JP2000180727A - Objective lens and observing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-resolution objective lens for a microscope in which liquid crystal is not attached to a sample by sticking an optical member, having an almost equal refractive index to that of the liquid crystal to the tip of the lens and substituting the optical member for a part formed between the tip of the lens and the sample and filled with the liquid crystal. SOLUTION: This objective lens A is used by filling a gap between the tip of lens, that is, a front lens 1 of the liquid immersed type objective lens and the sample 2 with liquid. Then, a glass-made parallel flat plate 3 which the optical member having the almost equal refractive index to that of the liquid is stuck to the lens 1 of the objective lens. Moreover, the transparent plate 3 is substituted for the part of the gap formed between the lens 1 of the objective lens and the sample 2 and filled with the liquid. When the sample 2 side of the lens 1 of the objective lens is not flat, a plano-convex lens is used in place of the plate 3. Additionally, the thickness of the plate 3 is set to be identical to that of an oil layer. At this time, it is preferable that the sample 2 be arranged as near to the plate 3 as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an observation method for observing a specimen mainly using an optical microscope, and also relates to an objective lens used in the optical microscope.

[0002]

2. Description of the Related Art The resolution of an objective lens is determined by the wavelength and the numerical aperture (hereinafter referred to as NA). Usually, when the medium on the sample side of the objective lens is air, the upper limit of the NA of the objective lens is 1. Conventionally, in order to exceed the NA of 1, it has been necessary to use a so-called liquid immersion objective that fills the space between the objective lens and the sample with liquid.

[0003]

However, the liquid immersion type objective lens has to adhere a liquid to the sample, and its use is extremely limited. In view of the above problems, it is an object of the present invention to provide a high-resolution microscope objective lens and an observation method that do not allow liquid to adhere to a specimen.

[0004]

In order to solve the above-mentioned problems, according to the present invention, in an objective lens used by filling a liquid between a lens tip and a sample, a refractive index substantially equal to the liquid is provided at the lens tip. An objective lens is provided, wherein an optical member is adhered, and a portion filled with liquid between the lens tip and the specimen is replaced with the transparent optical part.

According to the present invention, in an observation method in which an image of a sample is enlarged by an objective lens and the image of the sample is further enlarged and observed by an eyepiece, the objective lens is provided between the lens tip and the sample. An immersion type objective lens used by filling with a liquid, an optical member having a refractive index substantially equal to that of the liquid is adhered to the lens tip of the objective lens, and the optical member and the specimen are formed of an evanescent wave. An observation method characterized by being separated by an affected distance is also provided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transparent optical member adhered to the front lens of an immersion objective lens replaces a region that should be originally filled with liquid with a transparent optical member having the same refractive index. Accordingly, there is no change in the light passing through this portion, and an NA equivalent to immersion can be achieved without immersion. However, in this case, the luminous flux forming the area where the NA exceeds 1 is totally reflected on the surface of the transparent optical member,
Can't get into the air. However, when the specimen is placed very close to the transparent optical member, the NA is substantially 1 due to the evanescent wave participating in the imaging.
And a resolution substantially equivalent to that of an immersion type objective lens can be obtained. Here, the evanescent wave has an NA of 1
The luminous flux forming the region exceeding oozes into the air.

[0007] This improvement in resolution is considered that even if the diffracted light from the illuminated specimen is evanescent light, it enters the extremely close transparent optical member and travels as a traveling wave to reach the rear surface. Is also good. In this manner, higher resolution can be realized by including in the image even diffracted light in the evanescent mode, which cannot be collected normally. As a matter of course, since the sample and the transparent optical member are separated from each other, the liquid does not adhere to the sample.

[0008]

FIG. 1 is a view showing a first embodiment of an objective lens according to the present invention. The oil portion between the tip of the front lens 1 of the immersion type objective lens and the specimen 2 is replaced by a glass parallel plane plate 3 which is a transparent optical member. When the specimen side of the front lens 1 is not flat, a plano-convex lens is used instead of the parallel plane plate. The thickness of the parallel plane plate 3 is the same as the thickness D of the oil layer. At this time, the sample 2 is desirably as close as possible to the plane-parallel plate 3, but may be as far as the used wavelength λ. However, even with evanescent light, the light having a higher NA generally attenuates faster in the air. Therefore, in order to observe with high resolution, it is better to bring the sample closer. If this is expressed as a conditional expression, it is desirable that the distance δd between the parallel plane plate 3 and the specimen 2 is 0 <δd ≦ λ. δd = 0
Then, the tip of the front lens 1 will stick to the sample 2,
meaningless. On the other hand, if δd is larger than λ, the effect of the evanescent light is undesirably reduced.

The immersion type objective lens used in the present embodiment is disclosed in Japanese Patent Application Laid-Open No. 61-240218 by the same applicant, and has the specifications shown in Table 1. The refractive index and Abbe number are values for the d-line, and the focal length is normalized to 1.

[0010]

[Table 1]

[Second Embodiment] FIG. 2 is a view showing a second embodiment of the objective lens according to the present invention. The immersion type objective lens used in the present embodiment is disclosed in
No. 8107, and has the specifications of Table 2. The refractive index and Abbe number are values for d-line.

[0012]

[Table 2]

The immersion type objective lens used in the present embodiment is a so-called objective lens with a correction ring, and the thickness D of the oil layer changes by moving a part of the constituent lenses in the optical axis direction. This is an objective lens that can correct a change in spherical aberration. By using such an objective lens, the manufacturing tolerance of the parallel flat plate 3 can be reduced. That is, even if the thickness of the parallel plane plate 3 varies, the spherical aberration can be corrected by moving a part of the constituent lenses in the optical axis direction. [Third Embodiment] FIG. 3 is a view showing an embodiment of a microscope according to the present invention. The microscope of this embodiment is a so-called infinite microscope.

Since it is an infinite microscope, the objective lens used in the second embodiment is used. About 9 of objective lens A
The second objective lens B is disposed 0 mm behind. Thereby, a real image of the specimen 2 is formed. This real image is enlarged by the eyepiece C and observed. Here, the objective lens A
A parallel flat plate 3 is bonded to the front lens 1 by an adhesive. The distance between the parallel plane plate 3 and the sample 2 is δd
And the distance between the front lens 1 of the objective lens A and the specimen 2 is D +
δd. The parallel flat plate 3 may be bonded with water.

As described above, according to the above embodiments, resolution equivalent to immersion can be obtained without immersion.
Useful for industrial applications. Further, since it is only necessary to add a front lens to the original liquid immersion type objective lens, new design and manufacturing are unnecessary, leading to cost reduction.

[0016]

As described above, according to the present invention, it has become possible to provide an objective lens for a microscope and an observation method which does not cause liquid to adhere to a specimen and has a high resolution.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an objective lens according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the objective lens according to the present invention.

FIG. 3 is a diagram showing a microscope according to the present invention.

[Explanation of symbols]

 A Objective lens B Second objective lens C Eyepiece 1 Front lens of objective lens 2 Specimen 3 Parallel plane plate

Claims (2)

[Claims] 1. An objective lens which is used by filling a liquid between a lens tip and a sample, wherein an optical member having a refractive index substantially equal to that of the liquid is adhered to the lens tip, and an optical member is provided between the lens tip and the sample. An objective lens, wherein a portion filled with a liquid is replaced by the transparent optical part. 2. An observation method in which an image of a specimen is enlarged by an objective lens and the image of the specimen is further enlarged and observed by an eyepiece, wherein the objective lens is filled with a liquid between a lens tip and the specimen. An immersion type objective lens to be used, wherein an optical member having a refractive index substantially equal to that of the liquid is adhered to the lens tip of the objective lens, and the optical member and the sample are at a distance affected by an evanescent wave. An observation method characterized by being separated by an amount.