JP2004347412A - Spectrometric device for gel-like sample - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectrometric device capable of performing accurate spectrometry even to a self-organizing sample, a gel like sample or the like. <P>SOLUTION: This spectrometric device 10 is equipped with a light irradiation part 12 for emitting monochromatic light having a wavelength selected from a plurality of wavelengths in order to perform wavelength scanning, an optical path changing part 16 for changing the course of light emitted from the light irradiation part 12, a polarized light modulation part 14 for modulating periodically the polarization state of the light whose course is changed by the optical path changing part 16, a rotating sample stand 18 rotatable on a horizontal plane around the optical axis as the center axis, and a photodetector 22 for detecting transmitted light transmitted through the sample 24 on the rotating sample stand 18. The device is characterized by irradiating light in the horizontal direction by the light irradiation part 12, changing the traveling direction of light, which is the light directed in the horizontal direction, in the vertical direction by the optical path changing part 14, and irradiating the sample installed horizontally on the rotating sample stand 18 with the light from the vertical direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spectrometer and, more particularly, to an improvement in a sample holding mechanism.
[0002]
[Prior art]
Measuring spectra such as optical rotation, dichroism, and birefringence of a substance is important for examining the optical properties and other information of the substance. In particular, this is an important measurement for examining the arrangement and orientation at the molecular level in a self-assembled sample. Examples of such spectrometers for measuring circular dichroism and the like include those described in Patent Documents 1 to 4.
[0003]
[Patent Document 1]
JP 2001-337035 A [Patent Document 2]
JP 2001-31683 A [Patent Document 3]
JP 2001-31684 A [Patent Document 4]
Japanese Patent Application Laid-Open No. 2002-313024
[Problems to be solved by the invention]
However, when the sample is in a gel state, a measurement error may be given to circular dichroism or optical rotation dispersion. In particular, the problem of the measurement error has been serious in an attempt to measure a self-assembled sample, which has been increasing in importance in recent years, and in observing a molecular level orientation and arrangement in a gel.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a spectrometer capable of performing accurate spectrometry even on a self-organizing sample, a gel sample, and the like.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a spectrometer of the present invention includes a light irradiation unit that emits monochromatic light having a wavelength selected from a plurality of wavelengths for performing wavelength scanning, and a light emitted from the light irradiation unit. An optical path changing unit for changing the path of light, a polarization modulator for periodically modulating the polarization state of light whose path has been changed by the optical path changing unit, and a rotation rotatable in a horizontal plane with the optical axis as a central axis. A sample stage; and a photodetector for detecting transmitted light transmitted through the sample on the rotating sample stage. Then, the light is irradiated in the horizontal direction from the light irradiation unit, and the light traveling in the horizontal direction is changed in the traveling direction of the light in the vertical direction by the optical path changing unit, and the sample is set horizontally on the rotating sample stage. Irradiating light from a vertical direction.
[0006]
In the above-described spectrometer, it is preferable that the optical path changing unit is configured by a total reflection prism or a mirror, and reflects the light traveling in the horizontal direction by the total reflection prism or the mirror to change the traveling direction to the vertical direction.
Further, in the above-described spectrometer, the sample is irradiated with the light whose polarization state is modulated, and the transmitted light from the sample is measured, whereby circular dichroism or optical rotation dispersion or linear dichroism of the sample is measured. Linear birefringence can be suitably measured.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
As described above, when the sample is a gel or the like, a measurement error may occur in circular dichroism or optical rotation dispersion. The present inventors have considered that the cause of the measurement error is caused by the occurrence of a vertical density gradient or a thickness gradient caused by gravity. In other words, signals such as linear dichroism and linear birefringence caused by the density gradient and the thickness gradient described above are generated in addition to the sample-specific optical rotatory dispersion and the like, and this signal causes a measurement error. is there.
[0008]
A conventional spectrometer has a configuration in which a light beam is irradiated in the horizontal direction due to space limitations, and the sample is inevitably placed vertically for measurement. Therefore, the light transmitted horizontally through the sample is measured, and is affected by the gravitational field as described above. In particular, proteins such as β-amyloid and BSA are easily aggregated and easily affected by gravity.
From the above considerations, the present inventors have actually developed a spectrometer capable of performing measurement while holding the sample horizontally, and confirmed that accurate measurement can be performed by performing measurement with the device. . Hereinafter, a spectrometer of the present invention including a mechanism for holding a sample horizontally will be described.
[0009]
FIG. 1 is a schematic configuration diagram of the spectrometer of the present invention. 1 includes a light irradiation unit 12 (light source 26, spectroscope 28), an optical path changing unit (total reflection prism 16), and a polarization modulation unit 14 (polarizer 30, photoelastic modulator (PEM)). 32), a rotating sample stage 18, an analyzer 20, and a photodetector 22.
Here, the light irradiation unit 12 includes a light source 26 and a spectroscope 28 for performing wavelength scanning. The light emitted from the light source 26 is converted into monochromatic light having a predetermined wavelength by the spectroscope 28. The optical path changing unit uses the total reflection prism 16 to change the traveling direction of light from the horizontal direction to the vertical direction.
[0010]
In this embodiment, the polarization modulator 14 uses the polarizer 30 and the PEM 32. The light from the light irradiating unit 12 is linearly polarized by the polarizer 30 in a predetermined angle direction (for example, 45 °) with respect to the axis direction of the PEM 32. By passing this linearly polarized light through the PEM 32, a phase difference is given between the two polarized light components (between mutually perpendicular polarized light components), and the polarization state of light is modulated. Further, a voltage having a predetermined frequency is applied to the PEM 32, and the above-described phase difference is modulated according to the frequency, and the polarization state having the predetermined modulation frequency is modulated.
[0011]
At the center of the rotating sample stage 18 for mounting the sample 24, a through-hole 38 is provided that penetrates in the thickness direction. Light passing from the sample 24 passes through the through hole 38 and travels toward the analyzer 20. The rotating sample stage 18 is configured to be rotatable in a horizontal plane about a central axis of the through hole 38. For example, a motor that can control the rotation angle such as a stepping motor may be configured to rotate at an arbitrary angle and stop. As a result of this configuration, measurement can be performed with the sample 24 placed at an arbitrary coordination angle.
[0012]
The analyzer 20 is also configured to be rotatable, and its coordination axis can be changed. Further, the analyzer 20 is configured to be movable so as to be detachable / insertable from the optical path. That is, the transmitted light from the sample can be detected through or not through the analyzer 20, and may be selected according to the property of the sample to be measured.
As the photodetector 22, for example, a photomultiplier tube may be used. The light detector 22 detects passing light from the sample 24.
The light irradiating section 12 and the photodetector 22 as the measuring means 36 have a horizontal arrangement similar to that of a normal spectrometer. That is, in the present invention, by providing the optical path changing unit, the light emitted in the horizontal direction is changed to the vertical direction, and the observation of the sample from the vertical direction is enabled.
[0013]
Next, the operation of the spectrometer of the present invention will be described. The light emitted from the light source 26 passes through the spectroscope 28 as described above and is converted into monochromatic light. This monochromatic light is emitted in the horizontal direction, is totally reflected by the total reflection prism 16, and the course is changed from the horizontal direction to the vertical direction. The light traveling in the vertical direction is light whose polarization state is modulated by the polarizer 30 and the PEM 32. The light whose polarization state has been modulated is applied to the sample 24 on the rotating sample stage 18, and the transmitted light from the sample 24 passes through the through hole 38 of the rotating sample stage 18 toward the analyzer 20. The light that has passed through the analyzer 20 is sent to a photodetector 22 by a mirror, an optical fiber, or the like, and is detected.
[0014]
The detection signal from the photodetector 22 is subjected to signal processing by a signal processing device (not shown). Various optical information of the sample (circular dichroism, light dispersion, linear dichroism, linear birefringence) based on the same frequency component as the polarization modulation frequency and twice the high frequency component of the detection signal Is required. The spectrum of the optical information can be obtained by changing the wavelength of the monochromatic light from the spectroscope and performing the measurement. The specific procedure of these measurements may be performed in the same manner as in the related art (for details, see, for example, Patent Documents 1 to 4).
[0015]
As described above, the conventional spectrometer has a configuration in which light is irradiated in the horizontal direction due to the space of a spectroscope or the like. However, in the present invention, the arrangement of the light source, the spectroscope, the photodetector, and the like is the same as that of the related art. As a result, the sample can be held horizontally, and the sample can be measured from the vertical direction. That is, according to the spectrometer of the present invention, accurate spectrometry can be performed on a sample that is easily affected by a gravitational field, for example, a gel sample, a protein such as β-amyloid or BSA, or the like. It is.
[0016]
The polarization modulator 14, the total reflection prism 16, the rotating sample table 18, and the analyzer 20 are installed in a sample chamber 34. Since the sample chamber 34 has an independent configuration, the sample chamber 34 can be mounted as an option on a normal spectrometer (corresponding to the measuring means 36) and used.
The optical path changing unit may change the optical path using not only the total reflection prism used in the present embodiment but also a mirror or an optical fiber.
It is also possible to use a Faraday cell as the polarization modulator, periodically modulate the plane of polarization of linearly polarized light, and measure the optical rotation of the sample by the optical null method.
[0017]
FIG. 2 shows another embodiment of the spectrometer according to the present invention. The parts corresponding to those in FIG.
In the spectrometer 110 of FIG. 2, the polarizer 130 of the polarization modulator 114 is installed at the measurement unit 136, and the PEM 132 is installed in the sample chamber 134. Even in this case, the polarization modulation of light is performed after bending in the vertical direction. That is, the polarizer 130 may be installed before the optical path changing unit (total reflection prism 116), and the PEM 132 may be installed after the optical path changing unit. The measurement procedure and the like may be performed in the same manner as in FIG.
[0018]
【The invention's effect】
According to the spectrometer of the present invention, the sample can be held horizontally by providing the optical path changing unit for bending the light in the horizontal direction in the vertical direction, and the sample is greatly affected by the gravitational field. In addition, accurate measurements can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a spectrometer of the present invention.
FIG. 2 shows an embodiment of the spectrometer of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Spectrometer 12 Light irradiation part 14 Polarization modulation part 16 Total reflection prism 18 Rotating sample stand 20 Analyzer 22 Light detection part 24 Sample

Claims (3)

A light irradiation unit that emits monochromatic light having a wavelength selected from a plurality of wavelengths to perform wavelength scanning,
An optical path changing unit that changes a path of light emitted from the light irradiation unit,
A polarization modulator for periodically modulating the polarization state of light whose path has been changed by the optical path changing unit,
A rotating sample stage rotatable in a horizontal plane around the optical axis,
A light detector for detecting transmitted light transmitted through the sample on the rotating sample stage;
Light is irradiated in the horizontal direction from the light irradiation unit, the light traveling in the horizontal direction is changed the traveling direction of the light in the vertical direction by the optical path changing unit, was installed horizontally on the rotating sample stage A spectrometer for irradiating a sample with light in a vertical direction. The spectrometer according to claim 1,
The spectrometer is characterized in that the optical path changing unit is constituted by a total reflection prism or a mirror, and reflects light traveling in a horizontal direction by the total reflection prism or a mirror to change the traveling direction to a vertical direction. The spectrometer according to claim 1 or 2,
By irradiating the sample with the light whose polarization state is modulated, and measuring the transmitted light from the sample, the circular dichroism or optical rotation dispersion or the linear dichroism or the linear birefringence of the sample is measured. Spectrometer.

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