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WO2009084712A1 - Appareil et procédé d'acquisition d'informations de forme d'onde - Google Patents

Appareil et procédé d'acquisition d'informations de forme d'onde Download PDF

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Publication number
WO2009084712A1
WO2009084712A1 PCT/JP2008/073925 JP2008073925W WO2009084712A1 WO 2009084712 A1 WO2009084712 A1 WO 2009084712A1 JP 2008073925 W JP2008073925 W JP 2008073925W WO 2009084712 A1 WO2009084712 A1 WO 2009084712A1
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WIPO (PCT)
Prior art keywords
terahertz wave
propagation
waveform
delay
waveform information
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/JP2008/073925
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English (en)
Inventor
Takeaki Itsuji
Shintaro Kasai
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Canon Inc
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Canon Inc
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Filing date
Publication date
Priority claimed from JP2008287755A external-priority patent/JP4975001B2/ja
Application filed by Canon Inc filed Critical Canon Inc
Priority to US12/680,889 priority Critical patent/US8129683B2/en
Publication of WO2009084712A1 publication Critical patent/WO2009084712A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
    • G01N21/3586—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation by Terahertz time domain spectroscopy [THz-TDS]

Definitions

  • the THz-TDS is a measurement method for acquiring a temporal waveform of the terahertz wave (waveform of the terahertz wave represented with a time axis being taken as abscissa) which is transmitted through or reflected by a sample.
  • a technology for acquiring physical properties of the sample by using information regarding an amplitude and a phase of the waveform acquired by this method is disclosed in Japanese Patent Application Laid-Open No. 2005-274496.
  • the Terahertz time domain spectroscopy is carried out by using the ultrashort pulse having a time width smaller than that of the terahertz wave, Specifically, a pulse laser having a pulse width of several tens of femtoseconds is used as the ultrashort pulse for sampling an amplitude (such as a photocurrent value) at a certain time on the temporal waveform of the terahertz wave. Then, the timing of irradiating light to the position at which the terahertz wave is emitted or detected is changed. As a result, the amplitude (such as the photocurrent value) of the terahertz wave can be acquired while the position on the temporal waveform at which each sampling is performed is being changed. As a result, the whole temporal waveform can be reproduced.
  • a pulse laser having a pulse width of several tens of femtoseconds is used as the ultrashort pulse for sampling an amplitude (such as a photocurrent value) at a certain time
  • a movable mirror for changing an optical path length of the ultrashort pulse is used as an optical delay system.
  • an object of the present invention to provide an apparatus and a method which are capable of acquiring information regarding a temporal waveform by a technique different from that described above using an optical delay system. It should be understood that the present invention does not exclude the combination of the above-mentioned conventional technique using the optical delay system and the novel technique.
  • a terahertz time domain spectroscopy method including: generating a terahertz wave; allowing the generated terahertz wave to propagate; detecting information regarding the propagating terahertz wave; and constructing a temporal waveform of the terahertz wave from the detected information regarding the terahertz wave, wherein a propagation velocity of the terahertz wave is changed to acquire the temporal waveform.
  • the propagation velocity (effective propagation distance) of the terahertz wave propagating through the propagation portion can be controlled.
  • a propagation time of the terahertz wave can be controlled.
  • a temporal waveform of a terahertz wave can be acquired.
  • FIGS. IA, IB and 1C are schematic views for illustrating a waveform information acquisition apparatus in accordance with a first embodiment.
  • FIG. 2 is a schematic view for illustrating a waveform information acquisition apparatus in accordance with a second embodiment.
  • FIG. 3 is a schematic view for illustrating a waveform information acquisition apparatus in accordance with one mode of the second embodiment.
  • FIG. 5 is a graphical representation for illustrating a temporal waveform of the terahertz wave constructed in an arithmetic processing unit.
  • FIG. 7 is a schematic view for illustrating a waveform information acquisition apparatus in accordance with Example 1.
  • FIGS. 9A, 9B and 9C are graphical representations showing results of analysis of the waveform information of the terahertz wave in Example 1.
  • FIG. 10 is a schematic perspective view for illustrating a waveform information acquisition apparatus in accordance with Example 2.
  • FIGS. HA and HB are schematic views for illustrating Example 3.
  • FIG. 14 is a schematic view for illustrating still another example.
  • FIGS. 15A, 15B and 15C are schematic views for illustrating a change in optical path length of the terahertz wave in Example 4.
  • a generation portion 101 generates the terahertz wave.
  • the generation portion 101 for example, there is included a generation portion which includes a carrier generation layer and uses the above-mentioned photoconductive film for generating the terahertz wave by application of an electric field to the carriers.
  • a resonance tunnel diode having a structure, in which the electric field (or voltage) is applied to cause a resonance tunnel phenomenon, or the like can be used.
  • the generation portion used in the present invention is not limited to those described above.
  • a voltage applied to liquid crystal can be changed in order to change the orientation of liquid crystal molecules.
  • the liquid crystal molecules each having the refractive index in a longitudinal direction different from that in a horizontal direction, are used, the refractive index perceived by the terahertz wave is changed by adjusting the orientation of the liquid crystal molecules with respect to the deflection of the terahertz wave propagating through the propagation portion 102.
  • the propagation velocity of the terahertz wave is changed.
  • the propagation velocity (effective propagation distance) of the terahertz wave can also be changed by changing a concentration of a gas surrounding the region through which the terahertz wave propagates .
  • the amount of change (for example, optical path length of a trigger signal output to the detection portion 303) of the second delay portion 309 from a certain reference value (0 second when converted into time) is converted into time.
  • the position (amount of delay) of the second delay portion 309 is adjusted so as to achieve a predetermined observation time to thereby adjust the time at which the trigger signal reaches the detection portion 303.
  • the instantaneous value of the terahertz wave (electric field intensity of the terahertz wave) at the predetermined observation time is detected by the detection portion 303.
  • the trigger signal is not limited to the light irradiation to the generation portion 301 and the detection portion 303.
  • an electric field or voltage
  • the distribution state of the refractive index of the propagation portion 302 is adjusted by the distance between the first delay portion 304 and the propagation portion 302, the adjustment of the distribution state of the refractive index of the propagation portion 302 is not limited thereto.
  • the first delay portion 304 may be constituted of a member which is capable of changing the refractive index by using the electrical means, such as a liquid crystal and an electrode for using the electrical means.
  • the delay adjustment portion 305 functions as a control portion for changing the refractive index of the first delay portion 304 by using the electrical means.
  • the temporal waveform 401 is acquired as follows. Specifically, in a state where the distance between the first delay portion 304 and the propagation portion 302 is fixed to a certain distance xl, the trigger signal is swept (delayed in time) in the second delay portion 309. Similarly, the temporal waveform 402 is a temporal waveform of the terahertz wave acquired in a state where the distance is x2.
  • the propagation velocity (effective propagation distance) of the terahertz wave is changed to acquire the temporal waveform of the terahertz wave. In this manner, the time period until the terahertz wave reaches the detection portion 303 is changed. Then, during the observation time (or at the observation position) predetermined by the second delay portion 309, a signal changing with the change in propagation velocity
  • the shape of the temporal waveform of the terahertz wave is distorted. Specifically, the intensity and pulse width of the terahertz wave change.
  • the shape of the temporal waveform of the terahertz wave is influenced by the characteristics of the loss and the characteristics of the dispersion of the means for generating a change in refractive index of the terahertz wave.
  • a correction value for correcting the distortion of the shape is stored in a correction portion 306. By using the correction value, the temporal waveform taken before the shape of the temporal waveform is distorted is reconstructed from the temporal waveform constructed in the arithmetic processing portion 307.
  • the correction value for correcting the intensity and the phase for each frequency is stored for a predetermined observation position.
  • FIG. 6 shows an example of a table for correction, which is stored in the correction portion 306.
  • Frequency information before the correction which is illustrated in FIG. 6, corresponds to the temporal waveform
  • Example 1 Adjustment of Distance between First Delay Portion and Propagation Portion
  • FIG. 7 is a schematic view for illustrating the waveform information acquisition apparatus of Example 1.
  • a microstrip line including a first electrode 710, a dielectric 711, and a reference electrode 712 is used.
  • the propagation portion is formed on a silicon (Si) substrate (not illustrated) .
  • the dielectric 711 benzocyclobutene (BCB) is used.
  • the material of the dielectric 711 is not limited thereto, and a resin material such as a polyethylene or polyolefin material can be used. A material having a small loss with respect to the terahertz wave is desirable.
  • a semiconductor material such as semi-insulating silicon (SI- Si) can be used.
  • SI- Si semi-insulating silicon
  • the same material as that of a carrier generation layer can also be used.
  • the film thickness of the dielectric 711 is 3 ⁇ m.
  • a laser portion 708 is used as the trigger portion.
  • the generation portion configured including a first carrier generation layer 717 is irradiated with a laser light to be driven.
  • the detection portion configured including a second carrier generation layer 718 is also irradiated with a laser light to be driven.
  • the laser light irradiated to the first carrier generation layer 717 is referred to as pump light
  • the laser light irradiated to the second carrier generation layer 718 is referred to as probe light.
  • a titanium sapphire laser having a pulse width of 50 femtoseconds, a center wavelength of 800 nm, and a repetition frequency of 76 MHz is used.
  • the laser light output from the laser portion 708 is split by a beam splitter. Furthermore, through a mirror and a second delay portion 709, the laser lights are irradiated to the first carrier generation layer 717 and the second carrier generation layer 718.
  • the second delay portion 709 an optical delay system which includes the combination of a retroreflector and a return optical system and changes the optical path length of an ultrashort pulse with an actuator is employed.
  • the generation portion is constituted by the first carrier generation layer 717, the first electrode 710, the second electrode 715, and a bias application portion 719.
  • low-temperatur grown gallium arsenide (LT-GaAs) is used for the first carrier generation layer 717.
  • LT-GaAs is fabricated by molecular beam low-temperature epitaxial growth (at 250 0 C) and is peeled off from the Si-GaAs substrate for use.
  • the thickness of the first carrier generation layer 717 is 2 ⁇ m.
  • the second electrode 715 is a conductor obtained, for example, by stacking a layer of Ti with a thickness of 500 A and a layer of Au with a thickness of 3,000 A, as is the case with the first electrode 710.
  • the line width of the second electrode 715 is 10 ⁇ m.
  • the first electrode 710 and the second electrode 715 are provided on the first carrier generation layer 717 with a certain gap therebetween.
  • the gap is 5 ⁇ m.
  • the bias application portion 719 is a portion for applying a bias to the gap, and applies a bias at 10 V to the gap.
  • the pump light output from the laser portion 708 is irradiated to the gap to generate carriers.
  • the bias is applied to the carriers by the bias application portion 719 to accelerate the carriers.
  • an electromagnetic wave is generated and used as a terahertz wave.
  • the terahertz wave is coupled to the first electrode 710, and propagates through the propagation portion.
  • the structure of the detection portion is the same as that of the generation portion.
  • the detection portion is constituted by the second carrier generation layer 718, the first electrode 710, a third electrode 716, and a current- voltage conversion portion 723.
  • the second carrier generation layer 718 and the third electrode 716 have the same structures as those of the first carrier generation layer 717 and the second electrode 715 of the generation portion, respectively.
  • the current-voltage conversion portion 723 converts a current flowing through the third electrode 716 into a voltage, and then amplifies the voltage.
  • the probe light output from the laser portion 708 is irradiated to a gap between the first electrode 710 and the third electrode 716.
  • the gap is the same as that in the generation portion, and therefore, is 5 ⁇ m.
  • the probe light causes the carriers to be generated in the gap from the second carrier generation layer 718.
  • the generated carriers are fluctuated by an electromagnetic field of the terahertz wave propagating from the propagation portion.
  • a current signal involved in the fluctuation of the carriers is transmitted to the third electrode 716.
  • the current- voltage conversion portion 723 detects the current signal.
  • the detected signal is an instantaneous value at the observation position tn which is determined by the second delay portion 709.
  • the first delay portion 704 is constituted of a resin member 713 and an actuator 714.
  • the resin member 713 polyethylene is used.
  • the resin member 713 has a length of 500 ⁇ m in the longitudinal direction of the first electrode 710, a width of 100 ⁇ m, and a height of 500 ⁇ m.
  • the resin member 713 is located above the element in the vertical direction, with the first electrode 710 being taken as a center. Then, by changing the distance between the resin member 713 and the first electrode 710, the refractive index distribution of the propagation portion is changed to thereby adjust the effective propagation distance
  • FIG. 8 shows the result of analysis of the waveform of the terahertz wave reaching the second carrier generation layer 718 when the resin member 713 is brought close to the first electrode 710, in the present example.
  • a case where the waveform information acquisition apparatus in accordance with the present example is used for inspection of a sample is described with reference to FIG. 7.
  • a sample 720 is disposed on the first electrode
  • the terahertz wave detection apparatus in accordance with the present example uses the transmission line delay device as means for sweeping the ultrashort pulse when the temporal waveform of the terahertz wave is to be constructed. Therefore, in comparison with the conventional sweeping means using an optical delay system, the structure can be reduced in size to improve the control speed. In particular, in a device configuration for performing integration processing in order to improve the detection sensitivity for a terahertz wave, since the speed of sweeping the ultrashort pulse is high, a higher detection operation speed can be expected. Moreover, by suppressing the influence of the transmission line delay device on the terahertz wave by using the correction portion, a more practical apparatus can be provided.
  • the inspection can be performed at a higher speed.
  • the sample involves a change over time (for example, change in water content)
  • an inspection can be performed while suppressing the influence of the change over time.
  • FIGS. 9A, 9B and 9C A method of controlling the first delay portion 704 and the second delay portion 709 when the temporal waveform of the terahertz wave is to be acquired is described with reference to FIGS. 9A, 9B and 9C.
  • a plurality of observation positions tl, t2 and t3 are determined in FIGS. 9A, 9B and 9C by the second delay portion 709. For each of the observation positions tl to t3, the time period in which the terahertz wave reaches the second carrier generation layer 718 is adjusted by the first delay portion 704.
  • the second delay portion 709 sequentially selects the plurality of observation positions tl, t2 and t3.
  • the first delay portion 704 adjusts the time period in which the terahertz wave reaches the second carrier generation layer 718 for each observation position and the temporal waveform of the terahertz wave is constructed in the arithmetic processing portion.
  • the first delay portion 704 is constituted of the resin material 713 and the actuator 714 and can adjust the time period in which the terahertz wave reaches the second carrier generation layer 718 within the range of 1 picosecond.
  • the observation position of the second delay portion 709 is adjusted to 1 picosecond (tl of FIG. 9A) .
  • the first delay portion 704 adjusts the distance from the first electrode 710, and the arithmetic processing portion acquires the temporal waveform of the terahertz wave from 0 picoseconds to the observation position tl.
  • the second delay portion 709 adjusts the observation position to 2 picoseconds (t2 of FIG. 9B) .
  • the first delay portion 704 adjusts the distance from the first electrode 710 again, and the arithmetic processing portion acquires the temporal waveform of the terahertz wave from tl to t2. Further, for an observation position at 3 picoseconds (t3 of FIG.
  • the terahertz wave detection apparatus performs the same operation. Such an operation is sequentially performed for a plurality of preset observation positions to acquire the temporal waveform of the terahertz wave.
  • the temporal waveform of the terahertz wave which is acquired in the arithmetic processing portion
  • the temporal waveform corresponding to the amount of adjustment is acquired by the first delay portion 704 from the observation position as a start point (0 seconds) (see waveform (A) of FIG. 5) . Therefore, the start point is the same for the temporal waveform at each observation position. Therefore, the arithmetic processing portion refers to the respective observation positions to construct the continuous temporal waveform of the terahertz wave.
  • the table for correction which corresponds to the combination of the observation positions, is prepared in advance.
  • the arithmetic processing portion selects the table for correction from the correction portion based on the combination of the observation positions, which is used for the construction of the temporal waveform of the terahertz wave, to suppress the influence of the transmission line delay device on the terahertz wave.
  • the arithmetic processing portion uses the correction values in the table to reconstruct the acquired temporal waveform of the terahertz wave.
  • the terahertz wave detection apparatus in accordance with the present example and the inspection apparatus using the terahertz wave detection apparatus can acquire the temporal waveform of the terahertz wave for a long period of time even if the amount of adjustment of the transmission line delay device is small.
  • Example 2 Change in Refractive Index Caused by Using Electrical Means
  • FIG. 10 is a configuration diagram for illustrating the waveform information acquisition apparatus in accordance with the present example.
  • the present example is one mode of the terahertz wave detection apparatus in accordance with the present invention. Specifically, a variation of the above-mentioned transmission line delay device is described.
  • the refractive index distribution of the propagation portion is mechanically adjusted by using the first delay portion.
  • the present example differs from the other examples in that the refractive index distribution of the propagation portion is electrically adjusted.
  • a liquid crystal member 1013 is used as the first delay portion.
  • the liquid crystal member 1013 methoxybenzylidene aniline (MBBA) is used.
  • the liquid crystal member 1013 is constituted of MBBA, a cell containing the MBBA, and electrodes for adjusting the orientation of liquid crystal molecules.
  • the liquid crystal member 1013 is provided in contact with a first electrode 1010.
  • a delay adjustment portion 1005 is a control portion for adjusting the orientation of the liquid crystal molecules of the liquid crystal member 1013 through the electrodes constituting the liquid crystal member 1013. By adjusting the orientation of liquid crystal molecules of the liquid crystal member 1013, the refractive index can be adjusted.
  • Other liquid crystal materials can be used as the material of the liquid crystal member 1013.
  • the material of the first delay portion is not limited to the liquid crystal material, and may be any material as long as the refractive index can be electrically changed.
  • a mode of adjusting the dispersion of colloids in a colloidal solution can also be employed.
  • Example 2 the means for electrically adjusting the refractive index distribution of the propagation portion is not in contact with the first electrode 1010. Furthermore, in another variation of Example 2, there may be employed a configuration in which the distance between the means for electrically adjusting the refractive index distribution of the propagation portion and the first electrode 1010 is made variable.
  • Example 3 is described with reference to FIGS. HA and HB.
  • FIGS. HA and HB are schematic views for illustrating a waveform information acquisition apparatus including a coupling portion for coupling a terahertz wave to a propagation portion.
  • the present example is one mode related to the terahertz wave detection device in accordance with the present invention. Specifically, a variation of the transmission line delay device described above and an apparatus using the transmission line delay device is described.
  • the generation portion and the detection portion are integratedly formed in the transmission line delay device, these elements are separated from each other in the present example.
  • FIG. HA is a schematic configuration diagram of the transmission line delay device in accordance with the present example.
  • a coupling portion 1122 is connected to a propagation portion 1102.
  • a first delay portion 1104 constituted of a resin member 1113 and an actuator 1114 is provided above the propagation portion 1102 in the vertical direction.
  • the refractive index distribution of the propagation portion 1102 can be adjusted by the first delay portion 1104.
  • the configuration described for Example 1 is used as the first delay portion 1104, the configurations described in the other examples can also be used.
  • the coupling portion 1122 couples the terahertz wave propagating through the space to the transmission line delay device.
  • the coupling portion 1122 also couples the terahertz wave propagating through the transmission line delay device with the space.
  • FIG. HB shows an example of a system configuration diagram when such a transmission line delay device is applied to a terahertz wave detection apparatus.
  • a photoconductive element 1801 is used as a generation portion for generating a terahertz wave by a pump light irradiated from a laser portion 1108.
  • a photoconductive element 1803 is used as a detection portion.
  • the photoconductive element 1801 is an element having an antenna pattern formed on a semiconductor thin film.
  • an SI-GaAs substrate having LT-GaAs grown on a surface thereof is used as the semiconductor thin film. Then, a dipole antenna (antenna length: 30 ⁇ m; conductor width: 10 ⁇ m) made of a conductor obtained by stacking a Ti layer with a thickness of 500 A and an Au layer with a thickness of 3,000 A and having a gap of 5 ⁇ m at a center thereof is formed on the LT-GaAs. Moreover, as with Example 1 described above, a bias application portion 1119 for applying a bias to the gap is provided.
  • the pump light is irradiated to the gap while applying a bias of 10 V to the gap by the bias application portion 1119.
  • a pulsed terahertz wave having a half width value of about 200 femtoseconds is generated.
  • the shape of the antenna is not limited to that described above.
  • a bow-tie antenna or a spiral antenna which is common as a wideband antenna, may also be used.
  • the semiconductor thin film is not limited to that described above, and a semiconductor material such as InGaAs may also be used.
  • the generation portion is not limited to the photoconductive element 1801.
  • a semiconductor material itself may be used as the generation portion.
  • the pump light is irradiated on a mirror-polished surface of GaAs, and by a change over time in instantaneous current generated at this time, a terahertz wave is generated.
  • organic crystal such as 4-dimethylamino-n-methyl-4-stilbazolium Tosylate (DAST) crystal may be used.
  • the photoconductive element 1803 detects the terahertz wave with a probe light irradiated from the laser portion 1108.
  • the photoconductive element 1803 is an element including an antenna pattern formed on a semiconductor thin film.
  • the photoconductive element 1803 includes a current-voltage conversion portion (not shown) for detecting the instantaneous current in accordance with the intensity of the electric field of the terahertz wave.
  • the configuration of the detection portion is not limited to the photoconductive element 1803.
  • a heat detector such as a bolometer or a pyroelectric detection element such as Deuterated L-Alanine Triglycine Sulphate (DLATGS) can also be used as the detection portion.
  • DLATGS Deuterated L-Alanine Triglycine Sulphate
  • the configuration of the laser portion 1108 is appropriately selected depending on a target of irradiation such as described for Example 1.
  • the configuration allows a terahertz wave to be coupled to the transmission line delay device by using the coupling portion.
  • the terahertz wave detection apparatus of the present example and the inspection apparatus using the terahertz wave detection apparatus can improve the degree of freedom in device design.
  • any one of the generation portion and the detection portion is integrated with the transmission line delay device to allow coupling to the outside through a coupling portion.
  • FIG. 12A is a schematic configuration diagram of a transmission line delay device in accordance with the variation of Example 3.
  • the generation portion described above is integrated with the propagation portion.
  • a coupling portion 1222 is connected to a first electrode 1210.
  • the coupling portion 1222 has a spherical antenna configuration including a reference electrode 1212 as an earth conductor.
  • the coupling portion 1222 is a silicon sphere having a diameter of 100 ⁇ m and coated with Au.
  • the first electrode 1210 and the coupling portion 1222 are fixed by thermocompression bonding.
  • the antenna configuration of the present variation 3 is a wideband antenna having a sensitivity in the vicinity of about 1 THz, Moreover, as described for the example above, the structure of the coupling portion 1222 is not limited thereto.
  • FIG. 12B shows an example of a system configuration diagram when the transmission line delay device is applied to a terahertz wave detection apparatus.
  • a terahertz wave generated from the transmission line delay device integrated with the generation portion is detected by a photoconductive element 1203 provided in the space.
  • the configuration, in which the generation portion is integrated with the transmission line delay device, is described in the present variation, but a configuration, in which the detection portion is integrated with the transmission line delay device, can also be used.
  • the photoconductive element 1203 is used as the detection portion in the present variation, but other modes are also applicable as described for Example 3 above.
  • the terahertz wave detection apparatus in accordance with the present variation and the inspection apparatus using the terahertz wave detection apparatus have the structure in which the generation portion or the detection portion is integrated with the transmission line delay device, and hence the number of elements to be optically adjusted is reduced to facilitate the handling. (Other Examples)
  • the mode of adjusting the refractive index distribution of the propagation portion may have configurations such as illustrated in FIGS. 13 and 14, depending on the structures of the dielectric and the reference electrode.
  • a propagation portion 1302 is a microstrip line type propagation portion.
  • a first delay portion 1304 is inserted into a part of a dielectric 1311.
  • a propagation portion 1402 is a strip line type propagation portion.
  • the refractive index distribution is adjusted by the arrangement relation between a reference electrode 1412 and a first delay portion 1404.
  • the positional relation of the first delay portion is not limited as long as the first delay portion can adjust the distribution of the electromagnetic field of the terahertz wave propagating through the propagation portion.
  • the terahertz wave detection device obtained by appropriately combining the structures and the spirits described in the examples above is provided. Other device structures are not excluded without departing from the sprit of the present invention. (Example 4: Prism)
  • Example 4 is described with reference to FIGS. 15A, 15B and 15C.
  • a generation-side photoconductive antenna element 1802 for generating a terahertz wave includes a dipole antenna (not shown) formed on LT-GaAs. Pump light 1801 is irradiated to a predetermined position of the dipole antenna of the generation-side photoconductive antenna element 1802 to generate a terahertz wave.
  • the terahertz wave generated from the generation-side photoconductive antenna element 1802 is collimated by a parabolic mirror
  • Probe light 1807 is incident simultaneously with the incidence of the terahertz wave on the detection-side photoconductive antenna element 1806. As a result, the terahertz wave is detected.
  • a pair of dielectric (for example, polyethylene) prisms 1804a, 1804b is inserted into a path of the terahertz wave.
  • Each of the pair of prisms 1804a, 1804b has a surface perpendicular to the optical axis and a surface inclined with respect to the optical axis as illustrated in FIG. 15A. It is preferred that the inclined surfaces of the pair of prisms 1804a, 1804b be parallel to each other. The parallel surfaces are depicted as being apart from each other in FIG. 15A, but the parallel surfaces may be in close contact with each other.
  • the pair of prisms 1804a and 1804b serves as a parallel dielectric plate with respect to the terahertz wave. When the pair of prisms 1804a, 1804b is moved in a direction indicated by an arrow in FIG. 15A, the substantial thickness of the dielectric plates with respect to the terahertz wave is changed (increased) .
  • the increase in the substantial thickness of the pair of prisms 1804a, 1804b with respect to the terahertz wave increases an optical path length of the terahertz wave.
  • the timing at which the terahertz wave reaches the detection-side photoconductive antenna element 1806 and the timing at which the probe light 1807 reaches the detection-side photoconductive antenna element 1806 are offset with respect to each other.
  • the temporal waveform of the terahertz wave can be obtained.
  • a pair of polyethylene prisms each having an apex angle of 15° and a length of a surface perpendicular to the terahertz wave traveling direction of 100 mm is used.
  • the terahertz wave is transmitted through the pair of prisms as a collimated beam having a diameter of 50 mm.
  • the pair of prisms behaves as a parallel flat polyethylene plate having a thickness of 13.4 mm for the terahertz wave.
  • the pair of prisms behaves as a parallel flat polyethylene plate having a thickness of 26.8 mm for the terahertz wave.
  • the refractive index of polyethylene with respect to the terahertz wave is about 1.5
  • a change in optical path length of about 20 mm is obtained.
  • This value corresponds to a time delay of about 66 picoseconds in time.
  • the temporal waveform of the terahertz wave can be acquired in a time domain of 66 picoseconds.

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Abstract

L'invention porte sur un appareil et sur un procédé qui permettent l'acquisition d'une forme d'onde temporelle d'une onde térahertz se propageant, par changement d'une vitesse de propagation de l'onde térahertz. L'appareil d'acquisition d'informations de forme d'onde comprend une partie de génération pour générer une onde térahertz, une partie de propagation pour permettre à l'onde térahertz générée par la partie de propagation de se propager à travers celle-ci, une partie de détection pour détecter des informations de forme d'onde de l'onde térahertz, une première partie de retard pour changer une vitesse de propagation de l'onde térahertz, et une partie de commande pour commander la première partie de retard pour changer la vitesse de propagation de l'onde térahertz dans la partie de propagation, et acquiert des informations concernant la forme d'onde temporelle de l'onde térahertz détectée par la partie de détection.
PCT/JP2008/073925 2007-12-28 2008-12-25 Appareil et procédé d'acquisition d'informations de forme d'onde Ceased WO2009084712A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US12/680,889 US8129683B2 (en) 2007-12-28 2008-12-25 Waveform information acquisition apparatus and waveform information acquisition method

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2007340392 2007-12-28
JP2007-340392 2007-12-28
JP2008287755A JP4975001B2 (ja) 2007-12-28 2008-11-10 波形情報取得装置及び波形情報取得方法
JP2008-287755 2008-11-10

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WO2009084712A1 true WO2009084712A1 (fr) 2009-07-09

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WO (1) WO2009084712A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102696042A (zh) * 2010-01-08 2012-09-26 佳能株式会社 用于测量电磁波的装置和方法

Citations (2)

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Publication number Priority date Publication date Assignee Title
DE102006042642A1 (de) * 2006-09-12 2008-03-27 Batop Gmbh Terahertz Time-Domain Spektrometer
US20080210873A1 (en) * 2006-11-15 2008-09-04 Canon Kabushiki Kaisha Analysis apparatus and analysis method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006042642A1 (de) * 2006-09-12 2008-03-27 Batop Gmbh Terahertz Time-Domain Spektrometer
US20080210873A1 (en) * 2006-11-15 2008-09-04 Canon Kabushiki Kaisha Analysis apparatus and analysis method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NAGEL M ET AL: "THz biosensing devices: fundamentals and technology", JOURNAL OF PHYSICS: CONDENSED MATTER, INSTITUTE OF PHYSICS PUBLISHING, BRISTOL, GB, vol. 18, no. 18, 10 May 2006 (2006-05-10), pages S601 - S618, XP020101903, ISSN: 0953-8984 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102696042A (zh) * 2010-01-08 2012-09-26 佳能株式会社 用于测量电磁波的装置和方法
US9104912B2 (en) 2010-01-08 2015-08-11 Canon Kabushiki Kaisha Apparatus and method for measuring electromagnetic wave
CN102696042B (zh) * 2010-01-08 2015-11-25 佳能株式会社 用于测量电磁波的装置和方法

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