JP2008111981A - Objective lens with correction collar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens with a correction collar in which an amount of rotative force of the correction collar and a load on the correction collar, etc. can be set to appropriate values, the influence of a load and a deflection caused by a coil spring in the direction crossing the optical axis is minimized or eliminated, and a correction lens group is moved along the optical axis without decentering it. <P>SOLUTION: The objective lens with a correction collar in which a correction lens group 2a is moved in the direction along the optical axis in response to the rotation of the correction collar 7, is provided with coil springs 8a and 8b that press a correction lens group mirror frame 3a for holding the correction lens group 2a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is an objective lens used in, for example, a microscope, and a correction ring having an aberration correction function for correcting aberrations caused by an observation environment such as a refractive index variation due to a thickness of a cover glass or a temperature change. The present invention relates to an attached objective lens.

  For example, an objective lens for a biological microscope having a high NA (aperture ratio) is configured as a means for correcting aberrations caused by an observation environment such as a refractive index change due to a thickness of a cover glass or a temperature change. A function of moving an arbitrary aberration correction lens group (hereinafter referred to as a correction lens group) in the direction along the optical axis is provided. A microscope having such an objective lens with a correction ring is described in Patent Document 1.

  In such an objective lens, as a method of moving the correction lens group, a screw provided on a correction lens group frame holding the correction lens group is pressed against a cam provided on the correction ring, and the correction ring is rotated. There are a method of utilizing the action of the cam generated at the time, a method of providing a cam member that moves in conjunction with the rotation of the correction ring, and utilizing the action of the cam member. Among them, Patent Document 2 discloses an objective lens with a correction ring having a configuration in which a screw provided on a correction lens group lens frame is pressed against a cam provided on a correction ring.

JP 2002-167101 A JP-A-11-248995

  The objective lens with a correction ring that is generally used at present as described above has an objective at the time of speculum if the force required to rotate the correction ring (hereinafter referred to as the amount of rotational force of the correction ring) is too small. Since the correction ring rotates and is out of focus due to minute vibrations or shocks applied to the lens, it is necessary to focus again and again. On the other hand, if the amount of rotational force of the correction ring is increased too much, it becomes difficult to rotate the correction ring while performing a microscopic examination, so that focusing becomes difficult. Furthermore, if the amount of rotational force is excessively large, the cam portion of the correction ring and the screw that is in pressure contact with the cam portion will be deformed or damaged, greatly affecting the aberration correction accuracy. For this reason, the rotational force amount of the correction ring and the load applied to the cam portion and the like must be set to appropriate values.

  From this point of view, when looking at the configuration of the objective lens described in Patent Document 2, the objective lens described in Patent Document 2 has a ring member that can move along a screw thread provided in the objective cylinder. (35) is provided, and a coil spring (36) is disposed between the ring member (35) and the correction ring (32). This objective lens can change the installation length of the coil spring (36) by moving the ring member (35) in the direction along the optical axis, and can arbitrarily adjust the rotational force amount of the correction ring (32). Note that the load applied to the objective lens by the coil spring (36) is minimal when the ring member (35) as shown in FIGS. 3 and 4 of Patent Document 2 is in contact with the objective cylinder (30). Value. However, since the load applied to the objective lens cannot be adjusted below that value, it is difficult to set the load to an appropriate value. The objective lens is provided with a coil spring (9) in addition to the coil spring (36). The load of the coil spring (9) acts in the same direction as the load of the coil spring (36). Therefore, even if the coil spring (9) is provided, the load applied to the objective lens is not reduced.

  In addition, when a coil spring is used to move the correction lens group or the like as in the objective lens with a correction ring as described in Patent Document 2, the coil spring has a direction across the optical axis during the movement. Load and displacement occur. When such a load or deviation occurs, the correction lens group or the like does not move along the optical axis, resulting in eccentricity. In addition, when the contraction range at the time of use of a coil spring is made constant, the free length of a coil spring becomes long. Therefore, as the amount of deflection increases, such a load or displacement increases, and eccentricity tends to occur. In the case of an objective lens used in a microscope, since the movement of the correction lens group in the direction along the optical axis is as long as about 2.0 mm, the influence cannot be ignored.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to set the rotational force amount of the correction ring and the load applied to the correction ring to appropriate values. An objective lens with a correction ring that can be moved along the optical axis without decentering the correction lens group by minimizing or eliminating the influence of the load or displacement generated in the direction crossing the optical axis by the compression member It is to be.

  In order to achieve the above object, an objective lens with a correction ring according to the present invention is an objective lens with a correction ring that moves a correction lens group in a direction along the optical axis in response to rotation of the correction ring. A plurality of compression members are provided to press the correction lens group frame holding the lens group.

  In the objective lens with a correction ring according to the present invention, the plurality of compression members may be configured such that the first compression member that presses the correction lens group lens frame toward the distal end and the correction lens group lens frame toward the distal end. The second compression member is preferably pressed in the opposite direction.

  In the objective lens with a correction ring of the present invention, the load applied by the first compression member and the load applied by the second compression member on the correction lens group lens frame are not the same magnitude. It is preferable.

  In the objective lens with a correction ring of the present invention, it is preferable that the compression member is a coil spring.

  According to the objective lens with a correction ring of the present invention, the amount of rotational force of the correction ring and the load applied to the correction ring and the like can be set to appropriate values, and the load and displacement generated in the direction crossing the optical axis by the compression member can be set. The correction lens group can be moved along the optical axis without decentering or removing the influence minutely.

  Prior to the description of the embodiments, as a conventional example, the configuration of an objective lens with a correction ring that is generally used at present, and the rotational force amount of the correction ring and the correction ring in such a configuration will be described with reference to FIGS. The value of the load applied to the above will be described. FIG. 3 is a partial cross-sectional view showing the configuration of a conventional objective lens with a correction ring, and FIG. 4 shows the surface provided with the cam portion of the correction ring used in the conventional objective lens with a correction ring as viewed from the direction along the optical axis. FIG. 5A is a cross-sectional view showing the relationship between a correction ring and a screw used in a conventional objective lens with a correction ring, and FIG. 5B is a cross-sectional view of FIG. 5A viewed from above. FIG. 6 is a schematic diagram showing the shape of a coil spring generally used for an objective lens with a correction ring, and FIG. 7 is a graph showing load characteristics depending on the deflection amount of the coil spring.

  First, the configuration of an objective lens with a correction ring that is generally used at present will be described with reference to FIGS. As shown in FIG. 3, the objective cylinder 1 of the objective lens with a correction ring includes a lens unit 2 composed of a plurality of lenses. The objective lens with a correction ring is arranged so that the lens unit 2 faces the cover glass CG. Single lenses or cemented lenses constituting the lens unit 2 are held by respective lens frames 3. The correction lens group 2a, which is one of the cemented lenses constituting the lens unit 2, is held by a correction lens group lens frame 3a to which screws 4 are attached. Further, a cover 5, an index ring 6, and a correction ring 7 are attached to the objective cylinder 1 in order from the distal end side. The correction ring 7 is sandwiched between the index ring 6 and the objective cylinder 1. Further, the correction ring 7 is rotatable within a certain range around the optical axis of the lens unit 2. A cam portion 7a having a cam portion end surface 7a1 is formed inside the correction ring 7, and a scale is written on the outer peripheral surface. In addition, a coil spring 8 is disposed as a compression member between the objective cylinder 1 and the correction lens group frame 3a.

As shown in FIGS. 3 and 4, the correction ring 7 is formed with a stopper groove 7 b having a stopper groove end surface 7 b ₁ . A stopper screw 9 is attached to the correction lens group frame 2a at a position opposite to the screw 4 across the optical axis. The range in which the correction ring 7 can be rotated is limited to a certain range by these members and parts.

  As shown in FIGS. 3 and 5A, the screw 4 is pressed against the cam portion 7 a of the correction ring 7 by a coil spring 8. Therefore, as shown in FIG. 5B, when the correction ring 7 is rotated by the action of the cam portion 7a, the screw 4 can be moved in the direction along the optical axis. At this time, the correction lens group frame 3a moves integrally with the screw 4, so that the correction lens group 2a held by the correction lens group 3a can also be moved.

  In such an objective lens with a correction ring, the load of the coil spring applied to the correction ring or the like is determined by the specification of the coil spring and the contraction range during use. In general, the load is preferably set to a value within a range of about 1 to 1.8 [N] (hereinafter referred to as an appropriate range). Further, when this load is within an appropriate range, the amount of rotational force of the correction ring is also an appropriate value. The appropriate range varies depending on the weight of the correction lens group and the correction lens group frame that holds the correction lens group, the amount of clearance generated between the correction lens group frame and the objective cylinder, the viscosity of the lubricating oil used, and the like. To do.

  However, in such an objective lens with a correction ring, the arrangement of a single lens or a cemented lens constituting the lens unit and a lens frame for holding them is fixed in advance. Therefore, the specifications of the coil springs arranged adjacent to them and the contraction range at the time of use have limitations such as having to be within a predetermined space. For these reasons, it is difficult to set the load applied to the correction ring or the like within a proper range.

  Here, the specification of a general coil spring used for such an objective lens with a correction ring will be described with reference to FIGS. In general, the coil spring has a shape as shown in FIG. 6, and the amount of deflection increases as it is compressed as shown in FIG. 7, and the load applied by the coil spring to the member to which the coil spring is pressed is also increased. It will increase. Note that in a state of contraction to some extent, that is, in a state in which the amount of deflection is large to some extent, the load increases linearly according to the amount of deflection as in the range ab in FIG. In such a state, it is relatively easy to adjust the load. Therefore, it is desirable that the coil spring is always mounted so as to be in such a state when used for an objective lens with a correction ring.

When the amount of deflection of the coil spring is within the range ab in FIG. 7, the following conditional expression (1) is established.
P = K · δ (1)
However,
P: Load [N]
K: Spring constant [N / mm]
δ: Deflection amount [mm]
It is.

The spring constant K of the coil spring can be derived from the following conditional expression (2).
K = Gd ⁴ / 8ND ³ (2)
However,
G: Coefficient of transverse elasticity of coil spring material [N / mm ² ]
d: Diameter of the coil spring material [mm]
N: Effective number of turns of coil spring
D: Coil spring average diameter [mm]

  However, as shown in FIG. 7, when the amount of deflection exceeds a certain value (value shown as b in the figure), adjacent coils start to contact each other from both ends of the coil spring itself, and the coil spring The load increases rapidly in a non-linear manner with respect to the deflection amount, and the conditional expression (1) is not satisfied.

Next, a general coil spring used for an objective lens with a correction ring will be described using specific numerical data. The specification of this coil spring is as follows.
Material: Piano wire
Material transverse elastic modulus (G): 78000 [N / mm]
Material diameter (d): 0.6 [mm]
Coil average diameter (D): 15 [mm]
Total volume: 6
Effective number of turns (N): 4
Free length: 23 [mm]
Coil spring length at maximum compression: 3.6 [mm]
Shrinkage range during use: 6-7 [mm]
Deflection amount during use (δ): 17 to 16 [mm]
Maximum deflection: 19.4 [mm]
Spring constant (K): 0.094 [N / mm ² ]

In this coil spring, the amount of deflection during use is 82 to 88% of the maximum amount of deflection. Further, when the deflection amount exceeds about 85% of the maximum deflection amount, the end windings provided at both ends of the coil spring and the effective winding coil in the vicinity thereof come into contact with each other, so the load of the coil spring is nonlinear with respect to the deflection amount. Starts to increase rapidly. That is, this coil spring is used within the range of a ₁ -b ₁ in FIG.

  Further, according to the conditional expression (1), when the deflection amount (δ) = 16 [mm] (coil spring length = 7 [mm]), the coil spring has a load (P) = 1.504 [N]. This value is within the appropriate range. However, when the deflection amount (δ) = 17 [mm] (coil spring length = 6 [mm]), the deflection amount is 85% of the maximum deflection amount (in this case, 19.4 × 0.85 = 16.49 [16]). mm]), the conditional expression (1) does not hold, and the value of the load (P) greatly exceeds the upper limit value P = 1.8 [N] of the appropriate range.

  By the way, when there is a structural limitation like a coil spring generally used for an objective lens with a correction ring, the material diameter of the coil spring is reduced as a method for avoiding a sudden change in the deflection amount of the coil spring load. And a method of reducing the effective number of turns of the coil spring.

  When these methods are employed, in FIG. 7 which is a graph showing the load characteristics depending on the deflection amount of the coil spring, b, which is a value in which the load of the coil spring rapidly increases nonlinearly with respect to the deflection amount, is shifted to the right. That is, the range in which the conditional expression (1) is satisfied, that is, the range in which the change in the coil spring load is stabilized is widened, and a sudden change with respect to the deflection amount of the coil spring load is less likely to occur.

However, as can be seen from the conditional expressions (1) and (2), when the material diameter of the coil spring is reduced, the spring constant is greatly reduced, that is, the change in the coil spring load with respect to the deflection amount is significantly reduced. Resulting in. For example, when the material diameter is changed from 0.6 [mm] to 0.5 [mm], the load obtained from the same deflection amount is 60% or less ((0.5 / 0.6) ⁴ = 0.58). Therefore, when this method is used, if the contraction range is limited like that used for an objective lens with a correction ring, a sufficient amount of deflection cannot be obtained, and only a small load that is less than the appropriate load can be obtained. Further, if the load is too small, a load or a deviation is generated in a direction crossing the optical axis.

  On the other hand, when the effective number of turns of the coil spring is decreased, the spring constant increases, that is, the change in the load of the coil spring with respect to the deflection amount increases. For this reason, when this method is used, it is difficult to set the value of the coil spring load within a proper range.

  As described above, in the configuration of the objective lens with a correction ring that is generally used at present, the load of the coil spring cannot be set to a value within an appropriate range. For this reason, the amount of rotational force of the correction ring cannot be set to an appropriate value, and deformation or breakage occurs in the member in contact with the coil spring or the member disposed around the member.

  In addition, in the configuration of the objective lens with a correction ring that is generally used at present, there is no special means for suppressing or eliminating the load or deviation generated in the direction crossing the optical axis. The movement of the screw, the correction lens group lens frame, and the correction lens group does not follow the optical axis, resulting in decentration.

  In the following, embodiments of the present invention will be described with reference to two illustrated examples.

  First, the configuration of the objective lens with a correction ring according to the first embodiment will be described with reference to FIGS. 1 and 7. FIG. 1 is a partial cross-sectional view showing a configuration of an objective lens with a correction ring according to the present embodiment, and FIG. 7 is a graph showing a load characteristic depending on a deflection amount of a coil spring. In addition, some members and parts in the objective lens with a correction ring of the present embodiment have substantially the same shape and function as those of the conventional objective lens with a correction ring described with reference to FIGS. Therefore, the configuration of the present embodiment will be described only for members and configurations different from the objective lens with a correction ring. Moreover, about the member and site | part, the same code | symbol as the case of FIGS. 3-5 is attached | subjected, and description is abbreviate | omitted.

  Unlike the conventional example, the objective lens with a correction ring of the present embodiment includes two coil springs, a coil spring 8a and a coil spring 8b, as compression members. Among these coil springs, the coil spring 8a as the first compression member is disposed between the objective cylinder 1 and the correction lens group lens frame 3a, similarly to the coil spring 8 as the compression member of the conventional example. On the other hand, the coil spring 8b as the second compression member is disposed at a position opposite to the coil spring 8a with the correction lens group lens frame 3a interposed therebetween.

  Of these compression members, the coil spring 8a, which is the first compression member, is connected to the correction lens group frame 3a, the screw 4, and the correction ring 7 in the same manner as the coil spring 8 which is the compression member of the conventional example. A load is applied so as to press toward the tip of the attached objective lens. On the other hand, the coil spring 8b as the second compression member applies a load so as to press the correction lens group frame 3a and the like in a direction opposite to the tip direction of the objective lens with the correction ring. The screw 4 is pressed against the cam portion 7a of the correction ring 7 by a load generated by a difference between the load of the coil spring 8a and the load of the coil spring 8b.

  Since the present embodiment has such a configuration, the load applied to the correction ring and the rotational force amount of the correction ring are determined by the difference between the load of the coil spring 8a and the load of the coil spring 8b. Therefore, the compression member of the present embodiment will be described in detail.

  First, the coil spring 8a, which is the first compression member of this embodiment, will be described using specific numerical data.

The specifications of the coil spring 8a used in this embodiment are as follows.
Material: Piano wire
Material transverse elastic modulus (G): 78000 [N / mm]
Material diameter (d): 0.6 [mm]
Coil average diameter (D): 15 [mm]
Total number of turns: 5
Effective number of turns (N): 3
Free length: 23 [mm]
Coil spring length at maximum compression: 3.0 [mm]
Shrinkage range during use: 6-7 [mm]
Deflection amount during use (δ): 17 to 16 [mm]
Maximum deflection: 20 [mm]
Spring constant (K): 0.126 [N / mm ² ]

  In this coil spring 8a, the amount of deflection during use is 80 to 85% of the maximum amount of deflection. That is, the value of the deflection amount when the coil spring 8a is used is a value within the range ab in FIG. 7, that is, a value within a range where the conditional expression (1) is satisfied. Accordingly, the load of the coil spring 8a does not change suddenly during use.

  However, the effective number of turns of the coil spring 8a is 3, which is smaller than the effective number of turns of the conventional coil spring. Therefore, according to the conditional expression (1), the coil spring 8a has a load (P) = 2 [N] when the deflection amount (δ) = 16 [mm] (coil spring length = 7 [mm]). When the deflection amount (δ) = 17 [mm] (coil spring length = 6 [mm]), the load (P) = 2.125 [N]. That is, the load of the coil spring 8a is always larger than 1.8 [N] which is the upper limit value of the appropriate range during use.

  Next, the coil spring 8b, which is the second compression member of this embodiment, will be described using specific numerical data.

The specification of the coil spring 8b used in the present embodiment is as follows.
Material: Piano wire
Material transverse elastic modulus (G): 78000 [N / mm]
Material diameter (d): 0.5 [mm]
Coil average diameter (D): 14 [mm]
Total volume: 6
Effective number of turns (N): 4
Free length: 20 [mm]
Coil spring length at maximum compression: 3.0 [mm]
Shrinkage range during use: 9 to 10 [mm]
Deflection amount during use (δ): 11 to 10 [mm]
Maximum deflection: 17 [mm]
Spring constant (K): 0.056 [N / mm ² ]

  In the coil spring 8b, the amount of deflection during use is 59 to 65% of the maximum amount of deflection. That is, the value of the deflection when the coil spring 8b is used is a value within the range ab in FIG. 7, that is, a value within the range where the conditional expression (1) is satisfied. Accordingly, the load of the coil spring 8b does not change abruptly during use.

  However, the material diameter of the coil spring 8b is 0.5 [mm], which is thinner than the material diameter of the coil spring of the conventional example. Therefore, according to the conditional expression (1), the coil spring 8b has a load (P) = 0.56 [N] when the deflection amount (δ) = 10 [mm] (coil spring length = 10 [mm]). When the deflection amount (δ) = 9 [mm] (coil spring length = 11 [mm]), the load (P) = 0.616 [N]. That is, the load of the coil spring 8b is always smaller than 1 [N], which is the lower limit value of the appropriate range during use.

  As described above, the load values of the two coil springs 8a and 8b, which are compression members in the present embodiment, do not change abruptly during use, but are not within the proper range. However, in the objective lens with a correction ring of the present embodiment, as described above, it is arranged so that the excess load by one compression member cancels out the load by the other compression member.

  Specifically, when the amount of deflection of the coil spring 8a is minimized and the amount of deflection of the coil spring 8b is maximized, that is, when the correction ring 7 is located farthest from the tip, the load of the coil spring 8a is 2 [N]. Since the load of the coil spring 8b is 0.616 [N], the load of the entire compression member is 1.384 [N]. Conversely, when the amount of deflection of the coil spring 8a is maximized and the amount of deflection of the coil spring 8b is minimized, that is, when the correction ring 7 is located closest to the tip, the load of the coil spring 8a is 2.125 [N]. Since the load of the coil spring 8b is 0.56 [N], the load of the entire compression member is 1.565 [N]. Therefore, the load applied to the correction lens group frame 3a by the two compression members of the present embodiment is 1.384 to 1.565 [N], which is a value within an appropriate range.

  As described above, in the objective lens with a correction ring of the present example, the value of the load applied to the correction lens group lens barrel 3a is a stable value proportional to the amount of deflection of the compression member when in use. Therefore, the correction lens group frame 3a, the screw 4 and the correction ring 7 are not damaged or deformed, and naturally, the rotational force amount of the correction ring is also an appropriate value.

  In addition, since the load in the direction along the optical axis is small, the coil spring 8b which is the second compression member in the present embodiment is likely to generate a load or a deviation in the direction crossing the optical axis. Therefore, in the present embodiment, the free length and the amount of deflection of the coil spring 8b are made smaller than usual so as to suppress the occurrence of load and displacement in the direction crossing the optical axis. However, even if the specifications of the compression member itself are adjusted in this way, due to errors in the manufacture of members other than the compression member constituting the objective lens with a correction ring, the compression member has a load or a deviation in the direction crossing the optical axis. Will occur.

  For this reason, in this embodiment, the arrangement of the coil spring 8a as the first compression member can be offset so that the load and the displacement in the direction across the optical axis generated by the coil spring 8b as the second compression member can be offset. And the specifications are adjusted. That is, in this embodiment, even if a load or deviation occurs in a direction across the optical axis in one compression member, such a load or deviation can be offset by another compression member. Therefore, when the configuration of this embodiment is used, the load and the deviation in the direction crossing the optical axis that occurs in the compression member during use can be made even smaller than in the conventional example, and the correction lens group can be decentered. It is possible to move along the optical axis without making it.

  Next, the configuration of the objective lens with a correction ring according to the second embodiment will be described with reference to FIG. FIG. 2 is a partial cross-sectional view showing the configuration of the objective lens with a correction ring according to the present embodiment. In addition, some members and parts in the objective lens with a correction ring of the present embodiment are substantially the same in shape and function as those of the first embodiment described with reference to FIG. 1 and the conventional example described with reference to FIGS. It has. Therefore, the configuration of the present embodiment will be described only for members and configurations different from those of the objective lens with a correction ring. Further, those members and parts are denoted by the same reference numerals as those in FIGS. 1 and 3 to 5, and description thereof is omitted.

  The objective lens with a correction ring of the present embodiment includes two coil springs, a coil spring 8c and a coil spring 8d, instead of the coil spring 8a as the first compression member in the first embodiment. Among these coil springs, the coil spring 8c is disposed between the objective cylinder 1 and the correction lens group lens frame 3a, like the conventional coil spring 8 and the coil spring 8a of the first embodiment. The coil spring 8d is disposed between the correction lens group lens frame 3a and the lens frame 3 adjacent to the correction lens group lens frame 3a and disposed on the objective cylinder 1 side. The coil spring 8b, which is the second compression member, is disposed at a position opposite to the first compression member with the correction lens group lens frame 3a interposed therebetween, as in the first embodiment. These coil springs have different specifications such as effective coil diameter.

  Since the present embodiment has such a configuration, the load of the first compression member, that is, the spring constant of the first compression member is determined by the sum of the spring constants of the coil spring 8c and the coil spring 8d.

  If the number of compression members increases as in the present embodiment, the degree of freedom for setting the effective number of turns, material diameter, coil average diameter and the like of these members increases. Therefore, it becomes easy to set the rotational force amount of the correction ring and the load applied to the correction ring to appropriate values. Furthermore, it becomes easy to cancel a load or a deviation in a direction crossing the optical axis, which occurs in one compression member during use, by another compression member.

  In the present embodiment, three coil springs that are compression members are provided. However, if more space can be secured in the objective lens with a correction ring, four or more coil springs may be provided.

  The present invention is not limited only to the forms as in the two embodiments described above, and may be appropriately modified without departing from the scope of the invention.

3 is a partial cross-sectional view illustrating a configuration of an objective lens with a correction ring according to Embodiment 1. FIG. FIG. 6 is a partial cross-sectional view illustrating a configuration of an objective lens with a correction ring according to a second embodiment. It is a partial cross section figure which shows the structure of the conventional objective lens with a correction | amendment ring. It is the figure which looked at the surface provided with the cam part of the correction ring used for the conventional objective lens with a correction ring from the direction along an optical axis. (A) is sectional drawing which shows the relationship between the correction | amendment ring and bis | screw used for the conventional objective lens with a correction | amendment ring, (b) is sectional drawing which looked at (a) from the top. It is a figure which shows the shape of the coil spring generally used for the objective lens with a correction | amendment ring. It is a graph which shows the load characteristic by the deflection amount of a coil spring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective cylinder 2 Lens part 2a Correction lens group 3 Mirror frame 3a Correction lens group Mirror frame 4 Screw 5 Cover 6 Index ring 7 Correction ring 7a Cam part 7a ₁ Cam part end surface 7b Stopper groove 7b ₁ Stopper groove end surface 8, 8a, 8b , 8c, 8d Coil spring 9 Stopper screw CG Cover glass

Claims (4)

An objective lens with a correction ring that moves the correction lens group in a direction along the optical axis in response to rotation of the correction ring,
An objective lens with a correction ring, comprising: a plurality of compression members that press a correction lens group frame holding the correction lens group.   The plurality of compression members are a first compression member that presses the correction lens group lens frame in the tip direction and a second compression member that presses the correction lens group lens frame in a direction opposite to the tip direction. The objective lens with a correction ring according to claim 1, wherein the objective lens has a correction ring.   The correction according to claim 2, wherein the load applied by the first compression member and the load applied by the second compression member to the correction lens group lens frame are not the same magnitude. Objective lens with ring.   The objective lens with a correction ring according to any one of claims 1 to 3, wherein the compression member is a coil spring.