Objective lens system

Abstract

This objective lens system comprises: an objective lens body 10; a gel unit 20; an immersion-liquid unit; and a common attachment / detachment mechanism 40. The objective lens body 10 includes: a tip lens 11 disposed closest to the object side; and a lens holding member 12 for holding the tip lens 11. The gel unit 20 includes: a gel 21; and a gel holding member 22 for holding the gel 21. The gel 21 is disposed on the tip surface of the tip lens 11. The immersion-liquid unit includes an immersion liquid holding member for holding, above the tip surface of the tip lens 11, an immersion liquid for liquid immersion observation. The attachment / detachment mechanism 40 enables each of the gel unit 20 and the immersion-liquid unit to be attached to and detached from the objective lens body 10.

Description

Objective lens system

[0001] The disclosure of this specification relates to an objective lens system.

[0002] In microscopic observation, an immersion objective lens uses an immersion liquid with a refractive index higher than that of air to increase the numerical aperture, enabling high-resolution and high-brightness observation. Also, since the refractive index of the immersion liquid in an immersion objective lens is closer to that of the specimen being observed compared to a dry-type objective lens, it is possible to observe the specimen from its surface to the deep part.

[0003] However, it is not easy to hold the immersion liquid at the tip of the objective lens, and there are difficulties in the cleaning effort after the observation and in the observation while switching to a dry-type objective lens.

[0004] As a technique for eliminating such demerits of an immersion objective lens, a technique of using a solid gel instead of an immersion liquid in immersion observation is known (see, for example, Patent Document 1).

[0005] Japanese Patent Application Laid-Open No. 2023-135604

[0006] When a gel is squeezed, its properties as a solid become more apparent than those of a liquid, and the elastic force increases, and it cannot be squeezed beyond a certain level. Therefore, in observation using a gel instead of an immersion liquid in immersion observation (hereinafter, this observation method will be referred to as "gel immersion observation" (Gel Immersion Observation) in the following description), the observation range in the Z direction (optical axis direction) is limited.

[0007] In such a case, for example, a method of removing the gel and performing normal immersion observation using an immersion liquid instead can be considered. However, in this method, when the working distance of the objective lens is long, a large amount of immersion liquid is required, making it difficult to hold the immersion liquid. Also, the immersion liquid may drip outside the objective lens and flow into the objective lens or the microscope body, which may require troublesome cleaning work. In some cases, there is also a risk of damaging the objective lens or the microscope body due to the inflow of the immersion liquid.

[0008] To prevent such problems, for example, the structure of the objective lens's tip frame could be designed specifically for immersion observation, such as one that retains the immersion liquid and prevents it from dripping. However, in this case, the user would need to prepare two types of objective lenses—one for gel immersion observation and one for regular liquid immersion observation—which would be a significant financial burden.

[0009] Based on the circumstances described above, one aspect of the present invention is to provide an objective lens system that allows switching between gel immersion observation and liquid immersion observation using a single objective lens.

[0010] An objective lens system according to one aspect of the present invention comprises: an objective lens body including a tip lens positioned closest to the object and a lens holding member for holding the tip lens; a gel unit including a gel and a gel holding member for holding the gel, wherein the gel is placed on the tip surface of the tip lens; an immersion unit including an immersion liquid holding member for holding an immersion liquid for immersion observation on the tip surface of the tip lens; and a common attachment / detachment mechanism that allows the gel unit and the immersion liquid unit to be attached to and detached from the objective lens body, respectively.

[0011] According to the above embodiment, it becomes possible to provide an objective lens system that allows switching between gel immersion observation and liquid immersion observation with a single objective lens.

[0012] This is a cross-sectional view of an example of an objective lens body according to the first embodiment. This is a top view of an example of an objective lens body according to the first embodiment. This is a cross-sectional view of an example of a gel and a first member according to the first embodiment. This is a top view of an example of a first member according to the first embodiment. This is a cross-sectional view of a modified example of the gel and the first member according to the first embodiment. This is a cross-sectional view of an example of a second member according to the first embodiment. This is a top view of an example of a second member according to the first embodiment. This is a cross-sectional view of an example of an objective lens for gel immersion observation according to the first embodiment. This is a cross-sectional view of an example of an immersion liquid holding member according to the first embodiment. This is a top view of an example of an immersion liquid holding member according to the first embodiment. This is a cross-sectional view of an example of an objective lens for liquid immersion observation according to the first embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens body according to the second embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens for gel immersion observation according to the second embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens for liquid immersion observation according to the second embodiment. This is a cross-sectional view of a modified example of the tip portion of an objective lens body according to the second embodiment. This is a cross-sectional view of an example of a gel and a first member according to the third embodiment. This is a cross-sectional view of an example of a second member according to the third embodiment. This is a cross-sectional view of an example of an immersion liquid holding member according to the third embodiment. This is a cross-sectional view of an example of a second member according to the fourth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens body according to the fifth embodiment. This is a cross-sectional view of an example of a gel unit according to the fifth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens during gel immersion observation according to the fifth embodiment. This is a cross-sectional view of an example of an immersion unit according to the fifth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens during liquid immersion observation according to the fifth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens body according to the sixth embodiment. This is a cross-sectional view of an example of a gel unit according to the sixth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens during gel immersion observation according to the sixth embodiment. This is a cross-sectional view of an example of an immersion unit according to the sixth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens during liquid immersion observation according to the sixth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens body according to the seventh embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens during gel immersion observation according to the seventh embodiment. This is a bottom view of an example of a second member according to the seventh embodiment.This is a cross-sectional view of an example of the tip portion of an objective lens during immersion observation according to the seventh embodiment. This is a bottom view of an example of an immersion unit according to the seventh embodiment. This is a top view of an example of a first member according to the eighth embodiment. This is a cross-sectional view of an example of the tip portion of the objective lens body, gel, and first member according to the eighth embodiment. This is a cross-sectional view of an example of the tip portion of the objective lens body according to the ninth embodiment. This is a cross-sectional view of an example of the tip portion of an objective lens after cleaning the immersion liquid according to the ninth embodiment. This is a diagram showing an example of how immersion liquid remains on the tip portion of the objective lens body according to the ninth embodiment. This is a cross-sectional view of a first example of an immersion unit according to the tenth embodiment. This is a cross-sectional view of a second example of an immersion unit according to the tenth embodiment. This is a cross-sectional view of an example of a gel according to the eleventh embodiment. This is a first numerical example of the shape of the gel according to the eleventh embodiment. This is a second numerical example of the shape of the gel according to the eleventh embodiment. This is a third numerical example of the shape of the gel according to the eleventh embodiment.

[0013] The following describes in detail each embodiment of the objective lens system with reference to the drawings.

[0014] (First Embodiment) In this embodiment, the basic configuration of the objective lens system will be described. The objective lens system comprises an objective lens body 10, a gel unit 20, an immersion unit 30, and a detachable mechanism 40.

[0015] First, the configuration of the objective lens body 10 will be described. Figure 1 is a cross-sectional view of an example of the objective lens body 10 according to this embodiment, and Figure 2 is a top view of an example of the objective lens body 10 according to this embodiment.

[0016] The objective lens body 10 has a cylindrical shape with the optical axis 1 as its central axis, and includes at least a tip lens 11 and a lens holding member 12.

[0017] The front lens 11 is the lens that is positioned furthest towards the object (towards the object being observed) on the optical axis 1 of the objective lens body 10, among the lens group that makes up the objective lens body 10.

[0018] The lens holding member 12 is an annular member and has a first contact surface 12a and a second contact surface 12b on the object side. The first contact surface 12a functions as a positioning surface for the gel unit 20 when the gel unit 20 is attached to the objective lens body 10. The second contact surface 12b functions as a positioning surface for the immersion unit 30 when the immersion unit 30 is attached to the objective lens body 10. In this embodiment, the lens holding member 12 is formed such that the first contact surface 12a and the second contact surface 12b are positioned on the image side (opposite side from the object side in the direction of the optical axis 1) than the tip surface 11a of the tip lens 11. This configuration suppresses the shortening of the working distance of the objective lens body 10 when the gel unit 20 or the immersion unit 30 is attached.

[0019] Furthermore, the outer circumferential surface of the lens holding member 12 according to this embodiment is provided with a male screw structure 41a in the circumferential direction of a circle centered on the optical axis 1. The screw mechanism 41 is formed by the combination of this male screw structure 41a and the female screw structures 41b and 41c, described later, which are provided on the gel unit 20 and the immersion unit 30, respectively. This screw mechanism 41 is an example of a common attachment / detachment mechanism 40 that allows the gel unit 20 and the immersion unit 30 to be attached to and detached from the objective lens body 10.

[0020] Next, the gel unit 20 will be described. The gel unit 20 is used during gel immersion observation and consists of a gel 21 and a gel holding member 22. The gel unit 20 is constructed by placing the gel 21 on the tip surface 11a of the tip lens 11 of the objective lens body 10.

[0021] The gel-holding member 22 according to this embodiment is composed of a first member 22-1 and a second member 22-2. Figure 3 is a cross-sectional view of an example of the gel 21 and the first member 22-1 according to this embodiment, and Figure 4 is a top view of an example of the first member 22-1 according to this embodiment. Figure 5 is a cross-sectional view of a modified example of the gel 21 and the first member 22-1 according to this embodiment. Figure 6 is a cross-sectional view of an example of the second member 22-2 according to this embodiment, and Figure 7 is a top view of an example of the second member 22-2 according to this embodiment.

[0022] Gel 21 is, for example, a silicone material with a consistency of 69. Gel 21 has a shape with a spherical convex surface at the top of a cone, but for convenience, the cross-section is depicted as a semicircle in Figures 3 and 5.

[0023] In Figure 3, the conical base 21a of the gel 21 is the contact surface with the tip surface 11a of the tip lens 11 when the gel unit 20 is attached to the objective lens body 10. As shown in Figure 3, by making the surface shape of the base 21a flat, the base 21a and the tip surface 11a can be brought into close contact without trapping air when the gel unit 20 is attached to the objective lens body 10.

[0024] Furthermore, as shown in Figure 5, the surface shape of the bottom surface 21b, which is the contact surface with the tip surface 11a of the tip lens 11 when the gel unit 20 is attached to the objective lens body 10, may be convex in the image direction. With such a shape, when the gel unit 20 is attached to the objective lens body 10, the gel 21 is compressed around the convex portion, making it difficult for air to enter between the bottom surface 21b and the tip surface 11a of the tip lens 11.

[0025] Further details regarding the conical shape of the gel 21 will be described later. In the following description, we will use a gel 21 having a planar base 21a as shown in Figure 3.

[0026] As shown in Figure 4, the first member 22-1 has an annular shape and a circular opening 22-1a in its center. The first member 22-1 holds the gel 21 at the periphery of the circular bottom surface 21a of the gel 21. When the first member 22-1 is holding the gel 21, the opening 22-1a of the first member 22-1 is covered by the bottom surface 21a of the gel 21. The outer end portion 22-1b of the first member 22-1 contacts the first contact surface 12a of the lens holding member 12 when the gel unit 20 is attached to the objective lens body 10, thereby positioning the gel unit 20 relative to the objective lens body 10.

[0027] The second member 22-2 in this embodiment is a member that constitutes the gel-holding member 22 in combination with the first member 22-1, and as shown in Figures 6 and 7, has an annular shape and a circular opening 22-2a in the center. The second member 22-2 presses and fixes the first member 22-1, which holds the gel 21, to the lens-holding member 12 of the objective lens body 10.

[0028] Furthermore, the outer circumference of the second member 22-2 is bent into an L-shape, and a female screw structure 41b is provided in the circumferential direction on the inside of the outer end portion 22-2b, which is the outer circumference. The female screw structure 41b is a structure that can be fitted with a male screw structure 41a provided on the lens holding member 12 of the objective lens body 10. In other words, by rotating the gel unit 20 from the front end of the objective lens body 10 with the optical axis 1 as the axis of rotation, the male screw structure 41a and the female screw structure 41b, which are the screw mechanism 41, fit together, and the gel unit 20 is attached to the objective lens body 10. At this time of attachment, because the gel holding member 22 is formed by the combination of the first member 22-1 and the second member 22-2, the first member 22-1 is gradually pressed against the objective lens body 10 by the second member 22-2 and fixed in place. Therefore, when the gel unit 20 is attached to the objective lens body 10, the rotation of the gel 21 makes it less likely for the gel 21 to be damaged by the frictional force generated between it and the objective lens body 10.

[0029] Furthermore, the gel unit 20 can be removed from the objective lens body 10 by rotating it in the opposite direction to how it was attached.

[0030] In this way, by using a screw mechanism 41 as the attachment / detachment mechanism 40 between the gel unit 20 and the objective lens body 10, the risk of the gel unit 20 detaching from the objective lens body 10 due to vibrations during observation is reduced.

[0031] Figure 8 is a cross-sectional view showing an example of an objective lens used during gel immersion observation according to this embodiment, and represents the state in which the gel unit 20 is attached to the objective lens body 10.

[0032] As shown in Figure 8, when the gel unit 20 is mounted on the objective lens body 10, the tip lens 11 of the objective lens body 10 is positioned in the opening 22-1a of the first member 22-1 of the gel holding member 22, and its tip surface 11a is in close contact with the gel 21. In this state, the first member 22-1 may be configured such that a gap 50a is created between the tip lens 11 of the objective lens body 10 and the first member 22-1 of the gel unit 20. In other words, the diameter of the opening 22-1a of the first member 22-1 may be larger than the diameter of the tip surface 11a, and the first member 22-1 may be formed so that it does not contact the tip lens 11 when the gel unit 20 is mounted on the objective lens body 10. This prevents vignetting caused by the first member 22-1 when observing the object to be observed. Furthermore, this method prevents a decrease in optical performance caused by the first member 22-1 distorting the tip lens 11 when the gel unit 20 is attached to the objective lens body 10.

[0033] Next, the immersion unit 30 will be described. The immersion unit 30 is used during normal immersion observation and holds the immersion liquid for immersion observation on the tip surface 11a of the tip lens 11 of the objective lens body 10.

[0034] The immersion unit 30 according to this embodiment is configured to include an immersion holding member 31. Figure 9 is a cross-sectional view of an example of the immersion holding member 31 according to this embodiment, and Figure 10 is a top view of an example of the immersion holding member 31 according to this embodiment.

[0035] The immersion liquid holding member 31 has an annular shape and a circular opening 31a in its center. When the immersion liquid unit 30 is attached to the objective lens body 10, the immersion liquid holding member 31 comes into contact with the second contact surface 12b of the lens holding member 12, thereby determining the position of the immersion liquid unit 30 relative to the objective lens body 10. At this time, the tip lens 11 of the objective lens body 10 is positioned in the opening 31a of the immersion liquid holding member 31.

[0036] The outer circumference of the immersion fluid holding member 31 is bent into an L-shape, and a female screw structure 41c is provided on the inside of the outer end portion 31b in the circumferential direction. The female screw structure 41c is designed to fit with a male screw structure 41a provided on the lens holding member 12 of the objective lens body 10. In other words, by rotating the immersion fluid unit 30 from the front end of the objective lens body 10 with the optical axis 1 as the axis of rotation, the male screw structure 41a and the female screw structure 41c, which are the screw mechanism 41, fit together, and the immersion fluid unit 30 is attached to the objective lens body 10. By using the screw mechanism 41 as the attachment / detachment mechanism 40 between the immersion fluid unit 30 and the objective lens body 10 in this way, the risk of the immersion fluid unit 30 falling off the objective lens body 10 due to vibrations during observation is reduced.

[0037] As described above, both the female screw structure 41b of the second member 22-2 in the gel holding member 22 and the female screw structure 41c of the immersion liquid holding member 31 can be fitted with the male screw structure 41a of the lens holding member 12. In other words, the screw mechanism 41 composed of the male screw structure 41a and the female screw structures 41b and 41c is an example of a common attachment / detachment mechanism 40 that allows the gel unit 20 and the immersion liquid unit 30 to be attached to and detached from the objective lens body 10, respectively.

[0038] Figure 11 is a cross-sectional view showing an example of an objective lens used for immersion observation according to this embodiment, and represents the state in which the immersion unit 30 is attached to the objective lens body 10.

[0039] As shown in Figure 11, when the immersion unit 30 is mounted on the objective lens body 10, the immersion holding member 31 is in close contact with the second contact surface 12b of the lens holding member 12, and the tip lens 11 of the objective lens body 10 is positioned in the opening 31a of the immersion holding member 31. At this time, the immersion holding member 31 is formed such that a gap 50b is created between the tip lens 11 of the objective lens body 10 and the immersion holding member 31. In other words, the diameter of the opening 31a of the immersion holding member 31 is formed to be larger than the diameter of the tip surface 11a, and the immersion holding member 31 may be formed so that it does not contact the tip lens 11 when the immersion unit 30 is mounted on the objective lens body 10. This prevents vignetting caused by the immersion holding member 31 when observing the object to be observed. Furthermore, this method prevents a decrease in optical performance caused by the immersion holding member 31 distorting the tip lens 11 when the immersion unit 30 is attached to the objective lens body 10.

[0040] Furthermore, the immersion liquid used for immersion observation is held on the surface of the tip surface 11a of the tip lens 11 by the inner circumferential surface of the immersion liquid holding member 31, which forms an opening 31a, and the second contact surface 12b of the lens holding member 12, thereby suppressing outflow to the outside and inflow into the interior of the objective lens body 10.

[0041] Since each component of the objective lens system according to this embodiment has the configuration described above, it is possible to switch between gel immersion observation and liquid immersion observation using a single objective lens body 10.

[0042] In this embodiment, the objective lens system involves repeated attachment and detachment of the gel unit 20 or immersion unit 30 to the objective lens body 10 during actual use. Therefore, the lens holding member 12 and the gel holding member 22 (first member 22-1) or immersion holding member 31 repeatedly come into contact with each other. Consequently, high durability is desirable for these components. However, consideration of manufacturing costs is also necessary.

[0043] Here, considering that it is difficult to remove and replace the lens holding member 12 from the objective lens body 10, it is preferable that the lens holding member 12 has high durability. On the other hand, the first member 22-1, the second member 22-2, and the immersion liquid holding member 31 can be made into replaceable consumables and do not require the same level of durability as the lens holding member 12.

[0044] Therefore, the first member 22-1 of the gel holding member 22 and the immersion liquid holding member 31 may be made of a polymer material, and the lens holding member 12 may be made of a metal material to achieve a balance between durability and manufacturing cost. As polymer materials with low manufacturing costs, for example, PET (Polyethylene Terephthalate), plastic, etc. can be used. Also, as metal materials with high durability, for example, brass, aluminum, SUS (Steel Use Stainless), etc. can be used.

[0045] In the description of the objective lens system according to other embodiments hereinafter, for the components of the objective lens system according to this embodiment and the components with different features, the description of their features will be given.

[0046] (Second Embodiment) The objective lens system according to this embodiment includes the same components as the first embodiment, but is characterized in the configuration of the lens holding member 12 of the objective lens body 10.

[0047] FIG. 12 is a cross-sectional view of an example of the tip portion of the objective lens body 10 according to this embodiment, showing the tip lens 11 and the lens holding member 12. As can be seen by comparing this FIG. 12 with the lens holding member 12 in FIG. 1, in FIG. 1, the lens holding member 12 has the first contact surface 12a and the second contact surface 12b, while in FIG. 12, the lens holding member 12 has the second contact surface 12b but does not have the first contact surface 12a.

[0048] In the lens holding member 12 according to the first embodiment, the first contact surface 12a functions as the positioning surface of the gel unit 20. On the other hand, in the lens holding member 12 according to the present embodiment, the second contact surface 12b shares the function as the positioning surface of the gel unit 20 and the function as the positioning surface of the immersion liquid unit 30.

[0049] FIG. 13 is a cross-sectional view showing an example of the tip portion of the objective lens during gel immersion observation according to the present embodiment, and represents a state in which the gel unit 20 is attached to the objective lens body 10 according to the present embodiment. In FIG. 13, the first member 22-1 of the gel holding member 22 in the gel unit 20 contacts the second contact surface 12b of the lens holding member 12, thereby determining the position of the gel unit 20 with respect to the objective lens body 10.

[0050] FIG. 14 is a cross-sectional view showing an example of the tip portion of the objective lens during immersion liquid immersion observation according to the present embodiment, and represents a state in which the immersion liquid unit 30 is attached to the objective lens body 10 according to the present embodiment. In FIG. 14, the immersion liquid holding member 31 in the immersion liquid unit 30 contacts the second contact surface 12b of the lens holding member 12, thereby determining the position of the immersion liquid unit 30 with respect to the objective lens body 10.

[0051] As described above, the lens holding member 12 according to the present embodiment is characterized in that it has the second contact surface 12b as a common contact surface for determining the position with respect to the objective lens body 10 during the attachment of each of the gel unit 20 and the immersion liquid unit 30. By doing so, compared with the lens holding member 12 of the first embodiment having both the first contact surface 12a and the second contact surface 12b that require formation with high accuracy while suppressing variations, it is possible to suppress the manufacturing cost of the lens holding member 12.

[0052] Furthermore, as a method for forming the second contact surface 12b, which requires such high precision, on the lens holding member 12, one possible method is to alternately measure the positional relationship between the tip surface 11a of the tip lens 11 and the second contact surface 12b, and then form the second contact surface 12b by cutting. However, in this method, the surface treatment of the lens holding member 12 will be removed. Therefore, surface treatment to prevent corrosion of the lens holding member 12 due to the adhesion of immersion liquid, for example, needs to be applied after the formation of the second contact surface 12b is complete.

[0053] Therefore, the lens holding member 12 may be provided with a configuration that allows for adjustment of the positional relationship between the common contact surfaces that come into contact with the gel unit 20 and the immersion unit 30 during mounting, and the tip surface 11a of the tip lens 11.

[0054] Figure 15 is a cross-sectional view of a modified example of the tip portion of the objective lens body 10 according to this embodiment, and this figure shows the tip lens 11 and the lens holding member 12. In this modified example, the lens holding member 12 is composed of a base member 12-1, a contact surface member 12-2, and an adjustment member 12-3.

[0055] The base member 12-1 is a member that holds the tip lens 11 at the tip of the objective lens body 10.

[0056] The contact surface member 12-2 is a member having a common contact surface 12-2a that contacts the gel holding member 22 when the gel unit 20 is mounted on the objective lens body 10, and contacts the immersion liquid holding member 31 when the immersion liquid unit 30 is mounted on the objective lens body 10.

[0057] The adjustment member 12-3 is a metal, annular member, similar to a flat washer. The adjustment member 12-3 is interposed between the base member 12-1 and the contact surface member 12-2 to determine the positional relationship of the objective lens body 10 in the optical axis direction between the tip surface 11a of the tip lens 11 and the contact surface 12-2a. Therefore, by replacing the adjustment members 12-3 of different thicknesses and interposing them between the base member 12-1 and the contact surface member 12-2, it becomes possible to adjust the positional relationship between the tip surface 11a of the tip lens 11 and the contact surface 12-2a. Furthermore, by configuring the lens holding member 12 in this way, a highly accurate contact surface 12-2a can be obtained without cutting the lens holding member 12, thus not affecting the surface treatment of the lens holding member 12.

[0058] Furthermore, the base member 12-1 is provided with a male screw structure 42a, separate from the male screw structure 41a, in the circumferential direction with respect to the optical axis 1. The outer circumference of the contact surface member 12-2 is bent into an L shape, and a female screw structure 42b, which can be fitted with the male screw structure 42a, is provided in the circumferential direction on the inside of the outer end portion 12-2b, which is the outer circumference. In other words, by interposing the adjustment member 12-3 between the base member 12-1 and the contact surface member 12-2, and rotating the gel unit 20 from the tip side of the objective lens body 10 with respect to the optical axis 1 as the axis of rotation, the male screw structure 42a and the female screw structure 42b, which constitute the screw mechanism 42, are fitted together. In this way, the base member 12-1, the contact surface member 12-2, and the adjustment member 12-3 are integrated to form the lens holding member 12 shown in Figure 15.

[0059] (Third Embodiment) The objective lens system according to this embodiment has the same components as the first embodiment, but is characterized by the thickness of the first member 22-1 and the second member 22-2 that constitute the gel holding member 22 of the gel unit 20 and the immersion liquid holding member 31 that constitutes the immersion liquid unit 30.

[0060] Figure 16 is a cross-sectional view of an example of the gel 21 and the first member 22-1 according to this embodiment, Figure 17 is a cross-sectional view of an example of the second member 22-2 according to this embodiment, and Figure 18 is a cross-sectional view of an example of the immersion-holding member 31 according to this embodiment.

[0061] In this embodiment, the thickness of the gel-holding member 22, that is, the thickness t1 of the first member 22-1, the thickness t2 of the second member 22-2, and the thickness t3 of the immersion liquid-holding member 31, are all 0.4 millimeters or more. Having such thicknesses ensures stable strength for each member, thereby reducing the possibility of errors in attaching or detaching the gel unit 20 or the immersion liquid unit 30 to the objective lens body 10.

[0062] (Fourth Embodiment) As can be seen by comparing Figure 6 and Figure 9, in the objective lens system according to the first embodiment, the second member 22-2 constituting the gel holding member 22 of the gel unit 20 and the immersion liquid holding member 31 of the immersion liquid unit 30 are similar in shape, so there is a possibility of confusing the two. On the other hand, the objective lens system according to this embodiment is characterized in that the second member 22-2 and the immersion liquid holding member 31, which are components of the objective lens system according to the first embodiment, have easily distinguishable features.

[0063] Figure 19 is a cross-sectional view of an example of the second member 22-2 according to this embodiment. The outer circumference of this second member 22-2 is bent in two stages, and has an outer end portion 22-2b which is the first stage bend on the outer circumference side, and a bent portion 22-2c which is the second stage bend closer to the inner circumference than the outer end portion 22-2b. A female screw structure 41b is provided on the inside of the outer end portion 22-2b in the circumferential direction.

[0064] On the other hand, the immersion-holding member 31 according to this embodiment is identical to that of the first embodiment, for example, as shown in Figure 9 for its cross-sectional view. This immersion-holding member 31 has a single-step bending of its outer circumference. A female screw structure 41c is provided in the circumferential direction on the inside of the outer end portion 31b, which is the L-shaped bent outer circumference of the immersion-holding member 31.

[0065] Thus, since the second member 22-2 and the immersion-holding member 31 in this embodiment have clearly different shapes in terms of the number of bends in their outer circumference, they can be easily distinguished both visually and tactilely.

[0066] In addition to the method of making the two components different in shape, various methods can be employed to make the second component 22-2 and the immersion liquid-holding component 31 easily distinguishable.

[0067] For example, the second member 22-2 and the immersion liquid holding member 31 according to the first embodiment, which have similar shapes and whose cross-sectional views are shown in Figures 6 and 9 respectively, may each have an identifier that can distinguish themselves from the other. That is, for example, different letters or symbols may be attached to the second member 22-2 and the immersion liquid holding member 31 as identifiers, so that the gel unit 20 and the immersion liquid unit 30 can be visually distinguished.

[0068] Furthermore, the second member 22-2 and the immersion liquid holding member 31 according to the first embodiment, whose cross-sectional views are shown in Figures 6 and 9 respectively, may be subjected to different surface treatments, making them distinguishable by touch due to the difference in these treatments. For example, knurling may be applied to the outer end portion 22-2b of the second member 22-2 and the outer end portion 31b of the immersion liquid holding member 31, and the direction of the lines forming the knurling and the density of the lines may be made different for the two. This difference in line direction and density can be distinguished by touch. Also, knurling is an example of an anti-slip treatment, and the treated area provides an anti-slip effect. Therefore, by applying knurling to the outer end portion 22-2b of the second member 22-2 and the outer end portion 31b of the immersion liquid holding member 31, the operability of attaching and detaching the gel unit 20 and the immersion liquid unit 30 to the objective lens body 10 is improved.

[0069] In addition, the second member 22-2 and the immersion liquid-holding member 31 in the first embodiment, whose cross-sectional views are shown in Figures 6 and 9 respectively, may be made of different materials, making the difference in materials distinguishable by touch. That is, for example, one of the second member 22-2 and the immersion liquid-holding member 31 may be made of metal and the other of rubber, so that the differences between the two, such as thermal conductivity and surface roughness, can be distinguished by touch.

[0070] (Fifth Embodiment) In the objective lens systems according to the first to fourth embodiments, a screw mechanism 41 is provided as a common attachment / detachment mechanism 40 that allows the gel unit 20 and the immersion unit 30 to be attached to and detached from the objective lens body 10, respectively. In contrast, the objective lens system according to this embodiment is characterized in that it employs a different component from the screw mechanism 41 as the attachment / detachment mechanism 40.

[0071] Figure 20 is a cross-sectional view of an example of the tip portion of the objective lens body 10 according to this embodiment, showing the tip lens 11 and the lens holding member 12. As can be seen by comparing Figure 20 with the lens holding member 12 of Figure 12, the lens holding member 12 according to this embodiment does not have the male screw structure 41a that was provided in the lens holding member 12 according to the second embodiment. In addition, the lens holding member 12 according to this embodiment is the same as the lens holding member 12 according to the second embodiment in that the second contact surface 12b shares the function of being a positioning surface for the gel unit 20 and a positioning surface for the immersion unit 30.

[0072] Figure 21 is a cross-sectional view of an example of the gel unit 20 according to this embodiment. The gel unit 20 according to this embodiment comprises a gel 21, a gel holding member 22, and a bonding member 43.

[0073] The gel 21 according to this embodiment is the same as the gel 21 of the first embodiment shown in the cross-sectional view in Figure 3.

[0074] The gel-holding member 22 according to this embodiment is a member that holds the gel 21 and has the same shape as the first member 22-1 in the first embodiment shown in the cross-sectional view in Figure 3. In this embodiment, the second member 22-2 is unnecessary.

[0075] The connecting member 43 is an example of a detachable mechanism 40 for attaching the gel unit 20 to the objective lens body 10.

[0076] Figure 22 is a cross-sectional view showing an example of the tip portion of the objective lens during gel immersion observation according to this embodiment, and represents the state in which the gel unit 20 is attached to the objective lens body 10 according to this embodiment. The bonding member 43 is positioned on the contact portion of the gel holding member 22 that contacts the second contact surface 12b of the lens holding member 12 when the gel unit 20 is attached to the objective lens body 10.

[0077] In this embodiment, the joining member 43 is an adhesive member that adheres the gel holding member 22 and the lens holding member 12 together by adhesive force. As this adhesive member, for example, a weakly adhesive double-sided tape or spray adhesive can be used, which has adhesive force but can also be peeled off relatively easily.

[0078] Figure 23 is a cross-sectional view of an example of the immersion unit 30 according to this embodiment. The immersion unit 30 according to this embodiment includes an immersion holding member 31 and a joining member 43.

[0079] The immersion-holding member 31 according to this embodiment has the same shape as the immersion-holding member 31 according to the first embodiment, which is shown in a cross-sectional view in Figure 9, but it does not have the female screw structure 41c that was provided in the immersion-holding member 31 according to the first embodiment.

[0080] The joining member 43 is an example of a detachable mechanism 40 for attaching the immersion unit 30 to the objective lens body 10.

[0081] Figure 24 is a cross-sectional view showing an example of the tip portion of the objective lens during immersion observation according to this embodiment, and represents the state in which the immersion unit 30 is attached to the objective lens body 10 according to this embodiment. The bonding member 43 is positioned on the contact portion of the immersion holding member 31 that contacts the second contact surface 12b of the lens holding member 12 when the immersion unit 30 is attached to the objective lens body 10. This bonding member 43 is, for example, the same adhesive member as that provided in the gel unit 20.

[0082] In this way, by using the adhesive bonding member 43 as the attachment / detachment mechanism 40, the risk of the gel unit 20 or immersion unit 30 detaching from the objective lens body 10 due to vibrations during observation or the influence of the object being observed is reduced.

[0083] Furthermore, in this embodiment, a magnet may be used as the joining member 43 to allow the gel unit 20 and the immersion unit 30 to be attached to and detached from the objective lens body 10 by magnetic force. That is, for example, the lens holding member 12 of the objective lens body 10 may be made of a magnetic material, and a magnetic sheet or magnetic tape may be used as the joining member 43 of the gel unit 20 and the immersion unit 30, respectively. Even with such a configuration, the risk of the gel unit 20 or the immersion unit 30 detaching from the objective lens body 10 due to vibrations during observation or the influence of the object being observed is reduced.

[0084] (Sixth Embodiment) The objective lens system according to this embodiment is characterized in that it employs a fitting mechanism 44 as a attachment / detachment mechanism 40 that is different from any of the objective lens systems according to the first to fifth embodiments.

[0085] Figure 25 is a cross-sectional view of an example of the tip portion of the objective lens body 10 according to this embodiment, showing the tip lens 11 and the lens holding member 12. As can be seen by comparing Figure 25 with the lens holding member 12 of Figure 12, the lens holding member 12 according to this embodiment has an annular recess 12c surrounding the tip lens 11 instead of the male screw structure 41a that was provided in the lens holding member 12 according to the second embodiment. The lens holding member 12 according to this embodiment is the same as the lens holding member 12 according to the second embodiment in that the second contact surface 12b shares the function of being a positioning surface for the gel unit 20 and a positioning surface for the immersion unit 30.

[0086] Figure 26 is a cross-sectional view of an example of the gel unit 20 according to this embodiment. The gel unit 20 according to this embodiment is composed of a gel 21 and a gel holding member 22.

[0087] The gel 21 according to this embodiment is the same as the gel 21 of the first embodiment shown in the cross-sectional view in Figure 3.

[0088] The gel-holding member 22 according to this embodiment is an annular member and has an opening 22a in its center, similar to the opening 22-1a of the first member 22-1, which is a component of the gel-holding member 22 according to the first embodiment. The gel-holding member 22 according to this embodiment holds the gel 21 at the periphery of the circular bottom surface 21a of the gel 21.

[0089] Furthermore, the gel-holding member 22 according to this embodiment has an L-shaped bend in its outer circumference, and a protrusion 22c is provided on the inside of the outer end portion 22b, which is the outer circumference. The protrusion 22c is structured to fit into a recess 12c formed in the lens-holding member 12 of the objective lens body 10 according to this embodiment, and the fitting mechanism 44 is formed by the combination of the protrusion 22c and the recess 12c. The gel-holding member 22 according to this embodiment is made of an elastic material such as plastic, and the protrusion 22c is made of a metal material.

[0090] Figure 27 is a cross-sectional view of an example of the tip portion of the objective lens during gel immersion observation according to this embodiment, showing the state in which the gel unit 20 is attached to the objective lens body 10 according to this embodiment.

[0091] To attach the gel unit 20 to the objective lens body 10, the gel unit 20 is pushed into the objective lens body 10 from the front end. The elastic gel retaining member 22 then flexes as it moves, and the protrusion 22c of the gel retaining member 22, which is the fitting mechanism 44, fits into the recess 12c of the lens retaining member 12, thereby attaching the gel unit 20 to the objective lens body 10. To remove the gel unit 20 from the objective lens body 10, the gel unit 20 is pulled up towards the front end of the objective lens body 10.

[0092] Figure 28 is a cross-sectional view of an example of the immersion unit 30 according to this embodiment. The immersion unit 30 according to this embodiment includes an immersion holding member 31 and a joining member 43.

[0093] The immersion-holding member 31 according to this embodiment has a shape similar to the immersion-holding member 31 according to the first embodiment, whose cross-sectional view is shown in Figure 9. However, the female screw structure 41c that was provided in the immersion-holding member 31 according to the first embodiment is not provided. Instead, the immersion-holding member 31 according to this embodiment is provided with a protrusion 31c on the inside of the outer end portion 31b.

[0094] The protrusion 31c is structured to fit into the recess 12c formed in the lens holding member 12 of the objective lens body 10 according to this embodiment, and the combination of the protrusion 31c and the recess 12c constitutes a fitting mechanism 44. In other words, the fitting mechanism 44, which consists of the protrusions 22c and 31c and the recess 12c, is an example of a common attachment / detachment mechanism 40 that allows the gel unit 20 and the immersion unit 30 to be attached to and detached from the objective lens body 10, respectively. The immersion holding member 31 according to this embodiment is made of an elastic material such as plastic, and the protrusion 31c is made of a metal material.

[0095] Figure 29 is a cross-sectional view of an example of the tip portion of the objective lens during immersion observation according to this embodiment, showing the state in which the immersion unit 30 is attached to the objective lens body 10 according to this embodiment.

[0096] The method for attaching the immersion unit 30 to the objective lens body 10 is the same as in the case of the gel unit 20. That is, the immersion unit 30 is pushed into the objective lens body 10 from the front end. As a result, the elastic immersion holding member 31 flexes and moves forward, and the convex portion 31c of the immersion holding member 31, which is the fitting mechanism 44, fits into the concave portion 12c of the lens holding member 12, thereby attaching the immersion unit 30 to the objective lens body 10. To remove the immersion unit 30 from the objective lens body 10, the immersion unit 30 is pulled up towards the front end of the objective lens body 10.

[0097] As described above, in the objective lens system according to this embodiment, a fitting mechanism 44 is provided as a common attachment / detachment mechanism 40, and the gel unit 20 and the immersion unit 30 are attached to the objective lens body 10 using elastic force, so that attachment and detachment can be easily performed.

[0098] In this embodiment, the protrusions 22c of the gel-holding member 22 and 31c of the immersion-holding member 31 may be made of elastically deformable materials. An example of an elastically deformable material that can be used as the protrusions 22c and 31c is rubber. In this case, when the gel unit 20 or the immersion-holding unit 30 is pushed into the objective lens body 10 from the front end, the protrusions 22c and 31c themselves will bend and then fit into the recess 12c of the lens-holding member 12. Therefore, even if the gel-holding member 22 and the immersion-holding member 31 are not elastic, the gel unit 20 and the immersion-holding unit 30 can be easily attached to the objective lens body 10.

[0099] Incidentally, the immersion-holding member 31, whose cross-sectional view is shown in Figure 28, is provided with a flexible member 31d on the inner surface of the opening 31a. The flexible member 31d is, for example, a rubber material.

[0100] When the immersion unit 30 is attached to the objective lens body 10, the flexible member 31d comes into contact with the tip lens 11. As can be seen from the cross-sectional view in Figure 29, when the immersion unit 30 is attached to the objective lens body 10, the flexible member 31d is interposed between it and the tip lens 11.

[0101] By providing the immersion liquid holding member 31 with such a flexible member 31d, the distortion transmitted to the tip lens 11 when the immersion liquid unit 30 is attached to the objective lens body 10 is mitigated, thereby suppressing a decrease in the optical performance of the objective lens body 10 caused by the attachment operation. In addition, when the gap between the flexible member 31d and the tip lens 11 is filled by the flexible member 31d, the contact area between the immersion liquid and the tip lens 11 is reduced, thus reducing the burden of cleaning work to remove the immersion liquid.

[0102] Furthermore, the immersion-holding member 31 according to other embodiments may also be provided with a flexible member 31d. That is, for example, the immersion-holding member 31 according to the first embodiment may be provided with a flexible member 31d on the inner surface of the opening 31a, so that when the immersion unit 30 is attached to the objective lens body 10, the flexible member 31d fills the gap 50b shown in the cross-sectional view of Figure 11.

[0103] (Seventh Embodiment) The objective lens system according to this embodiment is characterized in that it uses a bayonet coupling as the attachment / detachment mechanism 40, which is different from any of the objective lens systems according to the first to sixth embodiments.

[0104] Figure 30 is a cross-sectional view of an example of the tip portion of the objective lens body 10 according to this embodiment, showing the tip lens 11 and the lens holding member 12. Figure 31 is a cross-sectional view of an example of the tip portion of the objective lens during gel immersion observation according to this embodiment, showing the state in which the gel unit 20 is attached to the objective lens body 10 according to this embodiment. Figure 32 is a bottom view of an example of the second member 22-2 according to this embodiment.

[0105] The lens holding member 12 according to this embodiment, like the lens holding member 12 according to the second embodiment shown in the cross-sectional view in Figure 12, has a second contact surface 12b that shares the function of a positioning surface for the gel unit 20 and a positioning surface for the immersion unit 30. Furthermore, the lens holding member 12 according to this embodiment is provided with three engaging elements 45a on the outer circumference of its annular shape. As shown in Figure 30, the engaging elements 45a have a shape corresponding to a part of a ring. Also, as shown in Figure 31, a leaf spring 45b is provided on the lower side (image side in the objective lens body 10) of each engaging element 45a.

[0106] On the other hand, the gel unit 20 according to this embodiment is composed of a gel 21 and a gel holding member 22, and the gel holding member 22 is composed of a first member 22-1 and a second member 22-2. Of these, the gel 21 and the first member 22-1 are the same as those in the first embodiment shown in Figure 3.

[0107] In this embodiment, the second member 22-2 has an L-shaped bend in its outer circumference, and the outer end portion 22-2b is provided with three engaging elements 45c having the same shape as the engaging element 45a provided on the lens holding member 12.

[0108] In this embodiment, the bayonet coupling mechanism 45 is formed by the combination of the engaging element 45a and leaf spring 45b of the lens holding member 12 and the engaging element 45c of the second member 22-2. Specifically, with the first member 22-1 positioned at the front end of the objective lens body 10, the second member 22-2 is placed over the objective lens body 10 from the front end, and the engaging element 45c of the second member 22-2 is fitted between the engaging elements 45a of the lens holding member 12. When the second member 22-2 is rotated around the optical axis 1 of the objective lens body 10 as the axis of rotation, the leaf spring 45b is positioned between the engaging elements 45a and 45c. At this time, the elastic force of the leaf spring 45b acts in a direction that widens the gap between the engaging elements 45a and 45c, resulting in the gel unit 20 being attached to the objective lens body 10.

[0109] Furthermore, by rotating the gel unit 20 and positioning the engaging element 45c of the second member 22-2 between the engaging elements 45a of the lens holding member 12, the gel unit 20 can be removed from the objective lens body 10.

[0110] Figure 33 is a cross-sectional view of an example of the tip portion of the objective lens during immersion observation according to this embodiment, showing the state in which the immersion unit 30 is attached to the objective lens body 10 according to this embodiment. Figure 34 is a bottom view of an example of the immersion unit 30 according to this embodiment.

[0111] The immersion unit 30 according to this embodiment is configured to include an immersion holding member 31.

[0112] In this embodiment, the immersion-holding member 31 has an L-shaped bend in its outer circumference, and the outer end portion 31b of this outer circumference is provided with three engaging elements 45d having the same shape as the engaging element 45a of the lens-holding member 12, similar to the outer end portion 22-2b of the second member 22-2.

[0113] In this embodiment, the bayonet coupling mechanism 45 is formed by the combination of the engaging element 45a and leaf spring 45b of the lens holding member 12 and the engaging element 45d of the immersion liquid holding member 31. Specifically, the immersion liquid holding member 31 is placed over the objective lens body 10 from the front end, and the engaging element 45d of the immersion liquid holding member 31 is fitted between the engaging elements 45a of the lens holding member 12. When the immersion liquid holding member 31 is rotated with the optical axis 1 of the objective lens body 10 as the axis of rotation, the leaf spring 45b is positioned between the engaging elements 45a and 45d. At this time, the elastic force of the leaf spring 45b acts in a direction that widens the gap between the engaging elements 45a and 45d, resulting in the immersion liquid unit 30 being attached to the objective lens body 10.

[0114] Furthermore, by rotating the immersion unit 30 and positioning the engaging element 45d of the immersion holding member 31 between the engaging elements 45a of the lens holding member 12, the immersion unit 30 can be removed from the objective lens body 10.

[0115] As described above, the bayonet coupling mechanism 45, which consists of engaging elements 45a, 45c, and 45d and a leaf spring 45b, is an example of a common attachment / detachment mechanism 40 that allows the gel unit 20 and the immersion unit 30 to be attached to and detached from the objective lens body 10, respectively. In this embodiment, the objective lens system is equipped with a bayonet coupling mechanism 45 as a common attachment / detachment mechanism 40 to attach the gel unit 20 and the immersion unit 30 to the objective lens body 10, making attachment and detachment easy.

[0116] (Eighth Embodiment) The objective lens system according to this embodiment has the same components as the first embodiment, but is characterized by the configuration of the first member 22-1 that constitutes the gel holding member 22 of the gel unit 20.

[0117] Figure 35 is a top view of an example of the first member 22-1 according to this embodiment. The first member 22-1 according to this embodiment has an annular shape and a circular opening 22-1a in the center, and is similar to the first member 22-1 according to the first embodiment in that it holds the gel 21 with the periphery of the circular bottom surface 21a of the gel 21. However, as can be seen by comparing Figure 35 with the first member 22-1 according to the first embodiment shown in Figure 4, the first member 22-1 according to this embodiment is provided with ventilation holes 22-1d. Although two ventilation holes 22-1d are provided in the first member 22-1 in Figure 35, the number of ventilation holes 22-1d provided in the first member 22-1 does not have to be two.

[0118] Figure 36 is a cross-sectional view of an example of the tip portion of the objective lens body 10, the gel 21, and the first member 22-1 according to this embodiment, showing the state in which the gel 21 held by the first member 22-1 is placed on the tip surface 11a of the tip lens 11 of the objective lens body 10.

[0119] When the gel 21 is placed on the tip surface 11a of the tip lens 11, air may remain between the gel 21 and the tip surface 11a. If the gel unit 20 is attached to the objective lens body 10 and gel immersion observation is performed with this air remaining, not only will the desired optical performance not be achieved due to the influence of the remaining air, but damage such as holes may occur in the gel 21. In contrast, the first member 22-1 in this embodiment is provided with a ventilation hole 22-1d, so that the air between the gel 21 and the tip lens 11 is discharged and does not remain. Therefore, good gel immersion observation becomes possible, and damage to the gel 21 is also prevented.

[0120] Note that the attachment / detachment mechanism 40 is not shown in Figure 36. The attachment / detachment mechanism 40 in this embodiment may be a screw mechanism 41 similar to that in the first embodiment. Alternatively, the attachment / detachment mechanism 40 may be configured using a joining member 43 or a fitting mechanism 44, with the first member 22-1 in this embodiment used as the gel holding member 22 in the fifth or sixth embodiment. Alternatively, the attachment / detachment mechanism 40 in this embodiment may be configured using a bayonet coupling mechanism 45 similar to that in the seventh embodiment.

[0121] (Ninth Embodiment) The objective lens system according to this embodiment has the same components as the second embodiment, but is characterized by the configuration of the second contact surface 12b of the lens holding member 12 of the objective lens body 10.

[0122] Figure 37 is a cross-sectional view of an example of the tip portion of the objective lens body 10 according to this embodiment, showing the tip lens 11 and the lens holding member 12. The lens holding member 12 according to this embodiment is characterized in that the second contact surface 12b, which functions as a positioning surface for the immersion unit 30 when the immersion unit 30 is attached, is formed as a plane perpendicular to the optical axis 1 of the objective lens body 10.

[0123] Figure 38 is a cross-sectional view of an example of the tip portion of the objective lens after cleaning the immersion liquid 60 according to this embodiment. Figure 38 shows the state after cleaning has been performed with the immersion liquid holding member 31, which is the immersion liquid unit 30, attached to the objective lens body 10 after immersion observation, and the immersion liquid 60 remains in the gap 50b between the tip lens 11 and the immersion liquid holding member 31. At this time, the second contact surface 12b of the immersion liquid holding member 31 is the surface that the immersion liquid 60 contacts when the immersion liquid unit 30 is attached to the objective lens body 10.

[0124] Figure 39 shows an example of how the immersion liquid 60 remains at the tip of the objective lens body 10, and represents the state after the immersion liquid retaining member 31 has been removed from the objective lens body 10 in the state shown in Figure 38. When the immersion liquid retaining member 31 is removed from the objective lens body 10, the immersion liquid 60 that remained in the gap 50b flows on the second contact surface 12b of the lens retaining member 12 in the direction from the optical axis 1 of the objective lens body 10 toward the outer circumference.

[0125] Here, for example, if the second contact surface 12b is inclined downward from the optical axis 1 of the objective lens body 10 toward the outer circumference, the immersion liquid 60 will not remain on the second contact surface 12b, but will flow out to other parts of the lens holding member 12. The cleaning process to remove such immersion liquid 60 from the objective lens body 10 is complicated.

[0126] Furthermore, for example, if the second contact surface 12b is inclined upward from the optical axis 1 of the objective lens body 10 toward the outer circumference, the outflow of the immersion liquid 60 to other parts of the lens holding member 12 is suppressed. However, in this case, cleaning to remove the immersion liquid 60 remaining in the narrow gap between the tip lens 11 and the second contact surface 12b of the lens holding member 12 is not easy.

[0127] In contrast, in the lens holding member 12 according to this embodiment, the second contact surface 12b is perpendicular to the optical axis 1 of the objective lens body 10. In this case, although the immersion liquid 60 flows from the optical axis 1 of the objective lens body 10 toward the outer circumference, it tends to remain on the second contact surface 12b. Furthermore, with such a second contact surface 12b, cleaning work to remove the immersion liquid 60 remaining on the second contact surface 12b is easy.

[0128] As described above, the lens holding member 12 according to this embodiment has a second contact surface 12b that is perpendicular to the optical axis 1 of the objective lens body 10, which makes cleaning work to remove the immersion liquid 60 easier.

[0129] In the lens holding member 12 according to the first embodiment, there is a first contact surface 12a that functions as a positioning surface for the gel unit 20 and a second contact surface 12b that functions as a positioning surface for the immersion unit 30. In this lens holding member 12 according to the first embodiment, the second contact surface 12b may also be a plane perpendicular to the optical axis 1 of the objective lens body 10, thereby facilitating the cleaning work to remove the immersion liquid 60.

[0130] Furthermore, the lens holding member 12 according to this embodiment is provided with a screw mechanism 41 (male screw structure 41a) similar to that of the first embodiment as the attachment / detachment mechanism 40. Alternatively, in the lens holding member 12 according to other embodiments in which a different mechanism is used as the attachment / detachment mechanism 40, the second contact surface 12b may be a plane perpendicular to the optical axis 1 of the objective lens body 10. This makes the cleaning work to remove the immersion liquid 60 easier.

[0131] (Tenth Embodiment) The objective lens system according to this embodiment has the same components as the first embodiment, but is characterized by the configuration of the immersion liquid holding member 31, which is the immersion liquid unit 30.

[0132] Figure 40 is a cross-sectional view of a first example of the immersion liquid holding member 31 according to this embodiment. As can be seen by comparing Figure 40 with the immersion liquid holding member 31 in Figure 9, the immersion liquid holding member 31 according to this embodiment has a recessed portion 31e on the object-side surface when the immersion liquid unit 30 is mounted on the objective lens body 10. The recessed portion 31e functions as a receiving portion for the immersion liquid 60 used for immersion observation. Therefore, by having a recessed portion 31e in the immersion liquid holding member 31, it is possible to catch any dripping of the immersion liquid 60 during observation and prevent it from flowing out to the outside.

[0133] Figure 41 is a cross-sectional view of a second example of the immersion liquid retaining member 31 according to this embodiment. As can be seen by comparing Figure 40 with the first example in Figure 40, the second example of the immersion liquid retaining member 31 has a recessed portion 31f similar to that of the first example, but the area around the bottom surface of the recessed portion 31f is formed in a curved shape. By making the recessed portion 31f of the immersion liquid retaining member 31 in this shape, cleaning work to remove the immersion liquid 60 from the recessed portion 31f becomes easier.

[0134] Furthermore, the objective lens system may be provided with multiple immersion units 30, each composed of an immersion liquid holding member 31 according to this embodiment or an immersion liquid holding member 31 according to the embodiments described above. That is, the objective lens system may be provided with multiple immersion liquid units 30, and each of these multiple immersion liquid units 30 may have an immersion liquid holding member 31 that has been subjected to a surface treatment having different properties with respect to the immersion liquid 60.

[0135] Examples of surface treatments for the immersion-holding member 31 include hydrophobic coating, chemical-resistant coating, and abrasion-resistant coating. By providing an objective lens system equipped with multiple immersion units 30, each composed of a immersion-holding member 31 with a different surface treatment, various users in different operating environments can select the appropriate immersion unit 30 according to their specific environment.

[0136] For hydrophobic coatings, for example, silicone-based, fluorine-based, or polymer-based compound coatings can be used. On the other hand, for chemical-resistant coatings, for example, ceramic coatings can be used. Furthermore, for abrasion-resistant coatings, ultra-durable organic-inorganic composite coatings can be used.

[0137] (Eleventh Embodiment) The objective lens system according to this embodiment has the same components as the first embodiment, but is characterized by the shape of the gel 21.

[0138] Figure 42 is a cross-sectional view of an example of the gel 21 according to this embodiment. As described in the description of the first embodiment, the gel 21 has a shape in which the apex of the cone is a spherical convex surface. With the gel 21 having such a shape, the initial contact between the gel 21 and the specimen (observation container) is at a single point, and thereafter, as the gel 21 is compressed, the gel 21 and the specimen adhere to each other in a concentric manner from that single point of contact. Therefore, the gel 21 can adhere to the specimen without trapping air in between.

[0139] In Figure 42, H is the height of the gel 21. That is, H is the distance between the base surface 21a of the gel 21, which corresponds to the base of the cone in the shape of the gel 21 described above, and the apex of the gel 21, i.e., the apex of the spherical convex surface which is the top of the cone in the shape of the gel 21 described above. WD is the working distance of the objective lens body 10 to which the gel unit 20 containing the gel 21 is mounted. Also, Φ is the diameter of the base surface 21a of the gel 21, and ΦD is the diameter of the circle which is the cross-section of the gel 21 and is parallel to the base surface 21a and is at a distance from the base surface 21a equal to the working distance WD. And R is the radius of curvature of the apex of the spherical convex surface of the gel 21.

[0140] In this embodiment, it is desirable that the height H of the gel 21 be greater than or equal to the working distance WD of the objective lens body 10. That is, it is desirable that the value of H / WD, which is the ratio of the height H of the gel 21 to the working distance WD of the objective lens body 10 to which the gel unit 20 containing the gel 21 is attached, be 1 or greater. By using a gel 21 having such a height H, it is possible to fill the entire working distance WD of the objective lens body 10 with the gel 21. Therefore, it is possible to perform gel immersion observation with appropriate focus on the object to be observed.

[0141] Furthermore, if the H / WD value exceeds 1.5, the height H of the gel 21 becomes greater than the working distance WD of the objective lens body 10. This results in excessive elastic force causing the gel 21, which has been compressed for focusing during gel immersion observation, to return to its original shape. This elastic force can distort and, in some cases, damage the observation container holding the object to be observed. For this reason, it is preferable that the H / WD value be 1.5 or less.

[0142] Furthermore, in this embodiment, it is desirable that the diameter ΦD of the gel 21, that is, the diameter ΦD of the cross section parallel to the bottom surface 21a and at a distance from the bottom surface 21a equal to the working distance WD of the objective lens body 10, be greater than or equal to the actual field of view (FOV) of the objective lens body 10. In other words, if the actual field of view of the objective lens body 10 is defined as the FOV, it is desirable that the value of ΦD / FOV, which is the ratio of the diameter ΦD of the cross section in the gel 21 to the actual field of view (FOV) of the objective lens body 10, be 1 or greater. By using a gel 21 having such a cross section diameter ΦD, it is possible to fill the entire actual field of view (FOV) of the objective lens body 10 with the gel 21. Therefore, observation can be performed over the entire actual field of view (FOV) of the objective lens body 10.

[0143] Furthermore, if the value of ΦD / FOV exceeds 4, the ΦD value of the gel 21 becomes larger than the actual field of view (FOV) of the objective lens body 10, resulting in an excessively large area of ​​the gel 21 in close contact with the observation container containing the object to be observed. When this area becomes large, air may enter between the observation container and the gel 21 during XY movement of the observation container, that is, when the observation container is moved in a direction perpendicular to the optical axis 1 of the objective lens body 10, and may appear in the observed image. For this reason, it is preferable that the value of ΦD / FOV be 4 or less.

[0144] The following are specific examples of gels 21 that satisfy the above-mentioned conditions H and ΦD. Here, these gels 21 are intended to be used in an objective lens body 10 with a magnification of 25X, NA: 0.85, WD: 2 mm (millimeters), effective diameter of the lens tip: Φ4.2 mm, lens diameter: Φ4.84 mm, and FOV: 1.06 mm.

[0145] Figures 43, 44, and 45 are the first, second, and third numerical examples of the shape of the gel 21 according to this embodiment, respectively. The units of the numerical values ​​shown in each of these figures are all millimeters (mm).

[0146] In the first numerical example shown in Figure 43, H / WD = 2.15 / 2 = 1.075 and ΦD / FOV = 1.06 / 1.06 = 1.

[0147] In the second numerical example shown in Figure 44, H / WD = 2.5 / 2 = 1.25 and ΦD / FOV = 3.19 / 1.06 = 3.

[0148] In the third numerical example shown in Figure 45, H / WD = 3 / 2 = 1.5 and ΦD / FOV = 4.24 / 1.06 = 4.

[0149] As described above, the numerical examples shown in Figures 43, 44, and 45 all satisfy all the aforementioned conditions regarding the H / WD value and the ΦD / FOV value. Therefore, in gel immersion observation performed using a gel 21 having the shape shown in these numerical examples, it is possible to perform gel immersion observation with appropriate focus on the object to be observed, and observation can be performed across the entire actual field of view (FOV) of the objective lens body 10. In addition, the risk of damage to the observation container due to the elastic force of the gel 21 is low, and the possibility of air entering between the observation container and the gel 21 and appearing in the observed image when the observation container moves in the XY direction is reduced.

[0150] The embodiments described above are specific examples provided to facilitate understanding of the invention, and the present invention is not limited to these embodiments. Modified forms of the embodiments described above and alternative forms that replace the embodiments described above may be included. In other words, each embodiment can be modified in terms of its components without departing from its spirit and scope. Furthermore, 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 an embodiment. Moreover, the processing steps shown in each embodiment may be performed in a different order, as long as they do not contradict each other. That is, the objective lens system of the present invention can be modified in various ways without departing from the scope of the claims.

[0151] In this specification, the expression "based on A" does not mean "based solely on A," but rather "based on at least A," and further, "based at least partially on A." That is, "based on A" may also mean based on B in addition to A, or based on a part of A.

[0152] This application is based on Japanese Patent Application No. 2024-161567, filed on September 19, 2024. All of its contents are included herein.

[0153] 1 Optical axis 10 Objective lens body 11 Front lens 11a Front surface 12 Lens holding member 12a First contact surface 12b Second contact surface 12c Recess 12-1 Base member 12-2 Contact surface member 12-2a Contact surface 12-2b Outer end 12-3 Adjustment member 20 Gel unit 21 Gel 21a, 21b Bottom surface 22 Gel holding member 22a Opening 22b Outer end 22c Protrusion 22-1 First member 22-1a Opening 22-1b Outer end 22-1c Inner ring 22-1d Ventilation hole 22-2 Second member 22-2a Opening 22-2b Outer end 30 Immersion unit 31 Immersion holding member 31a Opening 31b Outer end 31c Protrusion 31d Flexible member 31e, 31f Recessed portion 40 Detachable mechanism 41, 42 Screw mechanism 41a, 42a Male screw structure 41b, 41c, 42b Female screw structure 43 Joining member 44 Fitting mechanism 45 Bayonet coupling mechanism 45a, 45c, 45d Engaging element 45b Leaf spring 50a, 50b Gap

Claims

1. An objective lens system characterized by comprising: an objective lens body including a tip lens positioned closest to the object and a lens holding member for holding the tip lens; a gel unit including a gel and a gel holding member for holding the gel, with the gel placed on the tip surface of the tip lens; an immersion unit including an immersion liquid holding member for holding an immersion liquid for immersion observation on the tip surface of the tip lens; and a common attachment / detachment mechanism that allows each of the gel unit and the immersion liquid unit to be attached to and detached from the objective lens body.

2. The objective lens system according to claim 1, characterized in that the gel holding member has an opening in which the tip lens is positioned when the gel unit is mounted on the objective lens body, the immersion liquid holding member has an opening in which the tip lens is positioned when the immersion liquid unit is mounted on the objective lens body, and both the diameter of the opening of the gel holding member and the diameter of the opening of the immersion liquid holding member are larger than the diameter of the tip surface of the tip lens.

3. The objective lens system according to claim 1, wherein the lens holding member has a first contact surface that determines the position of the gel unit relative to the objective lens body by contact with the gel holding member, and a second contact surface that determines the position of the immersion unit relative to the objective lens body by contact with the immersion liquid holding member, and both the first contact surface and the second contact surface are positioned on the image side of the tip surface of the tip lens.

4. The objective lens system according to claim 1, characterized in that the tip surface of the tip lens is flat, and the surface shape of the contact surface of the gel that contacts the tip surface of the tip lens when the gel unit is mounted on the objective lens body is flat or convex in the image direction.

5. The objective lens system according to claim 1, characterized in that the gel holding member is not in contact with the tip lens when the gel unit is mounted on the objective lens body, and the immersion liquid holding member is not in contact with the tip lens when the immersion liquid unit is mounted on the objective lens body.

6. The objective lens system according to claim 1, characterized in that the gel holding member comprises a flexible member interposed between the gel unit and the tip lens when the gel unit is mounted on the objective lens body, and the immersion liquid holding member comprises a flexible member interposed between the immersion liquid unit and the tip lens when the immersion liquid unit is mounted on the objective lens body.

7. The objective lens system according to claim 1, characterized in that the lens holding member has a common contact surface that determines the position of the gel unit relative to the objective lens body by contact with the gel holding member when the gel unit is mounted on the objective lens body, and determines the position of the immersion unit relative to the objective lens body by contact with the immersion holding member when the immersion unit is mounted on the objective lens body.

8. The objective lens system according to claim 1, characterized in that the gel-holding member and the immersion liquid-holding member are made of polymer material, and the lens-holding member is made of metal material.

9. The objective lens system according to claim 1, characterized in that both the gel-holding member and the immersion liquid-holding member have a minimum thickness of 0.4 millimeters or more.

10. The objective lens system according to claim 1, characterized in that the gel-holding member and the immersion liquid-holding member have portions on their surfaces that are treated with an anti-slip finish.

11. The objective lens system according to claim 1, wherein the lens holding member comprises: a base member for holding the tip lens; a contact surface member having a common contact surface that contacts the gel holding member when the gel unit is mounted on the objective lens body and contacts the immersion liquid holding member when the immersion liquid unit is mounted on the objective lens body; and an adjustment member interposed between the base member and the contact surface member to determine the positional relationship of the objective lens body in the optical axis direction between the tip surface of the tip lens of the objective lens body and the contact surface.

12. The objective lens system according to claim 1, characterized in that each of the gel unit and the immersion unit has an identifier that can distinguish itself from the other.

13. The objective lens system according to claim 1, characterized in that the attachment / detachment mechanism is a screw mechanism comprising a male screw structure formed on the lens holding member and female screw structures formed on the gel holding member and the immersion liquid holding member, respectively.

14. The objective lens system according to claim 1, characterized in that the attachment / detachment mechanism is an adhesive member that adheres the gel-holding member or the immersion liquid-holding member to the lens-holding member by adhesive force.

15. The objective lens system according to claim 1, characterized in that the attachment / detachment mechanism is a magnet that uses magnetic force to attach the gel holding member or the immersion liquid holding member to the lens holding member.

16. The objective lens system according to claim 1, characterized in that the gel-holding member and the immersion liquid-holding member are elastic, and the attachment / detachment mechanism is a fitting mechanism consisting of a convex portion and a concave portion, provided on each of the gel-holding member and the immersion liquid-holding member and the lens-holding member.

17. The objective lens system according to claim 1, characterized in that the attachment / detachment mechanism is a fitting mechanism comprising elastically deformable protrusions on the gel-holding member and the immersion liquid-holding member, respectively, and recesses on the lens-holding member.

18. The objective lens system according to claim 1, characterized in that the attachment / detachment mechanism is a bayonet coupling mechanism comprising an engaging element of the gel-holding member and the immersion liquid-holding member, respectively, and an engaging element of the lens-holding member.

19. The objective lens system according to claim 1, wherein the gel-holding member comprises at least a first member for holding the gel and a second member for fixing the first member to the lens-holding member, and the attachment / detachment mechanism is a screw structure comprising a male screw formed on either the second member or the lens-holding member and a female screw formed on the other.

20. The objective lens system according to claim 1, characterized in that the gel-holding member has a vent for discharging air between the gel and the tip lens when the gel is placed on the tip surface of the tip lens in the objective lens body.

21. The objective lens system according to claim 1, characterized in that the lens holding member has a contact surface that comes into contact with the immersion liquid when the immersion unit is mounted on the objective lens body, and the contact surface is perpendicular to the optical axis of the objective lens body.

22. The objective lens system according to claim 1, characterized in that the immersion liquid holding member has a recessed portion on the object-side surface when the immersion liquid unit is mounted on the objective lens body.

23. The objective lens system according to claim 1, characterized in that it comprises a plurality of immersion units, each of which has an immersion holding member that is subjected to a surface treatment having different properties with respect to the immersion liquid.

24. The objective lens system according to claim 1, characterized in that the gel has a shape in which the apex of the cone is a spherical convex surface, and when the distance between the base of the cone and the apex of the convex surface in the shape is H, and the working distance of the objective lens body is WD, the value of H / WD is 1 or more.

25. The objective lens system according to claim 1, characterized in that the gel has a shape in which the apex of the cone is a spherical convex surface, and when the diameter of the circle which is the cross-section of the gel is parallel to the base surface of the cone in the shape and the distance from the base surface is equal to the working distance of the objective lens body is ΦD, and the actual field of view of the objective lens body is FOV, the value of ΦD / FOV is 1 or more.

26. The objective lens system according to 24, characterized in that the gel has an H / WD value of 1 or more and 1.5 or less.

27. The objective lens system according to claim 25, characterized in that the gel has a ΦD / FOV value of 1 or more and 4 or less.

28. The objective lens system according to claim 1, characterized in that the gel has a shape in which the apex of the cone is a spherical convex surface.

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