JPH05273398A - Soft x-ray microscope - Google Patents

Abstract

PURPOSE:To remove visible light and to selectively detect only soft X-rays. CONSTITUTION:Light sources 1, 3 emitting light including soft X-rays and visible light, an imaging optical system 8 and a detector 22 sensitive to soft X-rays and visible light are provided, and a filter 21 transmitting visible light and shielding soft X-rays is disposed in an optical-path capably of inserting and drawing. A signal detected according as the filter 21 is inserted or not is image processed, and a microimage by only soft X-rays is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a soft X-ray microscope.

[0002]

2. Description of the Related Art In recent years, research and development of X-ray light sources and X-ray optical elements have been started.
The development of X-ray microscope is one of the applied systems.
It has been put to practical use. Figure 3 shows damage to living cells
Configuration of conventional soft X-ray microscope using soft X-rays
Is shown. In the figure, 1 emits YAG laser light
Laser light source, 2 is a condenser lens, 3 is placed in a vacuum
To focus the YAG laser light on its surface.
A metal target that outputs X-rays by converting the focused part into plasma
Target, 4 is UV light cut consisting of B (boron) thin film
Filter, 5 is a grazing incidence type condenser lens, and 6 is
Si with water₃N _FourPlaced in a sealed manner by the thin film 7
Biological sample, 8 is a Schwartz coated with a multilayer film
Objective lens of sild type optical system, 9 is MCP (microchip
This is a detector using a channel plate). Such a configuration
At the surface of the metal target 3 turned into plasma
Emits X-rays in a wide wavelength range including visible and soft X-ray regions.
This X-ray is filtered by the filter 4, and the ultraviolet light is blocked.
After being processed, the biological sample is taken by the condenser lens 5.
It is focused on 6. Soft X-ray transmitted through biological sample 6
Is magnified by the objective lens 8 and imaged on the detector 9.
By visualizing the detection signal of the detector 9,
The transmission microscopic image of is obtained.

By the way, the detector 9 is an MCP.
Besides, imaging plate, semiconductor detector, CCD
Although an image sensor or the like can be used, the MCP and the imaging plate are not easy to handle, and when these are used, there is a drawback that the device structure becomes complicated and large. In addition, MCP has excellent detection wavelength characteristics, and soft X
Although it has low sensitivity to light other than the linear region, it is expensive and its spatial resolution is constrained by the thickness of the microchannel forming the MCP (at least about 12 μm).
Although the imaging plates have excellent spatial resolution, they have the drawback of lacking real-time signal detection.

On the other hand, semiconductor detectors and CCD image sensors have the advantage of being inexpensive and easy to handle. Therefore, research and development of soft X-ray image sensors have been carried out in order to enhance detection sensitivity, and recently, A soft X-ray image sensor having practical sensitivity and conversion efficiency has been proposed. FIG. 4 shows a cross section of one pixel of the soft X-ray image sensor. This sensor is a hybrid type image sensor using an AMI (internal amplification type solid-state imaging device), and in the figure, 11 is a diode D formed by providing an n ⁺ type region on the surface of a p type substrate. A plurality of stacked pixel electrodes, 12 is a photoelectric conversion layer formed on the pixel electrode 11, 13 is a surface electrode layer formed on the photoelectric conversion layer 12,
14 is an incident soft X-ray. Thus, the photoelectric conversion layer 12
Since is only covered with the thin surface electrode layer 13, the soft X-rays 14 incident on the sensor reach the photoelectric conversion layer 12 without being attenuated, and the soft X-rays can be detected with high sensitivity. Further, FIG. 5 shows the quantum efficiency of the Si diode and the GaAsP-Au Schottky diode among the semiconductors that can be used as the photoelectric conversion layer 12 (Proc.S.
PIE 733, p.481, 1986), as is clear from the figure, the quantum efficiency of these semiconductors for soft X-rays is close to 100 percent. Therefore, in addition to the sensor structure described above, the photoelectric conversion layer 12 is formed by using these semiconductors,
It is possible to dramatically improve the sensitivity. With such a soft X-ray image sensor, a resolution of up to about 10 μm per pixel can be obtained, and it is also excellent in terms of spatial resolution.

[0005]

However, in the above soft X-ray image sensor, the photoelectric conversion layer 12 has Si, GaAsP.
Since such a semiconductor is used, the photoelectric conversion layer 12 has sensitivity in a wide wavelength range from the visible region to the soft X-ray region,
There is a drawback that the detection wavelength characteristic for a line is inferior. In this case, the ultraviolet light can be cut by selecting the material of the surface electrode layer 13, but the visible light cannot be sufficiently cut by the surface electrode layer 13, and a part of the visible light overlaps the incident soft X-rays 14 so that the photoelectric conversion layer is formed. Reach 12 and cause noise in the detected signal. In the configuration of the soft X-ray microscope described above, since the X-rays output from the metal target 3 are white light including visible light and ultraviolet light, when reflected by the objective lens 8, metal reflected in addition to the soft X-rays. Visible light or ultraviolet light is imaged on the detector 9. Therefore, the soft X-ray microscope having such a configuration can
When using a line image sensor, it is necessary to remove unnecessary light with a spectroscope or the like. However, this makes it impossible to take advantage of the merit of using the soft X-ray image sensor that the device becomes complicated and large and is easy to handle.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to remove unnecessary visible light and selectively detect only soft X-rays. It is to provide a soft X-ray microscope capable of performing the same.

[0007]

A soft X-ray microscope according to the present invention comprises a light source which emits light including soft X-rays and visible light, and an object irradiated with the light emitted from the light source. An image forming optical system for forming an image and a detector having sensitivity to the soft X-rays and the visible light for receiving the image formed by the image forming optical system are provided, and the visible light is transmitted and the soft X-rays are transmitted. A filter for blocking is provided so that it can be inserted into and removed from the optical path.

Then, the difference between the first signal obtained from the detector when the filter is inserted in the optical path and the second signal obtained from the detector when the filter is moved out of the optical path is calculated. A signal processing means for extracting is provided, and the signal processing means is adapted to form a differential image representing an object.

[0009]

With the above construction, when the filter is inserted in the optical path, the object image by visible light is used as the first signal, and when the filter is moved out of the optical path, the soft X signal is used as the second signal.
An object image is obtained by superimposing rays and visible light, in other words, soft X-rays containing visible light noise. Therefore, if a difference image is formed by extracting the difference between the two signals, it is possible to obtain a transmission microscopic image using only pure soft X-rays from which visible light noise has been removed.

[0010]

Embodiments Embodiments will be described with reference to FIGS.
In the figure, the same members as those in the conventional example shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. FIG. 1 shows the configuration of the soft X-ray microscope of this embodiment. In the figure, 21 is a filter made of optical glass that transmits visible light and blocks soft X-rays, and 22 is a detector using a soft X-ray image sensor using the AMI. The filter 21 has an optical axis O
It is arranged so as to be movable in the vertical direction, and when it is inserted into the optical path, it moves to the solid line position, and when it is moved out of the optical path, it moves to the broken line position. The arrow a indicates the moving direction of the filter 21. Detector 22 is soft X
Since a line image sensor is used, ultraviolet light is cut by the surface electrode layer of the sensor, and the surface electrode layer is made of a metal such as Al so that the incident soft X-rays are not attenuated. In addition, a lot of visible light can be cut.

FIG. 2 is a processing block diagram of the image signal processing unit of this embodiment. In the figure, 23 and 24 are frame memory units for temporarily storing the image signals detected by the detector 22, and 25 is each pixel corresponding to the image signals stored in the frame memory units 23 and 24. An arithmetic processing unit that extracts the difference between the signals to form a differential image signal, and a display unit 26 that displays the differential image signal formed by the arithmetic processing unit 25. Each of these processing units is controlled by a computer (not shown), and operates in synchronization with the YAG laser light output timing of the laser light source 1 and the arrangement state of the filter 21.

In this structure, first, the filter 21
Is inserted into the optical path to cause the metal target 3 to output an X-ray, and in this state, the detector 22 performs signal detection. The detected signal is used as the image signal Fv in the frame memory unit 23.
To store. Next, after the filter 21 is moved out of the optical path, the X-ray is output again and the detector 22 performs signal detection, and the signal detected in this state is stored in the frame memory unit 24 as the image signal Fx ′. ..

Here, the visible light transmission microscopic image stored in the frame memory unit 23 as the image signal Fv is a background signal for the X-ray transmission microscopic image stored in the frame memory unit 24 as the image signal Fx ′. is there. Therefore, in the arithmetic processing unit 25, the difference (Fx ') between the image signal Fv and the image signal Fx' at each corresponding pixel.
-Fv) is extracted to form the differential image signal Fx, a visible transmission light microscopic image obtained by pure soft X-rays alone is obtained. A transmission microscopic image of soft X-rays can be observed by contrast.

In this embodiment, the filter 21 is arranged between the objective lens 8 and the detector 22.
The position is not limited to this, and it may be arranged at an appropriate position between the light source 1 and the detector 22 depending on the conditions of the device structure and the optical elements used. Further, the detector 22 is not limited to the soft X-ray image sensor using AMI, and other soft X-ray detectors having sensitivity in the visible region can also obtain the same effect as the present invention.

[0015]

As described above, in the soft X-ray microscope according to the present invention, the filter for blocking the soft X-ray is arranged in the optical path so that it can be inserted / removed, and the detection signal corresponding to the insertion / removal state of the filter is processed. By doing so, there is no noise due to visible light, soft X
It is possible to selectively obtain a transmission microscopic image by only the lines.
Therefore, the soft X having high sensitivity to visible light and soft X-rays
The line detector can be effectively used, and the filter for blocking the soft X-rays can be arranged at an appropriate position in the optical path, which is effective for downsizing the device and reducing the cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a soft X-ray microscope according to the present invention.

FIG. 2 is a processing block diagram of an image signal processing unit of the soft X-ray microscope according to the present invention.

FIG. 3 is a configuration diagram of a conventional soft X-ray microscope.

FIG. 4 is a sectional view of one pixel of a soft X-ray image sensor.

FIG. 5 is a diagram showing quantum efficiency of a semiconductor.

[Explanation of Codes] 1 ... Laser light source 2 ... Condensing lens 3 ... Metal target 4, 21 ... Filter 5 ... Condenser lens 6 ... Biological sample 8 ... Objective lens 9 , 22 ... Detector 23, 24 ... Frame memory section 25 ... Arithmetic processing section 26 ... Display section

Continued Front Page (72) Inventor Shoichiro Mochimaru 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (2)

[Claims] 1. An object is irradiated with radiation from a light source including soft X-rays and visible light, and light from the object is soft X-rays through an imaging optical system.
In a soft X-ray microscope that obtains an object image by focusing on a detector that is sensitive to rays and visible light, a filter that transmits visible light and blocks soft X-rays can be inserted and removed in the optical path. A soft X-ray microscope, which is provided in the. 2. A difference between a first signal obtained from the detector when the filter is inserted in the optical path and a second signal obtained from the detector when the filter is moved out of the optical path. The soft X-ray microscope according to claim 1, further comprising signal processing means for extracting.