JPH0556617B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for recording and reproducing electron beam image information. More specifically, the present invention relates to a method for recording and reproducing electron beam image information that enables highly sensitive and highly accurate recording and reproducing of transmitted electron beam images or reflected electron beam images of a sample.

[Background of the Invention] Electron microscope devices and electron beam diffraction devices that irradiate a sample with an electron beam under vacuum to obtain a transmitted electron beam image or a reflected electron beam image have been known for some time. In an electron microscope device, an electron beam transmitted through a sample forms a diffraction pattern of the sample on the back focal plane of an objective lens, and the diffraction rays interfere again to form an enlarged image of the sample. Therefore, if the above-mentioned enlarged image is projected by the projection lens, an enlarged image (scattered image) of the sample will be observed, and if the above-mentioned back focal plane is projected, the enlarged diffraction pattern of the sample will be observed. Note that if an intermediate lens is disposed between the objective lens and the projection lens, the above-mentioned magnified image (scattered image) or diffraction pattern can be obtained at will by adjusting the focal length of this intermediate lens. In addition, in electron beam diffraction devices, one type obtains a diffraction pattern by irradiating the sample surface with an electron beam and recording the reflected diffraction rays (reflection method), and the other obtains a diffraction pattern by recording the diffraction rays that pass through the sample. (transmission method).

Generally, as a means to make the above-mentioned enlarged image or diffraction pattern (hereinafter referred to as an electron beam image) into a visible image, a photographic film is placed on the imaging plane and the electron beam image is recorded on it, or the image is A method is used in which an intensifier is arranged to amplify and project an electron beam image. However, photographic film has the drawbacks of low sensitivity to electron beams and cumbersome processing.On the other hand, when using image intensifiers, the sharpness of the image is low and distortion is likely to occur in the image. There is a problem.

Furthermore, the electron beam image recorded as described above is subjected to image processing such as gradation processing, frequency emphasis processing, density processing, subtraction processing, and addition processing, as well as Fourier analysis, for the purpose of making the image easier to see. Reconstruction of three-dimensional images by folding methods, image analysis for image binarization and particle size measurement, and processing of diffraction patterns (analysis of crystal information, clarification of lattice constants, dislocations, lattice defects, etc.) ) etc. are often applied. Conventionally, such processing involves reading a visible image obtained by developing photographic film with a microphotometer, converting it into an electrical signal, converting this electronic signal into an A/D converter, and then using a computer. This was done through complicated tasks such as processing.

[Object of the Invention] The present invention makes it possible to record and reproduce an electron beam image or various types of information corresponding to the electron beam image (hereinafter referred to as electron beam image information) with high sensitivity and precision, and furthermore, It is an object of the present invention to provide a method for recording and reproducing electron beam image information that can easily perform various types of processing on the electron beam image information.

[Summary of the Invention] The present invention provides an electron beam image of a sample formed in an electron microscope device or an electron beam diffraction device with a thickness of 10 mm.
An electronic energy latent image is recorded on a stimulable phosphor sheet having a stimulable phosphor layer of ~150 μm, and then at least a part of the electron beam energy stored in the stimulable phosphor sheet is transferred to the stimulable phosphor layer. Electron beam image information consists of emitting fluorescence by irradiating the sheet with electromagnetic waves, detecting this fluorescence, and then performing photoelectric processing on the detected fluorescence to obtain electron beam image information of the sample. It consists of a recording and reproducing method.

Note that the term "electron beam image information" used in the present invention is used to include the electron beam image itself and digital information representing the electron beam image as a symbol such as a combination of numerical values.

[Detailed Description of the Invention] The present invention provides a stimulable phosphor having a stimulable phosphor layer with a specific thickness, which is used as a recording and reproducing medium for an electron beam image of a sample formed in an electron microscope device or an electron beam diffraction device. It is characterized by using a sheet. A stimulable phosphor sheet has a basic structure consisting of a support and at least one phosphor layer provided on one side of the support, and this basic structure is already known. The phosphor layer consists of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state. Generally, a transparent protective film is provided on the surface of the phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is protected from chemical alteration or physical damage. Protects from strong impacts.

A stimulable phosphor sheet having the above structure can be produced, for example, by first adding a particulate stimulable phosphor and a binder to an appropriate solvent such as alcohol, ketone, or ether, and then thoroughly mixing the mixture. It can be formed by preparing a coating solution in which the stimulable phosphor is uniformly dispersed, coating this on a support, and then drying it.

Stimulable phosphors are phosphors that exhibit stimulated luminescence when irradiated with electron beams and then electromagnetic waves (excitation light), but from a practical standpoint, excitation light with a wavelength in the range of 400 to 900 nm is recommended. It is desirable that the phosphor be a phosphor that exhibits stimulated luminescence in a wavelength range of 300 to 500 nm. Examples of stimulable phosphors used in the stimulable phosphor sheet include (1) SrS:Ce, Sm, SrS:Eu, Sm, ThO ₂ :Er, which are described in US Pat. No. 3,859,527;
and La ₂ O ₂ S: Eu, Sm, (2) Described in JP-A-55-12142
ZnS: Cu, Pb, BaO・xAl ₂ O ₃ : Eu (however,
0.8≦x≦10), and M〓O・xSiO ₂ :A (where M〓 is Mg, Ca, Sr, ZN, Cd, or
Ba, A is Ce, Tb, Eu, Tm, Pb, Tl,
Bi or Mn, and x is 0.5≦x≦2.5), (3) (Ba _1-xy , Mgx, Cay) FX: aEu ²⁺ described in JP-A-55-12143 (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 ), (4) Described in Japanese Patent Application Laid-Open No. 12144-1983
LnOX:xA (Ln is at least one of La, Y, Gd, and Lu, X is Cl and
At least one of Br, A is Ce and Tb
and x is 0<
x < 0.1), (5) (Ba _1-x , M ²⁺ x) FX described in JP-A-55-12145: yA (where M ²⁺ is Mg,
At least one of Ca, Sr, Zn, and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr,
At least one of Ho, Nd, Yb, and Er, and x is 0≦x≦0.6, and y is ≦y≦
0.2), (6) Described in Japanese Patent Application Laid-Open No. 160078/1983
M〓FX・xA:yLn [However, M〓 is Ba, Ca,
At least one of Sr, Mg, Zn, and Cd, A is BeO, MgO, CaO, SrO, BaO,
ZnO, _{Al2O3 , Y2O3 , La2O3} , _{In2O3 , SiO2 ,
TiO2} , _ZrO2 , _GeO2 , _SnO2 , _{Nb2O5 , Ta2O5 ,}
and at least one of _ThO2 , Lu is
Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb,
At least one of Er, Sm, and Gd,
X is at least one of Cl, Br, and I, and x and y are each 5×10 ^-5 ≦x
≦0.5 and 0≦y≦0.2], (7) (Ba _1-x , M〓x)F ₂・aBaX described in JP-A-56-116777 ₂ : yEu, zA [However, M〓 is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine,
and at least one of iodine, A is at least one of zirconium and scandium, and a, x, y, and z are respectively 0.5≦a≦1.25, 0≦x≦1, 10 ^-6 ≦y≦2 ×
10 ^-1 and 0<z≦10 ^-2 ], (8) described in JP-A-57-23673 (Ba _1-x , M〓X) F ₂ ·aBaX ₂ :yEu, zB [However, M〓 is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine,
and at least one of iodine,
a, x, y, and z are each 0.5≦a≦
1.25, 0≦x≦1, 10 ^-6 ≦y≦2×10 ^-1 , and 0<z≦2×10 ^-1 ], (9) JP-A-57- (Ba _{1 -x} , M _〓 , X is chlorine, bromine,
and at least one of iodine, A is at least one of arsenic and silicon,
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 ], (10) JP-A-58- Described in Publication No. 206678
Ba _1-x Mx _/2 Lx _/2 FX:yEu ²⁺ [However, M is Li,
Represents at least one alkali metal selected from the group consisting of Na, K, Rb, and Cs; L
Sc, Y, La, Ce, Pr, Nd, Pm, Sm,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al,
represents at least one trivalent metal selected from the group consisting of Ga, In, and Tl; X is Cl,
represents at least one halogen selected from the group consisting of Br, and I; and x is
10 ^-2 ≦x≦0.5, y is 0≦y≦0.1], (11) described in JP-A-59-27980.
BaFX・xA:yEu ²⁺ [However, X is Cl, Br,
and at least one kind of halogen selected from the group consisting of I; A is a calcined product of a tetrafluoroboric acid compound; and x is 10 ^-6
≦x≦0.1, y is 0<y≦0.1], (12) A phosphor described in JP-A-59-47289.
BaFX・xA:yEu ²⁺ [However, X is Cl, Br,
and at least one halogen selected from the group consisting of I; A is selected from the group of hexafluoro compounds consisting of monovalent or divalent metal salts of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; is a fired product of at least one kind of compound;
And x is 10 ^-6 ≦x≦0.1, y is 0<y≦0.1
A phosphor represented by the composition formula (13) described in JP-A No. 59-56479
BaFX・xNaX′: aEu ²⁺ [However, X and
X' is each at least one of Cl, Br, and I, and X and a are each 0
≦x≦2 and 0≦a≦0.2], (14) M〓 described in JP-A No. 59-56480
FX・xNaX′: yEu ²⁺ : zA [However, M〓 is
is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X' are each at least one kind of halogen selected from the group consisting of Cl, Br, and I; A is , V, Cr, Mn, Fe, Co, and
at least one transition metal selected from Ni; and x is 0<x≦2, y is 0<y≦
0.2, and z is 0<z≦10 ^-2 ], (15) M
FX・aM〓X′・bM′〓X″ ₂・cM〓X ₃・xA:
yEu ²⁺ [where M〓 is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; M〓 is selected from the group consisting of Li, Na, K, Rb, and Cs at least one alkali metal; M′〓 is Be and Mg
is at least one divalent metal selected from the group consisting of; M is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; is Cl,
is at least one type of halogen selected from the group consisting of Br, and I; X′, X″, and X are at least one type of halogen selected from the group consisting of F, Cl, Br, and I;
And 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], and (16) M〓 described in the specification of Japanese Patent Application No. 193161/1983
X ₂ ·aM〓X′ ₂ :xEu [where M〓 is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
At least one halogen selected from the group consisting of Cl, Br, and I, and X≠
and a is a numerical value in the range of 0.1≦a≦10.0, and x is a numerical value in the range of 0<x≦0.2. .

Among the above-mentioned stimulable phosphors, divalent europium-activated alkaline earth metal halide phosphors [(3), (5) to (16)] and rare earth element-activated rare earth oxyhalide phosphors (4 ) is particularly preferable because it exhibits high-intensity stimulated luminescence. However, the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, but any phosphor that exhibits stimulated luminescence when irradiated with an electron beam and then irradiated with excitation light. It can be something.

Examples of binders for the phosphor layer include proteins such as gelatin, polysaccharides such as dextran, or natural polymeric substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, and vinylidene chloride. Binders represented by synthetic polymeric substances such as vinyl chloride copolymers, polyalkyl (meth)acrylates, vinyl chloride/vinyl acetate copolymers, polyurethanes, cellulose acetate butyrate, polyvinyl alcohol, linear polyesters, etc. can. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl(meth)
acrylates, mixtures of nitrocellulose and linear polyesters and mixtures of nitrocellulose and polyalkyl (meth)acrylates.
Note that these mixtures may be crosslinked with a crosslinking agent.

The mixing ratio of the binder and the stimulable phosphor varies depending on the characteristics of the desired stimulable phosphor sheet and the type of phosphor, but generally the mixing ratio of the binder and the stimulable phosphor is 1. :1 to 1:100 (weight ratio), and especially 1:8 to 1:40 (weight ratio)
It is preferable to choose from the range.

The support may be selected from various materials used as supports for intensifying screens (or intensifying screens) in conventional electron beam photography, or materials known as supports for stimulable phosphor sheets. You can choose. Examples of such materials include films of plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, ordinary paper,
Examples include baryta paper, resin-coated paper, pigment paper containing pigments such as titanium dioxide, and paper sized with polyvinyl alcohol.

However, when considering the characteristics and handling of the stimulable phosphor sheet as an information recording material, a particularly preferred material for the support in the present invention is plastic film. This plastic film may be kneaded with a light-absorbing substance such as carbon black, or may be kneaded with a light-reflecting substance such as titanium dioxide.

In known stimulable phosphor sheets, the phosphor layer is used to strengthen the bond between the support and the phosphor layer, or to improve the sensitivity or image quality (sharpness, granularity) of the stimulable phosphor sheet. A polymeric substance such as gelatin is applied to the surface of the support to form an adhesion imparting layer, or a light reflective layer made of a light reflective substance such as titanium dioxide, or a light absorbing substance such as carbon black. It is known to provide a light absorption layer or the like. The support for the stimulable phosphor sheet used in the present invention can also be provided with these various layers, and their configurations can be arbitrarily selected depending on the desired purpose, use, etc. of the stimulable phosphor sheet. be able to.

Furthermore, as described in Japanese Unexamined Patent Publication No. 58-200200 by the present applicant, in order to improve the sharpness of the obtained image, the surface of the support on the phosphor layer side (the phosphor layer of the support When the side surface is provided with an adhesion-imparting layer, a light-reflecting layer, a light-absorbing layer, etc., minute irregularities may be formed on the surface (meaning the surface).

The layer thickness of the phosphor layer provided in the stimulable phosphor sheet used in the recording and reproducing method for electron beam image information of the present invention is required to be 10 to 150 μm. In other words, in known radiation image conversion methods using stimulable phosphor sheets, the layer thickness is generally
A phosphor layer of about 200 μm is used. However, according to the research of the present inventor, such a layer thickness
It has been found that when a stimulable phosphor sheet having a phosphor layer of about 200 μm is used as an image recording means for an electron beam image, the line sharpness of the resulting image does not necessarily reach a satisfactory level.

As a result of further research into the reason for this, the present invention found that short-wavelength electron beams used in electron microscopes and electron diffraction are more easily absorbed by the stimulable phosphor than X-rays, and therefore the phosphor layer is not irradiated with the electron beam. Most of the electron beams are absorbed by the phosphor existing near the surface of the phosphor layer, and therefore the phosphor existing below the phosphor layer hardly contributes to improving sensitivity. On the other hand, it was discovered that in the excitation/photostimulation process performed using electromagnetic waves such as laser light, the electromagnetic waves are easily scattered by the lower phosphor. In other words, the phosphor located at a certain depth or more from the surface does not contribute much to increasing sensitivity, but rather has a strong effect of reducing the line sharpness of images obtained using the stimulable phosphor sheet. found.

Based on the above-mentioned development findings, the present invention further develops the thickness of the phosphor layer that balances sensitivity and sharpness at the most practically desirable level when using a stimulable phosphor sheet as an image recording means for electron beam images. As a result of investigation, it has been found that setting the thickness of the phosphor layer within the range of 10 to 150 μm is most suitable for achieving the above-mentioned desired balance. The thickness of the fluorescent layer is more preferably 30 to 120 μm, and particularly preferably 30 to 100 μm.

In addition, when producing a stimulable phosphor sheet, the stimulable phosphor layer does not necessarily need to be formed by directly applying a coating liquid onto the support as described above, and for example, it is not necessary to form the stimulable phosphor layer by directly applying a coating liquid onto the support. After forming a phosphor layer by applying a coating liquid onto a sheet such as a plastic sheet and drying it, the phosphor layer is bonded to the support by pressing it onto the support or using an adhesive. may be joined.

Furthermore, for the purpose of improving image sharpness, the coating liquid contains an average reflectance in the excitation light wavelength range of the photostimulable phosphor, an average reflectance in the stimulated emission wavelength range of the photostimulable phosphor, and a A coloring agent having reflective properties such as less than As such a coloring agent, for example, JP-A-55-
Colorants such as those disclosed in Japanese Patent Application Laid-open No. 163500 and Japanese Patent Application Laid-open No. 57-9630 can be mentioned.
Alternatively, the coating liquid may contain a white powder as described in JP-A-55-146447 for the purpose of improving the sharpness of the image. Note that the shape of the stimulable phosphor sheet may be any one of an endless belt shape, a roll shape, a shape cut into individual sheets, and the like.

A transparent protective film may be provided on the phosphor layer according to known techniques. However, the stimulable phosphor sheet used in the present invention does not necessarily need to be provided with a transparent protective film. That is, stimulable phosphor sheets used in X-ray imaging systems are often processed in the atmosphere and moved by various conveyance systems, and therefore physical or chemical damage to the phosphor layer is likely to occur. Therefore, most conventional stimulable phosphor sheets have been used with a protective film attached. However, for stimulable phosphor sheets used in electron microscopes and electron diffraction imaging systems, at least the electron beam image recording operation is performed in a vacuum system, and the readout of recorded images is also performed in a vacuum system. Furthermore, since the transport system for the stimulable phosphor sheet is often relatively simple, physical or chemical deterioration of the phosphor layer is less likely to occur. On the other hand, if the protective film is made too thick, it becomes difficult for the irradiated electron beam to pass through the protective film, resulting in a decrease in the amount of electron beam that reaches the phosphor layer. Therefore, in the stimulable phosphor sheet used in the present invention, a protective film is not provided, or if it is provided, the film thickness is
It is preferable to use a thin transparent protective film with a thickness of about 5 μm or less.

The transparent protective film may be made of a transparent material such as a cellulose derivative such as cellulose acetate or nitrocellulose; or a synthetic polymer material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copolymer. It can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a polymeric substance in an appropriate solvent. Alternatively, it can also be formed by a method such as adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide, etc. to the surface of the phosphor layer using a suitable adhesive.

That is, the stimulable phosphor sheet used in the present invention can be manufactured by the method described above.

Next, examples of each operation of the method for recording and reproducing electron beam image information of the present invention will be explained in detail using an electron microscope apparatus as an example.

FIG. 1 schematically shows an electron microscope image information recording and reproducing apparatus preferably used in carrying out the storage and reproducing method of the present invention.

This electron microscope image information recording and reproducing device 1 is installed at the lower part of the mirror body 1a of an ordinary electron microscope so that at least when recording electron microscope image information, it belongs to the same vacuum system as the imaging plane of the transmission electron beam image. Arranged stimulable phosphor sheet 10 and stimulable phosphor sheet 1
A reading section 1b is provided, which includes an excitation means for scanning with excitation light while the stimulable phosphor sheet 10 is kept in a vacuum state, and a detection means for photoelectrically detecting stimulated luminescence emitted from the stimulable phosphor sheet 10. This mirror body 1
A and a part of the reading section 1b (inside the hatched frame in the figure) are maintained in a vacuum state by well-known means while the electron microscope is moving.

The mirror body 1a includes an electron gun 3 that emits an electron beam 2 at a uniform speed, at least one focusing lens 4 consisting of a magnetic lens and an electrostatic lens that focus the electron beam 2 onto a sample surface, a sample stage 5, and a focusing lens. It is composed of an objective lens 6 similar to the lens 4, and a projection lens 7. The electron beam 2 transmitted through the sample 8 placed on the sample stage 5 is refracted by the objective lens 6 to form an enlarged scattered image 8a of the sample 8. This enlarged scattering image 8a
is projected onto the image plane 9 by the projection lens 7 (8b in the figure).

The reading unit 1b is configured to excite a plurality of stimulable phosphor sheets 10, a He-Ne laser tube, etc. that are fixedly placed on an endless belt that is passed around a cylindrical drive roller 101 and a cylindrical driven roller 102. An excitation means comprising a light source 11 and an optical deflector 12 such as a galvanometer mirror that deflects the excitation light beam 11a emitted from the excitation light source 11 in the width direction of the sheet 10, and the sheet 10 by irradiation with the excitation light.
A photoelectric converter 15 such as a photomultiplier, which is provided on the emission end face of the condenser 14 that collects stimulated luminescence emitted from the photoelectric converter 15, which converts the stimulated luminescence into an electrical signal by photoelectrically converting the stimulated luminescence into an electrical signal.
It has a detection means consisting of. The endless belt is appropriately rotated in the direction of arrow A by a drive roller 101 rotated by a drive device (not shown).

When the shutter (not shown) provided between the mirror unit 1a and the reading unit 1b is opened, the sample 8 is transmitted through the stimulable phosphor sheet 10 placed at the recording position (i.e., the imaging plane 9). The electron beam is irradiated,
An electron beam energy image (latent image) corresponding to the enlarged scattering image 8b of the sample is recorded and accumulated. Next, this stimulable phosphor sheet 10 is moved to a reading location by rotation of a drive roller. In the apparatus shown in FIG. 1, an excitation light beam 11a is scanned in the width direction of a stimulable phosphor sheet 10 by an excitation light source 11 such as a laser light source disposed outside and an optical deflector 12 such as a galvanometer mirror. Translucent wall member 19a
By moving the sheet 10 in a direction perpendicular to the width direction (in the direction of arrow A) by a drive roller 101, the image accumulated portion on the sheet 10 is scanned. By this excitation light, the stimulable phosphor sheet 10
The stimulated luminescence generated from the light collector 14 is transmitted from the incident end face (end face facing the sheet 10) of the light collector 14.
The photomultiplier tube 15 connected to the exit end face receives the light continuously through the photomultiplier tube 15 connected to the exit end while being guided by total internal reflection. Detected.

The electrical signal read by the photomultiplier tube 15 is transmitted to an image processing circuit 16, subjected to necessary image processing, and then sent to a necessary image reproduction device. This playback device is compatible with display 1 such as CRT.
7, a recording device that performs optical scanning recording on photographic film, or a device that temporarily records on a storage device 18 such as a magnetic tape.

After the reading is completed, the stimulable phosphor sheet 10
is sent to the erasing zone 20 while being placed on the belt. In the erasing zone 20, erasing light emitted from an erasing light source 21 such as a fluorescent lamp provided outside the vacuum system is irradiated onto the sheet 10 through the translucent wall member 19b. This erasing light source 21 irradiates the stimulable phosphor sheet 10 with light included in the excitation wavelength range of the phosphor, thereby erasing the afterimage accumulated in the phosphor layer of the stimulable phosphor sheet 10. It emits noise due to radioactive elements contained in the raw materials of the sensor, and examples of light sources for erasing this include a tangle lamp, a halogen lamp, as shown in Japanese Patent Application Laid-Open No. 11392/1982 An infrared lamp, a laser light source, or the like may be used as desired.

Although the example in which an enlarged scattering image of the sample 8 is recorded and reproduced using a transmitted enlarged 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. Figure 2 shows sample 48.
This figure shows how a diffraction pattern 48c is recorded. In this example, the electron microscope 41 is equipped with an intermediate lens 40 between an objective lens 46 and a projection lens 47.
The diffraction pattern 48c of the sample 48 formed on the back focal plane is transferred to the imaging plane 4 by the intermediate lens 40 and the projection lens 47 that are focused on the back focal plane.
9 is enlarged and projected. In this case as well, the image forming surface 4
If a stimulable phosphor sheet 1050 is placed at 9,
An enlarged image (latent image) of the diffraction pattern 48c by the transmitted enlarged electron beam 42 is recorded on the sheet 1050. This recorded diffraction pattern 48c can be read in exactly the same manner as explained in FIG. 1, and the read image can be displayed on a CRT or
Or you can play it as a hard copy.

Furthermore, in order to eliminate the influence of fluctuations in recording conditions or to obtain electron microscope images with excellent observability, it is necessary to record and accumulate transmission enlarged latent images (enlarged scattered images or enlarged diffraction patterns) on stimulable phosphor sheets. The recording pattern determined by the recording state of the sample, the properties of the sample, the recording method, etc. is determined before outputting a visible image for sample observation, and the reading gain is adjusted appropriately based on the accumulated recorded information. It is preferable to adjust the signal to a suitable value or to perform appropriate signal processing.

Furthermore, in order to obtain a reproduced image with excellent observability, it is required to determine the recording scale factor so that the resolution is optimized according to the contrast of the recorded pattern.

As a method of grasping the accumulated information of the stimulable phosphor sheets 10 and 50 prior to outputting a visible image, for example, a method such as that disclosed in Japanese Patent Application Laid-open No. 89245/1989 can be used. . In other words, the stimulable phosphor sheet is prepared in advance using excitation light of lower energy than the excitation light to be irradiated during the reading operation (main reading) to obtain a visible image for observation of the sample 48, prior to the main reading. A reading operation (pre-reading) is performed to grasp the information recorded on sheets 10 and 50, the accumulated recorded information on sheets 10 and 50 is grasped, and then the main reading is performed,
This can be achieved by appropriately adjusting the reading gain or performing signal processing based on the pre-read information.

Further, as a photoelectric reading means for reading stimulated luminescence emitted from the stimulable phosphor sheets 10 and 50,
In addition to using the photomultiplier tube 15 as described above, solid-state photoelectric change elements such as photoconductors and photodiodes can also be used (Japanese Patent Application No. 58-86226).
(See the specifications of Japanese Patent Application No. 58-86227, Japanese Patent Application No. 58-219313, and Japanese Patent Application No. 58-219314, and Japanese Patent Application Laid-Open No. 1982-121874). In this case, a large number of solid-state photoelectric conversion elements may be configured to cover the entire surface of the sheets 10, 50 and may be integrated with the sheets 10, 50, or may be integrated with the sheets 10, 50.
may be placed in close proximity to. Also,
The photoelectric reading means may be a line sensor in which a plurality of photoelectric conversion elements are connected in a linear manner, or one solid-state photoelectric conversion element corresponding to one pixel may be provided on the entire surface of the stimulable phosphor sheet 10, 50. It may be configured to be scanned across.

In the above case, the reading light source can be a point light source such as a laser, or a light emitting diode (LED).
The light source may be a line light source such as an array formed by arranging semiconductor lasers or the like in a row. By performing reading using such a device, the reading efficiency of stimulated luminescence emitted from the stimulable phosphor sheets 10 and 50 is increased, and at the same time, the solid angle of light reception is increased to improve S/
N can be increased. In addition, the obtained electrical signal is not generated by time-series irradiation of excitation light;
The readout speed can be increased because the time series is processed by the electrical processing of the photodetector.

In the above, the reading operation of the electron beam image such as the transmitted enlarged electron beam image (latent image) recorded on the stimulable phosphor sheet is carried out while the sheet is placed in the vacuum system. Of course, the operation can also be carried out by taking the sheet out of the vacuum system.

Further, when reading and reproducing the electron beam image recorded on the stimulable phosphor sheet, in addition to reproducing the image as a visible image, the image can also be displayed as a symbol such as a numerical value.

[Effects of the Invention] According to the present invention, since an electron beam image is recorded on a stimulable phosphor sheet that has a balance between sensitivity and sharpness, it is possible to reproduce electron beam image information with high precision. Therefore, the amount of electron beam exposure can be reduced and damage to the sample can be reduced.
In addition, since the reproduced image can be immediately displayed with high precision on a CRT, etc., a clear monitor image can be obtained by using this reproduced image as a monitor image for focus adjustment of an electron microscope or electron beam diffraction.
It becomes possible to perform focus adjustment with a low electron exposure amount, which was previously impossible.

Moreover, in the present invention, since the electron beam image information is read as an electrical signal, it is extremely easy to perform image processing such as gradation processing and frequency emphasis processing on the electron beam image information. Image analysis such as processing, three-dimensional image reconstruction, and image binarization can be performed much more easily and quickly than before by inputting the electrical signals to a computer.

Furthermore, the stimulable phosphor sheet that stores and records electron beam image information can be used repeatedly by being subjected to treatments such as light irradiation and heating, so according to the present invention, when a conventional silver halide photographic system is used, This method not only has higher precision but also can reproduce electron beam image information more economically than other methods.

Next, examples of the present invention will be described.

Example 1 Manufacture of stimulable phosphor sheet Methyl ethyl ketone was added to a mixture of phosphor (BaFBr: 0.0005Eu ²⁺ ) particles and linear polyester resin, and nitrocellulose with a nitrification degree of 11.5% was further added to produce a phosphor. A dispersion containing particles in a dispersed state was prepared. Next, after adding tricresyl phosphate, n-butanol, and methyl ethyl ketone to this dispersion, the mixture is sufficiently stirred and mixed using a propeller mixer to ensure that the phosphor is uniformly dispersed and that the mixing ratio between the binder and the phosphor is adjusted. is 1:10, particle size is 25~
A 35PS (25°C) coating solution was prepared.

Next, the coating solution was uniformly applied using a doctor blade onto a titanium dioxide-mixed polyethylene terephthalate sheet (support, thickness: 250 μm) placed horizontally on a glass plate. After coating, the support with the coated film formed thereon was placed in a dryer, and the internal temperature of the dryer was gradually raised from 25°C to 100°C to dry the coated film. In this way, various layer thicknesses (32-160μ) can be applied on the support.
32, 50, 80, 112, 160 μm) phosphor layers were formed.

Then, by placing and adhering a transparent film of polyethylene terephthalate (thickness: 6 μm, coated with a polyester adhesive) on top of this phosphor layer with the adhesive layer side facing down,
A transparent protective film was formed to obtain a stimulable phosphor sheet composed of a support, a phosphor layer, and a transparent protective film.

Recording and reproducing test of electron microscope images (1) Electron microscope Electron microscope (JEM-100CX) manufactured by JEOL Ltd.
Measurements were carried out using the following electron beam irradiation conditions.

Accelerating voltage: 100KV Current density: 1.4×10 ^-10 A/ ^cm2 Irradiation time: 1 second (2) Sensitivity measurement After irradiating the stimulable phosphor sheet with X-rays at a tube voltage of 80KVp, it was excited with He-Ne laser light. do,
The sensitivity (stimulated luminance) of the sheet was measured.
The sensitivity (brightness) measured for each stimulable phosphor sheet was obtained as a relative sensitivity (relative brightness) with the sensitivity measured on a sheet with a 160 μm thick phosphor layer as 100, and these were plotted as a graph. It is shown in Figure 3.

(3) Measurement of image sharpness A plurality of line units to be measured, each consisting of three black lines with the same line width arranged at the same interval in the horizontal direction, are measured, and the line width and line spacing are sequentially changed. A chart for measuring image sharpness (0.50 line pairs/mm to 5.00 line pairs/mm) arranged in parallel was placed on the stimulable phosphor sheet, and electron beam irradiation was performed under the above conditions. Then, the sheet was heated to He
-The phosphor is excited by scanning with a Ne laser beam (wavelength: 632.8 nm), and the stimulated luminescence emitted from the phosphor layer is received by a photodetector (photomultiplier tube with spectral sensitivity S-5) to generate an electrical signal. This was converted into a visible image on a photographic film using an image reproducing device to obtain a chart for measuring image sharpness. The density distribution of this chart image is read with a microphotometer, the output amplitude of the chart image corresponding to 0.50 line pairs/mm is divided by the output amplitude of the chart image corresponding to 5.00 line pairs/mm, and the value is determined as the sharpness value. And so. That is, the larger the sharpness value, the higher the image sharpness.

The sharpness measurement test described above was carried out on each stimulable phosphor sheet with a different thickness of the phosphor layer, and the sharpness values obtained in each test were shown in the third graph.
As shown in the figure.

From the results shown in Figure 3, the layer thickness of the phosphor layer is 10
It can be seen that the stimulable phosphor sheet of ~150 μm has balanced sensitivity and sharpness in recording and reproducing electron beam images, and is useful as a practically excellent recording and reproducing means.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an electron microscope image recording and reproducing apparatus that can be used to implement the electron beam image information recording and reproducing method of the present invention, and FIG. 2 is a schematic diagram showing an example of a similar recording and reproducing apparatus. FIG. 7 is a schematic diagram showing another configuration example. Figure 3 shows the sensitivity and sharpness of each stimulable phosphor sheet measured by implementing a method for recording and reproducing electron beam image information using stimulable phosphor sheets with various layer pressures of the phosphor layer. This is a graph showing an example of the relationship between layer thickness and horizontal axis. 1... Electron beam image information recording and reproducing device (electron microscope), 2... Electron beam, 9... Imaging surface of electron microscope,
DESCRIPTION OF SYMBOLS 10...Stormable phosphor sheet, 11...Excitation light source, 11a...Excitation light beam, 12...Light polarizer, 14...Concentrator.

Claims (1)

[Claims] 1. An electron beam image transmitted through a sample or reflected from a sample is recorded as an electronic energy latent image on a stimulable phosphor sheet having a stimulable phosphor layer with a thickness of 10 to 150 μm. Next, at least a part of the electron beam energy accumulated in the stimulable phosphor sheet is emitted as fluorescence by irradiating the stimulable phosphor sheet with electromagnetic waves, and after detecting this fluorescence, the detected fluorescence is detected. A method for recording and reproducing electron beam image information, which comprises obtaining electron beam image information of a sample by subjecting it to photoelectric treatment. 2. The recording and reproducing method according to claim 1, wherein the stimulable phosphor layer of the stimulable phosphor sheet has a thickness in the range of 30 to 120 μm. 3. The recording and reproducing method according to claim 2, wherein the stimulable phosphor layer of the stimulable phosphor sheet has a thickness in the range of 30 to 100 μm. 4. The recording and reproducing method according to claim 1, wherein a protective film having a thickness of 5 μm or less is provided on the surface of the stimulable phosphor layer of the stimulable phosphor sheet. 5. The recording and reproducing method according to claim 1, wherein the surface of the stimulable phosphor layer of the stimulable phosphor sheet is exposed. 6. The stimulable phosphor layer of the stimulable phosphor sheet is a divalent europium-activated alkaline earth metal halide phosphor or a rare earth element-activated rare earth oxyhalide phosphor dispersed in a binder. A recording and reproducing method according to any one of claims 1 to 5.