JP4343743B2 - Optical rotation measuring device and concentration measuring device - Google Patents

Description

  The present invention relates to an optical rotation measuring device and a concentration measuring device, and more particularly to a technique for measuring the concentration of an optical rotatory substance contained in a sample stably and with high accuracy.

  As a means for measuring the concentration of an optical rotatory substance in a sample, an optical method for determining the concentration by measuring the optical rotation is considered useful. For example, as a method for measuring glucose concentration, an enzyme method using an enzyme such as GOD method is known. However, in this method, an electrode needs to be brought into contact with a sample. Since the number of times of measurement is limited, it is necessary to perform maintenance such as maintenance every certain period, replacement of part of the apparatus, addition of buffer solution, and the like. In this respect, in an optical method such as optical rotation measurement, measurement can be performed without touching the sample directly, so that measurement can be performed for a long period without particularly requiring maintenance.

The principle of the method for obtaining the concentration of the optically rotatory substance in the sample from the optical rotation is based on Equation 1.
θ (λ) = α (λ) · c · L (Formula 1)
Here, θ (λ) is the optical rotation when the wavelength of the light beam is λ, α (λ) is the specific rotation of the optical rotatory material when the wavelength of the light beam is λ, and c is the optical rotation material in the sample. , L is the optical path length of the sample. In Equation 1, the specific optical rotation α (λ) is a coefficient specific to the optical rotatory substance, and the optical path length L of the sample is also a known value before the concentration measurement, and therefore the optical rotation when the light beam is incident on the sample. By measuring θ (λ), the concentration c of the optical rotatory substance can be obtained.

As a measuring method of the conventional optical rotation, it is those for example as shown in FIG. In FIG. 5 , the light beam emitted from the light source 501 that emits parallel light passes through the polarizer 502 to become linearly polarized light having an optical axis in the transmission axis direction of the polarizer 502 and enters the sample 503. The light beam that has passed through the sample 503 enters the analyzer 504, and only the light component in the direction of the transmission axis of the analyzer 504 is transmitted and reaches the light receiving unit of the photodetector 505. Here, the analyzer 504 can be rotated by an analyzer rotator 506. At this time, the relative angle between the transmission axes of the polarizer 502 and the analyzer 504 is θ, and the intensity of the light detected by the photodetector 505 is I ₁ . If the sample has no optical rotation, the relationship between θ and I is expressed by Equation 2.
I ₁ = T × I ₀ × (cos ² θ) (Formula 2)
Here, T is the transmittance of the sample, and I ₀ is the intensity of light incident on the sample. It is assumed that there is no influence of reflection or the like on each optical element.

Next, assuming that the sample has optical rotation, assuming that the optical rotation by the sample is β, the light intensity I ₂ detected by the photodetector 505 is expressed by Equation 3.
I ₂ = T × I ₀ × (cos ² (θ−β)) (Formula 3)
Comparing Expression 2 and Expression 3, when the sample has optical rotation, the point where the intensity detected by the photodetector 505 becomes 0, that is, the extinction point is shifted by β. Therefore, the optical rotation by the sample can be measured by detecting the deviation of the extinction point.

However, in this method, since there is no modulation component, good S / N cannot be obtained, and it is difficult to accurately grasp the position of the extinction point. In order to improve the accuracy, a method of modulating the polarization direction of the light beam using a Faraday element is used. By modulating the polarization direction, a signal having only the modulation frequency component can be separated from other noise components, so that a signal with a high S / N can be taken out and the optical rotation can be measured with high accuracy. I can do it. For example, in Patent Document 1, a sample is irradiated with linearly polarized light modulated at a frequency f using a Faraday cell, and calculation is performed based on a detection signal when the modulation signal is maximum and minimum, thereby calculating the optical rotation. . In Patent Document 2, a magnetic field is applied to a test sample by a solenoid coil, and the optical rotation of the sample is measured based on the resulting change in polarization direction due to the Faraday effect.

JP-A-9-236542 (FIG. 1) JP-A-9-145605 (FIG. 1)

  However, the method described above has the following problems. In a conventional optical rotation measuring instrument, a Faraday cell is used for optical modulation. For example, when the modulation amount increases, the current supplied to the Faraday cell also increases, and it is necessary to increase the capacity of the driver. Further, since the amount of heat generated by the Faraday cell increases due to an increase in current, a cooling device or the like is required, and the entire device becomes large and complicated. Further, when performing frequency modulation, in order to improve the frequency characteristics, it is necessary to increase the modulation frequency. In this case, however, the vibration of the coil is increased, so that countermeasures against vibration and noise are required. For example, measures such as increasing the thickness of the insulating sheet sandwiched between the coil layers or pouring a resin for fixing the coil so as not to vibrate can be considered, but such measures promote the sealing structure of the coil. Since the temperature of the optical rotation measuring instrument itself rises due to the heat generated by the coil, a cooling device or the like is required as well. For this reason, the configuration of the polarimeter becomes complicated, and the scale of the apparatus must be increased.

  Accordingly, in order to eliminate the above-mentioned problems caused by the prior art, the present invention provides a rotation angle measurement device and a concentration measurement device that perform stable and high-precision measurement of the optical rotation of a sample, and are small in size and simple in structure. With the goal.

  In order to solve these problems, the optical rotation measuring device and the concentration measuring device according to the present invention employ the following means. That is, the optical rotation measuring device of the present invention includes linearly polarized light output means for outputting linearly polarized light, optical rotation modulation means for modulating the optical rotation of linearly polarized light, and linearly polarized light whose optical rotation is modulated by the optical rotation modulation means. And an analyzer that transmits only one direction component of transmitted light that is rotated by the optical rotatory substance in the sample and transmits through the sample, and light that detects the transmitted light transmitted through the analyzer. An optical rotation measuring device provided with a detection means, wherein the optical rotation modulation means is constituted by a liquid crystal element, and when the transmitted light in the analyzer is rotated based on signal information detected by the light detection means The optical rotation of the sample is measured from the angle of the analyzer.

  The optical rotation measuring device according to the present invention includes linearly polarized light output means for outputting linearly polarized light, optical rotation modulation means for modulating the optical rotation of the linearly polarized light, and linearly polarized light whose optical rotation is modulated by the optical rotation modulation means. By being emitted to the sample, an analyzer that transmits only one direction component of transmitted light that is rotated by the optical rotatory substance in the sample and passes through the sample, and transmitted light that passes through the analyzer are detected. An optical rotation measuring device provided with a light detection means for performing optical rotation for reference, which comprises a liquid crystal element, and does not pass through a sample by dividing linearly polarized light whose optical rotation is modulated by the liquid crystal element. The optical rotation is measured from the angle of the analyzer when the analyzer is rotated so that the signal information of the transmitted light in the reference optical system matches the signal information of the transmitted light passing through the sample. Characterized in that it.

Further, the optical rotation measuring device according to the present invention comprises a linearly polarized light output means for outputting linearly polarized light, an optical rotation modulation means for modulating the optical rotation of the linearly polarized light, and a linearly polarized light whose optical rotation is modulated by the optical rotation modulation means. And the analyzer that transmits only the unidirectional component of the transmitted light that is rotated by the optical rotatory substance in the sample and passes through the sample, and the transmitted light that passes through the analyzer is detected. An optical rotation measuring device provided with a light detection means, wherein the optical rotation modulation means is constituted by a liquid crystal element, and a reference optical system that does not pass through a sample by dividing linearly polarized light whose optical rotation is modulated by the liquid crystal element The angle of the analyzer when the analyzer is rotated so that the signal information of the transmitted light in the reference optical system and the signal information of the transmitted light passing through the sample are brought close to each other, and the reference optical And calculating the optical rotation with the differential component of the signal information and the signal information of the transmitted light sample coming through the transmitted light in.

  In the present invention, it is preferable that the linearly polarized light is modulated by the liquid crystal element so that the signal waveform of the transmitted light in the reference optical system has a maximum at a constant period and the maximum value is constant.

  In addition, the present invention provides a signal for transmitting light in the reference optical system as a driving voltage of the liquid crystal element so that the signal waveform of the transmitted light in the reference optical system has a maximum at a constant period and the maximum value is constant. It is preferable to feed back.

  In the present invention, when measuring the optical rotation of the sample, it is preferable to measure the sample and a reference sample having a known optical rotation, and correct the measured value of the sample with the measured value of the reference sample.

  In addition, the light source in the linearly polarized light output means in the present invention can be exchanged, and it is useful to measure the optical rotation of the sample at a plurality of wavelengths by using a plurality of light sources having different wavelengths.

  It is also useful to measure the optical rotation of the sample at the transmission wavelength in the filter by emitting the linearly polarized light output from the linearly polarized light output means in the present invention to a filter that transmits only light of one wavelength.

  The sample in the present invention is urine, and is useful when the optical rotatory substance in the sample is urine sugar, urine amino acid, or urine protein.

  Further, the concentration measuring apparatus of the present invention is characterized in that the concentration of a substance in a sample is calculated from the optical rotation measured by the optical rotation measuring apparatus.

(Function)
Polarization direction of linearly polarized light using a liquid crystal element as an optical rotation modulation element in an optical rotation measurement apparatus that measures the optical rotation of a sample and a concentration measurement apparatus that measures the optical rotation of a sample by measuring the optical rotation Using the angle of the analyzer when the analyzer is rotated based on the signal information of the transmitted light that the linearly polarized light whose optical rotation is modulated by the liquid crystal element is transmitted through the sample and the analyzer. Alternatively, a reference optical system that does not pass through the sample is provided by dividing linearly polarized light so that the signal information of the transmitted light in the reference optical system matches the signal information of the transmitted light that passes through the sample. Optical rotation using the difference component between the angle of the analyzer when the analyzer is rotated, or the angle of the analyzer, and the signal information of the transmitted light in the reference optical system and the signal information of the transmitted light passing through the sample Calculate degree The Rukoto, optical rotation measurement of the sample performed stably and highly accurately, and it is possible to a simple structure in small size.

  As described above, the optical rotation measuring device and the concentration measuring device of the present invention have the effects described below.

  A liquid crystal element that can be driven with a small size and a low voltage without using a Faraday element in an optical rotation measuring device that measures the optical rotation of a sample and a concentration measuring device that measures the optical rotation of a sample by measuring the optical rotation. By modulating the polarization direction of the light beam, it is possible to reduce the size of the entire device, simplify the structure, and reduce the power consumption. Can be measured. In addition, modulation is performed using a liquid crystal element, and the optical rotation is measured using the angle of the analyzer when the analyzer is rotated based on the signal information of the transmitted light transmitted through the sample and the analyzer. Therefore, even when the optical rotation angle is large, measurement can be easily performed.

  In addition, a reference optical system that does not pass through the sample is provided by dividing linearly polarized light so that the signal information of the transmitted light in the reference optical system matches the signal information of the transmitted light that passes through the sample. By using the optical rotation using the angle of the analyzer when the photon is rotated, stable measurement can be performed even when the modulation signal changes.

  In addition to the angle of the analyzer when the analyzer is rotated so that the signal information of the transmitted light in the reference optical system matches the signal information of the transmitted light passing through the sample, the reference information at that time By calculating the optical rotation using the difference component between the signal information of the transmitted light and the signal information of the transmitted light passing through the sample in this optical system, it becomes possible to measure the optical rotation with higher accuracy.

  In addition, by feeding back to the driving voltage of the liquid crystal element using the signal in the reference optical system, stable polarization direction modulation can always be performed even when the surrounding environment such as temperature changes. Optical rotation measurement can be performed stably and with high accuracy.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an optical rotation measuring device and a concentration measuring device using the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an example of the first embodiment of the present invention. In FIG. 1, a light beam emitted from a light source 101 such as a laser diode driven by a drive circuit 113 enters a collimator lens 102. Here, the light source 101 emits a light beam having a certain wavelength, and is not limited to a laser diode. The collimator lens 102 converts incident light into parallel light, and changes the position according to the spread angle of the light from the light source. Next, the light beam converted into parallel light by the collimator lens 102 passes through the slit 103 and enters the polarizer 104. Since the slit 103 is used only for the purpose of narrowing the irradiation range of the light beam, it may be omitted depending on circumstances. The light beam becomes linearly polarized light having an optical axis in the transmission axis direction of the polarizer 104 by the polarizer 104. In this embodiment, the transmission axis of the polarizer 104 is the y-axis direction. Next, linearly polarized light transmitted through the polarizer 104 is incident on the liquid crystal element 105. In the present embodiment, the liquid crystal element 105 is homogeneously oriented in the direction of 45 degrees with respect to the y-axis, and the light rays that have passed through the liquid crystal element 105 become elliptically polarized light having axes in the x and y directions, and the ellipticity is the liquid crystal The voltage varies depending on the voltage applied to the liquid crystal by the drive circuit 114. Next, the light beam enters the λ / 4 wavelength plate 106. Here, the λ / 4 wavelength plate 106 has an axis in the y-axis direction, and the light beam that has passed through the λ / 4 wavelength plate 106 becomes linearly polarized light. At this time, the polarization direction of the linearly polarized light depends on the ellipticity of the light beam that has passed through the liquid crystal element 105, and thus varies depending on the voltage applied to the liquid crystal element 105. Therefore, the liquid crystal element 105 can modulate the polarization direction of linearly polarized light.

Then, the light rays modulated by the liquid crystal element 105 is incident on the sample cell 108 containing the specimen. Here, when the light beam passing through the sample cell 108 passes through the sample, it is rotated by an unknown displacement amount by the optical rotatory substance in the sample. The amount of displacement at this time is proportional to the concentration of the optical rotatory substance in the sample and the length of the optical path length of the light beam passing through the sample. Here, the surface through which the light beam passes in the sample cell 108 needs to be transparent with high transmittance so as not to absorb much light, and examples thereof include glass.

  The light beam that has passed through the sample cell 108 then enters the analyzer 109. In the analyzer 109, only the light component in the transmission axis direction of the analyzer 109 is transmitted and reaches the light receiving unit of the photodetector 110. Here, the analyzer 109 is connected to a gear 115 and can be rotated by a motor 116, and the transmission axis direction is variable. The light detector 110 outputs the received light intensity as a voltage signal, and the output signal is amplified by an amplifier or the like and input to a computing unit 117 such as a PC. The computing unit 117 not only performs computation but also controls the liquid crystal drive circuit 114 and the motor 116 as a controller, and the result calculated by the computing unit 117 is transferred to the display means 118 and displayed.

  At this time, the optical rotation of the sample is measured using the signal information input to the calculator 117 and the angle data of the analyzer 109 whose angle has been changed by the motor 116. An example of the measurement method is described below. For example, the voltage for driving the liquid crystal element 105 is an arbitrary frequency f, and the polarization direction of linearly polarized light having the optical axis in the y-axis direction passes through the liquid crystal element 105 and the λ / 4 wavelength plate 106 and then the y-axis. Modulation is performed at a modulation angle ± δ and a frequency f. At this time, assuming that the transmission axis direction of the analyzer 109 is the x-axis, the signal obtained by the photodetector 110 has a constant maximum value as shown in FIG. 2A when there is no optical rotatory substance in the sample. Thus, the waveform has a frequency of 2f. In FIG. 2, the horizontal axis indicates the time axis, and the vertical axis indicates the intensity of the detected light beam. Here, when an optical rotatory substance is present in the sample, if the amount of light rotated by the optical rotatory substance in the sample is γ, the light beam reaching the analyzer 109 is from (−δ + γ) to (−δ + γ) ( The polarization direction is displaced in the angular range of (δ + γ). At this time, the maximum value as shown in FIG. 2A is constant from the signal obtained by the photodetector 110, and the waveform having the frequency 2f cannot be obtained. Therefore, while observing the signal obtained from the photodetector 109, the motor 116 is controlled to rotate the analyzer 109 to an angle at which a waveform as shown in FIG. As a signal processing method, for example, the maximum value appearing at the frequency 2f is measured, and the analyzer 109 is rotated so that the difference between the maximum values becomes 0, or the analyzer 109 so that the ratio of the maximum values becomes 1. And a method of rotating the. Since the rotation angle of the analyzer 109 at this time becomes the optical rotation by the sample 108, the optical rotation can be measured.

  By using a liquid crystal element that can be driven by a small size and a low voltage by this method, there is no need for a vibration countermeasure or a cooling device for heat countermeasures in particular, so the entire apparatus can be downsized and the structure simplified. Measurement with low power consumption is possible.

  In addition, when the optical rotatory substance in the sample is known and the specific optical rotation is known before the measurement, the concentration of the optical rotatory substance can be determined by calculating the optical rotation according to Equation 1. Therefore, a small and highly accurate concentration measuring apparatus can be provided in the same manner.

  In actual measurement, the measurement value may fluctuate due to the influence of the sample cell. Therefore, when measuring the optical rotation of the sample, a sample and a reference sample with known optical rotation, such as pure water, are used. More accurate measurement is possible by measuring and correcting the measured value of the sample with the measured value of the reference sample.

  In this embodiment, a light source that emits light of a certain wavelength, such as a laser diode, is used as the light source. However, the present invention is not limited to this, and light of a specific wavelength is emitted by using a filter or the like. A method is also conceivable.

(Second embodiment)
FIG. 3 shows an example of the second embodiment of the present invention. In FIG. 3, the optical elements and the like are the same as those in the first embodiment. Similar to the first embodiment, the light beam emitted from the light source 101 such as a laser diode driven by the drive circuit 113 is incident on the collimator lens 102. The collimating lens 102 converts incident light into parallel light, and changes its position according to the spread angle of the light from the light source. Next, the light beam that has been collimated by the collimator lens 102 passes through the slit 103 and enters the polarizer 104. The light beam becomes linearly polarized light having an optical axis in the transmission axis direction of the polarizer 104 by the polarizer 104. In this embodiment, the transmission axis of the polarizer 104 is the y-axis direction. Next, the linearly polarized light transmitted through the polarizer 104 enters the liquid crystal element 105 and the λ / 4 wavelength plate 106. Here, the polarization direction of linearly polarized light is modulated as in the first embodiment.

  Next, the light beam modulated by the liquid crystal element 105 enters the light branching means 207 such as a beam splitter. The light beam splitting means 207 splits the two light beams into a transmission direction and a reflection direction, respectively. Here, a light beam in the transmission direction is a light beam A, and a light beam in the reflection direction is a light beam B. The light beam A then enters the sample cell 108 containing the sample. Here, when the light beam A passing through the sample cell 108 passes through the sample, it is rotated by an unknown displacement amount by the optical rotatory substance in the sample.

  The light beam A that has passed through the sample cell 108 then enters the first analyzer 309. In the first analyzer 309, only the light component in the transmission axis direction of the first analyzer 309 is transmitted and reaches the light receiving unit of the first photodetector 310. Here, the first analyzer 309 is connected to the gear 115 and can be rotated by the motor 116, and the transmission axis direction is variable. The first photodetector 310 outputs the received light intensity as a voltage signal, and the output signal is amplified by an amplifier or the like and input to a computing unit 117 such as a PC. As in the first embodiment, the computing unit 117 not only performs computation but also controls the liquid crystal drive circuit 114 and the motor 116 as a controller, and the result calculated by the computing unit 117 is transferred to the display means 118 and displayed. .

  Of the light beams branched by the light branching means 107, the light beam B in the reflection direction then enters the second analyzer 311. In the second analyzer 311, only the light component in the direction of the transmission axis of the second analyzer 311 is transmitted and reaches the light receiving unit of the second photodetector 312. Similar to the first photodetector 310, the second photodetector 312 outputs the received light intensity as a voltage signal change, and the output signal is amplified by an amplifier or the like and input to the computing unit 117. To do.

  At this time, the optical rotation of the sample is measured using the signal information input to the calculator 117 and the angle data of the first analyzer 309 whose angle has been changed by the motor 116. An example of the measurement method is described below. For example, the voltage for driving the liquid crystal element 105 is an arbitrary frequency f, and the polarization direction of linearly polarized light having the optical axis in the y-axis direction passes through the liquid crystal element 105 and the λ / 4 wavelength plate 106 and then the y-axis. Modulation is performed at a modulation angle ± δ and a frequency f. At this time, assuming that the transmission axis direction of the second analyzer 311 is the x-axis direction, a waveform as shown in FIG. That is, since the extinction point passes twice while the angle is modulated for one period, a waveform having a constant maximum value at the frequency 2f is observed. Here, it is assumed that the polarizer 104, the first analyzer 309, and the second analyzer 311 do not completely transmit light in a crossed Nicol state.

  Here, many liquid crystal molecules have temperature characteristics, and it is considered that the amount of modulation by the liquid crystal element 105 changes due to a change in ambient temperature or the like. In that case, the signal waveform obtained by the second photodetector 312 is not the waveform of the frequency 2f as shown in FIG. 2 (a), for example, the wave height ratio is shifted as shown in FIG. 2 (b). Waveforms may be observed. Therefore, the signal waveform obtained by the second photodetector 312 is fed back to the liquid crystal driving circuit 114, and the liquid crystal element 105 is driven while adjusting so that the waveform always becomes as shown in FIG. To do.

  Next, the light A is rotated by an unknown amount by the optical rotatory substance in the sample. If the unknown amount is γ, the polarization direction of the light ray A reaching the first analyzer 309 is modulated in the angular range from (−δ + γ) to (δ + γ) with respect to the y-axis. At this time, assuming that the transmission axis direction of the first analyzer 309 is the x-axis, a waveform having a frequency 2f as shown in FIG. 2A is obtained from the signal obtained by the first photodetector 310. Absent. Therefore, while observing the signal obtained from the first photodetector 309, the motor 116 is controlled to rotate the first analyzer 309 to an angle at which the waveform as shown in FIG. As a signal processing method, for example, the maximum value appearing at the frequency 2f is measured, and the first analyzer 309 is rotated so that the difference between the maximum values becomes 0, or the ratio of the maximum values becomes 1. For example, a method of rotating the first analyzer 309 may be used. Since the rotation angle of the first analyzer 309 at this time becomes the optical rotation by the sample 108, the optical rotation can be measured.

  By this method, as in the first embodiment, by using a liquid crystal element that can be driven with a small size and a low voltage, there is no need for a vibration countermeasure, a cooling device for heat countermeasures, etc. Can be simplified, and measurement with lower power consumption is possible.

  In addition, even if the ambient temperature changes due to the temperature characteristics of the liquid crystal element, a reference optical path is provided and feedback is provided using a signal obtained from the reference optical path. The optical rotation can be measured with high accuracy.

  Further, as in the first embodiment, when the optical rotatory substance in the sample is known and the specific optical rotation is known before the measurement, the optical rotatory substance is obtained by calculating the optical rotation according to Equation 1. Therefore, it is possible to provide a small and highly accurate concentration measuring apparatus.

  Further, as in the first embodiment, in actual measurement, there is a possibility that the measured value may fluctuate due to the influence of the sample cell or the like. Therefore, when measuring the optical rotation of the sample, the sample and, for example, pure water, etc. More accurate measurement is possible by measuring a reference sample with a known optical rotation and correcting the measured value of the sample with the measured value of the reference sample.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. The optical elements and the like are the same as those in the first embodiment. Similar to the first embodiment, the light beam emitted from the light source 101 such as a laser diode driven by the drive circuit 113 is incident on the collimator lens 102. Next, the light beam that has been collimated by the collimator lens 102 passes through the slit 103 and enters the polarizer 104 having the transmission axis in the y-axis direction. The light beam becomes linearly polarized light having an optical axis in the y-axis direction of the polarizer 104 by the polarizer 104, and then the linearly polarized light transmitted through the polarizer 104 enters the liquid crystal element 105 and the λ / 4 wavelength plate 106. Here, the polarization direction of linearly polarized light is modulated as in the first embodiment.

Next, the light beam modulated by the liquid crystal element 105 is incident on the light branching means 107 such as a beam splitter, and is divided into a light beam A in the transmission direction and a light beam B in the reflection direction. The light beam A then enters the sample cell 108 and, when passing through the sample, is rotated by an unknown displacement amount by the optical rotatory material in the sample. Next, the light beam A enters the first analyzer 309, and only the light component in the transmission axis direction of the first analyzer 309 is transmitted and reaches the light receiving unit of the first photodetector 310. Here, like the second embodiment, the first analyzer 309 is connected to the gear 115 and can be rotated by the motor 401, and the transmission axis direction is variable. The first photodetector 310 outputs the received light intensity as a voltage signal, and the output signal is amplified by an amplifier or the like and input to a computing unit 117 such as a PC. The computing unit 117 not only performs computation but also controls the liquid crystal driving circuit 114 and the motor 401 as a controller, and the result calculated by the computing unit 117 is transferred to the display means 118 and displayed.

  Of the light beams branched by the light branching means 107, the light beam B in the reflection direction then enters the second analyzer 311 and transmits only the light component in the transmission axis direction of the second analyzer 311. It reaches the light receiving part of the second photodetector 312. Similar to the first photodetector 310, the second photodetector 312 outputs the received light intensity as a voltage signal change, and the output signal is amplified by an amplifier or the like and input to the computing unit 117. To do.

At this time, the optical rotation of the sample is measured using the signal information input to the calculator 117 and the angle data of the first analyzer 309 whose angle has been changed by the motor 401. An example of the measurement method is described below. For example, the voltage for driving the liquid crystal element 105 is an arbitrary frequency f, and the polarization direction of linearly polarized light having the optical axis in the y-axis direction passes through the liquid crystal element 105 and the λ / 4 wavelength plate 106 and then the y-axis. modulation angle ± [delta], if you like modulated at a frequency f, as in the second embodiment, the second signal waveform obtained from the photodetector 312 FIGS. 2 (a) to show such frequency 2f waveform It becomes. At this time, as in the second embodiment, the signal waveform obtained by the second photodetector 312 is fed back to the liquid crystal drive circuit 114, and the liquid crystal element 105 is adjusted while adjusting so that the waveform always has the frequency 2f. To drive.

  Next, the light A is rotated by an unknown amount by the optical rotatory substance in the sample. Therefore, assuming that the transmission axis direction of the first analyzer 309 is the x-axis, the signal obtained by the first photodetector 310 cannot obtain the waveform of the frequency 2f as shown in FIG. . Therefore, the motor 401 is controlled while observing the signal obtained from the first photodetector 309, and the first analyzer 309 is rotated to an angle at which a waveform as shown in FIG.

Here, the motor 401 in this embodiment is simple and it is difficult to control the angle with very high accuracy. However, the structure is simpler and smaller than a high-precision motor. In the present embodiment, assuming that the rotation angle of the first analyzer can be controlled in increments of 0.1 degrees by the motor 401, the angle data of the first analyzer 309 as in the second embodiment. The resolution of the optical rotation measured using only is 0.1 degrees.

  Therefore, in addition to the angle data of the first analyzer 309, the optical rotation calculated from the difference component between the signal information in the first photodetector 310 and the signal information in the second photodetector 312 is used. By calculating the optical rotation, it is possible to perform highly accurate measurement even when a control system with inferior accuracy is used. For example, even when the first analyzer 309 is rotated by the motor 401 so that the signal in the second photodetector 312 and the signal in the first photodetector 310 are as close as possible, the control by the motor 401 is performed. It is conceivable that the signal in the first photodetector 310 is not exactly a signal having the frequency 2f due to the limit of the resolution. Therefore, in addition to the angle of the first analyzer 309 at that time, the maximum value appearing at the frequency 2f of the signal waveform obtained by the first photodetector 310 is measured, and the difference between the maximum values and the ratio of the maximum values are determined. And a method for calculating the optical rotation using the method. For example, when using the ratio of the maximum values, a relational expression between the ratio of the maximum values and the optical rotation is constructed in advance, and the optical rotation is calculated corresponding to the ratio of the maximum values according to the relational expression. That is, since the optical rotation of the deviation between the actual optical rotation and the first analyzer 309 can be calculated, the motor rotation can be obtained by adding the calculated optical rotation to the angle of the first photodetector 309. It is possible to measure up to a high-precision area that could not be measured due to the limit of resolution of control by 401.

  In the present embodiment, in addition to the measurement by the mechanical operation by the motor, the measurement is further performed by using the signal waveform. For example, a control system for the rotation of the analyzer such as a very high-precision motor is required. Even if a simple control system is used, highly accurate measurement is possible. Thereby, the whole apparatus can be made into a simple structure, and size reduction is attained.

  Further, as in the first embodiment, when the optical rotatory substance in the sample is known and the specific optical rotation is known before the measurement, the optical rotatory substance is obtained by calculating the optical rotation according to Equation 1. Therefore, it is possible to provide a small and highly accurate concentration measuring apparatus.

  Further, as in the first embodiment, in actual measurement, there is a possibility that the measured value may fluctuate due to the influence of the sample cell or the like. Therefore, when measuring the optical rotation of the sample, the sample and, for example, pure water More accurate measurement is possible by measuring a reference sample with a known optical rotation and correcting the measured value of the sample with the measured value of the reference sample.

It is a figure which shows the structure of the optical rotation measuring apparatus in 1st embodiment of this invention. It is a figure which shows the output waveform of the photodetector in embodiment of this invention. It is a figure which shows the structure of the optical rotation measuring apparatus in 2nd embodiment of this invention. It is a figure which shows the structure of the optical rotation measuring apparatus in 3rd embodiment of this invention. It is the schematic of the optical rotation measuring apparatus in a prior art example.

Explanation of symbols

101 light source 102 collimating lens 104 first polarizer 105 liquid crystal element 106 λ / 4 wavelength plate 107 light branching means 109 analyzer 114 liquid crystal driving circuit 116 motor 309 first analyzer 310 first photodetector 311 second Analyzer 312 Second photodetector 401 Motor

Claims (9)

Linearly polarized light output means for outputting linearly polarized light;
Optical rotation modulation means for modulating the optical rotation of the linearly polarized light,
The linearly polarized light whose optical rotation is modulated by the optical rotation modulation means is emitted to the sample, so that only one-directional component of transmitted light that is rotated by the optical rotatory substance in the sample and passes through the sample is transmitted. Analyzer to
An optical rotation measuring device provided with a light detecting means for detecting transmitted light transmitted through the analyzer,
The optical rotation modulation means is constituted by a liquid crystal element,
Providing a reference optical system that does not pass through the sample by dividing linearly polarized light whose optical rotation is modulated by the liquid crystal element;
The optical rotation is measured from the angle of the analyzer when the analyzer is rotated so that the signal information of the transmitted light in the reference optical system matches the signal information of the transmitted light passing through the sample. Optical rotation measuring device. Linearly polarized light output means for outputting linearly polarized light;
Optical rotation modulation means for modulating the optical rotation of the linearly polarized light,
The linearly polarized light whose optical rotation is modulated by the optical rotation modulation means is emitted to the sample, so that only one direction component of the transmitted light that is rotated by the optical rotatory substance in the sample and passes through the sample is transmitted. Analyzer to
An optical rotation measuring device provided with a light detecting means for detecting transmitted light transmitted through the analyzer,
The optical rotation modulation means is constituted by a liquid crystal element,
Providing a reference optical system that does not pass through the sample by dividing linearly polarized light whose optical rotation is modulated by the liquid crystal element;
The angle of the analyzer when the analyzer is rotated so that the signal information of the transmitted light in the reference optical system and the signal information of the transmitted light passing through the sample are brought close to each other, and the reference information An optical rotation measuring device that calculates an optical rotation using a difference component between signal information of transmitted light in an optical system and signal information of transmitted light passing through the sample. By the liquid crystal element, a signal waveform of the transmitted light in the optical system for the reference, takes the maximum at a certain period, according to claim 1 or claim maximum value is equal to or modulating the linearly polarized light to be constant Optical rotation measurement device according to 2. The transmitted light signal in the reference optical system is fed back to the driving voltage of the liquid crystal element so that the signal waveform of the transmitted light in the reference optical system takes a maximum at a constant period and the maximum value becomes constant. Optical rotation measurement device according to claim 3, characterized in that to. The measurement value of the sample is corrected with the measured value of the reference sample by measuring the sample and a reference sample with a known optical rotation when measuring the optical rotation of the sample. The optical rotation measuring device according to any one of claims 1 to 4 . A light source is replaceable in said linearly polarized output unit, by using a plurality of light sources of different wavelengths, from claim 1, characterized in that the measurement of optical rotation of the sample at a plurality of wavelengths of claim 5 The optical rotation measuring apparatus as described in any one of Claims. The linearly polarized light output from the linearly polarized light output means is emitted and transmitted through a filter that transmits only light of one wavelength, and the optical rotation of the sample is measured at a transmission wavelength in the filter. The optical rotation measuring apparatus as described in any one of Claims 6 . The optical rotation measurement according to any one of claims 1 to 7 , wherein the sample is urine, and the optical rotatory substance in the sample is urine sugar, urine amino acid or urine protein. apparatus. From optical rotation measured in optical rotation measurement device as claimed in any one of claims 8, concentration measuring device for calculating the concentration of the optical active substance in the sample.

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