JPS61163314A - Scan microscope - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning microscope used to handle radioactive samples, ie, radioactive materials.

According to one aspect of the invention, a scanning microscope includes a source of coherent electromagnetic radiation, an apparatus for supporting an object to be viewed, and a device for receiving a collimated beam of electromagnetic radiation from the source and focusing the radiation onto the object. devices that respond to radiation from an object to form an image of the object, and devices that effect relative movement between a focusing device and a support device to scan the object.

Radiation may be reflected from an object or transmitted through the object.

According to one embodiment of the device of the invention, the support device is moved to produce a frame scan and the converging device is moved to produce a line scan.

The xi radiation may be polarized before being focused, and a device may be provided to rotate the plane of polarization, for example, to obtain different imaging seeds.

There may be a visible display element that moves in response to the relative movement, the intensity of which changes depending on the intensity of the radiation emanating from the object.

In this way, an enlarged image of the object is rendered by each of the display elements in turn as the relative movement occurs.

The sensing device may have a capacitance whose value changes in response to the line scanning.

The response device includes a beam sinter through which the collimated beam passes, a photodiode which receives radiation reflected from the object from the beam sinter, and a visible display connected to the 7-photodiode 9 for displaying an image of the object. Includes equipment.

Although the invention can be implemented in any number of ways, it will be described below by way of example only and with reference to the accompanying drawings, in which it has the potential to be implemented in any number of ways.

In FIG. 1, Ll is a low-power radar, and a beam 10 emitted from it passes through a beam exnoder 01 and is converted into a wide beam to become a monochromatic beam 11.

Beam 11. is converged by lens L2 disposed at the end of scanning arm 05 to form a small spot (for example 74
m). This spot is formed on the surface of the sample S. As the lens L2 moves back and forth across the sample surface, another area of the beam 11 is focused by the lens L2 to produce a small spot (eg 74 m). The position shown by the solid line and the position shown by the broken line of the above-mentioned scanning lens) eL2 indicate the limits of the scanning range of this lens. The light beam reflected by the sample travels the same optical path as the incident optical path in the opposite direction, passes through lens L2, and then passes through beam splitter 0.
The beam 11a passes through the converging lens 04 and enters the photodiode d+, and the output signal of the photodiode passes through the amplifier 69 and reaches the display device 10.The photodiode d1 An analog output signal is generated, and the output signals of and are input to a visual display device.

The display device has a visible display element that moves in response to relative movement between the scanning lens and the sample support, the intensity of which changes depending on the output signal of the photodiode.

One form of scanning device is shown in FIG. The scanning lens L2 is mounted on one end of an arm 05 fixed to a threaded rod 51 fixed to the structure 52. The other end of arm 05 is 21! 1 between the electromagnets 53 and 54, which can be selectively energized by a storm force multiplier 55, for example, between the two vibration limits of the entire arm 51. 2
Photographing is performed at a self-oscillation frequency of 00 cycles per second. Therefore,
The scanning lens L2 will trace an arc in a plane parallel to the sample surface (for clarity, the sample is shown away from its support device 61).

The sample stage, ie, the sample support device 61, is reciprocated in the Y direction (with a period of 7 seconds, for example) by a motor 62, and the transducer 63 generates a signal in response to this movement in the Y direction. Both the movement of the scanning lens L2 in the X direction and the movement of the sample in the Y direction are perpendicular to the optical axis 64.

In the case of line scanning, the sample is not moving at high frequencies, so there is no need for the expensive, high power two-in scanning drives that would otherwise be required.

The position of arm 05 is determined by position sensors 56 and 57 in the X direction.
Also, the Y direction is measured by a transducer 63, but such a sensor can have an analog output or a digital output as required. For example, the transducer is a grating dage (gra
ting gauge). Also, the position sensors 56 and 57 are connected to each other as two plates forming a capacitor together with the central plate 58.
The capacitance change between 6 and 58 and the capacitance change between 57 and 58 are sensed and an output signal representing the movement in the X direction is generated via a connected charge amplifier. It is also possible to provide an image forming apparatus so as to correct the deviation from orthogonality between the X direction and the Y direction. The output signal is supplied to the display device TO to move the spot in the X direction and in the Y direction in response to the relative movement of the support device and the scan lens. The intensity of this spot is modified according to the reflected light from the sample St, and this modified intensity is detected by the photodiode dl. The display on the screen of the display device 70 may be photographed, for example, to leave it as a permanent image. Since the duration of exposure is set to match the time required to scan the /frame in the Y direction, an image is generated and saved as a negative image. The signal can be applied to a video storage tube and the stored display can be viewed on the storage tube. It is expected that a spot as small as 0g5m can be obtained using helium-neon Radhe if a suitable one is selected for the Rede light converging lens L2. In order to obtain even higher resolutions, it is also possible to use nickel-cadmium lede or X-ray sources that emit light in the ultraviolet-visible range.

[harmonics scan microscope
ningmicroscope)J can also be used.

This is scanned using a scanning optical microscope '1II1. By applying f- it is possible to achieve resolutions beyond the typical limits limited by the illumination light. Its operation is based on the fact that the crystals it is made of lack a center of symmetry and therefore generate high-intensity harmonic components of light. The light reflected from the sample at the fundamental frequency is p-filtered and extinguished by the filter circuit, and an image of the sample is produced in the usual manner by only the harmonic components of the light.

The purpose of providing the lens L2 is simply to converge a parallel beam of light. For this reason, there is no need to perform sophisticated aberration correction on the lens. The lens L2 can be replaced by a diffraction grating, and the scanning arm can be replaced by a two-layered piezoelectric element whose dimensions are reduced.

The composite device thus constructed is capable of capturing images at a much higher frequency than before, and therefore images are formed at a higher frame frequency than in the arrangement shown in FIG.

It is also possible to provide a device that applies a bending moment to one end of the scanning arm 05 to change the position of the lens L2 along a direction parallel to the optical axis 64 so that the lens L2 performs a focusing action, for example, This is done using a pole piece T2 of a round, 'RL magnet, arranged above or below the scanning element T3.

Using the same mechanism as the companion device just described, it is possible to maintain the convergence position of lens L2 during the seven scans.

This will be explained with reference to FIGS. 1 and 3. Scanner arm 0
It was placed at one end of 5. 4i amount of soft iron - one piece γ2
An electromagnet T1 is mounted on the support device 61 in close proximity to. When a current is passed through the coil of electromagnet T1, the scanning element T
3 is pulled upward along two directions. Automatic beam focusing occurs in the quadrant direction (perpendicular to the incident beam)
A photodiode detector placed in d! (Figure S)
This is done as described below. The beam that has already been split by the beam splitter 03, enters the sample, is reflected by the sample and returns, is split again by the beam splitter 06, and the beam splitter 06 and the photodiode d
! The light passes through a cylindrical lens OT with a small curvature inserted between the two and enters the photodiode d. Due to the total astigmatism introduced in this process, the returned beam will have an asymmetrical outer shape, but this asymmetrical outer shape should be passed through the excitation coil of the electromagnet (position of the scanning element 73).
Used to determine the direction of the control signal.

Scanning microscopes are essentially remotely operated and are particularly suitable for examining radioactive samples in shielded rooms. Second
A bundle of control cables 22 is the only connection between the illustrated control tube and flannel 2o and the components located within the shielded chamber 21. The optical path extension tube used to take the conventional microscope image out of the shielded chamber is no longer needed. 1 The output of the microscope is in the form of electrical signals, which can be easily connected to a computer via an interface for automatic measurement, image analysis, image processing, etc. Compared to conventional devices, the present device is much smaller, much more interconnected and therefore not dependent on shielded chambers. Unlike conventional J-microscopes that are used in a shielded room, the microscope of the present invention allows connection cables to be disconnected, moved within the shielded room, replaced, or removed as needed. It is possible to do so.

FIG. 2 depicts the inside of the shielded chamber of the microscope of the present invention. The operator only needs to be present in front of the shielded chamber for a short period of time while the sample is placed in the microscope. The figure shows an optical components storage cabinet 83 having a low-intensity radioactivity area 8o, a medium-intensity radioactivity area 81, a high-intensity radioactivity area 82, and a low-intensity radiation source L1.

Scanning optical head microscopes use a Rade light source. The output level of the Rede light source can be selected from a wide range, but it should be large enough to brighten the conventional microscope illumination rung (
(Do not use a high-power radar to illuminate the conventional g-microscope in consideration of damage to the II). Since all the light is converged downward to form a soot with a diameter of about /1 m, even the signal reflected by the reflector with poor performance is sufficient compared to the case of microscopes other than the type of the present invention. It has size.

For this reason, the following advantages of the Lede scanning smear mirror can be obtained.

(Hiro) The amplifier connected to the detector only needs to have a small gain, so the S/N ratio of the image is high.

(b) Exposure of a microscope objective lens to radiation usually causes it to darken, eventually reaching a point where the intensity of the image decreases to the point that the objective lens needs to be replaced.

In the case of the scanning microscope of the present invention, this is not a problem.

That is 1. This is because sufficient light can be obtained to automatically adjust the microscope so that a constant intensity is maintained throughout the useful life of the f4 microscope.

The above-mentioned properties of scanning microscopes are particularly important when the sample is observed in crossed Nicols (dark field) using polarized light.

In this state, it is not uncommon for the image intensity to be several orders of magnitude smaller than the normal intensity, and it is very common for the performance of a normal microscope to be severely limited. It is.

Unlike conventional microscopes, the microscope 30 of the present invention does not require adjustment by changing lenses when working with radioactive materials. The various parts of the microscope 3o arranged in the shielded chamber 21 are low-priced and small;
This feature also applies to non-nuclear uses. Therefore, in the example shown in FIG. 2, the spare microscope *31 is kept on standby at all times in the shielded room. This means that the microscope is available for use at all times.

When using conventional microscopes, the operator can only adjust the image seen at the eyepiece under limited conditions. To change the magnification, the operator must replace either the M-eye lens or the objective lens. For a microscope located behind a shielding wall, it is a time-consuming operation if the magnification must be increased and decreased frequently. In contrast, in the case of a scanning optical microscope, the magnification is not a function of the focal length of the lens, but can be quickly and easily adjusted by varying the sensitivity of the position measuring transducer on the control panel 2a.

This allows the video signal to be displayed in a large or small area on the screen.

The arrangement shown in FIG. 6 is particularly suitable for operations using polarized light. The radar L1 (FIG. 1) which emits polarized light is oriented in such a way that the polarized beam 'sgeritter 03 coincides with the plane through which the maximum amount of light is transmitted. The variable phase delay element (Nokubinet-Soleil compensator) 02 rotates the polarization plane of the incident beam by an angle θ and transmits the beam. Since the beam passes through the delay element 02 once again after being reflected by the sample, the plane of polarization is also rotated by the angular change θ. When −〇=90°,
All reflected light from the sample is reflected by the beam splitter 03 and enters the photodiode d. =θ=/
For gOP, only the light that has been rotated 906 by the structure of the sample is collected by the diode (a large part of the light is reflected by the sample and returned to the radar after passing through the beam splitter and is attenuated). For samples whose plane of polarization can be rotated to reveal surface structure, the conditions described above can be used to image such samples.

Therefore, while rotating the phase delay element 02, the detector dL receives a beam of light whose light control surface is rotated by the sample, thereby making it possible to analyze the structure of the sample.

For example, in the case of a transparent biological sample, the interior of such sample can be detected by placing a photodiode in a position that receives the transmitted radiation and detecting the radiation after it has passed through the sample rather than detecting the reflected light. It becomes possible to obtain knowledge of +G construction.

The MII diagram shows the details of a device that inputs images and reports obtained by the Kengo e-mirror into a computer and processes them. In order to convert the scanning method from a sinusoidal scanning input to a rask-forming scanning input, an image signal 9 giving scanning information regarding the vertical orientation in the X-axis direction is used.
1 is stored in the line scan information buffer [9G.

Similarly to the above, the sawtooth image code 92 giving scanning information regarding the position in the Y-axis direction is not inputted as is, but is feedback-controlled to take a test forming sawtooth signal waveform. The information stored in the storage device is continuously retrieved and fed through a high speed digital to analog converter 93 to a 7000 scan line artist monitor 94. At the same time, all the operations of inputting information to the outside/outputting information to the outside allow the artist to observe such information on the image monitor while it is being formed in the storage device. This is useful for checking beam convergence and allows the sample to be moved during the scan. The slow-scan original image is captured by a photographic recording electronic circuit 95 that synchronizes the frame scan with the line scan of a ('700 Hz) oscillator.
is displayed on the screen of the display device 70 using .

This allows the same image monitor to be used as a photo recording module by taking a photo of its screen. The keypad 96 controls the computer image processing device via the computer 99.

The image information is stored on the magnetic disk memory 9T that goes to the frame information recording device 98 and returns from the recording device 98, and copies are made from the image monitor/photo recording device 94 as needed. can get.

Many lens aberration scanning optics operate along the traditional principle of using a lens and then obtaining an image of an object by scanning the lens as a two-dimensional image. The device described above differs from this prior art device in that intermediate steps are eliminated and no image is formed until the data is entered into the digital storage device. This is achieved by using parallel beams and by scanning in a direction perpendicular to the optical axis. In that case, the objective lens L2 converges the parallel beam to form a spot whose size is limited by diffraction effects, and also collects the reflected light. Therefore,
This lens exhibits no astigmatism or coma, which would naturally exist if the lens formed a two-dimensional object painter. In addition, since a single line spectrum emitted by Rede is used, there are no errors caused by chromatic aberration. As a result, the only aberration that matters is spherical aberration, which can be significantly corrected. For the same reason, lenses can be calculated and designed to provide maximum flame focal length while at the same time retaining performance limited by diffraction effects. Actually, the lens used has a gap of 3H between the sample St and the lens top 2, whereas the gap obtained with a normal high-performance objective lens is 1 m. As a result, scanning microscopes have protruding parts that make it difficult to secure sufficient clearance using a normal microscope.
It is suitable to use it to obtain an image of a fractured surface having such a protruding portion.

I have already mentioned photographic records. Any method of measuring from photographic film is bound to have errors, but these are the main causes of errors due to the characteristics of the tube, camera, and film, and for example, such errors can reach several Sometimes. The advantages of a scanning mirror device may be fully realized if measurements and operations are based on image data stored in a digital storage device, such as a computer storage device.

Such computer equipment can be designed to achieve an accuracy of 0.7%. The limit of image accuracy is determined by the following λ parameters.

a. Spatial Linearity and Spatial Resolution A. Grayscale Linearity and Resolution In the arrangement of the present invention, many of the aberrations of the optical image are avoided by not forming an optical image and by using a parallel beam. Linearity errors associated with -dimensional and two-dimensional detectors, such as video cameras or television cameras, are avoided by using a single point detector. Spatial linearity will thus depend largely on the characteristics of the position measuring device. A large number of position measuring devices are applicable to microscopes. When using the position measuring device 4, the following requirements must be taken into account.

a Maximum intensity b Maximum resolution C High-speed scanning (for X-direction scanning, J O (7kHz)
d. Non-contact or @placement so as not to adversely affect the performance of the scanner.

The position measuring device can be of analog or digital type, depending on the requirements regarding the interface. Furthermore, another position measuring device may be able to infer information about the position in the X-axis direction from the scanning element, assuming that such scanning information is sinusoidal. Further, it is assumed that the scanning information regarding the position in the Y-axis direction is a sawtooth wave. In this way, it is possible to obtain a high signal-to-noise ratio, perhaps with a compromise of good linearity. Devices of the type described below are believed to meet the above requirements for position measurement.

Optical equipment - Interferometer - Diffraction grating - Polarizing mirror device Magnetic equipment - I/Ductance detector - Eddy current detector - Hall effect detector Electronic equipment - Accelerometer - Strain R - Capacitive detector .

While the discussion regarding spatial linearity was discussed above, spatial resolution is ultimately limited by the size of the scan swath. For the device of the invention, the spatial resolution is 7 μm. The scanning range, and therefore the minimum achievable magnification, is limited by the dynamic range of the position measuring device. However, if a lower resolution can be tolerated, it is possible to achieve a larger scanning WRIli that reaches the scanning limit of the scanner.

The characteristics of gray scale are photodetector / eitai intensifier / 7'
Determined by the noise characteristics of the Ijiitide.

Akichika's photodetector has good performance, with an S/N ratio of 1 pOdB or more and a dynamic range of over three orders of magnitude. The arrangement described above is such that visible light is reflected from the sample and incident on the photodiode, so that the photodiode can be operated in room light conditions, and the photodiode may be a point detector. Therefore, much of the strong light emitted from points other than where the Lede beam is focused is eliminated. Since the device is used under slow scan conditions, the band width of the video intensifier is only J 00 kHz, so the band width is small compared to the noise generated by a television camera, which has a bandwidth of, for example, 10 mHz. It has small noise characteristics in proportion to.

Since the scanning microscope of the present invention produces as output a signal in the form of an electronic signal, such a signal can not only be displayed on a cathode ray tube for viewing by a large number of observers;
The signals described above can be input to the computer via an interface to perform various functions as described below.

l Stored in a memory repository in the form of digital memory.

Yu　Create a hard copy in less time than it takes to take a photo.

, 3. Electronic circuit processing such as improving image quality.

Automatic operations such as weak particle counting.

(a) In the case of the scanning type GO mirror of the present invention, there is a need for remote inspection of images in order to reduce the radiation dose to operators when handling radioactive samples, and there is a need for remote inspection of images, which can be concentrated in a single control room. It is possible to perform operations.

(b) Connecting the microscope of the present invention to other hardware via an interface to perform the following functions.

(1) Improving the quality of images using computers; storing computer memory in large memory storage; ■ Producing hard copies using video output printers instead of taking photographs; Perform parameter measurements, automatic particle counting, etc.

The resolution obtained with the microscope of the present invention is about λμm,
This value is very close to the limit of resolution limited by the wavelength of illumination light. This value is comparable to, if not greater than, the values obtained with conventional devices.

The images obtained with the standing steel microbond of the present invention show the metallurgical characteristics of the sample in detail in a way different from that of conventional microscopy. This microscope is useful for obtaining images of objects that have heretofore been difficult to see using conventional equipment (such as oxide layers).

The device of the invention does not suffer from image quality degradation caused by the effects of radiation on the surface of the lens. Due to the high strength obtained by Rede, any darkening that occurs in the lens can be compensated for.

Due to the high intensity obtained by the LED, it is possible to obtain a more accurate image compared to conventional equipment, with less electrical noise in the displayed image. This is especially true when the intensity of the image is low, such as in

When a microscope is used in a difficult environment such as a shielded room, an advantage arises in that maintenance costs are low. The cost of the "indoor use" parts of the microscope of the present invention does not exceed the total cost of this 4i microscope by 70 gold.

Possible modifications of the scanning quasi-microscope of the present invention include a three-color display system and an extension of the scanning range to a larger area.

By increasing the scanning frequency to obtain images in a shorter amount of time, the operator can move around the sample more quickly. Examples of other possible image display modes will be given below. If a microphone detector is used, the microscope of the present invention has the potential to detect all surface microstructures, unlike the Sound 4II microscope. If infrared reflected light is detected,
It becomes possible to display the electrical conductivity and specific heat of the sample using images. If a spectrometer is inserted into the parallel beam 11 (FIG. 1) and Raman scattered light is detected, knowledge of the ridges of molecules contained in the sample can be obtained. If1 degree of the image changes depending on the position measuring device. Among the many possibilities, perhaps the most accurate are interferometer-type devices, which can achieve resolutions in excess of 1 μm.

The apparatus of the present invention is suitable for high #1 automatic measurement such as particle counting using a computer.

The microscope described in detail above includes a Rede radiation source, a support for the object to be inspected, a device for converging radiation emitted from the radiation source onto the object, a device for relative movement between the support and the convergence device,
The present invention includes an orthogonally movable display and an apparatus for orthogonally moving the display in response to said relative movement.

The microscope as described above also comprises an electromagnetic radiation source, a support for the object to be inspected, a device for focusing the radiation emitted by the radiation source onto the object, a device for effecting a relative movement between the radiation and the support, and Includes a visible display device with a display responsive to radiation from an object.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a scanning optical head microscope of the present invention, Fig. 2 is a schematic diagram of a device for taking a radioactive sample, Fig. 3 is a partially enlarged view of Fig. 2, and Fig. q is a stroke number forming device. , FIG. S shows one embodiment of the image forming apparatus, and FIG. 6 shows another embodiment. 02 Device for rotating the plane of polarization 03 Beam splitter 11 Parallel beams 56, 57, 58 Variable capacitance detector 61 Device for supporting the object 70 Display device Ll Electromagnetic radiation source Ll Converging device S Direct object dl Photodiode Showa Year Month Day 21 Name of invention Scan Ri! Ni Kagami 3,? Relationship with the case of a person who makes a FI correction Applicant 4, agent

Claims (1)

[Claims] 1. A coherent electromagnetic radiation source, an apparatus for supporting an object to be inspected, an apparatus for receiving radiation from the radiation source and directing the radiation onto the object, for forming an image of the object. In a scanning microscope, consisting of a device responsive to radiation from an object, and a device providing relative movement between the radiation and a support device to scan the object, the device receiving the radiation receives a collimated beam of radiation and directs this beam to the object. A scanning microscope characterized by an upward convergence. 2. A microscope according to claim 1, in which the radiation is reflected from an object. 3. A microscope according to claim 1, in which the radiation is transmitted through an object. 4. Claim 1, or Claim 2, in which the radiation is polarized and comprises a device for rotating the plane of polarization.
The microscope described in section. 5. A microscope according to any one of the preceding claims, which includes a display element that moves in response to relative movement. 6. A microscope according to claim 5, including a device for correlating the intensity of the display with the radiation from the object. 7. A microscope according to any of the preceding claims, wherein the converging device moves to produce line scanning, and the support device moves to produce frame scanning. 8. The responsive device includes a beam splitter through which the collimated beam passes, a photodiode that receives radiation reflected from the object from the beam splitter, and a visual display device connected to the photodiode for displaying an image of the object. A microscope according to claim 2. 9. The apparatus of claim 7 including a sensing device having a capacitance that changes in response to the line scan.