JP2007315963A - Optical fiber probe and manufacturing method, inspecting apparatus and inspecting method of the optical fiber probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an optical fiber probe with a large working distance to a scan by a regular travel light spot. <P>SOLUTION: A core of a single-mode optical fiber FV is provided with a conical near-field light exudation face, having a first taper angle: α, and a conical regular travel light exit face, coaxially surrounding the near-field light exudation face and having a second tapered angle: β. A conductive thin film 120 is formed on the near-field light exudation face so as to implement a near-field light exudation. A cladding section 103 has a solution speed with respect to an etching liquid, which is higher than that of the core. The core is provided with first and second cores 101, 102 disposed coaxially and having different solution speeds. The near-field light exudation face 110 is formed in the first core 101, and the regular travel light exit face 112 is formed in the second core 102 by a selective (chemical) etching process; and the second tapered angle: β is more than 50° and less than 90°. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical fiber probe, an optical fiber probe manufacturing method, an inspection apparatus, and an inspection method.

  It is known that a near-field light spot is formed by evanescent light exuding from an optical probe, and the surface of the object is inspected by scanning the surface of the object, or the surface is processed by light energy. As an optical probe for forming a light spot, one in which a “conical shape with a small apex angle” is formed on the emission end face of an optical fiber for leaching near-field light is known (Patent Documents 1 to 3, etc.).

  The optical probe can also be used to irradiate an object with “totally reflected light” to generate evanescent light on the surface of the object, which is disturbed and detected by the conical portion.

  The near-field light spot formed by the optical probe is formed very close to the tip of the conical surface, and evanescent light generated on the object surface is also very close to the object surface. Accordingly, the conical portion of the optical probe is moved very close to the object surface both when scanning with a near-field light spot and when detecting evanescent light in a disturbed manner.

Since there are microscopic irregularities and undulations on the scanned object surface, if the tip of the optical probe does not follow the surface shape well during scanning, the conical part of the tip of the optical probe will come into contact with the object surface. The conical part is easily damaged. For this reason, the above scanning must be performed at a “slow scanning speed”, and it takes a long time to scan a small inspection region.
Patent Document 4 discloses a normal optical microscope apparatus including an observation system using an objective lens in which a near-field light detection optical probe is incorporated.

  In this apparatus, first, a wide surface area of an object is observed with an objective lens to identify a “surface area to be observed with a near-field light spot”, and “scanning with a near-field light spot” is performed on the identified surface area. Although the area observed by the objective lens is an area of the order of several hundred μm at most, the inspection area by the near-field light spot is an area of the order of 0.1 μm at most, and the magnification difference between them is an order of 1000 times. In addition, it is not always easy to access the optical probe to the “surface region to be observed by the near-field light spot” identified through observation by the objective lens, and it is difficult to access in a short time.

  A "conical portion with a large apex angle" is formed coaxially on the outer periphery of the "conical portion with a small apex angle" at the tip of the optical probe by an optical fiber, and the normal propagation light from the "conical portion with a large apex angle" A "normally propagated light spot" is formed at a position away from the tip of the optical probe, and the object surface is selectively selected from a low resolution inspection using a normal propagation light spot and a high resolution inspection using a near-field light spot. Prior to high-resolution inspection with a near-field light spot, a low-resolution scan with a normal propagation light spot is performed, and based on the results, a "region to be scanned with a near-field light spot" is identified and high-resolution It is intended to perform a scan.

  In this method, both the near-field light spot and the normal propagation light spot are formed by the same optical probe, so the optical probe is set to the “surface region to be scanned by the near-field light spot” specified through low-resolution scanning. It is easy to do.

  In order to efficiently perform low-resolution scanning with a normal propagation light spot, it is necessary to perform low-resolution scanning at high speed, and such high-speed scanning ensures “non-contact between the tip of the optical probe and the object surface”. For this purpose, it is important that the “working distance” of the low resolution scanning by the normal propagation light spot is large, that is, the normal propagation light spot is formed sufficiently away from the tip of the optical probe.

  On the other hand, in the case of scanning with a near-field light spot, the aspect ratio of the tip of the optical probe, that is, the amount of protrusion from the outermost periphery of the optical probe at the tip portion of the “cone shape with a small apex angle” that exudes near-field light: h And the ratio of the optical probe radius: r: the tangent angle given by h / r: ξ (tan ξ = h / r), and the small unevenness of the surface of the object to be scanned, the magnitude of the undulation slope becomes a problem.

  In other words, since the high-resolution scanning by the near-field light spot is performed by displacing the tip of the optical probe to “slipping the object surface”, the locus of the tip of the optical probe on the scanning line is substantially the same as the profile of the object surface on the scanning line. However, if there is a part where the inclination angle η of the profile is larger than the aspect ratio ξ, that is, “a part where the inclination of the profile is stronger than the aspect ratio”, the outer periphery of the optical probe contacts the object surface, and the near field Scanning with a light spot may be limited.

JP-A-10-82791 JP-A-11-23587 JP 2001-66240 A JP 2000-55818 A

The present invention has been made in view of the above-described circumstances, and an object thereof is to realize an optical fiber probe having a large working distance with respect to low resolution scanning by a normal propagation light spot.
Another object of the present invention is to realize an optical fiber probe having a large working distance with respect to scanning by a normal propagation light spot and a large aspect ratio of the probe tip.

  Another object is to realize a method for manufacturing the optical fiber probe with high accuracy according to design conditions, and to realize an inspection apparatus and inspection method using the optical fiber probe.

  The optical fiber probe of the present invention is an optical probe used for “a light inspection in which a low-resolution inspection using a normal propagation light spot and a high-resolution inspection using a near-field light spot” are performed.

  In this specification, “inspection” means that the state of the test surface is optically scanned to “optically observe the state of the test surface” or “optically measure the test surface”. The case further includes a case of “processing the surface to be measured with light energy”. The “test surface” is a surface to be subjected to the above-described optical measurement and processing, and an object having this test surface is referred to as “subject”.

  “Optical inspection” is to obtain optical information of the test surface (transmitted light, reflected light, intensity of light that disturbs evanescent light generated on the test surface, spectrum, polarization state, etc.). . Through optical inspection, it is possible to know the surface shape of the test surface and the optical physical properties of the test object.

  The optical fiber probe according to claim 1 is a conical shape having a first taper angle: α at a core portion of one end face of a single mode optical fiber having a core portion for propagating light and a clad portion surrounding the core portion. At least near-field light, and a conical-shaped normal propagation light exit surface having a second taper angle: β (> α) surrounding the near-field light exudation surface coaxially. A conductive thin film for leaching near-field light is formed on the bleed surface.

  The taper angle of the near-field light exudation surface: α is ½ of the apex angle of the conical shape forming the near-field light exudation surface. Similarly, the taper angle β of the normal propagation light exit surface is ½ of the apex angle of the conical shape forming the normal propagation light exit surface.

  The cladding portion has a “dissolution rate with respect to the etching solution” larger than that of the core portion, and the core portion has a first core and a second core that have different “dissolution rates with respect to the etching solution” and are selective (chemical) etching. As a result, a near-field light extruding surface is formed on the first core, and a normal propagation light emitting surface is formed on the second core.

  That is, in the optical fiber probe according to the first aspect, the “near-field light bleed surface” has a first taper angle: α, that is, an apex angle: on the first core at the center of the core portion at one end of the single mode optical fiber. A “normal propagation light exit surface” is formed in a conical shape with a second taper angle: β, that is, an apex angle: 2.β, so as to surround the 2 · α conical shape and surround the conical shape. ing. The normal propagation light exit surface and the near-field light exudation surface are coaxial and share a conical axis. In other words, the near-field light extruding surface is “protruded into a pointed conical shape” from a portion of the cone-shaped normal propagation light emitting surface having a gentle slope, which is close to the conical axis.

Second taper angle: β (degrees) is
50 <β <90
It is in the range.

  The “conductive thin film for near-field light exudation” formed on at least the near-field light exudation surface may be formed only on the near-field light exudation surface, or the normal propagation light exit surface in addition to the near-field light exudation surface May be formed on a part of or the entire surface, or on the cladding.

  If the conductive thin film is formed only on the near-field light bleed surface, the conductive thin film is formed with a light-shielding property so that the near-field light oozes easily. Further, when it is also formed on the normal propagation light exit surface, the transmittance with respect to the normal propagation light is set to a necessary size so as not to prevent the emission of the normal propagation light.

  As will be described later, the wavelength of the light forming the near-field light spot is different from the wavelength of the light forming the normal propagation light spot, and the transmittance of the conductive thin film is changed to the wavelength for the near-field light spot. In contrast, the conductive thin film can be formed not only on the near-field light exudation surface but also on the normal propagation light exit surface. The propagating light can be normally emitted regardless of the presence of the conductive thin film.

  The “conductive thin film for leaching near-field light” is formed at least on the near-field light bleed surface, but the conductive thin film is formed so that the conical tip forming the near-field light bleed surface is covered. The case where it forms, and the case where it forms so that a conductive thin film is not formed in the said front-end | tip part but "a front-end | tip part is exposed" are included.

  An optical fiber probe according to a second aspect is the optical fiber probe according to the first aspect, wherein the normal propagation light exit surface has an “inclined surface having a taper angle: γ (<90 degrees)” on the outer peripheral side. The inclined surface having the taper angle: γ is a conical surface, and the taper angle: γ is ½ of the apex angle of the conical surface.

In the optical fiber probe according to claim 2, the “inclined surface having taper angle: γ” is formed by forming “taper angle: γ1 larger than β” as the taper angle: γ on the outer peripheral portion of the normal propagation light exit surface in the second core. (Claim 3). That is, in this case, a normal propagation light exit surface having a taper angle: β is formed in the second core portion, and an inclined surface having a stronger slope than the normal propagation light exit surface is formed in a conical shape on the outer periphery thereof. Will be formed.
In the optical fiber probe according to claim 2 or 3, the “inclined surface having a taper angle: γ” can be “formed with a taper angle: γ2 as a taper angle: γ” in the clad portion (claim 4).
That is, in the case of this claim 4, “a conical shape portion with a taper angle: α, a conical shape portion with a taper angle: β, and a conical shape portion with a taper angle: γ1” are formed in the core portion; Furthermore, there is a mode in which a conical portion having a taper angle of γ2 is formed on the outer cladding portion. Of course, in any case, the taper angles α, β, γ1, and γ2 are smaller than 90 degrees.

  Therefore, in the optical fiber probes of claims 2, 3 and 4, the height from the outer periphery of the single mode optical fiber to the tip of the near-field light bleed surface increases, and the aspect ratio of the tip increases. Become.

  In the optical fiber probe according to any one of claims 1 to 4, the core portion and the clad portion of the single-mode optical fiber can be “having quartz glass as a base material” (claim 5).

An optical fiber probe according to a sixth aspect of the present invention is the core portion and the clad portion having the quartz glass as a base material according to the fifth aspect, wherein the core portion is “quartz glass doped with germanium dioxide (GeO ₂ )”. The addition amount of germanium dioxide is different between the first core and the second core, the addition amount in the first core is relatively large with respect to the addition amount in the second core, and these addition amounts are And the second core is selected so as to provide a “desired dissolution rate for the etching solution”. In this case, the cladding portion can be “pure silica glass (non-added silica glass)” to which germanium dioxide is not added (Claim 7), and the taper angle is formed on the outer peripheral portion of the normal propagation light exit surface in the second core. : An inclined surface of γ1 can be formed (claim 8).

  The optical fiber probe according to claim 6 can also include “quartz glass whose clad portion has been subjected to anhydrous chlorine treatment” (claim 9), and has a taper angle at the outer peripheral portion of the normal propagation light exit surface of the second core. : An inclined surface of γ1 can be formed (claim 10).

  The “cladding part” of the optical fiber probe according to claim 9 or 10 is composed of an “inner cladding part and an outer cladding part”, the inner cladding part is made of pure quartz glass, and the outer cladding part is “anhydrous” It can be made of an optical fiber probe composed of “chlorine-treated quartz glass” and having an inclined surface with a taper angle of γ2 formed in the inner clad part (claim 11).

The “taper angle of the normal propagation light exit surface: β (degrees)” in the optical fiber probe according to any one of claims 1 to 11,
60 ≦ β ≦ 80
More preferably, it is in the range (claim 12).

  The optical fiber probe according to any one of claims 1 to 12, wherein "the subject is irradiated with totally reflected light, and the evanescent light generated on the subject surface is disturbed at the conical portion formed by the near-field light exudating surface. Of course, it can also be used for “detection”.

  The optical fiber probe as described above can be manufactured by the manufacturing method according to claim 13, for example.

  That is, as a single mode optical fiber, “the addition amount of germanium dioxide is adjusted so that the addition amount in the first core is relatively higher than the addition amount in the second core, and the aqueous ammonium fluoride solution, hydrofluoric acid, and water are adjusted. Using a single mode optical fiber whose dissolution rate with respect to the etching solution is reduced in the order of the cladding part, the second core, and the first core, and the etching process and the conductive thin film forming process are performed on the end surface of the single mode optical fiber. It can be manufactured by doing.

  In the “etching step”, the end face of the single mode optical fiber is immersed in an “etching solution composed of an aqueous ammonium fluoride solution, hydrofluoric acid and water” to perform selective (chemical) etching, and a first taper angle is formed on the first core. : A near-field light extruding surface having α, and a normal propagation light emitting surface having a second taper angle: β on the second core.

  When the dissolution rates of the first core, the second core, and the cladding are R1, R2, and R3, the taper angle: α is given by sin α = R1 / R3, and the taper angle is obtained by adjusting the dissolution rates: R1 and R3. : Α can be adjusted. The taper angle: β is given by sin β = R2 / R3, and the taper angle: β can be adjusted by adjusting the dissolution rate: R2 and R3.

  “Conductive thin film formation process” forms “conductive thin film for leaching near-field light” on at least the near-field light bleed surface of the near-field light bleed surface and normal propagation light exit surface formed in the etching process. It is a process to do.

The optical fiber probe as described above can also be manufactured by the manufacturing method according to claim 14, for example.
That is, as a single mode optical fiber, “germanium dioxide is added to the first core and the second core of the core portion so that the amount of the first core added is relatively higher than the amount of the second core added. , A single mode optical fiber whose dissolution rate with respect to an etching solution composed of an aqueous ammonium fluoride solution, hydrofluoric acid and water decreases in the order of the cladding portion, the second core, and the first core ”. First and second etching steps and a conductive thin film forming step are performed.

  The “first etching step” is a step of forming an inclined surface in the core part by immersing the end surface of the single mode optical fiber in “a first etching solution having a relatively low mixing ratio of the ammonium fluoride aqueous solution”.

  In the “second etching step”, the end surface of the single mode optical fiber having the inclined surface formed in the core portion by the first etching step is immersed in the “second etching solution having a relatively high mixing ratio of the ammonium fluoride aqueous solution”. And a normal-propagation light exit surface having a first taper angle: α and a normal-propagation light emission surface having a second taper angle: β, and an inclination angle at an outer peripheral portion of the normal-propagation light emission surface of the second core : A step of forming an inclined surface having γ1.

  In the “conductive thin film forming step”, a conductive thin film for leaching near-field light is formed on at least the near-field light bleed surface of the near-field light bleed surface and the normal propagation light exit surface formed in the second etching step. It is a process of forming.

The “conductive thin film forming step” in the manufacturing method according to claims 13 and 14 can be performed by a known appropriate film forming technique such as vapor deposition or sputtering.
As described above, the “conductive thin film for near-field light exudation” may be formed only on the near-field light exudation surface, or may include a part or the whole of the normal propagation light exit surface including the near-field light exudation surface, May be formed on the clad part, so as to cover the tip part of the conical part forming the near-field light bleed surface, and no conductive thin film is formed on the tip part of the conical part. It may be.

  When forming a conductive thin film only on the near-field light bleed surface, for example, a conductive thin film is formed on the end surface of the single mode optical fiber on which the near-field light bleed surface or the normal propagation light exit surface is formed. A mask that covers only the exudation surface is formed by “a technique such as photolithography”, and the conductive thin film that is not covered by the mask may be removed by etching. The “conductive thin film” can also be removed.

  Alternatively, a near-field light can be obtained by forming a mask on a surface other than the near-field light extruding surface, forming a conductive thin film by a deposition method such as vapor deposition or sputtering, and removing the conductive thin film formed on the mask together with the mask. A conductive thin film can be formed only on the exudation surface.

  In the method for manufacturing an optical fiber probe according to claim 14, the clad portion of the single mode optical fiber is subjected to an inner clad portion made of "pure quartz glass not subjected to anhydrous chlorine treatment" and "anhydrochlorinated treatment. It is possible to form an inclined surface having a taper angle of γ2 in the inner cladding portion by the first and second etching steps.

  The optical fiber probe manufacturing method according to any one of claims 13 to 15, wherein the etching solution, the first etching solution, and the second etching solution are "concentration: 40 wt% ammonium fluoride aqueous solution and concentration: 50 wt%." It consists of hydrofluoric acid and water ”(claim 16). In this case, the second etching solution has a relatively high “concentration: mixing ratio of 40 wt% ammonium fluoride aqueous solution” compared to the first etching solution.

The inspection apparatus according to the present invention is an “inspection apparatus that optically scans and inspects a test surface of a subject” and includes a light source, an optical fiber probe, a scanning unit, and a detection processing unit. ).
The “light source” emits light for inspection.
“Optical fiber probe” is a single-mode optical fiber that propagates light from a light source and has a near-field light bleed surface and a normal-propagation light exit surface formed at the exit, and is formed at least on the near-field light bleed surface. And a conductive thin film for leaching near-field light, and any one of claims 1 to 12 is used.
The "scanning means" includes a low-resolution scan for low-resolution inspection using a normal propagation light spot formed by normal propagation light emitted from the normal propagation light exit surface of the optical fiber probe, and a near field that exudes from the near field light exudation surface. This is means for selectively performing high-resolution scanning for high-resolution inspection with a near-field light spot of light on the surface to be inspected.

The “detection processing unit” is a unit that detects inspection light through the surface to be detected and performs data processing.
The “light source” in the inspection apparatus according to claim 17 can selectively emit light of different wavelengths according to the low resolution inspection and the high resolution inspection (claim 18).

The inspection method according to the present invention is an “inspection method for optically scanning a test surface of a subject” and has the following characteristics.
That is, the light emitted from the light source is guided by the optical fiber probe according to any one of claims 1 to 12, and is normally formed by normal propagation light emitted from the normal propagation light emission surface of the optical fiber probe. Low-resolution scanning for low-resolution inspection using a propagating light spot and high-resolution scanning for high-resolution inspection using a near-field light spot leaching from the near-field light bleed surface are performed on the surface to be inspected by scanning means. The detection processing means detects the inspection light through the test surface and processes the data.
In the inspection method according to claim 19, it is possible to "selectively emit light of different wavelengths from the light source in accordance with the low resolution inspection and the high resolution inspection" (claim 20).

  In the above-described claims 17 and 19, the “detection light through the test surface” is light influenced by the state of the test surface, that is, the state of the test surface is optical information (reflected light intensity, transmitted light intensity, The evanescent light has a disturbed propagation light intensity, spectrum, polarization state, etc.).

  In addition, as shown in the embodiment described later, the optical fiber probe according to any one of claims 1 to 12 is provided on the normal propagation light emitting surface instead of forming a conductive thin film on the normal propagation light emitting surface. By switching the polarization film and adjusting the polarization state of the light from the light source using the “polarization control means”, the normal propagation light exit from the normal propagation light exit surface can be switched between the “emission state and the non-emission state”. it can.

  As described above, in the optical fiber probe of the present invention, the conical near-field light bleed surface having the first taper angle: α and the near-field light bleed surface are coaxially formed in the core portion of one end face of the single mode optical fiber. And a conical normal propagation light exit surface having a second taper angle: β (> α), and a conductive thin film for leaching near-field light is formed on at least the near-field light bleed surface. However, since the taper angle of the normal propagation light exit surface: β is “greater than 50 degrees and less than 90 degrees”, preferably “more than 60 degrees and less than 80 degrees”, the normal propagation light spot is changed to the tip of the optical fiber probe. Can be formed at a position that is sufficiently distant from the area, can achieve a “large working distance” with respect to scanning with a normal propagation light spot, Since the non-contact "of is secured, it is possible to efficiently perform a low resolution scan at high speed.

  In the optical fiber probe of claims 2 to 4, the height from the outer periphery of the single mode optical fiber constituting the optical fiber probe to the tip of the near-field light bleed surface is increased, and the aspect ratio of the tip of the optical fiber probe is increased. Since it becomes large, it is possible to perform good scanning with a near-field light spot even on a test surface having a larger inclination angle of the profile on the scanning line.

  Such an optical fiber probe can be easily and reliably manufactured by the manufacturing method of the present invention. And by the inspection method and inspection apparatus using the optical fiber probe of the present invention, high-resolution inspection using a near-field light spot can be performed quickly and easily.

Embodiments of the invention will be described below.
FIG. 1 is a diagram for explaining one embodiment of an optical fiber probe.
The optical fiber probe 100 is an optical fiber probe that is used for optical inspection that performs low-resolution inspection using a normal propagation light spot and high-resolution inspection using a near-field light spot. As shown in FIG. A probe portion PR is formed at one end of a single-mode optical fiber FV having a length. In addition, since the part connected to the probe part PR is etched by selective (chemical) etching, the diameter of the single mode optical fiber FV shown in FIG. Smaller than the diameter.

  FIG. 1A shows a “cross-sectional state by a plane orthogonal to the length direction” of a single mode optical fiber forming the optical fiber probe 100. The cross-sectional structure of the single mode optical fiber is centered on the first core 101, the second core 102 is formed surrounding the first core 101, and the cladding portion 103 is formed so as to surround the second core 102 outside thereof. Is formed. The first core 101 and the second core 102 constitute a “core part”. The cladding portion 103 has a higher dissolution rate with respect to the etching solution than the core portion, and the first core 101 and the second core 102 that are coaxially formed to form the core portion have different dissolution rates with respect to the etching solution.

  As shown in FIG. 1B, the probe portion PR formed at one end portion of the single mode optical fiber FV has a conical near-field light extruding surface 110 having a first taper angle: α and the near-field light. It has a conical normal propagation light exit surface 112 that coaxially surrounds the exudation surface 110 and has a second taper angle: β (> α).

  The near-field light extruding surface 110 and the normal propagation light emitting surface 112 are formed by selective (chemical) etching. In this selective (chemical) etching, the taper angle of the near-field light extruding surface 110: α, normal propagation light emission, depending on the ratio of the “dissolution rate with respect to the etching solution” of the first core 101, the second core 102, and the clad 103. The taper angle of the surface 112: β is determined.

  In FIG. 1B, reference numeral 120 denotes a “conductive thin film for leaching near-field light”. In this example, the conductive thin film 120 is formed at a “single-beam optical fiber end” including the probe portion PR. Yes.

  The normal propagation light exit surface 112 is set so that the second taper angle β is greater than 50 degrees and less than 90 degrees, and more preferably 60 degrees or more and 80 degrees or less. The “dissolution rate with respect to the etching solution” is set so as to realize the second taper angle having such a magnitude.

That is, the optical fiber probe 100 shown in the embodiment in FIG. 1 is an optical fiber probe used for optical inspection that performs low-resolution inspection using a normal propagation light spot and high-resolution inspection using a near-field light spot. The conical near-field light extruding surface 110 having a first taper angle: α is formed on the core portion of one end face of the single mode optical fiber having the core portions 101 and 102 for propagating light and the clad portion 103 surrounding the core portion. And a conical-shaped normal propagation light exit surface 112 having a second taper angle: β (> α) coaxially surrounding the near-field light exit surface 110 and at least close to the near-field light exit surface The conductive thin film 120 for leaching the field light is formed, and the cladding portion 103 has a higher dissolution rate with respect to the etching solution than the core portion, and the core portion has a dissolution rate with respect to the etching solution. The first core 101 and the second core 102 which are different from each other are coaxially formed, and by the selective (chemical) etching, the near-field light extruding surface 110 is emitted from the first core 101 and the normal propagation light is emitted from the second core 102. Each of the surfaces 112 is formed, and the second taper angle: β (degrees) is
100 <2β <180
(Claim 1).

  Here, “conductive thin film for leaching near-field light” will be described. As described above, this conductive thin film is formed on “at least the near-field light bleed surface” of the optical fiber probe. It may be formed only on the surface, or it may be formed on a part or all of the normal propagation light exit surface including the near-field light bleed surface, and further up to the cladding part, and the conical portion forming the near-field light bleed surface A conductive thin film may or may not be formed at the tip of the electrode.

  FIG. 2 shows a form of forming a “conductive thin film for leaching near-field light” formed at the end of a single mode optical fiber on which the near-field light bleed surface 110 and the normal propagation light exit surface 112 as shown in FIG. 1 are formed. Three examples are shown.

  The conductive thin film 120A shown in FIG. 2 (a) includes a near-field light extruding surface 110, a normal propagation light emitting surface 112, and an end surface of the clad portion 103, like the conductive thin film 120 of FIG. However, it is not formed at the tip portion of the near-field light bleed surface 110, and the "tip portion of the near-field light bleed surface is exposed" at this portion. That is, the conductive thin film 120A is “the thin film portion at the tip of the near-field light extruding surface 110 is removed” from the conductive thin film 120 shown in FIG.

  The conductive thin film 121 shown in FIG. 2B is formed only on the near-field light bleed surface 110. Also in this case, the tip portion may be exposed without forming a thin film at the tip portion of the near-field light extruding surface 110.

FIG. 2C shows an example in which a polarizing film 125 is provided on the normal propagation light exit surface 112 in addition to the conductive thin film 121 shown in FIG. When the polarizing film 125 is used, the normal state of the light from the light source is adjusted by the “polarization control means”, so that the normal propagation light exit from the normal propagation light exit surface 112 is switched between the “emission state and the non-emission state”. be able to. The conductive thin film 121 may not be formed at the distal end portion of the near-field light extruding surface 110 and the distal end portion may be exposed.
The polarizing film 125 may be formed up to the end surface or the peripheral surface of the cladding portion 103.
Since the “form of forming the conductive thin film” on the near-field light bleed surface is as described above, the conductive thin film and the polarizing film are not shown in the drawings according to the following description.

FIG. 3 is a diagram showing another embodiment of the optical fiber probe. In order to avoid confusion, the same reference numerals as in FIG.
A single-mode optical fiber serving as a base material surrounds a core portion composed of a first core 101 and a second core 102, and a cladding portion 103 is formed. The first core 101 has a cone having a first taper angle: α. A near-field light extruding surface 110 having a shape is formed, and a conical normal light emitting surface 112 having a second taper angle: β and an inclined surface having a taper angle: γ1 are formed on the second core 102 as a conical surface. Has been. The taper angle: γ1 is smaller than the taper angle: β.

  That is, the optical fiber probe shown in FIG. 3 has an inclined surface 113 having a taper angle: γ1 on the outer peripheral side of the normal propagation light exit surface 112 (claim 2). An inclined surface 113 having a taper angle: γ1 is formed on the outer peripheral portion of the normal propagation light exit surface 112 in the second core 102, and the taper angle: γ1 is smaller than the taper angle: β (claim 3).

  FIG. 4 is a diagram showing another embodiment of the optical fiber probe. In order to avoid confusion, the same symbols as in FIG.

As shown in FIG. 4A, the single mode optical fiber that is the base material of the optical fiber probe according to this embodiment has the second core 102 around the first core 101, An inner cladding portion 103A and an outer cladding portion 103B are provided on the outer periphery.
At the end of the single-mode optical fiber, a conical near-field light bleed surface 110 having a first taper angle: α is formed on the first core 101, and a second taper angle: β is formed on the second core 102. A normal propagation light exit surface 112 surrounding the near-field light extruding surface 110 and a conical inclined surface 113 having a taper angle: γ1 are formed, and a taper angle: A conical inclined surface 114 of γ2 is formed. That is, in the embodiment of FIG. 4, the inclined surface 114 having the taper angle: γ2 is formed in the clad portion (claim 4).

  FIG. 4B shows a state where the optical probe of FIG. 4A is viewed from below. As shown in the figure, the near-field light extruding surface 110, the normal propagation light emitting surface 112, the inclined surfaces 113 and 114, and the end surfaces of the outer cladding 103B are coaxial.

  Of course, also in the embodiment of FIG. 3 and FIG. 4, at least the near-field light exuding surface 110 is formed with the “conductive thin film for near-field light exudation” in the above-described form, and the “polarizing film” is optionally formed. Although formed as described above, these thin films are not shown.

FIG. 5 is a diagram for explaining the formation of the normal propagation light spot and the near-field light spot, taking the optical fiber probe 100 described with reference to FIG. 1 as an example.
When the light L from the light source is guided as normal propagation light in the single mode optical fiber of the optical fiber probe 100 and reaches the exit side end, the normal propagation light incident on the normal propagation light exit surface 112 is the normal propagation light. The light exits from the exit surface 112 as exit light LO. Since the normal propagation light exit surface 112 has a conical shape having a second taper angle: β, the exit light LO is refracted toward the cone axis side of the normal propagation light exit surface 112 and condensed on the cone axis. A normal propagation light spot SPO is formed. At this time, the distance WD between the normal propagation light spot SPO and the tip portion of the optical fiber probe is a working distance when the low resolution inspection is performed by the normal propagation light spot SPO.

  Working distance: WD depends on the wavelength of the normal propagation light, the refractive index of the core with respect to this wavelength, the second taper angle of the normal propagation light exit surface 112: β, and the conical shape of the near-field light extruding surface 110 Ratio of diameter: B and diameter of conical shape of normal propagation light exit surface 112: A: It depends also on B / A.

  As an example, when the refractive index with respect to the normal propagation light of the core part forming the normal propagation light exit surface is 1.53 and the exit side is air, the inner peripheral side end of the normal propagation light exit surface and the normal propagation light spot FIG. 7A shows how the distance D in the conical axis direction changes with the inclination angle θ of the normal propagation light exit surface.

  The tilt angle: θ is an angle formed by the conical surface with respect to a plane orthogonal to the conical axis of the normal propagation light exit surface. When the second taper angle: β of the normal propagation light exit surface is used, “90 ° −β Is. Therefore, the inclination angle: 10 degrees on the horizontal axis in FIG. 7A corresponds to the second taper angle: β = 80 degrees, and the inclination angle: 50 degrees corresponds to the taper angle: 40 degrees. Inclination angle: θ corresponds to “incident angle of normal propagation light incident on the normal propagation light exit surface”.

  As shown in FIG. 7, when the tilt angle: θ is 40 degrees (taper angle: β = 50 degrees), the distance: D is about 200 nm, and the tilt angle: θ is 10 degrees (taper angle: β = 80 degrees). Sometimes distance: D is about 1.7 μm.

  That is, if the second taper angle in claim 1 is within the range of “50 degrees <β <90 degrees”, the distance D is several hundred nm to several μm. In the range of “60 degrees ≦ β ≦ 80 degrees”, a working distance of several hundred nm to several μm can be secured even in consideration of the height of the near-field light extruding surface portion. “Non-contact between the probe tip and the surface to be inspected” is ensured, low-resolution scanning can be performed at high speed, and highly efficient inspection is possible.

FIG. 7 (b) shows the ratio of the conical diameter of the near-field light bleed surface: B and the diameter of the conical shape of the normal propagation light exit surface: A: the distance D is changed according to the change of B / A. It shows how it changes. In this example, the taper angle of the normal propagation light exit surface: β = 65 degrees, the taper angle of the near-field light exudation surface: 40 degrees, the refractive index of the core portion with respect to the normal propagation light: 1.53, and the exit side is air. .
From FIG. 7B, it can be seen that if the diameter ratio: B / A is about 0.3 or less, the working distance of several hundred nm to several μm can be secured.

  Returning to FIG. 5, when the normal propagation light propagating through the core portion of the single-mode optical fiber is incident on the near-field light bleed surface 110, it is reflected by the near-field light bleed surface 110, and part of the light is evanescent light as near-field light. It exudes from the light exudation surface 110 to the side of the conductive thin film covering this surface. The evanescent light that exudes excites surface plasmons on the conductive thin film, couples with the excited surface plasmons, propagates along the near-field light exudation surface 110 toward the tip of the near-field light exudation surface, and the tip portion Then, a stable near-field light spot SPE “coupled with surface plasmon” is formed.

Incidentally, the near-field light spot SPE in FIG. 5 is illustratively shown. Since the near-field light spot is not “propagating light”, even if it is generated, it is not observed alone.
The “conductive thin film” formed on the near-field light extruding surface 110 is desirably an Au thin film because the effect of enhancing near-field light by surface plasmons can be obtained and the chemical stability is excellent.

The intensity of the near-field light spot SPE, generally have wavelength dependence as shown in FIG. 8 (a), the wavelength of the Figure: the range of Ramuda21～ramuda22 (Maximum: 1/2 of the _{P 0: P 1} or more The near-field light spot with good intensity can be formed by selecting the (wavelength region). When the conductive thin film for leaching near-field light is the “Au thin film”, a near-field light spot with good intensity can be formed by selecting light having a wavelength falling within a wavelength band of about 480 nm to 700 nm.

The light intensity of the near-field light spot SPE also has “first taper angle: dependence on α”.
FIG. 8B shows a general tendency of exuded near-field light intensity with respect to a conical inclination angle: θ (= 90 degrees−α) forming the near-field light extruding surface, and the inclination angle: θ represents “θa to θb. By selecting an angle of “range (maximum value of light intensity: 1/2 value of P0: range of P1 or more)”, the light intensity of the near-field light spot SPE can be improved. For example, when the conductive film for leaching near-field light is the “Au thin film”, when the incident light wavelength is 532 nm, the tilt angle: θ is about 30 to 50 degrees (taper angle: α = 40 to 50 degrees) ) Is preferred.

  6, the optical fiber probe 100A shown in FIG. 6A is the type shown in FIG. 1, the optical fiber probe 100B shown in FIG. 6B is the type shown in FIG. 3, and the optical fiber probe 100C shown in FIG. It is.

  Angles ξ1, ξ2, and ξ3 in FIG. 6 are “aspect ratios of the probe portion” of the optical fiber probe. As is apparent from FIG. 6, the aspect ratios ξ1, ξ2, and ξ3 are ξ1 <ξ2 <ξ3, and the surface to be measured is scanned with a near-field light spot during high-resolution inspection. In this case, the tolerance for the inclination angle of the profile of the test surface on the scanning line increases in the order of the optical fiber probes 100A, 100B, and 100C. That is, an inclined surface having the taper angle: γ1 or γ2 is formed on the outer peripheral side of the near-field light bleed surface, so that the near-field light spot is also applied to the test surface having a larger inclination angle profile. Inspection becomes possible and the range of inspection objects widens.

Next, manufacturing methods of the various optical fiber probes described above will be described.
FIG. 9 is a diagram for explaining a method of manufacturing an optical fiber probe of the type described with reference to FIG. FIG. 9A shows a single mode optical fiber as a base material.

  The single mode optical fiber FB has a structure having a first core C1, a second core C2, and a cladding part CL around an axis. The single-mode optical fiber FB is selectively (chemically) etched by immersing the lower “flat end” in FIG. 9A in an etching solution.

  When the dissolution rate with respect to the etching solution is R1 in the first core C1, R2 in the second core C2, and R3 in the cladding part CL, the magnitude relationship is “R1 <R2 <R3”.

  FIG. 9B shows a case where the single-mode optical fiber FB shown in FIG. 9A is subjected to selective (chemical) etching with an etchant, and the end face of the first core C1 has “first taper angle: α Is a state in which a conical near-field light bleed surface having a “conical normal propagation light exit surface having a second taper angle: β” is formed on the end surface of the second core.

FIG. 9C is an enlarged view of the left half of FIG.
Let T be the time from the start of selective (chemical) etching until the end face shape as shown in FIG. When the aforementioned dissolution rates: R1, R2, R3 and the first and second taper angles: α, β are used, the following relationship is established between these amounts.

That is, the length of each arrow in FIG. 9C is set to L1, L2, and L3 as shown in the figure. In selective (chemical) etching, the invasion proceeds in a direction perpendicular to the etching surface. Therefore,
L3 = T ・ R3
L2 = L3 · sin β = T · R3 · sin β = T · R2
L1 = L3 · sin α = T · R3 · sin α = T · R1
From these relationships,
The taper angle (first taper angle: α) of the near-field light exudation surface is
sin α = R1 / R3, therefore
α = sin ⁻¹ (R1 / R3)
The taper angle of the normal propagation light exit surface: β is given by
sin β = R2 / R3, therefore
β = sin ⁻¹ (R2 / R3)
Given in.

  That is, when the dissolution rate R1 of the first core C1, the dissolution rate R2 of the second core R2, and the dissolution rate R3 of the clad CL are determined, the first taper angle of the near-field light bleed surface: α, normal propagation light emission The second taper angle of the surface: β is determined.

  If the diameter of the first core C1 is r1 and the diameter of the second core C2 is r2, the cone-shaped diameter of the near-field light extruding surface described with reference to FIG. The ratio of the conical diameter of the light exit surface: A to B / A is determined as r1 / r2.

For example, referring to FIG. 7, if the second taper angle of the normal propagation light exit surface is β = 65 degrees and B / A = 0.2, a working distance of about 900 nm can be realized. If a fiber probe is manufactured, the dissolution rate: R1, R2, R3 and the diameters of the first and second cores: r1, r2,
r1 / r2 = 0.2
65 degrees = sin ⁻¹ R2 / R3,
That is, R2 / R3 = 0.423
In order to satisfy the above, a single mode optical fiber as a base material may be designed or selected.

Adjustment of the dissolution rates of the first core, the second core, and the clad portion can be realized by adjusting the type and amount of additive added to these portions.
As an example, the “dispersion shifted fiber” marketed under the trade name “DS1” by a single-mode optical fiber manufactured by Sumitomo Electric is the first mode when referred to the single-mode optical fiber FB described above. The core C1 is made of a material having a core diameter of 4 μm and “adding 8 mol% of GeO ₂ to pure quartz glass”, and the second core C2 is a core diameter of 14 μm and “adding 2 mol% of GeO ₂ to pure quartz glass”. The clad portion CL is made of pure quartz glass, and the outer peripheral portion has a diameter of 125 μm.

In order to specify “ammonium fluoride aqueous solution and hydrofluoric acid and water etching solution” for selectively (chemically) etching the dispersion-shifted fiber, a 40% by weight ammonium fluoride aqueous solution, 50% hydrofluoric acid and water The mixing ratio (volume ratio) was changed to 40% by weight ammonium fluoride aqueous solution: 50% hydrofluoric acid: water = X: 1: 1 using parameter: X.
And

  Parameter: When the dispersion-shifted fiber is immersed in an etching solution specified by X for 8 hours to perform selectivity (chemical etching), a conical first taper angle formed on the first core: α, The conical second taper angle: β formed in the second core changes as shown in FIG. 10A according to the change of the parameter: X.

In FIG. 10A, a curve 10-1 indicates a change in the first taper angle: α, and a curve 10-2 indicates a change in the second taper angle: β.
Forming “the first taper angle of the near-field light bleed surface: α is approximately 43 degrees and the second taper angle of the normal propagation light exit surface: β is approximately 60 degrees” using the commercially available dispersion-shifted fiber as a base material. When trying to do so, from FIG. 10A, it suffices to immerse in an etching solution having a parameter: X = 4 for 8 hours. At this time, the outer periphery of the cladding part is also etched, and the diameter of the cladding part at the part functioning as the probe part becomes 30 to 40 μm.

FIG. 10B shows how the dissolution rate (nm / h) of pure quartz glass and “quartz glass doped with GeO ₂ ” in the etching solution changes with respect to the parameter X of the etching solution. FIG. The broken straight line 10-3 relates to “pure quartz glass”, and the curve 10-4 relates to “pure quartz glass added with 25 mol% of GeO ₂ ”. As can be seen from this figure, even when “addition amount of GeO ₂ is the same”, the dissolution rate tends to decrease as the parameter X increases, and the dissolution increases as the addition amount of GeO ₂ increases (addition concentration increases). There is a tendency for speed to decrease.

Therefore, the dissolution rates of the first core, the second core, and the cladding can be adjusted by the addition amount of GeO ₂ and the parameter X of the etchant.

  “Electrically conductive thin film for near-field light leaching” is applied to at least the near-field light bleed surface of the single-mode optical fiber formed with the near-field light bleed surface and the normal propagation light exit surface as described above. If formed by an appropriate film formation process, an optical fiber probe of the type described in the embodiment in FIG. 1 can be realized.

  To supplement a little explanation, the first core and the second core are quartz glass to which germanium dioxide is added, and the cladding portion is undoped quartz glass. These are “isotropic glasses”, and dissolution by the etching solution is not performed. Although it is isotropically performed, the dissolution rate varies depending on the presence or absence of addition of germanium dioxide as an impurity and the difference in the amount added, so the dissolution rate is discontinuous at the boundary between the first core, the second core, and the cladding. In order to change, a slope is formed on the side with a lower dissolution rate.

  That is, in the manufacturing method described above, germanium dioxide is added to the first core and the second core of the core portion so that the addition amount of the first core is relatively higher than the addition amount of the second core. Etching is performed by immersing the end surface of the single-mode optical fiber in the etching solution so that the dissolution rate of the aqueous solution of ammonium fluoride and the etching solution composed of hydrofluoric acid and water decreases in the order of the cladding, the second core, and the first core. Etching step for forming a near-field light extruding surface having a first taper angle: α on the first core and a normal propagation light emitting surface having a second taper angle: β on the second core, and at least near-field light A conductive thin film forming step of forming a conductive thin film for leaching near-field light on the exuding surface (claim 13).

  In the optical fiber probe manufactured in this way, the core part and the clad part are made of quartz glass as a base material (Claim 5), and the core part is made of silica glass to which germanium dioxide is added, and germanium dioxide is added. The amount is selected such that the additive amount in the first core is relatively large relative to the additive amount in the second core, and each additive amount provides the desired dissolution rate for the etchant in the first core and the second core. (Claim 6) The clad portion is pure quartz glass (Claim 7).

In the case of using the above-mentioned commercially available “dispersion shifted fiber” as the single mode optical fiber as the base material, the second taper angle of the formed normal propagation light exit surface: β is “± 7 degrees with respect to the design value” Degree of variation ". This is due to “variation in the amount of GeO ₂ added” to the second core.

  The inventors made a prototype of a single mode optical fiber as a base material by the following method.

That is, GeO ₂ -added quartz glass (addition amount: 2 mol%) serving as the second core was deposited on the inner wall of the pure quartz glass tube serving as the cladding by the MCVD method, and the inner space was manufactured by VAD. “Quartz glass rod added with GeO ₂ to be the first core C1 (added amount: 8 mol%)” was inserted and solidified, and by drawing, the first core C1 having a diameter of 0.8 μm and a diameter of 4 μm A single-mode optical fiber made of a second core C2 and a clad portion CL having a diameter of 125 μm was made as an experiment. In this prototype optical fiber, variation of the normal propagation light exit surface with respect to the taper angle: β could be effectively reduced, and the yield of optical fiber probe manufacturing could be improved.

Next, a method for manufacturing an optical fiber probe of the type shown in FIG. 3 will be specifically described.
A single-mode optical fiber FB that is a base material shown in FIG. 11A is a prototype manufactured by the same process as the prototype optical fiber described above, and has a first core C1 having a diameter of 0.8 μm and a diameter of 4 μm. The second core C2 and a clad portion CL having a diameter of 125 μm.

The flat end face (the lower face in the figure) of the single-odd optical fiber FB is set to “parameter: X adjusted to 1.7 and left for about 10 days, and the ammonium fluoride concentration slightly increased due to natural deterioration. The first etching step is carried out using as a first etching solution the one (dissolution rate of GeO ₂ -added quartz glass is slightly higher than that of pure quartz glass).

  FIG. 11B shows a state after the first etching process has been performed for 110 minutes. After the first etching process, the diameter of the clad CL became about 20 μm from 125 μm before the process. The cone-shaped apex angle formed in the first core C1 (twice the taper angle): α1 is approximately 143 degrees, and the cone-shaped taper angle formed in the second core C2: β1 is approximately 75 degrees, with α1 The difference with β1 is only a few degrees.

  After the first etching step, the second etching step is performed for about 2 minutes with the second etching liquid adjusted to the parameter X = 10. FIG. 11C shows a state after the second etching step. In this state, a conical near-field light bleed surface having a first taper angle: α = 44.5 degrees is formed on the first core C1, and a second taper angle: β = 72. A normal propagation light exit surface having 5 degrees and an inclined surface having a taper angle: γ1 (> β) on its outer peripheral portion were formed in a conical shape. An optical fiber probe can be obtained by forming a conductive thin film on at least the near-field light exudation surface of the end portion of the optical fiber on which the near-field light exudation surface and the normal propagation light exit surface are formed.

  That is, in the manufacturing method described immediately above, germanium dioxide is added to the first core C1 and the second core C2 of the core portion, and “the addition amount of the first core C1 is relatively relative to the addition amount of the second core C2. The end surface of the single-mode optical fiber FB, which is added so as to be “high”, and the dissolution rate with respect to the etching solution composed of an aqueous ammonium fluoride solution and hydrofluoric acid and water decreases in the order of the cladding portion CL, the second core C2, and the first core C1. Is immersed in a first etching solution having a relatively low mixing ratio of an ammonium fluoride aqueous solution (a solution adjusted to X = 1 and allowed to naturally deteriorate) to form an inclined surface in the core portion. The end surface of the single mode optical fiber FB having the inclined surface formed in the core portion by the etching process and the first etching process is formed on the second edge where the mixing ratio of the aqueous ammonium fluoride solution is relatively high. A near-field light extruding surface having a first taper angle: α and a normal propagation light emitting surface having a second taper angle: β; A second etching step of forming an inclined surface having an inclination angle: γ1 on the outer peripheral portion of the normal propagation light exit surface of the second core C2, and a conductive thin film for leaching near-field light at least on the near-field light bleed surface And a conductive thin film forming step for forming (Claim 14).

  The optical fiber probe manufactured in this way has an inclined surface having a taper angle: γ1 (<β) on the outer peripheral side of the normal propagation light exit surface (Claims 2 and 3), and the core portion C1. , C2 and the clad portion CL are made of quartz glass as a base material (Claim 5), and the core portions C1 and C2 are quartz glass to which germanium dioxide is added, and the amount of germanium dioxide added is the first core. The additive amount in C1 is relatively large relative to the additive amount in the second core C2, and each additive amount is selected to provide a desired dissolution rate of the first core C1 and the second core C2 in the etchant (claimed). Item 6) The clad CL is pure quartz glass (Claim 7).

Next, a method for manufacturing an optical fiber probe of the type shown in FIG. 4 will be specifically described with reference to FIG.
In FIG. 12A, the single mode optical fiber FB1 serving as the base material has a first core C1 having a diameter of 0.8 μm, a second core C2 having a diameter of 4 μm, and a cladding portion having a diameter of 125 μm, as described above. It becomes more. The clad part is composed of an inner clad part CL1 and an outer clad part CL2. The inner cladding portion CL1 has a diameter of 32 μm, and the outer cladding portion CL2 has a diameter of 125 μm. The first core C1 is manufactured by VAD, and the second core CL2 is formed by deposition by MCVD.

  The inner clad part CL1 and the outer clad part CL2 are different in the presence or absence of anhydrous chlorine treatment. That is, the inner cladding part CL1 is “pure quartz glass not subjected to anhydrous chlorine treatment”, and the outer cladding part CL2 is “quartz glass subjected to anhydrous chlorine treatment”.

  In “quartz glass that has been subjected to anhydrous chlorine treatment”, OH has been drastically reduced by the anhydrous chlorine treatment, and trace amounts of chlorine have been added. By reducing OH and adding chlorine, an “ammonium fluoride aqueous solution” In addition, the dissolution rate with respect to an etching solution composed of hydrofluoric acid and water is slightly higher than that of pure quartz glass.

  Therefore, the first etching process is performed with the first etching solution having the parameter: X = 1.7. The result of performing the first etching process for 60 minutes is shown in FIG. A conical portion having a taper angle: α1 is formed in the first core C1 portion, a conical portion having a taper angle: β1 is formed in the second core C2, and a taper angle is formed on the outer inner cladding portion CL1. : A conical portion of γ0 was formed.

  Subsequently, when the second etching step was performed for 2 minutes with the second etching solution adjusted to X = 3, as shown in FIG. 12C, the first core C1 has a conical shape having a first taper angle: α. A near-field light extruding surface is formed, a normal propagation light emitting surface having a second taper angle: β is formed on the second core C2, and a conical inclined surface having a taper angle: γ1 is formed on the outer side, and the inner cladding is formed. A conical inclined surface having a taper angle of γ2 was formed in the portion CL1.

  The first taper angle: α = 44.5 degrees and the second taper angle: β = 72.5 degrees. The taper angle: γ0 is an angle close to 90 degrees, and the taper angle: γ2 is about 65 degrees. An optical fiber probe can be obtained by forming a conductive thin film on “at least the near-field light bleed surface” of the end face thus etched.

Incidentally, in the optical fiber etching described above, the first taper angle: α and the second taper angle: β when the etching solution having the same composition (that is, the same value of X) is used for the first etching and the second etching. Is as follows.
X α β
1.7 65 72.5
2 55.5 71.5
3 41 64
4 33 58
10 25 50.

  The dissolution rate of the outer cladding portion CL2 with respect to the first and second etching solutions depends on the amount of chlorine added to the outer cladding portion CL2 and the decreased OH amount by the anhydrous chlorine treatment, but the chlorine addition amount and the OH reduction amount. Since it is difficult to accurately control the taper angles after the first and second etching steps, the reproducibility of the taper angles γ0 and γ2 varies for each base optical fiber.

  The taper angle γ2 is not a large angle, but the diameter of the first core C1 is 0.8 μm and the diameter of the second core C2 is 4 μm, whereas the inner cladding portion CL1 has a large diameter of 32 μm. The height difference between the inner circumference and the outer circumference of the inner cladding portion CL1 due to the formed taper is large, and the effect of increasing the aspect ratio of the probe portion of the optical fiber probe is great.

  In consideration of variations in the reproducibility of the taper angle γ2 due to the difficulty in accurately controlling the amount of chlorine added, the diameter of the inner cladding CL1 is preferably about 20 μm rather than the above 32 μm.

  That is, the manufacturing method described with reference to FIG. 12 is the optical fiber probe manufacturing method according to claim 14 described above, wherein the clad portion of the single-mode optical fiber FB1 is separated from the inner clad portion CL1 made of pure quartz glass with anhydrous water. The outer clad portion CL2 made of chlorinated silica glass is used, and an inclined surface having a taper angle of γ2 is formed in the inner clad portion by the first and second etching steps (claim 15).

  The optical fiber probe manufactured in this way has an inclined surface having a taper angle: γ1 (<β) on the outer peripheral side of the normal propagation light exit surface (Claims 2 and 3), and the taper angle: An inclined surface having γ2 is formed in the cladding part (Claim 4), and the core parts C1 and C2 and the cladding parts CL1 and CL2 are made of quartz glass (Claim 5).

  The core portions C1 and C2 are quartz glass to which germanium dioxide is added, and the addition amount of germanium dioxide is relatively large with respect to the addition amount in the first core C1 and the addition amount in the second core C2. Each addition amount is selected so as to give a desired dissolution rate with respect to the etching solution of the first core C1 and the second core C2 (Claim 6), and on the outer peripheral portion of the normal propagation light exit surface in the second core C2. An inclined surface having a taper angle of γ1 is formed (Claim 8), the clad portion includes quartz glass that has been subjected to anhydrous chlorine treatment (Claim 9), and is formed on the outer peripheral portion of the normal propagation light exit surface in the second core C2. An inclined surface having a taper angle of γ1 is formed (Claim 10), the clad portion is composed of an inner clad portion CL1 and an outer clad portion CL2, and the inner clad portion CL1 is pure quartz glass, and the outer clad portion C. L2 is quartz glass that has been subjected to anhydrous chlorine treatment, and an inclined surface having a taper angle of γ2 is formed in the inner cladding portion (claim 11).

  In the manufacturing method described above with reference to FIGS. 9, 11 and 12, the etching solution, the first etching solution, and the second etching solution are “concentration: 40 wt% ammonium fluoride aqueous solution and concentration: 50 wt% fluorine. It consists of an acid and water "(claim 16).

In the optical fiber probe using the quartz glass described above as a base material, since the addition amount of GeO ₂ is different between the first core and the second core, the refractive index is different between the first core and the second core. The difference in refractive index is a slight difference (about 0.1 to 0.2%) and does not substantially affect the optical characteristics of the core portion. Further, the relative refractive index difference between the second core and the clad portion (or the inner clad portion) is 0.2% or less.

  To supplement the description, a “single mode optical fiber” is used as a substrate in the optical fiber probe of the present invention. The “condition under which the waveguide mode in an optical fiber is a single mode for light of a certain wavelength or less” is determined by the size of the core portion and the “difference in refractive index between the core portion and the cladding”. In the optical fiber probe of the present invention, since the core portion is composed of the first core and the second core, the condition for the single mode is that the size of the second core and “the relative refractive index difference between the second core and the cladding portion”. ”

In general, the upper limit of the wavelength at which an optical fiber can propagate light in a single mode is called a “cutoff wavelength”. The cutoff wavelength: λc is the normalized frequency: ν, the refractive index of the core part: n ₁ , The refractive index of the cladding part: n ₂ , the radius of the core part: a, the relative refractive index difference between the core part and the cladding part: Δ (= n ₁ −n ₂ ) / n ₁ )
λc = (2π / ν) a · n ₁ √ (2 · Δ)
Given in.

  From this, the cut-off frequency: λc shifts to the longer wavelength side as the core diameter: 2 · a increases and as the relative refractive index difference: Δ increases.

  In the above specific example of the optical fiber probe, in order to set the single-mode cutoff wavelength to the visible region or shorter, the diameter of the core portion is 4 μm, and the relative refractive index difference between the core portion and the cladding portion is 0.2 μm. % Or less.

  Under such conditions, when the diameter of the first core is 0.8 μm and the diameter of the second core is 4 μm, the aspect ratio when the optical fiber probe of the type shown in FIG. 4 and particularly the type of FIG. 4, the aspect ratio is effectively large, and as described above with reference to FIG. 6, it is also close to the test surface having a profile with a large inclination angle. Inspection with a field light spot becomes possible, and the width of the inspection object widens.

  Hereinafter, embodiments relating to an inspection apparatus and an inspection method will be described.

FIG. 13 shows an embodiment of the inspection apparatus.
This inspection apparatus can be implemented as, for example, “a near-field optical microscope for measuring optical physical properties in a minute region of a sample as a subject”.

  The inspection apparatus includes a light source 11 that emits laser light, a drive power source 11a that drives the light source 11, a light wavelength switching unit 11b that switches the wavelength of the laser light emitted from the light source 11, and an optical path of the laser light emitted from the light source 11. A beam splitter 12 disposed therein, a half-wave plate 18a and a quarter-wave plate 18b disposed in the optical path of the laser light transmitted through the beam splitter 12, and an adjusting unit 18 for adjusting these wave plates; The optical fiber probe 13 that irradiates the test surface 2a of the subject 2 with the light transmitted through the wave plates 18a and 18b, the photodetector 14 that detects the return light from the test surface 2a, the probe control unit 15, and the image The processing unit 16, the image display unit 17, and the control unit 40 are included. The control means 40 is constituted by a microcomputer or the like and controls the entire apparatus.

  The optical fiber probe 13 has a probe portion 22 formed at the tip of a propagation portion 21 of a single-mode optical fiber, and the types described with reference to FIGS. 1, 3, and 4 can be used. For example, if the type shown in FIG. 4 is used as the optical fiber probe 13, the near-field is also closer to the “test surface having a larger profile angle” than those of the type shown in FIGS. 1 and 3. Inspection with a light spot becomes possible, and the range of inspection objects widens.

  In the following, it is assumed that the optical fiber probe 13 is of the type shown in FIG. In other words, a near-field light extruding surface 20a and a normal propagation light emitting surface 20b are formed on the end face of the optical fiber in the probe portion 22.

  Further, the conductive thin film formed on the end face of the optical fiber is of the type shown in FIG. 2C, and the “near-field light leaching thin film by Au” is formed on the near-field light bleed surface 20a. A polarizing film is formed on the propagation light exit surface 20b. This “polarizing film” is obtained by forming a “sub-wavelength structure wire grid having a polarizing function” on an Au thin film.

  The sub-wavelength structure wire grid is a well-known “cross-sectional shape is rectangular, width: w, thickness: t, wire is formed as a grid with pitch: p”, and pitch: p is laser light. Smaller than the wavelength. As is well known, by adjusting the w, p, and t, a polarization function (a function of transmitting only specific polarization component light) can be imparted to the light source wavelength. Such a wire grid can be formed by “a fine process such as film formation on the normal propagation light exit surface and ion beam etching”. The space between the wires of the wire grid may be filled with a “dielectric other than air” in consideration of improving the mechanical strength of the microstructure.

The light source 11 is driven by a driving power source 11a and emits laser light having a wavelength set by the optical wavelength switching unit 11b. Part of the emitted laser light passes through the beam splitter 12, and then passes through the half-wave plate 18a and the quarter-wave plate 18b.
The half-wave plate 18a and the quarter-wave plate 18b can be rotated and adjusted around the optical axis of the transmitted light, and their states are adjusted by the adjusting means 18 to control the polarization of the laser light. That is, the half-wave plate 18 a and the quarter-wave plate 18 b together with the adjusting unit 18 constitute a “polarization adjusting unit”.

  The laser light transmitted through the half-wave plate 18a and the quarter-wave plate 18b is incident on the core portion of the optical fiber probe 13 and propagates in the core portion of the propagation portion 21 as a single mode wave. Since the light propagation part 21 of the optical fiber probe 13 is long and the light propagation part 21 is bent, “the polarization state of the propagating laser light is disturbed by the bending of the light propagation part 21 (linearly polarized light becomes elliptical)”. By adjusting the state of the / 4 wavelength plate 18b, “this disturbance of the polarization state is corrected”, and the laser light incident on the probe unit 22 is linearly polarized.

  As described above, the ¼ wavelength plate 18b “corrects the polarization state disturbance of the propagating laser beam due to the bending of the light propagation portion 21”, so that the optical fiber probe is configured so that the polarization state is not disturbed. Is unnecessary and can be omitted.

  When the normal propagation light propagating through the core part reaches the probe unit 22, a part of the normal propagation light enters the near-field light extruding surface 20a, and the other part enters the normal propagation light exit surface 20b. Most of the normal propagation light incident on the near-field light exuding surface 20a is totally reflected by the near-field light exuding surface, and the evanescent light (near-field light) that exudes at this time excites surface plasmons on the conductive thin film. It couples with this and propagates through the conductive thin film to form a “near-field light spot (see FIG. 5)” at the tip of the near-field light exudation surface 20a. The near-field light spot is formed at a position of several nm to several tens of nm from the tip of the near-field light exudation surface.

  On the other hand, the normal propagating light incident on the normal propagating light exit surface 20b exits from the normal propagating light exit surface 20b, and is more “distant on the optical fiber axis than the near-field light spot (the tip of the near-field light extruding portion). The normal propagation light spot is formed at a position separated by several hundred nm to several μm from the head).

  As described above, the normal propagation light incident on the normal propagation light exit surface 20b is linearly polarized by the half-wave plate 18a and the quarter-wave plate 18b, and the normal propagation exits from the normal propagation light exit surface 20b. Light is subjected to the action of the wire grid which is the polarizing film. That is, if the direction of the polarization plane of the normal propagation light in the core matches the “direction that the wire grid should transmit (wire arrangement direction)”, substantially 100% of the normal propagation light is transmitted through the wire grid. Therefore, the intensity of the normal propagation light spot SP can be maximized.

  When performing a low-resolution inspection of the subject 2 with the normal propagation light spot, the surface 2a is scanned in this state. The near-field light spot stays at the tip of the near-field light extruding surface and does not reach the test surface 2a, so that “scanning with a normal propagation light spot” is not affected. In addition, since a sufficient working distance is guaranteed, low resolution scanning can be performed at high speed.

  On the other hand, when the inspection with the near-field light spot is performed, the test surface 2a is brought very close to the tip of the near-field light extruding surface 20a, and the test surface is scanned with the near-field light spot. If normal propagation light is emitted from the exit surface 20a, the emitted normal propagation light may irradiate the surface 2a to be tested, and may "act as noise with respect to scanning by the near-field light spot".

  Therefore, in this case, by adjusting the rotation of the half-wave plate 18a and the quarter-wave plate 18b around the transmission optical axis by the adjusting means 18, the polarization plane of the normal propagation light incident on the probe unit 22 is changed to “wire”. By making “perpendicular to the arrangement direction of the grid”, the intensity of the normal propagation light emitted from the normal propagation light exit surface 20b can be substantially zero, and the noise effect of the normal propagation light can be completely prevented.

  The optical fiber probe 13 is attached to the probe controller 15 in the vicinity of the light emitting part. The probe control unit 15 is a known one configured by, for example, a “three-axis actuator” or the like. ”And a function of displacing in two directions orthogonal thereto. Although not described in detail, in the scan of the test surface by the near-field light spot, the tip of the probe portion is close to the test surface with an order of “several nm to several tens of nm”, and “a known shear force is used with a shear force microscope. By “tracking control”, scanning is performed following the surface shape of the test surface 2a.

  When switching from a low-resolution inspection using a normal propagation light spot to a high-resolution inspection using a near-field light spot, the probe control unit 15 is controlled by the control means 40 to identify the probe tip of the optical fiber probe 13 by “low-resolution scanning”. The area where the high-resolution scanning is to be performed "is accessed. It goes without saying that "the polarization of the laser beam is controlled by operating the polarization control means" in accordance with this switching. The “amount of change in the distance between the probe tip of the optical fiber probe 13 and the test surface 2a” associated with the switching is experimentally determined in advance, converted into data, and stored in the control means 40.

  The scanning of the test surface may be performed by fixing the probe portion of the optical fiber probe 13 and displacing the subject 2. Alternatively, the scanning of the test surface may be performed between the probe portion of the optical fiber probe 13 and the test surface 2. The distance may be switched by “displacement of the subject (vertical displacement in FIG. 1)”, and scanning by the near-field light spot or the normal propagation light spot may be performed by the displacement of the optical fiber probe. That is, scanning can be executed by three-dimensional relative displacement between the test surface and the optical fiber probe.

  As shown in FIG. 13, the light reflected by the test surface 2a returns as “return light” through the optical fiber probe 13, passes through the quarter-wave plate 18b and the half-wave plate 18a, and passes through the beam splitter 12. And is received by the photodetector 14. The photodetector 14 photoelectrically converts the received return light to generate a luminance signal. A scanned image is created by the image processing unit 16 based on the generated luminance signal and displayed on the image display unit 17. The inspector can inspect by measuring and observing details of the surface 2a to be inspected based on the image displayed on the image display unit.

  Specifically, first, the distance between the tip of the probe portion 22 of the optical fiber probe 13 and the test surface 2a is set to “a distance suitable for scanning with a normal propagation light spot (several hundred nm to several μm)” for normal propagation. Perform low resolution scanning with a light spot. At this time, the polarization of the polarization plane of the laser light from the light source 11 side is controlled to be “a direction in which the wire grid forming the polarizing film is substantially 100% transmitted”. During the low-resolution scanning, the tip of the optical fiber probe 13 is displaced by the probe control unit 15 in the vertical direction in FIG. 13 so that the luminance signal is maximized. Is known to have a rough surface.

  Based on the “optical property information of the surface 2a to be examined” obtained from the image displayed on the image display unit 17, a minute region for which a more detailed optical property inspection is desired is specified, and the optical fiber probe 13 is horizontally directed to the region. “Position alignment” is performed by moving, and “high-resolution inspection by high-resolution scanning with a near-field light spot” is performed only on the region concerned.

  That is, after the “positioning”, the probe control unit 15 moves the probe unit 22 in the direction approaching the test surface 2a in a state where the near-field light spot is formed. When the distance between the tip of the near-field light extruding surface 20a and the test surface 2a is ¼ or less of the wavelength of the laser light emitted from the light source 11, the near-field light from the near-field light spot is detected by the test surface 2a. Is irradiated. As described above, the “displacement amount of the tip of the probe portion of the optical fiber probe 13 toward the test surface 2a” at this time is experimentally determined in advance and converted into data and stored in the control means 40.

  The near-field light irradiated on the test surface 2a is reflected by the test surface 2a to become propagating light, which is guided to the photodetector 14 through the core 31 as test light. For high-resolution scanning. At this time, the polarization of the polarization plane of the laser light from the light source 11 side is controlled in the “direction substantially blocked by the wire grid 100%”. The probe control unit 15 scans the probe unit 22 at low speed following the undulations and unevenness of the surface to be measured.

  Since rough undulations and irregularities on the surface to be measured are known by low-resolution inspection, by using this rough undulation and irregularity information, in areas with no irregularities and undulations during high-resolution inspections, Scanning for resolution inspection can be performed at high speed, and the efficiency of high-resolution inspection can be effectively increased.

  As described above, by moving the probe portion 22 at the tip of the optical fiber probe 13 in the direction of approaching and separating from the test surface 2a, high-resolution inspection using near-field light and low-resolution inspection using normal propagation light spots are performed. It can be done selectively. Measurement with high S / N becomes possible by suppressing the emission of normal propagation light during high resolution inspection.

  When switching from the low resolution scanning to the high resolution scanning, the height of the tip of the probe unit 22 with respect to the test surface 2a is constant in order to “align” the probe unit 22 to the high resolution scanning region. Therefore, it is not necessary to control the displacement in the proximity / separation direction during the alignment, and the large working distance and phase corresponding to the distance (about several hundred nm to several um) between the normal propagation light spot and the tip of the probe described above. As a result, faster access (positioning) is possible, leading to a significant reduction in measurement time.

  FIG. 14 shows another embodiment of the inspection apparatus. In order to avoid complications, the same reference numerals as those in FIG. 13 are given to those which are not likely to be confused, and the description related to FIG.

  In the embodiment shown in FIG. 13, the detection means is configured to “detect the scattered light or reflected light from the surface 2a to be detected as return light via the optical fiber probe 13”. In this embodiment, inspection is performed by detecting the inspection light passing through the test surface 2a1 by the detection means 14, 16, and 17 without using the optical fiber probe. That is, in the embodiment shown in FIG. 3, the subject 2A is transparent to the inspection laser light, and the inspection light passing through the subject surface 2a1 passes through the subject 2A and is received by the photodetector 14. The

  A luminance signal is generated by the photodetector 14, and a scanned image is created by the image processing unit 16 based on the generated luminance signal and displayed on the image display unit 17. The inspection process is the same as that of the inspection apparatus of FIG.

In order to realize both “a high intensity light spot in inspection using near-field light” and “high polarization controllability in inspection using normal propagation light”, it is preferable to select a wavelength suitable for each inspection.
As an example, when a “Au thin film” is formed as a conductive thin film on the near-field light bleed surface and a “wire grid with Au” is formed as a polarizing film on the normal propagation light exit surface, an inspection by a near-field light spot is performed. For example, “a laser beam having a wavelength of 532 nm” is emitted from the light source 11 in a wavelength region: 500 to 550 nm where the intensity of the near-field light spot is increased by the effect of enhancing the near-field light by the surface plasmon. In the case of inspecting with a light spot, it is preferable to emit a laser beam having a wavelength capable of satisfactorily controlling the polarization with a wire grid, for example, a wavelength of 633 nm from the light source 11.

  The inspection apparatus shown in the embodiment in FIGS. 13 and 14 has a “light wavelength switching unit 11b for switching the wavelength of the laser light emitted from the light source 11” in order to implement this, and performs a low-resolution inspection. When the high-resolution inspection is performed, the wavelength of the laser light emitted from the light source 11 is switched to a wavelength suitable for each inspection. Specifically, a plurality of laser light sources having different emission wavelengths are prepared as the light source 11, and the light wavelength switching unit 11b selects one of these laser light sources suitable for the inspection resolution to emit light.

  Each inspection apparatus described in the embodiment with reference to FIGS. 13 and 14 is an inspection apparatus that optically scans and inspects the test surfaces 2a and 2a1 of the subjects 2 and 2A, and emits light. A light source 11, a single-mode optical fiber that propagates light from the light source 11, and has a near-field light bleed surface 20 a and a normal-propagation light exit surface 20 b formed at the emission portion, and at least the near-field light bleed surface. Low-resolution inspection using a normal propagation light spot formed by a normal propagation light emitted from the normal propagation light exit surface 20b of the optical fiber probe and a conductive thin film for exuding near-field light. The low-resolution scanning for scanning and the high-resolution scanning for high-resolution inspection using the near-field light spot of the near-field light that oozes from the near-field light bleed surface 20a are selectively performed on the test surfaces 2a and 2a1. Scanning means 15 and detection processing means 14, 16, and 17 for detecting inspection light via the test surfaces 2 a and 2 a 1 and processing the data, and the optical fiber probe 13 is as defined in claim 1. (Claim 17). Of course, the optical fiber probe according to any one of claims 2 to 12 can also be used.

The light source 11 selectively emits light of different wavelengths according to the low resolution inspection and the high resolution inspection.
Therefore, an inspection method for optically scanning the test surfaces 2a and 2a1 of the subjects 2 and 2A by using the above-described inspection apparatus, and inspecting the light emitted from the light source 11 with the optical fiber probe 13 The low-resolution scanning for the low-resolution inspection by the normal propagation light spot formed by the normal propagation light emitted from the normal propagation light exit surface 20b of the optical fiber probe and the proximity exuding from the near-field light extruding surface 20a High-resolution scanning for high-resolution inspection using a near-field light spot of field light is selectively performed on the test surfaces 2a and 2a1 by the scanning unit 15, and the test surface is detected by the detection processing units 14, 16, and 17 An inspection method for detecting data through 2a and 2a1 and processing the data (Claim 19) is implemented, and light of a different wavelength is emitted from the light source 11 according to the low resolution inspection and the high resolution inspection. It is radiated in 択的 (claim 20).

It is a figure for demonstrating one Embodiment of an optical fiber probe. It is a figure for demonstrating the form of the electroconductive thin film provided in an optical fiber probe. It is a figure for demonstrating another form of implementation of an optical fiber probe. It is a figure for demonstrating the other form of implementation of an optical fiber probe. It is a figure for demonstrating a near field light spot and a normal propagation light spot. It is a figure for demonstrating the magnitude of the aspect-ratio of an optical fiber probe. It is a figure for demonstrating the formation position of a normal propagation light spot. It is a figure for demonstrating the dependence with respect to the wavelength and the inclination | tilt angle of exuding near-field light of the intensity | strength of the exuding near-field light which exudes from the near-field light exuding surface. It is a figure for demonstrating one Embodiment of the optical fiber probe manufacturing method. It is a figure for demonstrating the effect | action of the etching by the said manufacturing method. It is a figure for demonstrating another form of implementation of the optical fiber probe manufacturing method. It is a figure for demonstrating the other form of implementation of the optical fiber probe manufacturing method. It is a figure for demonstrating one Embodiment of an inspection apparatus. It is a figure for demonstrating another form of implementation of a test | inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical fiber probe 101 1st core 102 2nd core 103 Clad part 110 Near field light bleed surface 112 Normal propagation light emission surface FV Single mode optical fiber PR Probe part (alpha) 1st taper angle (beta) 2nd taper angle

Claims (20)

An optical fiber probe used for optical inspection that performs low-resolution inspection using a normal propagation light spot and high-resolution inspection using a near-field light spot,
A conical near-field light bleed surface having a first taper angle: α on the core portion of one end face of the single mode optical fiber having a core portion for propagating light and a clad portion surrounding the core portion; The near-field light bleed surface has a conical-shaped normal propagation light exit surface coaxially surrounding the near-field light bleed surface and having a second taper angle: β (> α). A conductive thin film is formed for
The cladding portion has a higher dissolution rate with respect to the etching solution than the core portion, and the core portion has a first core and a second core that have different dissolution rates with respect to the etching solution, and are selective (chemical) etching. Accordingly, a near-field light extruding surface is formed on the first core, and a normal propagation light emitting surface is formed on the second core, and the second taper angle: β (degrees) is
50 <β <90
An optical fiber probe characterized by being in the range. The optical fiber probe according to claim 1,
An optical fiber probe having an inclined surface having a taper angle: γ on an outer peripheral side of a normal propagation light exit surface. The optical fiber probe according to claim 2, wherein
An inclined surface having a taper angle: γ (<90 degrees) is formed on the outer peripheral portion of the normal propagation light exit surface of the second core, and the taper angle: γ is γ1 smaller than the taper angle: β. An optical fiber probe. The optical fiber probe according to claim 2 or 3,
An optical fiber probe characterized in that an inclined surface having a taper angle: γ is formed in the clad portion, and the taper angle: γ is γ2. The optical fiber probe according to any one of claims 1 to 4,
An optical fiber probe, wherein the core part and the clad part are made of quartz glass as a base material. The optical fiber probe according to claim 5, wherein
The core part is quartz glass to which germanium dioxide is added, and the addition amount of germanium dioxide is relatively large with respect to the addition amount in the first core. An optical fiber probe selected to provide a desired dissolution rate for the etching solution of the first core and the second core. The optical fiber probe according to claim 6, wherein
An optical fiber probe characterized in that a clad part is pure silica glass. The optical fiber probe according to claim 7, wherein
An optical fiber probe characterized in that an inclined surface having a taper angle: γ1 is formed on the outer peripheral portion of the normal propagation light exit surface in the second core. The optical fiber probe according to claim 6, wherein
An optical fiber probe, wherein the clad portion includes quartz glass that has been subjected to anhydrous chlorine treatment. The optical fiber probe according to claim 9, wherein
An optical fiber probe characterized in that an inclined surface having a taper angle: γ1 is formed on the outer peripheral portion of the normal propagation light exit surface in the second core. The optical fiber probe according to claim 9 or 10,
The clad portion is composed of an inner clad portion and an outer clad portion, the inner clad portion is pure quartz glass, the outer clad portion is quartz glass that has been subjected to anhydrous chlorine treatment, and the inner clad portion is inclined at a taper angle of γ2. An optical fiber probe having a surface formed thereon. The optical fiber probe according to any one of claims 1 to 11,
Tapered angle of normal propagation light exit surface: β (degree) is 60 ≦ β ≦ 80
An optical fiber probe characterized by being in the range. Germanium dioxide is added to the first core and the second core of the core so that the amount of the first core added is relatively higher than the amount of the second core added, and the aqueous ammonium fluoride solution and hydrofluoric acid Etching is performed by immersing the end surface of the single-mode optical fiber in the etching solution so that the dissolution rate with respect to the etching solution made of water and water decreases in the order of the cladding portion, the second core, and the first core. An etching process for forming a near-field light extruding surface having a taper angle: α and a normal propagation light emitting surface having a second taper angle: β on the second core;
A method for producing an optical fiber probe, comprising: a conductive thin film forming step of forming a conductive thin film for leaching near-field light on at least the near-field light bleed surface. Germanium dioxide is added to the first core and the second core of the core so that the amount of the first core added is relatively higher than the amount of the second core added, and the aqueous ammonium fluoride solution and hydrofluoric acid The first etching solution having a relatively low mixing ratio of the aqueous ammonium fluoride solution is formed on the end surface of the single mode optical fiber whose dissolution rate with respect to the etching solution made of water and water decreases in the order of the cladding portion, the second core, and the first core. A first etching step in which an inclined surface is formed in the core part by dipping in
The end surface of the single mode optical fiber having the inclined surface formed in the core portion by the first etching step is immersed in a second etching solution having a relatively high mixing ratio of the ammonium fluoride aqueous solution, and the first taper angle: α And a normal propagation light exit surface having a second taper angle: β, and an inclined surface having an inclination angle: γ1 on the outer periphery of the normal propagation light exit surface of the second core. A second etching step to be formed;
A method for producing an optical fiber probe, comprising: a conductive thin film forming step of forming a conductive thin film for leaching near-field light on at least the near-field light bleed surface. In the manufacturing method of the optical fiber probe according to claim 14,
The clad part of the single-mode optical fiber is constituted by an inner clad part made of pure silica glass not subjected to anhydrous chlorine treatment and an outer clad part made of quartz glass treated with anhydrous chlorine,
A method of manufacturing an optical fiber probe, wherein an inclined surface having a taper angle of γ2 is formed in an inner cladding portion by first and second etching steps. In the manufacturing method of the optical fiber probe according to any one of claims 13 to 15,
A method of manufacturing an optical fiber probe, wherein the etching solution, the first etching solution, and the second etching solution comprise an ammonium fluoride aqueous solution having a concentration of 40% by weight and hydrofluoric acid and water having a concentration of 50% by weight. An inspection apparatus that optically scans and inspects a test surface of a subject,
A light source that emits light;
Propagates light from the light source, and forms a single-mode optical fiber with a near-field light bleed surface and a normal-propagation light exit surface at the exit, and leaches near-field light at least on the near-field light bleed surface. An optical fiber probe having a conductive thin film for causing
Low-resolution scanning for low-resolution inspection using a normal-propagation light spot formed by normal-propagation light emitted from the normal-propagation light exit surface of this optical fiber probe, and near-field light of the near-field light that exudes from the near-field light extraction surface Scanning means for selectively performing high resolution scanning for high resolution inspection with a light spot on the surface to be examined;
Detection processing means for detecting and processing the inspection light through the test surface,
13. The inspection apparatus according to claim 1, wherein the optical fiber probe is any one of claims 1 to 12. The inspection apparatus according to claim 17, wherein
An inspection apparatus, wherein the light source selectively emits light of different wavelengths according to a low resolution inspection and a high resolution inspection. An inspection method for optically scanning and inspecting a test surface of a subject,
Light transmitted from a light source is guided by the optical fiber probe according to any one of claims 1 to 12, and normal propagation formed by normal propagation light emitted from the normal propagation light exit surface of the optical fiber probe. A low-resolution scan for low-resolution inspection using a light spot and a high-resolution scan for high-resolution inspection using a near-field light spot of the near-field light that oozes from the near-field light bleed surface are applied to the test surface by a scanning means. An inspection method, wherein the inspection method is selectively performed, and the inspection processing light is detected by the detection processing means and the data is processed. The inspection method according to claim 19, wherein
An inspection method characterized by selectively emitting light of different wavelengths from a light source according to a low resolution inspection and a high resolution inspection.

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