JP3029040B2 - X-ray microscope - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray microscope.

[Conventional technology]

2. Description of the Related Art In recent years, an X-ray microscope using soft X-rays has been developed since a biological sample can be observed at a high resolution in a living state without pretreatment.

In this type of conventional X-ray microscope, an illumination system composed of an X-ray light source and a condenser lens and an imaging system composed of an objective lens and an X-ray detector basically absorb soft X-rays by air. In order to avoid as much as possible, each sample is placed in a vacuum container, and soft X-rays enter and exit through windows provided in both vacuum containers, and a sample is placed between the windows (in air). It was arranged to observe the sample. As the condenser lens or the objective lens, a Schwarzschild optical system in which a multilayer film having a high reflectance for soft X-rays of a specific wavelength is laminated on a reflecting surface, a Walter optical system using total reflection, A zone plate utilizing diffraction is used.

However, when alignment and focusing with respect to an observation target are performed using soft X-rays, if the displacement or blurring is large, vacuum breaking and evacuation must be performed many times, resulting in poor operability and enormous time. There was an inconvenience. There is also a demand for observing the same sample with both visible light and soft X-rays.

In order to solve these problems, for example, Japanese Patent Laid-Open Publication No. 64-3600 discloses that a Fresnel zone plate for soft X-rays and a Fresnel zone plate for visible light are arranged concentrically, An X-ray microscope has been proposed in which an alignment and focusing can be performed and observation can be performed by using the method, and then a vacuum is applied to perform observation using soft X-rays.

[Problems to be solved by the invention]

However, when the Fresnel zone plate is used as an objective lens as described above, in addition to the fact that the numerical aperture cannot be made too large, noise due to light of an unnecessary diffraction order is generated, so that sufficient imaging performance cannot always be obtained. There was something.

In view of the above problems, an object of the present invention is to provide an X-ray microscope that has improved operability, enables observation using both visible light and soft X-rays, and has sufficient imaging performance. .

[Means and Actions for Solving the Problems]

An X-ray microscope according to the present invention includes: a condenser lens that irradiates an X-ray emitted from an X-ray source onto an observation target; and a reflective objective lens that focuses the X-ray from the observation target at a predetermined position. In an X-ray microscope, a visible light source, illumination means for guiding light from the visible light source along substantially the same optical axis as the X-rays and irradiating the observation object, and applying light from the observation object to a predetermined position The objective lens for visible light that focuses at the position of, alignment and focusing with visible light can be performed, and a microscope optical system for both visible light and soft X-rays is provided. The objective lens for the line is a reflection type lens having good imaging performance.

The visible light objective lens may be a soft X-ray reflective objective lens, or both may be separate optical systems. In the case where the visible light objective lens is a soft X-ray reflective objective lens, the visible light objective lens can be inserted into and removed from the observation target object in an optical path to a predetermined position where light emitted from the observation object is focused. If a correction lens is provided, it becomes possible to correct aberrations in the case of observation using visible light.

〔Example〕

Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a sectional view of a first embodiment of the X-ray microscope according to the present invention. 1 is an X-ray source, 2 is a condenser lens composed of a Schwarzschild optical system, which constitutes an illumination system for X-rays, and a vacuum vessel 3 for minimizing absorption of soft X-rays by air. Is placed inside. The soft X-rays focused by the condenser lens 2 are applied to a window 4 made of a thin film of Si ₃ N ₄ provided in the vacuum vessel 3.
And irradiates the sample 5 placed in the air. Reference numeral 6 denotes an objective lens composed of a Schwarzschild optical system having the same structure as that of the condenser lens 2, reference numeral 7 denotes an X-ray detector connected to a display or the like (not shown), reference numeral 8 denotes a long wavelength band disposed on the front surface of the soft X-ray detector 7. Soft X-ray filters as cutting means constitute an enlarged imaging system for X-rays, and are placed in a vacuum vessel 9 in order to minimize absorption of soft X-rays by air. . Then, the soft X-ray transmitted and diffracted through the sample 5 enters through a window 10 made of a thin film of Si ₃ N ₄ provided in the vacuum vessel 9 and is focused on the soft X-ray detector 7 by the objective lens 6. It has become. The Schwarzschild optical system constituting the condenser lens 2 and the objective lens 6 is formed by coating a multilayer film having a reflectance distribution with respect to soft X-rays in a predetermined wavelength range. It also has a large reflectivity, and can be used as a visible light lens.

Reference numeral 11 denotes a visible light source, 12 denotes a window provided on the side wall of the vacuum vessel 3 and is opened and closed by a shutter 13, and 14 denotes a visible light source which is detachably disposed in an optical path between the X-ray source 1 and the condenser lens 2. A prism which emits a light source 11, reflects visible light that has entered the vacuum chamber 3 from the window 12 and guides it along the substantially same optical axis as the soft X-rays, and makes the objective lens 2 enter the objective lens 2. 2 together with the illumination system for visible light. Numeral 15 is disposed in the optical path between the objective lens 6 and the soft X-ray detector 7 so as to be freely inserted and removed, reflects visible light from the objective lens 6 and separates the visible light from the optical axis of the soft X-ray. A prism that forms an image at a position conjugate with the light receiving surface of the line detector 7 and constitutes an enlarged imaging system for visible light together with the objective lens 8. Reference numeral 16 denotes an eyepiece provided on the side wall of the vacuum vessel 9 so that a visible light image on an optical path separated by the prism 15 can be observed from outside the vacuum vessel. Is the shutter
17 makes it possible to block.

Since the present embodiment is configured as described above, first, the vacuum sources 3 and 9 are not evacuated and the visible light source 11 is turned on while the X-ray source 1 is turned off, and the prisms 14 and 15 are placed in the optical path. When the shutter is inserted and the shutters 13 and 17 are further opened, the visible light emitted from the visible light source 11 enters the vacuum vessel 3 through the window 12, and its optical path is bent by the prism 14 and guided to the condenser lens 2. The visible light guided to the condenser lens 2 is focused by the condenser lens 2 and illuminates the sample 5 through the window 4. The visible light transmitted through the sample 5 is guided to the objective lens 6 through the window 10, and the visible light guided to the objective lens 6 is converged by the objective lens 6,
After the optical path is bent by the prism 15, it is enlarged and formed as a sample image at a position conjugate with the light receiving surface of the soft X-ray detector 7. Then, this sample image is visually observed through the eyepiece lens 16. Therefore, the operator can observe the image of the sample 5 with visible light, and can perform alignment and focusing while observing with the visible light. Therefore, operability is greatly improved.

Next, the prisms 14 and 15 are retracted out of the optical path, the shutters 13 and 17 are closed, the visible light source 11 is turned off, the vacuum containers 3 and 9 are evacuated, and the X-ray source 1 is turned on. Soft X-rays emitted from a source 1 are focused by a condenser lens 2 and illuminate a sample 5 through a window 4.
The soft X-ray transmitted and diffracted through the sample 5 is guided to the objective lens 6 through the window 10 and receives the focusing action of the objective lens 6, passes through the soft X-ray filter 8, and then receives the light receiving surface of the soft X-ray detector 7. The image is magnified as a sample image. Therefore, the operator can observe the image of the sample 5 with soft X-rays through a display (not shown). Further, since the objective lens 6 is of a reflection type, a sufficiently good imaging performance can be obtained as compared with a diffraction type such as a zone plate. Here, the X-ray source 1 is turned off while the vacuum chambers 3 and 9 are kept evacuated, and the visible light source is turned off.
By turning on the prism 11, inserting the prisms 14 and 15 into the optical path, and opening the shutters 13 and 17, the sample 5 can be observed again by visible light, and at the same time, the position of the sample 5 can be finely adjusted. .

In this embodiment, since the condenser lens 2 and the objective lens 6 have the same structure, even if the position of the visible light source 11 and the position of the eye are exchanged and the position of the window 12 and the position of the eyepiece 16 are exchanged, the objective lens 6 And the condenser lens 2 act as a condenser lens and an objective lens, respectively, so that the same effect is obtained.

Also, since the condenser lens 2 does not have to have the imaging performance as good as the objective lens 6, the Walter optical system 18 as shown in FIG. 2 (where F ₁ and F ₂ are the focal positions of the rotating hyperboloid) , F ₂ and F ₃ are the focal positions of the spheroid.) Alternatively, an annular optical system 19 constituted by a part of the spheroid as shown in FIG. 3 may be used. In these cases, the sample side numerical aperture is generally made equal to that of the objective lens 6 in order to effectively use the light amount.

Further, a CCD camera may be attached to a lens barrel holding the eyepiece 16, and an image may be detected by the CCD.

Also, instead of the prisms 14 and 15, a mirror 20 that can rotate around a fulcrum as shown in FIG. 4A or a mirror 20 that can be moved in the direction of an arrow as shown in FIG. The optical path of visible light may be changed using the mirror 21.

Further, the material of the windows 4 and 10 may be any material that can transmit both soft X-rays and visible light and can be a partition of a vacuum vessel.
A polyimide thin film or the like can also be used.

FIG. 5 shows a main part of the second embodiment. This is because the objective lens 6 composed of a Schwarzschild optical system alone has insufficient aberration correction in the case of visible light. In the optical path from 5 to the image formation position of the objective lens 6, a visible light correction lens 22 which can be inserted and removed is provided.

FIG. 6 shows a main part of the third embodiment, in which both the condenser lens 2 and the objective lens 6 in the first embodiment are different from the optical X-ray lens 23, which is another optical system, and the visible light. The soft X-ray lens 23 is a Schwarzschild optical system for reflecting and imaging soft X-rays having a wavelength in a predetermined band, and is incorporated in the central opening of the visible light lens 24. It consists of However, the soft X-ray lens 23
And the focal position of the visible light lens 24 are equal.

FIGS. 7 (A) and 7 (B) show a main part of the fourth embodiment and a visible light lens thereof, respectively, in which the condenser lens 2 and the objective lens 6 in the first embodiment are both different. A soft X-ray lens 25 and a visible light lens 26, each of which is a Walter optical system for reflecting and imaging soft X-rays having a wavelength in a predetermined band. A visible light lens 26 composed of a Fresnel zone plate for enlarging and forming an image of visible light of a predetermined wavelength as shown in FIG. 7B is disposed at the center. The line lens 25 also serves as a soft X-ray shielding plate. However, the focal positions of the soft X-ray lens 25 and the visible light lens 26 are equal.

FIG. 8 shows a main part of the fifth embodiment, in which both the condenser lens 2 and the objective lens 6 in the first embodiment are different from the soft X-ray lens 2 which is another optical system and the visible light. A soft X-ray lens 27 is a Walter optical system for reflecting and imaging soft X-rays having a wavelength in a predetermined band, and concentrically reflecting and imaging visible light having a predetermined wavelength. Visible light lens with Schwarzschild optical system
The convex mirror of the visible light lens 28 also plays a role as a soft X-ray shielding plate of the soft X-ray lens 27. However, soft X-ray lens 27 and visible light lens
28 focal positions are equal.

In each of the first to fifth embodiments, observation using visible light and observation using soft X-ray are performed separately. However, if the following configuration is used, observation using visible light and soft X-ray is performed. Simultaneous observation is also possible. That is, in FIG.
Instead of 14 and 15, a soft X-ray filter that transmits soft X-rays such as a Be thin film but reflects visible light may be obliquely arranged on the optical path. Then, the optical path of the visible light is bent by these soft X-ray filters, and an image is formed on a light receiving surface of a visible light detector such as a CCD camera attached to a lens barrel holding the eyepiece 16, for example. The soft X-rays pass through these soft X-ray filters and form an image on the light receiving surface of the soft X-ray detector 7. However, in this case, there is no need to provide the soft X-ray filter 8.

〔The invention's effect〕

As described above, the X-ray microscope according to the present invention has a practically important advantage that operability is improved, observation by both visible light and soft X-ray is possible, and sufficient imaging performance is obtained. ing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the X-ray microscope according to the present invention, FIGS. 2 to 4 are views showing a main part of each modification of the first embodiment, and FIGS. It is a figure which shows the principal part of 2nd thru | or 5th Example, respectively. 1 X-ray source, 2 condenser lens, 3, 9 vacuum container, 4, 10, 12 window, 5 sample, 6 objective lens, 7 soft X-ray detector, 8 Soft X-ray filter, 11
… Visible light source, 13,17 …… Shutter, 14,15 …… Prism, 16 …… Eyepiece, 18 …… Walter optical system, 19…
... Optical system, 20,21 ... Mirror, 22 ... Correction lens, 23,25,27
…… Soft X-ray lens, 24,26,28 …… Visible light lens.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiaki Horikawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (56) References JP-A-2-16498 (JP, A) JP-A 2-22600 (JP, A) JP-A-3-207000 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21K 7/00 G21K 5/00 B02B 21/00

Claims (2)

(57) [Claims] 1. An X-ray microscope comprising: a condenser lens for irradiating an X-ray emitted from an X-ray source onto an observation target; and a reflection type objective lens for focusing X-rays from the observation target at a predetermined position. In, a visible light source, illumination means for guiding light from the visible light source along substantially the same optical axis as the X-rays and irradiating the observation target, and light from the observation target at a predetermined position An objective lens for visible light to be focused, wherein the objective lens for visible light is the reflective objective lens, and a correction for visible light that can be inserted into and removed from an optical path from the object to be observed to the predetermined position. An X-ray microscope comprising a lens. 2. An X-ray microscope comprising: a condenser lens for irradiating an X-ray emitted from an X-ray source onto an observation target; and a reflective objective lens for converging the X-ray from the observation target to a predetermined position. In, a visible light source, illumination means for guiding light from the visible light source along substantially the same optical axis as the X-rays and irradiating the observation target, and light from the observation target at a predetermined position An X-ray microscope comprising: a visible light objective lens to be focused; and wherein the visible light objective lens and the reflective objective lens are different optical systems.