JPH0616394B2 - Electron microscope image recording / reproducing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for recording / reproducing an electron microscope image, and more specifically, for recording an electron microscope image with high sensitivity and for processing various images by an electric signal. The present invention relates to a recording / reproducing method of an electron microscope image adapted to be reproduced.

(Technical Background of the Invention and Prior Art) Conventionally, an electron microscope has been known in which an electron beam transmitted through a sample is refracted by an electric field or a magnetic field to obtain an enlarged image of the sample. As is well known, in this electron microscope, the electron beam transmitted through the sample forms a diffraction pattern of the sample on the back focal plane of the objective lens, and the diffraction lines interfere again to form a magnified image of the sample. Has become.
Therefore, if the magnified image is projected by the projection lens, the magnified image (scattered image) of the sample is observed, and if the back focal plane is projected, the magnified diffraction pattern of the sample is observed. If an intermediate lens is arranged between the objective lens and the projection lens, the above-mentioned magnified image (scattered image) or diffraction pattern can be optionally obtained by adjusting the focal length of this intermediate lens.

In order to observe the magnified image or diffraction pattern (hereinafter collectively referred to as a transmission electron beam image) formed as described above, conventionally, a photographic film is placed on the image plane of the projection lens to transmit a transmission electron beam. The image is exposed or an image intensifier is arranged to amplify and project the transmission electron beam image. However, photographic film has the disadvantage of low sensitivity to electron beams and troublesome development processing. On the other hand, when an image intensifier is used, the sharpness of the image is low and the image tends to be distorted. There is.

Further, for the transmission electron beam image as described above, gradation processing, frequency enhancement processing, density processing, for the purpose of making the image easy to see,
Image processing such as subtraction processing, addition processing, three-dimensional image reconstruction by Fourier analysis method, image analysis for binarization of the image and particle size measurement, and further diffraction pattern processing (crystal information analysis, (Lattice constant, transition, clarification of lattice defects, etc.) are often performed, but in such a case, conventionally, a microscope image obtained by developing a photographic film is read by a microphotometer and converted into an electric signal. The complicated work of converting the electric signal and performing A / D conversion of the electric signal and then processing the electric signal has been performed.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is capable of recording and reproducing an electron microscope image with high sensitivity and high image quality.
Moreover, it is an object of the present invention to provide an electron microscope image recording / reproducing method by which an electric signal for carrying a microscope can be directly obtained so that various kinds of processing can be facilitated.

(Structure of the Invention) An electron microscope image recording / reproducing method of the present invention is to maintain the above-mentioned vacuum state after accumulating and recording the electron beam passing through the sample in a vacuum state on a stimulable phosphor sheet for accumulating electron beam energy. As it is, the accumulative phosphor sheet is scanned with excitation light to release the accumulated energy as light, and the emitted light is photoelectrically detected to reproduce the transmitted electron beam image of the sample.
The focusing condition and / or the visual field range of the electron microscope are changed little by little, and the accumulated recording is performed a plurality of times, and then the emitted light is detected to reproduce a plurality of focusing and / or visual fields from the electric signal obtained thereby. It is characterized by observing the search image and selecting a preferable condition out of the focus condition and / or a desired range out of the visual field range.

Specific examples of the stimulable phosphor sheet include, for example, JP-A-55-12429, JP-A-55-116340, and JP-A-55-116340.
5-163472, 56-11395, 56-
The stimulable phosphor sheet disclosed in Japanese Patent No. 104645 or the like can be particularly preferably used. That is, when a certain kind of fluorescent material is irradiated with radiation such as an electron beam, a part of the energy of this radiation is accumulated in the fluorescent material, and then the fluorescent material is irradiated with excitation light such as visible light, The fluorescent substance exhibits fluorescence (stimulated luminescence) according to the stored energy. A phosphor showing such a property is referred to as a stimulable phosphor, and the stimulable phosphor sheet is a sheet-shaped recording material made of the stimulable phosphor, which is generally a support and a support. And a stimulable phosphor layer laminated on a support. The stimulable phosphor layer is formed by dispersing the stimulable phosphor in a suitable binder. When the stimulable phosphor layer is self-supporting,
As such it can be a stimulable phosphor sheet.

When the above-mentioned stimulable phosphor sheet is placed on the image plane of an electron microscope and an electron microscope image by a transmission electron beam is accumulated and recorded on the harmful sheet, this sheet is scanned with excitation light such as visible light to cause fluorescence. If light is generated and the fluorescence is read photoelectrically, an electric signal corresponding to the transmitted electron beam image can be obtained. By using the electrical image signal thus obtained, it is possible to display an electron microscope image on a display such as a CRT, or to permanently record it as a hard copy, and further, to temporarily record the image signal on a magnetic tape. It can also be stored in a recording medium such as a magnetic disk.

In the electron microscope image recording / reproducing method of the present invention, since the electron microscope image is accumulated and recorded on the accumulative phosphor sheet, it becomes possible to record the electron microscope image with high sensitivity, and therefore the electron microscope image is recorded. The amount of electron beam exposure can be reduced,
Damage to the sample can be reduced. Further, in the method of the present invention, it becomes extremely easy to perform image processing such as gradation processing and frequency enhancement processing on the electron microscope image, and also the processing of the diffraction pattern as described above, the reconstruction of the three-dimensional image, the image Image analysis such as binarization can be performed much easier and faster than before by inputting the electric signal to the computer.

In the method of the present invention, as described above, the image for focusing and / or visual field searching is also reproduced by using the stimulable phosphor sheet. Therefore, when focusing and / or visual field searching, The electron dose applied to the sample can be reduced.

Examples of the stimulable phosphor used in the stimulable phosphor sheet used in the present invention include SrS: Ce, Sm and SrS: described in US Pat. No. 3,859,527. Eu, Sm, Th
A phosphor represented by a composition formula such as O ₂ : Er and La ₂ O ₂ S: Eu, Sm, and Zn described in JP-A-55-12142.
S: Cu, Pb, BaO.xAl ₂ O ₃ : Eu [where 0.8 ≦ x ≦ 10] and M ²⁺ O.xSi
O ₂ : A [where M ²⁺ is Mg, Ca, Sr, Zn, C
d, or Ba, A is Ce, Tb, Eu, Tm,
Pb, Tl, Bi, or Mn, and x is 0.5 ≦
x ≦ 2.5] and a phosphor represented by a composition formula such as that described in JP-A-55-12143 (Ba).
_{1-xy, Mg x, Ca} y) FX: aEu 2+ [ However, X
Is at least one of Cl and Br, x and y are 0 <x + y ≦ 0.6, and xy ≠ 0, and a
Is 10 ⁻⁶ ≦ a ≦ 5 × 10 ⁻² ], the phosphor represented by the composition formula: LnO described in JP-A-55-12144.
X: xA [where Ln is La, Y, Gd, and Lu]
At least one of X, Cl is at least one of Br and A, at least one of Ce and Tb is A, and X is 0 <x <0.1. The phosphors represented are described in JP-A-55-12145 (Ba
_1-x , M ^II _x ] FX: yA [where M ^II is Mg, Ca,
At least one of Sr, Zn, and Cd, X is at least one of Cl, Br, and I, and A is E
u, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Y
at least one of b and Er, and x is
0 ≦ x ≦ 0.6, y is 0 ≦ y ≦ 0.2], a phosphor represented by the composition formula: M ^II described in JP-A-55-160078.
FX xA: yLn [However, M ^II is Ba, Ca, S
at least one of r, Mg, Zn, and Cd,
A is BeO, MgO, CaO, SrO, BaO, Zn
O, Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ ,
_{SiO 2, TlO 2, ZrO 2} , GeO 2, SnO 2,
At least one of Nb ₂ O ₅ , Ta ₂ O ₅ , and ThO ₂ , and Ln is Eu, Tb, Ce, Tm, Dy, P.
At least one of r, Ho, Nd, Yb, Er, Sm, and Gd, X is at least one of Cl, Br, and I, and x and y are each 5 × 10 5.
^-5 ≤ x ≤ 0.5 and 0 <y ≤ 0.2], described in JP-A-56-116777 (B).
a _1-x , M ^II _x ] F ₂ · aBaX ₂ : yEu, zA [wherein M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine, and iodine. , At least one of zirconium and scandium, and a, x, y, and z are 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y, respectively. ≤
2 × 10 ⁻¹ , and 0 <z ≦ 10 ⁻² ], the phosphor represented by the composition formula, which is described in JP-A-57-23673 (Ba).
_1-x , M ^II _x ) F ₂ · aBaX ₂ : yEu, zB [wherein M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine, or iodine. At least one of which a, x, y, and z are each 0.5
≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦ 2 × 1
0 ^-1 , and 0 <z ≤ 10 ^-1 ], the phosphor represented by the composition formula, which is described in JP-A-57-23675 (Ba).
_1-x , M ^II _x ) F ₂ · aBaX ₂ : yEu, zA [wherein M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine, or iodine. At least one of them, A is at least one of arsenic and silicon, and a, x, y, and z are each 0.5 ≦ a ≦.
1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦ 2 × 10 ⁻¹ , and 0 <z ≦ 5 × 10 ⁻¹ ]. Ba described in 206678
_1-x M _{x / 2} L _{x / 2} FX: yEu ²⁺ [where M is Li, N
a represents at least one alkali metal selected from the group consisting of K, Rb, and Cs; L represents Sc, Y,
La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, D
y, Ho, Er, Tm, Yb, Lu, Al, Ga, I
n, and at least one trivalent metal selected from the group consisting of Tl; X represents at least one halogen selected from the group consisting of Cl, Br, and I; and x represents 10 ^-2 ≤ x ≦ 0.5, y is 0 <y ≦
0.1) The phosphor represented by the composition formula, BaF described in JP-A-59-27980.
X · xA: yEu ²⁺ [wherein X is at least one halogen selected from the group consisting of Cl, Br, and I; A is a calcined product of a tetrafluoroboric acid compound; and x is 10 ⁻⁶ ≦ x ≦ 0.1, y is 0 <y ≦
A phosphor represented by a composition formula of 0.1], and BaF described in JP-A-59-47289.
X · xA: yEu ²⁺ [wherein X is at least one halogen selected from the group consisting of Cl, Br, and I; A is hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; It is a calcined product of at least one compound selected from the group of hexafluoro compounds consisting of salts of monovalent or divalent metals; and x is 10 ⁻⁶ ≦ x ≦ 0.1 and y is 0 <y ≦ 0.1. And a BaF described in JP-A-59-56479.
X · xNaX ′: aEu ²⁺ [where X and X ′ are
At least one of Cl, Br, and I, and x and a are 0 <x ≦ 2 and 0 <, respectively.
a ≦ 0.2], a phosphor represented by the composition formula: M ^II F described in JP-A-59-56480.
X · xNaX ′: yEu ²⁺ : zA [where M ^II is B
at least one alkaline earth metal selected from the group consisting of a, Sr, and Ca; X and X ′ are each at least one halogen selected from the group consisting of Cl, Br, and I; A is , V, Cr, M
at least one transition metal selected from n, Fe, Co, and Ni; and x is 0 <x ≦ 2 and y is 0.
<Y ≦ 0.2, and z is 0 <z ≦ 10 ⁻² ], and a phosphor represented by the composition formula: M ^II FX described in Japanese Patent Application Laid-Open No. 59-75200 by the present applicant.・ AM ^I X '・ bM' ^III X " ₂・ C
M ^III X ″ ″ ₃ · xA: yEu ²⁺ [where M ^II is Ba,
Is at least one alkaline earth metal selected from the group consisting of Sr and Ca; M ^I is Li, Na, K,
Rb, and at least one alkali metal selected from the group consisting of Cs, M ^'II is at least one trivalent metal selected from the group consisting of Be and Mg;
M ^III is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; X is at least one selected from the group consisting of Cl, Br, and I Is halogen; X ′,
X ″ and X ″ ″ are at least one halogen selected from the group consisting of F, Cl, Br, and I;
Then, a is 0 ≦ a ≦ 2, b is 0 ≦ b ≦ 10 ⁻² , c is 0 ≦ c ≦ 10 ⁻² , and a + b + c ≦ 10 ⁻⁶ ; x is 0 <x ≦ 0.5, y is 0 <y ≦ 0.2], a phosphor represented by the composition formula: M ^II X ₂ · aM ^II X ′ ₂ : aEu ²⁺ [described in Japanese Patent Application No. 58-193161. Provided that M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X
And X ′ is at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X ′; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0. , X is a numerical value in the range of 0 <x ≦ 0.2], and the like.

However, the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphor, and when irradiated with excitation light after being irradiated with radiation, it is a phosphor showing stimulable luminescence. It may be any one.

These phosphor sheets may have a protective layer or a light-reflecting or light-absorbing undercoat layer, and the phosphor layer is disclosed in JP-A-55-163500. It may be colored with a pigment or a dye.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic view of an electron microscope image recording / reproducing apparatus for carrying out the method according to the embodiment of the present invention.

This electron microscope image recording / reproducing apparatus is a normal electron microscope 1
A stimulable phosphor as a two-dimensional sensor, which is arranged below the mirror body portion 1a of the same so as to belong to the same vacuum system as the image plane of the electron beam image at least when the electron microscope image is exposed (when recording) A recording / reading unit 1b including a sheet 10, an excitation unit that scans the sheet 10 with excitation light while keeping it in a vacuum state, and a detection unit that photoelectrically detects stimulated emission light emitted from the sheet 10 is provided. It will be. A part of the mirror body portion 1a and the recording / reading portion 1b (inside the hatched frame in the drawing) is kept in a vacuum state by a well-known means during the operation of the electron microscope.

The mirror portion 1a includes an electron gun 3 for emitting an electron beam 2 having a uniform velocity, at least one focusing lens 4 including a magnetic lens and an electrostatic lens for narrowing the electron beam 2 on the sample surface, and a sample stand. 5, an objective lens 6 similar to the focusing lens 4, and a projection lens 7. The electron beam 2 transmitted through the sample 8 placed on the sample table 5 is refracted by the objective lens 6 to form an enlarged scattered image 8a of the sample 8. This enlarged scattered image 8a is image-projected by the projection lens 7 on the image plane 9 (8b in the figure).

On the other hand, the recording / reading unit 1b has a cylindrical driving roller 101.
Similarly to the above, the accumulative phosphor sheet 10 of the endless belt hung on the cylindrical driven roller 102, the excitation light source 11 such as a He-Ne laser, a semiconductor laser and the excitation light source 1
1. Excitation means including an optical deflector 12 such as a galvanometer mirror that deflects the excitation light 11a emitted from the sheet 1 in the width direction of the sheet 10, and the stimulated emission light emitted from the sheet 10 by the excitation light beam 11a is condensed. Light collector 14
Is provided on the exit end face of the detector, and has a detection unit composed of a photoelectric converter 15 such as a photomultiplier that receives the stimulated emission light through a filter for removing the excitation light, photoelectrically converts the light into an electric signal. The stimulable phosphor sheet 10 is formed by laminating the above-mentioned stimulable phosphor layer on the surface of a highly flexible endless belt-like support. The sheet 10 is hung between a driving roller 101 and a driven roller 102, and is rotatable in the direction of arrow A by the driving roller 101 rotated by a driving device (not shown).

In the present embodiment, the endless belt-shaped stimulable phosphor belt 10, the driving roller 101 for moving the belt, the driven roller 102, the condenser 14, and the photoelectric converter 15 are arranged in a vacuum system. If the optical body 14 is arranged so that its end part penetrates the wall of the optical body and goes out of the vacuum system, the photoelectric converter 1
5 can be installed outside the vacuum system.

When a shutter (not shown) provided between the mirror portion 1a and the recording / reading portion 1b is opened, a portion of the stimulable phosphor sheet 10 located at the recording position (that is, the image plane 9) is
Electron beam energy carrying the enlarged scattered image 8b of the sample is accumulated. This part of the sheet 10 is then driven by the drive roller 1
The rotation of 01 moves it to the outside of the recording location and sends the unexposed portion to the recording location.

Then, when a new image is recorded on this unexposed area,
The electron microscope operator slightly operates the focusing knob 30 of the electron microscope to make the focus state of the enlarged scattered image 8b newly recorded on the sheet 10 slightly different from that in the previous recording. As is well known, the focusing knob 30 changes the electric field of the objective lens 6 to change its focal length. Thus sheet 1
A plurality of magnified scattered images 8b whose focus is slightly changed to 0 are recorded. The electron microscope operator records or stores how the focusing knob 30 is set (focus condition) in each image recording.

Further, the accumulated recording on the sheet 10 a plurality of times is
It is not necessary to cover the entire image plane. For example, by limiting the open area of the shutter,
The electron beam irradiation area may be narrowed, which reduces the reading area for setting the focus condition, thus shortening the operation time.

Next, the portion of the sheet 10 on which the accumulated recording is performed a plurality of times is moved to the reading position by the rotation of the driving roller 101. In the present embodiment, the excitation light beam 11a deflected as described above outside the vacuum system is made incident on the sheet 10 through the translucent wall portion 19a such as lead glass, and the beam 11a causes the sheet 10 to have its width. While the main scanning is performed in the direction, the sheet 10 is sub-scanned by moving the sheet 10 in the direction perpendicular to the width direction (direction of arrow A) by the driving roller 101. The stimulated emission light generated from the stimulable phosphor sheet 10 by this excitation light irradiation enters the light collector 14 from the incident end surface of the light collector 14 (the end surface facing the sheet 10), The light proceeds by total reflection, is received by the photoelectric converter 15 connected to the exit end face of the light collector 14, and the stimulated emission light amount is photoelectrically read.

After the above reading is completed, the driving roller 101 is driven to send the image recorded portion of the stimulable phosphor sheet 10 to the erasing zone 20. In the erasing zone 20, the erasing light emitted from the erasing light source 21 of the fluorescent lamp provided outside the vacuum system is applied to the sheet 10 through the translucent wall member 19b. The erasing light source 21 irradiates the stimulable phosphor sheet 10 with light included in the excitation wavelength region of the luminescent material, whereby the stimulable phosphor sheet 10 is accumulated in the luminescent layer of the stimulable phosphor sheet 10. The residual image and the noise due to radioactive elements such as ²²⁶ Ra contained as an impurity in the phosphor of the sheet 10, for example, Japanese Patent Laid-Open No. 56-1.
Tungsten lamp as shown in 1392,
A halogen lamp, an infrared lamp, a xenon flash lamp, a laser light source, or the like can be arbitrarily selected and used.

The image recording portion of the sheet 10 from which afterimages and noises have been erased in this way is sent to the recording portion, where the enlarged scattered image 8b is again accumulated and recorded on the sheet 10 as described above. If the sheet 10 is sufficiently long, when the sheet 10 is fed by a predetermined length for image reading, the sheet 10
Since the printable portion is sent to the printing portion, the next image recording may be performed on this portion, and therefore it is not necessary to make one round of the sheet 10 for each image recording.

The electric signal obtained by reading the stimulated emission light by the photoelectric converter 15 is transmitted to the image processing circuit 16, subjected to necessary image processing, and then sent to the image reproducing apparatus. This playback device may be a display 17 such as a CRT,
Further, as shown in FIG. 3, a recording device 50 for performing optical scanning recording on a photosensitive film may be used. Hereinafter, a case where an image is reproduced by the optical scanning recording device 50 of FIG. 3 will be described.

The photosensitive film 35 is moved in the sub-scanning direction shown by the arrow Y in FIG.
Is scanned on the photosensitive film 35 in the direction of the arrow X, and the laser beam 31 is modulated by the A / O modulator 33 based on the image signal from the signal supply circuit 32. To form. If the signal output from the image processing circuit 16 is used as the modulation image signal, the enlarged scattered image 8b accumulated and recorded on the sheet 10 is reproduced on the photosensitive film 35.

In the method of the present invention, before reproducing the final output image of the enlarged scattered image 8b on the photosensitive film 35, a plurality of focusing images of the enlarged scattered image 8b are created using the photosensitive film 35. Alternatively, a plurality of focusing images may be arranged and output on one photosensitive film.

In this way, a plurality of magnified scattered images 8b having slightly different focus states are reproduced. The electron microscope operator compares and observes the plurality of focusing images, and selects the image that is most accurately in focus. When this image displays the entire enlarged scattered image 8b,
This can also be the final output image. However, since the focusing image is preferably obtained by recording a part of the magnified scattered image 8b, the magnified scattered image 8b is obtained in order to obtain the final output image after selecting the image that is most accurately in focus. The image is read on the sheet 10, the image is read, and then the image is reproduced on the photosensitive film 35. At this time, the focusing knob 30 is set in the same manner as when the selected image was recorded. When the image recording is performed in this manner, the enlarged scattered image 8b in the final output image reproduced on the photosensitive film 35 is exactly in focus, as in the selected focusing image. The recording of the focus condition and the setting of the focus at the time of exposure of the magnified scattered image 8b for obtaining the final output image are performed by installing a recording device in the electron microscope so that the focus condition is automatically set by the operator. You may Further, the image size of this final output image is set to be larger than the size of the image forming surface 9 (that is, the storage recording area on the two-dimensional sensor), and the image is reproduced larger than the screen size on the image forming surface 9. Preferably. In order to output the enlarged agent by the image scanning recording apparatus as shown in FIG. 2, the scanning line density should be made coarser than the reading scanning line density when the image information is obtained from the stimulable phosphor sheet 10. Good. In order to obtain sufficient image information from a small-sized stimulable phosphor sheet as in the present invention, the read scan line linear density is 10 pixels / mm or more, particularly 15 pixels / mm.
The scanning line density for reproducing image recording is coarser than this, and preferably the scanning line used in the range of 5 pixels / mm to 20 pixels / mm. If a scanning line density that is coarser than the density is selected, a magnified reproduced image can be obtained without deterioration in image quality.

The final output image described above is displayed on the display 17 such as the CRT.
May be played back to, or to play later,
The signal is transferred to a recording medium 18 such as a magnetic tape or a magnetic disk.
It may be stored in.

When the focusing image is reproduced on the display 17 such as a CRT, it is preferable that a signal carrying each focusing image is temporarily stored in a magnetic disk or the like, and the signal is read from the magnetic disk to reproduce the image. By doing so, it is possible to repeatedly reproduce the focusing images in random order, and to easily compare the focusing states of the images.

Further, if a suitable light-shielding shutter or the like is provided between the recording unit and the reading unit of the enlarged scattered image 8b, it is possible to record the next image at the same time as reading the focusing image. Further, without using the endless belt-shaped accumulative phosphor sheet 10 as described above, one accumulative phosphor sheet of a predetermined size is reciprocally conveyed between the recording unit and the reading unit,
Image recording and reading may be performed alternately,
Further, such a stimulable phosphor sheet may be fixed to a conveying means such as one or a plurality of endless belts and may be reused. In these cases, a plurality of images with different focus may be divided and stored in one accumulative phosphor sheet for accumulation and recording.

Further, the image for focusing need not be output to the same size as the final output image, and the excitation light irradiation and the stimulated emission light detection are performed for a part in the image area of the final output image,
You may make it output the image of only one part. This shortens the time required to reproduce the focusing image and improves the efficiency of the focusing work. In addition, when the image for focus adjustment is reproduced, even if the image is read in a larger pixel unit than that in the reproduction of the final output image, the same effect as described above can be obtained.

Further, after reading the focusing image from the sheet 10, it is not always necessary to irradiate the sheet 10 with the erasing light as described above in order to accumulate and record the next focusing image on the sheet 10. . That is, if the reading signal of the focusing image is stored in the storage means, the sheet 1 on which the focusing image is recorded next time.
Even if a new focusing image is accumulated and recorded on the same portion of 0, only the new focusing image is extracted by performing arithmetic processing so as to subtract the read signal at the next image reading. Can be played back.

The focusing image described above can be used not only for focusing the enlarged scattered image 8b, but also for determining the visual field range of the final output image (visual field search). In the case of searching for a visual field, the reproduced image is observed and the sample 8 is moved little by little, or the position at which the electron beam 2 is irradiated on the sample surface is changed little by little, and an enlarged scattered image 8b of a desired visual field range is obtained. You can do it like this. In addition,
When searching for the field of view, it is necessary to reproduce the entire image corresponding to the image area of the final output image.

Further, if a shutter is provided between the electron gun 3 of the sample 8 of the mirror body portion 1a and the electron beam is blocked except when photographing, the sample 8 is further prevented from being damaged.

Although the embodiment of recording and reproducing the enlarged scattered image of the sample 8 by the transmitted electron beam has been described above, the present invention can also be applied to record and reproduce the diffraction pattern of the sample described above. FIG. 2 shows how the diffraction pattern 8c of the sample 8 is recorded. In this embodiment, the electron microscope 40 is provided with an intermediate lens 41 between the objective lens 6 and the projection lens 7, and the diffraction pattern 8c of the sample 8 formed on the back focal plane of the objective lens 6 is The intermediate lens 41 and the projection lens 7 focused on the back focal plane projects the image on the image plane 9 in an enlarged scale. Also in this case, if a stimulable phosphor sheet 10 as a two-dimensional sensor is arranged on the image plane 9, an enlarged image of the diffraction pattern 8c by the transmitted electron beam 2 is accumulated and recorded on the sheet 10. The accumulated and recorded diffraction pattern 8c can be read in exactly the same manner as described with reference to FIG. 1, and the read image can be displayed on the CRT or reproduced as a hard copy.

Further, in order to eliminate the influence of fluctuations in recording conditions or to obtain an electron microscope image having excellent observability, recording of a transmitted electron beam image (enlarged scattered image or enlarged diffraction pattern) accumulated and recorded on the stimulable phosphor sheet 10. The recording pattern determined by the condition, sample properties, recording method, etc. is grasped prior to the output of a visible image for sample observation, and the reading gain is adjusted to an appropriate value based on this accumulated record information. Alternatively, it is preferable to perform appropriate signal processing.
Further, it is required to determine the recording scale factor so that the resolution is optimized according to the contrast of the recording pattern in order to obtain a reproduced image with excellent observability.

As described above, as a method of grasping the stored record information of the stimulable phosphor sheet 10 prior to the output of the visible image, for example, the method shown in Japanese Patent Laid-Open No. 58-89245 can be used. That is, by using the excitation light having an energy lower than the energy of the excitation light to be irradiated in the reading operation (main reading) for obtaining a visible image for observing the sample 8, the accumulative phosphor is preliminarily preceded by the main reading. A read operation (pre-reading) for grasping the accumulated record information accumulated and recorded on the sheet 10 is performed, the accumulated record information of the sheet 10 is grasped, and then the main reading is performed, and the reading gain is adjusted based on the pre-read information. It can be adjusted appropriately, the recording scale factor can be determined, or appropriate signal processing can be performed.

Further, in order to appropriately adjust the reading gain or the recording scale factor as described above, or to perform appropriate signal processing, in addition to the above pre-reading, the above-described focusing image is displayed on the display 17 such as a CRT. When reproducing, an appropriate reading gain, recording scale factor, or signal processing condition is interactively determined in advance while observing the display 17, and when the final output image is reproduced, the previously determined reading is performed. Image reading and signal processing may be performed based on the gain, recording scale factor, or signal processing conditions.

Further, as the photoelectric reading means for photoelectrically reading the stimulated emission light emitted from the stimulable phosphor sheet 10, in addition to using the above-described photomul, a solid photoelectric conversion element such as a photoconductor or a photodiode. Can also be used (Japanese Patent Application No. 58-86226 and Japanese Patent Application No. 58-86227).
No. 58-193313 and Japanese Patent Application No. 58-2
Each specification of 19314 and JP-A-58-1218.
74 publication). In this case, a large number of solid-state photoelectric conversion elements may be configured to cover the entire surface of the sheet 10 and integrated with the sheet 10, or the sheet 10 may be integrated.
It may be arranged in the vicinity of. Further, the photoelectric reading means may be a line sensor in which a plurality of photoelectric conversion elements are linearly connected, or one solid-state photoelectric conversion element corresponding to one pixel is provided on the entire surface of the stimulable phosphor sheet 10. It may be configured to scan and move over.

As the reading excitation light source in the above case, in addition to a point light source such as a laser, a line light source such as an array in which light emitting diodes (LEDs) and semiconductor lasers are connected in a line may be used. By performing reading using such a device, it is possible to prevent the loss of stimulated emission light emitted from the stimulable phosphor sheet 10 and at the same time increase the light receiving solid angle to enhance the S / N. . Further, the obtained electric signal is not time-sequentially irradiated with the excitation light, but is time-sequentially processed by electric processing of the photodetector, so that the reading speed can be increased.

(Effects of the Invention) As described in detail above, according to the method of the present invention, the electron microscope image is accumulated and recorded on the stimulable phosphor sheet, so that the electron microscope image can be recorded with high sensitivity. Therefore, the electron beam exposure of the electron microscope can be reduced,
Damage to the sample can be reduced. Also, since the recorded image can be displayed on the CRT or the like immediately with high sensitivity, a clear monitor image can be obtained by using the reproduced image as the monitor image for focus adjustment and / or field of view search of the electron microscope. It becomes possible to perform focus adjustment and / or field-of-view search with a low electronic exposure amount, which has been impossible in the past.

Moreover, in the method of the present invention, since the electron microscope image is read as an electric signal, it becomes extremely easy to perform image processing such as gradation processing and frequency enhancement processing on the electron microscope image, and the diffraction pattern processing as described above and Image analysis such as reconstruction of a three-dimensional image and binarization of an image can be performed extremely easily and quickly by inputting the electric signal into a computer as compared with the conventional case.

Further, since the accumulative phosphor sheet for accumulating and recording electron microscope images can be reused by subjecting it to light irradiation, heating, etc., according to the present invention, when a conventional silver salt photographic system is adopted. It is possible to reproduce the electron microscope image more economically than the above. Further, in the method of the present invention, since the stimulable phosphor sheet can be reused in the vacuum system common to the electron beam image forming surface, it is not necessary to break the vacuum to replace the film unlike the conventional film method. Also, it has an effect that a large number of shootings can be continuously performed.

Further, in the method of the present invention, the focusing and / or field-of-view image of the electron microscope image is also accumulated and recorded on the stimulable phosphor sheet.
Alternatively, the electron dose applied to the sample for searching the field of view can be significantly reduced, and the effect of preventing sample damage is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic view showing an apparatus for carrying out the method of the first embodiment of the present invention, FIG. 2 is a schematic view showing a part of an electron microscope to which the method of the second embodiment of the present invention is applied, and FIG. FIG. 3 is a schematic view showing an example of an image reproducing device used in the method of the present invention. 1, 40 ... Electron microscope, 2 ... Electron beam 9 ... Image plane of electron microscope 10 ... Accumulative phosphor sheet 11 ... Excitation light source 11a ... Excitation light beam, 12 ... Optical deflector 14 ...... Condenser, 15 ...... Photoelectric converter 17 ...... Display 30 ...... Focus adjustment knob 31 ...... Laser beam, 32 ...... Signal supply circuit 33 ...... Modulator, 35 ...... Photosensitive film 50 ...... Optical scanning Recording device

Claims (4)

[Claims] 1. An electron beam transmitted through a sample is stored and recorded in a vacuum state on a stimulable phosphor sheet for accumulating electron beam energy, and then the stimulable phosphor sheet is retained while maintaining the vacuum state. In an electron microscope image recording / reproducing method in which energy accumulated by scanning with excitation light is emitted as light, and the emitted light is photoelectrically detected, the accumulation condition is gradually changed by changing the focusing condition and / or the visual field range of the electron microscope. Recording is carried out a plurality of times, then the emitted light is detected, and a plurality of focusing and / or field-of-view searching images reproduced from the electric signals obtained thereby are observed to observe preferable conditions and / or Alternatively, the electron microscope image recording / reproducing method is characterized in that a desired range is selected from the visual field range. 2. The electron microscope image recording according to claim 1, wherein the detection of the emitted light for obtaining the focusing image is performed on a part of the image area of the final output image. How to play. 3. The detection of the emitted light for obtaining the image for focusing and / or the visual field search is performed in a larger pixel unit than that for detecting the emitted light for obtaining the final output image. The electron microscope image recording / reproducing method according to claim 1 or 2. 4. Accumulation and recording of an electron beam on a stimulable phosphor sheet for obtaining a final output image by selecting a preferable condition of the focusing condition and / or a desired range of the visual field range. The electron microscope image recording / reproducing method according to claim 1, wherein the selected focusing condition and / or the visual field range is set at the time of this accumulation recording.