JP2004125454A - Near-field spectrometer and method for producing optical fiber probe - Google Patents

Abstract

An object of the present invention is to reduce the influence of background light on a near-field spectrometer.
A light irradiating means for irradiating a laser beam of a predetermined wavelength, an optical fiber probe having a surface coated with a metal or a dielectric and having a fine opening at a tip, and a spectroscopic means for dispersing light emitted by a sample are provided. And a near-field spectrometer that irradiates the sample 22 with the laser light from the optical fiber probe opening as a near field, condenses light emitted from the sample 22 by the near field, and sends the light to the spectroscopic unit 14. ,
A filter 16 for removing a wavelength region including the wavelength of the laser light,
Increasing the light density near the opening of the optical fiber probe 12,
A near-field spectroscopy apparatus characterized in that light emitted from a sample is transmitted through the filter 16 to selectively transmit light accompanying the multiphoton excitation to the spectroscopic means 14.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to near-field spectroscopy devices, and more particularly, to reducing the background light.
[0002]
[Prior art]
In near-field spectroscopy, the surface of an optical fiber whose tip is sharpened is coated with metal or the like, and a fine aperture is formed at the tip in order to irradiate the sample with the near field and condense the emission of the sample by the near field. A probe provided with a section is used. The diameter of the opening is smaller than the wavelength of the light used, and the near field to be irradiated is localized near the opening. For this reason, the near-field spectrometer can measure a minute area exceeding a diffraction limit due to light used (for example, see Non-Patent Documents 1 and 2).
[0003]
[Non-patent document 1]
Satoshi Kawata, Yasushi Inoue “Near-Field and Nonlinear Nanophotonics” “Applied Physics” 2002 Vol. 71, No. 6, p. 653-663
[Non-patent document 2]
Toshihara Saiki, Yoshihito Narita “JSAP International” January 5, 2002, p. 22-29
[Non-Patent Document 3]
Norihiko Nishizawa, Toshio Goto "Generation of ultra-short pulse light with wide wavelength tunable wavelength using nonlinear effect in optical fiber""AppliedPhysics" 2001 Vol. 70, No. 11, p. 1313 to 1316
[Non-patent document 4]
Norihiko Nishizawa, Toshio Goto “Tunable ultrashort pulse fiber laser” “Laser Research” 2001 Vol. 29, No. 2, p. 84-89
[0004]
[Problems to be solved by the invention]
However, there is a problem that light emission due to impurities contained in the optical fiber becomes a background, and overlaps with light emission from the sample, making accurate measurement difficult. For this reason, conventionally, countermeasures such as using an optical fiber with low light emission and selecting a laser wavelength with low light emission have been taken. However, there are problems that an optical fiber having a low light transmittance must be used and that an excitation wavelength required from a sample to be measured cannot be used. Further, among the condensed light, the light emission depending on the characteristics of the sample is extremely fine, and is buried in reflected light or elastically scattered light, making measurement difficult.
An object of the present invention is to improve the near-field spectrometer to reduce the influence of the background as described above.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a near-field spectrometer according to the present invention includes a light irradiation unit that irradiates a laser beam having a predetermined wavelength, and an optical fiber whose surface is covered with a metal or a dielectric and has a minute opening at a tip end. The apparatus includes a probe, spectroscopic means for dispersing light emitted by the sample, and a filter for removing a wavelength region including the wavelength of the laser light. The laser beam is applied to the sample from the opening of the optical fiber probe as a near-field, the light emitted from the sample due to the near-field is collected, sent to the spectroscopic means, and the spectrum is measured. Here, the light density is increased near the opening of the optical fiber probe, and the light emitted from the sample condensed by the optical fiber probe is transmitted through the filter to selectively emit light accompanying the multiphoton excitation. Characterized by sending to means
[0006]
In the above-described near-field spectrometer, the light irradiation means may be variable in wavelength, and the filter may be a filter in which a removal region for removing a predetermined wavelength region including the wavelength of the light source is variable. . It is also preferable that the filter is an interference filter, and that the wavelength region to be removed is changed by changing the angle of incidence of light incident on the interference filter. It is also preferable to provide a plurality of filters having different corresponding wavelength ranges, and to switch between the filters according to the wavelength of light used for measurement.
[0007]
As the optical fiber probe, it is also preferable to use an optical fiber probe having a hollow portion as a light guide path at the center thereof.
An optical fiber serving as a light transmission unit having a light guide path having a diameter larger than the diameter of the light guide path of the optical fiber serving as a probe is provided.The end face of the probe is connected to a core cross section of the light transmission unit, and light from a light source is emitted from the light source. It is also preferable to make the light enter the probe through an optical transmission means.
[0008]
A method of forming an optical fiber having a hollow center portion is a step of forming a sharpened core tip on an end surface of the optical fiber, and a step of coating a metal film or a dielectric film around the optical fiber probe; Forming an opening in the tip portion, and forming a hollow portion in the center of the optical fiber probe by immersing the optical fiber probe having the opening in an etchant for selectively removing the core portion. In.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, attention was paid to light emission accompanying multiphoton excitation in light emission of a sample. In general, the wavelength of light emitted by one-photon excitation is substantially equal to the wavelength of measurement light to be used, and the wavelength of multi-photon excitation is shorter than the wavelength of measurement light. For example, assuming that the wavelength of the measurement light is λ, the wavelength of the light emission due to the two-photon excitation is about λ / 2. However, the probability of occurrence of multiphoton excitation with respect to one-photon excitation is extremely small. For this reason, most of the background light emission from the optical fiber and light emission from the sample become light having a wavelength longer than the incident wavelength, and the irradiation area on the sample is sufficient to measure the light emission due to multiphoton excitation. A large light density is required. In addition, when the light density is high, the intensity of light emission due to multiphoton excitation becomes relatively strong as compared with other collected light.
[0010]
If the light density is low at the part other than the tip of the optical fiber, the background emission due to impurities contained in the optical fiber is mainly one-photon excitation, and the wavelength of the background emission is about the same as the wavelength of the measurement light. It becomes. Most of the collected light is simply reflected light or elastically scattered light from the sample or the tip of the probe, and these lights have the same wavelength as the measurement light. For this reason, by passing the light condensed from the sample through a filter and removing the light in the wavelength region including the wavelength of the measurement laser light, the influence of background light emission can be reduced, and the light emitting portion depending on the properties of the sample can be efficiently used. Can be taken out. Therefore, the background can be reduced regardless of the characteristics of the optical fiber used as the probe.
[0011]
An embodiment of the present invention will be described below with reference to FIG.
The near-field spectrometer shown in FIG. 1 includes a light source 10 for irradiating a pulsed laser as light irradiating means, an optical fiber probe 12 whose surface is coated with a metal or a dielectric, and has a fine opening at the tip, And a filter 16 for removing a predetermined wavelength region. Since the absolute intensity (light density) of the pulse laser can be much higher than that of the CW laser, the pulse laser is used as the light source 10 here.
[0012]
The laser light emitted from the light source 10 is reflected by the half mirror 18, condensed by the lens 20, and enters the end face of the optical fiber probe. The light incident on the optical fiber probe leaks out from the opening at the tip thereof as a near-field, and irradiates the sample 22 with the near-field light. Light emission by near-field light occurs in the sample, and this light emission is collected again from the tip of the probe. The collected light travels in the original direction of the probe 12, passes through the half mirror 18, and enters the filter 16. As shown in FIG. 2, the light incident on the filter 16 removes light in a wavelength range including the wavelength λ of the laser light from the light source, and transmits light in other wavelength ranges. Alternatively, all wavelength regions longer than the wavelength of the measurement light may be removed.
[0013]
FIG. 3 is a conceptual diagram of the core tip 30 of the probe 12. The surface other than the opening 32 is provided with a cover 34 formed of a metal or a dielectric. In addition, the aperture 32 has a small diameter smaller than the wavelength of light, and the light from the light source is condensed in the aperture 32. Therefore, the light density is so large that light emission by multiphoton excitation occurs with sufficient intensity. Is getting bigger. However, except for the tip of the probe 12, the light density is small and there is almost no light emission due to multiphoton excitation. Therefore, by removing the light having the same wavelength as the wavelength of the laser light used for the measurement by the filter, the influence of the background light emission from the optical fiber and the mere reflected light on the measurement is reduced, and the measurement target object is used. It is possible to more accurately measure the luminescence specific to a certain sample.
[0014]
FIG. 4 shows an embodiment in which the light source 110 is a variable-wavelength laser light source in the embodiment of FIG. 1, and the removal area of the wavelength filter 116 is variable according to the wavelength used for measurement. As the wavelength-variable pulse laser light source, for example, a wavelength-variable ultrashort pulse fiber laser or the like described in Non-Patent Documents 3, 4 or the like may be used. The components corresponding to those in FIG. 1 are denoted by reference numeral 100, and description thereof is omitted. In the embodiment of FIG. 4, an interference filter is used as the filter 116. By tilting the tilt of the interference filter 116 with respect to the optical axis, the wavelength removal region is changed as shown in FIG.
[0015]
Further, it is preferable to provide a plurality of filters having different corresponding wavelength regions. By switching to a filter having a removal region corresponding to the wavelength of light used for use measurement and performing measurement, measurement at a wider excitation wavelength can be ensured.
It is also possible to remove background light emission by using a filter having a wide removal region. In this case, by limiting the wavelength change region of the light source to the removal region of the filter, it is possible to remove mere reflected light, elastically scattered light, and the like.
[0016]
It is also preferable to use a probe having a hollow core as shown in FIG. This probe includes a cladding part 40, a covering part 34 formed of a metal or a dielectric, a hollow part 42 as a light guide path at the center, and an opening 32. By using the probe from which the core portion, which is the light guide, is removed, the background light generated in the light guide is eliminated.
[0017]
FIG. 7 is a view showing a process of producing a probe having a hollow portion as a light guide portion from which a core portion is removed. This manufacturing method includes a step of forming a sharpened tip of the optical fiber by chemical etching or the like, and a step of coating a surface of the optical fiber on which the tip is formed with a metal or a dielectric by sputtering or the like. A step of extending the coating of the tip part by a pressing method or the like to form an opening, and a step of removing the core part by a chemical etching method.
[0018]
The step of processing the tip, the covering step, and the opening step are performed according to ordinary procedures. Here, the cladding is SiO ₂ And the core is SiO ₂ GeO ₂ Is used. First, a hydrofluoric acid buffer solution is adjusted to a composition ratio such that the dissolution rate of the clad portion is faster than the dissolution rate of the core portion, and the end face of the optical fiber is immersed in the etching solution. As a result, the clad portion is selectively removed, and a sharpened tip portion is formed in which the core portion protrudes. In addition, the composition ratio of the hydrofluoric acid buffer solution is changed to adjust the relative dissolution rate between the core and the clad, and the shape of the tip is controlled by immersing the optical fiber again in the etching solution. Can be. For example, by preparing an etching solution in which the dissolution rate of the core portion in the clad portion is lower than that of the first etching solution, and immersing the optical fiber in the etching solution, the tip of the core portion becomes the second stage angle. A smaller two-step tapered tip is formed.
[0019]
A metal or dielectric coating is formed on the surface of the optical fiber having the tip portion formed as described above. A minute opening is formed at the tip of the optical fiber coated in this manner. As a method for forming the opening, for example, a pressing method in which the tip is pressed against a flat plate to extend the covering portion to form the opening may be used. In the step of forming the coating, the opening may be formed at the same time by an oblique evaporation method or the like.
[0020]
FIG. 7A shows an optical fiber probe formed as described above. An optical fiber is provided with a coating portion 34 on the surface, and a sharpened core portion 48 protruding from the cladding portion at the end surface forms a tip portion, and a minute opening 32 is provided at the core tip portion. Next, the process proceeds to a step of removing the core portion. The optical fiber is immersed in an etching solution of a hydrofluoric acid buffer solution whose composition ratio is adjusted so that the dissolution rate of the core part 48 is faster than the dissolution rate of the clad part 40. Then, as shown in FIG. 7B, the etching solution permeates through the opening, and the core portion 48 of the optical fiber is selectively removed. Finally, as shown in FIG. 7C, the tip is formed of a metal or dielectric film, and a probe having a hollow portion 42 at the center is formed.
[0021]
In preparing a probe having a hollow central portion, it is desirable to use an optical fiber having a narrow hole at the center from the beginning. Because of this hole, the etching solution easily penetrates into the center of the optical fiber in the step of removing the core portion, and the above-described manufacturing method can be applied to a longer optical fiber. The optical fiber having the above-mentioned hole is formed by heating a hollow glass tube and stretching it. However, as it is, the surface accuracy of the inner surface is poor and the light transmittance as a light guide path is low. Therefore, also in this case, it is necessary to remove the core portion by etching. As described above, the hollow portion is formed at the center of the optical fiber by the chemical etching method, so that the inner surface can be formed with good surface accuracy.
[0022]
The connection between the probe and the optical transmission unit that guides light from the light source to the probe includes a method of directly coupling to the optical fiber and a method of connecting an optical fiber having the same specifications as the probe. In the former case, it was necessary to repeat the optical coupling every time the probe was replaced, which took a long time. In the latter case, the optical loss is large due to the misalignment of the core of the optical fiber, and the transmission efficiency is lowered.
[0023]
Therefore, in the present invention, an optical fiber having a core portion 54 having a diameter larger than the diameter of the core portion 48 of the probe 12 is used as the optical transmission portion 50 as shown in FIG. Here, 52 is a cladding part of the optical transmission unit 50, and 40 is a cladding part of the probe 12. The core portion 48 on the end surface of the optical fiber 12 serving as a probe is brought into close contact with the core portion 54 exposed on the end surface of the optical fiber 50 serving as the optical transmission portion so as to overlap. Since the diameter of the core 54 of the optical transmission unit 50 is sufficiently large, unlike the case where an optical fiber having the same diameter is used for the probe and the optical transmission unit, misalignment of the core hardly occurs, and Loss is reduced. Further, since the core diameter of the optical transmission unit is large, it becomes easy to condense the light from the light source to the optical transmission unit.
[0024]
Some of the light guided from the light source through the light transmission unit 50 to the probe 12 may not be guided to the core 48 of the probe 12 and may be a loss. However, the intensity of the light from the light source is sufficiently high, which is not a big problem as compared with losing minute light due to light emission of the sample.
[0025]
【Example】
FIG. 9 is a conceptual diagram of a preferred embodiment of the present invention. 1 are denoted by reference numeral 200, and detailed description is omitted. Each device of the near-field spectrometer 224 in FIG. 9 is connected to the computer 226, and various settings are performed. For example, setting and starting of spectrum measurement, topographic mapping measurement, spectrum mapping measurement, hardware setting conditions, center wavelength of spectrometer, set temperature of electronically cooled CCD detector, start and end of probe and sample feedback, probe and sample The user can select the coarse movement approach to the sample, the measurement of the resonance frequency of the probe, the start and end of the excitation of the probe at the resonance frequency, and the like from the icons or menus on the window on the display screen of the computer 226 to perform the setting. it can.
[0026]
The filter unit 216 includes a plurality of filters 216 each having a different wavelength range that can be removed. ₁ ~ 216 _n Includes These filters can be switched and used according to the wavelength of light used for measurement.
The light irradiation means 210 includes a plurality of excitation light sources 210 having different characteristics. ₁ ~ 210 _n By operating the motorized optical element, an excitation light source used for measurement can be selected. Further, the separation filter 228 is a filter depending on wavelength or polarization, and by using this separation filter 228, it is possible to switch the excitation light to be used or to use a plurality of light sources at the same time.
[0027]
The filter density of the rotary filter 230 changes according to the rotation angle, and the intensity of light from the light source can be changed in five or more steps according to the rotation angle. It is also preferable to change the intensity of light from the light source more finely by using a plurality of the rotary filters 230. The focusing of the laser light on the probe 212 is performed through an optical fiber 250 which is an optical transmission means.
The correction light source 232 is a standard light source for wavelength correction of the spectral unit 214, and uses a Ne lamp or the like. At the time of wavelength correction, the reflection plate 234 is inserted in the optical path as shown in the figure, and the light of the light source for correction is sent to the spectral means 214.
[0028]
An optical fiber 248 is provided below the sample stage 222 for measurement in an illumination mode for irradiating the sample with a near field from the probe 212 and condensing light transmitted through the sample. The light signal of the optical fiber 248 in the illumination mode is sent to the spectroscopic means 214 by operating an electric optical element. Further, it is desirable to provide a condenser lens between the condenser surface of the optical fiber 248 and the sample.
[0029]
Care must be taken to prevent the optical fiber from being twisted and cut when the sample stage 222 and the optical fiber 248 are attached. Therefore, it is desirable to use an instrument as shown in FIG. The sample stage side mounting tool 78 is mounted below the sample stage. Although the optical fiber 248 is fixed to the fiber-side mounting device 76, the sample-side mounting device 78 and the fiber-side mounting device 76 can rotate with respect to each other. However, the optical fiber 248 is not twisted.
[0030]
A prism such as a right-angle prism or a Dove prism can be placed on the XYZ stage 236 for measurement in a collection mode in which light is irradiated from the lower side of the sample under the condition of total reflection and a near field generated on the sample surface is collected by a probe. . These prisms can rotate 360 degrees horizontally with respect to the sample stage surface 222.
[0031]
The sample stage 222 is attached to an XYZ stage 236. The XYZ stage 236 is connected to a stage controller 238, and can move in the XY directions horizontal to the sample surface and in the Z axis direction perpendicular to the sample surface. it can. The movement of the sample is performed by appropriately switching between coarse movement using a stepping motor or the like for relatively large movement and fine movement requiring precise movement. FIG. 13 shows a dialog displayed on the screen of the computer 226. On the dialog shown in FIG. 13, the drive amount of the XYZ stage 236 is set once, and the XYZ stage 236 is moved in that direction by clicking an arrow button (a portion indicated by a mark in the figure). .
[0032]
Shear force control is used as distance control between the probe 212 and the sample 222. This is performed by vibrating the probe at a resonance frequency and observing a change in frequency resulting from the interaction between the sample and the near field irradiated from the tip of the probe. The probe 212 is vibrated by the vibration means 240 at its resonance frequency. The probe control means 242 irradiates the tip of the probe 212 with light, sends the fluctuation of the reflected light to the stage controller 238 as a feedback signal, and controls the distance between the sample and the probe 212 based on the information.
[0033]
The resonance frequency of the probe to be used is measured as follows. A dialog is displayed on the screen of the computer 226, and the measurement range of the frequency, the measurement interval of the measurement point, the waiting time from the change of the excitation frequency at each measurement point to the measurement, the number of integration of the measurement data, and the like are displayed. Set. The excitation means 240 automatically changes the excitation frequency at the set measurement interval from the minimum value to the maximum value of the set measurement range. From the feedback signal at each measurement point by the probe control means 242, the frequency spectrum in the above measurement range is measured. The maximum point is read from this frequency spectrum, and the frequency of the maximum point can be registered in the storage unit of the computer 226 as the resonance frequency of the probe. After measuring the resonance frequency as described above, the setting of the resonance frequency is performed. By clicking an arrow button or the like on the computer screen with the probe vibrated at the resonance frequency, the vibration frequency can be changed in a preset step. Thereby, fine adjustment of the resonance frequency can be performed.
[0034]
Further, the fine movement of the probe 212 and the sample stage 222 is performed by applying a voltage to the piezo element. A relational expression for calculating the relation between the applied voltage and the actual driving amount of the stage is stored in advance in the storage unit of the computer 226, and the scale for displaying data is changed from the voltage to the actual distance, and vice versa. It is preferable to automatically convert the actual distance to a voltage.
When the probe 212 and the sample stage 222 approach each other, feedback is applied by detecting a change in the resonance frequency of the probe by the probe control means 242 as described above. The setting related to this feedback is performed as follows.
[0035]
First, the magnitude of the feedback signal when the probe and the sample are separated is set as an initial value. In the target value item, the magnitude of the target feedback signal is set when the probe is brought closer to the sample. This target value may be about 10% of the signal strength when the probe and the sample are sufficiently separated. In addition, it is possible to set a signal interval when the feedback signal is intermittently approached without approaching the target value all at once, or to set a waiting time between each movement. After such setting, the probe is automatically brought close to the sample using the coarse movement mechanism and the fine movement mechanism of the XYZ stage 236 until feedback is applied to the sample. Further, the number of times of integration of the feedback signal, the movement interval of the stage, the waiting time between the approaching of the probe and the sample to the capture of the feedback signal, the separation of the probe and the sample using the fine movement mechanism of the XYZ stage 236, It is also possible to set a waiting time for driving the moving mechanism, a waiting time for switching between the coarse moving mechanism and the fine moving mechanism when approaching the probe and the sample, and the like.
[0036]
The CCD detector 244 is connected to the spectroscopy means 214, and the set exposure time and elapsed exposure time, and the set integration time and elapsed integration count are displayed on a window of a computer screen.
The near-field spectrometer 224 has an external input / output trigger function of two or more channels synchronized with an external device, and the synchronization setting can be performed by software. In addition, it is also possible to introduce an optical signal sent from an external device such as a microscope through a multi-mode fiber or the like and operate a motorized optical element into the spectral unit.
[0037]
The settings of the optical system (the light source 210, the sample unit 246, the spectroscopic unit 214, the CCD detector 244, etc.) used for the above-described measurement are displayed on a computer screen as a schematic diagram as shown in FIG. Switching is visually performed by clicking the displayed icon. For example, setting the wavelength and intensity of the light source to be used, introducing the light from the standard light source for wavelength correction to the spectroscope, switching the beam splitter, switching the ND filter etc. to adjust the intensity of the light source, inserting before the spectroscope Setting of a filter to be performed, opening and closing of a shutter provided in front of the light source, activation of a fiber end surface observation monitor for coupling light from the light source to the end surface of the probe, and the like can be performed. In the case of a device that is not mounted, it can be selected as a dummy. The power supply voltage status of these devices can be confirmed, and the result of whether or not the devices operate normally can also be displayed. Further, the apparatus in the near-field spectrometer can be initialized or restarted by software while the software is running.
[0038]
Further, the settings of the optical system, the setting of the optical path, and the measurement conditions such as the intensity and wavelength of the light source can be stored in the computer 226 as a file set by the user or a pattern file prepared in advance. It is also possible to make the above settings based on the information of the file.
Next, mapping measurement in which a probe is moved on a sample surface to perform measurement will be described. The user can set and input the range of the mapping measurement in the X and Y directions and the number of measurement points. In addition, a plurality of measurement conditions can be set in advance, and thereafter, it is possible to automatically perform a plurality of measurements continuously or to perform the measurement based on a time schedule specified in advance.
[0039]
Further, on a dialog as shown in FIG. 15, it is possible to use a bitmap image prepared in advance to set a position of a sample point to be exposed to a near field, an exposure time, and the like. That is, a bitmap image (displayed in a frame 90 in FIG. 15) is read, and the intensity and exposure time of light to be applied to each point of the sample are set according to the color, saturation, or luminance of each point in the image file. I do. For example, white is used as the maximum exposure time, black is used as the minimum exposure time, and the intermediate color is irradiated with light at a point on the sample corresponding to an image point with an exposure time proportional to the gradation.
[0040]
Data such as the mapping measurement and the spectrum mapping measurement measured as described above are stored in the storage unit of the computer 226. These measurement data are displayed as image information as a two-dimensional diagram (see FIG. 16) or a three-dimensional diagram (see FIG. 17) that displays the peak intensity, peak position, peak half width, etc. of the spectrum mapping result on a computer screen. It is displayed and various image processes are performed. As shown in FIGS. 16 and 17, in the two-dimensional and three-dimensional diagrams described above, colors are assigned according to the intensity of the spectrum (spectral mapping measurement), the height of the unevenness of the sample (topographic mapping measurement), and the like.
[0041]
As the image processing, generally well-known processing is possible. For example, contour blurring, contour emphasis, emboss filtering to create a three-dimensional effect, mosaic filter to reduce image resolution, image noise removal, image rotation and inversion, image scaling, color number and color There is a change in degree, a change in RGB intensity, image processing using a filter uniquely defined by the user, and the like.
As a computer process for displaying such two-dimensional or three-dimensional diagram data, one point on XY is designated, and that point is replaced with the average value of the surrounding points. Specify one point sequence parallel to the Y axis, replace each point with the average value of the upper and lower or left and right point sequences, set a threshold value on the Z axis value, and mark all points that exceed the threshold value, There is a method of taking an average value of points around the point and replacing it with the average value.
[0042]
In the above two-dimensional diagram for image measurement, icons or lists for image measurement are displayed inside or outside the window in conjunction with the window, execute the selected image measurement, and calculate the result alone or as a tag. It can be displayed by switching by.
[0043]
A line segment is specified in a two-dimensional diagram for image measurement, which is color-coded according to the intensity of the spectrum, the height of the unevenness of the sample, and the like as in the left diagram of FIG. 18, and a cross section along the line segment is analyzed and displayed. be able to. That is, the end point of the line segment is designated by an icon on the two-dimensional diagram displayed on the screen (the mark x in the left diagram of FIG. 18). Then, a cross-sectional view along the line is displayed as shown in the right diagram of FIG. Set a line segment that specifies the cross-section position, change the length of the line segment, change it by rotation around the center of the line segment, translate the line segment without changing its angle, Changing the length around the center can be performed by dragging the icon.
[0044]
Also, by dragging and dropping a view displaying a plurality of two-dimensional views and three-dimensional views, it is possible to automatically combine the scales as a single view. Here, the data area without the synthesis source is synthesized by filling it with the minimum value of the data of the synthesis source.
[0045]
<Probe holder>
FIG. 11 shows a holder 60 for fixing the probe 12. A hole is formed in the center of the cylindrical holder 60, and the probe 12 is passed through the hole and fixed by bonding, press-fitting, crimping, or the like. The lower part of the holder 60 (on the probe tip side) is a conical body. The upper part of the holder 60 is provided with concentric ears for fixing to the device. Further, it is desirable that the probe 12 be fixed with a fixing agent 62 such as a flexible resin, an adhesive, or a silicon bond. This can prevent the probe from breaking.
[0046]
Further, using two holders, the smaller holder is fixed to the hole of the larger holder by bonding, press-fitting, crimping, or the like so that the upper surface of the inner holder is retracted from the surface of the outer holder. At this time, the hole of the smaller holder is desirably substantially the same as the diameter of the probe 12. As described above, since the shape of the holder 60 is circularly symmetric, vertical distortion of the probe due to temperature and distortion can be eliminated, and vibration of the probe can be made isotropic in the horizontal direction.
[0047]
<Fibre fixed coil>
The figure shows a fixing coil 72 for fixing an optical fiber 74 when wiring the optical fiber in the apparatus. The fixing coil 72 is provided in the apparatus main body 70, and the optical fiber 74 is passed through the coil-shaped fixing coil 72 to fix the path of the optical fiber.
[0048]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the near-field spectroscopy apparatus of this invention, the influence of the background light which arises at the time of a measurement can be reduced regardless of the characteristic of the optical fiber probe used.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a near-field spectrometer of the present invention.
FIG. 2 is a graph showing a wavelength removal region of a filter.
FIG. 3 is a conceptual diagram of a tip portion of an optical fiber probe.
FIG. 4 is a conceptual diagram of the near-field spectrometer of the present invention in a case where the wavelength is variable.
FIG. 5 is a graph showing a wavelength rejection region of a tunable filter.
FIG. 6 is an optical fiber probe having a hollow portion.
FIG. 7 is a method for manufacturing an optical fiber probe having a hollow portion.
FIG. 8 is a diagram showing a connection between a probe and an optical transmission unit.
FIG. 9 is a conceptual diagram of one embodiment of the present invention.
FIG. 10 is a mounting device for an optical fiber.
FIG. 11: Probe holder
FIG. 12 is an optical fiber fixing device.
FIG. 13 shows an example of a display screen of a computer.
FIG. 14 is an example of a display screen of a computer.
FIG. 15 shows an example of a display screen of a computer.
FIG. 16 shows an example of a display screen of a computer.
FIG. 17 shows an example of a display screen of a computer.
FIG. 18 shows an example of a display screen of a computer.
[Explanation of symbols]
10 ... Light irradiation means
12 ... Optical fiber probe
14 ... Spectroscopic means
16 ... Filter

Claims (7)

Light irradiating means for irradiating laser light of a predetermined wavelength, an optical fiber probe whose surface is coated with a metal or a dielectric and having a minute opening at its tip, and spectral means for measuring the spectrum of light emitted by the sample, In the near-field spectroscope, the laser light is irradiated from the optical fiber probe opening to the sample as a near field, and the emission of the sample by the near field is collected and sent to the spectroscopic means.
A filter for removing a wavelength region including the wavelength of the laser light,
Increase the light density near the opening of the optical fiber probe,
A near-field spectroscopy apparatus characterized in that light emitted from a sample is transmitted through the filter to selectively transmit light accompanying the multiphoton excitation to the spectroscopic means. 2. The near-field spectrometer according to claim 1, wherein the light irradiating means has a variable wavelength, and the filter is a filter for removing a predetermined wavelength range including the wavelength of the light source. . 3. The near-field spectrometer according to claim 2, wherein the filter is an interference filter, and a wavelength region to be removed is changed by changing an incident angle of light incident on the interference filter to the interference filter. Near-field spectrometer. 4. The near-field spectrometer according to claim 2, further comprising a plurality of filters having different corresponding wavelength regions, wherein said filters are switched and used according to the wavelength of light used for measurement. Field spectroscopy. 5. The near-field spectrometer according to claim 1, wherein an optical fiber probe having a hollow portion as a light guide path at a center thereof is used as the optical fiber probe. The near-field spectrometer according to claim 1,
An optical fiber serving as light transmission means having a light guide path having a diameter larger than the diameter of the light guide path of the optical fiber serving as a probe is provided.The end face of the probe is connected to a core cross section of the light transmission means, and light from a light source emits light. A near-field spectrometer, which is incident on the probe through an optical transmission unit. Forming a sharpened core tip on the end face of the optical fiber, coating a metal film or a dielectric film around the optical fiber probe, and forming an opening in the tip. In the method of making an optical fiber probe,
A method for producing an optical fiber probe, comprising a step of immersing an optical fiber probe having the opening in an etching solution for selectively removing a core to form a hollow portion in the center of the optical fiber probe.

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