JP2009133850A - Polarization modulator and measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring apparatus and a measuring method, capable of precisely measuring an optical rotation of an object to be measured without affected by the ambient temperature, and making the apparatus compact. <P>SOLUTION: The measuring apparatus 1 which measures the optical rotation of the object to be measured, comprises: a first polarizer 18 for transmitting a prescribed polarized component of light; a polarization modulator 20 for modulating the transmitted light into arbitrary polarized light; a second polarizer 32 for transmitting a prescribed polarized component of the light being polarization-modulated and transmitted through the object to be measured 30; and a detecting section 34 for detecting the transmitted light and converting it into an electric signal. The polarization modulator 20 comprises: a liquid crystal element 21 composed of a first liquid crystal cell 22 and a second liquid crystal cell 24; a temperature control section 26 for controlling a temperature of the liquid crystal cell 21; and voltage controlling sections 23, 25 for controlling voltages being applied to the first liquid crystal cell 22 and the second liquid crystal cell 24. The first liquid crystal cell 22 and the second liquid crystal cell 24 are made different from each other in rubbing direction, whereby their primary-axis azimuths are different from each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarization modulator used in a measurement device that measures the optical rotation of a measurement target, and a measurement device that measures the optical rotation of a measurement target.

2. Description of the Related Art Conventionally, an optical rotation measuring device for measuring the optical rotation and concentration of a substance having optical activity such as sugars and amino acids is known. As a typical optical rotation measuring device, devices using a rotating polarizer method or a Faraday modulation method are known. However, these methods have a problem that the apparatus becomes large due to the need for mechanical drive, and a problem that a high voltage is required. As an optical rotation measuring apparatus for solving these problems, there is an apparatus using a polarization modulator that modulates linearly polarized light incident on a sample using two liquid crystal elements whose principal axis directions are shifted. As such a technique, for example, there is a conventional technique disclosed in Japanese Patent Application Laid-Open No. 2007-93289.
JP 2007-93289 A

  However, in the conventional optical rotation measuring device, in order to shift the principal axis directions of the two liquid crystal elements by a predetermined angle, it is necessary to adjust one of the two liquid crystal elements to be inclined at a predetermined angle. The liquid crystal element cannot be integrated, and there is a problem that the usability is poor. In addition, since the two liquid crystal elements cannot be integrated, it is necessary to provide temperature control means for controlling the temperature of the two liquid crystal elements for each liquid crystal element, which increases the size of the apparatus. there were.

  The present invention has been made in view of the problems as described above, and the object of the present invention is that adjustment of the principal axis direction of the liquid crystal element is unnecessary, and the measurement target can be accurately measured without being affected by the environmental temperature. An object of the present invention is to provide a measuring apparatus capable of measuring the optical rotation and miniaturizing the apparatus, and a polarization modulator used in the measuring apparatus.

(1) The present invention provides a first polarizer that transmits a predetermined polarization component of light including a predetermined band component, and a polarization modulator that modulates light transmitted through the first polarizer into arbitrary polarization. A second polarizer that transmits a predetermined polarization component of the light that has passed through the measurement object via the polarization modulator, and a detector that detects the light transmitted through the second polarizer and converts it into an electrical signal The polarization modulator used in a measuring device for measuring the optical rotation of the measurement object,
A liquid crystal element composed of a first parallel alignment liquid crystal cell and a second parallel alignment liquid crystal cell;
A temperature control unit for controlling the temperature of the liquid crystal element;
A voltage controller for controlling an applied voltage to the first parallel alignment liquid crystal cell and the second parallel alignment liquid crystal cell,
The first parallel-aligned liquid crystal cell and the second parallel-aligned liquid crystal cell are characterized in that main axis directions are different from each other due to different rubbing directions.

  In the present invention, the rubbing direction refers to the direction of rubbing treatment for aligning liquid crystals, and the rubbing treatment may be a treatment for rubbing the alignment film with a rubbing cloth, or a treatment for irradiating the alignment film with high energy light. .

  According to the present invention, the principal axis orientation in which one of the first and second parallel alignment liquid crystal cells is inclined at a predetermined angle by making the rubbing directions of the first and second parallel alignment liquid crystal cells different from each other. Therefore, the first and second parallel alignment liquid crystal cells can be overlapped and integrated in parallel. The apparatus can be miniaturized by configuring the polarization modulator with one liquid crystal element formed by integrating the first and second parallel alignment liquid crystal cells.

  Further, according to the present invention, by controlling the temperature of the liquid crystal element using the temperature control unit, it is possible to prevent an error (fluctuation) from occurring in the birefringence phase difference with respect to the same applied voltage due to a change in the environmental temperature. it can. Further, by controlling the temperature of one liquid crystal element composed of the first and second parallel alignment liquid crystal cells using the temperature control unit, the one liquid crystal element and the temperature control unit are integrated. Therefore, the apparatus can be reduced in size as compared with the case where the temperature control unit is provided for each of the first and second parallel alignment liquid crystal cells.

(2) In the polarization modulator according to the present invention,
The first parallel alignment liquid crystal cell has a main axis direction inclined by an odd multiple of 45 ° with respect to the main axis direction of the first polarizer,
The second parallel alignment liquid crystal cell has a main axis direction inclined at an even multiple of 45 ° with respect to the main axis direction of the first polarizer.

  According to the present invention, the principal axis directions of two parallel alignment liquid crystal cells can be shifted from each other by 45 ° without tilting one of the first and second parallel alignment liquid crystal cells.

(3) In the polarization modulator according to the present invention,
The temperature controller is
It includes a temperature sensor provided on the substrate of the liquid crystal element.

  According to the present invention, the temperature of the liquid crystal element can be accurately controlled.

(4) Moreover, this invention is a measuring device which measures the optical rotation of a measuring object,
A first polarizer that transmits a predetermined polarization component of light including a predetermined band component;
A polarization modulation unit that modulates light transmitted through the first polarizer into arbitrary polarization;
A second polarizer that transmits a predetermined polarization component of the light transmitted through the measurement object via the polarization modulator;
A detector that detects the light transmitted through the second polarizer and converts it into an electrical signal;
The polarization modulator is
A liquid crystal element composed of a first parallel alignment liquid crystal cell and a second parallel alignment liquid crystal cell, a temperature control unit for controlling the temperature of the liquid crystal element, the first parallel alignment liquid crystal cell and the second parallel alignment A voltage control unit for controlling the voltage applied to the alignment liquid crystal cell,
The first parallel-aligned liquid crystal cell and the second parallel-aligned liquid crystal cell are characterized in that main axis directions are different from each other due to different rubbing directions.

  ADVANTAGE OF THE INVENTION According to this invention, adjustment of the principal axis direction of a liquid crystal element is unnecessary, it is possible to measure the optical rotation of a measuring object accurately without being influenced by the environmental temperature, and the size of the apparatus can be reduced. An apparatus can be provided.

(5) In the measuring device according to the present invention,
It further includes an arithmetic processing unit that performs arithmetic processing for calculating the optical rotation of the measurement object based on the light intensity detected by the detection unit.

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Configuration of Measuring Device FIG. 1 is a block diagram for explaining the configuration of the measuring device of the present embodiment. The measuring device 1 is a device that measures the optical rotation of a sample 100 that is a measurement target. The measuring device 1 includes an optical system 10 and a control device 40. The control device 40 includes an arithmetic processing unit 50, which performs arithmetic processing for calculating the optical rotation of the sample 100 based on the optical elements included in the optical system 10 and the light intensity of light transmitted through the sample 100. Hereinafter, the device configuration of the measuring device 1 will be described.

1-1. Optical system 10
The optical system 10 includes a light source 12 and a detection unit 34. The optical system 10 includes a collimator lens 13, a mirror 14, an interference filter 16, an analyzer 18 (first polarizer) provided on an optical path L connecting the light source 12 and the detection unit 34 via the mirror 14. A polarization modulator 20 (polarization modulator) and an analyzer 32 (second polarizer) are included. These optical elements convert the light emitted from the light source 12 through the collimating lens 13, the interference filter 16, the analyzer 18 (first polarizer), the first liquid crystal cell 22, and the polarization modulator 20. The light transmitted through the sample 30 and incident on the detection unit 34 via the analyzer 18 is arranged. Each will be described below.

  The light source 12 is a white light source such as a tungsten halogen lamp, and emits white light including a wide range of wavelength components.

  The collimating lens 13 converts white light from the light source 12 guided by the optical fiber into parallel light. The mirror 14 reflects this parallel light and makes it incident on the interference filter 16.

  The interference filter 16 transmits a predetermined wavelength component of the parallel light reflected by the mirror 14. The interference filter 16 of the present embodiment transmits light having a center wavelength of 589 nm.

  The polarizer 18 is an incident-side polarizer that makes light transmitted through the interference filter 16 linearly polarized light. That is, the polarizer 18 transmits linearly polarized light having a polarization plane in the direction of the transmission axis (main axis direction). The polarizer 18 of this embodiment is installed so that the principal axis direction is 0 ° in the horizontal direction.

The polarization modulator 20 modulates the linearly polarized light transmitted through the polarizer 18 into arbitrary polarized light. The polarization modulation unit 20 includes a liquid crystal element 21 including a first liquid crystal cell 22 (first parallel alignment liquid crystal cell) and a second liquid crystal cell 24 (second parallel alignment liquid crystal cell), and first and first liquid crystal cells. The first and second voltage control units 23 control the voltages applied to the two liquid crystal cells 22 and 24 and change the birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24, respectively. , 25 and a temperature control unit 26 for controlling the temperature of the liquid crystal element 21.

  The first liquid crystal cell 22 installed in front of the light advance direction has a main axis in a direction rotated 45 ° counterclockwise toward the light advance direction with respect to the main axis direction (horizontal 0 °) of the polarizer 18. Further, the second liquid crystal cell 24 installed on the back side in the light traveling direction has a main axis parallel to the main axis direction (horizontal 0 °) of the polarizer 18. Accordingly, the principal axis directions of the first and second liquid crystal cells 22 and 24 are deviated from each other by 45 °.

As described above, the phase modulation is performed using the two liquid crystal cells 22 and 24 whose principal axis directions are 45 ° and 0 °, respectively, and the birefringence phase differences δ ₁ and δ ₂ are variable. The transmitted predetermined linearly polarized light can be changed to arbitrary linearly polarized light, elliptically polarized light or circularly polarized light.

  FIGS. 2A, 3 </ b> A, and 3 </ b> B are diagrams schematically illustrating the liquid crystal element 21 including the first and second liquid crystal cells 22 and 24 of the present embodiment. . FIG. 2A is a top view of the liquid crystal element 21.

  As shown in FIG. 2A, each of the first and second liquid crystal cells 22 and 24 includes two transparent substrates TS, a transparent electrode EL provided on the inner surface of the transparent substrate TS, and two transparent substrates. It is constituted by nematic liquid crystal LC sealed between the substrates TS. An alignment film AL1 is provided at the interface between the transparent substrate TS and the nematic liquid crystal LC in the first liquid crystal cell 22, and an alignment film AL2 is provided at the interface between the transparent substrate TS in the second liquid crystal cell 24 and the nematic liquid crystal LC. It has been. The two liquid crystal cells 22 and 24 are overlapped on the transparent substrate TS to constitute one liquid crystal element 21. Here, the transparent substrate TS where the two liquid crystal cells are overlapped may be one, and the transparent substrate TS constituting the liquid crystal element 21 may be three as shown in FIG. 2B. . At this time, the transparent electrode EL and the alignment film AL are provided on both surfaces of the central transparent substrate TS.

  3A is a front view of the liquid crystal element 21 (front view of the first liquid crystal cell 22), and FIG. 3B is a rear view of the liquid crystal element 21 (front view of the second liquid crystal cell 24). ).

  As shown in FIG. 3A, in the first liquid crystal cell 22, the rubbing direction (alignment direction) RD is 45 ° with respect to the reference direction HD, and the main axis direction of birefringence is thus 45 °. It has become. Further, as shown in FIG. 3B, the second liquid crystal cell 24 has a rubbing direction (alignment direction) RD of 0 ° with respect to the reference direction HD, whereby the main axis direction of birefringence is also 0 °. It has become. That is, the rubbing treatment direction applied to the alignment film AL1 (see FIG. 2A) of the first liquid crystal cell 22 is 45 ° with respect to the reference direction HD, and the alignment film of the second liquid crystal cell 24 The rubbing process applied to AL2 (see FIG. 2A) is 0 ° with respect to the reference direction HD. In the second liquid crystal cell 24, the rubbing direction RD may be 90 ° with respect to the reference direction HD. The reference direction HD is the same direction as the main axis direction (horizontal 0 °) of the polarizer 18.

  Thus, by setting the rubbing directions of the first and second liquid crystal cells 22 and 24 to 45 ° and 0 ° (or 90 °), respectively, one of the first and second liquid crystal cells 22 and 24 is The principal axis directions of the two liquid crystal cells 22 and 24 can be shifted from each other by 45 ° without being inclined at 45 ° with respect to the other. Therefore, the first and second liquid crystal cells 22 and 24 can be overlapped and integrated in parallel. And the apparatus can be reduced in size by comprising the polarization modulation part 20 with the liquid crystal element 21 which comprised the 1st and 2nd liquid crystal cells 22 and 24 integrally.

  FIG. 4 is a diagram schematically illustrating the polarization modulator 20 (polarization modulator) of the present embodiment.

  The polarization modulation unit 20 includes a temperature control unit 26 that controls the temperature of the liquid crystal element 21. The temperature control unit 26 includes a copper case CC, a temperature sensor TH, a Peltier element PD, a heat sink HS, and a cooling fan CF, and the temperature of the liquid crystal element 21 formed by integrating the first and second liquid crystal cells 22 and 24. Is controlled to be constant. The liquid crystal element 21 is housed in a copper case CC using copper having excellent heat conduction. A temperature sensor TH such as a thermistor for detecting the temperature of the copper case CC and a Peltier element PD (thermoelectric element) for cooling (heat absorption) or heating the copper case CC are provided at a position in contact with the copper case CC. A heat sink HS (heat radiating plate) for dissipating the heat of the Peltier element PD is provided at a position in contact with the Peltier element PD, and a cooling fan CF is attached below the heat sink HS to supplement the heat diffusion capability of the heat sink HS. It has been. The copper case CC is provided with an opening OM through which incident light to the liquid crystal element 21 passes and an opening OM (not shown) through which light emitted from the liquid crystal element 21 passes, and the Peltier element PD and the heat sink HS are provided with , Each has an opening OM through which incident light to the liquid crystal element passes.

  As shown in FIG. 4, by controlling the temperature of the liquid crystal element 21 to be constant by using the temperature control unit 26 including the copper case CC, the temperature sensor TH, the Peltier element PD, the heat sink HS, and the cooling fan CF, It is possible to prevent an error (fluctuation) from occurring in the birefringence phase difference of the first and second liquid crystal cells 22 and 24 with respect to the same applied voltage due to a change in environmental temperature. Further, by using the temperature control unit 26 to control the temperature of the liquid crystal element 21 formed by integrating the first and second liquid crystal cells 22 and 24, the liquid crystal element 21 and the temperature control unit 26 can be controlled. The device can be configured in an integrated manner, and the apparatus can be downsized as compared with the case where a temperature control unit is provided for each of two liquid crystal cells that are not integrated (the temperature of each liquid crystal cell is individually controlled). .

  FIG. 5 is a diagram showing the temperatures of the first and second liquid crystal cells 22 and 24 when the environmental temperature is changed from 20 ° C. to 35 ° C. using a thermostatic bath. In FIG. 5, the horizontal axis indicates the environmental temperature, and the vertical axis indicates the temperature of the first and second liquid crystal cells 22 and 24. Referring to FIG. 5, it can be seen that the temperatures of the two liquid crystal cells 22 and 24 are kept constant with respect to changes in the environmental temperature. At this time, the temperature change amounts of the first and second liquid crystal cells 22 and 24 were within 0.1 ° C., respectively. Therefore, it was found that the polarization modulator 20 of the present embodiment can control the temperature of the first and second liquid crystal cells 22 and 24 to be constant without being affected by the environmental temperature. Note that the temperature of the liquid crystal element 21 is preferably controlled to be constant at a temperature higher than the environmental temperature in order to prevent condensation.

  Referring again to FIG. 1, the analyzer 32 is an output-side polarizer that uses light that has passed through the sample 30 as linearly polarized light. That is, the analyzer 32 transmits linearly polarized light having a polarization plane in the direction of the transmission axis (main axis direction). The polarizer 32 of this embodiment is installed so that the principal axis direction is horizontal 45 °.

  The detection part 34 consists of photoelectric sensors, for example, detects the light intensity of the emitted light from the analyzer 32, converts it into a voltage, and outputs it as light intensity information.

1-2. Control device 40
The control device 40 includes an arithmetic treatment unit 50, a control signal generation unit 60, and a storage unit 70.

  The arithmetic processing unit 50 performs arithmetic processing for calculating the optical rotation of the sample 30 based on the light intensity information output from the detection unit 34.

The control signal generation unit 60 generates a control signal to control the first and second voltage control units 23 and 25 (liquid crystal drivers of the liquid crystal cells of the first and second liquid crystal cells 22 and 24), The birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24 are changed.

  Further, the control signal generation unit 60 controls the operation of the temperature control unit 26. For example, a control signal is generated based on the output from the temperature sensor TH shown in FIG. 4 to control the operation of the Peltier element PD or the cooling fan CF shown in FIG.

The storage unit 50 has a function of temporarily storing various data. For example, the light intensity information output from the detection unit 34 is used as the birefringence phase differences δ ₁ , δ of the first and second liquid crystal cells 22, 24. ₂ and stored in association with each other.

2. Optical rotation measurement principle Next, the optical rotation measurement principle employed by the measurement apparatus of the present embodiment will be described.

2-1. Theoretical expression of the light intensity of the light detected by the detection unit 34 When the Stokes parameter of the monochromatic light incident on the polarizer 18 is S _in and the Stokes parameter of the light transmitted through the sample 30 and emitted from the analyzer 32 is S ′. , S ′ can be expressed by the following equation.

なお、Ｉ_０は偏光子１８に入射する単色光の光強度である。またＰ_０°は、主軸方位が０°である偏光子１８のミュラー行列である。またＲ_{δ１，４５°}は、主軸方位が４５°であり複屈折位相差がδ_１である第１の液晶セル２２のミュラー行列である。またＲ_{δ２，０°}は、主軸方位が０°であり複屈折位相差がδ_２である第２の液晶セル２４のミュラー行列である。またＴ_φは旋光度がφである試料３０のミュラー行列である。またＡ_４５°は、主軸方位が４５°である検光子３２のミュラー行列である。

Note that I ₀ is the light intensity of monochromatic light incident on the polarizer 18. P _{0 °} is a Mueller matrix of the polarizer 18 whose principal axis direction is 0 °. The _R δ1,45 _° is the Mueller matrix of the first liquid crystal cell 22 birefringence phase difference is the principal axis direction is 45 ° is [delta] _1. The _R δ2,0 _° is the Mueller matrix of the second liquid crystal cell 24 the principal axis direction is ₂ birefringent phase difference δ is 0 °. _Tφ is the Mueller matrix of the sample 30 whose optical rotation is φ. A _{45 °} is a Mueller matrix of the analyzer 32 whose principal axis orientation is 45 °.

Here, assuming that the light intensity of the light detected by the detection unit 34 is I (δ ₁ , δ ₂ , φ), the I (δ ₁ , δ ₂ , φ) is a Stokes parameter of the light emitted from the analyzer 32. Since S ₀ ′, from equation (1),

となる。

It becomes.

2-2. Calculation principle of the optical rotation of the sample 30 The optical rotation of the sample 30 is obtained as follows by measuring the light intensity of the light passing through the sample 30 and the analyzer 32 while changing the polarization state of the light incident on the sample 30. .

For example, the birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24 are set as δ ₁ = δ and δ ₂ = δ + π / 2, and δ is continuously from 0 ° to 360 °. Change. At this time, assuming that the light intensity detected by the detection unit 34 is I (δ, δ + π / 2, φ), the I (δ, δ + π / 2, φ) is obtained from the equation (2):

となる。ここでａ（＝Ｉ_０／４ｓｉｎ２φ）及びｂ（＝Ｉ_０／８ｃｏｓ２φ）は、それぞれフーリエ関数ｃｏｓδ及びｓｉｎ２δの係数を示す。式（３）からδを連続的に０°〜３６０°の範囲で変調させると、光強度Ｉ（δ，δ＋π／２，φ）が周期的に変化することがわかる。従って検出部３４が検出する光強度Ｉ（δ，δ＋π／２，φ）の周期的変化をフーリエ解析し、係数ａ、ｂを求めることにより試料３０の旋光度φは、

It becomes. Where _a (= I 0 / _4sin2φ) and _b (= I 0 / _8cos2φ) indicate respectively the coefficients of the Fourier function cosδ and Sin2deruta. From equation (3), it can be seen that when δ is continuously modulated in the range of 0 ° to 360 °, the light intensity I (δ, δ + π / 2, φ) changes periodically. Therefore, the optical rotation φ of the sample 30 is obtained by performing Fourier analysis on the periodic change of the light intensity I (δ, δ + π / 2, φ) detected by the detector 34 and obtaining the coefficients a and b.

により算出することができる。

Can be calculated.

The birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24 are modulated four times, 0, π / 2, π, and 3π / 2, respectively, and the detection unit 34 detects at this time. From the four light intensity values, the optical rotation φ of the sample 30 is

により算出することができる。ここでＩ_１は、第１及び第２の液晶セル２２、２４の複屈折位相差δ_１、δ_２を０に設定したときの検出部３４が検出する光強度である。またＩ_２は、複屈折位相差δ_１、δ_２をπ／２に設定したときの検出部３４が検出する光強度である。またＩ_３は、複屈折位相差δ_１、δ_２をπに設定したときの検出部３４が検出する光強度である。またＩ_４は、複屈折位相差δ_１、δ_２を３π／２に設定したときの検出部３４が検出する光強度である。この手法（位相変調法）によれば、第１及び第２の液晶セル２２、２４の複屈折位相差δ_１、δ_２を４回変調するだけでよいため、旋光度φを高速に算出することが可能となる
３．測定結果
図６、図７に、本実施形態の計測装置の計測結果を示す。

Can be calculated. Here, I ₁ is the light intensity detected by the detector 34 when the birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24 are set to 0. I ₂ is the light intensity detected by the detector 34 when the birefringence phase differences δ ₁ and δ ₂ are set to π / 2. I ₃ is the light intensity detected by the detector 34 when the birefringence phase differences δ ₁ and δ ₂ are set to π. I ₄ is the light intensity detected by the detector 34 when the birefringence phase differences δ ₁ and δ ₂ are set to 3π / 2. According to this method (phase modulation method), since the birefringence phase differences δ ₁ and δ ₂ of the first and second liquid crystal cells 22 and 24 need only be modulated four times, the optical rotation φ is calculated at high speed. 2. It becomes possible. Measurement Results FIG. 6 and FIG. 7 show the measurement results of the measurement apparatus of this embodiment.

  FIG. 6 shows the result of measuring the optical rotation (optical rotation angle) by changing the environmental temperature. Here, a measuring device (optical system) is installed in the thermostat, the temperature is changed from 26 ° C. to 34 ° C. at intervals of 1 ° C., and the crystal standard optical rotator (the optical rotation 34.11) which is the sample 30 at each temperature. The temperature and the optical rotation were measured. The calculation of the optical rotation was performed by Fourier analysis of 32-point sampling. In FIG. 6, the horizontal axis indicates the temperature of the crystal, and the vertical axis indicates the measured optical rotation. As shown by the solid line in FIG. 6, the optical rotation of the used quartz sample changes linearly with respect to temperature.

  In FIG. 6, black dots indicate measurement results obtained by Fourier analysis. The optical rotation measured by Fourier analysis was approximately equal to the optical rotation indicated by the solid line, and the measurement accuracy was 0.0004 °. Therefore, it can be seen that the optical rotation of the crystal can be accurately measured by the measurement apparatus of the present embodiment without being affected by the environmental temperature.

  FIG. 7 shows the result of measuring the optical rotation by changing the concentration of the aqueous solution of the optical rotatory substance. For sample 30, sucrose having a specific rotation of 60.3 ° and ascorbic acid having a specific rotation of 20.7 ° were used. In FIG. 7, the horizontal axis represents the concentration of the aqueous solution, and the vertical axis represents the measured optical rotation.

  In FIG. 7, the white dots indicate the measurement results for sucrose, and the black dots indicate the measurement results for ascorbic acid. The solid line shows the theoretical value of sucrose, and the broken line shows the theoretical value of ascorbic acid. The measurement results for sucrose and ascorbic acid are almost equal to the theoretical values. Therefore, it can be seen that the optical rotation and concentration of the optical rotatory substance can be measured with high accuracy by the measuring apparatus of this embodiment.

4). Modifications The present invention is not limited to the above-described embodiment, and various modifications can be made. The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

  For example, in this embodiment, the case where the temperature sensor TH such as a thermistor provided at a position in contact with the copper case CC is used as an example of the temperature sensor included in the temperature control unit 26 that controls the temperature of the liquid crystal element 21 ( As shown in FIG. 4, a thermocouple provided on the substrate of the liquid crystal element 21 may be used as a temperature sensor included in the temperature control unit 26.

  In the example shown in FIG. 8A, a thermocouple TC (thin film thermocouple) is provided on the transparent substrate TS of the first liquid crystal cell 22 constituting the liquid crystal element 21. A thermocouple is a temperature sensor that joins two types of metals with different thermoelectric power. Utilizing the phenomenon (Seebeck effect) in which current flows in a certain direction when two junction points are set to different temperatures, causing thermoelectromotive force. Temperature sensor.

  FIG. 8B is a perspective view of the thermocouple TC provided on the transparent substrate TS. As shown in FIG. 8B, the thermocouple TC can be formed by patterning two types of metal layers (metal A and metal B) on the transparent substrate TS by a vacuum deposition method. For example, copper and constantan can be used as the two kinds of metals. Further, the lead wire (compensation lead wire) of the thermocouple TC is attached to the attachment position IP on the thermocouple TC.

  FIG. 8C is a cross-sectional view taken along line AA in FIG. As shown in FIG. 8C, an insulating layer IL (sealant) is formed between the thermocouple TC and the electrode EL so that the current flowing through the electrode EL does not affect the thermocouple TC. Yes.

  When the thermocouple TC is used as the temperature sensor included in the temperature control unit 26, the control signal generation unit 60 shown in FIG. 1 operates the Peltier element PD or the cooling fan CF shown in FIG. 4 based on the output from the thermocouple TC. And the temperature of the liquid crystal element 21 is controlled to be constant.

  As described above, by using the thermocouple TC provided on the transparent substrate TS of the liquid crystal cell constituting the liquid crystal element 21 as the temperature sensor included in the temperature control unit 26 that controls the temperature of the liquid crystal element 21, FIG. The temperature of the liquid crystal element 21 can be measured more accurately and the temperature of the liquid crystal element 21 can be controlled more accurately than in the case where the temperature sensor TH provided at a position in contact with the copper case CC shown is used. .

  In the example of FIG. 8A, the case where the thermocouple TC is provided on the transparent substrate TS of the first liquid crystal cell 22 has been described. However, the thermocouple TC may be provided on the transparent substrate TS of the second liquid crystal cell 24. Good. Two thermocouples TC may be provided on the transparent substrate TS of the first liquid crystal cell 22 and on the transparent substrate TS of the second liquid crystal cell 24, respectively. In this case, the control signal generator 60 controls the operation of the Peltier element PD or the cooling fan CF based on the outputs from the two thermocouples TC (for example, the average value of the output values from the two thermocouples TC).

  It can be used not only for measuring the concentration of soft drinks and fruits, but also for analyzing molecular structures such as proteins, amino acids, and nucleic acids, and for quality control of chemicals. Moreover, it can utilize as a blood glucose level sensor which measures a blood glucose level.

The block diagram for demonstrating the structure of the measuring device of this embodiment. The figure which shows typically the liquid crystal element comprised from the 1st and 2nd liquid crystal cell of this embodiment. The figure which shows typically the liquid crystal element comprised from the 1st and 2nd liquid crystal cell of this embodiment. The figure which shows typically the polarization modulation part of this embodiment. The figure which shows the verification result of temperature control. The figure which shows the measurement result by the measuring device of this embodiment. The figure which shows the measurement result by the measuring device of this embodiment. The figure for demonstrating a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 10 Optical system 12 Light source 13 Collimating lens 14 Mirror 16 Interference filter 18 Polarizer 20 Polarization modulation part (polarization modulator)
21 liquid crystal element 22 first liquid crystal cell 23 first voltage control unit 24 second liquid crystal cell 25 second voltage control unit 26 temperature control unit 30 sample 32 analyzer 34 detection unit 40 control device 50 arithmetic processing unit 60 control Signal generator 70 Storage unit

Claims (5)

A first polarizer that transmits a predetermined polarization component of light including a predetermined band component, a polarization modulator that modulates light transmitted through the first polarizer into an arbitrary polarization, and the polarization modulator. A second polarizer that transmits a predetermined polarization component of the light transmitted through the measurement object, and a detection unit that detects the light transmitted through the second polarizer and converts it into an electrical signal, The polarization modulator used in a measuring device for measuring the optical rotation of
A liquid crystal element composed of a first parallel alignment liquid crystal cell and a second parallel alignment liquid crystal cell;
A temperature control unit for controlling the temperature of the liquid crystal element;
A voltage controller for controlling an applied voltage to the first parallel alignment liquid crystal cell and the second parallel alignment liquid crystal cell,
The polarization modulator according to claim 1, wherein the first parallel alignment liquid crystal cell and the second parallel alignment liquid crystal cell have different main axis directions due to different rubbing directions. In claim 1,
The first parallel alignment liquid crystal cell has a main axis direction inclined by an odd multiple of 45 ° with respect to the main axis direction of the first polarizer,
The polarization modulator according to claim 1, wherein the second parallel alignment liquid crystal cell has a main axis direction inclined at an even multiple of 45 ° with respect to the main axis direction of the first polarizer. In claim 1 or 2,
The temperature controller is
A polarization modulator comprising a temperature sensor provided on a substrate of the liquid crystal element. A measuring device for measuring the optical rotation of a measurement object,
A first polarizer that transmits a predetermined polarization component of light including a predetermined band component;
A polarization modulation unit that modulates light transmitted through the first polarizer into arbitrary polarization;
A second polarizer that transmits a predetermined polarization component of the light transmitted through the measurement object via the polarization modulator;
A detector that detects the light transmitted through the second polarizer and converts it into an electrical signal;
The polarization modulator is
A liquid crystal element composed of a first parallel alignment liquid crystal cell and a second parallel alignment liquid crystal cell, a temperature control unit for controlling the temperature of the liquid crystal element, the first parallel alignment liquid crystal cell and the second parallel alignment A voltage control unit for controlling the voltage applied to the alignment liquid crystal cell,
The measuring apparatus according to claim 1, wherein the first parallel alignment liquid crystal cell and the second parallel alignment liquid crystal cell have different principal axis directions due to different rubbing directions. In claim 4,
The measurement apparatus further comprising: an arithmetic processing unit that performs arithmetic processing for calculating the optical rotation of the measurement object based on the light intensity detected by the detection unit.

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