JP2007078381A - Light emitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitter having a continuous spectrum of high luminance, without pouring large amount of electric power into a narrow space. <P>SOLUTION: This light emitter comprises a rod-like or fibrous light emission member, comprising a material with a light-emitting point excited by absorption of light to spontaneously emit longer wavelength of light than that of the excitation light, and an excitation light source for irradiating the emission member with the light from an outside of the emitting member, and emits the light that propagates through the inside of the light-emitting member to the outside of the light-emitting member as an incoherent light from one end face of the light-emitting member, out of the lights emitted spontaneously from the light-emitting point of the light emitting member by the light irradiation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high intensity light emitter having a continuous spectrum.

  In order to realize a high-intensity point light source with a continuous spectrum in an incoherent (non-coherent) light source, a high-temperature part is formed by pouring high power into a narrow space so that a discharge lamp can be exemplified. However, the use of thermal radiation from the light emitting part is performed using the high temperature plasma at the high temperature part as the light emitting part. In this case, since the temperature of the light emitting part is high, the material adjacent to the light emitting part is required to have heat resistance, and the heat generated locally is released, so that a highly technical waste heat treatment means is required. Further, since it is a thermal light source, it does not emit radiation stronger than black body radiation at the temperature of the light emitting section, and once the light emitting section temperature is determined, the upper limit of the spectral radiance is determined. Here, spectral radiance refers to radiance per unit wavelength per unit solid angle.

  In addition, light generation technology using fluorescent materials is used in fluorescent lamps and cathode-ray tubes. However, if the energy for excitation is concentrated and the brightness is increased, the fluorescent material is heated due to the heat generated in the energy concentration section. There is a limit to increase the luminance of the light emitting part due to the burning of the light.

  On the other hand, a laser can produce high-quality parallel light, and a very high brightness can be obtained by focusing with a lens or the like. However, depending on applications such as spectroscopic measurement using a CCD, the coherence is obstructive and cannot be used. Further, the output light has a single wavelength, and a continuous spectrum cannot be realized. Although it is possible to change the wavelength over a certain range, it is difficult to emit light having a continuous spectrum.

  Patent Document 1 shows an example of an optical amplifier in which a laser medium is doped in a light emitting member. The laser medium uses a phenomenon in which an inversion distribution is created by excitation and stimulated emission is performed, and is distinguished from a spontaneously emitting fluorescent material. Although the laser medium can be used as a fluorescent material, in Patent Document 1, the laser medium does not function as a spontaneously emitting fluorescent material but functions as a stimulated emission medium. For this reason, although it becomes a coherent single wavelength amplifier, incoherent continuous spectrum light emission cannot be obtained.

  By the way, in recent years, an analysis method using a microchip called μ-TAS (μ-ToTal Analysis System), which applies micromachine technology and performs chemical analysis etc. by miniaturization as compared with a conventional apparatus, has attracted attention. ing. Patent Document 2 discloses this technique. Such an analysis system using a microchip performs all analysis processes such as mixing, reaction, separation, extraction, and detection of reagents in a fine flow path formed on a small substrate by micromachine fabrication technology. For example, it is used for analysis of blood in the medical field, analysis of biomolecules such as ultra trace amounts of proteins and nucleic acids, and the like.

  In μ-TAS, an optical measurement method such as an absorptiometry is often used to quantify extracted substances and reactive organisms. In the absorptiometry, a specimen is filled in a measurement cell having a very small cross section of about 10 to 100 μm square formed in a microchip, the measurement light is incident on the measurement cell, and the passing light that has passed through the measurement cell is measured. This is a method for detecting the component concentration by measuring the amount of light absorption of the liquid based on the received light and the passing light.

In the optical measurement of the μ-TAS absorptiometry, a light source having a high brightness with a continuous spectrum is required. A semiconductor laser or a light emitting diode has a narrow spectrum and is not suitable for absorption measurement. On the other hand, in the case of a high-intensity discharge lamp, the size of the light emitting part (light source size) is about several millimeters, which is too large for a light source used in a measurement cell of about 0.1 mm, and the light utilization rate does not increase. . However, at present, a high-intensity discharge lamp and an incandescent lamp are used because there is no appropriate light source even though the light utilization rate is very low. In other words, there is a demand for a light that has a continuous spectrum, provides light that is small and has high brightness, but there is nothing that satisfies this condition so far.
Japanese Patent Laid-Open No. 10-223961 JP 2004-109099 A

  Thus, due to the recent trend of micro-fabrication, there is an increasing demand for light having a continuous spectrum with high brightness, not limited to the field of μ-TAS described above.

  In addition, the high-intensity discharge lamp has a high temperature when the light emitting part is placed in a small space, so heat resistance is required for the material adjacent to the light emitting part, and locally generated heat is released. Waste heat treatment is required. As power increases, this waste heat is approaching its limit. For this reason, if high brightness can be obtained without pouring a large amount of power into a narrow space, this is a technically significant breakthrough.

  It is an object of the present invention to provide a light emitter having a continuous spectrum with high brightness without pouring high power into a narrow space.

  In order to solve the above problem, the invention according to claim 1 is a rod-like or fiber-like light emission made of a material having a light emitting point that is excited by light absorption and spontaneously emits light having a wavelength longer than that of the excitation light. A light source, and an excitation light source that irradiates the light emitting member with light from the outside of the light emitting member, and the light emission of light emitted spontaneously from the light emitting point in the light emitting member by the light irradiation. A light emitter is characterized in that light propagating through the inside of the member is emitted from the end face of the light emitting member as incoherent light to the outside of the light emitting member.

  The invention according to claim 2 is characterized in that the light source is a light source selected from a low-pressure mercury lamp, a rare gas excimer lamp, a xenon chloride (XeCl) excimer lamp, a fluorescent lamp, and a light emitting diode. The light emitter is as described.

  The invention according to claim 3 is characterized in that phosphor particles are dispersed as light emitting points in the light emitting member, and the size of the phosphor particles is smaller than the wavelength of the spontaneously emitted light. The light emitter according to Item 2.

  The invention according to claim 4 is the light emitter according to claim 2, wherein a straight tubular light source is used as the light source, and a fiber-like light emitting member is wound around the light source. .

  According to the first aspect of the present invention, it is possible to obtain a light emitter having a continuous spectrum with high luminance without pouring high power into a narrow space.

  According to the invention of claim 2, the low pressure mercury lamp, the rare gas fluorescent lamp, the excimer lamp, and the light emitting diode can be installed near the light emitting member because the temperature of the envelope is low, and the excitation light is efficiently emitted. Excitation efficiency is increased. Further, since the power density is low, the temperature rise of the light emitter can be small.

  According to the invention of claim 3, if the size of the fluorescent powder as the light emitting point existing in the light emitting member is smaller than the wavelength of the fluorescence emitted from the light emitting point, the fluorescence is difficult to be scattered. Attenuation of light toward the end face of the member can be reduced.

  According to the invention of claim 4, the use efficiency of the excitation light is increased and the light emitting member can be lengthened. Therefore, the efficiency of light coming out from the end face of the light emitting member can be increased and the strength can be increased.

  A light emitting point existing in the light emitting member is excited by excitation light, spontaneous emission occurs in the relaxation process, and light is emitted in a random direction. Of the emitted light, light emitted in a direction below the critical angle of the light emitting member can travel through the light emitting member by total reflection. In general, spontaneously emitted light has a wavelength longer than that of excitation light, and thus is not easily absorbed and reaches the end face without being greatly attenuated. The light emitted from the end of the light emitting member has a refractive index of the light emitting member that is high in the vicinity of the axis, and a light emitting member that has a low refractive index in the periphery, and the diameter of the core in the vicinity of the axis of the light emitting member is large The light source is approximately equivalent to the light source.

  When the transmittance of the light emitting member at the wavelength of light emission is high, since spontaneous emission is used, the intensity of light coming out from the end face increases in proportion to the length of the light emitting member, and high luminance is obtained. In the case of stimulated emission such as a laser, since it is non-linear, it is not proportional to the length of the light emitting member and depends on the intensity of the incident light. If the intensity is low, stimulated emission does not occur or the efficiency decreases. . In the case of stimulated emission, when excited with a weak power density, an inversion distribution cannot be obtained and stimulated emission does not occur.

  The upper limit of the light intensity is determined by the intensity that balances the light emission per unit length with the attenuation due to absorption and scattering, but the light emission member can reduce the absorption and scattering, so that brightness comparable to that of a high-intensity lamp can be obtained. In addition, since light emission is not thermal radiation, there is no limit of intensity due to black body radiation like high-intensity discharge lamps and halogen bulbs, and by suppressing absorption and scattering, it is possible to obtain intensity impossible with thermal light sources You can also.

  Since the light that travels through the light emitting member and emerges from the end face is a part of the emitted light (about 10%), the power efficiency of the light source remains low. However, in applications that require continuous-spectrum parallel light, such as spectral transmittance measurements, the light source brightness determines the light utilization efficiency of the system, so the light utilization efficiency is higher than using a low-intensity light source as it is. Is obtained.

  High-luminance light can be obtained from a low-luminance light source such as a low-pressure mercury lamp, rare gas fluorescent lamp, excimer lamp, or light-emitting diode. By increasing the luminance of the end face of the light emitter, the overall light utilization efficiency is increased. Further, since it is not necessary to increase the power density, a material having a low heat-resistant temperature can be used.

  FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. A rod-shaped light emitting member 1 is disposed adjacent to the excitation light source 10. Symbol 11 is an electrode. As the light emitting member 1, inorganic materials such as glass and ceramic, thermoplastic resins, thermosetting resins, elastomers, and other organic materials can be used. The light emitting point 2 can be a fluorescent substance or a point defect. A point defect refers to a defect generated in a crystal or glass by irradiating the crystal or glass solid with gamma rays, electron beams or particle beams. In the case of a light emitting member made of a transparent plastic to which a metal complex of a rare earth element or a transition metal element is added, the metal complex functions as a light emitting point.

Excitation light emitted from the excitation light source 10 is applied to the light emitting member 1 and acts on the light emitting point 2 of the light emitting member 1 to excite the light emitting point 2 to emit light. The emitted light reaches the peripheral surface of the light emitting member 1, propagates in the light emitting member 1 in the longitudinal direction, and is emitted from the end surface 1 a of the light emitting member 1.

  As shown in FIG. 1, when the light emitting member 1 is rod-shaped, the light from the excitation light source 10 is reflected to the light emitting member 1 side so that the excitation light from the excitation light source 10 is efficiently incident on the light emitting member 1. It is also effective to dispose the reflecting mirror 15 in the vicinity of the excitation light source 10 as indicated by a broken line in the drawing.

  FIG. 2 is another configuration diagram of the embodiment of the present invention. A fiber-shaped light emitting member 1 is wound around the excitation light source 10. In this case, it is only necessary to directly attach the light emitting member 1 to the excitation light source 10, and the structure is simple and compact. When the transmittance of the light emitting member 1 at the light emitting wavelength is high, the intensity of the light emitted from the end face 1a is increased substantially in proportion to the length of the light emitting member 1, and high luminance is obtained.

  Further, as shown in FIG. 3, when the substantially rod-shaped excitation light source 10 and the light emitting member 1 are arranged in the cylindrical reflecting mirror 16, the utilization rate of the excitation light is increased, and the light is emitted from the end face 1a of the light emitting member 1. The efficiency of incoming light can be increased.

Next, configuration examples of the excitation light source and the light emitting member will be described as specific examples of the present invention.
<Configuration example 1>
In the configuration of FIG. 2, the excitation light source 10 is a low-pressure mercury lamp having a total length of 60 mm and a diameter of 8 mm, and the light emitting member 1 is an inorganic solid silica glass fiber doped with cerium oxide and having a diameter of 0.1 mm and a length of 2000 mm. The silica glass fiber is wound around a low-pressure mercury lamp many times. The excitation wavelength is 254 nm, and the wavelength of the emitted light from the light emitting member 1 is in the range of 400 to 600 nm.

<Configuration example 2>
In the configuration of FIG. 2, the excitation light source 10 is a fluorescent lamp having a total length of 60 mm and a diameter of 3 mm, and the light emitting member 1 is a plastic which is an organic solid having a diameter of 0.2 mm and a length of 2000 mm obtained by adding an erbium complex to polymethylpentene. A fiber that is wound many times around a fluorescent lamp. The excitation wavelength is 400 to 600 nm, and the wavelength of the emitted light from the light emitting member 1 is near infrared light of 1.2 to 1.6 μm.

<Configuration example 3>
In the configuration of FIG. 2, the excitation light source 10 is a kind of xenon chloride excimer lamp having a total length of 60 mm and a diameter of 6 mm, and the light emitting member 1 is a plastic fiber that is an organic solid having a diameter of 0.5 mm and a length of 1000 mm. The plastic fiber is mixed with nano fluorescent particles having a particle size of 100 nm or less, such as MgWO ₄ , and is wound around the lamp many times. The excitation wavelength is 308 nm, and the wavelength of the emitted light from the light emitting member 1 is 360 to 700 nm.

<Other configurations>
In addition, as an example of the configuration of FIG. 1, a rod-shaped member made of silica glass, which is an inorganic solid doped with cerium oxide, ytterbium oxide or europium oxide, is used as the light emitting member 1, and an excitation light source A low-pressure mercury lamp or a rare gas excimer lamp may be used as 10 to emit a continuous spectrum in the visible region. Alternatively, as the light emitting member 1, a rod-shaped member made of phosphor nano-powder (Ca3 (PO4) 2: Tl +) mixed with alkali halide (KBr) fine powder and solidified at ultrahigh pressure to form a transparent body is used. As a low-pressure mercury lamp or a rare gas lamp, a visible spectrum can be emitted.

In the configuration example of FIG. 2, the light emitting member 1 is a light emitting member 1 in which a liquid is dispersed in a hydrophilic coating on phosphor nanopowder ((Sr, Ca) ₁₀ (PO ₄ ) 6 Cl: Eu ²⁺ ). A liquid (water) fiber can be used as the member, and a near-ultraviolet fluorescent lamp can be used as the excitation light source 10 to emit a continuous spectrum in the visible region. In addition, a liquid fiber in which a tube of an organic fluorescent dye (Rhodamine 6G: red) is filled as a light emitting member 1 and a fluorescent lamp of a near-ultraviolet phosphor is used as an excitation light source 10 to emit a red continuous spectrum. It can also be set as the structure to make.

  In addition, in the configuration example of FIG. 2, a fiber in which cerium, ytterbium, or europium complex is added as a fluorescent material to a plastic (polymethylpentene) that is an organic solid is used as the light emitting member 1. As a configuration, a fluorescent lamp made of a near-ultraviolet phosphor can be used to emit a continuous spectrum in the visible range. Furthermore, as the light emitting member 1, a fiber in which carbon nanotubes are added as a fluorescent material to an infrared transparent plastic which is an organic solid is used, and a light emitting diode is used as an excitation light source 10, and near infrared light (900 to 1100 nm) is used. It can also be set as the structure which discharge | releases. Further, as the light emitting member 1, an inorganic solid fiber in which silver (Ag) nanoparticles as a fluorescent material are dispersed in an alkali halide is used, a light emitting diode is used as the excitation light source 10, and near infrared light (900 (1100 nm) can also be emitted.

  FIG. 4 shows a configuration example in which the light emitter of the present invention is used in the μ-TAS apparatus. One structural example of the micro TAS chip 20 and the chip holder 25 is shown. The microchip 10 is made of a plastic material such as a thermoplastic resin such as PMMA (polymethyl methacrylate), PET (polyethylene terephthalate), PC (polycarbonate), or a thermosetting resin such as an epoxy resin. The microchip 20 shown in this example is formed by bonding two plate members. A groove is formed in advance on one side of the bonding surface, and a cavity in which the groove is continuous is formed by bonding. An analysis solution is introduced from the outside of the chip, reacted with a reagent to prepare a test solution, and the test solution is stored in the measurement cell 21 in the figure. Light is passed through the measurement cell 21 from the outside, the wavelength is selected by the filter 35, the light is received by the photodiode 30, and a predetermined component analysis is performed. Symbols 22 a and 22 b are apertures formed in the chip holder 25.

  FIG. 5 shows an example of a specific emission spectrum emitted from the light radiator having the configuration of FIG. The excitation light source 10 is a low-pressure mercury lamp, and the light emitting member is a silica glass fiber that is an inorganic solid doped with a cerium oxide. The silica glass fiber is wound around the low-pressure mercury lamp many times. The excitation wavelength is 254 nm, and the wavelength of the emitted light from the light emitting member 1 is in the range of 400 to 600 nm as shown in the figure.

Using a commercially available luminance meter, the luminance comparison between the conventional light source and the light emitter of the present invention was completed. The luminance meter was focused on the light emitting portion of each light source and measured. As a result, in the fluorescent lamp, the range is 10 ³ to 10 ⁵ cd / m ² , and in the xenon lamp, the range is 10 ⁸ to 10 ⁹ cd / m ² . The combination of the low-pressure mercury lamp and the silica glass fiber which is an inorganic solid doped with a cerium oxide was in the range of 10 ⁷ to 10 ⁹ cd / m ² . The light emitter of the present invention was confirmed to have a luminance equivalent to that of a xenon lamp.

  It is a fluorescent substance as a light emitting point existing in the light emitting member, and the fluorescent substance is titanate, zirconate, vanadate, tantalate, molybdate, tungstate, manganese, antimony , Halophosphates, phosphates with thallium, tin, lead, bismuth ions as activators, or oxides with dispersed rare earth ions such as cerium, ytterbium, europium, halophosphates, phosphates, chalcogenites, When the metal complex, organic fluorescent dye, or organic fluorescent pigment is used, the luminous efficiency of fluorescence with respect to excitation light can be increased, and high luminance can be obtained.

  By irradiating a crystal or glass solid with gamma rays, electron beams, or particle beams, point defects are generated in the crystal or glass. This defect behaves as a light emitting point. When a defect is introduced into a homogeneous material by irradiation, a homogeneous defect is formed, and since the point defect has a small light emitting point size, Rayleigh scattering is small and light output can be increased.

  If the light emitting member is a transparent plastic that is an organic solid to which a metal complex of a rare earth element or a transition metal element is added, the fluorescence scattered from the phosphor powder is reduced, so that the attenuation of light toward the end face of the light emitting member is reduced. Less. If there are two or more kinds of fluorescent substances present in the light emitting member, the light emission of a plurality of fluorescent substances is almost added except for the excitation band of each fluorescent substance, so that a desired emission spectrum may be obtained. it can.

  In the light emitting member where the refractive index of the light emitting member is high on the axis and low in the peripheral portion, the proportion of effective light that travels along the light emitting member decreases as the light emitting member from the phosphor emits light. When the concentration of the substance is high on the axis and low on the periphery, the effective light ratio increases, so that the amount of light emitted from the end face can be increased.

  By providing the light reflecting member on one end face of the light emitting member, the amount of light emitted from the other end face can be increased. A non-reflective coating is provided on the light emitting end face of the light emitting member. If it does so, the light quantity which comes out from an end surface can be increased by providing an antireflection means in one end surface of a light emission member.

  When the diameter of the light emitting member is 0.1 mm or more, the diffracted light from the end surface of the light emitting member becomes weak and difficult to interfere, so that the quality as an incoherent point light source is improved. Up to about 1 mm is practical.

  By forming a plurality of light emitting members and bundling them at the light extraction end, a desired shape can be irradiated. Moreover, the light emission member containing a different kind of fluorescent material can also be bundled.

  When a hollow double tube-shaped excitation light source is used and the light emission member is arranged outside the hollow part of the double tube, the light emission surface area of the excitation light source is increased, so that the contact area with the light emission member is increased and the use efficiency is increased. In addition, the light emitting member can be lengthened while increasing, so that the efficiency of light coming out from the end face of the light emitting member can be increased and the strength can be increased.

  When a light emitting member that emits short wavelength fluorescence is connected to a light emitting member that emits long wavelength fluorescence, and a light emitting member that emits short wavelength fluorescence is disposed on the side closer to the light extraction end, light that emits long wavelength fluorescence Since the emission member is not easily absorbed by the light emission member that emits short-wavelength fluorescence, high intensity can be obtained without lowering the light intensity at the light extraction end.

It is a schematic diagram which shows the principle of the light emitter of this invention. It is a schematic diagram which shows the basic composition of the light emitter of this invention. It is a schematic diagram which shows the other structure of the light emitter of this invention. As an application example of the light emitter of the present invention, a configuration example in which the light emitter of the present invention is used in a μTAS apparatus is shown. An example of the emission spectrum of the light emitter of the present invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission member 1a End surface 2 Light emission point 10 Excitation light source 11 Electrode 15 Reflection mirror 16 Reflection mirror 20 μ-TAS chip 21 Measurement cell 22a, 22b Aperture 25 Chip holder 30 Photodiode 35 Filter 100 Light emitter

Claims (4)

A rod-like or fiber-like light emitting member made of a material having a light emitting point that is excited by absorption of light and spontaneously emits light having a wavelength longer than that of the excitation light, and the light emitting member is irradiated with light from the outside of the light emitting member An excitation light source that
Of the light spontaneously emitted from the light emitting point in the light emitting member by the light irradiation, the light propagating through the light emitting member is converted into incoherent light from the end surface of the light emitting member. A light emitter characterized by being emitted to the outside.   The light emitter according to claim 1, wherein the excitation light source is a light source selected from a low-pressure mercury lamp, a rare gas excimer lamp, a xenon chloride excimer lamp, a fluorescent lamp, and a light emitting diode.   3. The light emitter according to claim 2, wherein phosphor particles are dispersed as the light emitting points in the light emitting member, and the size of the phosphor particles is smaller than the wavelength of the spontaneously emitted light. . The light emitter according to claim 2, wherein a straight tubular light source is used as the excitation light source, and a fiber-like light emitting member is wound around the light source.

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