JPWO2008026523A1 - Near-field light measurement method and near-field light measurement device - Google Patents

Abstract

High sensitivity measurement can be performed on a sample that is difficult to measure due to large absorption or scattering in the terahertz wave or millimeter wave band such as moisture, and a two-dimensional image of the sample can be provided. A near-field light measurement method and a near-field light measurement apparatus are provided. Terahertz wave or millimeter wave incident light generated by a light source 11 is converted into parallel light by an optical element section 12, and then intensity-modulated by an optical chopper 24 or the like, condensed by a lens 26, and guided to a waveguide. 13 is incident. The terahertz wave or millimeter wave propagating in the waveguide 13 has a characteristic propagation mode and propagates while generating uniform near-field light on the surface of the waveguide 13. The transmitted light of the terahertz wave or the millimeter wave radiated again from the waveguide 13 to the free space is detected by the pyroelectric element type detector 27a and displayed on the oscilloscope 28. The sample can be arranged within the reach of the near-field light generated on the surface of the waveguide 13 and the sample information can be acquired. [Selection] Figure 1

Description

  The present invention provides a near-field light measurement method and a near-field light measurement capable of performing high-sensitivity measurement on a sample that is difficult to perform normal transmission measurement, such as having large absorption and scattering in the terahertz wave band and the millimeter wave band. Relates to the device.

  As a method included in the Fourier transform infrared spectrophotometer (FT-IR), there is a total reflection absorption measurement method (ATR method), and the ATR method has the advantage that it can be measured without subjecting the sample to chemical or physical treatment. . On the other hand, in recent years, engineering applications of the terahertz wave band, which is an electromagnetic wave located between light and radio waves, have been actively performed.

  The terahertz wave band may be able to analyze an object that could not be analyzed by conventional infrared light or X-rays. For example, chemicals in envelopes and opaque plastics are difficult to detect even using infrared light or X-rays, but can be analyzed using terahertz wave electromagnetic waves (for example, Patent Document 1). 2).

  However, since terahertz waves and millimeter waves are strongly absorbed by water, it is necessary to solidify the sample by a frozen powder method or the like when analyzing a sample containing a large amount of moisture. In response to this problem, a terahertz wave-ATR method that enables measurement of a liquid sample by using near-field light of a terahertz wave has been reported (for example, see Patent Document 3 and Non-Patent Documents 1 and 2).

  In addition, as a method for efficiently generating near-field light, cases relating to propagation modes in a waveguide have been reported for electromagnetic waves in the visible light to near-infrared light region. That is, a propagation mode in which the propagation mode inside the waveguide can be determined from the intensity distribution of the light after passing through the waveguide and the near-field light is efficiently generated is known. At this time, it has also been reported that the waveguide has an inner diameter or a width of about 10 to 1000 times the wavelength of incident light (see, for example, Non-Patent Documents 3 and 4).

JP 2004-286716 A JP 2005-114413 A JP 2004-354246 A Hideki Hirori and 2 others, “Time-domain terahertz ATR spectroscopy”, Spectroscopic Research, The Spectroscopical Society of Japan, 2004, Vol. 53, No. 6, p.361-364 Hideki Hiromi and three others (H. Hiroi, K. Yamashita, M. Nagai and K. Tanaka), “Attenuated Total Reflection Spectroscopy in Time Domain Using Terahertz Coherent Pulses), Japanese Journal of Applied Physics (Jpn.J.Appl.Phys.), Japan Society of Applied Physics, 2004, Vol. 43, No. 10A, L1287-L1289 J.J. Degnan, “The Waveguide Laser: a Review”, App. Phys., (USA), 1976, 11, 11, 1-31 JJ Degnan, “Waveguide Laser Mode Patterns in the Near and Far Field”, Applied Optics (USA), 1973, No. Volume 12, Issue 5, pp.1026-1033

  The present invention is a near-field optical measurement capable of performing high-sensitivity measurement on a sample that is difficult to perform normal transmission measurement, such as a sample containing a lot of moisture, such as a large absorption or scattering in a terahertz wave or millimeter wave band. It is an object to provide a method and a near-field light measurement device. Furthermore, it aims at providing the two-dimensional image and three-dimensional image of a sample.

  In order to achieve the above object, a near-field optical measurement method according to the present invention propagates terahertz wave or millimeter wave incident light generated by a terahertz wave or millimeter wave light source to a waveguide, and Information on a sample arranged within the reach of the near-field light is obtained by near-field light generated outside.

  The near-field light measurement method according to the present invention can obtain information on a sample arranged within the reach of the near-field light using near-field light of terahertz waves or millimeter waves. Since near-field light of terahertz waves or millimeter waves is used, it is possible to obtain information on a sample that is difficult to perform normal transmission measurement, such as having large absorption or scattering particularly in the terahertz wave band or millimeter wave band. Further, non-destructive and non-invasive measurement of the periphery of the sample surface can be performed with terahertz wave or millimeter wave near-field light. Terahertz waves or millimeter wave band electromagnetic waves have the property of being strongly absorbed by water, but according to the near-field light measurement method according to the present invention, they contain a large amount of water such as living tissue, food, and water-soluble amino acids. Even a sample can be measured with high sensitivity without being affected by water absorption.

  Terahertz or millimeter wave light sources include, for example, backward wave tubes, terahertz wave parametric light sources, gun oscillators, impatting oscillators, tannet oscillators, photoconductive switch excitation with ultrashort pulse lasers, quantum cascade lasers, p-Ge lasers, free It consists of an electronic laser. Waveguides, such as silicon single crystals, Teflon (registered trademark), plastic materials, quartz glass, ceramics, metal oxides, and semiconductors, have a small absorption coefficient in the terahertz wave or millimeter wave band, and have a refractive index that is higher than that of the sample to be measured. It is preferable that it is comprised with a high thing.

  In general, terahertz waves are electromagnetic waves having a frequency of 0.1 to 10 THz and a wavelength of 30 μm to 3 mm. The millimeter wave is an electromagnetic wave having a frequency of 30 to 300 GHz and a wavelength of 1 to 10 mm.

  In the near-field light measurement method according to the present invention, it is preferable to obtain information on the sample by detecting transmitted light that has passed through the waveguide. In this case, information on the sample can be obtained by measuring the intensity or intensity change of the transmitted light.

  In the near-field light measurement method according to the present invention, the waveguide is tubular, has an inner diameter of 6 to 1000 times the wavelength of the incident light, and the near-field light depends on a characteristic propagation mode of the incident light, Preferably, it occurs near the surface of the waveguide. In this case, uniform near-field light can be generated in the vicinity of the waveguide surface by the characteristic propagation mode of the incident light, and measurement with high sensitivity and high accuracy is possible. The tubular waveguide refers to a dense cylindrical shape inside rather than a cavity, and the cross-sectional shape thereof may be a circle, an ellipse, a rectangle, a polygon, or the like.

  In the near-field light measurement method according to the present invention, the sample may be made of a liquid, powder, solid, gel substance, or gas, and information on the sample may be continuously measured. In this case, temporal and spatial changes in sample information can be obtained.

  The near-field light measurement method according to the present invention may be capable of spectroscopic measurement by changing the wavelength of the incident light or by dispersing the transmitted light with respect to the broadband incident light. In this case, the chemical substance contained in the sample and the structure of the substance can be specified.

  The near-field light measurement method according to the present invention may be capable of measuring the shape of the sample from a change in intensity of the transmitted light by changing a relative position between the sample and the waveguide. In this case, a two-dimensional image of the sample can be obtained from the measured shape of the sample. Further, as a method of changing the relative position between the sample and the waveguide, for example, a method of scanning by moving the sample along the waveguide, moving the waveguide along the surface of the sample, There is a method of moving the waveguide close to or away from each other. By combining these, not only the two-dimensional shape of the sample but also a three-dimensional shape can be obtained, and a three-dimensional image of the sample can also be obtained.

  In the near-field light measurement method according to the present invention, the waveguide may have a curvature along the propagation direction of the incident light. In this case, the shape of the waveguide can be matched to the shape of the sample and the measurement situation, and efficient measurement can be performed. In addition, since the interaction area between the sample and the near-field light can be expanded, highly sensitive measurement is possible. The curvature of the waveguide is preferably in a range where the characteristic propagation mode of incident light does not change.

  A near-field light measuring device according to the present invention includes a terahertz wave or millimeter wave light source, a waveguide provided so that the terahertz wave or millimeter wave incident light from the light source can be propagated, and generated outside the waveguide. And a detection unit that detects transmitted light that has passed through the waveguide so as to acquire information on a sample disposed within the reachable range of the near-field light.

  The near-field light measurement apparatus according to the present invention is used to implement the near-field light measurement method according to the present invention. The near-field light measurement apparatus according to the present invention can obtain information on a sample disposed within the reach of the near-field light using terahertz wave or millimeter-wave near-field light. Since near-field light of terahertz waves or millimeter waves is used, it is possible to obtain information on a sample that is difficult to perform normal transmission measurement, such as having large absorption or scattering particularly in the terahertz wave band or millimeter wave band. Further, non-destructive and non-invasive measurement of the periphery of the sample surface can be performed with terahertz wave or millimeter wave near-field light. In the near-field light measuring apparatus according to the present invention, it is preferable that the waveguide is tubular and the near-field light is generated near the surface of the waveguide. In addition, the tubular waveguide means that the inside is not a hollow but a dense cylinder, and the cross-sectional shape thereof may be a circle, an ellipse, a rectangle, a polygon, or the like.

  The near-field light measuring apparatus according to the present invention is a moving means provided to be able to move the sample or the waveguide so as to change the relative position between the sample and the waveguide within the reach of the near-field light. When the transmitted light is detected by the detection unit while moving the sample or the waveguide by the moving means, the shape of the sample is measured from a change in the intensity of the transmitted light, and a two-dimensional image or You may have the analysis means to display with a three-dimensional image. In this case, a two-dimensional image or a three-dimensional image of the sample can be obtained from the measured shape of the sample. The moving means may be any means as long as it can change the relative position between the sample and the waveguide within the reach of the near-field light, and the sample can be moved along the waveguide. Alternatively, the waveguide may be made of a material that moves the waveguide along the surface of the sample, or a material that moves the sample and the waveguide closer to or away from each other.

  According to the present invention, a near-field capable of performing high-sensitivity measurement on a sample that is difficult to perform normal transmission measurement, such as a sample containing a large amount of moisture, such as a large absorption or scattering in the terahertz wave or millimeter wave band. An optical measurement method and a near-field light measurement device can be provided. In addition, two-dimensional and three-dimensional images of the sample can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 18 show a near-field light measuring method and a near-field light measuring apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the near-field light measurement apparatus 10 includes a light source 11, an optical element unit 12, a waveguide 13, and a detection unit 14.

  The light source 11 can generate a terahertz wave and a millimeter wave, and includes a backward wave tube. In the example shown in FIG. 1, the light source 11 generates a continuous wave having a frequency of about 1 THz with an output of about 1 mW.

  The optical element section 12 includes an optical light source 21 for optical adjustment, a glass plate 22 with an ITO film, an off-axis parabolic mirror 23, an optical chopper 24, a wire grid 25, and a lens 26. The ITO film-attached glass plate 22 is arranged so that light from the optical adjustment light source 21 can be transmitted straight, and incident light from the light source 11 can be reflected by about 90 degrees. The glass plate 22 with an ITO film can be adjusted so that the propagation direction of incident light from the light source 11 matches the propagation direction of light from the light source 21 for optical adjustment. The off-axis paraboloidal mirrors 23 are arranged so as to form an optical path for making incident light from the light source 11 parallel light and guiding the incident light to the waveguide 13. The optical chopper 24 is provided near the middle of the optical path and is configured to modulate the intensity of incident light. The wire grid 25 is provided near the end of the optical path, and is configured to transmit a part of incident light and reflect the rest by 90 degrees. The lens 26 is disposed so as to collect incident light transmitted through the wire grid 25 and guide the incident light into the waveguide 13.

  The waveguide 13 is made of a cylindrical silicon crystal having a small absorption coefficient in the terahertz wave and millimeter wave bands and a higher refractive index than the sample to be measured. The waveguide 13 is provided so that incident light from the light source 11 that has passed through the lens 26 can propagate from one end to the inside. When the wavelength of incident light is 0.3 mm (frequency: 1 THz), the waveguide 13 has an inner diameter of 2 mm (waveguide with a refractive index of 3.4), and the wavelength of incident light is 3 mm (frequency: 0.1 THz). The inner diameter is 20 mm (waveguide with a refractive index of 1.6), and the inner diameter is about 7 times the wavelength of incident light. When the wavelength of incident light is 0.3 mm (frequency: 1 THz), the generation of near-field light has been confirmed using a waveguide having an inner diameter of 5 mm (about 17 times the wavelength of incident light). Although it depends on the refractive index and shape of the waveguide, in principle, the limit of the inner diameter of the waveguide is ½ of the wavelength of the incident light, so the inner diameter is about 0.5 times the wavelength of the incident light. Near-field light can be generated even when a waveguide having the same is used.

  The detection unit 14 includes two pyroelectric element type detectors 27 a and 27 b, an oscilloscope 28, and a computer 29. One pyroelectric element type detector 27 a is arranged on the other end side of the waveguide 13 and can detect transmitted light that has passed through the waveguide 13. The other pyroelectric element type detector 27b is arranged to detect the reference light reflected by the wire grid 25. The oscilloscope 28 is connected to the pyroelectric element type detectors 27a and 27b, and can display the transmitted signal of the transmitted light and the reference signal of the reference light detected by the pyroelectric element type detectors 27a and 27b. . The computer 29 is connected to the oscilloscope 28 and can be analyzed by inputting a transmission signal and a reference signal.

  The near-field light measurement method of the embodiment of the present invention can be implemented by the near-field light measurement apparatus 10. The incident light of the terahertz wave or millimeter wave generated by the light source 11 is converted into parallel light by the optical element unit 12 such as the off-axis paraboloidal mirror 23, and then subjected to intensity modulation by the optical chopper 24 and collected by the lens 26. Light is incident on the waveguide 13. The terahertz wave or millimeter wave propagating in the waveguide 13 has a characteristic propagation mode and propagates while generating uniform near-field light in the vicinity of the outer surface which is the surface of the waveguide 13. The transmitted light of the terahertz wave or the millimeter wave radiated again from the waveguide 13 to the free space is detected by the pyroelectric element type detector 27a and displayed on the oscilloscope 28 or the computer 29. The sample information can be obtained by arranging the sample within the reach of the near-field light generated on the surface of the waveguide 13 and measuring the intensity or intensity change of the transmitted light that has passed through the waveguide 13. it can.

  Since the near-field light measurement method and the near-field light measurement apparatus 10 according to the embodiment of the present invention use near-field light of terahertz waves or millimeter waves, the terahertz wave band or millimeter wave band has large absorption or scattering. Thus, it is possible to obtain information on a sample that is difficult to perform normal transmission measurement. Further, non-destructive and non-invasive measurement of the periphery of the sample surface can be performed with terahertz wave or millimeter wave near-field light. For this reason, although the terahertz wave or millimeter wave band electromagnetic wave has a property of being strongly absorbed by water, according to the near-field light measurement method and the near-field light measurement device 10 of the embodiment of the present invention, Even a sample containing a large amount of water such as a living tissue, food, or a water-soluble amino acid can be measured with high sensitivity without being affected by water absorption.

  The near-field light measurement method and the near-field light measurement apparatus 10 according to the embodiment of the present invention can generate uniform near-field light on the surface of the waveguide 13 by the characteristic propagation mode of incident light, and have high sensitivity. In addition, highly accurate measurement is possible. In addition, information on a sample made of a liquid, powder, solid, gel substance or gas can be obtained. By measuring sample information continuously, temporal and spatial changes in sample information can be obtained.

  As a sample to be measured, an organic compound, an inorganic compound, a metal, a ceramic, or the like can be considered. For example, organic polymers such as plastics, engineering products such as pipes, PVC pipes, electric wire coatings, nucleic acids (DNA, RNA), amino acids, peptides, proteins, lectins, antibodies, sugar chains, vitamins, hormones, environmental hormones, cells Examples include viruses, allergic components, in vivo components such as blood, lymph, and bone marrow fluids, biological tissues, foods such as fruits and vegetables, pharmaceuticals, and cosmetics.

  FIG. 2 shows the concentration dependence of the aqueous sugar solution of the terahertz wave intensity transmitted through the waveguide 13 measured by the near-field light measurement method and the near-field light measurement apparatus 10 according to the embodiment of the present invention. The frequency of incident light is about 1 THz, and the aqueous sugar solution is an aqueous glucose solution. As shown in FIG. 2, it is observed that the transmittance of the terahertz wave monotonously increases as the glucose concentration increases.

  As described above, the near-field light measurement method and the near-field light measurement apparatus 10 according to the embodiment of the present invention can measure the amount of water and the concentration of the aqueous solution around the waveguide 13. For this reason, it is possible to measure a sample with high absorption, which has been difficult to measure in the past with high sensitivity, and because the interaction area with the sample can be made larger than the THz-ATR method using near-field light in the same way, it is highly sensitive. Can be achieved.

  FIG. 3 shows the relationship between the length of the sample and the change in transmitted light intensity when a paper (sample) infiltrated with water as the sample 1 is placed around the waveguide 13. In addition, the frequency of incident light is about 1 THz. As shown in FIG. 3, it has been observed that the transmittance decreases as the portion in contact with the waveguide 13 becomes longer.

  FIG. 4 shows the transmittance when water or a sugar aqueous solution having a concentration of 50% is infiltrated into a paper having a width of about 6 cm as the sample 1 and the paper is wound around the waveguide 13. A Teflon (registered trademark) rod having an inner diameter of 1.2 cm and a length of 30 cm was used as the waveguide 13, and a millimeter wave with a frequency of 94 GHz was used as incident light. As shown in FIG. 4, it was confirmed that the sugar aqueous solution had a higher transmittance than water. From the results of FIGS. 2 to 4, the near-field light measurement device 10 can measure the amount of water and the concentration of the aqueous solution around the waveguide 13.

  As shown in FIGS. 5 to 12, the waveguide 13 is not limited to a columnar shape, and may be made of a material having a curvature along the propagation direction of incident light within a range in which the characteristic propagation mode does not change. . In this case, the shape of the waveguide 13 can be matched with the shape of the sample 1 and the measurement situation, and efficient measurement can be performed. In addition, since the interaction area between the sample 1 and the near-field light can be expanded, highly sensitive measurement is possible. Note that the curvature that the waveguide 13 may have depends on the refractive index of the waveguide 13.

  FIG. 5 shows a biological information measurement system using the near-field light measurement device 10. As shown in FIG. 5, the waveguide 13 has a mechanism that has a curvature to such an extent that the standing wave is not disturbed inside, and thereby the area of interaction with the object that is the sample 1 can be expanded. Even slight changes can be measured with high sensitivity. Although the coiled waveguide 13 is shown in FIG. 5, it is possible to adopt a U-shaped or S-shaped configuration according to the object and measurement conditions. The terahertz wave and millimeter wave that have propagated through the waveguide 13 are detected by a detector such as a pyroelectric element type detector 27a as transmitted light together with information on the object obtained by the near-field light.

  When the object is a living body, it is possible to obtain information on the depth direction in which the outer skin of the living thing or fruit and fruit and the near-field light that are in close contact with the waveguide 13 are soaked, so that changes such as biological water, blood, and fruit juice are obtained. be able to. Therefore, it is possible to non-invasively moisturize the skin, change blood components, and in the case of agricultural products, evaluate the freshness and quality, and further determine non-destructive internal damage.

  FIG. 6 shows a method for determining the experimental results obtained in the experimental system of FIG. For example, when the moisture of the measurer's skin increases, the amount of moisture in the subcutaneous layer increases, so that the near-field light that penetrates the waveguide 13 is absorbed, and the amount of transmission obtained by the pyroelectric element type detector 27a decreases. To do. By using such results, it becomes possible to non-invasively measure the efficacy of pharmaceuticals and cosmetics, changes in blood components, and the like.

  FIG. 7 shows a nondestructive inspection system for industrial products and the like using the near-field light measuring device 10. FIG. 7 is a non-destructive inspection of an internal defect of a tubular member made of a material that transmits terahertz waves or millimeter waves. In addition, this method can be introduce | transduced other than tubular members, such as a board | plate material, by selecting the shape of the waveguide 13 matched with the shape of the measuring object. In order to increase the working area with respect to the measurement target portion, the waveguide 13 can also have a mechanism having a curvature to such an extent that the standing wave is not disturbed inside. FIG. 7 shows a configuration in which the object that is the sample 1 moves so as to be in contact with the bent waveguide 13, and when the movement of the object is difficult, a configuration in which the waveguide 13 can be moved is also possible. It is. The terahertz wave or millimeter wave transmitted light propagated through the waveguide 13 is detected by a detector such as a pyroelectric element type detector 27a.

  FIG. 8 shows a measurement site of a pipe cross section which is the sample 1 by the nondestructive inspection system of FIG. In the measurement method using the near-field light measurement device 10, the near-field light 13 a having a permeation depth of about the wavelength is formed around the waveguide 13. Non-destructive monitoring is possible as permeation change. The measurement may be performed by moving one waveguide 13 along the pipe, or may be performed by arranging a plurality of waveguides 13 along the pipe. In addition, the waveguide 13 may be measured in the form of a coil. In this case, since the active area of the near-field light can be widened, there is an effect that a slight change in the object can be monitored with high accuracy. FIG. 9 shows a method for determining an abnormal part from the result obtained at this time. When there is no abnormality in the object, an arbitrary amount of transmission is shown. However, when the object moves and there is an abnormal part, the amount of transmission changes. By comparing this amount of change with a threshold value, the opaque pipe can be inspected.

  FIG. 10 shows a reaction monitoring method for the solution, which is the sample 1, using the near-field light measurement apparatus 10. The generated terahertz wave or millimeter wave is condensed on the end face of the waveguide 13 by the condenser lens 26 and is coupled to the waveguide 13 at the beam waist. As shown in FIG. 10, in order to take a large area of action with the measurement target portion, the waveguide 13 can also have a mechanism having a curvature to such an extent that the standing wave is not disturbed inside. The waveguide 13 is composed of a member having a higher refractive index than that of the solution, and propagates in the lowest order mode inside. As a result, near-field light oozes out of the entire waveguide 13. The terahertz wave and millimeter wave bands are bands that absorb large amounts of water, unlike visible light. Therefore, monitoring the increase and decrease of water molecules due to hydrolysis in, for example, enzymatic reactions in protein solutions, from changes in the leaked near-field light. It becomes possible to do. FIG. 11 shows a method for monitoring the enzyme reaction of the protein solution. When enzyme A is used, it can be determined that the reactivity is higher than that of enzyme B. A combination of these results and LC / MS (liquid chromatography / mass spectrometry) enables high-efficiency production of any peptide.

  In this way, by using near-field light, it is possible to measure a reaction in an aqueous solution that is difficult in the terahertz wave and millimeter wave bands, and further to measure the reaction with high sensitivity by changing the shape of the waveguide 13. It becomes possible. Furthermore, as shown in FIG. 12, as a method in which the waveguide 13 is not disposed in the liquid that is the sample 1, it is possible to closely contact the outer periphery of the container 2. At this time, the container 2 is preferably capable of transmitting terahertz waves and millimeter waves. Thereby, since it can take the structure which does not contact a sensing part directly to a reaction layer (object), it becomes possible to prevent washing and contamination.

FIG. 13 shows the results of measuring the change in transmittance over time with respect to the antigen-antibody reaction in real time by the interaction (binding) between biotin and avidin. Since biotin cannot be directly bonded to the waveguide 13 composed of a silicon rod, the waveguide 13 is first immersed in a biotin-labeled BSA solution and then crosslinked with glutaraldehyde, and biotin-labeled BSA is applied to the surface of the waveguide 13. Immobilized. In this state, the experimental system was constructed and the measurement was started at 0 seconds in FIG.
Next, a buffer in which BSA is dissolved is filled around the waveguide 13. At this time, the transmittance rapidly decreases due to absorption by the buffer (particularly water).
Next, the BSA in the solution gradually adheres to the surface of the waveguide 13 so that it is replaced with water molecules. Since water absorbs more than BSA, the transmittance gradually increases as shown in FIG.
Next, avidin is added dropwise at 3500 seconds. As a result, biotin and avidin on the surface of the waveguide 13 are bonded to each other, and as shown in FIG. 13, the absorption of avidin existing in the near-field light leakage region (interaction space) on the surface layer of the waveguide 13. A decrease in transmittance is observed. As described above, the near-field light measurement apparatus 10 can measure a change in transmittance with time in response to an antigen-antibody reaction in real time.

  In addition, by immobilizing a compound that specifically binds to bacteria and viruses in the waveguide 13, the bacteria and viruses can be observed. For example, since milk collected from dairy cows with mastitis contains inflammatory cells due to mastitis, the number of cells is measured by the near-field light measurement device 10 to improve the safety of milk. Can be secured.

  FIG. 14 shows the result of spectroscopic measurement performed on the aqueous solution of water and monosaccharide by changing the wavelength of incident light. The monosaccharide aqueous solutions were three types of aqueous solutions of mannose, glucose, and fructose, and the frequencies of incident light were 0.93 THz and 0.96 THz. As shown in FIG. 14B, a cylindrical silicon crystal is passed as a waveguide 13 in a plastic container 3, and water or each aqueous solution sample 1 is placed in the container 3 so that the waveguide 13 is immersed. Satisfied and measured.

  As shown in FIG. 14A, it was confirmed that at 0.93 THz, only the transmittance of mannose was low and the absorption was large. In the case of powder, mannose is known to have absorption in the vicinity of 0.93 THz, which agrees with this result. At 0.96 THz, it was confirmed that the transmittance of the three types of monosaccharide aqueous solutions was almost the same. Until now, there has been no measurement of the spectrum of each aqueous solution, and it has been confirmed that the spectrum of a liquid sample can be obtained by the near-field light measurement method and the near-field light measurement apparatus 10 of the embodiment of the present invention. It was. In addition, it is considered that long sugar chains such as oligosaccharides and other liquid samples can be analyzed by changing the wavelength of incident light.

  As shown in FIG. 15, the near-field light measurement apparatus 10 has a moving means 31 composed of a rotary stage, and the sample 1 is placed on the rotary stage and rotated to rotate the sample 1 and the waveguide 13 relative to each other. The position may be changed. At this time, the transmitted light is detected by the pyroelectric element type detector 27a of the detection unit 14 while rotating the sample on the rotating stage, and the shape of the sample 1 is measured by the computer 29 of the analyzing means from the change in the transmitted light intensity. Thus, a two-dimensional image or a three-dimensional image can be displayed. The moving means 31 may be anything as long as it can change the relative position between the sample 1 and the waveguide 13 within the reach of near-field light.

  Until now, image reconstruction using terahertz waves and millimeter waves has limited measurement objects because the terahertz waves and millimeter waves do not travel straight due to the effects of refractive index distribution and scattering. On the other hand, as shown in FIG. 15, by using the waveguide 13, information on the relative positions of the sample 1 and the waveguide 13 and the respective information can be obtained without being affected by the refractive index distribution or scattering of the sample 1. Image reconstruction is possible from the transmitted light intensity at the position. For image reconstruction, methods such as radon transformation and radon inverse transformation can be used.

  Further, spectroscopic measurement can be performed by changing the wavelength of incident light or by dispersing transmitted light by broadband incident light. FIG. 16 shows the result of spectroscopic measurement performed on a sample having a thickness of 1 mm. As shown in FIG. 16, for example, when the wavelength of incident light is 1 THz, the transmittance is about 9%, and even a sample having a predetermined thickness uses near-field light of terahertz waves and millimeter waves. It was confirmed that spectroscopic measurement was possible. By introducing such near-field spectroscopy, spectral imaging becomes possible. As a result, it becomes possible to specify the substance and the structure of the substance by imaging the sample, such as chemical substances in the envelope, tissue diagnosis under the skin, fruit and vegetable inspection, and industrial material inspection.

  FIG. 17 shows the result of measuring the intensity change of the transmitted light by moving the rectangular plate-shaped sample 1 in the direction perpendicular to the length direction of the waveguide 13. In addition, the frequency of incident light is about 1 THz. As shown in FIG. 17, a clear change in transmittance was confirmed both when the sample 1 was moved along its long side direction and when the sample 1 was moved along its short side direction. FIG. 18 shows the result of measuring the shape of the sample 1 by the computer 29 based on the result of FIG. 17 and displaying it as a two-dimensional image. As shown in FIG. 18, it was confirmed that the planar shape of the sample 1 was accurately reproduced. As described above, according to the near-field light measurement method and the near-field light measurement apparatus 10 according to the embodiment of the present invention, a two-dimensional image or a three-dimensional image of the sample 1 can be obtained.

  In FIG. 19, a polyethylene plate whose thickness changes from 1 mm to 2 mm in the middle is used as the sample 1, and transmitted light when the sample 1 is moved in the direction perpendicular to the axial direction of the waveguide 13. The result of measuring the intensity change is shown. In addition, the frequency of incident light is about 1 THz. As shown in FIG. 19, it was confirmed that the intensity also changed at the position where the thickness of the sample 1 changed. Therefore, according to the near-field light measurement method and the near-field light measurement apparatus 10 of the embodiment of the present invention, the two-dimensional shape of the sample 1 can be measured, and a two-dimensional image of the sample 1 is obtained from the shape. be able to. Note that the change in intensity after the change in thickness is considered to be due to the influence of scattering at the edge portion of the sample 1.

1 is an overall configuration diagram illustrating a near-field light measurement device according to an embodiment of the present invention. It is a graph which shows the aqueous solution density | concentration dependence of the transmittance | permeability of a terahertz wave of the near-field light measuring method and near-field light measuring device of embodiment of this invention. It is a graph which shows the sample length dependence of the transmittance | permeability of a terahertz wave of the near-field light measuring method and near-field light measuring device of embodiment of this invention. It is a graph which shows the transmittance | permeability of the millimeter wave with respect to water and a 50% concentration sugar aqueous solution of the near-field light measuring method and near-field light measuring device of embodiment of this invention. It is a perspective view which shows the example of application to the biological information measurement system of the near-field light measuring method and near-field light measuring device of embodiment of this invention. It is a graph which shows the determination method of the experimental result of the biometric information measurement system shown in FIG. It is a perspective view which shows the example of application to the nondestructive inspection systems, such as industrial products, of the near-field light measuring method and the near-field light measuring device of embodiment of this invention. It is sectional drawing which shows the use condition of the nondestructive inspection system shown in FIG. It is a graph which shows the method of determining an abnormal part from the experimental result of the nondestructive inspection system shown in FIG. It is a perspective view which shows the application example to the reaction monitoring method of the solution thing of the near-field light measuring method and the near-field light measuring device of embodiment of this invention. It is a graph which shows the method of monitoring the enzyme reaction of the protein solution by the reaction monitoring method shown in FIG. It is a side view which shows the example of application to the measurement of the target object in a container of the near-field light measuring method and the near-field light measuring device of embodiment of this invention. It is a graph which shows the time change of the transmittance | permeability with respect to an antigen antibody reaction of the near-field light measuring method and near-field light measuring device of embodiment of this invention. (A) A graph showing a result of spectroscopic measurement for a liquid sample, and (b) a perspective view showing a method for spectroscopic measurement of a liquid sample in the vicinity of the waveguide of the near-field light measuring method and the near-field light measuring device according to the embodiment of the present invention. It is. It is a block diagram which shows the modification which has a moving means of the near-field light measuring device shown in FIG. It is a graph which shows the spectroscopic measurement result of the near-field light measuring method and the near-field light measuring device of embodiment of this invention. In the near-field light measurement method and near-field light measurement apparatus according to the embodiment of the present invention, (a) a rectangular plate-shaped sample is moved along the long side direction in a direction perpendicular to the length direction of the waveguide. (B) A change in transmittance when a rectangular plate-shaped sample is moved in the direction perpendicular to the length direction of the waveguide along its short side direction. It is a graph which shows. It is an analysis figure which shows the result of having measured the shape of the sample from the result of FIG. 17, and displaying it as a two-dimensional image. (A) graph showing intensity change of transmitted light with respect to thickness of sample, (b) perspective view of sample, (c) with respect to waveguide of near-field light measurement method and near-field light measurement device of embodiment of the present invention It is a side view which shows the movement state of a sample.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample 10 Near-field light measuring device 11 Light source 12 Optical element part 13 Waveguide 14 Detection part 21 Optical adjustment light source 22 Glass plate with ITO film 23 Off-axis parabolic mirror 24 Optical chopper 25 Wire grid 26 Lens 27a, 27b Focus Electric element type detector 28 Oscilloscope 29 Computer

[0002]
Patent Document 2: Japanese Patent Application Laid-Open No. 2005-114413 Patent Document 3: Japanese Patent Application Laid-Open No. 2004-354246 Non-Patent Document 1: Eihiro Hirori and two others, “Time Domain Terahertz ATR Spectroscopy”, Spectroscopic Research, Japan Spectroscopic Society, 2004, Vol. 53, No. 6, p. 361-364
Non-Patent Document 2: Eihiro Hirori and three others (H. Hiroi, K. Yamashita, M. Nagai and K. Tanaka), “Attenuated Total Reflection Spectroscopy in Time Domain Using Terahertz Coherent Pulse (Attenuated Total) Reflection Spectroscopy in Time Domain Usage Terahertz Coherent Pulses), Japanese Journal of Applied Physics (Jpn. J. Appl. Phys.), Japan Applied Physics Society, 2004, L, No. 89, L43.
Non-Patent Document 3: J. Jegnan, "The Waveguide Laser: a Review", Applied Phys. (App. Phys.), 1976, 11th. Volume, p. 1-33
Non-Patent Document 4: JJ Degnan, “Waveguide Laser Mode Patterns in the Near and Far Field”, Applied Optics (App. Opt.). (USA), 1973, Vol. 12, No. 5, pp. 1026-1033
DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention [0007]
The present invention is a near-field optical measurement capable of performing high-sensitivity measurement on a sample that is difficult to perform normal transmission measurement, such as a sample containing a lot of moisture, such as a large absorption or scattering in a terahertz wave or millimeter wave band. It is an object to provide a method and a near-field light measurement device. Furthermore, it aims at providing the two-dimensional image and three-dimensional image of a sample.
Means for Solving the Problems [0008]
In order to achieve the above object, the near-field optical measurement method according to the present invention uses a terahertz wave or millimeter wave incident light generated by a terahertz wave or millimeter wave light source, and has an absorption coefficient in the terahertz wave or millimeter wave band. The waveguide is small, has a higher refractive index than the sample to be measured, is tubular, and has an inner diameter that is 6 to 1000 times the wavelength of the incident light. The near-field light generated near the surface of the

[0003]
Information on the sample arranged within the reach of near-field light is obtained.
[0009]
The near-field light measurement method according to the present invention can obtain information on a sample arranged within the reach of the near-field light using near-field light of terahertz waves or millimeter waves. Since near-field light of terahertz waves or millimeter waves is used, it is possible to obtain information on a sample that is difficult to perform normal transmission measurement, such as having large absorption or scattering particularly in the terahertz wave band or millimeter wave band. Further, non-destructive and non-invasive measurement of the periphery of the sample surface can be performed with terahertz wave or millimeter wave near-field light. Terahertz waves or millimeter wave band electromagnetic waves have the property of being strongly absorbed by water, but according to the near-field light measurement method according to the present invention, they contain a large amount of water such as living tissue, food, and water-soluble amino acids. Even a sample can be measured with high sensitivity without being affected by water absorption. In addition, uniform near-field light can be generated in the vicinity of the waveguide surface by the characteristic propagation mode of incident light, and measurement with high sensitivity and high accuracy is possible. The tubular waveguide refers to a dense cylindrical shape inside rather than a cavity, and the cross-sectional shape thereof may be a circle, an ellipse, a rectangle, a polygon, or the like.
[0010]
A terahertz wave or millimeter wave light source includes, for example, a backward wave tube, a terahertz wave parametric light source, a gun oscillator, an in-pad oscillator, a tannet oscillator, a photoconductive switch excitation by an ultrashort pulse laser, a quantum cascade laser, a p-Ge laser, It consists of a free electron laser. Waveguides, such as silicon single crystals, Teflon (registered trademark), plastic materials, quartz glass, ceramics, metal oxides, and semiconductors, have a small absorption coefficient in the terahertz wave or millimeter wave band, and have a refractive index that is higher than that of the sample to be measured. It is preferable that it is comprised with a high thing.
[0011]
In general, terahertz waves are electromagnetic waves having a frequency of 0.1 to 10 THz and a wavelength of 30 μm to 3 mm. The millimeter wave is an electromagnetic wave having a frequency of 30 to 300 GHz and a wavelength of 1 to 10 mm.
[0012]
In the near-field light measurement method according to the present invention, it is preferable to obtain information on the sample by detecting transmitted light that has passed through the waveguide. In this case, information on the sample can be obtained by measuring the intensity or intensity change of the transmitted light.
[0013]
[0014]
In the near-field light measurement method according to the present invention, the sample may be made of a liquid, powder, solid, gel substance, or gas, and information on the sample may be continuously measured. In this case, try

[0004]
It is possible to obtain temporal and spatial changes in fee information.
[0015]
The near-field light measurement method according to the present invention may be capable of spectroscopic measurement by changing the wavelength of the incident light or by dispersing the transmitted light with respect to the broadband incident light. In this case, the chemical substance contained in the sample and the structure of the substance can be specified.
[0016]
The near-field light measurement method according to the present invention may be capable of measuring the shape of the sample from a change in intensity of the transmitted light by changing a relative position between the sample and the waveguide. In this case, a two-dimensional image of the sample can be obtained from the measured shape of the sample. Further, as a method of changing the relative position between the sample and the waveguide, for example, a method of scanning by moving the sample along the waveguide, moving the waveguide along the surface of the sample, There is a method of moving the waveguide close to or away from each other. By combining these, not only the two-dimensional shape of the sample but also a three-dimensional shape can be obtained, and a three-dimensional image of the sample can also be obtained.
[0017]
In the near-field light measurement method according to the present invention, the waveguide may have a curvature along the propagation direction of the incident light. In this case, the shape of the waveguide can be matched to the shape of the sample and the measurement situation, and efficient measurement can be performed. In addition, since the interaction area between the sample and the near-field light can be expanded, highly sensitive measurement is possible. The curvature of the waveguide is preferably in a range where the characteristic propagation mode of incident light does not change.
[0018]
The near-field light measuring device according to the present invention has a terahertz wave or millimeter wave light source, a terahertz wave or millimeter wave band with a small absorption coefficient, a refractive index higher than that of the sample to be measured, a tubular shape, A waveguide having an inner diameter of 6 to 1000 times the wavelength of the incident light of the terahertz wave or millimeter wave, the waveguide provided so as to be able to propagate the incident light, and the characteristic propagation mode of the incident light, And a detection unit that detects transmitted light that has passed through the waveguide so as to acquire information on the sample disposed within the reach of near-field light generated in the vicinity of the surface.
[0019]
The near-field light measurement apparatus according to the present invention is used to implement the near-field light measurement method according to the present invention. The near-field light measurement apparatus according to the present invention uses the near-field light of terahertz waves or millimeter waves to obtain information on the sample arranged within the reach of the near-field light.

Claims (9)

  Terahertz wave or millimeter wave incident light generated by a terahertz wave or millimeter wave light source is propagated to the waveguide, and is placed within the reach of the near field light by the near field light generated outside the waveguide. A near-field optical measurement method characterized by obtaining information on a sample obtained. Obtaining information about the sample by detecting transmitted light that has passed through the waveguide;
The near-field light measurement method according to claim 1, wherein: The waveguide is tubular and has an inner diameter of 6 to 1000 times the wavelength of the incident light,
The near-field light is generated near the surface of the waveguide due to a characteristic propagation mode of the incident light.
The near-field light measurement method according to claim 1 or 2, characterized in that: The sample consists of a liquid, powder, solid, gel substance or gas,
The information of the sample can be continuously measured,
The near-field light measurement method according to claim 1, 2, or 3.   The near-field light according to claim 2, 3 or 4, wherein the near-field light can be spectroscopically measured by changing a wavelength of the incident light or by dispersing the transmitted light with respect to the incident light having a wide band. Measurement method.   6. The proximity according to claim 2, wherein the shape of the sample can be measured from a change in intensity of the transmitted light by changing a relative position between the sample and the waveguide. Field light measurement method.   The near-field light measurement method according to claim 1, wherein the waveguide has a curvature along a propagation direction of the incident light. A terahertz or millimeter wave light source,
A waveguide provided to be able to propagate terahertz wave or millimeter wave incident light from the light source;
A detection unit that detects transmitted light that has passed through the waveguide so as to acquire information on a sample disposed within the reach of near-field light generated outside the waveguide;
A near-field light measuring device comprising: Moving means provided to be able to move the sample or the waveguide so as to change the relative position between the sample and the waveguide within the reach of the near-field light;
When the transmitted light is detected by the detector while the sample or the waveguide is moved by the moving means, the shape of the sample is measured from the change in the intensity of the transmitted light to obtain a two-dimensional image or a three-dimensional image. Analyzing means to display with images,
9. The near-field light measuring device according to claim 8, further comprising:

Images