JPH049814A - Objective lens for microscope - Google Patents

Abstract

PURPOSE:To form the objective lens which is usable for the ultraviolet and far ultraviolet ray at low cost by arraying 1st - 3rd specific lens groups from the object side to the image side at specific air intervals. CONSTITUTION:The 1st - 3rd specific lens groups LG1 - LG3 are arrayed from the object side to the image side in this order at the specific air intervals. The 1st lens group LG1 consists of a lens which is made of quartz or fluorite and has positive power and the 2nd lens group LG2 consists of a lens which is made of quartz and has negative power. Further, the 3rd lens group LG3 consists of a pair of a negative lens which is made of quartz and has negative power and a positive lens which is made of fluorite at a constant air interval distance from the negative lens and has positive power, or two pairs of lenses which are isolated from each other. Consequently, the objective lens which is usable even for the ultraviolet and far ultraviolet range is formed at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an objective lens for a microscope that can be used even in the ultraviolet region, particularly in the far ultraviolet region with a wavelength of 300 tv or less.

(Prior art and its problems) As is well known, in a microscope, if the numerical aperture (NA) of the objective lens is the same, the resolution limit increases as the wavelength becomes shorter, and the resolution limit of the sample increases. You can observe every detail. Furthermore, when a sample is irradiated with ultraviolet rays, more intense fluorescence is often emitted than when irradiated with visible light. therefore,
In order to obtain more information by observing a sample using a microscope, it is desired to provide a microscope that can also be used in the ultraviolet region. For this purpose, an objective lens that can be used in the ultraviolet and deep ultraviolet regions is required.

Therefore, for example, a microscope objective lens shown in FIG. 8 has been employed as an objective lens that can be used in the ultraviolet region or deep ultraviolet region. FIG. 8 is a diagram showing the structure of this microscope objective lens 70. This objective lens 70 is
Optical Technology] Contact Magazine Vot, 25 No. 2 (1987
(February) P, L37.

As shown in the figure, the objective lens 70 consists of a first lens 71, a second lens, and a It is composed of third lens groups 72 and 73. Second lens group 72
The concave lens 72a made of quartz is replaced by the convex lens 72b made of fluorite,
72C is sandwiched and joined. Similarly to the second lens group 72, the third lens group 73 is made by sandwiching and cementing a concave lens 73a made of quartz with convex lenses 73b and 73c made of fluorite.

In this objective lens 70, each lens 71. ,72a
72c, 73a and 73c are all made of quartz or fluorite, so they can transmit ultraviolet rays and far ultraviolet rays. Therefore, the objective lens 70 can be used even in the ultraviolet region and deep ultraviolet region.

Moreover, the second lens group 72 is composed of a concave lens 72a made of quartz and convex lenses 72b and 72C made of fluorite, and the third lens group 73 is composed of a concave lens 73g made of quartz and convex lenses 73b and 73c made of fluorite. Because of this configuration, it is also possible to correct spherical aberration and chromatic aberration.

By the way, in the second lens group 72, the convex lens 72
b The concave lens 72a and the convex lens 72C are in optical contact with each other.

Also in the third lens group 73, convex lenses 73b,
The concave lens 73a and the convex lens 73c are in optical contact with each other. The reason is that, at present, there is no practical adhesive that transmits deep ultraviolet rays. Therefore, the only way to prevent total reflection at the lens cementation surface is to make optical contact with the cementation surface. Therefore, each joint surface is processed with high precision]
There is a problem in that the manufacturing cost of the objective lens 70 increases.

Therefore, the inventor of the present invention developed an objective lens for a microscope that solved the above problem in an earlier application (Japanese Unexamined Patent Publications No. 1-319719 and 1-319720, hereinafter simply referred to as the "earlier application"). Proposed. FIG. 9 is a diagram showing an example of the objective lens for a microscope according to this proposal.

According to this proposed example, the microscope objective lens 60 is composed of lenses 61 to 63 made of quartz or fluorite. And these first to third lenses 61 to 63
As shown in the figure, they are arranged in this order from the object side (left side in the figure) to the image side (right side in the figure) with a predetermined air interval. Therefore, this microscope objective lens 6
0 can be used in the ultraviolet region and deep ultraviolet region. Moreover, the lenses 61 to 63 are spaced apart from each other. In other words, there is no bonding surface in this objective lens 60. Therefore, in this microscope objective lens 60,
It becomes unnecessary to use optical contact, and the above problem is solved.

By the way, the objective lens 60 shown in FIG. 9 cooperates with an imaging lens (the detailed structure of which will be described later) to form an image of an object with a predetermined imaging magnification M on the focal plane of the imaging lens. It is configured in such a way that

The imaging magnification M at this time is the ratio of the focal length f2 of the imaging lens and the focal length Nf1 of the objective lens 60. That is,
The imaging magnification M is M−−f2/f, (+).

Additionally, in a microscope, the imaging lens is usually fixed and the objective lens is replaced to change the imaging magnification, but for this purpose it is necessary to prepare objective lenses with different focal lengths. There is.

For example, consider a case where the objective lens 6o shown in FIG. 9 is replaced with a certain objective lens to increase the imaging magnification to 175 times.

In this case, as shown in equation (1), the imaging magnification is 17
In order to increase the magnification by 5 times, it is necessary to prepare an objective lens with a focal length of 5f1. Here, if the focal length is simply increased by 5, the objective lens 60 may be expanded proportionally, for example.

However, when the objective lens 6o is replaced with an objective lens with 5x proportional magnification, as long as the pupil position is fixed, the distance from the objective lens to the object must also be increased 5x, and the objective lens needs to be replaced. After that, you will need to refocus. This significantly reduces the operability of the microscope and is not preferable. On the other hand, if the object position is fixed, the position of the pupil will move, so a fixed illumination system will change the illumination state, which is undesirable. Furthermore, by replacing the objective lens, the size of the pupil increases five times, and the amount of light used in a fixed illumination system varies.

Therefore, when increasing the imaging magnification by 1 to 5 times by exchanging the objective lens, the objective lens after the exchange has (1) a focal length 5 times that of the objective lens 60, and (2)
Even after exchanging the objective lens, there is no need to readjust the focus; in other words, it is parfocal with the objective lens 60, and (3) the position and size of the pupil are almost the same as that of the objective lens 60. It is necessary to meet the conditions.

(Object of the invention) This invention has been made in view of the above problems, and provides a microscope objective lens that can be used even in the ultraviolet region and deep ultraviolet region, with a different configuration from the objective lens according to the above-mentioned earlier application. The primary objective is to provide the following at low cost.

Furthermore, the present invention has a focal length approximately five times larger than that of the objective lens of the previous application, which cooperates with an imaging lens to form an image of an object on an imaging plane with a predetermined imaging magnification. in,
A second object of the present invention is to provide a microscope objective lens which is parfocal and whose pupil position and size are approximately equal.

(Means for Achieving the Object) In order to achieve the first object, the invention as claimed in claim 1 is arranged such that the first to third lens groups are arranged at a predetermined air interval in this order from the object side to the image side. It is arranged with . Of these first to third lens groups, the first lens group is made of quartz or fluorite and has a positive power;
The second lens group is made of quartz and includes lenses having negative power. 1. The third lens group is a lens pair consisting of a negative lens made of quartz and having negative power, and a positive lens made of fluorite and having positive power, which is spaced apart from the negative lens by a certain air distance. or two pairs of lenses spaced apart from each other.

Further, the invention according to claim 2 is capable of being replaced with an objective lens that cooperates with an imaging lens to form an image of an object on an imaging plane with a predetermined imaging magnification M; Instead, it is intended for a microscope objective lens that, when used in combination with the imaging lens, provides an imaging magnification of approximately (M/5) times.

In order to achieve the second objective, the first to third lens groups are arranged in this order from the object side to the image side with a predetermined air interval. Among these first to third lens groups, the first lens group is made of quartz or fluorite and has a positive power, and the second lens group is made of quartz and has a negative power. ing. The third lens group includes a lens pair consisting of a negative lens made of quartz and having negative power, and a positive lens made of fluorite and having positive power, which is spaced apart from the negative lens by a certain air distance. , or two pairs of lenses spaced apart from each other.

Furthermore, the powers of the first to third lens groups are φ, φ, and φ, respectively, the power of the entire system is φ, and the powers of the positive lens and negative lens constituting the lens pair in the third lens group are φ, respectively.

φ-1 The distance between the principal points of the first and second lens groups is e12
When, with the objective lens, 0.95・1φ/
φl<lφ2/φ31.05・1φ1/φ1>1φ2/
φ31.0 < Iφ+/φ-1 < 1.2.

0.8・α×Iφ21<1.1・α However, The inequality shown is satisfied.

(Function) According to the invention of claim 1, the first lens group consists of a lens made of quartz or fluorite and has a positive power, and the second lens group consists of a lens made of quartz and has a negative power, The third lens group is constituted by a lens pair consisting of a negative lens made of quartz and having a negative power and a positive lens made of fluorite and having a positive power, or by two sets of the above-mentioned lens pairs. Therefore, light in the ultraviolet region or deep ultraviolet region can pass through the objective lens, and it can be used in the ultraviolet region and deep ultraviolet region. Further, each lens is spaced apart from each other by a predetermined air gap. Therefore, there is no need for an optical contact, and the objective lens can be provided at low cost. Furthermore, the third lens group is provided with a lens pair consisting of a positive lens made of fluorite and a negative lens made of quartz. Therefore, various aberrations such as spherical aberration and chromatic aberration are corrected.

According to the second aspect of the invention, achromatization is performed by the third lens group consisting of a positive lens and a negative lens. The second lens group having large negative power makes the objective lens a so-called telephoto type, and the focal length of the objective lens is longer than its entire length.

Furthermore, by providing the first lens group having positive power, the objective lens has telecentric characteristics on the object side.

Now, looking at the above content from a different angle, the composite system of the second and third lens groups has a large focal length and plays the role of a teleconverter for the first lens group. It can also be said that the second combination system expands the focal length of the first lens group and adjusts the focal length of the objective lens to a desired value.

In order to accurately satisfy this condition, it is necessary to satisfy the following formula (%). However, in reality, the above synthetic system does not need to be a complete afocal system, and the above synthetic system has the following formula: 0.95・1φ1/φl<lφ2/φ3 l...(3
^) 1.05・1φ1 /φ1〉1φ2/φ31...
・It is sufficient to satisfy the inequalities (3A) and (3B) shown in (3B).

By the way, achromatization is performed by the lens pair of the third lens, as described above. Here, when forming an image of the object using only this lens pair, the value φ/φ−1 should be set to 1.3 to 1.3 to
It is desirable to set it within the range of 1.4. However, when the objective lens is composed of the first to third lens groups, it is better to set the correction by the lens pair excessively in order to correct the aberrations occurring in the first and second lens groups. preferable. Therefore, the value φ /φ−
1 is set within the range of 1.00 to 1.20, that is, the objective lens is set such that 1.0<Iφ+/φ−1<1. ．． 2...
- It is preferable to set so that the inequality (4) shown in (4) is satisfied.

Next, the conditions for aligning the parfocal distances are as follows: the objective lens is 0.8・α, Iφ21<1.1・α...
(5) However, the necessity of satisfying the inequality <5) shown below will be explained. In this application, the parfocal distance is defined as [. of the focal length of the objective lens. It is assumed that the image-side focal point of the objective lens is in close contact with the third lens group so as to increase the magnification by 3 times. Therefore, between the principal point spacing e12 of the first and second lens groups and the principal point spacing e23 of the second and third lens groups, the following condition is obtained. Furthermore, in order for the objective lens to have telecentric characteristics on the object side, it is necessary to align the pupil of the composite system of the second and third lens groups with the focal point of the first lens group. Therefore, the condition expressed by the following formula % is obtained. And these conditions (6
) and (7), the objective lens is required to satisfy inequality (5).

(Example) FIG. 1 is a diagram showing a first example of an objective lens for a microscope according to the present invention. As shown in the figure, the objective lens 10 is composed of first to third lens groups LG-LG3. These first to third lens groups LG
-LG3 are arranged in this order from the object side (left side in the figure) to the image side (right side in the figure) with a predetermined air interval. Further, the first lens group LG1 is composed of a lens 11 having positive power, and the second lens group LG2 is composed of a lens 12 having negative power. Further, the third lens group LG3 includes two lens pairs LP arranged with a constant air interval.

It is composed of LP2. In this lens pair LP1, negative and positive lenses 13, 14 are arranged in this order from the object side to the image side with a predetermined air interval. Also, similar to lens pair LPl, lens pair LP2 also has
Negative and positive lenses 15 and 16 are arranged in this order from the object side to the image side with a predetermined air interval.

Table 1 shows lens data of the objective lens 10 configured as described above.

Table 1 In addition, in the same table (and Tables 3 and 4, which will be explained later), r is the i-th (i-1 to 12) counting from the object side.
) is the radius of curvature of the lens surface, and dl is the distance between the i-th (i-1 to 11)-th lens surface and the (i+1)-th lens surface on the optical axis Z, counting from the object side. It is something. Also, as can be seen from the same table, lenses 12 and 13
．． 15 is made of quartz, and lenses 1, 14, and 16 are made of fluorite.

Further, the focal length f of the objective lens 10 is 150, the numerical aperture (NA) is 1760, and the image size is 1086.

Also, for the wavelength 298.011f (ns+), the first
or the power of the third lens group LG, LG, LG3 φ1°φ2. φ3 and the power φ of the entire system (objective lens 10) are φ −0,07279 and φ 2−0.52Ht, respectively.
.

φ −0,04808, φ −0,008667. Also, the power φ-1゜φ of the lens 13.14 and the power φ-2, φ+2 and ÷1 of the lens 15.16 are respectively φ −0,1 (167, φ+i-0, l199゜φ-
2--0.07990, φ+2-0.0825
It is 11. Furthermore, the principal point spacing e1° of the first and second lens groups LG1°LG is e,2−11.58.

Therefore, from the ten J self data, 0.95・1φl/φl−. 0,37.05φ Iφ
l/φ1-11.46 φ /φ l -10,92 are respectively found, and the objective lens 10 force be inequality (3^>
, it is clear that (3B) are satisfied.

Also, from the above data, 1φ+1/φ−, l−. ．． 24 φ+2/φ−21−. , 034 are found, and it is clear that the objective lens]0 satisfies inequality (4).

Furthermore, from the above data, 0.8 ・α−0,4LO7. 1-a-0,5847 are respectively found, and it is clear that the objective lens 1o satisfies inequality (5).

By the way, this objective lens 1o has a so-called infinity correction system in consideration of its application to an epi-illumination type microscope. That is, it is configured to form an image of an object on a predetermined imaging plane in combination with an imaging lens described below.

Imaging Lens> FIG. 2 is a diagram showing the configuration of an imaging lens, which is the same as the imaging lens shown in the previous application. As shown in the figure, the imaging lens 50 includes first to third lenses 51 to 53. These first to third lenses 51 to 53 are arranged in this order from the object side (left side in the figure) to the image side (right side in the figure) with a predetermined air interval.

Table 2 shows lens data of the imaging lens 50 configured as described above.

(Margins below) Table 2 In the same table, R is the first position (counting from the object side).
The radius of curvature of the lens surface (i-1 to 6), and Dl is the radius of curvature of the lens surface of the i-th (i-1 to 5) counting from the object side and (i+
1) It shows the distance between the lens surfaces on the optical axis Z with the th lens surface. Further, as can be seen from the table, the third lens 52 is made of fluorite, and the second and third lenses 52.5
3 is made of quartz. Further, the focal length f' of this imaging lens 5o is 300 mm.

Therefore, the imaging magnification M of the microscope consisting of this imaging lens 50 and the objective lens 10 according to the first embodiment 1 is as follows: M --f'/f --300/150--2.
It becomes 0.

FIGS. 3A and 3B are diagrams showing the spherical aberration and sine conditions of a lens system combining the objective lens 10 and the imaging lens 50, respectively. In addition, both figures (and FIGS. 5A and 5B, which will be explained later).

7A and 7B), symbols A-D represent wavelengths of 298.06 (rv), 202.54 (ns), and 202.54 (ns), respectively.
398.84 (nm).

The results are shown for light of 253.70 (ns).

FIGS. 3C and 3D show wavelengths of 298 and H(
FIG. 12 is a diagram showing astigmatism and distortion in terms of wavelength (nm). In FIG. 3C (and FIGS. 5C and 7C to be described later), a solid line S indicates a sagittal image plane, and a broken line M indicates a meridional image plane.

It can be seen from FIGS. 3A and 3B that this objective lens 10 has little aberration for light in the ultraviolet region and deep ultraviolet region. Therefore, it is clear that this objective lens 10 can be used in the ultraviolet region and deep ultraviolet region. Also, from FIG. 30 and FIG. 3D, objective lens 1
It is clear that the lens system using o has less astigmatism and distortion.

B. Second Embodiment FIG. 4 is a diagram showing a second embodiment of the objective lens for a microscope according to the present invention. In the objective lens 2o according to the second embodiment, the third lens group LG3 is a lens pair LP.
It has basically the same configuration as the objective lens 1o, except that the lens 1 is only rounded. Therefore, a detailed description of the configuration will be omitted here.

Table 3 shows lens data of this objective lens 2o.

(The following is a blank space) Table 3 As can be seen from the table, the lenses 22 and 23 are made of quartz, and the lenses 21 and 24 are made of fluorite.

Further, the focal length f of the objective lens 20 is 150, the numerical aperture (NA) is 1160, and the image size is 10.6.

Also, the power φl of the first to third lens groups LG, LG, and LG3 with respect to the wavelength of 298.06 (nm)
.

φ, φ3 and the power φ of the entire system (objective lens 20) are φ, -0,08094, φ2--(.4727), respectively.

φ3-0.03893, φ-0,0011
It is i863. Also, the power φ of the lens 23 and 24
.

φ. are φ---0.1367, φ-0,1415. Furthermore, the first and second lens groups LG1°LG2
The principal point interval e12 of is e,2-Jo,32.

Therefore, from the above data, 0.95・1φ1/φ1−11.541.05・1φ
1/φ1-12.75 φ/φ31 -12.14 are respectively found, and the objective lens 20 is determined by the inequality (!IA
) and (311) are clearly satisfied.

Also, from the above data, φ+/φ−1−. 035 is obtained, and it is clear that the objective lens 2o satisfies inequality (4).

Furthermore, from the above data, 0.8・α−0,4284. 1·α −0,5891 are respectively found, and it is clear that the objective lens 20 satisfies inequality (5).

This objective lens 20 is also a so-called infinity correction system, as in the first embodiment, and is combined with an imaging lens 50 shown in FIG. Therefore, this imaging lens 5
0 and the objective lens 20 according to the second embodiment described above, the imaging magnification M of the microscope is also M--f'/f--300/150--2.
It becomes 0.

FIGS. 5A and 5B are diagrams showing the spherical aberration and sine conditions of a lens system combining the objective lens 20 and the imaging lens 50, respectively. Also, Figures 5C and 5D
The figure shows astigmatism and distortion at a wavelength of 298.0 B (n■), respectively.

From FIG. 5A and FIG. 5B, it can be seen that this objective lens 20 has little aberration for light in the ultraviolet region and deep ultraviolet region. Therefore, it is clear that this objective lens 20 can be used in the ultraviolet region and deep ultraviolet region. Also, from FIG. 5C and FIG. 5D, it is clear that the objective lens 2
It is clear that the lens system using 0 has less astigmatism and distortion.

C9 Third Embodiment FIG. 6 shows a third embodiment of the objective lens for a microscope according to the present invention. The objective lens 30 according to the third embodiment has the same configuration as the second embodiment.

Therefore, the explanation thereof will be omitted here.

Table 4 shows lens data of this objective lens 30.

(The following is a blank space) Table 4 As can be seen from the table, lenses 31 to 33 are made of quartz, and lens 34 is made of fluorite.

Further, the focal length f of the objective lens 30 is 150, the numerical aperture (N^) is 1760, and the image size is 10.6.

Furthermore, the powers φ1°φ, φ3 of the first to third lens groups LG, LG, LG3 and the power φ of the entire system (objective lens 30) for wavelengths 298, 06 (nm) are φl-0, respectively. 07255, φ2--0.3907.

φ3-0.03602, φ-0,0066
It is 67. Also, the power of lens 23.24 is φ−1φ
is φ−−0.1.314, φ+−0,1348
It is. Furthermore, first and second lens groups LG.

The principal point interval of LG2 “12” is e1. z　-1. 'a5.

Therefore, from the above data, 0.95・1φI/φ1−40.341.05・1φ
l/φI −1.43 φ /φ l −10,85 are respectively found, and the objective lens 30 is determined by the inequality (8^)
, it is clear that (3B) are satisfied.

Also, from the above data, φ+/φ−1−. , 0213 are found, and it is clear that the objective lens 30 satisfies inequality (4).

Further, from the above data, 0.8 · α-OJB90 1.1 · α-0,5074 are respectively found, and it is clear that the objective lens 30 satisfies inequality (5).

Similarly to the first and second embodiments, this objective lens 30 is also a so-called infinity correction system, and is combined with an imaging lens 50 shown in FIG.

The shift force is also the imaging magnification M of the microscope consisting of the imaging lens 50 and the objective lens 30 according to the third embodiment, M --f' / f --3007.50--2,
It becomes 0.

FIGS. 7A and 7B are diagrams showing the spherical aberration and sine conditions of a lens system combining the objective lens 30 and the imaging lens 50, respectively. Also, Figures 7C and 7D
The figure shows astigmatism and distortion at a wavelength of 298.06 (nm), respectively.

It can be seen from FIGS. 7A and 7B that this objective lens 30 has little aberration for light in the ultraviolet region and deep ultraviolet region. Therefore, it is clear that this objective lens 30 can be used in the ultraviolet region and deep ultraviolet region. Also, from FIG. 7C and FIG. 7D, the objective lens 3
It is clear that the lens system using 0 has less astigmatism and distortion.

D. Effects of the first to third embodiments As described above, the objective lenses 10, 20, and 30 according to the first to third embodiments can be used in the ultraviolet region and deep ultraviolet region, and have no effect in these wavelength regions. It has excellent properties. Also, in both embodiments, the lenses are spaced apart from each other. Therefore, there is no need for an optical contact, and the objective lens can be provided at low cost.

Although not specifically explained above, in each of the examples, there is little aberration in both the visible region and the infrared region, and each objective lens 10, 20, 30 is used in the range from the infrared region to the far ultraviolet region. Confirmed that it is usable.

By the way, the objective lens 60 (
FIG. 9) is combined with the imaging lens 50 (FIG. 2) to constitute a lens system with an imaging magnification M of 110 times. That is, the focal length of the objective lens 60 is 30. On the other hand, the objective lens 10.20.30 according to the above embodiment
The focal lengths of both are 150. Therefore, by fixing the imaging lens 50 and replacing the objective lens 10 of the first embodiment with the objective lens 60, for example, the imaging magnification M can be changed from 110 times to 12 times.

Furthermore, the objective lenses 10, 20, and 30 are all at the same focal point as the objective lens 60. As a result, even after replacing the objective lens (for example, replacing the objective lens 60 with the objective lens 10), there is no need to refocus, and the operability of the microscope is improved.

Moreover, the position and size of the pupil of each objective lens 10, 20, 30 is approximately the same as that of the objective lens 60. Therefore, even if the lens is replaced, there is no significant change in the amount of light illuminating the object, and the object can be observed in good condition.

That is, the objective lens according to the above embodiment is 10°20.
30 can be said to be objective lenses that meet the second objective of the present application.

(Effects of the Invention) As described above, according to the invention of claim 1, the first lens group is made of quartz or fluorite and has a positive power, and the second lens group is made of quartz and has a negative power. The third lens group is composed of a lens pair consisting of a negative lens made of quartz and having a negative power and a positive lens made of fluorite and having a positive power, or two sets of the 1/2 lenses. Therefore, the objective lens can be used in the ultraviolet region or deep ultraviolet region.

Furthermore, since the lenses are separated from each other by a predetermined air interval, there is no need for optical contacts, and the objective lens can be provided at low cost.

Moreover, since the third lens group includes a lens pair consisting of a positive lens made of fluorite and a negative lens made of quartz, aberrations such as spherical aberration and chromatic aberration can be corrected.

According to the invention of claim 2, the second lens group having a large negative power and the third lens group are arranged in this order from the object side to the image side, thereby forming a so-called telephoto type configuration. . Therefore, the focal length of the objective lens of the present application can be made approximately five times that of the objective lens of the earlier application, while maintaining the same focal point as the objective lens of the earlier application to be replaced.

Further, since the objective lens of the present application is configured to satisfy inequality (5), it is possible to make the objective lens almost parfocal with the replacement objective lens of the previous application.

[Brief explanation of the drawing]

FIG. 1 shows the first objective lens for a microscope according to the present invention.
FIG. 2 is a diagram showing the configuration of the imaging lens, and FIG. 3A, FIG. 3B, FIG. 3C, and FIG.
FIG. 4 is a diagram showing spherical aberration, sine conditions, astigmatism, and distortion of a lens system that combines the objective lens shown in the figure and the above-mentioned imaging lens, and FIG. FIG. 5A, FIG. 5B, FIG. 5C, and FIG. 5D are diagrams showing examples, and FIGS. 5A, 5B, 5C, and 5D respectively show the spherical aberration and sine conditions of a lens system that combines the objective lens shown in FIG. 4 and the above-mentioned imaging lens. , astigmatism and distortion; FIG. 6 is a diagram showing a third embodiment of the objective lens for a microscope according to the present invention; FIGS. 7A, 7B, 7C, and Figure 7D is a diagram showing the spherical aberration, sine condition, astigmatism, and distortion of a lens system that combines the objective lens shown in Figure 6 and the above-mentioned imaging lens, respectively. and FIG. 3 are diagrams showing the configuration of conventional microscope objective lenses. 10.20.30... Objective lens, LG s... 1st lens group, LG 2... 2nd lens group, LG 3... 3rd lens group, LP, LP2... Lens pair, 50...imaging lens, 60...objective lens Fig. 2

Claims (1)

[Claims] (1) First to third lens groups are arranged in this order with a predetermined air interval from the object side to the image side, and the first lens group is made of quartz or fluorite. The second lens group includes a lens made of quartz and has a negative power, and the third lens group includes a negative lens made of quartz and has a negative power, and a constant distance from the negative lens. a lens pair consisting of a positive lens made of fluorite and having a positive power and spaced apart by an air gap of , or two lens pairs spaced apart from each other. objective lens. (2) It is replaceable with an objective lens that cooperates with the imaging lens to form an image of an object on the imaging plane with a predetermined imaging magnification M, and the imaging lens can be used instead of the objective lens. When used in combination, the imaging magnification is approximately (M/5)
A magnifying objective lens for a microscope, comprising first to third lens groups arranged in this order with a predetermined air interval from the object side to the image side, and the first lens group is made of quartz or fluorite. The second lens group includes a lens made of quartz and has a negative power, and the third lens group includes a negative lens made of quartz and has a negative power, and a negative lens thereof. and a positive lens made of fluorite and having a positive power, which are spaced apart from each other by a certain air distance, or two pairs of lenses spaced apart from each other; or the power of the third lens group is φ_1, respectively.
, φ_2, φ_3, the power of the entire system is φ, the powers of the positive and negative lenses forming the lens pair in the third lens group are φ_+ and φ_-, respectively, and the distance between the principal points of the first and second lens groups is When e_1_2, 0.95・|φ_1/φ|<|φ_2/φ_3|, 1.
05・｜φ_1/φ｜＞｜φ_2/φ_3|, 1.0<
|φ_+/φ_-|<1.2, 0.8・α<|φ_2|<1.1・α However, α=|φ_1/(e_1_2・φ_1−1)−1/(0
．． 3/φ-1/φ_1-e_1_2)| An objective lens for a microscope characterized by satisfying the following.