JP6682095B2 - Optical member and light guide member - Google Patents

Description

  The present invention relates to an optical member, a light guide member, and a method for producing an optical member, and more particularly to an optical member that is used adjacent to a light guide unit that transmits incident light, and that attenuates the incident light.

  Generally, the sensitivity of emission analysis using the emission phenomenon of substances, molecules and atoms is very high. In addition, analysis is also performed by irradiating a sample with light and using light emitted from the sample. Examples of such optical analysis include an absorbance method and a laser organic fluorescence method (Laser Induced Fluorescence: LIF).

  In recent years, there has been a demand for miniaturization of such an optical measuring device and an optical measuring device to the extent that they can be carried and to improve the measurement performance.

  Here, when the light measuring device is downsized, the distance between the light source for irradiating the sample with light and the detector for monitoring the observation light from the sample becomes closer in the device. A condenser lens and an optical filter are installed in the light guide path that constitutes the irradiation optical system that guides the irradiation light from the light source to the sample and the observation light collection optical system that guides the observation light from the sample to the detector. There are optical elements such as. Therefore, the influence of stray light, which may be noise in measurement, such as reflected light and scattered light generated when light travels through the light guide path in the device, becomes more remarkable as the device becomes smaller. Such stray light is also generated on the inner wall of the device housing.

  The inventors have conducted photo-induced fluorescence measurement in which an optical system and a monolithic housing are configured by using a resin containing a pigment in at least a part thereof in order to suppress the influence of stray light as much as possible and to realize miniaturization of an optical measurement device. (Patent Document 1) has been proposed. This concerns the LIF device.

  Specifically, it has the following features. (1) A resin transparent to the irradiation light and the observation light is filled in a part of the light guide path forming the irradiation optical system and the light guide path forming the observation light collecting optical system. (2) Resin is further provided so as to surround the transparent resin forming these light guide paths. This resin contains a pigment. (3) The pigment has a characteristic of absorbing stray light. The pigment content is set to an amount that absorbs at least all stray light. (4) The materials of the transparent resin and the pigment-containing resin are the same.

  With the above configuration, for example, the following actions and effects are exhibited. First, by using the same resin material for the transparent resin and the pigment-containing resin, light reflection and scattering are suppressed at the interface where the two resins contact. Further, the stray light incident on the pigment-containing resin is absorbed by the pigment. Therefore, it hardly returns to the transparent resin forming the light guide path. Furthermore, stray light does not leak from the pigment-containing resin to the outside. Therefore, the complicated multiple reflection of stray light hardly occurs. As a result, the observation light collection optics need not accommodate complex multiple reflections.

JP, 2014-032064, A Japanese Patent Application No. 2015-107930

  However, although the pigment is a particle and has a stray light absorbing property, a part of the stray light incident on the pigment is scattered. Depending on the relationship between the wavelength of stray light and the size of the pigment particles, part of the stray light may be Mie scattering, Rayleigh scattering, or geometrical scattering.

  The invention described in Patent Document 1 focuses on the absorption characteristics of the pigment. However, the effect of stray light scattering by pigment particles has not been sufficiently taken into consideration.

  In consideration of the influence of the scattering of stray light, the inventors have proposed an optical member or the like that can suppress the scattering of stray light due to the pigment even when it is used adjacent to a light guide section that transmits incident light. (Patent Document 2). Note that the technology described in Patent Document 2 is not known at the time of filing this application.

  Specifically, carbon black was used as the pigment dispersed in the transparent resin, and the particle size of carbon black capable of reducing the influence of scattering was defined. Further, it was found that the particle size was increased substantially due to the aggregation depending on the content (% by weight) of carbon black contained in the transparent resin, and the content of the carbon black pigment in the silicone resin was appropriately set. This makes it possible to suppress the influence of scattering when stray light enters the pigment.

  Carbon black, which is a carbon-based material, has a wavelength characteristic of absorbing stray light, and by appropriately defining the particle size and concentration, it is possible to suppress the influence of scattering when stray light enters the carbon black.

  However, it is unknown what kind of scattering suppressing effect can be expected for carbon-based materials other than carbon black. It is conceivable that different materials will have significantly different characteristics.

  Therefore, the present invention provides an optical member or the like capable of suppressing stray light scattering and attenuating the intensity of stray light by using a resin in which a pigment made of a carbon-based material other than carbon black is dispersed. With the goal.

  A first aspect of the present invention is an optical member that is used adjacent to a light guide portion that transmits incident light, and that diminishes the incident light, the optical member being provided in a specific region of a silicone resin. It is an optical member comprising a carbon nanotube dispersion portion in which carbon nanotubes are dispersed.

  A second aspect of the present invention is the optical member according to the first aspect, wherein the specific region includes the light guide portion and the optical portion when the optical member is used adjacent to the light guide portion. This is a region corresponding to the region from the boundary with the member to the depth of the absorption length of specific light.

  A third aspect of the present invention is the optical member according to the second aspect, wherein the specific light is noise light different from the incident light.

  A fourth aspect of the present invention is a light guide member that guides incident light, the light guide portion having at least a part of a silicone resin that transmits the incident light and is transparent to the incident light. A light guide member, which is adjacent to the light guide portion and includes a stray light absorbing portion having a carbon nanotube-dispersed silicone resin in which carbon nanotubes are dispersed in a silicone resin of the same material as the transparent silicone resin. .

  As a fifth aspect of the present invention, the optical member of the first aspect may be characterized in that the carbon nanotubes are dispersed in a specific region of the silicone resin. .

  According to each of the aspects of the present invention, a resin in which a carbon-based material other than carbon black is dispersed is used adjacent to a light guide section that transmits incident light, thereby achieving both stray light scattering suppression and stray light intensity attenuation. Is possible. This is an effect based on the optical characteristics of carbon nanotubes that the inventors have revealed through research and development.

  According to the second aspect of the present invention, it is easy to particularly suppress the scattering of light entering the optical member from the light guide section.

  According to the third aspect of the present invention, it becomes easier to specifically provide the optical member. Generally, the wavelength used for light measurement is approximately in the range of ultraviolet light to visible light (200 to 780 nm). In the light measurement, it becomes easy to adjust the optical member based on the wavelength of the noise light whose scattering should be suppressed.

It is a figure which shows the sample produced in order to implement the evaluation of the light-shielding property of the pigment-containing silicone resin (evaluation of the scattering characteristic). This is a system for measuring the angular characteristics of scattered light intensity used in this measurement. It is a figure which shows the angular characteristic distribution of the scattered light intensity in the sample whose carbon nanotube concentration is 0.17 wt%, 0.83 wt%, 1.7 wt%, and 10 wt%. It is a schematic diagram of the optical system for comparing the stray light absorption characteristics of an optical member, and is a figure of (a) straight line, (b) 45-degree bending, and (c) 90-degree bending optical system. It is a graph which shows the relationship between the bending angle of an optical member, and the attenuation rate of an incident laser beam.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiment of the present invention is not limited to the following examples.

  In order to evaluate the light-shielding property of the pigment-containing silicone resin (evaluation of scattering characteristics), a disc-shaped sample 1 as shown in FIG. 1 was prepared. The disc-shaped sample 1 is a disc-shaped transparent silicone resin, and has a transparent semicircular portion 3 made of a transparent silicone resin and a pigment semicircular portion 5 made of a silicone resin containing a pigment. As the transparent silicone resin, PDMS resin (manufactured by Shin-Etsu Silicone (registered trademark): Silicone impression material SIM-360) was used.

  The pigment-containing silicone resin was formed by dispersing the pigment in the PDMS. As the carbon-based pigment, carbon nanotubes (Flotube9000, manufactured by CNano, USA) were used. In order to compare the performance, carbon black (KE-COLOR-BL manufactured by Shin-Etsu Silicone (registered trademark)) was also used as a carbon-based pigment.

  As the disk-shaped sample 1, first, three types were prepared by changing the concentration of carbon nanotubes dispersed in PDMS. In addition, as a comparative example, one type of carbon black was prepared. Specifically, for those using carbon nanotubes, the concentration of carbon nanotubes dispersed in the PDMS was set to 0.17 wt%, 0.83 wt% and 1.7 wt%. In the case of using carbon black, the concentration of carbon black dispersed in the PDMS was set to 10 wt%. Further, the curing time of PDMS was set to 1 hour.

  The shape of the carbon nanotubes was almost uniform as a whole, the average diameter was 10 to 15 nm, and the average length was 10 μm.

  On the other hand, there are variations in the shape of carbon black. Observation of the PDMS resin in which the carbon black was dispersed revealed that the particle size of the carbon black was almost entirely within the range of about 0.5 to 2.0 μm, and the dispersion of the particle size was relatively small.

  First, the angular characteristics of the scattered light intensity in the samples with carbon nanotube concentrations of 0.17 wt%, 0.83 wt%, 1.7 wt% and carbon black concentration of 10 wt% were measured.

  FIG. 2 shows an angle characteristic measuring system 11 of scattered light intensity used for the measurement this time. As shown in FIG. 2, the disc-shaped sample 1 is installed on a rotary stage 15 having a rotary shaft 13.

  The rotary shaft 13 has a branch portion 17 extending from the rotary shaft 13 in a direction orthogonal to the axial direction of the rotary shaft 13. The branch portion 17 is connected to the column 21 of the light source support portion 19. The light source support portion 19 includes a column 21 and a light source fixing portion 23 branched from the column 21. A DPSS laser light source 25 that emits a laser beam having a wavelength of 532 nm is fixed to the light source fixing portion 23.

  As shown in FIG. 2, the laser beam 27 emitted from the DPSS laser light source 25 travels downward and is reflected by the reflection mirror 31 supported by the reflection mirror support portion 29 provided on the rotary shaft 13 of the rotary stage 15. It is folded back and enters the disc-shaped sample 1. Here, the reflection mirror 31 is adjusted so that the laser beam 27 is incident on the boundary surface 7 between the transparent semicircular portion 3 and the pigment semicircular portion 5 of the disk-shaped sample 1 at an incident angle of 45 degrees. There is.

  The disc-shaped sample 1 is composed of the transparent semicircular portion 3 and the pigment semicircular portion 5 as described above. Here, since the silicone resins forming the two semicircular portions are the same type of resin, they have the same refractive index. Therefore, the interface reflection of the laser beam 27 incident on the disk-shaped sample 1 at the boundary surface 7 basically does not occur.

  As described above, the laser beam 27 is incident on the pigment semicircular portion 5 without being interface-reflected at the boundary surface 7. The carbon-based material (carbon nanotube, carbon black) and the silicone resin are different in material and have different refractive indexes. Therefore, the laser beam 27 reaching the carbon-based material is absorbed or scattered by the carbon-based material.

The absorption coefficient of the carbon-based material is 7.2 × 10 ² / cm for the laser beam 27 having a wavelength of 532 nm. Therefore, the laser beam 27 reaching the carbon-based material is strongly absorbed by the carbon-based material. The laser beam 27 not absorbed by the carbon-based material is scattered in various directions by the carbon-based material. Of the scattered light, the light traveling from the pigment semicircular portion 5 to the transparent semicircular portion 3 is emitted to the outside from the transparent semicircular portion 3.

  On the side where the laser beam 27 is emitted to the outside from the transparent semicircular portion 3, as shown in FIG. 2, a slit 33 having an opening portion having a width of 2 mm and a length of 30 mm in the vertical direction is transmitted through the slit 33. A scattered light measuring unit 39 having a condenser lens 35 for condensing light and a detector 37 including a photodiode for measuring the intensity of the laser beam 27 condensed by the condenser lens 35 is provided. The scattered light measuring unit 39 limits the light incident on the detector 37 by the slit 33.

  On the other hand, as described above, the disk-shaped sample 1, the DPSS laser light source 25, and the reflection mirror 31 are integrated by the light source support portion 19 and the reflection mirror support portion 29 that are connected to the rotating shaft 13 by the branch portion 17. Is held. Therefore, even if the rotating shaft 13 is rotated, the incident angle of the light from the DPSS laser light source 25 incident on the disk-shaped sample 1 is maintained.

  By rotating the rotary shaft 13 of the rotary stage 15 in this state, a part of the scattered light of the laser beam 27 emitted from the transparent semicircular portion 3 to the outside while maintaining the above-mentioned incident angle is scattered light measuring unit. It is possible to adjust so that the light is guided to the slit 33 of 39.

  As described above, the slit 33 fixes the incident angle of the incident light, as shown in FIG. Therefore, by rotating the rotary shaft 13 of the rotary stage 15, only the intensity of light scattered in a specific angle direction can be measured by the scattered light measuring unit 39. That is, it is possible to measure the angular characteristic of the scattered light intensity emitted from the disc-shaped sample 1.

  FIG. 3 is a diagram showing an angular characteristic distribution of scattered light intensity in a sample having a carbon nanotube concentration of 0.17 wt%, 0.83 wt%, 1.7 wt%, and a carbon black concentration of 10 wt%.

  In the angle characteristic distribution shown in FIG. 3, the length (distance) from the origin 0 to each curve indicates the scattered light intensity. Therefore, the area formed by each curve shows the integrated reflection intensity (scattering intensity) of the laser beam incident on the sample.

  As is clear from FIG. 3, when the carbon nanotubes of three types of concentrations are used as pigments, the integrated reflection intensity (scattering intensity) is smaller than that when carbon black is used as the pigment.

  As proposed in Patent Document 2, in order to absorb stray light in a light guide made of a transparent silicone resin, the light guide is surrounded by a silicone resin in which a pigment (carbon black) is dispersed, When the stray light from the above is absorbed by the pigment-dispersed silicone resin, the integrated reflection intensity (scattering intensity) is small when the carbon black concentration is 10 wt%, and the pigment-dispersed silicone resin for absorbing the stray light can perform a sufficient function. .

  When carbon nanotubes are used as a pigment, the scattered light intensity is smaller than when carbon black having a concentration of 10 wt% is used as described above. Therefore, the silicone resin for absorbing stray light in which carbon nanotubes are dispersed uses carbon black. It is considered to be even better and able to perform a sufficient function.

  The reason why the integrated reflection intensity (scattering intensity) when the carbon nanotube is used as the pigment is significantly smaller than the integrated reflection intensity (scattering intensity) when the carbon black is used is not necessarily clear, but is considered as follows. To be

  Carbon black generally has a particle structure, but carbon nanotubes have a linear structure. Therefore, it is considered that the relative relationship between the direction (light distribution) of the carbon nanotubes dispersed in the silicone resin and the traveling direction of scattered light is suitable for improving the effect of suppressing scattering.

  Further, comparing the cases where the carbon nanotube concentrations are 0.17 wt%, 0.83 wt% and 1.7 wt%, as is apparent from FIG. 3, the integrated reflection intensity (scattering intensity) has a concentration of 0.83 wt%. Is the smallest. Therefore, when carbon nanotubes are used, it is considered that the optimum carbon nanotube concentration capable of minimizing the integrated reflection intensity (scattering intensity) exists within the concentration range of 0.17 to 1.7 wt%. .

  As described above, when the carbon nanotubes are used as the pigment, the integrated reflection intensity (scattering intensity) is smaller than that when the carbon black is used as the pigment. It is considered to be even better than the case of using carbon black and capable of performing a sufficient function.

  In order to confirm this, an optical system as shown in FIG. 4 was constructed and the stray light absorption characteristics of the stray light absorbing silicone resin in which carbon nanotubes were dispersed and the stray light absorbing silicone resin in which carbon black was dispersed were compared.

  As shown in FIG. 4, a light guide path made of a transparent PDMS resin having an incident surface area of 2 mm × 1 mm and a length of 50 mm and a pigment-dispersed silicone resin in which a carbon-based pigment surrounding the light guide path is dispersed. An optical member having a two-layer structure is prepared. In FIG. 4, the upper surface side of the light guide path made of transparent PDMS resin is exposed for easy understanding, but in reality, the portions other than both ends of the transparent light guide path are surrounded by the pigment-dispersed silicone resin.

  In the optical system having the above structure, since the transparent silicone resin and the pigment-dispersed silicone resin forming the light guide path are the same material, no interface reflection of light occurs at the interface between the two resins. Therefore, stray light that enters the pigment-dispersed silicone resin from the light guide path enters the pigment-dispersed silicone resin as it is, and most of it is absorbed by the carbon-based pigment.

  In the optical member as shown in FIG. 4A, a laser beam having a wavelength of 532 nm and a beam diameter of 1 mm, for example, enters from the A end of the optical member. Even if the light guide portion is not a structure filled with a transparent PDMS resin but a simple cavity, if the spread of the laser light and the absorption by the light guide itself are ignored, a part of the laser light becomes a pigment-dispersed PDMS resin. Therefore, when the laser beam travels from the A end to the B end of the light guide path, the laser beam is not attenuated.

  On the other hand, as shown in FIGS. 4B and 4C, when the optical member is bent at 45 degrees and 90 degrees, the laser beam incident from the end A of the light guide path collides with the pigment-dispersed PDMS resin, and the collided laser beam. The laser beam is attenuated because most of the beam is absorbed by the pigment dispersed PDMS. The larger the bending angle of the optical member, the higher the ratio of the laser beam incident from the A end of the light guide path to the pigment PDMS resin surrounding the light guide path. That is, the intensity of the laser beam reaching the B end becomes small.

Therefore, three optical members (optical member 1, optical member 2, and optical member 3) were prepared, and the relationship between the bending angle of the optical member and the attenuation rate of the incident laser beam was examined. The configurations of the three optical members are as follows.
The optical member 1 has a structure in which the light guide path is hollow, and carbon black having a concentration of 10 wt% is dispersed in the pigment-dispersed PDMS.
The optical member 2 has a structure in which a transparent PDMS resin is filled in the light guide path, and carbon black having a concentration of 10 wt% is dispersed in the pigment-dispersed PDMS.
The optical member 3 has a structure in which the light guide path is filled with a transparent PDMS resin, and has a structure in which carbon nanotubes having a concentration of 0.83 wt% are dispersed in the pigment-dispersed PDMS.

  FIG. 5 shows the relationship between the bending angle of the optical member and the attenuation rate of the incident laser beam for the optical member 1, the optical member 2, and the optical member 3. In the optical member 1 (hollow light guide / carbon black dispersed resin), the laser beam intensity at the B end when the bending angle was 0 degree was 100%.

  As shown in FIG. 5, in the case of the optical member 1 in which the light guide path is hollow and the hollow is surrounded by the pigment dispersion resin in which carbon black is dispersed, the laser beam at the B end when the bending angle is 30 degrees. Although the intensity is attenuated to 10%, the laser beam intensity is around 10% even when the bending angle is 90 degrees. That is, the attenuation rate remains 1/10 (OD = 1) and does not change much. It is considered that this is because, in the laser beam incident from the A end, the s-polarized component having a large Fresnel reflection is guided to the B end due to reflection on the surface of the pigment-dispersed PDMS resin surrounding the hollow light guide path.

  On the other hand, in the case of the optical member 2 in which the light guide path is made of transparent PDMS resin and the cavity is surrounded by the pigment dispersion resin in which carbon black is dispersed, the laser beam intensity when the bending angle is 30 degrees is about 6%. The attenuation rate is about 1/6 (OD = 1.2), the laser beam intensity is about 0.005% when the bending angle is 60 degrees, and the attenuation rate is about 5/1000 (OD = about 2.3). ) Became.

  The reason why the optical member 2 has a better attenuation factor than the optical member 1 is that in the optical member 2, the transparent PDMS resin and the carbon black pigment-dispersed PDMS resin forming the light guide path are the same material. Therefore, it is considered that the interface reflection of light does not occur at the interface between the two resins. That is, it is considered that the Fresnel reflection of the S-polarized component as in the case of the optical member 1 does not occur in the optical member 2.

  Further, in the case of the optical member 3 in which the light guide path is made of transparent PDMS resin and the cavity is surrounded by the pigment dispersion resin in which carbon nanotubes are dispersed, the laser beam intensity is already 0.005 when the bending angle is 30 degrees. When the bending angle was 45 degrees, the laser beam could not be observed when the bending angle was 45 degrees. Since the observation limit of the measuring instrument was about OD = 5.5, it is possible that OD = 6 could be achieved when the bending angle was 45 degrees.

  Thus, it was found that when the bending angle is 30 degrees or more, when the pigment-dispersed PDMS is carbon nanotubes, a dramatic effect of quenching stray light is obtained as compared with when the pigment is carbon black. It is considered that this is because the carbon nanotube has a smaller integrated reflection intensity (scattering intensity) than the carbon black as described above, and therefore the intensity of scattered light reaching the B end of the optical member is extremely low.

  That is, when carbon nanotubes are used as the carbon-based pigment and the resin portion in which the carbon nanotubes are dispersed is used adjacent to the light guide portion that transmits incident light, the suppression of scattering of stray light is better than when the pigment is carbon black. Is more effective, and the intensity of stray light can be attenuated even better.

DESCRIPTION OF SYMBOLS 1 ... Disc-shaped sample, 3 ... Transparent semicircular part, 5 ... Pigment semicircular part, 7 ... Boundary surface, 11 ... Angular characteristic measuring system, 13 ... Rotation axis, 15 ... Rotating stage, 17 ... Branching part, 19 ... Light source supporting part, 21 ... Strut, 23 ... Light source fixing part, 25 ... DPSS laser light source, 27 ... Laser beam , 29 ... Reflecting mirror support part, 31 ... Reflecting mirror, 33 ... Slit, 35 ... Condensing lens, 37 ... Detector, 39 ... Scattered light measuring part

Claims (4)

Surrounding the other end portions of the light guide portion for transmitting the incoming Shako, an optical member for dimming the incident light,
The optical member comprises a carbon nanotube dispersion portion in which 0.17 to 1.7 wt% of carbon nanotubes are dispersed in a specific region in a silicone resin.   The specific region is a region corresponding to a region from a boundary between the light guide portion and the optical member to a depth of a specific light absorption length when the optical member is used adjacent to the light guide portion. The optical member according to claim 1, wherein   The optical member according to claim 2, wherein the specific light is noise light different from the incident light. A light beam member for guiding the incoming Shako,
A light guide section which transmits the incident light and has at least a part of a silicone resin transparent to the incident light;
A stray light absorbing portion that surrounds the light guide portion other than both ends and has a carbon nanotube-dispersed silicone resin in which 0.17 to 1.7 wt% of carbon nanotubes are dispersed in a silicone resin of the same material as the transparent silicone resin. A light guide member, comprising: