Polarimeter, calibration method therefor, and polarimeter calibration program

Abstract

To provide a polarimeter that does not require replacement of components when performing calibration, and can perform calibration quickly, simply and precisely over a wide wavelength range by using a standard rotation angle of a polarizer instead of a standard sample.SOLUTION: A polarimeter can be calibrated using a rotation angle of a polarizer measured by rotating the polarizer. The polarimeter has: a light source; a polarizer; polarizer rotation means; an angle encoder that is attached to the polarizer, and measures an angle by which the polarizer is rotated; an analyzer; analyzer rotation means; detection means; and control means for performing processing of, during calibration of the polarimeter, rotating the polarizer using the polarizer rotation means when there is no sample or cell in a sample chamber, and comparing a standard rotation angle that the rotation angle of the polarizer is measured by the angle encoder, with an angle of rotation, which is an angle by which the analyzer rotation means rotates the analyzer from a rotation position where the amount of light received by the detection means is minimized to a rotation position where the amount of light received is minimized when linearly polarized light is rotated and the amount of light received is no longer minimum.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a polarimeter, a polarimeter calibration method, and a polarimeter calibration program that can perform calibration using a standard rotation angle of a polarizer measured by rotating the polarizer instead of a standard sample. [Background technology]

[0002] Polarimeters are periodically calibrated to maintain the accuracy of measurement data such as the angle of rotation. Calibration is typically performed in the wavelength range of 546 nm to 900 nm using a sucrose solution or a quartz optical rotatory plate as a standard sample. Specifically, the angle of rotation at a wavelength of, for example, 589 nm is measured using a sucrose solution or a quartz optical rotatory plate as a standard sample, and the obtained angle of rotation is compared with a reference value set forth in a publicly available standard (e.g., Japanese Industrial Standards (JIS) or the International Commission for Uniform Methods of Sugar Analysis (ICUMSA)). If the measured angle of rotation of the sucrose solution or quartz optical rotatory plate falls within the allowable range of the reference value, the calibration is deemed successful. For example, Non-Patent Document 1 describes the reference value for the specific optical rotation of a 5% to 50% by mass sucrose solution. Furthermore, Non-Patent Document 2 describes the reference values ​​for the angle of rotation of a 26% by mass sucrose solution and a quartz optical rotatory plate.

[0003] The calibration using sucrose aqueous solutions requires time and effort to prepare multiple sucrose aqueous solutions with different optical rotations, and there is also the problem that a certain degree of error occurs in the optical rotation when preparing the sucrose aqueous solutions. On the other hand, although the calibration using the quartz optical rotatory plate can avoid the problems caused by the preparation of the sucrose aqueous solution, there are problems in that the quartz optical rotatory plate is expensive and it is difficult to adjust the thickness. As described above, conventional polarimeters are calibrated using a sucrose solution or a quartz optical rotation plate as a standard sample, and therefore cannot be said to be able to perform a fully satisfactory calibration, and there is a problem in that the accuracy of the optical rotation cannot be improved beyond a certain level.

[0004] In order to solve the above problems, a polarimeter has been proposed in which, during calibration, the sample cell is replaced with a half-wave plate and its rotation means, and calibration can be performed using the rotation angle of the half-wave plate measured by rotating the half-wave plate (see, for example, Patent Document 1). Fig. 1 is a schematic perspective view showing the polarimeter described in Patent Document 1. The polarimeter in Fig. 1 includes a light source 31, an interference filter 32, a lens 33, a polarizer 11, a Faraday cell 12, a sample cell 13, an analyzer 14, a hollow motor 15, a lens 34, and a light-receiving element 16.

[0005] When measuring a sample, a sample having optical rotation is placed in the sample cell 13 in Fig. 1, and the plane of polarization of linearly polarized light is rotated by the sample, and linearly polarized light parallel to the transmission axis of the analyzer 14 is transmitted through the analyzer 14, and the linearly polarized light is detected by the light receiving element 16. The analyzer 14 is rotated while detecting the amount of light transmitted through the analyzer 14, and the rotation angle of the analyzer 14 at which the amount of light transmitted through the analyzer 14 is minimized is found, thereby determining the angle by which the plane of polarization of the linearly polarized light is rotated when it passes through the sample, i.e., the optical rotation of the sample.

[0006] On the other hand, during calibration, as shown in FIG. 2, a half-wave plate 17 and a rotating means for the half-wave plate (high-precision hollow motor 18) are provided instead of the sample cell 13, and the half-wave plate 17 is rotated by the rotation of the high-precision hollow motor 18, thereby rotating the polarization plane of the incident linearly polarized light. This rotation angle is defined as the rotation angle of the half-wave plate 17. Linearly polarized light whose polarization plane has been rotated by the half-wave plate 17 is incident on the analyzer 14, and the analyzer 14 is rotated while detecting the amount of light transmitted through the analyzer 14. The rotation angle of the analyzer 14 at which the amount of light transmitted through the analyzer 14 is minimized is measured to determine the angle of rotation, and calibration is performed by comparing this angle of rotation with the rotation angle of the half-wave plate 17.

[0007] Furthermore, in recent years, technological advances in light sources and other aspects of polarimeters have made it possible to measure reliable data even at wavelengths shorter than 546 nm (for example, 250 nm to 545 nm). Accordingly, particularly in the pharmaceutical industry, there is a demand for polarimeters to be able to be calibrated at wavelengths shorter than 546 nm, since measurement data within the calibrated wavelength range can be used as evidential data for quality control. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-117163 [Non-patent literature]

[0009] [Non-Patent Document 1] JIS K0063-1992 "Method for measuring optical rotation of chemical products" (1992) [Non-patent document 2] ICUMSA Specification and Standard SPS-1(2017)-Polarimetry and the International Sugar Scale-Official, published by International Commission for Uniform Methods of Sugar Analysis (2017) Summary of the Invention [Problem to be solved by the invention]

[0010] However, as mentioned above, calibration using the sucrose aqueous solution has problems related to the preparation of the sucrose aqueous solution. Meanwhile, in order to obtain an optical rotation with a precision suitable for calibration at wavelengths shorter than 546 nm, the quartz rotatory optical plate must be thinned, but it has been difficult to stably and inexpensively process such a thin quartz rotatory optical plate. Furthermore, neither the sucrose aqueous solution nor the quartz rotatory optical plate has reference values ​​for wavelengths shorter than 546 nm as set forth in standards such as JIS or ICUMSA, and they are therefore not suitable as standard samples for use at wavelengths shorter than 546 nm.

[0011] When performing calibration with the polarimeter of Patent Document 1, the sample cell 13 must be removed and the high-precision hollow motor 18 and half-wave plate 17 must be installed, and after calibration is complete, the high-precision hollow motor 18 and half-wave plate 17 must be removed and the sample cell 13 must be replaced and operation must be confirmed before sample measurement can be performed. Therefore, the calibration process is time-consuming and labor-intensive, and expensive replacement parts such as the high-precision hollow motor 18 and half-wave plate 17 must be prepared before calibration, resulting in a problem of a large number of parts and complicated management. Furthermore, the half-wave plate used in Patent Document 1 is wavelength-dependent, and even a slight change in wavelength prevents the target phase difference from being obtained, resulting in elliptically polarized light, which poses a problem that the correct polarization state cannot be obtained unless a half-wave plate suitable for the wavelength to be calibrated is used. Therefore, to perform calibration over a wide wavelength range, including wavelengths shorter than 546 nm, it is necessary to prepare a large number of half-wave plates and select a half-wave plate for each wavelength to perform calibration, which poses the problem of requiring time, effort, and cost.

[0012] The present invention aims to solve the above-mentioned problems of the prior art and to achieve the following object: That is, the present invention aims to provide a polarimeter, a method for calibrating a polarimeter, and a program for calibrating a polarimeter that do not require replacement of parts when performing calibration and that can perform calibration quickly, simply, and accurately over a wide wavelength range, including wavelengths shorter than 546 nm, by using a standard rotation angle of a polarizer measured by rotating the polarizer instead of a standard sample. [Means for solving the problem]

[0013] The polarimeter disclosed in the present invention is a polarimeter that can be calibrated using the rotation angle of a polarizer measured by rotating the polarizer. The polarimeter includes a light source, a polarizer that converts incident light from the light source into linearly polarized light parallel to a single transmission axis, a polarizer rotation means that rotates the polarizer around the transmission axis when calibrating the polarimeter, an angle encoder attached to the polarizer and measuring the angle by which the polarizer has rotated, an analyzer that receives the linearly polarized light generated by the polarizer and transmits linearly polarized light parallel to a specific transmission axis, an analyzer rotation means that rotates the analyzer to change the direction of the transmission axis, and a means for receiving and detecting the linearly polarized light that has passed through the analyzer. and control means for performing processing to compare, during calibration of the polarimeter, the standard rotation angle measured by an angle encoder when there is no sample or cell in the sample setting section of the sample chamber by rotating the polarizer by the polarizer rotation means and the angle by which the polarizer has rotated with the angle of rotation of the analyzer by the analyzer rotation means from the rotation position of the analyzer at which the amount of light received by the detection means is minimum to the rotation position of the analyzer at which the amount of light received is minimum when the linearly polarized light has rotated and the amount of light received is no longer minimum.

[0014] The polarimeter of the present invention can perform simple and precise calibration over a wide wavelength range, including wavelengths shorter than 546 nm (e.g., 250 nm to 545 nm), by using the standard rotation angle of the polarizer measured by rotating the polarizer instead of a standard sample. Furthermore, when performing calibration, the polarimeter of the present invention does not require the replacement of parts, such as removing the sample cell from the device and installing a high-precision hollow motor and a half-wave plate, as is the case with the polarimeter described in Patent Document 1 (JP 2010-117163 A), and calibration can be performed quickly and easily using the same device configuration as when measuring a sample.

[0015] In one aspect of the present invention, the control means calculates the difference between the standard rotation angle and the optical rotation as correction data, and if the correction data exceeds a threshold, corrects the optical rotation using the correction data. According to this aspect, by calculating the difference between the standard rotation angle and the optical rotation as correction data and correcting the optical rotation using the correction data if the correction data exceeds a threshold, more accurate measurement can be achieved.

[0016] In one aspect of the present invention, the standard rotation angle is the rotation angle of a polarizer measured using an angle encoder calibrated with an angle measuring device certified as a specific standard. The standard rotation angle satisfies the angle standard based on the Metrology Act and can be used to calibrate a polarimeter in place of a standard sample.

[0017] In one aspect of the present invention, the angle encoder is a rotary encoder with guaranteed traceability. According to this aspect, the rotation angle of the polarizer can be accurately measured as the optical rotation by attaching an angle encoder to the polarizer. By using a rotary encoder with guaranteed traceability as the angle encoder, the traceability of the rotation angle of the polarizer is also guaranteed.

[0018] In one embodiment of the present invention, the polarimeter is used for calibration in the wavelength range of 250 nm to 900 nm. According to this embodiment, calibration in the polarimeter of the present invention is performed using the rotation angle of the polarizer measured by rotating the polarizer, so that calibration is not wavelength dependent and can be performed simply and accurately over a wide wavelength range including wavelengths shorter than 546 nm. The polarimeter of the present invention can be used over a wide wavelength range, and even if a change in the plane of polarization occurs at any wavelength, the change can be cleared the moment calibration is performed based on the zero position, so there is no wavelength dependency.

[0019] In one aspect of the present invention, the optical fiber includes a second light source disposed near the light source, and linearly polarized light obtained by converting incident light from the second light source using a polarizer passes through a modulation means, a sample chamber other than the sample placement section, and a second analyzer, and a control means generates a signal as a DC component by using a control means to cancel out the fluctuation in the polarization plane of the linearly polarized light from a detection signal including an AC component and a fluctuation in the polarization plane of the linearly polarized light detected by a second detection means, combines the generated DC component with the AC component by a driver to obtain an AC component + DC component, and drives the modulation means using the AC component + DC component. According to this aspect, the inclusion of a polarization plane fluctuation correction means that corrects the fluctuation in the polarization plane of the linearly polarized light makes it possible to correct fluctuations in the balance position (the position where the amount of light received by the detection means is minimum), thereby enabling more accurate measurement of the optical rotation.

[0020] In one aspect of the present invention, the optical rotation measuring device includes a second polarizer that replaces the polarizer and splits incident light from a light source into first and second linearly polarized light, a measuring device that measures the optical rotation of the sample by passing the first linearly polarized light through a modulation device, a sample mounting section, an analyzer, and a detection device, and a polarization plane variation correction device that corrects the variation in the polarization plane of the linearly polarized light by generating a DC component using a control device from a detection signal that includes an AC component and a variation in the polarization plane of the linearly polarized light detected by the second detection device when the second linearly polarized light passes through the modulation device, a sample chamber other than the sample mounting section, and the second analyzer, combining the generated DC component with the AC component using a driver to obtain an AC component + DC component, and driving the modulation device with the AC component + DC component. According to this aspect, the polarization plane variation correction device that corrects the variation in the polarization plane of the linearly polarized light can correct the variation in the balance position (the position where the amount of light received by the detection device is minimum) and enables the optical rotation to be measured more accurately.

[0021] In one embodiment of the present invention, the second polarizer is a Rochon prism. By using a Rochon prism as the second polarizer, incident light from a light source can be split into first linearly polarized light and second linearly polarized light having different optical axes.

[0022] The polarimeter calibration method disclosed in the present invention performs calibration using the rotation angle of the polarizer measured by rotating the polarizer. The polarimeter calibration method includes a standard rotation angle acquisition step of rotating the polarizer without a sample or cell in the sample mounting section of the sample chamber and measuring the angle of rotation of the polarizer with an angle encoder to acquire a standard rotation angle, an optical rotation acquisition step of measuring the angle of rotation of the analyzer from the analyzer rotation position at which the amount of light received by the detection means is minimized to the analyzer rotation position at which the amount of light received is minimized after linearly polarized light has rotated, and a comparison step of comparing the standard rotation angle with the optical rotation.

[0023] According to the polarimeter calibration method of the present invention, by using a standard rotation angle of a polarizer measured by rotating the polarizer instead of a standard sample, calibration can be performed simply and accurately over a wide wavelength range, including wavelengths shorter than 546 nm. Furthermore, the polarimeter of the present invention does not require replacement of parts when performing calibration, and calibration can be performed using the same device configuration as when measuring a sample, allowing for quick and easy calibration.

[0024] In one aspect of the present invention, the difference between the standard rotation angle and the optical rotation is calculated as correction data, and if the correction data exceeds a threshold, the optical rotation is corrected using the correction data. According to this aspect, the difference between the standard rotation angle and the optical rotation is calculated as correction data, and if the correction data exceeds a threshold, the optical rotation is corrected using the correction data, thereby achieving more accurate measurement of the optical rotation.

[0025] The polarimeter calibration program disclosed in the present invention is a polarimeter calibration program for performing calibration using the rotation angle of a polarizer measured by rotating the polarizer. The polarimeter calibration program causes a computer to execute the following steps: a standard rotation angle acquisition process for rotating the polarizer without a sample or cell in the sample mounting section of the sample chamber and measuring the angle of rotation of the polarizer with an angle encoder to acquire a standard rotation angle; an optical rotation acquisition process for measuring the angle of rotation of the analyzer from the analyzer rotation position at which the amount of light received by the detection means is minimized to the analyzer rotation position at which the amount of light received is minimized after linearly polarized light has rotated and the amount of light received is no longer minimum; and a comparison process for comparing the standard rotation angle with the optical rotation.

[0026] The polarimeter calibration program of the present invention enables simple and precise calibration over a wide wavelength range, including wavelengths shorter than 546 nm, by using a standard rotation angle of a polarizer measured by rotating the polarizer instead of a standard sample. Furthermore, the polarimeter of the present invention does not require replacement of parts when performing calibration, and calibration can be performed using the same device configuration as when measuring a sample, allowing for quick and easy calibration. [Effects of the Invention]

[0027] The present invention can solve the above-mentioned problems of the prior art and achieve the above-mentioned object, and can provide a polarimeter, a polarimeter calibration method, and a polarimeter calibration program that do not require replacement of parts when performing calibration, and that can perform calibration quickly, simply, and accurately over a wide wavelength range including wavelengths shorter than 546 nm by using a standard rotation angle of a polarizer measured by rotating the polarizer instead of a standard sample. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram showing an embodiment of a conventional polarimeter. [Figure 2] FIG. 2 is a schematic diagram showing an embodiment of a conventional polarimeter during calibration. [Figure 3]FIG. 3 is a schematic diagram showing an example of the polarimeter of the first embodiment. [Figure 4] FIG. 4 is a diagram showing how the plane of polarization of linearly polarized light is rotated by the optical rotation of a sample. [Figure 5] FIG. 5 is a schematic diagram showing the relationship between the rotation angle and the light intensity in the detection means. [Figure 6] FIG. 6 is a diagram illustrating the principle of the symmetric angular oscillation method when there is no sample or cell in the sample placement section of the sample chamber. [Figure 7] FIG. 7 is a diagram illustrating the principle of the symmetric angular vibration method when a sample is placed in the sample placement section of the sample chamber. [Figure 8] FIG. 8 is a diagram showing an example of the hardware configuration of the polarimeter of the present invention. [Figure 9] FIG. 9 is a diagram showing an example of the functional configuration of a polarimeter according to the present invention. [Figure 10] FIG. 10 is a flowchart showing an example of the process flow of the polarimeter calibration method of the present invention. [Figure 11] FIG. 11 is a schematic diagram showing an example of a polarimeter according to the second embodiment. [Figure 12] FIG. 12 is a diagram illustrating a process for canceling out the fluctuation of the polarization plane of linearly polarized light in the polarimeter of the second embodiment. [Figure 13] FIG. 13 is a schematic diagram showing an example of a polarimeter according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Here, an embodiment of a polarimeter of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment described below. In each drawing, the same components are given the same reference numerals, and duplicate explanations may be omitted. Furthermore, the number, position, shape, etc. of each component are not limited to this embodiment, and the number, position, shape, etc. may be any number, position, shape, etc. that is preferable for implementing the present invention. Furthermore, the size relationships between each component in the following drawings may differ from those in reality.

[0030] (First embodiment) Fig. 3 is a schematic diagram of a polarimeter according to a first embodiment of the present invention. The polarimeter 200 in Fig. 3 includes a light source 101, an interference filter 102, a polarizer 103, a polarizer rotation means 104, an angle encoder 105, a modulation means 106, a sample chamber 107, a sample mounting section 107a, an analyzer 108, an analyzer rotation means 109, a detection means 110, and a control means 111. The arrows in Fig. 3 indicate the optical path, and the positions of the modulation means 106 and the sample chamber 107 may be reversed.

[0031] Light source 101 is an LED (Light Emitting Diode) that emits light in a wide wavelength range including wavelengths shorter than 546 nm, for example, wavelengths of 250 nm to 900 nm, and is supplied with lighting power from a lighting circuit (not shown). By using an LED as light source 101, it is possible to reduce the size and power consumption of the light source, and it is also possible to suppress the amount of heat generated in the polarimeter. As the light source 101, other than an LED, a sodium lamp, a halogen lamp, a mercury lamp, a laser, or the like can be used.

[0032] The interference filter 102 is a bandpass optical filter that passes light of the wavelength used to measure the optical rotation of the sample and blocks light of other wavelengths. The position where the interference filter 102 is provided is not particularly limited as long as it is in front of the analyzer 108 , and it may be between the polarizer 103 and the modulation means 106 , or before or after the sample chamber 107 .

[0033] The polarizer 103 is a polarizing plate that transmits only linearly polarized light components parallel to a single transmission axis, and converts the light from the light source 101 into linearly polarized light. The polarizer 103 may be, for example, a dichrome or a Glan-Taylor prism. The polarizer 103 is fixed to the polarizer rotation means 104, and during calibration, it is rotated by the polarizer rotation means 104. When the polarizer 103 is rotated, the direction of the transmission axis inherent to the polarizer 103 also rotates, and therefore the polarization plane of the linearly polarized light generated by the polarizer 103 also rotates. There are no particular limitations on the angle by which the polarizer 103 is rotated (polarizer rotation angle), and it can be appropriately selected depending on the optical rotation of the sample to be measured, etc. The rotation angle of the polarizer 103 can be accurately measured because an angle encoder is attached to the polarizer. The rotation angle measured by the angle encoder is a standard rotation angle that has been standardized with high accuracy. The polarizer rotating means 104 may be, for example, a rotating stage, a pulse motor, a hollow motor, or the like, and also includes a driver for driving and controlling the polarizer rotating means. An angle encoder 105 is attached to the polarizer 103 , and the polarizer rotating means 104 and the angle encoder 105 are connected to a control means 111 .

[0034] The angle encoder 105 is attached to the polarizer 103, measures the rotation angle of the polarizer 103 (i.e., the rotation angle of the polarization plane of the linearly polarized light emerging from the polarizer), and inputs a signal indicating the measured angle result to the control means 111. The angle encoder 105 is a rotary encoder that has been highly standardized using an angle measuring device (rotary encoder self-calibration device) certified as a specified standard instrument under the Metrology Act, ensuring traceability (20 AIST TODAY 2007-09. Techno-Infrastructure. "Supply and Development of Angle Standards"; https: / / www.aist.go.jp / Portals / 0 / resource_images / aist_j / aistinfo / aist_today / vol07_09 / vol07_09_p20.pdf; retrieved May 1, 2024). This ensures that the rotation angle of the polarizer measured by the angle encoder is also traceable.

[0035] The modulation means 106 is a Faraday coil that modulates the polarization plane of linearly polarized light. This Faraday coil is disposed at a position where the optical path passes through it, and is connected to an oscillator 119 that generates an alternating current. The Faraday cell serving as modulation means 106 has a configuration in which Faraday glass is incorporated into a Faraday coil, and is positioned inside the cell at a position where the optical path passes through it. When a current is supplied from oscillator 119, the Faraday cell generates a magnetic field inside, and the plane of polarization of linearly polarized light passing through the magnetic field rotates due to the Faraday effect. In this case, the rotation angle and direction of the plane of polarization of linearly polarized light passing through the Faraday cell fluctuates in accordance with the oscillating magnetic field, and the plane of polarization oscillates with an amplitude and frequency that correspond to the AC current.

[0036] The modulated linearly polarized light that has passed through the modulation means 106 is incident on the sample chamber 107 . A cell filled with a sample is placed in the sample placement section 107a in the sample chamber 107. The sample placement section 107a is placed at a position where the optical path passes, and during measurement, linearly polarized light is incident on the sample placed in the cell in the sample placement section 107a. During calibration, the sample placement section 107a is in a state where there is no sample or cell. Examples of the cell to be placed in the sample placement section 107a include a glass cell, a quartz cell, a flow cell, and a stainless steel (SUS) cell.

[0037] The linearly polarized light that has passed through the sample chamber 107 passes through an analyzer 108 . The analyzer 108 is a polarizing plate having a single transmission axis, and is rotated by an analyzer rotation means 109 and installed with the angle adjusted so that the transmission axis of the polarizer 103 and the transmission axis of the analyzer 108 are perpendicular to each other. Of the linearly polarized light incident on the analyzer 108, only linearly polarized light parallel to the transmission axis of the analyzer 108 is transmitted through the analyzer 108. The analyzer 108 is fixed to an analyzer rotation means 109, and the analyzer 108 rotates with the rotation of the analyzer rotation means 109. When the analyzer 108 rotates, the direction of the transmission axis inherent to the analyzer 108 changes, and the intensity of the linearly polarized light that passes through the analyzer 108 changes. The analyzer rotation means 109 is connected to a control means 111. The rotation angle of the analyzer 108 may be measured by, for example, an angle encoder attached to the analyzer, or may be measured by the number of pulse signals of a pulse motor which is the analyzer rotation means 109 . The analyzer rotating means 109 may include, for example, a rotating stage, a hollow motor, a pulse motor, etc., and also includes a driver for driving and controlling the analyzer rotating means.

[0038] The linearly polarized light that has passed through the analyzer 108 is incident on the detection means 110 . The detecting means 110 is composed of a light receiving element such as a photomultiplier tube (PMT) or a photodiode, and when linearly polarized light is detected, it outputs a detection signal that indicates the detected amount of linearly polarized light as a voltage. The intensity of the detection signal output by the detecting means 110 corresponds to the amount of linearly polarized light received by the detecting means 110. The detection means 110 is connected to a control means 111, and based on the detection signal obtained by the detection means 110, the control means 111 determines the optical rotation of the sample.

[0039] Control means 111 controls all operations of the polarimeter and is configured to include an input / output interface for inputting and outputting various signals, a calculation unit such as a microprocessor or integrated circuit that executes various types of calculation processing, a memory that stores temporary information necessary for signal processing, storage means that stores processing programs or data necessary for signal processing, input means, display means, output means, etc.

[0040] The polarimeter of this embodiment can be calibrated using a standard rotation angle of the polarizer 103 measured by the angle encoder 105 while rotating the polarizer 103 . When calibrating the polarimeter, the control means 111 rotates the polarizer 103 using the polarizer rotation means 104 without any sample or cell in the sample setting section 107a of the sample chamber 107, and performs a process of comparing the angle by which the polarizer 103 has rotated (the angle by which the polarization plane of linearly polarized light from the polarizer has rotated) with the standard rotation angle measured by the angle encoder 105, and the optical rotation angle, which is the angle by which the analyzer 108 has been rotated by the analyzer rotation means 109 from the rotation position of the analyzer 108 at which the amount of light received by the detection means 110 is minimum to the rotation position of the analyzer 108 at which the amount of light received is minimum when the linearly polarized light has rotated and the amount of light received is no longer minimum. Examples of comparison methods include a method of confirming that the standard rotation angle and the optical rotation coincide, a method of calculating the difference between the standard rotation angle and the optical rotation as correction data, and if the correction data exceeds a threshold, correcting the optical rotation using the correction data.

[0041] The control means 111 calculates the difference between the obtained standard rotation angle and the angle of rotation as correction data, and if the correction data exceeds a threshold value, the angle of rotation can be corrected using the correction data. The control means 111 compares the obtained standard rotation angle with the optical rotation value stored in advance by calibrating the polarimeter with a standard sample such as an aqueous sucrose solution or a quartz optical rotation plate. Since standard samples exist in the wavelength range of 500 nm to 800 nm, data management using standard samples can be performed by comparing the optical rotation value stored by calibrating the polarimeter with the standard sample with the standard rotation angle, further improving the reliability of the measurement data.

[0042] In the polarimeter 200 of the first embodiment, the transmission axis of the polarizer 103 and the transmission axis of the analyzer 108 are perpendicular to each other (see solid lines 103 and 108 in FIG. 4). In this state, the amount of light received by the detecting means 110 is minimized. First, when a cell filled with a substance having optical rotation is placed in the sample placement section 107a of the sample chamber 107, the polarization plane of the linearly polarized light from the polarizer 103 rotates by an amount α corresponding to the optical rotation of the sample. This state is shown by polarizer 103' in Figure 4, and the detection means 110 detects the brightness of the light corresponding to the rotation angle α. When the analyzer 108 is rotated by an amount α, the amount of light received by the detection means 110 is again minimized. The optical rotation of the sample can be determined from the rotation angle of the analyzer 108' at which this amount of received light is minimized.

[0043] Here, when the polarizer 103 is fixed in a certain direction and the analyzer 108 is rotated, if the rotation angle between the transmission axis of the polarizer 103 and the transmission axis of the analyzer 108 is θ, the relationship between the light intensity I and the rotation angle θ is as shown in FIG. 5, and is expressed by the following equation: I=cos 2 θ, and When the transmission axis of the polarizer 103 and the transmission axis of the analyzer 108 are perpendicular to each other, the following equation is satisfied: I=cos2 When the rotation angle θ changes around 90°, the change in light intensity I is small, making it difficult to perform highly accurate measurements. To solve this problem, the polarimeter of this embodiment employs a symmetric angular oscillation optical nulling method using a Faraday cell as modulation means 106. This symmetric angular oscillation method modulates the polarization plane and measures a signal related to the modulation frequency, making it possible to remove noise from other frequency signal components and enabling highly sensitive measurements.

[0044] First, when there is no sample or cell in the sample mounting section 107a of the sample chamber 107, the transmission axis of the polarizer 103 and the transmission axis of the analyzer 108 are perpendicular to each other, and the polarization plane of the linearly polarized light generated by the polarizer 103 oscillates left and right by ±δ degrees in a sine waveform over time due to the Faraday cell acting as modulation means 106 (Figure 6(a)). This is called modulation of the polarization plane of linearly polarized light. The change in light intensity I at this time is as shown in Figure 6(b). If the modulation frequency is fHz, then the light intensity I signal has a frequency of 2fHz as shown in Figure 6(b).

[0045] Next, when a cell filled with a sample having optical activity is placed in the sample placement section 107a of the sample chamber 107, the polarization plane of the linearly polarized light generated by the polarizer 103 rotates by the optical rotation α of the sample (Figure 7(a)). The change in light intensity I at this time results in a mixture of f Hz and 2f Hz signals, as shown in Figure 7(b). In other words, if the sample has optical activity, an optical signal with a frequency of f Hz is generated. This f Hz component optical signal is photoelectrically converted by a photomultiplier tube serving as detection means 110, then amplified and phase-detected, and input to analyzer rotation means 109, which rotates the analyzer 108. The analyzer 108 is then rotated until the f Hz signal disappears. Therefore, the analyzer 108 always stops in a state where no f Hz signal is generated, and this angle represents the optical rotation.

[0046] <How to calibrate a polarimeter> The polarimeter calibration method of the present invention performs calibration using the rotation angle of a polarizer measured by rotating the polarizer, and includes a standard rotation angle acquisition step, an optical rotation angle acquisition step, and a comparison step, and may further include other steps as necessary.

[0047] -Standard rotation angle acquisition process- In the standard rotation angle acquisition step, the polarizer is rotated without a sample or cell in the sample placement section of the sample chamber, and the angle by which the polarizer has rotated is measured with an angle encoder to obtain the standard rotation angle. The rotation angle of the polarizer is not particularly limited and can be appropriately selected depending on the optical rotation of the sample to be measured. The rotation angle of the polarizer can be accurately measured by attaching an angle encoder to the polarizer. The angle encoder is a rotary encoder whose traceability is guaranteed by a specific standard. This also guarantees the traceability of the rotation angle of the polarizer.

[0048] -Optical rotation acquisition process- The angle of rotation acquisition step measures the angle of rotation of the analyzer from the rotation position where the amount of light received by the detection means is minimum to the rotation position where the amount of light received is minimum when the linearly polarized light is rotated and the amount of light received is no longer minimum, thereby obtaining the angle of rotation. The rotation angle of the analyzer may be measured, for example, by an encoder attached to the analyzer, or may be measured based on the number of pulse signals of a pulse motor which is the analyzer rotating means.

[0049] -Comparison process- The comparison step compares the standard rotation angle obtained in the standard rotation angle obtaining step with the optical rotation obtained in the optical rotation obtaining step. Examples of comparison methods include a method of confirming that the standard rotation angle and the optical rotation coincide, a method of calculating the difference between the standard rotation angle and the optical rotation as correction data, and if the correction data exceeds a threshold, correcting the optical rotation using the correction data.

[0050] -Other processes- The other steps are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a management step, a storage step, a display step, and an output step.

[0051] (Polarimeter Calibration Program) The polarimeter calibration program of the present invention is a polarimeter calibration program for performing calibration using a rotation angle of a polarizer measured by rotating the polarizer, a standard rotation angle acquisition process in which the polarizer is rotated without a sample or cell being present in the sample placement section of the sample chamber, and the angle of rotation of the polarizer is measured with an angle encoder to acquire a standard rotation angle; an angle of rotation acquisition process for measuring the angle of rotation of the analyzer from a rotation position of the analyzer where the amount of light received by the detection means is minimum to a rotation position of the analyzer where the amount of light received is minimum when the linearly polarized light is rotated and the amount of light received is no longer minimum, thereby acquiring the angle of rotation; A comparison process is performed by the computer to compare the standard rotation angle with the angle of rotation.

[0052] The polarimeter calibration program of the present invention can be, for example, a program that causes a computer to execute the polarimeter calibration method of the present invention. Furthermore, preferred aspects of the polarimeter calibration program of the present invention can be, for example, the same as preferred aspects of the polarimeter calibration method of the present invention.

[0053] The polarimeter calibration program of the present invention can be created using various known programming languages ​​depending on the configuration of the computer system used and the type and version of the operating system.

[0054] The polarimeter calibration program of the present invention may be recorded on a recording medium such as an internal hard disk or an external hard disk, or may be recorded on a recording medium such as a CD-ROM (Compact Disc ROM), a DVD-ROM (Digital Versatile Disk ROM), an MO disk (Magneto-Optical disk), an SD card, or a USB memory (USB (Universal Serial Bus) flash drive). Furthermore, when the polarimeter calibration program of the present invention is recorded on the above-mentioned recording medium, it can be used directly or by installing it on a hard disk via a recording medium reader possessed by a computer system, as necessary. The polarimeter calibration program of the present invention may also be recorded in an external storage area (such as another computer) accessible from the computer system via an information and communication network. In this case, the polarimeter calibration program of the present invention recorded in the external storage area can be used directly or by installing it on a hard disk from the external storage area via an information and communication network, as necessary. The polarimeter calibration program of the present invention may be divided into programs for any desired processing and recorded on a plurality of recording media.

[0055] <Computer-readable recording medium> A computer-readable recording medium according to the present invention stores the polarimeter calibration program of the present invention. The computer-readable recording medium related to the present invention is not particularly limited and can be appropriately selected depending on the purpose, and examples include an internal hard disk, an external hard disk, a CD-ROM, a DVD-ROM, an MO disk, an SD card, and a USB memory. Furthermore, the computer-readable recording medium related to the present invention may be a plurality of recording media on which the polarimeter calibration program of the present invention is recorded in a divided form for each arbitrary process.

[0056] An example of the technology disclosed in the present invention will be described in more detail below using an example of the configuration of a polarimeter of the present invention and a flowchart. FIG. 8 shows an example of the hardware configuration of a polarimeter according to the present invention. In polarimeter 200, for example, control unit 201, main memory device 202, auxiliary memory device 203, I / O interface 204, communication interface 205, input device 206, output device 207, and display device 208 are connected via system bus 209.

[0057] The control unit 201 performs calculations (arithmetic operations, comparison operations, etc.), and controls the operation of hardware and software. The control unit 201 may be, for example, a CPU (Central Processing Unit), a part of a machine used in the polarimeter of the present invention, or a combination of these. The control unit 201 realizes various functions by executing a program (such as the polarimeter calibration program of the present invention) loaded into the main storage device 202 or the like. The processes performed by the standard rotation angle acquisition unit, the optical rotation angle acquisition unit, and the comparison unit in polarimeter 200 of the present invention can be performed by control unit 201.

[0058] The main memory device 202 stores various programs and also stores data necessary for executing the various programs. The main memory device 202 may include, for example, at least one of a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores various programs such as a BIOS (Basic Input / Output System), etc. There are no particular limitations on the ROM, and it can be selected appropriately depending on the purpose, and examples include mask ROM and PROM (Programmable ROM). The RAM functions as a working area in which various programs stored in, for example, the ROM or the auxiliary storage device 203 are deployed when they are executed by the control unit 201. There are no particular limitations on the RAM, and it can be selected appropriately depending on the purpose, and examples thereof include DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory).

[0059] The auxiliary storage device 203 is not particularly limited as long as it can store various types of information and can be appropriately selected depending on the purpose, and examples thereof include a solid state drive (SSD) and a hard disk drive (HDD). The auxiliary storage device 203 may also be a portable storage device such as a CD drive, a DVD drive, or a BD (Blu-ray (registered trademark) Disc) drive. The polarimeter calibration program of the present invention is stored in the auxiliary storage device 203, loaded into RAM (main memory) of the main storage device 202, and executed by the control unit 201.

[0060] The I / O interface 204 is an interface for connecting various external devices, and enables input and output of data from, for example, a CD-ROM, a DVD-ROM, an MO disk, an SD card, a USB memory, and the like.

[0061] The communication interface 205 is not particularly limited, and any known interface may be used as appropriate, such as a wireless or wired communication device.

[0062] There are no particular limitations on input device 206 as long as it can accept input of various requests and information for polarimeter 200 of the present invention, and any known device can be used as appropriate, such as a keyboard, mouse, touch panel, microphone, etc. Furthermore, if input device 206 is a touch panel (touch display), input device 206 can also serve as display device 208.

[0063] The output device 207 is not particularly limited, and any known device can be used as appropriate, such as a printer. The display device 208 is not particularly limited, and any known display device can be used as appropriate, such as a liquid crystal display or an organic EL display.

[0064] FIG. 9 shows an example of the functional configuration of a polarimeter according to the present invention. As shown in FIG. 9, polarimeter 200 includes a communication function unit 220, an input function unit 230, an output function unit 240, a display function unit 250, a storage function unit 260, and a control function unit 270.

[0065] The communication function unit 220, for example, transmits and receives various types of data to and from external devices. The input function unit 230 receives, for example, various instructions for the polarimeter 200. The input function unit 230 also receives, for example, information relating to the sample to be measured. The output function unit 240, for example, prints out the measurement data of the sample. The display function unit 250 displays, for example, the measurement data of the sample on a display.

[0066] The storage function unit 260 has, for example, a program storage DB 261 that stores various programs, and a data storage DB 262 that stores data from the standard rotation angle acquisition unit, the optical rotation angle acquisition unit, and the comparison unit.

[0067] Control function unit 270 has a standard rotation angle acquisition unit 271, an optical rotation angle acquisition unit 272, and a comparison unit 273. Control function unit 270 executes, for example, various programs stored in program storage DB 261 of storage function unit 260, and controls the operation of the entire polarimeter of the present invention.

[0068] The standard rotation angle acquisition unit 271 performs a process of rotating a polarizer when there is no sample or cell in the sample installation unit 107a of the sample chamber of the polarimeter, measuring the angle by which the polarizer has rotated with an angle encoder, and acquiring the standard rotation angle.

[0069] The optical rotation acquisition unit 272 performs a process of measuring the angle at which the analyzer is rotated from the rotation position at which the amount of light received by the detection means of the polarimeter is minimum to the rotation position at which the amount of light received is minimum when the linearly polarized light is rotated and the amount of light received is no longer minimum, and acquires the optical rotation. The comparison unit 273 performs a process of comparing the standard rotation angle with the angle of rotation, for example.

[0070] 10 is a flowchart showing an example of the process flow in the polarimeter calibration method of the present invention. The process flow in the polarimeter calibration method of the present invention will be described below with reference to FIGS. 3 and 9.

[0071] In step S11, the polarimeter 200 determines the initial rotation position of the analyzer 108 at which the intensity of the received light signal output by the detection means 110 is minimized when there is no sample or cell in the sample mounting portion 107a of the sample chamber 107, and then proceeds to S12.

[0072] In step S12, the control means 111 initializes the angle of the initial rotation position of the analyzer 108 by the analyzer rotation means 109, which has set the rotation position of the analyzer 108 to the initial rotation position, to an analyzer rotation angle of 0°, and then proceeds to S13.

[0073] In step S13, the control means 111 rotates the polarizer 103 using the polarizer rotation means 104, and when it determines the initial rotation position of the polarizer 103 at which the intensity of the received light signal output by the detection means 110 is minimized, the control means 111 proceeds to step S14. In step S13, when the polarizer 103 is in the initial rotation position, the transmission axis of the polarizer 103 is perpendicular to the transmission axis of the analyzer 108 (crossed Nicols position).

[0074] In step S14, the control means 111 initializes the angle of the initial rotation position of the polarizer 103 by the polarizer rotation means 104, which has set the rotation position of the polarizer 103 to the initial rotation position, and the angle of the angle encoder 105 to a polarizer rotation angle of 0°, and then proceeds to S15.

[0075] In step S15, the control means 111 rotates the polarizer 103 using the polarizer rotation means 104, and when the rotation is stopped, the process proceeds to S16. In step S15, the control means 111 may rotate the polarizer 103 by, for example, a predetermined rotation angle. The rotation of the polarizer 103 also rotates the polarization plane of the linearly polarized light generated by the polarizer.

[0076] In step S16, the angle encoder 105 measures the angle (standard rotation angle) by which the polarizer rotates from the rotation position of 0° rotation angle until it stops, and transmits the measured standard rotation angle to the control means 111, after which the processing proceeds to S17.

[0077] In step S17, the control means 111 rotates the analyzer 108 by the analyzer rotation means 109, and then stops the rotation, and moves the process to S18. In step S17, the control means 111 sequentially measures changes in the received light signal while rotating the analyzer 108. For example, by finding the rotation position at which the intensity of the received light signal becomes equal to or less than a predetermined threshold, the rotation position of the analyzer 108 at which the intensity of the received light signal becomes minimum is determined. In this state, the transmission axis of the polarizer 103 is perpendicular to the transmission axis of the analyzer 108 (crossed Nicols position).

[0078] In step S18, the control means 111 determines the angle of rotation from the angle of rotation of the analyzer 108, and then proceeds to step S19. In step S18, the angle of rotation of the analyzer 108 may be measured by an encoder attached to the analyzer, or may be calculated from the number of pulse signals of a pulse motor serving as the analyzer rotation means 109.

[0079] In step S19, the control means 111 compares the standard rotation angle obtained in step S16 with the angle of rotation obtained in step S18, and then ends this process. Methods for comparing the standard rotation angle and the optical rotation include, for example, a method of confirming that the standard rotation angle and the optical rotation match, a method of calculating the difference between the standard rotation angle and the optical rotation as correction data, and if the correction data exceeds a threshold, correcting the optical rotation using the correction data, etc. The obtained correction data is stored in a memory means in the control means.

[0080] After the calibration process is completed, the sample is placed in sample placement section 107a of sample chamber 107 and measured. The calibration process is performed for each polarimeter when the polarimeter is manufactured or inspected.

[0081] The polarimeter, polarimeter calibration method, and polarimeter program of the present invention enable simple and precise calibration over a wide wavelength range, including wavelengths shorter than 546 nm, without using a standard sample. Furthermore, the polarimeter of the present invention does not require replacement of parts when calibrating, and calibration can be performed using the same device configuration as when measuring a sample, allowing for quick and easy calibration.

[0082] (Second embodiment) When measuring the angle of rotation using a polarimeter over a long period of time, the balance position (the position where the amount of light received by the detection means is minimum) may change from the ideal state due to the effects of temperature changes, polarizer distortion, vibration, etc., causing fluctuations in the plane of polarization of linearly polarized light and potentially reducing measurement accuracy.The polarimeter of the second embodiment can further improve the measurement accuracy of the angle of rotation by correcting fluctuations in the plane of polarization of linearly polarized light using the polarization plane fluctuation correction means.

[0083] 11 is a schematic diagram showing an example of a polarimeter according to the second embodiment. In the second embodiment, the same components as those in the first embodiment already described are given the same reference numerals, and the description thereof will be omitted.

[0084] The polarimeter 300 of the second embodiment shown in FIG. 11 is the same as the polarimeter of the first embodiment shown in FIG. 3 except that the polarimeter 300 of the first embodiment shown in FIG. 3 has a second light source 112 and a polarization plane variation correction means 118 that corrects variations in the polarization plane of linearly polarized light. The polarization plane fluctuation correction means 118 is a means for correcting fluctuations in the polarization plane of linearly polarized light, which is obtained by converting incident light from the second light source 112 by the polarizer 103, and passing through the modulation means 106, the sample chamber 107 other than the sample placement section 107a, and the second analyzer 114, and then feeding back and controlling the detection signal detected by the second detection means 115 via the driver 116. The polarimeter 300 of the second embodiment further improves the measurement accuracy of the angle of rotation by including polarization plane fluctuation correction means 118 that corrects fluctuations in the polarization plane of linearly polarized light.

[0085] The second light source 112 may be, for example, a laser light source, and may be the same as the light source 101 of the polarimeter of the first embodiment. The second analyzer 114 can be the same as the analyzer 108 of the polarimeter of the first embodiment, except that it is fixed and does not rotate. By fixing the second analyzer 114, a second analyzer rotation means is not required, and only the intensity of the detection signal can be obtained from the second detection means. The second detecting means 115 may be the same as the detecting means 110 of the polarimeter of the first embodiment. The interference filter 102 is provided behind the sample chamber 107 and behind the mirror 113 so as not to cut off light from a second light source 112 for correcting fluctuations in the polarization plane of linearly polarized light. The Faraday cell serving as the modulation means 106 is configured with Faraday glass built into a Faraday coil, and periodically modulates the polarization direction of the incident light by applying an alternating current to the Faraday coil (see Figures 6 and 7 above).

[0086] In the second embodiment, the detection signal from second light analyzing means 115 has an alternating current (AC) component of 2f Hz, as in Fig. 6 above. When the polarization plane fluctuates due to the effects of temperature change, polarizer distortion, vibration, etc., a fluctuation of f Hz occurs, as in Fig. 7 above, and the detection signal becomes a signal in which 2f Hz and f Hz are mixed. A signal that cancels out the fluctuation component from this mixed detection signal is generated as a DC component by control means 111, and this generated DC component is combined with the AC component by driver 116 to obtain an AC component + DC component, and this AC component + DC component is applied to the Faraday cell serving as modulation means 106.

[0087] Specifically, as shown in FIG. 11 , linearly polarized light obtained by converting incident light from the second light source 112 using the polarizer 103 passes through the modulation means 106, the sample chamber 107 (excluding the sample mounting section 107a), and the second analyzer 114. A signal that cancels out the fluctuations in the detection signal detected by the second detection means 115 is generated as a DC component. The generated DC component is sent to the driver 116, which then combines it with an AC component to generate an AC component + DC component. This DC component + AC component is applied to the Faraday cell serving as the modulation means 106. Here, if there is no fluctuation in the polarization plane of the linearly polarized light, the signal applied to the Faraday cell serving as the modulation means 106 will be as shown by the solid line in FIG. 12 . On the other hand, if there is fluctuation in the polarization plane of the linearly polarized light, the signal detected by the second detection means 115 will contain the fluctuations. A signal that cancels out this fluctuations is generated as a DC component by the control means 111. This generated DC component is combined with an AC component by driver 116 to form an AC component + DC component, and as shown by the dotted line in Figure 12, a Faraday cell serving as modulation means 106 is driven by the DC component + AC component, which makes it possible to impart polarization rotation in addition to periodic modulation of the polarization direction, and to remove fluctuations in the polarization plane of linearly polarized light. As a result, fluctuations in the balance position (the position at which the amount of light received by the detection means is minimum) can be corrected, enabling more accurate measurement of the angle of rotation.

[0088] (Third embodiment) The polarimeter of the third embodiment corrects fluctuations in the polarization plane of linearly polarized light by a method different from that of the polarimeter of the second embodiment. 13 is a schematic diagram showing an example of a polarimeter according to the third embodiment. Note that in the third embodiment, the same components as those in the first and second embodiments already described are given the same reference numerals, and the description thereof will be omitted.

[0089] The polarimeter 400 of the third embodiment shown in FIG. 13 is similar to the polarimeter 300 of the second embodiment shown in FIG. 11 except that the light source 101 and the second light source 112 in the polarimeter 300 of the second embodiment shown in FIG. 11 are replaced by a single light source 101, and the polarizer 103 is replaced by a second polarizer 117.

[0090] As the light source 101, a light source similar to the light source in the first embodiment is used, and examples thereof include a polarized laser with a uniform polarization direction and a non-polarized laser. A Rochon prism or a Wollaston prism is used as the second polarizer 117. Of these, the Rochon prism is preferable. A Rochon prism consists of two prisms glued together so that their optical axes intersect perpendicularly. The optical axis of the input prism is parallel to the optical axis of the light entering the prism. The optical axis of the output prism is perpendicular to the optical axis of the light entering the prism. Therefore, when light passes through the first prism, the refractive index is the same regardless of its polarization state. However, when light enters the second prism, the refractive index differs depending on its polarization state. In this case, light with a polarization state that is the ordinary ray through the second prism has the same refractive index as the first prism, so it is not refracted at the prism boundary and passes through the prism. On the other hand, light with a polarization state that is the extraordinary ray through the second prism is refracted at the boundary between the two prisms and exits in a direction different from the incident direction. As a result, light with different polarization states can be separated by the different exit angles of the light from the Rochon prism. Therefore, by using a Rochon prism, the incident light from the light source 101 can be split into a first linearly polarized light and a second linearly polarized light having different optical axes.

[0091] The first linearly polarized light passes through the modulation means 106, the sample chamber 107, the interference filter 102, and the analyzer 108, and is used to measure the optical rotation of the sample. The second linearly polarized light passes through the modulation means 106, the sample chamber 107 other than the sample mounting portion 107a, and the second analyzer 114, and generates a signal as a DC component that cancels out the fluctuation in the polarization plane of the linearly polarized light from the detection signal containing the AC component detected by the second detection means 115 and the fluctuation in the polarization plane of the linearly polarized light.This generated DC component is combined with the AC component by the driver 116 to generate an AC component + DC component, and this AC component + DC component is used by the polarization plane fluctuation correction means 118, which drives a Faraday cell as the modulation means 106 to correct the fluctuation in the polarization plane of the linearly polarized light.

[0092] When light from light source 101 is incident on a Rochon prism serving as second polarizer 117 at an angle of 45°, it is split into linearly polarized light with a vertical optical axis and linearly polarized light with a horizontal optical axis. When light from light source 101 is incident on a Rochon prism serving as second polarizer 117 at an angle of approximately 10°, it is split into high-energy linearly polarized light and low-energy linearly polarized light. This is used in polarization plane variation correction means 118, which corrects variations in the polarization plane of the low-energy linearly polarized light, and the high-energy linearly polarized light can be used for sample measurement.

[0093] Like polarimeter 300 of the second embodiment, polarimeter 400 of the third embodiment has polarization plane fluctuation correction means 118 that corrects fluctuations in the polarization plane of linearly polarized light, thereby further improving the accuracy of measuring the angle of rotation. [Explanation of symbols]

[0094] 101 Light source 102 Interference Filter 103 Polarizer 104 Polarizer Rotation Means 105 Angle Encoder 106 Modulation means 107 Sample Room 107a Sample placement area 108 Analyzer 109 Analyzer rotation means 110 Detection means 111 Control means 112 Second light source 113 Mirror 114 Second analyzer 115 second detection means 116 Driver 117 Second polarizer 118 Polarization plane fluctuation correction means 119 Oscillator 200 Polarimeter 201 Control Unit 202 Main storage 203 Auxiliary storage device 204 I / O Interface 205 Communication Interface 206 Input Device 207 Output Device 208 Display device 209 System Bus 260 Memory Function Unit 261 Program storage database 262 Data storage DB 270 Control Function Unit 271 Standard rotation angle acquisition unit 272 Optical rotation acquisition section 273 Comparison Section 300 Polarimeter 400 Polarimeter

Claims

1. A polarimeter capable of performing calibration using a rotation angle of a polarizer measured by rotating the polarizer, A light source and a polarizer that converts the incident light from the light source into linearly polarized light parallel to a single transmission axis; a polarizer rotating means for rotating the polarizer around the transmission axis when calibrating the polarimeter; an angle encoder attached to the polarizer to measure the angle through which the polarizer is rotated; an analyzer that receives the linearly polarized light generated by the polarizer and transmits linearly polarized light parallel to a specific transmission axis; analyzer rotation means for rotating the analyzer to change the direction of the transmission axis; a detecting means for receiving and detecting the linearly polarized light transmitted through the analyzer; a control means for performing processing to rotate the polarizer by the polarizer rotating means when no sample or cell is present in the sample setting section of the sample chamber during calibration of the polarimeter, and to compare the angle of rotation of the polarizer with a standard rotation angle measured by the angle encoder, and the angle of rotation of the analyzer by the analyzer rotating means from the rotation position of the analyzer at which the amount of light received by the detection means is minimum to the rotation position of the analyzer at which the amount of light received is minimum when the linearly polarized light is rotated and the amount of light received is no longer minimum; A polarimeter comprising:

2. 2. The polarimeter according to claim 1, wherein the control means calculates a difference between the standard rotation angle and the angle of rotation as correction data, and when the correction data exceeds a threshold value, corrects the angle of rotation using the correction data.

3. 2. The polarimeter according to claim 1, wherein the standard rotation angle is a rotation angle of a polarizer measured using an angle encoder calibrated with an angle measuring device certified as a specific standard.

4. 2. The polarimeter of claim 1, wherein the angle encoder is a rotary encoder with guaranteed traceability.

5. The polarimeter according to claim 1, which is used for calibration in the wavelength range of 250 nm to 900 nm.

6. a second light source disposed near the light source; the linearly polarized light obtained by converting the incident light from the second light source by the polarizer passes through the modulation means, the sample chamber other than the sample placement portion, and the second analyzer, and the second detection means detects an AC component and a fluctuation in the polarization plane of the linearly polarized light, and the control means generates a DC component from the detection signal including the fluctuation, the DC component is generated by the control means, and the driver combines the generated DC component with the AC component to generate an AC component + DC component, and the modulation means is driven by the AC component + DC component to correct the fluctuation in the polarization plane of the linearly polarized light; 2. The polarimeter of claim 1, having

7. a second polarizer disposed in place of the polarizer and splitting the incident light from the light source into a first linearly polarized light and a second linearly polarized light; a measuring means for measuring the optical rotation of a sample by passing the first linearly polarized light through the modulation means, the sample mounting portion, the analyzer, and the detection means; 2. The polarimeter according to claim 1, further comprising: polarization plane variation correction means for correcting the variation in the polarization plane of the linearly polarized light by combining the generated DC component with the AC component by a driver to obtain an AC component plus a DC component and driving the modulation means with the AC component plus a DC component, the polarimeter comprising: a detection signal containing an AC component and a variation in the polarization plane of the linearly polarized light detected by the second detection means when the second linearly polarized light passes through the modulation means, the sample chamber other than the sample placement portion, and the second analyzer;

8. 8. The polarimeter of claim 7, wherein the second polarizer is a Rochon prism.

9. A polarimeter calibration method for performing calibration using a rotation angle of a polarizer measured by rotating the polarizer, comprising: a standard rotation angle acquisition step of rotating a polarizer without a sample or cell in a sample placement section of a sample chamber, and measuring the angle by which the polarizer has rotated with an angle encoder to acquire a standard rotation angle; an optical rotation acquisition step of measuring an angle of rotation of the analyzer from a rotation position of the analyzer where the amount of light received by the detection means is minimum to a rotation position of the analyzer where the amount of light received is minimum in a state where the linearly polarized light is rotated and the amount of light received is no longer minimum, thereby acquiring the optical rotation; a comparison step of comparing the standard rotation angle with the optical rotation angle; A method for calibrating a polarimeter, comprising:

10. 10. The polarimeter calibration method according to claim 9, further comprising: calculating a difference between the standard rotation angle and the angle of rotation as correction data; and correcting the angle of rotation using the correction data when the correction data exceeds a threshold value.

11. A polarimeter calibration program for performing calibration using a rotation angle of a polarizer measured by rotating the polarizer, a standard rotation angle acquisition process in which a polarizer is rotated without a sample or cell being present in the sample placement section of the sample chamber, and the angle of rotation of the polarizer is measured with an angle encoder to acquire a standard rotation angle; an angle of rotation acquisition process for measuring an angle of rotation of the analyzer from a rotation position of the analyzer where the amount of light received by the detection means is minimum to a rotation position of the analyzer where the amount of light received is minimum in a state where the linearly polarized light is rotated and the amount of light received is no longer minimum, thereby acquiring the angle of rotation; a comparison process for comparing the standard rotation angle with the angle of rotation; A polarimeter calibration program that causes a computer to execute the above steps.

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