JPH043104A - Objective lens for microscope - Google Patents

Abstract

PURPOSE:To allow the use of an optical element in UV and far UV regions and to reduce the cost thereof by disposing the optical element on the position nearer the object or image side than 1st and 2nd spherical face mirrors. CONSTITUTION:The objective lens 10 is disposed with the two mirrors 12, 13 nearly concentrically so as to face each other. A meniscus lens 11 is disposed on the object side with respect to these spherical face mirrors 12, 13. The concave face 11a of the meniscus lens 11 faces the object side. Since the optical element consists of parallel plates or the meniscus lens 11 in this case, the power of the optical element can be made into zero or smaller than the power of the meniscus lens 11. The optical element is usable in the UV and far UV regions in this way and is inexpensively obtainable.

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 deep ultraviolet region with a wavelength of 300 nm 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 be used even in the ultraviolet region. For this purpose, an objective lens that can be used in the ultraviolet and deep ultraviolet regions is required.

Therefore, conventionally, as an objective lens that can be used in the ultraviolet region and deep ultraviolet region, for example, optical technology] contact magazine Vol.
25 No. 2 (February 1987) P. 137.

This objective lens is constructed by combining a plurality of quartz or fluorite lenses. Therefore, this objective lens can be used even in the ultraviolet region and deep ultraviolet region.

Only 1. Therefore, this objective lens uses a bonded lens, and an optical contact is used on the bonded surface. The reason for this is that at present there is no practical adhesive that transmits deep ultraviolet rays, and the only way to prevent total reflection at the lens joint surface is to make optical contact between the joint surfaces. .

Therefore, in this objective lens, the bonding surface is required to be processed with high precision, and there is a problem that the manufacturing cost of the objective lens increases.

Therefore, the inventor of the present application proposed an objective lens for a microscope that solved the above problem in an earlier application (Japanese Patent Laid-Open No. 1-319719 and JP-A-1.-319720, hereinafter simply referred to as the "earlier application"). Proposed. FIG. 14 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 80 is a lens 81 made of quartz or fluorite. ~83. And these first to third lenses 81
83 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 80 can be used in the ultraviolet region and deep ultraviolet region.

Moreover, the lenses 81 to 83 are spaced apart from each other.
In other words, this objective lens 80 does not have a bonding surface. As a result, this microscope objective lens 80 does not require an optical contact, and the above problem is solved.

By the way, the objective lens 80 shown in FIG. 14 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 has a composition that makes it look like an image. The imaging magnification M at this time is the ratio of the focal length f2 of the imaging lens to the focal length f1 of the objective lens 80. That is, the imaging magnification M is M--f2/f, (1).

Furthermore, in a microscope, the imaging lens is usually fixed, and the imaging magnification is changed by appropriately replacing the objective lens. Therefore, in order to change the imaging magnification, it is necessary to prepare objective lenses with mutually different focal lengths.

For example, consider a case where the objective lens 80 shown in FIG. 14 is replaced with a certain objective lens to increase the imaging magnification by (5xM).

In this case, as can be seen from equation (1), the imaging magnification is (5
×M), the focal length must be (f i / 5
) objective lens must be prepared.

Here, for example, with the same number of lenses as the objective lens 8o,
Moreover, when designing an objective lens with a focal length of (f, 15), it is necessary to increase the power of each lens.

However, when the power of each lens is increased, aberrations increase numerically. In particular, when the lens is made of a glass material with a low refractive index such as quartz or fluorite, aberrations tend to increase. Furthermore, in order to increase the power, the curvature of each lens must be increased. As a result, there arises the problem of total reflection at the boundary surface.

One way to solve these problems is to increase the number of lenses that make up the objective lens. In other words, while keeping the power of each lens relatively low, the number of lenses is increased to ensure a predetermined power. However, as the number of lenses increases, the structure of the objective lens becomes more complex. Moreover, the cost of the objective lens also increases.

Another method for solving the above problem is to use a Techa-Schwarzschild (-3chvarzchf Id) type objective lens. FIG. 15 is a diagram showing an example of a Schwarzschild type objective lens.
”(＾CADEMICPRESS 1978) P, 8
3B. This objective lens 90 is
As shown in the figure, it is composed of a concave spherical mirror 91 and a convex spherical mirror 92. In this objective lens 90, both mirrors 9192 are arranged substantially concentrically and facing each other. Although its configuration is simple, it is possible to increase its power and its focal length to cf, 15).

However, when the objective lens 80 is replaced with the objective lens 90, the object position needs to be changed from when the objective lens 80 was used, as long as the pupil position is fixed. That is, after replacing the objective lens, it becomes necessary to refocus. This significantly reduces the operability of the microscope and is not preferable. If you allow the position of the pupil to change, you can consider moving the entire objective lens so that you don't have to refocus even if you change the objective lens, but in this case, the illumination system should be fixed. If left as is, the lighting conditions tend to become inappropriate.

That is, it is difficult to replace the objective lens 90 while keeping the objective lens 80, the position of the pupil, and the position of the object the same.

Furthermore, if the size of the pupil changes when the objective lens is replaced, in a fixed illumination system, the amount of light illuminating the object will change significantly at the same time as the lens is replaced.

Therefore, by replacing the objective lens, the imaging magnification can be increased by (5
x M), the objective lens after replacement is: (1) the focal length is 115 times that of the objective lens 80;
2) Even after replacing the objective lens, there is no need to readjust the focus, that is, it is parfocal with the objective lens 80; (3) Also, the size and position of the pupil are almost equal to that of the objective lens 80; It is necessary to meet the following conditions.

(Object of the Invention) This invention has been made in view of the above problems, and provides a microscope objective that can be used in the ultraviolet region and deep ultraviolet region, with a structure different from that of the objective lens according to the above-mentioned five earlier applications. The first objective is to provide lenses at low cost.

Furthermore, the present invention has a focal length of approximately A second object of the present invention is to provide an objective lens for a microscope that has a magnification of 115 times, is parfocal, and has approximately the same size and position of the pupil.

(Means for Achieving the Object) In order to achieve the above object, the invention of claim 1 provides a convex first spherical mirror and a concave second spherical mirror arranged substantially concentrically and facing each other. It is equipped with a mirror and an optical element consisting of a meniscus lens or a parallel plate whose power is lower than that of the entire system, and the optical element is arranged on the object side or image side with respect to the first and second spherical mirrors. .

Further, in order to better achieve the first object, the invention of claim 2, in addition to the invention of claim 1, includes making the optical element made of quartz or fluorite.

Further, the invention according to claim 3 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, and furthermore, the objective lens is Instead, it is directed to a microscope objective 1 nons which, when used in combination with the imaging lens, provides an imaging magnification of approximately (5xM) times.

In order to achieve the second objective, a convex first spherical mirror and a concave second spherical mirror are arranged substantially concentrically and facing each other, and have a power smaller than that of the entire system. The optical element is provided with an optical element consisting of a meniscus lens or a parallel flat plate, and the optical element is arranged on the object side or image side of the first and second spherical mirrors.

(Function) According to the first aspect of the invention, since the optical element is composed of a parallel plate or a meniscus lens, the power of the optical element can be zero or smaller than that of the entire system. The spherical aberration of the objective lens is determined by the combination of the first and second spherical mirrors, the so-called Schwarzschild (=Sc
(hwarzchild) type objective lens, but in the case of a numerical aperture of the order of the present invention, spherical aberration is sufficiently small and poses no problem. This Schwarzschild type objective lens has no chromatic aberration because it is a reflective system, but the power of the attached meniscus lens or parallel plate is small, so
There is no need to consider the chromatic aberration caused by these as a problem. As a result, the objective lens according to the invention of claim 1 can be used even in the ultraviolet region, does not require an optical contact, and can be provided at low cost.

In particular, when the optical element is made of quartz or fluorite, the transmittance in the ultraviolet region and deep ultraviolet region is good.

Further, according to the invention of claim 3, since the optical element is composed of a parallel plate or a meniscus lens, the power of the optical element can be zero or smaller than that of the entire system, and by introducing these optical elements, It becomes possible to adjust the position of the pupil of the objective lens, so that the position of the pupil can also be the same as that of the earlier application while keeping the object position consistent with that of the earlier application. As a result, while the focal length of the objective lens is approximately 115 that of the objective lens of the previous application and the imaging magnification is (5×M) times,
The position and size of the pupils remain parfocal with those of the previous application.

(Embodiments) A. First Embodiment FIG. 1 is a diagram showing a first embodiment of a microscope objective lens according to the present invention. As shown in the figure, this objective lens 10 includes a meniscus lens 11 and a concave spherical mirror 1.
2 and a convex spherical mirror 13. In this objective lens 10, both mirrors 12 and 13 are arranged substantially concentrically and facing each other. Also,
A meniscus lens 11 is arranged on the object side (left side in the figure) with respect to these spherical mirrors 1, 2, and 13. Note that the concave surface 11a of this meniscus lens 11 faces toward the object side.

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 to 7, which will be explained later), r is the curvature of the i-th (i-1 to 4) lens surface or reflective surface counted in the order in which the ray passes from the object side. The radius and d are the i-th (
It shows the distance between the surfaces i-1 to 3) and the (i+1)-th surface on the optical axis. Further, as can be seen from the same table, the meniscus lens 11 is made of quartz.

Further, the focal length f of the objective lens 10 is 6.0, the numerical aperture (N^) is 5/12, and the image size is 110.

Also, the power φ′1 of the entire system of the meniscus lens 11 and the objective lens 10 for the wavelength 298.06 (nm)
φ are as follows.

φ' −5,536XIO, φ−0,1667 As can be seen from this, the power φ of the meniscus lens 11
' is much smaller than the power φ of the objective lens 10, and the ratio (φ'/φ) is φ'/φ−3.322x
10”.

By the way, this objective lens 10 is a so-called infinity correction system in consideration of application to an epi-illumination type microscope. That is, in combination with the imaging lens described below,
It is configured to form an image of the object on a predetermined imaging plane.

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 70 includes first to third lenses 71 to 73. These first to third lenses 71 to 73 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 70 configured as described above.

(Margin below) The radius of curvature of the lens surface in Table 2 (i-1 to 6) is also d,
represents the inter-lens distance on the optical axis Z between the i-th (i-1 to 5)-th lens surface and the (i+l)-th lens surface counting from the object side. Further, as can be seen from the same table, the second lens 71 is made of fluorite, and the second and third lenses 72
．． 73 is made of quartz. Further, the focal length f' of this imaging lens 70 is 300 mm.

Therefore, the imaging magnification M' of the microscope consisting of this imaging lens 70 and the objective lens 10 according to the first embodiment is M'--f'/f--1oo/6.0--
It becomes 50.0.

FIGS. 3A and 3C are diagrams showing spherical aberration and chromatic aberration of magnification, respectively, of a lens system that combines the objective lens 10 and the imaging lens 70. Note that both figures (and Figures 5A, 5C, 7A, 7C, and 9A, which will be explained later)
Figures 9C, 11A, 5, 11C, 13A,
In Fig. 13C), solid line A, broken line B, dashed line C,
The two-dot chain lines each have a wavelength of 298.06 (nm), 2
02.54 (nm), 398.84 (nm), 25
The results are shown for light of 3.70 (nm). Furthermore, in this embodiment, as can be seen from FIG. 1, the light beam at the center is eclipsed by the spherical mirror 13, but this is ignored for convenience when calculating the spherical aberration. Regarding the second to sixth embodiments, which will be described in detail later,
This is the same as the first embodiment described above.

Figures 3B and 3D each have a wavelength of 298°08
It is a figure showing astigmatism and distortion aberration about (nm). Note that FIG. 3B (and FIG. 5B, which will be explained later),
7B, 9B, 11B, and 13B), the solid line S indicates the sagittal image plane, and the broken line M indicates the meridional image plane.

From FIGS. 3A and 3C, it can be seen 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. 3B and FIG. 3D, it is clear that the objective lens 1
It is clear that the astigmatism and distortion aberration of the lens system using 0 is also small.

B. Second Embodiment FIG. 4 is a diagram showing a second embodiment of the objective lens for a microscope according to the present invention. The objective lens 20 according to the second embodiment has the same configuration as the objective lens 10.

Therefore, detailed explanation of the lens configuration will be omitted here.

Table 3 shows lens data of this objective lens 20.

Table 3 As can be seen from the table, the meniscus lens 21 is made of fluorite.

Further, the focal length f of the objective lens 20 is 6.0, the numerical aperture (N^) is 5/12, and the image size is 11.0.

Also, the power φ of the entire system of the meniscus lens 21 and the objective lens 20 for the wavelength 298,06 (nm)
′ and φ are as follows, respectively.

φ'-2,047x 10-', φ-0,1B6
7 As can be seen from this, the power φ' of the meniscus lens 21 is much smaller than the power φ of the objective lens 20, and the ratio (φ'/φ) is φ'/φ-1,22
8×10-”.

Similarly to the first embodiment, this objective lens 20 is also a so-called infinity correction system, and is combined with an imaging lens 70 shown in FIG. 2. So, this imaging lens 7
The imaging magnification M' of the microscope consisting of 0 and the objective lens 20 according to the second embodiment is also M'--f'/f--300/6.0--5.
It becomes 0°0.

5A and 5C are diagrams showing spherical aberration and chromatic aberration of magnification, respectively, of a lens system that combines the objective lens 20 and the imaging lens 70. Also, Figures 5B and 5
The D diagrams each have a wavelength of 298. It is a figure showing astigmatism and distortion aberration about H (r+m).

From FIG. 5A and FIG. 5C, 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. 5B 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.

In the first and second embodiments described above, a meniscus lens having a power (φ') which is considerably smaller than the power (φ) of the entire objective lens system and only 2 is provided on the object side with respect to the spherical mirror. However, the same effect can be obtained by arranging a parallel plate (φ'=0) instead of the meniscus lens.

C1 Third Embodiment FIG. 6 is a diagram showing a third embodiment of the objective lens for a microscope according to the present invention. As shown in the figure, the objective lens 30 according to the third embodiment includes a meniscus lens 31, a concave spherical mirror 32, and a convex spherical mirror 33. This objective lens 30 has both mirrors 3
2.33 are arranged almost concentrically and facing each other. Furthermore, a meniscus lens 31 is arranged on the image side (on the right side in the figure) with respect to these spherical mirrors 32 and 33. Note that the concave surface 3 of this meniscus lens 31
1a faces the object side (left side in the figure).

Table 4 shows lens data of the objective lens 30 configured as described above.

Table 4 As can be seen from the table, the meniscus lens 31 is made of quartz.

Further, the focal length f of the objective lens 30 is 6.0, the numerical aperture (N^) is 5/12, and the image size is 11.0. Further, the powers φ' and φ of the entire system of the meniscus lens 31 and the objective lens 30 for a wavelength of 298.08 (nm) are as follows, respectively.

φ' −4,141xlO”, φ−0,166
7) From this point of view, the meniscus lens 31
The power φ' of the objective lens 30 is much smaller than the power φ of the objective lens 30, and the ratio (φ'/φ) is φ'/φ−2.
It is 485X 10-'.

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 70 shown in FIG. 2.

Therefore, the imaging magnification M' of the microscope consisting of this imaging lens 70 and the objective lens 30 according to the third embodiment is also M'--f'/f--800/6.0--5.
It becomes 0.0.

FIGS. 7A and 7C are diagrams showing spherical aberration and chromatic aberration of magnification, respectively, of a lens system that combines the objective lens 30 and the imaging lens 70. Also, Figure 7B and Figure 7
Diagram D is a diagram showing astigmatism and distortion at a wavelength of 298.08 (nIl), respectively.

It can be seen from FIGS. 7A and 7C 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. 7B and FIG. 7D, it is clear that the objective lens 3
It is clear that the lens system using 0 has less astigmatism and distortion.

D. Fourth Embodiment FIG. 8 is a diagram showing a fourth embodiment of the objective lens for a microscope according to the present invention. As shown in the figure, the objective lens 40 according to the fourth embodiment is composed of a parallel plate 41, a concave spherical mirror 42, and a convex spherical mirror 43. In this objective lens 40, both mirrors 42 and 43
are arranged almost concentrically and facing each other. Also, the image side (
A parallel plate 41 is arranged on the right side of the figure.

Table 5 shows lens data of the objective lens 40 configured as described above.

Table 5 It is made in England.

Further, the focal length f of the objective lens 40 is 6.0, the numerical aperture (NA) is 5/12, and the image size is 11.0. Also, the power φ'φ of the entire system of the parallel plate 41 and the objective lens 40 for the wavelength 298.08 (nm)
are as follows.

φ′ −〇 , φ−0.1687 Therefore,
The ratio (φ'/φ) is φ'/φ−〇.

Similarly to the first to third embodiments, this objective lens 40 is also a so-called infinity correction system, and is combined with an imaging lens 70 shown in FIG. 2.

Therefore, the imaging magnification M' of the microscope consisting of this imaging lens 70 and the objective lens 40 according to the fourth embodiment is also M'--f'/f--80 (1/6.0--
It becomes 50.0.

FIGS. 9A and 9C are diagrams showing spherical aberration and chromatic aberration of magnification, respectively, of a lens system that combines the objective lens 40 and the imaging lens 70. Also, Figures 9B and 9
Diagram D is a diagram showing astigmatism and distortion at a wavelength of 298.06 (nm), respectively.

It can be seen from FIGS. 9A and 9C that this objective lens 40 has little aberration for light in the ultraviolet region and deep ultraviolet region. Therefore, it is clear that this objective lens 40 can be used in the ultraviolet region and deep ultraviolet region. Moreover, from FIG. 9B and FIG. 9D, the objective lens 4
It is clear that the astigmatism and distortion aberration of the lens system using 0 is small.

FIG. 10 shows the fifth objective lens for a microscope according to the present invention.
It is a figure showing an example. The objective lens 50 according to the fifth embodiment has the same configuration as the objective lens 30. Therefore, detailed explanation of the lens configuration will be omitted here.

Table 6 shows lens data of this objective lens 50.

Table 6 As can be seen from the table, the meniscus lens 51 is made of fluorite.

Further, the focal length f of the objective lens 50 is 6.0, the numerical aperture (NA) is 5112, and the image size is 11.0.

In addition, the power φ' of the entire system of the meniscus lens 51 and the objective lens 50 for the wavelength 298.06 (nm),
φ are as follows.

φ'--1,451X 10-', φ-0,16
As you can see from 672, meniscus lens 51
The power φ' of the objective lens 50 is much smaller than the power φ of the objective lens 50, and the ratio (φ'/φ) is φ'/φ−8,7
04x 10-'.

Similarly to the first to fourth embodiments, this objective lens 50 is also a so-called infinity correction system, and is combined with an imaging lens 70 shown in FIG. 2.

Therefore, the imaging magnification M' of the microscope consisting of this imaging lens 70 and the objective lens 50 according to the fifth embodiment is
Also, M'--f'/f--'100/6.0--
It becomes 50.0.

Figures 11A and 1. The IC diagrams are diagrams showing spherical aberration and chromatic aberration of magnification of a lens system in which the objective lens 50 and the imaging lens 70 are combined, respectively.

Moreover, FIG. 11B and FIG. 11D each show wavelength 2.
It is a figure showing astigmatism and distortion aberration about 98.06 (nm).

From FIGS. 11A and 11C, this objective lens 50
According to , it can be seen that there is little aberration for light in the ultraviolet region and far ultraviolet region. Therefore, it is clear that this objective lens 50 can be used in the ultraviolet region and deep ultraviolet region. Furthermore, from FIGS. 11B and 11D, it is clear that the lens system using the objective lens 50 has little astigmatism and distortion.

F. Sixth Embodiment FIG. 12 shows the sixth embodiment of the microscope objective lens according to the present invention.
It is a figure showing an example. The objective lens 60 according to the sixth embodiment has the same configuration as the objective lens 30. Therefore, detailed explanation of the lens configuration will be omitted here.

Table 7 shows lens data of this objective lens 60.

Table 7 As can be seen from the table, the parallel plate 61 is made of fluorite.

Further, the focal length Mf of the objective lens 60 is 6.0, the numerical aperture (NA) is 5712, and the image size is 11.0. Also, the power φ'φ of the entire system of the parallel plate 61 and the objective lens 60 for the wavelength 298.06 (ns)
are as follows.

φ'-〇, φ -0, 1H7 Therefore, the ratio (φ′/φ) is φ′/φ−0 It is.

Similarly to the first to fifth embodiments, this objective lens 60 is also a so-called infinity correction system, and is combined with an imaging lens 70 shown in FIG. 2.

Therefore, the imaging magnification M' of the microscope consisting of this imaging lens 70 and the objective lens 60 according to the sixth embodiment is
Also, M'--f'/f--300/8.0--5
It becomes 0.0.

FIGS. 13A and 13C show the objective lens 6, respectively.
FIG. 3 is a diagram showing spherical aberration and chromatic aberration of magnification of a lens system that combines a lens 0 and an imaging lens 70.

Moreover, FIG. 13B and FIG. 13D each show wavelength 2.
FIG. 3 is a diagram showing astigmatism and distortion for 98.0 ft (nm).

From FIGS. 13A and 13C, this objective lens 60
According to , it can be seen that there is little aberration for light in the ultraviolet region and far ultraviolet region. Therefore, it is clear that this objective lens 60 can be used in the ultraviolet region and deep ultraviolet region. Furthermore, from FIGS. 13B and 13D, it is clear that the lens system using the objective lens 60 has little astigmatism and distortion.

G. Effects of the first to sixth embodiments As described above, the objective lenses 10.20, 30, 40, 50.60 according to the first to sixth embodiments can be used in the ultraviolet region and deep ultraviolet region. , has excellent properties in these wavelength regions.

Further, in any of the embodiments, there is no need for an optical contact, and the objective lens can be provided at low cost.

In addition, in the above, either there was no particular explanation, or all of the embodiments had little aberration in the visible region and the infrared region, and each of the objective lenses 10, 20, 30, . :! 4
It was confirmed that 0.50.60 can be used in the range from the infrared region to the far ultraviolet region.

By the way, the objective lens 80 (
FIG. 14) is combined with the imaging lens 70 (FIG. 2),
A lens system with an imaging magnification M of 110 times is constructed. That is, the focal length of the objective lens 80 is 30. On the other hand, the objective lenses 10, 20, 3 according to the above embodiments
The focal lengths of 0, 40.50 and 60 are all 6.0. Therefore, by fixing the imaging lens 7o and replacing the objective lens 1o of the first embodiment with the objective lens 8o, for example, the imaging magnification can be increased by M (-10).
' (-50-5M) times.

Moreover, objective lenses 10, 20, 30, 40°50.6
0 are all parfocal with the objective lens 8o. As a result, even after changing the objective lens (for example, changing from objective lens 8o to objective lens 1o), there is no need to refocus, and the operability of the microscope is improved.

Moreover, each objective lens 10.20, 30, 40°50.
The lens diameter and pupil position of lens 60 are almost the same as the 8° objective lens. Therefore, even when 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, 40, and 50.60 can all be said to be objective lenses that meet the second objective of the present application.

(Effect of the invention) As described above, according to the invention of claim 1, substantially concentrically,
In addition, a convex first spherical mirror and a concave second spherical mirror are provided, which are arranged to face each other, and an optical element consisting of a meniscus lens or a parallel plate having a smaller power than the entire system is provided for the first and second concave spherical mirrors. Since it is disposed on the object side or image side of the second spherical mirror, the objective lens can be used in the ultraviolet region or deep ultraviolet region.

Furthermore, the objective lens does not require an optical contact, and can be provided at low cost.

In the invention of claim 2, in addition to the invention of claim 1, since the optical element is made of quartz or fluorite, the transmittance in the ultraviolet region and deep ultraviolet region can be made good.

According to the third aspect of the invention, since the optical element is formed by a parallel plate or a meniscus lens, the power of the optical element is zero or smaller than that of the entire system. Therefore, while maintaining good performance, it is possible to make the size of the pupil of the objective lens and its potential almost the same as in the previous application, and it is also possible to make it parfocal, so that the focus of the objective lens The distance is about 115 of the objective lens of the earlier application.
, and the imaging magnification becomes (5×M) times.

[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, astigmatism, single-lateral chromatic aberration, 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 the spherical aberration and aberration of a lens system that combines the objective lens shown in FIG. 4 and the above-mentioned imaging lens, respectively. FIG. 6 is a diagram showing a third embodiment of the objective lens for a microscope according to the present invention, and FIG. 7A, FIG. 7B, FIG. 7C, and FIG. FIG. 7D is a diagram showing spherical aberration, astigmatism, 1-magnification chromatic aberration, and distortion of a lens system that combines the objective lens shown in FIG. 6 and the above-mentioned imaging lens, respectively, and FIG. FIG. 9A, FIG. 9B, FIG. 9C, and FIG. 9D are diagrams showing a fourth embodiment of the objective lens for a microscope according to the present invention, and FIGS. 9A, 9B, 9C, and 9D each show a combination of the objective lens shown in FIG. FIG. 10 is a diagram showing a fifth embodiment of the objective lens for a microscope according to the present invention, and FIG. FIGS. 11B, 11C, and 11D are diagrams showing spherical aberration, astigmatism, 1-magnification chromatic aberration, and distortion, respectively, of a lens system that combines the objective lens shown in FIG. 10 and the above-mentioned imaging lens. , FIG. 12 is a diagram showing a sixth embodiment of the objective lens for a microscope according to the present invention, and FIGS. 123A, 13B, 13C, and 13D.
The figures show spherical aberration, astigmatism, 1x chromatic aberration, and distortion of a lens system that combines the objective lens shown in Fig. 12 and the above-mentioned imaging lens, respectively. Figs. 14 and 15 show the following: FIG. 3 is a diagram showing the configuration of a conventional objective lens for a microscope. 11.21, 31.51...meniscus lens, 41
．． 61...Parallel plate,

Claims (4)

[Claims] (1) An optical element consisting of a convex first spherical mirror and a concave second spherical mirror that are arranged substantially concentrically and facing each other, and a meniscus lens or parallel flat plate that has a smaller power than the entire system. An objective lens for a microscope, characterized in that an optical element is disposed on the object side or image side of the first and second spherical mirrors. (2) The objective lens for a microscope according to claim 1, wherein the optical element is made of quartz or fluorite. (3) The objective lens can be replaced with an objective lens that cooperates with the imaging lens to form an image of the object on the imaging plane with a predetermined imaging magnification M, and the objective lens can be replaced with the imaging lens. When used in combination, the imaging magnification is approximately (5 x M)
This is a microscope objective lens that doubles as a microscope, and includes a convex first spherical mirror and a concave second spherical mirror that are arranged substantially concentrically and facing each other, and a meniscus lens that has a smaller power than the entire system. Alternatively, an objective lens for a microscope is provided with an optical element made of a parallel flat plate, and the optical element is arranged on the object side or the image side with respect to the first and second spherical mirrors. (4) The objective lens for a microscope according to claim 3, wherein the optical element is made of quartz or fluorite.