JP7593777B2 - Objective lens - Google Patents

Description

The disclosure herein relates to an objective lens.

In microscope objective lenses, multiple lens assemblies are stacked inside the objective barrel and fixed inside the objective barrel by pressing the multiple lens assemblies against the objective barrel using a retaining ring. By firmly fixing the lens assemblies with the retaining ring, it is possible to prevent the lens assemblies from being displaced by external vibrations or impacts, and therefore to prevent deterioration of the objective lens' performance.

On the other hand, the pressure applied to the lens assembly by the pressing ring can deform the lens holding frame. Furthermore, deformation of the lens holding frame that constitutes the lens assembly can deform the lens fixed to the lens holding frame, resulting in distortion of the lens.

Technology related to this issue is described, for example, in Patent Document 1. The objective lens described in Patent Document 1 absorbs distortion by utilizing the deformation of a thin-walled portion provided in the lens holding frame. This makes it possible to reduce distortion of the lens caused by the pressing force generated by the pressing ring.

Japanese Utility Model Application Publication No. 7-26810

However, to ensure the necessary rigidity for the lens holder, the lens holder cannot be made infinitely thin. For this reason, there is a limit to the effect of reducing lens distortion that can be achieved by thinning the lens holder. In particular, it is difficult to sufficiently suppress lens distortion in lenses with thin cut end surfaces, where distortion occurs under relatively small stresses.

In light of the above-mentioned circumstances, an object of one aspect of the present invention is to provide an objective lens that can suppress lens distortion.

An objective lens according to one embodiment of the present invention comprises an objective barrel, a plurality of lens assembly sets arranged within the objective barrel, each of the plurality of lens assembly sets including at least a lens and a lens holding frame that holds the lens, and a pressing member fixed to the objective barrel, the pressing member pressing the plurality of lens assembly sets against the objective barrel along the optical axis direction of the objective lens, at least one of the plurality of lens assembly sets includes a first lens holding frame including an elastic member and a plurality of members fixed in a state in which the elastic member is sandwiched between the first lens holding frame and the objective lens further includes a second adhesive that bonds the first lens holding frame and the lens held by the first lens holding frame to each other, the elastic member being a first adhesive that bonds the plurality of members to each other, and the first adhesive having a lower elastic modulus than the elastic modulus of the second adhesive .

The above aspect provides an objective lens that can suppress lens distortion.

1 is a cross-sectional view of an objective lens 100 according to a first embodiment. FIG. 11 is a cross-sectional view of an objective lens 200 according to a second embodiment. FIG. 11 is a cross-sectional view of an objective lens 300 according to a third embodiment. FIG. 11 is a cross-sectional view of an objective lens 400 according to a fourth embodiment. FIG. 13 is a cross-sectional view of an objective lens 500 according to a fifth embodiment.

First Embodiment
Fig. 1 is a cross-sectional view of an objective lens 100 according to this embodiment. Fig. 1 shows a cross section of the objective lens 100 on a plane along an optical axis 1. The objective lens 100 shown in Fig. 1 is an objective lens for a microscope, and is, without being limited thereto, for example, an infinity-corrected objective lens that forms an enlarged image of a sample in combination with an imaging lens.

The objective lens 100 includes an objective barrel 110 and a number of lens assembly members (lens assembly member 121, lens assembly member 122, lens assembly member 123, lens assembly member 124, lens assembly member 125, and lens assembly member 126) arranged within the objective barrel 110 along the axial direction of the objective barrel 110. The objective lens 100 further includes a retaining ring 190 fixed to the objective barrel 110.

The objective barrel 110 is a cylindrical member having a cylindrical shape, and houses multiple lens assemblies inside. The axial direction of the objective barrel 110 is the direction along the central axis of the cylinder, and is approximately the same as the direction of the optical axis 1 of the objective lens 100. The material of the objective barrel 110 is not particularly limited, but is, for example, brass. The objective barrel 110 has a screw-type portion 111 on the outer surface of which a male screw is formed. The objective lens 100 is fixed to the microscope by screwing the screw-type portion 111 into the revolver of the microscope. The screw-type portion 111 is an example of a connection portion for connecting the objective lens 100 to the microscope. The method of connecting the objective lens 100 to the microscope is not limited to screwing, and other methods may be used.

Each lens assembly includes a lens (lens L1, lens L2, lens L3, lens L4, lens L5, lens L6) and a lens holding frame that holds the lens (lens holding frame 130, lens holding frame 140, lens holding frame 150, lens holding frame 160, lens holding frame 170, lens holding frame 180). The lens material is not particularly limited, but may be optical glass, for example. The lens and the lens holding frame are bonded to each other with an adhesive (not shown). The lens included in each lens assembly may be a single lens such as lens L1, or a cemented lens in which multiple lenses (lens L3a, lens L3b, lens L3c) are cemented together, such as lens L3.

The multiple lens subassemblies are stacked and arranged within the objective barrel 110 in the axial direction of the objective barrel 110, i.e., in the direction of the optical axis 1, and are fixed within the objective barrel 110 by a retaining ring 190.

The pressing ring 190 is an example of a pressing member fixed to the objective barrel 110. The material of the pressing ring 190 is not particularly limited, but is, for example, brass. The pressing ring 190 is screwed into a female thread formed on the inner surface of the objective barrel 110, and presses the multiple lens assembly against the objective barrel 110 (more specifically, the convex portion formed at the object side end of the objective barrel 110) along the direction of the optical axis 1 of the objective lens 100. The pressing ring 190 screwed onto the objective barrel 110 presses the multiple lens assembly (more specifically, the multiple lens holding frames) and applies a pressing force, so that the pressing ring 190 and the objective barrel 110 (the convex portion) hold the multiple lens assembly stacked in the objective barrel 110, and as a result, the multiple lens assembly is firmly fixed in the objective barrel 110.

On the other hand, if the lens holding frame is deformed by the pressure, the deformation may be transmitted to the lens, causing distortion of the lens. Therefore, in the objective lens 100 according to this embodiment, the configuration of the lens holding frame 180 constituting the lens assembly 126, which is located closest to the pressing ring 190 among the multiple lens assembly, has been devised.

The lens assembly 126 placed closest to the pressing ring 190 refers to the lens assembly that is fixed in a state where it is sandwiched between the pressing ring 190 and the other lens assembly 125, and is the lens assembly placed in a position closest to the pressing ring 190. Therefore, if there is no spacer or the like interposed, it is the lens assembly that directly contacts the pressing ring 190.

The reason for the special configuration of the lens holding frame 180 included in the lens assembly 126 located closest to the pressing ring 190 is that it is prone to deformation due to pressure, and it is assumed that this provides the greatest deformation suppression effect, which will be described later. However, the special configuration described below may also be applied to other lens holding frames, or may be applied to multiple lens holding frames. The configuration of the lens holding frame 180 is described in detail below.

In the objective lens 100, the lens holding frame excluding the lens holding frame 180 is composed of a single element, whereas the lens holding frame 180 is composed of a combination of multiple elements. More specifically, the lens holding frame 180, which is the first lens holding frame of the objective lens 100, includes an adhesive 183 and multiple members (fixed member 181, lens holding member 182) that are fixed with the adhesive 183 sandwiched between them.

The adhesive 183 is an example of an elastic member, and has a modulus of elasticity lower than that of the multiple members (the fixed member 181, the lens holding member 182). The adhesive 183 is a first adhesive that bonds the multiple members together. Note that an adhesive (not shown) also exists between the lens holding member 182 and the lens L6. This adhesive (not shown) is a second adhesive that bonds the lens holding member 182 and the lens L6 together. As shown in FIG. 1, it is desirable that the first adhesive and the second adhesive have a relationship in which the adhesive area of the first adhesive is larger than the adhesive area of the second adhesive. The material of the fixed member 181 and the lens holding member 182 is not particularly limited, but is, for example, brass.

In the objective lens 100 configured as described above, even if the fixed member 181 is deformed by the pressing force from the pressing ring 190, the adhesive 183 between the fixed member 181 and the lens holding member 182 can absorb the deformation. Therefore, the deformation of the lens holding frame 180 is not easily transmitted to the lens L6, and as a result, the distortion of the lens L6 can be sufficiently suppressed. Therefore, according to the objective lens 100, even if the lens assembly is firmly fixed using the pressing ring 190, the deterioration of optical performance caused by lens distortion can be avoided, and high imaging performance and polarization performance as designed can be maintained. In other words, it is possible to achieve both impact resistance and optical performance. In addition, by using the adhesive 183 as an elastic member, the material cost is lower and the assembly workability is improved compared to the case where a leaf spring or an elastic rubber ring is used as the elastic member. Therefore, the manufacturing cost can also be reduced.

In addition, by providing an elastic member (adhesive 183, which is the first adhesive) between the fixed member 181 and the lens holding member 182 in addition to the adhesive (second adhesive) that fixes the lens L6 to the lens holding member 182, it is possible to ensure sufficient space to absorb deformation regardless of the shape of the lens L6. Therefore, the above-mentioned effect can be achieved regardless of the shape of each lens that constitutes the objective lens 100. For example, in a lens assembly that includes a lens with a thin edge surface such as lens L6, not only is the lens itself prone to deformation, but the adhesive area of the second adhesive is small, so the effect of absorbing deformation with the second adhesive is also small. For this reason, the above-mentioned configuration that absorbs deformation within the lens holding frame is particularly effective.

Furthermore, by making the adhesion area of the adhesive 183 (first adhesive) larger than that of the second adhesive, a greater absorption effect can be expected. Therefore, deterioration of optical performance caused by lens distortion can be more reliably avoided.

Second Embodiment
Fig. 2 is a cross-sectional view of the objective lens 200 according to this embodiment. Fig. 2 shows a cross section of the objective lens 200 on a plane along the optical axis 1. The objective lens 200 shown in Fig. 2 is also an objective lens for a microscope, similar to the objective lens 100 shown in Fig. 1. The objective lens 200 is similar to the objective lens 100, except that the objective lens 200 includes a lens part set 223 instead of the lens part set 123, and includes a lens part set 226 instead of the lens part set 126.

The lens assembly 223 differs from the lens assembly 123 in that it includes a lens holding frame 250 instead of the lens holding frame 150. The lens holding frame 250 includes a leaf spring 253 and multiple members (fixed member 251, lens holding member 252) that are fixed while sandwiching the leaf spring 253. Note that the multiple members that are fixed while sandwiching the leaf spring 253 only need to fix the objective barrel 110 and the lens L3 so that they do not move while sandwiching the lens holding frame 250, and it is not necessary that the elements of the lens holding frame 250 (fixed member 251, lens holding member 252, leaf spring 253) are bonded to each other with an adhesive or the like. The leaf spring 253 is an example of an elastic member, and has a lower elastic modulus than the multiple members (fixed member 251, lens holding member 252).

Lens assembly 226 differs from lens assembly 126 in that it includes lens holding frame 280 instead of lens holding frame 180. Lens holding frame 280 includes elastic rubber ring 283, screw 284, multiple members (fixed member 281, lens holding member 282) that are fixed by screw 284 while sandwiching elastic rubber ring 283, and screw 284. Elastic rubber ring 283 is an example of an elastic member, and has a lower elastic modulus than the multiple members (fixed member 281, lens holding member 282).

In both the lens holding frame 250 and the lens holding frame 280, the elastic members (leaf spring 253, elastic rubber ring 283) are interposed between multiple members in the radial direction of the objective lens 200, but not in the axial direction. In other words, they are interposed only in the radial direction. The radial direction is the direction perpendicular to the optical axis of the objective lens 200.

Even with the objective lens 200 configured as described above, the elastic members (leaf spring 253, elastic rubber ring 283) absorb the deformation of the lens holding member caused by the pressing force of the pressing ring 190, and lens distortion can be suppressed. Therefore, like the objective lens 100, it is possible to achieve both impact resistance and optical performance.

In addition, while misalignment of the lens in the optical axis direction can significantly degrade optical performance, in the objective lens 200, the elastic member is interposed only in the radial direction of the multiple members, so that even if the elastic member expands or contracts due to temperature changes, movement of the lens in the optical axis direction can be prevented. Therefore, with the objective lens 200, in addition to the deterioration of optical performance caused by the pressing force of the pressing ring 190, the deterioration of optical performance caused by temperature changes can also be suppressed.

Furthermore, in the objective lens 200, the elastic member is interposed only in the radial direction of the multiple members, and not in the optical axis direction. Therefore, even if a portion of the elastic member in the circumferential direction expands or contracts due to a non-uniform temperature change, the lens holding member (lens holding member 252, lens holding member 282) tilts relative to the fixed member (fixed member 251, fixed member 281), and as a result, the optical axis is prevented from shifting. Therefore, according to the objective lens 200, in addition to the deterioration of optical performance caused by the pressing force of the pressing ring 190, the deterioration of optical performance caused by the tilt of the lens due to temperature change can also be prevented.

Third Embodiment
Fig. 3 is a cross-sectional view of an objective lens 300 according to this embodiment. Fig. 3 shows a cross section of the objective lens 300 in a plane along the optical axis 1. The objective lens 300 shown in Fig. 3 is also an objective lens for a microscope, similar to the objective lens 100 shown in Fig. 1. The objective lens 300 is similar to the objective lens 100, except that it includes a lens assembly 326 instead of the lens assembly 126.

Lens assembly 326 differs from lens assembly 126 in that it includes lens holding frame 380 instead of lens holding frame 180. Lens holding frame 380 includes adhesive (adhesive 384, adhesive 385) and multiple members (fixed member 381, lens holding member 382, intermediate member 383) that are fixed with the adhesive sandwiched between them. More specifically, adhesive 384 is interposed radially between fixed member 381 and intermediate member 383, and bonds fixed member 381 and intermediate member 383 to each other. Adhesive 385 is interposed radially between intermediate member 383 and lens holding member 382, and bonds intermediate member 383 and lens holding member 382 to each other.

Even with the objective lens 300 configured as described above, the elastic member (adhesive 384, adhesive 385) absorbs the deformation of the lens holding member caused by the pressing force of the pressing ring 190, and lens distortion can be suppressed. Therefore, like the objective lens 100, it is possible to achieve both impact resistance and optical performance.

In the objective lens 300, the lens holding frame 380 includes an intermediate member 383, which is sandwiched by adhesive (adhesive 384, adhesive 385). By configuring the lens holding frame 380 in this manner, even if the deformation of the fixed member 381 due to the pressing force from the pressing ring 190 cannot be absorbed by the adhesive 384 between the fixed member 381 and the intermediate member 383, it can be absorbed by the adhesive 385 between the intermediate member 383 and the lens holding member 382. Therefore, according to the objective lens 300, it is possible to further reduce the distortion of the lens compared to when the lens holding frame has only one elastic member. Therefore, the configuration of this embodiment is particularly suitable for a lens holding frame for lenses with low rigidity, such as lenses with thin edge surfaces.

In addition, in the objective lens 300, the elastic member is interposed only in the radial direction of the multiple members, so that even if the elastic member expands or contracts due to a temperature change, the lens can be prevented from moving in the optical axis direction. Therefore, according to the objective lens 300, in the same way as the objective lens 200, in addition to the deterioration of optical performance caused by the pressing force of the pressing ring 190, the deterioration of optical performance caused by temperature changes can also be suppressed.

Fourth Embodiment
Fig. 4 is a cross-sectional view of an objective lens 400 according to this embodiment. Fig. 4 shows a cross section of the objective lens 400 on a plane along the optical axis 1. The objective lens 400 shown in Fig. 4 is also an objective lens for a microscope, similar to the objective lens 100 shown in Fig. 1. The objective lens 400 is similar to the objective lens 100, except that it includes a lens assembly 426 instead of the lens assembly 126.

The lens assembly 426 differs from the lens assembly 126 in that it includes a lens holding frame 480 instead of the lens holding frame 180. The lens holding frame 480 differs from the lens holding frame 180 in that it includes an adhesive 481 having a different elastic modulus from the adhesive 183 between the lens L6 and the lens holding member 182. The adhesive 481 is a second adhesive that bonds the lens holding member 182 and the lens L6 to each other, and has a higher elastic modulus than the adhesive 183. That is, the first adhesive and the second adhesive are in a relationship in which the first adhesive has a lower elastic modulus than the second adhesive. More specifically, the adhesive 183 is, for example, a silicone-based adhesive, and the adhesive 481 is, for example, an epoxy-based adhesive. Furthermore, it is desirable that the first adhesive and the second adhesive are in a relationship in which the adhesive area of the first adhesive is larger than the adhesive area of the second adhesive, as shown in FIG. 4.

Even with the objective lens 400 configured as described above, the elastic member (adhesive 183) absorbs the deformation of the lens holding member caused by the pressing force of the pressing ring 190, and lens distortion can be suppressed. Therefore, like the objective lens 100, it is possible to achieve both impact resistance and optical performance.

In addition, in the objective lens 400, the adhesive 183, which is an elastic member sandwiched between the multiple members constituting the lens holding frame 480, and the adhesive 481 for fixing the lens L6 are different, so that a lens with a thin edge surface such as the lens L6 can be firmly held while reducing the distortion of the lens caused by the pressing force of the pressing ring 190, thereby achieving high optical performance. More specifically, the elastic modulus of the adhesive 183 is lower than that of the adhesive 481, so that the high flexibility of the adhesive 183 can fully absorb the deformation of the fixed member 181 and suppress the distortion of the lens L6. Furthermore, the adhesive area of the adhesive 183 is wider than that of the adhesive 481, so that the distortion of the lens L6 can be more reliably suppressed. Also, the elastic modulus of the adhesive 481 is higher than that of the adhesive 183, so that the high adhesive force of the adhesive 481 can firmly hold the lens with a thin edge surface.

Fifth embodiment
Fig. 5 is a cross-sectional view of an objective lens 500 according to this embodiment. Fig. 5 shows a cross section of the objective lens 500 on a plane along the optical axis 1. The objective lens 500 shown in Fig. 5 is also an objective lens for a microscope, similar to the objective lens 100 shown in Fig. 1. The objective lens 500 is similar to the objective lens 100, except that the objective lens 500 includes a lens part set 523 instead of the lens part set 123, and includes a lens part set 526 instead of the lens part set 126.

Lens assembly 523 includes lens L13, which is a cemented lens consisting of lens L13a and lens L13b, and lens holding frame 550. Lens holding frame 550 includes adhesive 553, which is an example of an elastic member, and multiple members (fixed member 551, lens holding member 552) that are fixed with adhesive 553 sandwiched between them. Furthermore, lens holding member 552 has a recess 550a that absorbs distortion that occurs in lens holding frame 550.

Lens assembly 526 differs from lens assembly 126 in that it includes a lens holding frame 580 instead of lens holding frame 180. Lens holding frame 580 includes adhesive 583, which is an example of an elastic member, and multiple members (fixed member 581, lens holding member 582) that are fixed with adhesive 583 sandwiched between them. Furthermore, fixed member 581 has a recess 580a that absorbs distortion that occurs in lens holding frame 580.

In both lens holding frame 550 and lens holding frame 580, the elastic member (adhesive 553, adhesive 583) is interposed between multiple members in the radial direction of objective lens 500, but not in the axial direction. In other words, it is interposed only in the radial direction.

Even with the objective lens 500 configured as described above, the elastic member (adhesive 553, adhesive 583) absorbs the deformation of the lens holding member caused by the pressing force of the pressing ring 190, and lens distortion can be suppressed. Therefore, like the objective lens 100, it is possible to achieve both impact resistance and optical performance.

In addition, in the objective lens 500, the lens holding frame (lens holding frame 550, lens holding frame 580) has a recess as well as an elastic member. The portion of the lens holding frame that is thinned by the recess (hereinafter, the thin portion) has the effect of absorbing deformation caused by the pressing force of the pressing ring 190, for example, as described in Patent Document 1. By having both an elastic member and a recess, deformation that cannot be absorbed by one can be absorbed by the other. Specifically, in the lens holding frame 550, the deformation of the fixed member 551 that cannot be absorbed by the adhesive 553 can be absorbed by the recess 550a, thereby suppressing distortion of the lens L13. In addition, in the lens holding frame 580, the deformation of the fixed member 581 that cannot be absorbed by the recess 580a can be absorbed by the adhesive 583, thereby suppressing distortion of the lens L6. Therefore, according to the objective lens 500, it is possible to reliably suppress deterioration of optical performance caused by the pressing force of the pressing ring 190 and maintain high optical performance.

In addition, in the objective lens 500, since the elastic member is interposed only in the radial direction of the multiple members, even if the elastic member expands or contracts due to a temperature change, the lens can be prevented from moving in the optical axis direction. Therefore, in addition to the deterioration of optical performance caused by the pressing force of the pressing ring 190, the objective lens 500 can also suppress the deterioration of optical performance caused by temperature changes, similar to the objective lens 200 and the objective lens 300.

The above-mentioned embodiments are illustrative examples for the purpose of facilitating understanding of the invention, and the present invention is not limited to these embodiments. Modifications of the above-mentioned embodiments and alternatives to the above-mentioned embodiments may be included. In other words, the components of each embodiment can be modified without departing from the spirit and scope of the embodiment. In addition, new embodiments can be implemented by appropriately combining multiple components disclosed in one or more embodiments. In addition, some components may be deleted from the components shown in each embodiment, or some components may be added to the components shown in the embodiment. Furthermore, the processing procedures shown in each embodiment may be performed in a different order as long as there is no contradiction. In other words, the objective lens of the present invention can be modified and changed in various ways without departing from the scope of the claims.

In this specification, the terms "first," "second," and the like, used to modify a noun do not limit the quantity or order of the elements described by the noun. These terms are used to distinguish between two or more elements, not less, not more. Thus, the specification of a "first" and a "second" element does not imply that the "first" element precedes the "second" element, nor does it negate the presence of a "third" element.

1...Optical axis, 100, 200, 300, 400, 500...Objective lens, 110...Objective barrel, 111...Screw engagement portion, 121-126, 223, 226, 326, 426, 523, 526...Lens assembly, 130, 140, 150, 160, 170, 180, 250, 280, 380, 480, 550, 580...Lens holding frame, 181, 251, 281, 381, 551, 581.・・Fixed member, 182, 252, 282, 382, 552, 582...Lens holding member, 183, 384, 385, 481, 553, 583...Adhesive, 190...Press ring, 253...Leaf spring, 283...Elastic rubber ring, 284...Screw, 383...Intermediate member, 550a, 580a...Recess, L1-L6, L3a-L3c, L13, L13a, L13b...Lens

Claims (8)

An objective lens,
An objective lens barrel;
A plurality of lens assembly sets arranged in the objective barrel, each of the plurality of lens assembly sets including at least a lens and a lens holding frame holding the lens;
a pressing member fixed to the objective barrel, the pressing member pressing the lens subassemblies against the objective barrel along an optical axis direction of the objective lens,
At least one of the plurality of lens assembly includes a first lens holding frame including an elastic member and a plurality of members fixed in a state in which the elastic member is sandwiched between the first lens holding frame and the second lens holding frame,
the objective lens further includes a second adhesive that bonds the first lens holding frame and the lens held by the first lens holding frame to each other;
the elastic member is a first adhesive that bonds the plurality of members to each other,
The first adhesive has a lower modulus of elasticity than the second adhesive.
An objective lens characterized by: 2. The objective lens according to claim 1,
An objective lens, characterized in that the elastic member is interposed between the plurality of members in a radial direction of the objective lens. 3. The objective lens according to claim 2,
An objective lens, characterized in that the elastic member is not interposed between the plurality of members in the optical axis direction of the objective lens. The objective lens according to any one of claims 1 to 3,
The objective lens, wherein the elastic member has a lower elastic modulus than the plurality of members. The objective lens according to any one of claims 1 to 4 ,
An objective lens, wherein an adhesion area of the first adhesive is larger than an adhesion area of the second adhesive. The objective lens according to any one of claims 1 to 5 ,
The lens assembly including the first lens holding frame includes:
a lens assembly placed closest to the pressing member among the plurality of lens assemblies,
The objective lens is fixed in a state where it is sandwiched between another lens assembly and the pressing member. The objective lens according to any one of claims 1 to 6 ,
The objective lens according to claim 1, wherein the first lens holding frame further has a recess for absorbing distortion occurring in the first lens holding frame. The objective lens according to any one of claims 1 to 7 ,
An objective lens, wherein at least one of the plurality of members is a member for fixing the lens.

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