plates fastened to each end of the lens barrel.