JP2008233109A - Near-field optical probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near-field optical probe capable of properly executing spectral analysis in a desired wavelength range in order to carry out recognition of a surface shape of a sample, and analysis of its constituents and the like. <P>SOLUTION: This near-field optical probe 22 is provided with a tapered core 44 formed by sharpening a tip of an optical fiber formed of a material excelling in infrared permeability, and a mask 46 formed on a surface of the tapered core 44 by excluding the tip of the tapered core 44, and characterized by being capable of irradiating a measurement sample with incident light in an infrared range from the tip 48 of the tapered core 44 exposed to the outside from the mask 46 or capturing scattered near-field light from the measurement sample. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a near-field optical probe, and more particularly to improvements in its material and structure.

A general microscope can observe a very small portion of a sample in a non-contact and non-destructive manner. Furthermore, by connecting a spectroscopic analyzer or the like, it is possible to analyze not only the shape and structure of the observation object but also its components and the like, and applications are being made in various fields.
However, a general optical microscope cannot observe anything smaller than the wavelength of light, and its resolution is limited.

On the other hand, although the resolution can be greatly improved in an electron microscope or the like, it is extremely difficult to operate in the atmosphere or in a solution, and a high resolution microscope such as an electron microscope is not necessarily used in the field of handling biological samples. It was not satisfactory.
On the other hand, in recent years, a near-field optical microscope based on a principle different from a general optical microscope or an electron microscope has been developed and its application is expected.
This near-field optical microscope detects so-called near-field light.
For example, when a minute measurement sample is placed on a flat substrate and light is incident at an angle that causes total reflection from the back surface of the substrate, all the propagating light is reflected, but the surface of the substrate and the measurement sample In the vicinity, a surface wave called near-field light is generated.

This surface wave is localized in a region within a distance within the wavelength of light around the object surface.
Therefore, the distance between the probe tip and the surface of the measurement sample can be defined by inserting a sharp probe into the near-field light field to scatter the near-field light and measuring the intensity of the scattered light.
Therefore, by scanning the probe while keeping the intensity of the scattered light constant, the tip position of the probe accurately reflects the unevenness of the surface of the measurement sample.
In addition, the probe tip is only present in the near-field light field, and is not in contact with the measurement sample itself. Therefore, the probe tip is not in contact with the sample, is not destructive, and is smaller than the light wavelength value. Observe.

By the way, in such a near-field optical microscope, in addition to a collection mode (c mode) in which near-field light generated on the sample is scattered and collected by the probe, near-field light generated from the probe is used. There is also a method called illumination mode (i-mode) that illuminates a sample and collects and detects scattered light (or emitted light) of the sample.
The c-mode requires a scattering probe that functions as a scatterer of near-field light, and the i-mode requires a generating probe that selectively generates near-field light.
In other words, when performing near-field measurement, it is necessary to select a microscope mode suitable for the application, set the target resolution, and optimize the probe so that sufficient detection light intensity can be obtained for the target resolution. There is.

Here, a fiber probe having a tapered taper tip and an opening formed by a mask such as a light-shielding metal film is usually formed by a selective chemical etching method or a method of extending the tip of the optical fiber by heating, etc. The tip opening is created by sharpening and depositing a mask such as a metal film on the sharpened fiber, and then selectively removing the light-shielding metal film at the tip.
And only pure quartz is generally used as the material of the probe.

By the way, if the probe is made of pure quartz, the probe only scatters near-field light if only the shape of the measurement sample is grasped. Can be used.
However, in order to perform spectroscopic analysis of the components of the measurement sample at the probe position in the infrared, ultraviolet, etc. in addition to the above visible, it is necessary to spectrally disperse the scattered near-field light from the measurement sample. was there.

That is, in order to perform infrared spectroscopic analysis for analyzing the components of the measurement sample at the probe position, it is necessary to split the scattered near-field light from the measurement sample.
For this reason, it is necessary to have a spectrum width that can be taken. If the visible quartz probe is used, there is no problem in the transmission efficiency in the visible region, but there is still room for improvement in the transmission efficiency in the infrared region. It was.
Moreover, since the conventional probe for atomic force microscope is produced by the silicon semiconductor lamination technique, there is a problem that expensive equipment and complicated processes are required.

Here, if only the surface shape of the measurement sample is to be grasped, the probe only needs to obtain an atomic force between the sample and the sample, and any material can be used as well as the silicon. Can do.
However, if the probe is made of silicon in order to analyze the components of the measurement sample and the like, there is room for improvement because spectral analysis in the visible light, ultraviolet, and infrared regions that do not pass through the silicon cannot be performed. Although left behind, there was no appropriate technology that could solve this.

Furthermore, in order to analyze the components of the measurement sample at the probe position, when performing various emission spectroscopy measurements such as Raman spectroscopy, fluorescence spectroscopy, and photoluminescence spectroscopy, the fiber itself is subjected to Raman scattering by the Rayleigh scattered light from the measurement sample. Since light is generated, the Raman scattered light from the measurement sample to be detected is buried in the Raman scattered light of the fiber itself.
In particular, the Raman scattered light from the measurement sample to be detected is weak light among the scattered light, so the above problem is more serious, and countermeasures against the Rayleigh scattered light have been urgently needed. There was still no suitable technique for the probe that could be solved.

  The present invention has been made in view of the prior art, and its purpose is to grasp the surface shape of a sample and to analyze its components and the like so that it can appropriately perform spectroscopic analysis in a desired wavelength range. It is to provide a probe for field optics.

In order to achieve the object, an infrared near-field optical probe according to the present invention includes a tapered core and a mask.
Here, the tapered core is obtained by sharpening the tip of an optical fiber made of a material having good infrared transmission.
The mask is formed on the surface of the tapered core except for the tip of the tapered core.

Then, the measurement sample is irradiated with incident light in the infrared region or the scattered near-field light from the measurement sample is captured from the tip of the tapered core exposed to the outside from the mask.
In the present invention, it is preferable that the optical fiber made of a material having good infrared transmittance is formed of one or more materials selected from the group consisting of quartz, chalcogenite, fluoride, and silver halide. It is.

In this case, the formation of one or more materials selected from the group consisting of quartz, chalcogenite, fluoride, and silver halide means that when quartz is selected, the quartz is not used alone but chalcogenite, fluoride. A combination with one or more materials selected from the group consisting of a chemical compound and a silver halide.
In the present invention, the scattered near-field light from the measurement sample captured from the tip of the infrared near-field optical probe is analyzed from the infrared spectrum or Raman spectrum of the scattered near-field light. Therefore, it is also preferable that the light is split by one spectroscopic device selected from the group consisting of a diffraction grating type spectroscope, a Fourier transform infrared spectroscope, a variable wavelength infrared laser spectroscope, and a free electron laser spectroscope.

In order to achieve the above object, an atomic force microscope probe according to the present invention includes a base material and a tapered core.
Here, the base material is for scanning the surface of the sample while maintaining a constant distance from the surface of the measurement sample.
Further, the tapered core is made of a material having a good transmission efficiency in a desired wavelength region, and a material in which a dissolution rate ratio with respect to the base material is considered so as to be sharpened with respect to the base material by a chemical etching method. The etching resistance material is sharpened.

Then, from the tip of the tapered core, incident light in a desired wavelength region is irradiated onto the measurement sample, or scattered near-field light from the measurement sample is captured.
In the present invention, as the substrate, it is preferable to use one or more plate-like materials selected from the group consisting of a quartz plate, a fluoride plate, a chalcogenite plate, and a silicon plate.
Further, in the present invention, the etching resistance material is selected from the group consisting of germanium oxide, lanthanoid, actinoid, alumina, aluminum, gold, silver, and silicon oxide having good visible, ultraviolet, and infrared transmission efficiency. Or it is also suitable to form with two or more materials.

In order to achieve the above object, a Raman near-field optical probe according to the present invention includes a tapered core and a mask.
Here, the tapered core is made of a grating fiber capable of selectively removing Rayleigh scattered light from scattered near-field light from the surface of the measurement sample.
The mask is formed on the surface of the tapered core except for the tip of the tapered core.
Then, the measurement sample is irradiated with incident light in a desired wavelength range or the scattered near-field light from the measurement sample is captured from the tip of the tapered core exposed to the outside from the mask.
In the present invention, the taper core surface has a mask excluding the tip by a metallic film made of one or more materials selected from the group consisting of aluminum, gold, silver, germanium, and chromium, Or it is also suitable that the mask which covers the whole core is formed.

  As described above, according to the infrared near-field optical probe of the present invention, one or two or more materials selected from the group consisting of chalcogenite, fluoride, silver halide and the like having good infrared transmittance are used. By using near-field light localized in the vicinity of a minute aperture whose size is equal to or smaller than the wavelength for irradiation or condensing, or by irradiating or collecting near-field light irradiated or condensed By narrowing down, the near-field optical microscope using the probe according to the present invention can perform infrared spectroscopic analysis with a spatial resolution of less than or equal to the wavelength, which has been extremely difficult in the past.

Further, according to the atomic force microscope probe of the present invention, the etching resistance material made of a material having a good transmission efficiency in a desired wavelength region is doped or applied to the base material, and the etching resistance material is sharpened. Since the tapered core is provided, spectroscopic analysis in a desired wavelength region of visible, ultraviolet, and infrared can be favorably performed by an atomic force microscope using the probe according to the present invention.
In addition, by cutting out the base material from the block doped with the etching resistance material, a base material including the etching resistance material can be easily prepared, and sharpening of the etching resistance material can be performed by one chemical etching. Since the method is sufficient, the probe according to the present invention can be mass-produced.

Further, according to the Raman near-field optical probe according to the present invention, the tip of the grating fiber whose bandwidth is designed so that the Rayleigh scattered light can be selectively removed from the scattered light from the sample surface. Since the probe is used, the Rayleigh scattered light is removed by the grating of the grating fiber acting as a rejection filter.
Accordingly, the Raman light generated by the optical fiber itself due to the Rayleigh scattered light can be removed or significantly reduced, so that the Raman light from the measurement sample can be substantially reduced by the near-field optical microscope using the probe according to the present invention. Only for the spectroscopic analysis.

Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of a near-field optical microscope 10 using a probe according to an embodiment of the present invention.
In the figure, a measurement sample 12 is disposed on an inverted triangular total reflection prism 14, and laser light 16 in the infrared region is incident on the total reflection prism 14, and the boundary surface between the sample 12 and the prism 14. Is totally reflected.

In this state, near-field light 18 is generated on the surface side (upper side in the drawing) of the sample 12.
When the tip of the probe 22 made of a pointed optical fiber made of a material having good infrared transmission efficiency is inserted into the field of the near-field light 18, the near-field light 18 is scattered by the tip of the probe 22. .
A part of the scattered light 20 as the scattered near-field light enters the fiber probe 22 and is guided to a detection mechanism described later.

When the surface of the sample 12 is scanned while moving the tip of the probe 22 according to the present embodiment up and down so that the intensity of the scattered light 20 is constant, the sample 12 is not in contact with the unevenness of the sample 12. Can be accurately grasped.
That is, the near-field optical microscope 10 shown in the figure includes the probe 22 as scattered light collection means, the separation information acquisition means 26 that controls the tip of the probe 22 in the vertical direction (Z-axis direction), Spectral information acquisition means 28 for obtaining the spectral information by dispersing scattered light obtained via the fiber probe 22, X and Y axis scanning means 30, and display means 32 are included.

  The probe 22 according to the present embodiment is made of, for example, an optical fiber made of a material having good infrared transparency. Scanned. Further, the separation information acquisition unit 26 includes a detector 34 for obtaining separation information between the sample 12 and the tip of the probe 22 and a Z-axis scanning unit 36, and the scattered light 20 obtained through the fiber probe 22. The Z-axis scanner 36 controls the position of the probe 22 according to the present embodiment in the Z-axis direction so that the intensity of the scattered light 20 is constant based on the output.

The spectrum information acquisition means 28 includes a spectroscope 38, a detector 40, and a spectrum storage 42 for storing spectrum information based on the output of the detector 40.
Here, in the near-field optical microscope 10 according to the present embodiment, the spectroscope 38 is suitable for performing infrared spectroscopic analysis of the near-field light, for example, a diffraction grating type spectroscope, Fourier transform infrared spectroscopy. A spectroscopic device selected from the group consisting of a FTIR, a variable wavelength infrared laser spectrometer, a free electron laser spectrometer, and the like is used.

The near-field light is detected by the detector 40 and stored in the spectrum storage 42 together with the wavelength information obtained from the spectrometer 38.
The display means 32 has the X and Y coordinates of each measurement point from the X and Y axis scanning means 30, the height information of the sample surface at each measurement point from the Z axis scanning means 36, and the spectrum information acquisition means 28. Spectral information or component information at each measurement point is obtained and displayed.
As described above, according to the near-field optical microscope 10 according to the present embodiment, the height information on the surface of the sample 12 and the components at each measurement point on the sample surface from the scattered light 20 collected by one probe 22. Information can be obtained at the same time.

  In addition, the conventional micro-infrared spectroscopic device has only a spatial resolution about the wavelength of light due to the diffraction limit of light, and a sample having a wavelength less than the wavelength, for example, 10 μm or less, could not be measured. On the other hand, the near-field optical microscope 10 according to the present embodiment can appropriately perform infrared spectroscopic analysis of the sample 12 with a spatial resolution equal to or less than the wavelength.

By the way, the light collection efficiency of the scattered light 20 greatly affects the measurement accuracy.
For this reason, the fiber probe 22 that transmits the scattered light 20 from the sample 12 to the spectroscope 38 is required to have high infrared transmission efficiency, that is, transmission efficiency.
Therefore, in the near-field optical microscope 10 according to the present embodiment, instead of a general visible quartz probe, a probe 22 with good infrared transmission efficiency, that is, an infrared probe 22 as shown in FIG. Is used.

Infrared probe The infrared probe 22 shown in the figure includes a tapered core 44, a light-shielding metal film 46 as a mask, and a minute opening 48 as a tip of the tapered core.
The tapered core 44 is capable of transmitting infrared light with high efficiency. During the transmission, the tapered core 44 performs infrared infrared analysis of the scattered light 20 from the sample 12 by the near-field optical microscope 10 shown in FIG. The tip portion of the core of the optical fiber made of a material that does not generate noise or the like is sharpened by, for example, chemical etching, mechanical polishing, thermal pulling, or the like.

As an optical fiber material most suitable for such infrared near-field optics, for example, one or more selected from the group consisting of chalcogenite, fluoride such as calcium fluoride (CaF ₂ ), silver halide, and the like. Material is used.
The light-shielding metal film 46 is made of, for example, aluminum (Al), gold (Au), chromium (Cr), silver (Ag), germanium (Ge) or the like on the surface of the tapered core 44 except for the tip. A metal film made of one or more materials selected from the group is formed by one or more methods selected from the group consisting of coating, vapor deposition, plating, and the like.

This prevents light other than the scattered light 20 from entering from the outside.
The minute opening 48 is formed by forming a metal film 46 on the surface of the tapered core 44 except for its tip.
Alternatively, the minute opening 48 is also formed by selectively removing the tip of the metal film 46 after forming the metal film 46 over the entire circumference of the surface of the tapered core 44.

In the near-field optical microscope 10 according to the present embodiment, when the scattered light 20 from the sample 12 enters the infrared probe 22 through the minute aperture 48, the light can be transmitted with very high efficiency. It is sent to the spectrometer 38 by a fiber.
In this way, for example, when the base diameter dF of the projecting portion of the tapered core 44 is 30 nm, the opening diameter d is 20 nm, and the core sharp angle θ is 20 °, the near-field optical microscope 10 performs infrared spectroscopic analysis. The protruding infrared probe 22 having a preferable high infrared transmission efficiency is produced.
Here, if it is only necessary to grasp the surface shape of the measurement 12 with a general near-field optical microscope, the probe only has to scatter the near-field light 18. Of course, any can be used.

However, since the near-field optical microscope 10 using the infrared probe 22 according to the present embodiment also performs infrared spectroscopic analysis of the sample 12, a spectrum width that can be taken is necessary.
For this reason, when the probe is made of pure quartz, there is no problem in the visible region, but the transmission efficiency in the infrared region is not satisfactory.
Therefore, in the infrared probe 22 according to the present embodiment, the taper core 44 is made of chalcogenite, fluoride such as calcium fluoride (CaF ₂ ), silver halide, or the like, instead of general pure quartz. That is, in particular, when performing infrared spectroscopic analysis with the near-field optical microscope 10 appropriately, one or more materials are selected from the group consisting of materials having good infrared transparency.

Then, the infrared probe 22 according to the present embodiment enters the near-field light 18 field of the sample 12 and scatters the near-field light 18.
Thus, the scattered light 20 generated when the infrared probe 22 according to the present embodiment enters the field of the near-field light 18 enters the infrared probe 22 through the minute opening 48 and has high infrared transmission efficiency. Since it is transmitted, it is dispersed by one spectroscopic device 38 selected from the group consisting of FTIR, variable wavelength infrared laser spectrometer, free electron laser spectrometer, etc. 12 spectroscopic analyzes will be performed appropriately.

As described above, according to the infrared probe 22 according to the present embodiment, as a material of the tapered core 44, chalcogenite, calcium fluoride (particularly suitable for performing infrared spectroscopic analysis with the near-field optical microscope 10). Fluoride such as CaF ₂ ), silver halide, etc. are selected from other materials as well as a number of materials having infrared transparency, so compared with the case of using other materials, The near-field optical microscope 10 according to this embodiment can grasp the surface shape of the sample 12 in the infrared region and simultaneously measure the components with high efficiency.

According to the near-field optical microscope 10 using the infrared probe 22 according to the present embodiment, it is very difficult for a general microinfrared spectroscopic device to be near a minute aperture whose size is equal to or less than a wavelength. By using localized near-field light for irradiation or condensing, or by narrowing the near-field light for irradiation or condensing with a small aperture, infrared spectroscopy with a spatial resolution below the wavelength, independent of wavelength. Analysis can be performed.
In the configuration described above, an example in which a protruding type probe is used as the probe 22 has been described. However, the probe of the present invention is not limited to this. Any type can be used as long as the analysis can be appropriately performed by infrared spectroscopic analysis.

Therefore, in the above configuration, an example in which the light-shielding metal film 46 is formed on the surface of the tapered core 44 for the purpose of preventing light other than the scattered light 20 from the sample 12 from entering from the outside will be described. However, as long as the above various measurements can be performed appropriately, it is possible to use one that does not form the light-shielding metal film 46.
Further, when quartz is used as the material of the optical fiber, quartz is not used alone, and one or two or more selected from the group consisting of chalcogenite, fluoride, and silver halide, which are characteristic in this embodiment, are necessarily used. It is preferable to combine with a material.

Moreover, in the said structure, although the example of the near field optical microscope which operate | moves by c mode was demonstrated, the infrared probe concerning this invention is not limited to this, The near field optical microscope which operate | moves by i mode is used. Can also be applied.
Furthermore, the near-field optical microscope using the infrared probe 22 according to the present embodiment is not limited to the position control between the probe and the sample by the isolation information acquisition means 26 shown in FIG. It is also possible to use position control between samples.

Atomic Force Microscope Probe FIGS. 3 to 4 show a schematic configuration of an atomic force microscope probe according to an embodiment of the present invention.
2A is a schematic perspective view of the probe, and FIG. 2B is a longitudinal sectional view in the vicinity of the tapered core.
The atomic force microscope probe 50 shown in the figure is used as a base material for scanning the sample surface while keeping the distance to the measurement sample surface constant by the atomic force between the sample and the sample surface. A plate-like material 52 and a tapered core 54 are included.

Here, as the plate-like material 52, one or two or more selected from the group consisting of a quartz plate, a fluoride plate, a chalcogenite plate, and a silicon plate having good transmittance in the ultraviolet, visible, or infrared region. A material can be used.
As shown in FIG. 3, the plate-like material 52 is doped with an etching resistance material that forms the tapered core 54 by an operation such as a chemical etching method described later.
Alternatively, the etching resistance material is applied to a part of the surface of the plate-like material 52 as shown in FIG.

In other words, in the desired wavelength region such as visible, ultraviolet, infrared, etc., the dissolution rate ratio with respect to the plate-like material 52 is considered so as to be sharpened by performing a chemical etching method with a material having good transmission efficiency. Etching resistance material is used.
The etching resistance material is selected from the group consisting of germanium oxide (GeO ₂ ), lanthanoids, actinides, alumina, aluminum (Al), gold (Au), silver (Ag), silicon oxide (SiO ₂ ), and the like. Alternatively, two or more materials can be used.
In this way, the cantilever probe 50 of the atomic force microscope according to the present embodiment can be created.

Here, conventional atomic force microscope probes are manufactured using silicon semiconductor stacking technology, and there are problems that require expensive equipment and complicated processes. If the probe of the microscope is made of silicon, the probe only needs to obtain an atomic force between the sample and the sample so long as the surface shape of the sample can be grasped. Of course, any can be used.
However, in order to perform analysis of components and the like with an atomic force microscope, in order to perform spectroscopic analysis in the visible, ultraviolet, infrared region, etc., if the probe is made of silicon, visible, ultraviolet, infrared light is There was a fatal problem that the silicon could not be transmitted and could not be used.

Therefore, according to the probe 50 of the atomic force microscope according to the present embodiment, instead of general silicon, for example, germanium oxide (GeO ₂ ), aluminum (Al), gold (Au), silver (Ag), oxidation One or two selected from the group consisting of silicon (SiO ₂ ) and the like, that is, from the group consisting of materials having good transmission efficiency in the visible, ultraviolet and infrared regions, particularly suitable for spectroscopic analysis with an atomic force microscope The etching resistance material made of the above material is doped inside the plate-like material 52 or applied to a part of the surface thereof, and the etching resistance material is sharpened by, for example, a chemical etching method or the like to form a probe.

  Therefore, the tip of the tapered core 54 is moved up and down via the plate member 52 so that the value of the atomic force between the surface of the sample and the probe 50 according to the present embodiment and the sample is constant. If the surface of the sample is scanned, it becomes possible to accurately grasp the unevenness of the sample without contact with the sample, and the visible force from the sample can be obtained by the probe 50 of the atomic force microscope according to the present embodiment. Captures light in a desired wavelength region such as infrared, ultraviolet, and the like, and the captured light can be transmitted with high efficiency with almost no loss during transmission. In addition, for example, from the Raman spectrum or the like, it is possible to appropriately analyze the components and the like.

As described above, according to the probe 50 of the atomic force microscope according to the present embodiment, for example, germanium oxide (GeO ₂ ), aluminum (Al), gold (Au), silver (Ag), silicon oxide (SiO ₂ ). A group consisting of one or more materials selected from the group consisting of materials having good transmission efficiency in the visible, ultraviolet and infrared regions, particularly suitable for performing spectroscopic analysis with an atomic force microscope Since the etching resistance material is made into a probe, in addition to grasping the surface shape of the measurement sample, light from the sample can be captured and lost with high efficiency in the desired wavelength range such as visible, ultraviolet, and infrared. Therefore, near-field spectroscopic analysis can be performed well.

Further, according to the probe 50 of the atomic force microscope according to the present embodiment, by first creating a block doped with an etching resistance material therein, by cutting out the plate-like material 52 from this block, The material can also be prepared.
Further, since the etching resistance material is sharpened only once by chemical etching or the like, it can be mass-produced.

The Raman probe Figure 5, a schematic configuration of a Raman probe 56 according to an embodiment of the present invention is shown.
In the present embodiment, a fiber probe of a near-field optical microscope operating in the collection mode is assumed as the Raman probe 56.
A Raman probe 56 shown in the figure includes a tapered core 58 made of a grating fiber, a light-shielding metal film 60 as a mask, and a minute opening 62 as a tip portion of the tapered core 58.

The grating fiber is designed to have a bandwidth of 0.1 nm, for example, so that only the Rayleigh scattered light from the sample surface can be removed.
This grating fiber is probed at its tip.
That is, the light-shielding metal film 60 is formed by depositing a metal film made of one or more materials selected from the group consisting of aluminum (Al), gold (Au), and the like on the surface of the tapered core 58, Alternatively, it is formed by plating or coating.
The minute opening 62 is formed by selectively removing a light-shielding metal film portion formed at the tip of the tapered core 58.

Alternatively, the minute opening 62 is formed on the surface of the tapered core 58 in advance, except for the tip thereof, for example, one or more materials selected from the group consisting of aluminum (Al), gold (Au), and the like. It is formed also by vapor-depositing, plating, coating, or the like.
In this way, for example, only the Rayleigh scattered light from the sample surface is captured almost simultaneously from the microscopic aperture 62 at the root diameter dF = 30 nm of the protrusion, the opening diameter d = 20 nm, the acute angle θ of the core = 90 °, for example. Thus, the Raman probe 56 of the near-field optical microscope in which the bandwidth of the grating fiber is designed to be 0.1 nm or the like can be created.

Here, if only the surface shape of the measurement sample is to be grasped, the probe only needs to scatter the near-field light on the sample surface, and therefore any material can be used.
However, when Raman scattered light is collected by a probe as in this embodiment and near-field spectroscopy is performed, in addition to Raman scattered light, Rayleigh scattered light is also introduced into the probe as scattered light from the sample. However, due to the Rayleigh scattered light, the fiber itself generates Raman scattered light, which is superimposed on the Raman scattered light from the sample, and is notable for various emission spectroscopic analyzes such as Raman spectroscopy, fluorescence spectroscopy, and photoluminescence spectroscopy of the sample itself. Hinder.

Therefore, in order to appropriately obtain the Raman spectrum information of the sample, it is necessary to remove the Rayleigh scattered light as much as possible.
Therefore, the Raman probe 56 according to the present embodiment uses a grating fiber with a bandwidth designed so that the Rayleigh scattered light from the sample surface can be selectively removed as the material of the tapered core 58. It is used and the tip is probed.

Then, by scanning the surface of the sample while moving the tip of the fiber probe up and down with a near-field optical microscope using the Raman probe 56 according to the present embodiment so that the intensity of scattered light from the sample is constant. It is possible to accurately grasp the unevenness of the sample in a non-contact manner with the sample, and at the same time as the capture by the microscopic aperture 62, the Rayleigh scattered light is greatly reduced, so that the Raman scattered light generated by the optical fiber itself can be greatly reduced.
Thereby, in the desired wavelength region such as visible, infrared, and ultraviolet, substantially only the Raman scattered light from the sample can be spectroscopically analyzed, so that the components and the like can be appropriately analyzed.

As described above, according to the Raman probe 56 according to the present embodiment, the Rayleigh scattered light out of the scattered light from the sample surface is substantially intruded by the grating of the grating fiber acting as a rejection filter. Removed at the same time.
Therefore, the Raman scattered light generated by the optical fiber itself due to the Rayleigh scattered light can be completely removed or significantly reduced.
Thereby, it is possible to perform spectroscopic measurement for substantially only the Raman scattered light from the sample surface.
In the above configuration, a mask excluding the tip is formed on the tapered core surface with a metallic film made of one or more materials selected from the group consisting of aluminum, gold, silver, germanium, and chromium. However, the near-field optical probe of the present invention is not limited to this, and a mask may be formed so as to cover the entire core.

Infrared Probe FIG. 6 shows a process for producing an infrared probe according to this embodiment.
In the method shown in the figure, first, an optical fiber 64 made of chalcogenite is used as a flat-headed optical fiber as shown in FIG.
And in order to sharpen the end surface of such an optical fiber 64, the chemical etching process using etching liquid, such as nitric acid, hydrochloric acid, an alkali, aqua regia, is performed.
That is, when one end surface of the optical fiber 64 is cut and immersed in the etching solution for 1 hour, the root diameter dF of the protruding portion is 30 nm and the opening diameter due to the difference in the dissolution rate ratio with respect to the central portion of the peripheral portion. When d is 20 nm and the acute angle θ of the core is 20 °, a tapered core 44 as shown in FIG.

Then, by applying gold to the surface of the tapered core 44 by vapor deposition / sputtering, a mask made of a light-shielding metal film 46 as shown in FIG.
Then, by selectively removing the portion of the light-shielding metal film 46 covering the tip portion of the tapered core, the tip portion of the tapered core as the minute opening 48 as shown in FIG. Is exposed to the outside from the metal film 46.
If the infrared probe 22 prepared in this way is used, the infrared transmission efficiency is high, so that the scattered light from the sample in the infrared region for analyzing the component and the like as well as grasping the surface shape of the sample. Can be captured and transmitted with high efficiency.

FIG. 7 shows transmission when infrared rays having a wavelength of 2.5 μm to 11 μm are incident on an infrared probe 22 made of chalcogenite and a conventional fiber probe made of pure quartz having the same shape according to an embodiment of the present invention. Loss is shown.
As is apparent from FIG. 8, it is understood that FIG. I showing the present embodiment has very little infrared transmission loss in the wave number region as compared with FIG. II showing the conventional example.

  Therefore, according to the infrared probe according to the present embodiment, high infrared transmission efficiency can be obtained in a wide infrared region as compared with the conventional quartz probe. Since the scattered light from the sample necessary for the analysis can be obtained with high efficiency in the infrared region, the width of the obtained infrared spectrum is widened, and the subsequent spectroscopic analysis can be appropriately performed.

Atomic Force Microscope Probe FIG. 8 shows a process (No. 1) of creating an atomic force microscope probe according to this example.
In the method shown in the figure, a part of the inside of a plate-like material 52 made of a quartz plate as shown in FIG. 10A is formed into a cylindrical shape made of germanium oxide as shown in FIG. The etching resistance material 66 is doped.
Next, the etching resistance material 66 is sharpened by chemical etching with an etchant.

That is, when the plate-like material 52 doped with the etching resistance material 66 is immersed in an etching solution for 1 hour, the sharp angle of the core is 20 due to the difference in the dissolution rate ratio of the etching resistance material 66 to the plate-like material 52. By forming the taper core 44 with an angle of °, a cantilever probe 50 of an atomic force microscope as shown in FIG.
FIG. 9 shows a process (part 2) of creating an atomic force microscope probe according to this example.
In the method shown in the figure, the etching resistance material 66 is vapor-deposited on a part of the surface of a plate-like material 52 made of a quartz plate as shown in the figure (a), as shown in the figure (b).・ Apply by sputtering.

Next, the etching resistance material 66 is sharpened by chemical etching with an etchant.
That is, when the plate-like material having the etching resistance material applied to a part of the surface is immersed in an etching solution for 1 hour, the tip of the core is caused by the difference in the dissolution rate ratio of the etching resistance material 66 to the plate-like material 52. By forming the tapered core 44 having an acute angle θ of 20 °, a cantilever probe 50 for an atomic force microscope as shown in FIG.

By using an atomic force microscope probe created in this way, high transmission efficiency in the desired wavelength region such as visible, ultraviolet, and infrared can be obtained. It is possible to perform spectroscopic analysis such as visible, ultraviolet, and infrared.
FIG. 10 shows a case where infrared rays having a wavelength of 2.5 μm to 11 μm are incident on a probe 50 having a fluoride (CaF ₂ ) core and a conventional silicon probe having the same shape according to an embodiment of the present invention. The transmissivity of is shown.
As is clear from FIG. 6, it is understood that FIG. I showing the present embodiment has an extremely high infrared transmittance in the wave number region as compared with FIG. II showing the conventional example.

  Therefore, according to the probe 50 for atomic force microscope according to the present embodiment, a high infrared transmission efficiency can be obtained as compared with the conventional silicon probe. Since the Raman scattered light from the sample necessary for analysis such as the above can be obtained with high efficiency in the infrared region, the width of the obtained infrared spectrum is widened and the subsequent spectroscopic analysis can be performed properly. Become.

Raman Probe FIG. 11 shows a process of creating a Raman probe according to this example.
In the method shown in the figure, first, a flat-headed grating fiber as shown in FIG. 10A, whose bandwidth is designed to be 0.1 nm so that the Rayleigh scattered light from the sample can be removed. 68 is used.
Then, in order to sharpen the end face of the grating fiber 68, a chemical etching process using an etching solution is performed.

That is, when one end of the grating fiber 68 is cut and immersed in an etching solution for 1 hour, the root diameter dF of the protruding portion is 30 nm and the opening diameter d is 20 nm due to the difference in the dissolution rate ratio with respect to the peripheral portion of the central portion. When the core has a sharp angle θ = 20 ° and a sharp angle of 20 °, a tapered core 58 as shown in FIG.
Then, by applying a metal film such as gold on the surface of the tapered core 58 by vapor deposition / sputtering, a light-shielding metal film 60 shown in FIG.
Then, by selectively removing the portion of the light-shielding metal film 60 that covers the tip of the tapered core 58, the tip of the tapered core as the minute opening 62 is formed as shown in FIG. The metal film 60 is exposed to the outside.

By using the Raman probe 56 thus prepared, the Rayleigh scattered light is prevented from being sent through the optical fiber by the grating fiber 68 from the measurement sample entering the probe tip. Thus, the influence of the Raman light generated by the optical fiber itself can be greatly reduced, and only the Raman light from the measurement sample can be obtained.
As a result, various emission spectroscopic analyzes such as Raman spectroscopy, fluorescence spectroscopy, photoluminescence spectroscopy, etc. in the desired wavelength range such as visible, ultraviolet, infrared, etc. are performed to understand the surface shape of the sample and analyze its components. It can be done properly.

It is explanatory drawing of schematic structure of the near-field optical microscope concerning one Embodiment of this invention. It is explanatory drawing of schematic structure of the infrared probe concerning one Embodiment of this invention. , It is explanatory drawing of schematic structure of the probe for atomic force microscopes concerning one Embodiment of this invention. It is explanatory drawing of schematic structure of the probe for Raman concerning one Embodiment of this invention. It is explanatory drawing of the creation process of the probe for infrared rays concerning one Example of this invention. It is explanatory drawing of the comparison result of the infrared transmissivity (infrared transmission loss) at the time of using the infrared probe concerning one Example of this invention, and the conventional quartz probe. , It is explanatory drawing of the creation process of the probe for atomic force microscopes concerning one Example of this invention. It is explanatory drawing of the comparison result of the infrared transmittance (infrared transmittance) at the time of using the probe for atomic force microscopes concerning one Example of this invention, and the conventional silicon probe. It is explanatory drawing of the creation process of the probe for Raman concerning one Example of this invention.

Explanation of symbols

10: Near-field optical microscope 22 ... Infrared probe (infrared near-field optical probe)
38 ... Spectroscope (spectrometer)
56 ... Raman probe (Raman near-field optical probe)
44, 54, 58 ... Tapered core 46, 60 ... Light-shielding metal film (mask)
48, 62 ... minute opening (tip)
50 ... Probe for atomic force microscope 52 ... Plate material (base material)

Claims (4)

A substrate for scanning the surface of the sample while keeping the distance from the surface of the measurement sample constant;
An etching resistance material made of a material having a good transmission efficiency in a desired wavelength region and a material in which a dissolution rate ratio with respect to the base material is sharpened so as to be sharpened with respect to the base material by a chemical etching method. A tapered core obtained by doping or coating a material and sharpening the etching resistance material;
For an atomic force microscope characterized by being able to irradiate a measurement sample with incident light in a desired wavelength range or capture scattered near-field light from the measurement sample from the tip of the tapered core. probe. In the atomic force microscope probe according to claim 1,
An atomic force microscope probe characterized in that one or two or more plate members selected from the group consisting of a quartz plate, a fluoride plate, a chalcogenite plate, and a silicon plate are used as the substrate. The probe for an atomic force microscope according to claim 1 or 2, wherein the etching resistance material is one or more selected from the group consisting of germanium oxide, lanthanoid, actinoid, alumina, aluminum, gold, silver, and silicon oxide. A probe for an atomic force microscope, characterized in that it is made of any material. The near-field optical probe according to any one of claims 1 to 3,
On the tapered core surface, a mask excluding the tip or a mask covering the entire core with a metallic film made of one or more materials selected from the group consisting of aluminum, gold, silver, germanium and chromium A near-field optical probe characterized in that is formed.

Images