JPH0713082A - Micropolarizing light source - Google Patents

Abstract

PURPOSE:To provide the micropolarizing light source applicable to polarization observation of a near visual field microscope and photon STM. CONSTITUTION:Al is deposited by evaporation on a pipette 1 of 0.9mum diameter in the aperture at its front end. A toluene soln. of polyether sulfone is packed into the front end of the pipette 1 and is solidified. 'Rhodamine 19' (produced by Ramda Physique) is deposited by evaporation as a quencher thereon to cover the surface of a high polymer 2 and the Al film. The quencher at the front end is removed and abrasion is induced on the surface of the high polymer 2 by irradiating the front end with an excimer laser. The photophor molecules expressed by formula are deposited by evaporation thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a minute polarized light source used in a near-field microscope, a photon scanning tunneling microscope (hereinafter referred to as a photon STM) or the like.

[0002]

2. Description of the Related Art Conventionally, an observation means such as a near-field microscope or a photon STM for performing optical observation is known in which a minute aperture having a diameter shorter than a wavelength is used in place of a lens in order to focus light. ing. In the near-field region that is short with respect to the wavelength, the evanescent wave leaking from the minute aperture spreads in a small manner, so that it is possible to observe a minute region that is not limited by the diffraction limit of light. Micro light sources used in these methods include (1) a sharp optical fiber coated with a metal, and a fine opening is formed by etching away the metal in the micro region at the tip end,
Alternatively, (2) as shown in FIG. 4, there is a pipette 17 extended to miniaturize the tip opening 18 and metal is vapor-deposited on the outer wall (Nature 237, 510, 1972). All of these emit light from the root through the portion of the tip opening that is not covered with metal.
Recently, as shown in FIG. 5, a light source has been developed in which a phosphor layer 20 is formed near the opening in a pipette 19 and emits fluorescence 22 by excitation light 21 from the outside (Molecular Crystal Liquid). Crystal 183, 383, 1990). This new lower excitation type phosphor light source is far superior to the above-mentioned light source of the type that transmits through the aperture, from the viewpoint of the obtained light intensity, durability and the like.

[0003]

By the way, even in a near-field microscope or a photon STM, much useful information such as molecular orientation can be obtained if observation by polarized light is possible like an ordinary optical microscope. Therefore, its significance is great.

However, in the near-field microscope and the Photon STM, there is no report on a minute polarized light source necessary for polarized light observation. In an ordinary optical microscope, polarized observation light is obtained by using a polarizer, but it cannot be obtained by a near-field microscope or Photon STM. This is for the following reasons. That is, in a near-field microscope or a Photon STM, the resolution sharply deteriorates as the distance between the light source and the sample surface increases, so observation is usually performed at a distance of several hundred angstroms or less. This is because a film-type or crystal-type polarizer to be used or a type of polarizer in which metal and quartz are alternately deposited is too large to be mounted on a light source or inserted between a light source and a sample.

In order to solve the above-mentioned problems of the prior art, it is an object of the present invention to provide a minute polarized light source which can be applied to the polarization observation of a near field microscope or a photon STM.

[0006]

In order to achieve the above object, the first structure of the micro-polarized light source according to the present invention is a micro-polarized light source having a tip with a diameter of 1 μm or less. Except the peripheral portion is coated with a metal, the surface of the tip portion is provided with a phosphor layer in which the phosphor molecules having optical anisotropy are uniaxially aligned, irradiated with excitation light from the outside, and polarized from the phosphor layer. It is characterized by emitting fluorescence.

In the first structure, the phosphor layer is formed on the outer wall of the minute polarized light source including the tip, and the quencher layer for quenching the fluorescence of the phosphor is provided around the tip. Is preferably formed on top of.

In the first structure, it is preferable that the phosphor molecule is a photochromic compound that forms an associate. Further, in the first configuration, the absorption layer is formed in contact with the phosphor layer, and energy is transferred from the absorption layer that has absorbed the excitation light so that polarized fluorescence is emitted from the phosphor layer. Is preferred.

A second configuration of the micro-polarized light source according to the present invention is a micro-polarized light source having a tip portion having a diameter of 1 μm or less, wherein the peripheral portion except the tip portion is covered with a metal, and the tip is provided. A phosphor layer is provided inside the part,
An absorption layer in which absorber molecules are uniaxially oriented is formed in the opening,
It is characterized in that excitation light is radiated from the outside to convert the fluorescence emitted from the phosphor layer into polarized fluorescence through the absorption layer.

[0010]

According to the first aspect of the present invention, the phosphor layer is formed by irradiating the phosphor layer formed at the tip with excitation light from a light source such as another laser light source, so that the phosphor layer absorbs the excitation light. Emits fluorescence. In this case, since the phosphor layer is formed in the minute region at the tip and the transition dipole corresponding to light emission is uniaxially oriented, fluorescence having a polarization characteristic is emitted from the minute region. Therefore, a near-field microscope or photon S
It is possible to provide a minute polarized light source adaptable to TM polarization observation.

In the first structure, the phosphor layer is formed on the outer wall of the minute polarized light source including the tip portion, and the quencher layer for quenching the fluorescence of the phosphor is formed on the phosphor layer around the tip portion. According to the preferable structure formed above, unnecessary fluorescence from around the tip portion is reduced, and a minute polarized light source with a small noise component can be realized.

Further, in the first structure, according to a preferable structure in which the phosphor molecule is a photochromic compound forming an aggregate, a minute polarized light source having a high extinction ratio can be realized.

In the first structure, the absorption layer is formed in contact with the phosphor layer, and energy transfer from the absorption layer that absorbs the excitation light causes polarized fluorescence to be emitted from the phosphor layer. According to the preferable configuration described above, a minute polarized light source having a good extinction ratio can be realized without using a photochromic compound.

According to the second aspect of the present invention,
When the tip portion is irradiated with excitation light from another light source such as a laser light source, the phosphor layer absorbs the excitation light and emits fluorescence.
In this case, since the phosphor molecules are not necessarily oriented, unpolarized fluorescence is emitted, but since specific polarized fluorescence is absorbed when passing through the uniaxially oriented absorption layer, fluorescence having polarization characteristics from the minute region is emitted. Is emitted. Therefore, it is possible to provide a minute polarized light source that can be applied to polarized light observation of a near-field microscope or Photon STM.

[0015]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the micro-polarized light source of the present invention, it is preferable that the phosphor layer is formed on the outer wall including the tip portion, and the quencher layer that quenches the fluorescence of the phosphor layer is formed around the tip portion. With this configuration, unnecessary fluorescent components from the vicinity of the tip can be reduced.

To make such a structure, the following may be performed. That is, first, the pipette is covered with a metal and the inside of the tip is filled with a polymer. Then
A quenching agent is vapor-deposited on this. Then, the tip of the pipette is irradiated with polarized laser to remove the quenching agent at the tip and to cause abrasion on the surface of the polymer filled inside the pipette. Then, phosphor molecules are vapor-deposited on the tip and the periphery thereof to form a uniaxially oriented phosphor layer on the tip. The reason for this is not clear, but there is a possibility that a fine structure is formed on the surface of the tip portion during ablation, which induces the orientation of the phosphor. Also, since the quencher at the tip is removed during abrasion,
The fluorescent substance at the tip portion emits fluorescence, but the fluorescent substance on the peripheral coating metal is efficiently quenched. As a result, unnecessary fluorescent components from around the tip can be reduced.

In the above-mentioned manufacturing method utilizing laser abrasion, it is preferable that the thickness of the phosphor layer is about 50 Å or less in order to enhance the efficiency of quenching by the quencher. Further, the phosphor layer may be formed by, for example, the Langmuir-Blodgett (LB) method. In addition, the quencher must be a compound having an absorption band that overlaps with the fluorescence band of the phosphor, and from the viewpoint of the efficiency of energy transfer from the phosphor to the quencher, it is an organic dye having a large absorption coefficient. Is preferred.

The phosphor used in the present invention may be a merocyanine dye, a cyanine dye, a xanthene dye, a squarinium dye, or a fluorescent organic substance of a polycyclic aromatic compound such as perylene. However, when the LB method is used, it is necessary to satisfy the condition of the balance between the hydrophilic group and the hydrophobic group in one molecule, such as having a long chain hydrocarbon group. Although an inorganic phosphor can be used, an organic substance having a large extinction coefficient and a large emission intensity per unit volume is preferable.

If a photochromic compound forming an aggregate is used as the fluorescent molecule, a minute polarized light source with a high extinction ratio can be realized. This photochromic compound is a compound that forms a bistable isomer upon irradiation with light. One of the isomers is called a colored body because it is colored, and the other is called a colorless body because it is colorless. In many cases, the colorless substance is more thermally stable. This colorless body absorbs ultraviolet light to become a colored body, and the colored body absorbs visible light and returns to a colorless body. There are some photochromic compounds in which a colored body forms an associated body, and they are stable both thermally and to light irradiation (Syn Solid Film 179, p. 21, 1985). For such photochromic compounds, 30 ° C to 40 ° C
The aggregate can be oriented by repeating the formation of the aggregate of colored bodies by irradiation of ultraviolet rays and the dissociation of the aggregates by irradiation of visible polarized light in the atmosphere heated above. This is because the aggregate grows around the aggregate that is oriented vertically to the polarized light that survives the irradiation of visible polarized light (Proceeding of Symposium on Future Electron Device).
135 pages 1988). When such a photochromic compound is used as a fluorescent molecule, a large number of layers are accumulated by repeating the accumulation by the LB method on the tip surface of the minute polarized light source. At the time of accumulation, the orientation of the molecules in each layer is different, but the oriented phosphor layer can be obtained by repeatedly performing the operation of forming an aggregate and dissociation. Further, even if the photochromic compound adsorbed on the coating metal is present, the photoreaction is suppressed due to energy transfer to the metal, etc., and the formation of an aggregate in the above-mentioned alignment layer forming process is difficult to proceed. Therefore, the photochromic compound easily exists as a monomer on the coating metal. However, this also returns to a colorless body that is thermally stable and does not absorb excitation light over time. Therefore, the fluorescence from the periphery of the tip portion becomes small, and the polarized fluorescence can be selectively obtained from the tip portion.

When a photochromic compound is used as the phosphor molecule, the phosphor layer may be formed not by the LB method but by the vapor deposition method. At this time, a large amount of photochromic compound may be present on the coated metal as compared with the case of the LB method, and even a photochromic compound that is originally difficult to form an aggregate on the metal may form a slight aggregate. May cause noise in the minute polarized light source. Therefore, it is preferable to suppress the formation of the aggregate by reducing the amount of ultraviolet rays to be irradiated and reducing the conversion rate to the colored body. As the photochromic compound, any compound that can reversibly form an aggregate may be used, but it is particularly preferable to use a spiropyran-based compound having an excellent ability to form an aggregate.

Further, as shown in FIG. 2, if the phosphor layer and the absorption layer are brought into contact with each other and formed at the tip of the minute polarized light source,
Even if a photochromic compound is not used as the phosphor molecule, a minute polarized light source having a good extinction ratio can be realized. This is because the phosphor layer formed by the LB method is well oriented. In many cases, a domain structure having a certain orientation is formed in the laminated condensed film on the water surface. This is particularly remarkable in the case of a fluorescent substance that forms an aggregate, and the size of the domain is large, and there are some that are close to several tens of μm to 1 mm. Therefore, it becomes possible to stack the phosphor layer oriented so as to cover the tip of the sub-micrometer minute polarized light source with a part of one domain.
Another important point is the light emitting mechanism of the minute polarized light source having the phosphor layer and the absorption layer. Unlike the structure described above, it is not the phosphor layer that absorbs the excitation light but the absorption layer. Then, the energy absorbed by the absorption layer moves to the phosphor layer, and the phosphor layer emits light. Therefore, although the phosphor layer is also formed around the tip of the light source, the absorption layer that absorbs the excitation light is provided only inside the tip, so that the tip emits light selectively.

A minute polarized light source having a structure in which an oriented absorption layer is provided outside the phosphor layer as shown in FIG. 2 is also preferable because it can obtain strong polarized fluorescence. Since the phosphor layer still exists inside the light source tip, the tip emits light selectively.

The present invention will be described in more detail with reference to specific examples. (Example 1) In Example 1, NK2684 (manufactured by Japan Photosensitive Dye), which is a kind of merocyanine dye, was used as a phosphor, and Rhodamine 19 (manufactured by Lambda Physic), which was a kind of xanthene dye, was used as a quencher. .

In the structure of the minute polarized light source described here, the phosphor layer is formed on the outer wall of the minute polarized light source including the tip portion, and the quencher layer for quenching the fluorescence of the phosphor is formed around the tip portion. It is characterized in that it can be manufactured by utilizing laser abrasion.

A method of manufacturing the minute polarized light source having the above structure will be described below with reference to FIG. First, 500 ml of Al (aluminum) was added to a glass pipette 1 having a tip opening diameter of 0.9 μm (thickness is about 1/3 of the diameter) obtained by stretching and cutting while softening by heating. Deposition was performed with a film thickness of angstrom.
Here, the vapor deposition was performed by a resistance heating method at a vacuum degree of 1 × 10 ⁻⁸ Torr. Next, a toluene solution of polyethersulfone as the polymer 2 was filled inside the tip of the pipette 1 and air-dried to solidify. Then, the quenching agent was vapor-deposited thereon by vapor deposition to cover the surface of the polymer 2 in the opening and the Al coating. Then, an excimer laser (308 nm, 10 nJ /
Pulse) to remove the quencher at the tip,
The surface of polymer 2 was abraded. Then, the phosphor was vapor-deposited thereon to a film thickness of 50 Å. As a result, the uniaxially oriented phosphor layer 3 was formed at the tip.

The minute polarized light source 4 manufactured in this way
In the arrangement shown in FIG. 3, the excimer laser (308 nm) 5 is irradiated from below, and the fluorescence 6 from the minute polarized light source 4 is received by the photomultiplier tube 9 through the polarizer 7 and the interference filter (585 nm) 8 and the photon Repeated integration at the count level. And the polarizer 7 in front of the photomultiplier tube 9
The change in the light amount was measured while rotating, and the ratio between the maximum light amount and the minimum light amount, that is, the extinction ratio (minimum light amount / maximum light amount) was obtained. The extinction ratio obtained was 0.62. Moreover, when the excitation light was applied only to the side surface of the pipette 1 coated with Al so that the tip of the pipette 1 would not be exposed to the excitation light, the fluorescence intensity was measured.
/ 100 or less. In FIG. 3, 10 is an excitation light source, 11 is a dichroic mirror, and 12 is a lens.

As described above, in Example 1, the layer of the quenching agent was removed by laser abrasion only at the tip portion, and the phosphor layer 3 was formed and oriented on the tip portion. The required fluorescence can be reduced.

(Example 2) In Example 2, a phosphor molecule represented by the following (Chemical Formula 1), which is a kind of spiropyran, is used as an absorber, and an aligned phosphor is formed by repeating formation and dissociation of an aggregate. A minute polarized light source that forms a layer will be described.

[0029]

[Chemical 1]

Here, the phosphor molecule shown in (Chemical Formula 1) is a photochromic compound that forms an aggregate. First,
A method for synthesizing this phosphor molecule will be described.

(Step 1) 42.3 g (26) of 2,3,3-trimethylindolenine [(1) in the following (Chemical Formula 2)]
6 mmol) and 101.1 g (266 mmol) of iodooctadecane [(2) of the following (Chemical Formula 2)] were dissolved in 200 ml of 2-butanone and heated under reflux for 40 hours. After distilling off 2-butanone, 1000
It was recrystallized from ethanol (9 ml), and a red-white solid, iodine salt of 1-octadecyl-2,3,3-trimethylindolenium [(3) of the following (Chemical Formula 2)] 91.5 g (197)
mmol, yield 63.9%) was obtained.

[0032]

[Chemical 2]

(Step 2) 1-octadecyl-
91.5 g (197 mmol) of an iodine salt of 2,3,3-trimethylindolenium [(3) in the following (Chemical Formula 3)] was dispersed in 100 ml of diethyl ether, and 3.8 of this was dispersed.
It was dispersed in 400 ml of an aqueous solution of N sodium hydroxide. 3.
After stirring for 5 hours, the oil layer was extracted with diethyl ether. After drying overnight with sodium hydroxide, the diethyl ether was distilled off, and 65.6 g (159 mmol) of 1-octadecyl-2-methylene-3,3-dimethylindoline [(4) of the following (Chemical Formula 3)] as a yellow liquid. , Yield 80.7%) was obtained.

[0034]

[Chemical 3]

(Step 3) 3-Chloromethyl-5-methoxysalicylaldehyde [(5) in Chemical Formula 4 below] 1
1.3 g (52.6 mmol) and 20.6 g of silver behenate
(52.6 mmol) were mixed, and the mixture was heated and distilled in benzene (heterogeneous system). After filtration for 40 hours, the filtrate was concentrated and then recrystallized with benzene: hexane = 1: 5 to give 3-docosanoyloxymethyl-5-nitro-salicylaldehyde [(6) in the following (Chemical formula 4)]. Yellow needle crystals 11.1
g (21.3 mmol, yield 40.5%) was obtained.

[0036]

[Chemical 4]

(Step 4) 2 g (4.9 mmo) of 1-octadecyl-2-methylene-3,3-dimethylindoline [(4) in the following (Chemical Formula 5)] synthesized in Steps 1 and 2.
l) and 2.1 g (4.1 mmol) of 3-docosanoyloxymethyl-5-nitro-salicylaldehyde [(6) of the following (Chemical Formula 5)] synthesized in Step 3 in 20 ml.
It was heated to reflux in ethanol for 1 hour. The dark green reaction solution was cooled and the deposited precipitate was recrystallized three times from 80 ml of ethanol to give a phosphor molecule (yellowish brown crystal) shown in the above (Chemical formula 1) [(Chemical formula 5) (7) below]. 2.5 g
(2.7 mmol, yield 65.9%) was obtained.

[0038]

[Chemical 5]

Next, a method of manufacturing the minute polarized light source having the above structure will be described. First, in the same manner as in Example 1, Al was vapor-deposited in a film thickness of 500 Å on a glass pipette having a tip opening having a diameter of 0.5 μm. Then, in the same manner as in Example 1, the inside of the pipette tip was filled with polymethylmethacrylate as a polymer. Then, only four monolayer films of the above phosphor were formed on this by the LB method. As the developing solution, a benzene solution in which the phosphor and octadecane had a molar ratio of 1: 2 was used. When the absorption spectrum was measured on the water surface, the fluorescent substance was colorless and did not form an aggregate in the formed condensed film.

Then, ultraviolet rays (366
(nm) and the temperature was raised to 40 ° C. At this time,
No formation of aggregates was observed on the Al film. Then, while maintaining the temperature at 40 ° C, a visible polarized laser (632.8
(nm, 1 mW) for 30 minutes. This was repeated 6 times. However, the irradiation time of the last visible polarized laser was 1 minute. At this time, no absorption of the colored body was observed on the Al film.

The extinction ratio (minimum light amount / maximum light amount) was determined in the same manner as in Example 1 using the minute polarized light source manufactured in this manner. A dye laser (540 nm) was used as an excitation light source, and an interference filter (635 nm) was used as a filter. The extinction ratio obtained was 0.08.

When the fluorescence intensity on the Al coating was examined in the same manner as in Example 1, it was 1/100 or less of the pipette tip. As described above, in Example 2, the photochromic compound forming an aggregate was used as the phosphor molecule,
A micro-polarized light source having a good extinction ratio could be realized by stacking the phosphor layers in a non-oriented state and then orienting them by forming and dissociating the associated body.

(Example 3) In Example 3, a minute polarized light source having a structure in which a phosphor layer and an absorption layer are formed adjacent to each other will be described. NK2879 (manufactured by Japan Photosensitive Dye), which is a kind of cyanine dye, was used as the fluorescent substance, and Rhodamine 6G (manufactured by Lambda Physic) was used as the absorber.
Here, the absorption band (590 nm) of the absorber and the fluorescence band (600 nm) of the phosphor 3 are in good agreement, which satisfies the condition for energy transfer.

A method of manufacturing the minute polarized light source having the above structure will be described below. First, in the same manner as in Example 1, Al was vapor-deposited in a film thickness of 500 Å on a glass pipette having a tip opening having a diameter of 0.5 μm. Then, in accordance with Example 1, a mixture of polyvinyl butyral as a polymer and the absorber was filled inside the tip of a pipette. Then, only one monolayer (molar ratio 1/5) of the phosphor and arachisanic acid was accumulated on this layer by the LB method.

The extinction ratio (minimum light amount / maximum light amount) was determined in the same manner as in Example 1 using the minute polarized light source manufactured in this way. Light (550 nm) having a wavelength absorbed by the absorber was irradiated as excitation light with a dye laser, and a sharp cut filter (600 nm) was used as a filter. The extinction ratio obtained was 0.06. Further, when the fluorescence intensity on the Al coating was examined in the same manner as in Example 1, it was 1/100 or less of the pipette tip.

As described above, in the third embodiment, since the absorption layer is in contact with the phosphor layer, the phosphor layer is polarized by the energy transfer from the absorption layer which absorbs the excitation light. Emits fluorescence. Further, it was possible to realize a minute polarized light source having a good extinction ratio without using a photochromic compound as a phosphor.

In the third embodiment, the phosphor layer is formed by the LB method, but the invention is not limited to this. For example, the vapor deposition method may be used. (Embodiment 4) In this Embodiment 4, a case where an oriented absorption layer is formed outside a phosphor layer will be described. As the absorber, the photochromic compound shown in (Chemical Formula 1) is used,
Sulforhodamine B (manufactured by Lambda Physic), which is a kind of xanthene dye, was used as the phosphor. Here, the absorption band of the absorber (618 nm) and the fluorescence band of the phosphor (620 nm)
nm), which satisfies the condition that the absorber serves as a polarization filter for fluorescence emitted from the phosphor.

A method of manufacturing the minute polarized light source having the above structure will be described below with reference to FIG. First, in the same manner as in Example 1, Al was vapor-deposited in a film thickness of 500 angstrom on a glass pipette 13 having a tip opening having a diameter of 0.8 μm. Then, in accordance with Example 1, a dispersion of the phosphor in polymethylmethacrylate as a polymer (phosphor layer 14) was filled inside the tip of the pipette 13. Then, 20 layers of the mixed monolayer of the above-mentioned absorber and stearic acid (molar ratio 1/2) were laminated thereon by the LB method, and the absorber was formed by the same method as in Example 2, that is, formation and dissociation of aggregates. The molecules were uniaxially aligned (alignment absorption layer 15).

The minute polarized light source 16 manufactured in this way
The extinction ratio (minimum light amount / maximum light amount) was determined in the same manner as in Example 1. Light having a wavelength (550 nm) absorbed by the phosphor layer 14 was irradiated as excitation light with a dye laser, and an interference filter (620 nm) was used as a filter. The extinction ratio obtained was 0.37. In addition, the measured light intensity was higher than that in Example 3 by two digits or more. Furthermore, when the fluorescence intensity on the Al film was examined in the same manner as in Example 1, it was 1/100 or less of the tip of the pipette 13.

As described above, in Embodiment 4, since the orientation absorption layer 15 is formed outside the phosphor layer 14, the minute polarized light source 16 having high light intensity can be realized.

In the fourth embodiment, the phosphor layer is formed by the LB method, but the present invention is not limited to this. For example, the vapor deposition method may be used. Further, in the above-described Examples 1 to 4, the case where the minute polarized light source is manufactured from the pipette type of which the inside is hollow is described, but the present invention is not necessarily limited to this type, and the inside of the needle is not hollow. It can also be manufactured using a thing.

[0052]

As described above, according to the first configuration of the minute polarized light source according to the present invention, the phosphor layer formed at the tip portion is irradiated with excitation light from another light source such as a laser light source. By doing so, the phosphor layer absorbs this and emits fluorescence. In this case, since the phosphor layer is formed in the minute region at the tip and the transition dipole corresponding to light emission is uniaxially oriented, fluorescence having a polarization characteristic is emitted from the minute region. Therefore, it is possible to provide a minute polarized light source that can be applied to polarized light observation of a near-field microscope or Photon STM.

In the first structure, the phosphor layer is formed on the outer wall of the minute polarized light source including the tip portion, and the quencher layer for quenching the fluorescence of the phosphor is formed on the phosphor layer around the tip portion. According to the preferable structure formed above, unnecessary fluorescence from around the tip portion is reduced, and a minute polarized light source with a small noise component can be realized.

Further, in the first configuration, according to the preferred configuration in which the fluorescent molecule is a photochromic compound forming an associate, a minute polarized light source with a high extinction ratio can be realized.

In the first structure, the absorption layer is formed in contact with the phosphor layer, and energy is transferred from the absorption layer that absorbs the excitation light so that polarized fluorescence is emitted from the phosphor layer. According to the preferable configuration described above, a minute polarized light source having a good extinction ratio can be realized without using a photochromic compound.

Further, according to the second structure of the minute polarized light source according to the present invention, by irradiating the tip portion with excitation light from another light source such as a laser light source, the phosphor layer absorbs the excitation light to cause fluorescence. Emit. In this case, since the phosphor molecules are not necessarily oriented, unpolarized fluorescence is emitted, but since specific polarized fluorescence is absorbed when passing through the uniaxially oriented absorption layer, it has polarization characteristics from a minute region. Fluorescence is emitted. Therefore, it is possible to provide a minute polarized light source that can be applied to polarized light observation of a near-field microscope or Photon STM.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a minute polarized light source according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the minute polarized light source according to the present invention.

FIG. 3 is a diagram showing an optical system for measuring an extinction ratio for an embodiment of a minute polarized light source according to the present invention.

FIG. 4 is a cross-sectional view showing an aperture transmission type minute light source in the prior art.

FIG. 5 is a sectional view showing a fluorescent light source of a downward excitation type in a conventional technique.

[Explanation of symbols]

 1, 13 Pipette 2 Polymer 3, 14 Phosphor layer 4, 16 Micro polarized light source 5 Excimer laser 6 Fluorescence 7 Polarizer 8 Interference filter 9 Photomultiplier tube 10 Excitation light source 11 Dichroic mirror 12 Lens 15 Orientation absorption layer

Claims (5)

[Claims] 1. A micro-polarized light source having a tip portion having a diameter of 1 μm or less, wherein a peripheral portion excluding the tip portion is covered with a metal, and a phosphor molecule having optical anisotropy on a surface of the tip portion is provided. A micro-polarized light source comprising a uniaxially oriented phosphor layer and irradiating excitation light from the outside to emit polarized fluorescence from the phosphor layer. 2. A phosphor layer is formed on an outer wall of a micro-polarized light source including a tip portion, and a quencher layer for quenching fluorescence of the phosphor is formed on the phosphor layer around the tip portion. The minute polarized light source according to 1. 3. The micro-polarized light source according to claim 1, wherein the fluorescent molecule is a photochromic compound forming an aggregate. 4. The micro-polarized light source according to claim 1, wherein an absorption layer is formed in contact with the phosphor layer, and energy is transferred from the absorption layer that has absorbed the excitation light to emit polarized fluorescence from the phosphor layer. . 5. A micro-polarized light source having a tip portion having a diameter of 1 μm or less, wherein a peripheral portion except the tip portion is covered with a metal, a phosphor layer is provided inside the tip portion, and an opening portion is provided. A minute polarization light source, wherein an absorption layer in which absorber molecules are uniaxially oriented is formed, and excitation light is irradiated from the outside to convert fluorescence emitted from the phosphor layer into fluorescence polarized through the absorption layer.