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Dark field microscope and its adjusting method

外国特許コード F110005368
整理番号 K01710WO
掲載日 2011年9月5日
出願国 アメリカ合衆国
出願番号 30185807
公報番号 20100202044
公報番号 8379304
出願日 平成19年5月23日(2007.5.23)
公報発行日 平成22年8月12日(2010.8.12)
公報発行日 平成25年2月19日(2013.2.19)
国際出願番号 JP2007060554
国際公開番号 WO2007136100
国際出願日 平成19年5月23日(2007.5.23)
国際公開日 平成19年11月29日(2007.11.29)
優先権データ
  • 2007JP060554 (2007.5.23) WO
  • 特願2006-144050 (2006.5.24) JP
発明の名称 (英語) Dark field microscope and its adjusting method
発明の概要(英語) A dark field microscope is capable of providing illumination with a long focal distance condenser lens having a low numerical aperture without the need for a diaphragm for an objective lens.
A method is provided for effectively adjusting its optical axis.
In particular embodiments, the dark field microscope includes; a light source for emitting illumination light; a light collecting optical system including a light collecting side condenser lens for collecting the illumination light from the light source to illuminate an observation sample; and an image forming optical system including an objective lens for receiving scattered light from the observation sample to form a magnified image of the sample, the light collecting side condenser lens is a long focal distance lens, and a light shielding member for shielding the illumination light is provided on a back focal plane or at an image forming center of it in the image forming optical system.
従来技術、競合技術の概要(英語) BACKGROUND ART
The existence of the dark field microscope is common knowledge.
The microscope includes a light source for emitting illumination light, a light collecting optical system including a light collecting side condenser lens for collecting the illumination light from the light source to illuminate an observation sample, and an image forming optical system including an objective lens for receiving scattered light from the observation sample to form a magnified image of the sample.
FIG. 1 is an explanatory diagram illustrating a principle of a conventional general dark field microscope.
Light from a light source is illuminated on an observation sample (21) in a flow cell (20) as circular illumination light (10) through a light collecting side condenser lens having a high numerical aperture.
The illumination light is scattered by the sample (21); however, the illumination light (11) itself is shielded by an aperture diaphragm (23) present within an objective lens (22).
For this reason, only scattered light (12) is emitted from the objective lens (22).
By collecting the scattered light on an imaging area of a camera, a dark field image of the sample (21) can be obtained.
Light is scattered even by a particle or a structure smaller in size than a wavelength thereof, and therefore if a dark field microscope is used, even an object having a size equal to or smaller than a wavelength of visible light can be observed.
For example, a diameter of a microtubule is as small as approximately 24 nm; however, it becomes visible by a dark field microscope having a mercury lamp as a light source.
The dark field microscope has additional advantages, for example, a device and an operation are relatively simple; a high contrast image can be obtained; a raw sample can be observed without preprocessing; supermolecular movement and morphology change can be dynamically observed; and the like.
A conventional technique relating to the dark field microscope includes ones described in Patent documents 1 to 4.
Patent document 1 relates to an illumination system capable of easily switching between a bright field and a dark field; Patent document 2 relates to a configuration capable of observing only a target micro object without reducing a resolution; Patent document 3 relates to a configuration capable of observing an extremely fine object such as a flagellum of a living bacterium; and Patent document 4 relates to high speed processable automatic focusing and increase in brightness in the dark field microscope.
Patent document 1: Japanese Unexamined Patent Publication No. H09-297266, "Microscope"
Patent document 2: Japanese Unexamined Patent Publication No. H09-15507, "Dark field microscope"
Patent document 3: Japanese Unexamined Patent Publication No. H08-122651, "Transmission dark field microscope"
Patent document 4: Japanese Unexamined Patent Publication No. H05-346532, "Automatic focusing device of microscope and dark field microscope"
The dark field microscope according to such the conventional technique requires the aperture diaphragm (23) within the objective lens (22), and is also subject to the constraint that the light collecting side condenser lens having a high numerical aperture should be used.
If illumination can be provided through a long focal distance condenser lens having a low numerical aperture, a space can be ensured above the flow cell (20), and therefore there arise advantages of expanding an application range of experimental observation, and the like.
However, a dark field microscope capable of realizing this has been absent.

特許請求の範囲(英語) [claim1]
1. A dark field microscope comprising: a light source for emitting illumination light;
a light collecting optical system including a light collecting side condenser lens for collecting the illumination light from the light source to illuminate an observation sample; and
an image forming optical system including an objective lens for receiving scattered light from the observation sample to form a magnified image of the sample, wherein the light collecting optical system is configured such that the light collecting side condenser lens is a long focal distance lens, and the illumination light is illuminated on the observation sample only through a low numerical aperture area; and
the image forming optical system is configured such that a light shielding member for constantly shielding the entire beam of the illumination light is provided at an image forming center of a conjugate image of a back focal plane of the image forming optical system, and only the scattered light emitted from the objective lens is collected on an imaging area to obtain a dark field image of the observation sample.
[claim2]
2. The dark field microscope according to claim 1, wherein a lens for forming a secondary image from a primary image, and forming the conjugate image of the back focal plane between them is disposed in the image forming optical system.
[claim3]
3. The dark field microscope according to claim 2, wherein the light shielding member disposed at the image forming center of the conjugate image of the back focal plane is a light shielding plate having a diameter of phi e=phi .f1/L (phi is a diameter of an area to be shielded on the back focal plane; f1 is a focal distance of the lens for forming the conjugate image of the back focal plane; and L is a focal distance of a second objective lens).
[claim4]
4. The dark field microscope according to claim 2, wherein the image forming optical system for forming the secondary image from the primary image comprises a plurality of lenses, and a total focal distance of lenses for forming the conjugate image of the back focal plane among the plurality of lenses is ft=L.phi e/phi (L is a focal distance of a second objective lens; phi e is a diameter of the light shielding member; and phi is a diameter of an area to be shielded on the back focal plane).
[claim5]
5. The dark field microscope according to claim 4, comprising a mirror between the primary image and the secondary image.
[claim6]
6. A dark field microscope adjusting method wherein in a configuration comprising the dark field microscope according to claim 5, and a camera for receiving an image by the dark field microscope, optical axis adjustment is performed by:
adjusting a focal point of an eyepiece lens to thereby focus on the observation sample;
adjusting a position of the light collection side condenser lens to thereby provide Koehler illumination;
adjusting a position of the image forming side lens to thereby focus the observation sample on the imaging area;
adjusting a diaphragm for a primary imaging plane and a position of a minor to thereby match a field center with a center of a camera; and
adjusting a position of the light shielding member in an optical axis direction to thereby set it at a position where background light becomes darkest.
[claim7]
7. The dark field microscope adjusting method according to claim 6, wherein the position of the light shielding member is adjusted in a direction vertical to the optical axis with a micrometer.
[claim8]
8. The dark field microscope adjusting method according to claim 6, comprising: minimizing a field diaphragm on the light collecting side condenser lens;
adjusting a black level with preventing the light from entering the camera, to thereby set a value of the level not to take a minus value;
switching the light to a camera side, and adjusting an aperture diaphragm with the observation sample being focused on, to thereby set the aperture diaphragm at a position where the image darkens; and
adjusting light intensity and the aperture diaphragm to thereby increase a light amount and narrow a numerical aperture.
[claim9]
9. The dark field microscope adjusting method according to claim 6, comprising adjusting the black level to thereby optimize a background of the observation sample.
[claim10]
10. The dark field microscope adjusting method according to claim 6, comprising adjusting the light intensity to thereby increase scattered light from the observation sample.
  • 発明者/出願人(英語)
  • NISHIZAKA TAKAYUKI
  • YASUDA RYOHEI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
国際特許分類(IPC)
米国特許分類/主・副
  • 359/385
参考情報 (研究プロジェクト等) PRESTO Structure and Function of Biomolecules AREA
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