JP3365809B2 - Measurement device using surface plasmon resonance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring apparatus using surface plasmon resonance for measuring the state of a measurement sample with high sensitivity.

[0002]

2. Description of the Related Art In recent years, several measuring devices utilizing surface plasmon resonance have been developed as devices for measuring information near the surface of a dielectric sample and film thickness distribution of a dielectric thin film with high sensitivity.

For example, "Thin Solid Films, 187, (1990) 3
49-356 ”includes Langmuir Blodgett film (LB
It has been reported that the surface plasmon was induced by parallel light using a film) as a sample, and the intensity distribution of the reflected light was detected to observe the film thickness distribution of the LB film. Also, `` Optics, 19, (1
990) 682-686 ", the onion is used as a sample, surface plasmons are induced by converging light, and the angular distribution of the reflected light intensity is detected using a one-dimensional image sensor.
It has been reported that the onion surface cells were observed as a pseudo-color image by mapping the angular distribution by color coding while performing two-dimensional scanning with the Y stage.

In this type of measuring apparatus, generally, an optical prism is used to excite surface plasmons. As an example of the arrangement of the prism, "Z. Physik, 216, 398" is used.
(1968) ”, an Otto arrangement in which a prism and a metal face each other with a small gap of 1 μm or less, and“ Z.Physik, 241,313 (1971) ”reported. As described above, there is a Kretschmann arrangement in which a metal on a thin film is directly attached to a prism.

[0005]

A measuring apparatus utilizing surface plasmon resonance is capable of improving the state of a biological membrane, a pseudo-biological membrane such as a synthetic bilayer membrane or an LB membrane, and an organic thin film such as a liquid crystal alignment layer. It has the feature that it can be observed with sensitivity.

However, since the organic thin film as described above is often oriented with a certain inclination, the above-mentioned document "Thin Solid Films, 187, (1990) 349-356", "Optics, 1".
As disclosed in "(9) (1990) 682-686", there is a problem in that the optical anisotropy caused by the molecules being oriented cannot be detected in the configuration in which light is incident only from one direction.

The present invention has been made to solve the above-mentioned problems, and its first object is to provide a surface plasmon that is appropriately configured so as to detect the orientation state of molecules of a measurement sample by using the Ot arrangement. It is to provide a measuring device that utilizes resonance.

A second object of the present invention is to provide a measuring apparatus utilizing surface plasmon resonance, which is appropriately constructed so as to detect the orientation state of molecules of a measuring sample by using the Creshmann arrangement.

[0009]

In order to achieve the first object, in the present invention, a measurement sample is held on a metal surface, and an optical prism is provided above the measurement sample via an air dielectric. Arranged, the surface plasmon resonance is induced on the surface of the metal by the evanescent light generated when polarized light is incident on the optical prism under the condition of total reflection, and the reflected light is detected to measure the state of the measurement sample. In the measuring device using the surface plasmon, the metal is held on a rotatable rotary stage, and the incident surface of light on the measurement sample is rotated by this rotary stage to measure the orientation state of the measurement sample. To be configured.

In order to achieve the above second object, according to the present invention, a measurement sample is held on at least one surface of a substrate transparent to light of a specific wavelength through at least a metal thin film, and the other of the substrates is held. An optical prism is held on the surface, polarized light is incident on the metal thin film through the optical prism and the substrate under conditions of total reflection to induce surface plasmon resonance, and the reflected light is detected to measure the measurement sample. In a measuring device using surface plasmon that is adapted to measure the state of, holding the substrate on a rotatable rotary stage,
The rotation stage is configured to rotate the light incident surface on the measurement sample so that the orientation state of the measurement sample can be measured.

[0011]

In the first aspect of the invention, the measurement sample is rotated by the rotary stage. Therefore,
By aligning the light irradiation spot with the rotation axis of the rotary stage, the light incident surface can be rotated, and thus the orientation of the measurement site can be detected.

Further, in the second invention, the measurement sample is rotated by the rotary stage integrally with the substrate, the metal thin film and the optical prism. Therefore, if a conical or hemispherical prism is used as the optical prism and the irradiation spot of the light on the measurement sample is aligned with the rotation axis of the rotating stage, the light incident surface can be rotated. Can be detected.

[0013]

1 is a sectional view showing a first reference example of a measuring apparatus developed in connection with the present invention. This measuring device 1
Is to measure a dielectric thin film on a metal surface using an Ot arrangement, and the measured dielectric thin film 2 is held in contact with one surface of the metal 3. The metal 3 is held on the piezoelectric body 5 arranged on the XY stage 4. An optical prism 6 is arranged above the dielectric thin film 2 with a slight gap, and a monochromatic laser light source 7 to a polarizing plate 8, a beam expander 9, a diaphragm 10 and a condenser lens 11 are arranged in the optical prism 6. Then, the P-polarized convergent light is incident thereon, the evanescent light generated thereby induces surface plasmon resonance on the surface of the metal 3, and the reflected light is arranged on the focal plane thereof through the ND filter 12 and the cylindrical lens 13. The intensity distribution of the reflected light is obtained by detecting with the one-dimensional photodiode array 14.

Here, the one-dimensional photodiode array 1
4 indicates that each element corresponds to the reflection angle of light, so that the element that minimizes the reflected light generated by surface plasmon resonance is detected based on the output of each element, and the reflection angle of the absorption peak is calculated from the element position. Then, the incident angle at which the surface plasmon resonance occurs, that is, the resonance angle is detected.

The XY stage 4 and the piezoelectric body 5 are controlled by a control device such as a personal computer (not shown), and the XY stage 4 is two-dimensionally driven via a pulse motor (not shown), so that the dielectric thin film 2 is removed. A condition in which optimum surface plasmon resonance is generated by the piezoelectric body 5 every two-dimensional scanning and one step movement in the X or Y direction (the curve measuring the incident angle dependence of reflectance shows a deep valley and a half width. Is set to be a narrow curve), the distance between the optical prism 6 and the metal 3 is adjusted. The output of the one-dimensional photodiode array 14 is A / D-converted and then taken into a signal processing device (not shown), where the angle distribution is color-coded and mapped, and a CRT (not shown) is displayed as a grayscale image or a pseudo-color image. ) Display above.

In FIG. 1, the dielectric thin film 2 needs to have a film thickness equal to or less than the wavelength of incident light. Also, the metal 3 is
As described in "Surface, 20, 6, (1982) 289-304", the real part of complex permittivity is negative and large, Ag, Au, Cu, Zn, A
l and K are desirable, especially Pd, from the relationship with the size of the imaginary part.
Ni and Fe are not desirable. Further, the metal 3 can be composed of an alloy composition, but when Pd is mixed with Ag,
The specification of this alloy is not preferred because the surface plasmon resonance disappears. Further, the metal 3 is a bulk metal such as a metal plate or an electrode, vapor deposition, sputtering or plasma CVD.
It is also possible to form a thin film formed by, for example, a Cr film, for example, an extremely thin film, and a multilayer film in which Au or the like is formed thereon.

In FIG. 1, the monochromatic laser light source 7 is used.
May be one that emits randomly polarized light or one that emits linearly polarized light. However, if one that emits linearly polarized light is used, the polarizing plate 8 can be omitted. Further, instead of the monochromatic laser light source 7, a white light source may be used as a light source, and the white light may be converted into monochromatic light by a monochromator. Furthermore, diaphragm 1
0, the ND filter 12, the cylindrical lens 13,
It can be omitted.

According to the measuring apparatus 1 shown in FIG. 1, the distance between the optical prism 6 and the metal 3 can be controlled at the nanometer level with a simple structure in which the piezoelectric body 5 is provided. All measurements can be performed easily.

FIG. 2 is a sectional view showing the first embodiment of the present invention. The measuring apparatus 20 is the measuring apparatus 1 shown in FIG. 1 in which the XY stage 4 is provided on a rotary stage 21. Here, the rotation stage 21 has its rotation axis aligned with the center of a spot of irradiation light formed in a portion of the optical prism 6 facing the dielectric thin film 2.

According to this embodiment, the dielectric thin film 2 is XY
After two-dimensionally scanning with the stage 4, the film state is imaged and measured, and then the XY stage is moved to move the XY stage so that incident light is radiated to the site where the orientation state is to be measured.
By rotating 1 the surface on which the light is incident can be rotated and the orientation of the measurement site can be detected.

FIG. 3 is a sectional view showing a second embodiment of the present invention. This measuring device 30 measures the dielectric on the metal surface using the Creshmann arrangement. The measurement dielectric sample 31 is held on one surface of the transparent substrate 32 via the metal thin film 33. On the other surface of the transparent substrate 32, a hemispherical optical prism 35 is provided via a matching oil 34, and the monochromatic laser light source 7 to the polarizing plate 8, the beam expander 9, the diaphragm 10, the condenser lens 11, the optical prism 35. , Matching oil 34 and transparent substrate 3
P-polarized convergent light is made incident on the metal thin film 33 via 2 to induce surface plasmon resonance, and the reflected light is passed through the ND filter 12 and the cylindrical lens 13 and arranged on the focal plane of the one-dimensional photodiode array 14. And the intensity distribution of the reflected light is obtained.

Here, the one-dimensional photodiode array 1
4 indicates that each element corresponds to the reflection angle of light, so that the element that minimizes the reflected light generated by surface plasmon resonance is detected based on the output of each element, and the reflection angle of the absorption peak is calculated from the element position. Then, the incident angle at which the surface plasmon resonance occurs, that is, the resonance angle is detected.

The transparent substrate 32 is arranged on the rotary stage 21 via a spacer 36, and the optical prism 35 is provided with a spot of irradiation light on the dielectric sample 31 and the rotary stage 21.
Arrange them so that they are in the same position as the rotation axis of. In this way, by rotating the dielectric sample 31, the transparent substrate 32, the metal thin film 33, and the optical prism 35 integrally by the rotary stage 21, the surface on which the light is incident is rotated and the orientation of the measurement site is detected. To do.

In this embodiment, the metal thin film 33 is
As described in “Surface, 20, 6, (1982) 289 −304”, the real part of the complex permittivity is negative and large Ag, Au, Cu, Z
n, Al, K are desirable, especially from the relationship of the size with the imaginary part,
Pd, Ni, Fe are not desirable. In addition, this metal thin film 33
Can be composed of an alloy composition, but when Pd is mixed with Ag, the surface plasmon resonance disappears, so the specification of this alloy is not preferable. Furthermore, the metal thin film 33
In order to improve the adhesion to the transparent substrate 32, for example, a Cu film is formed extremely thin on the transparent substrate 31 and the Cu film is formed thereon.
You may comprise by the multilayer structure which formed the Au film etc. Further, the optical prism 35 is not limited to the hemispherical shape, and a conical shape may be used.

According to this embodiment, the rotation stage 21 is provided in the Creshmann arrangement measuring device in a simple structure.
The orientation of the measurement site can be detected by rotating the surface on which the light is incident.

FIG. 4 is a sectional view showing a second reference example of the measuring apparatus developed in relation to the present invention. This measuring device 4
In the measuring device 1 shown in FIG. 1, 0 is a piezoelectric body 41 connected to the one-dimensional photodiode array 14, and the expansion and contraction of the piezoelectric body 41 causes each one-dimensional photodiode array 14 corresponding to the reflection angle of light. The position of the element is slightly moved to obtain a more precise angular resolution.

In FIG. 4, a microscope objective lens having a numerical aperture of 0.28 and a magnification of 10 is used as the condenser lens 11, and a 60 ° prism made of BK-7 is used as the optical prism 6.
A cylindrical lens 13 having a lens width of 50 mm and a focal length of 147.6 mm is used, and the one-dimensional photodiode array 14 has a 14 μm pitch formed by a photodiode array of 9 μm per element and a channel stopper (separation region) of 5 μm. A device having 2048 elements (MN3643D manufactured by Matsushita Electronics Co., Ltd.) is used.

In such a structure, when the one-dimensional photodiode array 14 is fixed, the angular resolution is 0.
Although it is 004 °, when the one-dimensional photodiode array 14 is slightly moved by 7 μm by the piezoelectric body 41, the angular resolution is doubled to 0.002 °, and when it is further moved by 3.5 μm back and forth, the angular resolution is increased. It is quadrupled to 0.001 °. Therefore, even when there is a resonance angle between the elements of the one-dimensional photodiode array 14 or when the resonance angle moves during that time, accurate detection is possible.

In FIG. 4, the minute movement of the one-dimensional photodiode array 14 by the piezoelectric body 41 is not limited to the above example, but may be set appropriately according to the pitch interval of the elements of the one-dimensional photodiode array 14 and the measurement purpose. You can Further, instead of the piezoelectric element 41, another known displacement means may be used to displace the one-dimensional photodiode array 14.

The present invention is not limited to the above-described embodiments, but various modifications and changes can be made. For example, in the first embodiment, the piezoelectric body 5 is used to control the distance between the optical prism 6 and the dielectric thin film 2, but the piezoelectric body 5 may be replaced by a known displacement means. Further, the configuration in which the one-dimensional photodiode array 14 is displaced as in the second reference example can be applied to the first and second examples.

[0031]

As described above, according to the present invention, the simple structure of holding the measurement sample on the rotary stage allows
The orientation state of molecules of the measurement sample can be detected by measurement using surface plasmon resonance.

[Brief description of drawings]

FIG. 1 shows a first measuring device developed in connection with the present invention.
It is sectional drawing which shows a reference example.

FIG. 2 is a sectional view showing a first embodiment of the measuring apparatus according to the present invention.

FIG. 3 is likewise a sectional view showing a second embodiment.

FIG. 4 shows a second measuring device developed in connection with the present invention.
It is sectional drawing which shows a reference example.

[Explanation of symbols]

2 Dielectric thin film 3 metal 4 XY stage 5 Piezoelectric body 6 Optical prism 7 Monochromatic laser light source 8 Polarizer 9 beam expander 10 aperture 11 Condensing lens 12 ND filter 13 Cylindrical lens 14 One-dimensional photodiode array 20 Measuring device 21 rotating stage 30 measuring devices 31 Dielectric sample 32 transparent substrate 33 Matching oil 35 Optical prism 36 Spacer

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Seiji Kondo 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Takayuki Okamoto 2-1, Hirosawa, Wako, Saitama Prefecture In-house (72) Ichiro Yamaguchi 2-1-1 Hirosawa, Wako-shi, Saitama Physics and Chemistry Research Office (72) Inventor Masatsugu Shimomura 2-24-48-103 Nakamachi, Koganei-shi, Tokyo (56) Reference JP-A-2-128111 (JP, A) JP-A-5-13033 (JP, A) JP-B 1-222589 (JP, B2) Y SUZUKI et al., "ENHAN CEMENT OF THE IR A BSORPION OF A (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 G01N 21/27

Claims (3)

(57) [Claims] 1. When a measurement sample is held on the surface of a metal and an optical prism is arranged above the measurement sample via an air dielectric, when polarized light is incident on the optical prism under the condition of total reflection. In the measuring device using the surface plasmon, which induces surface plasmon resonance on the surface of the metal by the evanescent light generated in, and measures the state of the measurement sample by detecting the reflected light, the metal is rotatable. A measuring apparatus, which is configured to be held on a rotating stage, and to rotate an incident surface of light on the measuring sample by the rotating stage to measure an orientation state of the measuring sample. 2. A measurement sample is held on one surface of a substrate transparent to light of a specific wavelength through at least a metal thin film, and an optical prism is held on the other surface of the substrate.
A surface adapted to inject polarized light into the metal thin film through the optical prism and the substrate under the condition of total reflection to induce surface plasmon resonance, and detect the reflected light to measure the state of the measurement sample. In a measuring device using plasmons, the substrate is held on a rotatable rotary stage, and the plane of incidence of light on the measurement sample is rotated by the rotation stage so that the orientation state of the measurement sample can be measured. A measuring device characterized in that 3. The measuring device according to claim 2, wherein the optical prism is a prism having a conical shape or a hemispherical shape.