Patent Publication Number: US-8982346-B2

Title: System and method for measuring the rotation angle of optical active substance

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application also claims priority to Taiwan Patent Application No. 101145046 filed in the Taiwan Patent Office on Nov. 30, 2012 the entire content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a system and method for rotation angle measurement, and more particularly, to a system and method for measuring rotation angle of optical active substances. 
     BACKGROUND 
     Although the pathogenesis of diabetes is complicated and still unclarified, it is generally regarded that the modern refine diet is a key factor causing the rapidly increasing worldwide prevalence of diabetes. It is an important task for people with diabetes to measure their glucose level regularly on a daily base. 
     A glucose meter is a common medical device for determining the approximate concentration of glucose in the blood. There are two types of glucose meters, which are the reflective glucose meter and the transmissive glucose meters. Nevertheless, both types of glucose meters are invasive devices, which require a skin puncture to get a sample of blood for glucose measurement. 
     It can be a torture mentally and physically for diabetic patients to perform the skin puncture multiple times on a daily base. Therefore, it is in need of a non-invasive glucose meter. 
     SUMMARY 
     In an exemplary embodiment, the present disclosure provides a system for measuring rotation angle of optical active substances, which comprises: a light source; a polarization generation unit; a polarization analyzing unit; and a signal generating unit, respectively and electrically coupled to the polarization generation unit and the polarization analyzing unit; wherein the light source is enabled to emit a beam toward the polarization generation unit for enabling the beam to be polarized into an incident polarized beam while being projected and traveled in an optical path passing through an optical active substance so as to be converted into a emerging beam; and the polarization analyzing unit is positioned to receive and analyze the emerging beam so as to generate a signal. 
     In another exemplary embodiment, the present disclosure provides a method for measuring rotation angle of optical active substances, which comprises the steps of: projecting a beam toward a polarization generating unit for converting the beam into an incident polarized beam; receiving a emerging beam so as to be used as basis for generating a signal; and converting the signal into a rotation angle data. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein: 
         FIG. 1  is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a first embodiment of the present disclosure. 
         FIG. 2  is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a second embodiment of the present disclosure. 
         FIG. 3  is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a third embodiment of the present disclosure. 
         FIG. 4  is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a fourth embodiment of the present disclosure. 
         FIG. 5  is a flow chart depicting the steps performed in a method for measuring rotation angle of optical active substances according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     Please refer to  FIG. 1 , which is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a first embodiment of the present disclosure. The measurement system shown in the embodiment of  FIG. 1  is used for measuring an optical active substance  15 , whereas the optical active substance  15  can be any glucose-containing substance, such as aqueous humor, blood, or skin tissue. In this embodiment, the system is used for measuring glucose level of aqueous humor, but is not limited thereby. 
     As shown in  FIG. 1 , the system for measuring rotation angle of optical active substances comprises: a light source  10 , a polarization generation unit  11 , a polarization analyzing unit  12 , a signal generating unit  13  and a signal processing unit  14 . 
     The light source  10  is used for emitting a beam  100 , whereas the light source in this embodiment can substantially be a light emitting diode, and the beam  100  can be a beam selected from the group consisting of: a continuous wave beam, an amplitude modulation beam, and a frequency modulation beam. 
     The polarization generating unit  11  is disposed on the optical path of the beam  100 , so that the beam  100  can be converting into an incident polarized beam  110  by the polarization generating unit  11 . 
     The optical active substance  15  is disposed on the optical path of the incident polarized beam  110 , so that the incident polarized beam  110  can be converting by the optical active substance  15  into a emerging beam  150 . 
     The polarization analyzing unit  12  is disposed on the optical path of the emerging beam  150 , by that the polarization analyzing unit  12  is able to generate a signal based upon the emerging beam  150 . 
     The signal generating unit  13  is respectively and electrically connected to the polarization generating unit  11  and the polarization analyzing unit  12 , by that the beam  100  of the light source  10  that is projected toward the polarization generation unit  11  is converted into an incident polarized beam  110 , and the polarization analyzing unit is enabled to generate a signal according to the emerging beam  150 . Moreover, the aforesaid electrical coupling is enabled by a means selected from the group consisting of: a wired connection means and a wireless connection means. 
     The processing unit  14  is provided for receiving the signal from the polarization analyzing unit  12  so as to generate a rotation angle data accordingly, and then the rotation angle data can be used in a calculation for obtaining a glucose level. In addition, the signal processing unit  14  is electrically connected to the signal generating unit  13  so as to control the signal generating unit  13 . In an embodiment, the signal processing unit can be a calculating unit or a cloud unit. 
     Please refer to  FIG. 2 , which is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a second embodiment of the present disclosure. Similarly, the system of the present embodiment is used for measuring an optical active substance  26 . 
     In the embodiment of  FIG. 2 , the measurement system comprises: a light source  20 , a polarization generation unit  21 , a beam splitting unit  22 , a polarization analyzing unit  23 , a signal generating unit  24  and a signal processing unit  25 . 
     Operationally, the light source  20  is used for emitting a beam  200 ; the polarization generating unit  21  is disposed on the optical path of the beam  200 , so that the beam  200  can be converting into an incident polarized beam  120  by the polarization generating unit  21 ; and the beam splitting unit  22  is disposed on the optical path of the incident polarized beam  210  for reflecting the travelling of the incident polarized beam  210  by an angle. It is noted that the beam splitting unit  22  can be a beam splitter. 
     Moreover, the optical active substance  26  is disposed on the optical path of the incident polarized beam  210  outputted from the beam splitting unit  22 . Accordingly, since the beam splitting unit  22  is arranged at a position between the optical active substance  26  and the polarization generation unit  21  whereas the optical active substance  26  is configured with an optical active interface  260 , such as the cornea, the incident polarized beam  210  can be reflected by the optical active interface  260  for converting the incident polarized beam  210  into a emerging beam  211  while projecting the emerging beam  211  toward the beam splitting unit  22 , and then to the polarization analyzing unit  23  so as to be used as a basis for generating a signal. 
     The signal generating unit  24  is respectively and electrically connected to the polarization generation unit  21  and the polarization analyzing unit  23 ; and the signal processing unit  25  is provided for receiving the signal from the polarization analyzing unit, whereas the signal processing unit  25  is electrically connected to the signal generating unit  24 . 
     Please refer to  FIG. 3 , which is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a third embodiment of the present disclosure. Similarly, the system of the present embodiment is used for measuring an optical active substance  36 . 
     In the embodiment of  FIG. 3 , the measurement system comprises: a light source  30 , a polarization generation unit  31 , a polarization analyzing unit  32 , a light detector  33 , a signal generating unit  34  and a signal processing unit  35 . 
     Operationally, the light source  30  is used for emitting a beam  300 ; the polarization generating unit  31  is disposed on the optical path of the beam  300  and is composed of a polarization element  310 , a first phase modulator  311 , and a second phase modulator  312 . It is noted that the polarization element  310  can be a polarizer or a Nicol prism that is designed to polarize a light into a polarized light; and each of the first and the second phase modulators  311 ,  312  is substantially a phase modulation device designed for altering the phase of a beam according to a specific pattern. 
     Thereby, the beam  300  is first being converted into a polarized beam by the polarization element; and then the polarized beam is projected to travel sequentially passing through the first phase modulator  311  and the second phase modulator  312  so as t be converted into an incident polarized beam  313 . 
     Moreover, the optical active substance  36  is disposed on the optical path of the incident polarized beam  313 , by that the incident polarized beam  313  is converted into a emerging beam  360 . In addition, the polarization analyzing unit  32  is disposed on the optical path of the emerging beam  360  and is composed of a third phase modulator  320 , a fourth phase modulator  321  and an analyzer  322 . Accordingly, the emerging beam  360  is projected to travel sequentially passing through the third phase modulator  320 , the four phase modulator  321  and the analyzer  322 . It is noted that the analyzer  322  can be a polarizer provided for determining whether a beam incident thereto is a polarized beam. In this embodiment, the emerging beam  360  is determined by the analyzer  322  to be a polarized beam. 
     The light detector  33  is disposed on the optical path of the emerging beam  360  after being projected out of the polarization analyzing unit  32 , and the light detector  33  is used for generating a signal based upon the emerging beam  360 . 
     The signal generating unit  34  is respectively and electrically connected to the first phase modulator  311 , the second phase modulator  312  so as to control the operations of those phase modulators  311 ,  312 ,  320 , and  321 ; and the signal processing unit  35 , that is electrically connected to the signal generating unit  34 , is provided for receiving the signal from the light detector  33  to be used as a base for generating a rotation angle data, whereas the rotation angle data is used in a calculation for obtaining a glucose level. 
     Please refer to  FIG. 4 , which is a schematic diagram showing a system for measuring rotation angle of optical active substances according to a fourth embodiment of the present disclosure. Similarly, the system of the present embodiment is used for measuring an optical active substance  46 . 
     In the embodiment of  FIG. 4 , the measurement system comprises: a light source  40 , a polarization generation unit  41 , a polarization analyzing unit  42 , a light detector  43 , a signal generating unit  44  and a signal processing unit  45 . 
     Operationally, the light source  40  is used for emitting a beam  400 ; the polarization generating unit  41  is disposed on the optical path of the beam  400  and is composed of a polarization element  410 , a phase modulator  411 , and a wave plate  412 . It is noted that the polarization element  410  is designed to polarize a light into a polarized light; and the phase modulators  411  is substantially a phase modulation device designed for altering the phase of a beam according to a specific pattern. In this embodiment, the phase modulation device is a device selected from the group consisting of: a liquid crystal retardation modulator, a photoelastic modulator, and a Babinet-Soleil compensator. In addition, the wave plate  412  is used for causing a phase difference to a beam travelling passing therethrough, and in this embodiment, the wave plate  412  is substantially a quarter-wave plate. 
     As shown in  FIG. 4 , the beam  400  is projected passing sequentially through the polarization element  410 , the phase modulator  411  and the wave plate  412  so as to be converted into an incident polarized beam  413 . 
     In a condition when the phase modulator  411  is configured with an axle, the polarization element  410  should be arranged for allowing an included angle ranged between 45 degrees and −45 degrees to be formed between the axle of the polarization element  410  and the axle of the phase modulator  411 . 
     In a condition when the wave plate  412  is configured with an axle, the phase modulator  411  should be arranged for allowing an included angle ranged between 45 degrees and −45 degrees to be formed between the axle of the phase modulator  411  and the axle of the wave plate  412 . 
     Moreover, the optical active substance  46  is disposed on the optical path of the incident polarized beam  413 , by that the incident polarized beam  413  is converted into a emerging beam  460 . 
     In addition, the polarization analyzing unit  42  is disposed on the optical path of the emerging beam  460  and is composed of a wave plate  420 , a phase modulator  421  and an analyzer  422 . In this embodiment, the wave plate  420  is a quarter-wave plate, and the analyzer  422  is a polarizer. Accordingly, the emerging beam  460  is projected to travel sequentially passing through the wave plate  420 , the phase modulator  421  and the analyzer  422 . 
     The light detector  43  is disposed on the optical path of the emerging beam  460  after being projected out of the polarization analyzing unit  42 , and the light detector  43  is used for generating a signal based upon the emerging beam  460 . 
     The signal generating unit  44  is respectively and electrically connected to the phase modulators  411 ,  412  so as to control the operations of those phase modulators  411 ,  412 ; and the signal processing unit  45 , that is electrically connected to the signal generating unit  44 , is provided for receiving the signal from the light detector  43  to be used as a base for generating a rotation angle data. 
     Please refer to  FIG. 5 , which is a flow chart depicting the steps performed in a method for measuring rotation angle of optical active substances according to an embodiment of the present disclosure. As shown in  FIG. 5 , the measurement method comprises the following steps:
         S 1 : enabling a light source to emit a beam, whereas the beam is elected from the group consisting of: a continuous wave beam, an amplitude modulation beam, and a frequency modulation beam, and is characterized by a wavelength ranged between 600 nm and 1700 nm;   S 2 : converting the beam into an incident polarized beam using components described in the measurement systems of the aforesaid first, second, third and fourth embodiments, in that the beam is polarized by a polarization generation unit into an incident polarized beam while allowing the incident polarized beam to be projected toward an optical active substance, such as an eyeball, a finger, an ear, an so on, and as the incident polarized beam is featured by a specific wavelength, it is free from interference of substances other than the target optical active substance;   S 3 : enabling the optical active substance to convert the incident polarized beam into a emerging beam, and then by the use of components described in the aforesaid first and second embodiments, the emerging beam is received by the polarization analyzing unit so as to be used as a base for generating a signal; or by the use of components described in the aforesaid third and fourth embodiments, the emerging beam is projected passing sequentially through the polarization analyzing unit and the light detector so as to be used for generating a signal;   S 4 : enabling a signal processing unit to receive the signal to be applied in a Stokes parameter analysis or a normalization analysis for generating a rotation angle data. In an embodiment when the optical active substance is an eyeball, the rotation angle data can be used in a calculation for obtaining blood glucose level.       

     In the proceeding of the step S 3  and using the measurement system described in the fourth embodiment of  FIG. 4  for illustration, the rotation angle data can be represented by the following formula:
 
 S=[r   1 ( t ), r   2 ( t )]=| A*M   2   [r   2 ( t )]* Q   2   *R*Q   1   *M   1   [r   1 ( t )]* P|   2  
 
     wherein,
         M 1  is the phase modulator  411 ;   r 1 (t) is the phase of the phase modulator  411 ;   M 2  is the phase modulator  421 ;   r 2 (t) is the phase of the phase modulator  411 ;   [r 1 (t), r 2 (t)] represents a phase-time function;   R is the optical active substance  46 ;   Q 1  is the wave plate  412 ;   Q 2  is another wave plate  42 ; and   A represent the electric field of the polarization element  422 .       

     For instance, when the axle of the polarization element  410  is orientated at 0 degree, the axle of the phase modulator  411  will be orientated at 45 degrees, the axles of the wave plates  410  and  412  will be orientated at 90 degrees, and the axle of the phase modulator  421  will be orientated at 90 degrees. 
     If the signal generated from the light detector  42  is a signal of light intensity, the light intensity can be represented as I[r 1 (t),r 2 (t)]. Thus, the rotation angle data can be represented as 
     
       
         
           
             
               
                 I 
                 ⁡ 
                 
                   [ 
                   
                     
                       
                         r 
                         1 
                       
                       ⁡ 
                       
                         ( 
                         
                           t 
                           2 
                         
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                       ⁡ 
                       
                         ( 
                         
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                         ( 
                         
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                         r 
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                       ⁡ 
                       
                         ( 
                         
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     In the aforesaid formula, the numerators on the left are corresponding to the numerators on the right, while the nominators numerators on the right are corresponding to a theoretical function at time t 2 ; and the denominators on the left are corresponding to the denominators on the right, while the denominators on the right are corresponding to a theoretical function at time t 1 . Thus, it can be used in a calculation of rotation angle data. 
     When a Stokes parameter analysis is applied in a calculation of rotation angle data, it is performed using the following formulas: 
     
       
         
           
             
               
                 
                   
                     
                       
                         
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                   Formula 
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                     . 
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
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     The S└r 1 (t),0°┘+S└r 1 (t),180°┘ of formula 1 and the S└r 1 (t),90°┘+S└r 1 (t),270°┘ of formula 2 can be treated as representative stroke parameter S 0 , whereas the stroke parameter of formula 1 is referred as S 1  and the stroke parameter of formula 2 is referred as S 2 . Thereby, an optimal solution for the calculation of rotation angle data can be obtained by the combination of formula 1 and formula 2. 
     To sum up, the present disclosure provide a method and a system for projecting a beam of specific wavelength to a polarization generation unit so as to be polarized into an incident polarized beam, and then enabling the incident polarized beam to shine on and travel passing through an optical active substance so as to form a emerging beam. Thereafter, the emerging beam is projected on a polarization analyzing unit to be used as a basis for generating a signal of light intensity while allowing the signal to be analyzed by a means of Stokes parameter analysis or a reflection rate analysis so as to obtain a rotation angle data. Then the rotation angle data is applied in a calculation for obtaining a glucose level. The method and system of the present disclosure measures a rotation angle of an optical active substances, and then applies the rotation angle in a calculation for obtain the glucose level of the optical active substance, and as a consequence, the measurement method and system are non-invasive measurement method and system. 
     With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the disclosure, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present disclosure.