KR101959990B1 - Apparatus and method for measuring refractive index - Google Patents

Abstract

The present invention uses a method of calculating a refractive index by calculating the amount of transmitted light from a light amount distribution detected by a photoelectric sensor. According to the present invention, the necessity of accurately finding the total reflection point in the light quantity distribution of reflected light can be eliminated, the problem of variation in the amount of light emitted from a light source and the influence of external light can be overcome, and the accuracy of the refractive index measurement can be increased. To this end, a refractive index measuring device according to the present invention comprises: a light source which irradiates an interface between a sample and a prism with light; a photoelectric sensor in which a plurality of photovoltaic cells for receiving light reflected from the interface and generating an electrical signal corresponding to the amount of received light are arranged in one direction; and a calculation means for calculating a refractive index characteristic point by utilizing the distribution of the amount of light according to the position of a light cell in the photoelectric cell array direction, and calculating the refractive index of the sample from the calculated refractive index characteristic point.

Description

[0001] Apparatus and method for measuring refractive index [0002]

The present invention relates to an apparatus and a method for measuring a refractive index of a solution or the like using the total reflection principle.

Recently, there has been a growing interest in health problems due to the ingestion of food, and it is necessary to accurately measure the content of sugar and saline contained in foods.

As a method of measuring salinity or sugar content, an optical method using a refractive index is mainly used. In the optical method, the photoelectric sensor detects light reflected from the interface between the prism and the sample, and the refractive index of the sample is calculated by detecting the total reflection position in the reflected light. That is, attempts are made to find out the refractive index of the sample by finding the point at which the total reflection starts from the distribution of the reflected light detected by the photoelectric sensor.

However, the light intensity distribution graph of the reflected light detected by the actual photoelectric sensor has a problem that the total reflection point can not be accurately grasped like the theoretical light intensity distribution graph. As a result, a measurement error is generated in the optical refractive index measuring apparatus using the total internal reflection principle.

In addition, the optical refractive index measuring apparatus detects the light reflected from the interface between the sample and the prism to the photoelectric sensor and calculates the refractive index from the light amount distribution of the reflected light. In the photoelectric sensor, not only the reflected light reflected from the interface but also the external light A detection error due to external light may also occur.

As described above, in the optical refractive index measuring apparatus using the conventional total reflection principle, it is difficult to accurately detect the total reflection point and an error may occur in the measurement of the refractive index due to the influence of external light.

The problem of the present invention is to improve the accuracy of the refractive index measurement in the optical refractive index measuring apparatus using the total reflection principle.

Specifically, the present invention solves the problem of difficulty in finding the total reflection point in the light amount distribution of the reflected light, the problem of the intensity deviation of the light emitted from the light source, and the accuracy of the refractive index measurement by overcoming the problem caused by the external light.

According to an aspect of the present invention, there is provided an illumination optical system including a light source for irradiating light to an interface between a sample and a prism; A photoelectric sensor in which a plurality of photoelectric cells receiving light reflected at the interface and generating an electric signal corresponding to a light amount of the received light are arranged along one direction; And calculation means for calculating a refractive index characteristic point by using a distribution of light quantity in accordance with the position of the light ray cell in the direction of arrangement of the photoelectric cells and calculating a refractive index of the sample based on the calculated refractive index characteristic point Refractive index measuring device.

In the refractive index measurement apparatus, the refractive index characteristic point may be calculated based on the amount of transmitted light.

Wherein the refractive index characteristic point is calculated using a temporary characteristic point, and the refractive index characteristic point is calculated based on a result of calculating the temporary characteristic point at least twice while changing the range of the target cell for calculating the temporary characteristic point. The refractive index characteristic point can be calculated.

In the refractive index measurement apparatus, the range of the target cell for calculating the temporary characteristic point is set to be centered on the center cell, and the range of the target cell is changed by changing the number of target cells Can be changed.

In the refractive index measuring apparatus, the center cell calculates a magnitude in which the light quantity of each photoelectric cell increases along the array direction of the photoelectric cells with respect to the light quantity of the immediately preceding photoelectronic cell, and the photoelectric cell, It can be set as a center cell.

In the refractive index measurement apparatus, the temporary characteristic point may be calculated using the following equation.

(Equation)

Here, a is the start position of the photoelectric cell used for calculating the temporary characteristic point, n is the number of photoelectric cells to be used for calculation of the temporary characteristic point, X _i is the position value of the i th photoelectric cell, Y _i is the light amount .

In the refractive index measurement apparatus, the refractive index characteristic point may be calculated using the following equation.

(Equation)

(2j + 1) is the number of cells to be used in the calculation of the temporary characteristic point, d is the number of times of calculation of the temporary characteristic point, b is a variable designating the starting position (mb) of the cell used when calculating the first temporary characteristic point, and X _m is the center cell position value.

According to another aspect of the present invention, there is provided a refractive index measurement method performed by a refractive index measurement apparatus including a photoelectric sensor in which a plurality of photoelectric cells are arranged in one direction, Calculating a refractive index characteristic point based on a light amount distribution according to a position of the photoelectric cell; And calculating a refractive index of the sample from the calculated refractive index characteristic point.

In the refractive index measurement method, the step of calculating the refractive index characteristic point may calculate the amount of transmitted light based on the amount of light detected by the photoelectric sensor and calculate the index of refraction characteristic based on the calculated amount of transmitted light.

In the refractive index measurement method, the step of calculating the refractive index characteristic point may include: calculating a temporary characteristic point by a predetermined number of times using the amount of transmitted light while changing the range of the target photoelectric cell; And calculating the refractive index characteristic point based on the calculated temporary characteristic points.

In the method of measuring the refractive index, the range of the target photoelectric cell is set centered on the center cell, and the range of the target photoelectric cell can be changed by changing the number of the target photoelectric cells while maintaining the center cell have.

In the refractive index measurement method, the center cell calculates a magnitude in which the light quantity of each photoelectric cell increases along the array direction of the photoelectric cells with respect to the light quantity of the immediately preceding photoelectric cell, and the photoelectric cell, It can be set as a center cell.

According to the present invention, the accuracy of refractive index measurement can be improved in an optical refractive index measurement apparatus. Specifically, according to the present invention, the problem of difficulty in finding the total reflection point in the light amount distribution of the reflected light, the problem of the intensity deviation of the light emitted from the light source, and the problem of the external light can be overcome and the accuracy of the refractive index measurement can be improved.

1 shows an apparatus for measuring a refractive index according to an embodiment of the present invention.
Fig. 2 illustrates a photoelectric sensor of a refractive index measuring apparatus.
3 illustrates the theoretical light amount distribution and the actual light amount distribution detected by the photoelectric sensor.
4 is a view for explaining the principle of measuring a refractive index according to an embodiment of the present invention.
5 is a view for explaining the principle of calculating a refractive index characteristic point according to an embodiment of the present invention.
6 is a view for explaining a refractive index measurement procedure according to an embodiment of the present invention.
7 is a view for explaining a refractive index measurement procedure according to another embodiment of the present invention.
8 is a flowchart for explaining a procedure for calculating the refractive index characteristic point.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected."

FIG. 1 shows an apparatus 100 for measuring a refractive index according to an embodiment of the present invention. The refractive index measurement apparatus 100 may include a light source 110, a prism 120, a photoelectric sensor 130, an arithmetic means 140 and a barrier 150.

The sample S may be dropped onto one surface of the prism 120 and a region formed by the barrier ribs 150. The light source 110 can irradiate light to the interface between the sample S and the prism 120. Part of the incident light Li incident on the interface becomes transmitted light Lt passing through the boundary surface and the specimen S and part of the incident light is reflected at the interface and becomes reflected light Lr traveling to the photoelectric sensor 130. [

The photoelectric sensor 130 can detect the reflected light Lr and provide the result to the calculating means 140. [ To this end, the photoelectric sensor 130 may be arranged along one direction with a plurality of photoelectric cells receiving the light Lr reflected at the interface and generating an electric signal corresponding to the light quantity of the received reflected light Lr. It is preferable that the direction in which the photoelectric cells are arranged is arranged so as to be able to detect the distribution of the reflected light Lr according to the incident angle [theta] of the incident light Li from the light source 110. [

 The calculation means 140 can calculate the refractive index of the sample S from the light amount distribution data detected by the photoelectric sensor 130. [

The principle of the refractive index measuring apparatus 100 for detecting the refractive index of the sample S will be described. Incident light Li emitted from the light source 110 and incident on the prism 120 is incident with an incident angle?. The angle of incidence can be defined as the angle between the reference line perpendicular to the interface between the sample S and the prism 120 and the incident light Li. Whether or not some of the incident light Li is reflected at the interface and becomes the reflected light Lr can be changed according to the refractive index and the incident angle? Of the sample S and the prism 120. The transmitted light Lt is increased and the reflected light Lr is decreased and the reflected light Lr is increased as the angle of incidence is increased and becomes equal to or greater than the critical angle at which total reflection occurs, And all the incident light Li is reflected by the reflected light Lr. The critical angle at which total reflection occurs may vary depending on the refractive index of the sample S and the refractive index of the prism 120. The photoelectric sensor 130 can use a structure in which a plurality of photoelectric cells are arranged along one direction so as to detect the reflected light Lr and detect the light amount distribution according to the incident angle [theta]. The photoelectric sensor 130 provides the light amount information of the reflected light Lr detected in each of the photoelectric cells arranged in one direction to the calculating means 140. The calculating means 140 calculates the light amount of the reflected light Lr The refractive index of the sample S can be calculated from the light amount distribution data.

Fig. 2 illustrates a photoelectric sensor 130. Fig. A plurality of photoelectric cells 131 may be arranged in one direction (the lateral direction in Fig. 2) in the photoelectric sensor 130. [ 2, the photoelectric sensor 130 is composed of P photoelectric cells 131 from 1 to P times. Each photoelectric cell 131 can receive the light reflected at the interface and generate an electrical signal corresponding to the amount of light of the received reflected light. The photoelectric sensor 130 may include several tens of photoelectric cells 131. In FIG. 2, the photoelectric cell position value is displayed together with the photoelectric cell number. A value including the position information of each photoelectric cell 131 may be used as the position value of the photoelectric cell 131. When the plurality of photoelectric cells 131 are arranged at the same interval, the photoelectric cell number may be used as the photoelectric cell position value. However, if the plurality of photoelectric cells 131 are not arranged at the same interval, The position values may be used separately. The positional value of the photoelectric cell 131 is required for calculating the refractive index characteristic point, and details of the calculation of the refractive index characteristic point will be described in detail below.

3 illustrates the theoretical light amount distribution and the actual light amount distribution detected by the photoelectric sensor. In the graph of FIG. 3, the X axis represents the position of the photoelectric cell, and the Y axis represents the continuous light intensity of the light received by each photoelectric cell. The theoretical light intensity distribution curve 310 shows that the amount of received light increases as the position of the photoelectric cell increases, and all the incident light from the total reflection point becomes the reflected light, so that the amount of light remains constant. However, the light intensity distribution curve 320 detected by the actual photoelectric sensor is similar to the theoretical light intensity distribution curve 310 in that the amount of received light increases as the position of the photoelectric cell increases, but the light intensity distribution curve 320 continuously increases in the vicinity of the total reflection point Since it has a smooth curve shape, it may not be easy to find an accurate total reflection point. The optical refractive index measuring apparatus of the total reflection type is a method of calculating the refractive index by estimating the point where the total reflection occurs from the light amount distribution curve of the reflected light. When the light amount distribution curve 320 has a shape as shown in FIG. 3 (b) It is difficult to accurately determine the refractive index. Therefore, the calculated refractive index may include an error.

In the present invention, a method of detecting a refractive index of a sample by another method instead of searching for a total reflection point is described with reference to FIGS. 4 and 5, recognizing that finding the total reflection point may involve an error .

Referring to FIG. 4, it can be understood that the rectangular region formed by the position value (X _p ) of the last photoelectric cell and the light amount (Y _p ) at this time is divided into two regions by the light amount distribution curve. Part of the incident light from the light source is transmitted light that is transmitted through the sample and the remaining part is reflected light and is detected by the photoelectric sensor. In addition to reflected light, external light will also be detected in the light detected by the photoelectric sensor. That is, the lower region of the light intensity distribution curve can be understood as the sum of the reflected light and the external light as the sum of the amounts of light detected by the respective photoelectric cells. On the other hand, the upper region (hatched region in FIG. 4) of the light intensity distribution curve can be understood as the light amount of the transmitted light.

When the critical angle at which the total reflection occurs varies depending on the refractive index characteristics of the sample, a point indicated by the 'total reflection position' in the light amount distribution curve of FIG. 4 is moved. As a result, the upper area (transmitted light amount) The area (detection light amount) will be changed. That is, if the refractive index characteristic of the sample is changed, the total reflection position at the interface between the specimen and the prism changes, thereby changing the amount of light to be transmitted and the amount of light to be detected. Therefore, if any one of the transmitted light amount or the detected light amount is used, The refractive index can be determined.

The refractive index of the sample can be obtained by using any one of the transmitted light amount and the detected light amount. However, as mentioned above, the detected light amount detected by the photoelectric sensor is detected not only by the reflected light but also by the external light introduced from the outside. Since it is not easy to remove the influence of external light from the light detected by the photoelectric sensor and accurately detect the amount of reflected light, it is preferable to use the light amount of transmitted light rather than to use the detected amount of light. That is, since the transmitted light amount information shaded in FIG. 4 is information excluding the influence of external light, the error caused by the influence of external light can be reduced.

Next, a refractive index measurement method according to an embodiment of the present invention will be described in detail with reference to FIG. In the present invention, as described above, the refractive index is measured using the amount of transmitted light (the area of the upper area of the light intensity distribution curve). To this end, the refractive index characteristic point is first calculated using the amount of transmitted light, A method of calculating the refractive index of the sample can be used.

In the embodiment of the present invention, the following equation (1) can be used to calculate the refractive index characteristic point (X _c ).

(1)

Here, a is the start position of the photoelectric cell used for calculating the refractive index characteristic point, n is the number of photoelectric cells to be used for calculating the refractive index characteristic point, X _i is the position value of the i th photoelectric cell, Y _i is the light amount .

Y _i can be the amount of light measured in the photoelectric cell, but it is also possible to use a result obtained by filtering or calculating the light amount measured in the photoelectric cell. As an example of the arithmetic processing, the average value of the adjacent cell (s) can be used. For example, the light amount of any photoelectric cell may be the average value of the previous cell (s) and the subsequent cell (s). In this case, there is an advantage that the influence of noise and the like can be reduced. The number of cells used to calculate the average using adjacent cells may be set to three, five, and so on.

는 X_a로부터 X_{a +n}까지의 범위에서 광량 분포 곡선의 아래 부분의 면적이다(시그마 기호 내부는 도 5에 예시된 바와 같이 X_i, Y_i, Y_{i +1} 및 X_{i +1}의 네 꼭지점이 형성하는 사각형의 면적이다). 즉, 수학식 1에서 분자는 Y_{a +n}과 X_{a +n}이 형성하는 큰 사각형의 면적에서 Y_a와 X_a가 형성하는 작은 사각형의 면적 및 X_a로부터 X_{a +n}의 범위에서 광량 분포 곡선의 아래 부분의 면적을 뺀 것이므로, 광량 분포 곡선의 위쪽 면적(도 5에서 빗금으로 표시한 영역)을 계산한 것으로서 투과광의 광량을 의미한다.The first item (Y _{a + n} X _{a + n} ) is the area of a large square formed by Y _{a + n} and X _{a + n} , and the second item (Y _a · X _a ) is the area of a small square formed by Y _a and X _a , and the third item

Is the area of the lower portion of the light intensity distribution curve in the range from X _a to X _{a + n} (the sigma sign is the area of X _i , Y _i , Y _{i +1,} and X _{i +1} as illustrated in FIG. 5) The area of the rectangle formed by the vertex). That is, the numerator in Equation 1 represents the area of a small square formed by Y _a and X _a in the area of a large rectangle formed by Y _{a + n} and X _{a + n} , and the area of the light amount distribution in the range of X _a to X _{a +} Is calculated by subtracting the area of the lower portion of the curve from the upper area of the light amount distribution curve (the area indicated by hatching in Fig. 5), which means the light amount of the transmitted light.

In the above equation (1), (X _{i +1} - X _i ) means the interval between the photoelectric cells. When a plurality of photoelectric cells are arranged at equal intervals, (X _{i +1} - X _i ) can be regarded as a constant. When the photoelectric cells are at the same interval, the photoelectric cell number can be used as the photoelectric cell position value. In this case, (X _{i +1} - X _i ) becomes 1, so the above Equation 1 can be simply expressed as Equation have.

(2)

Next, the denominator item of Equation (1) will be described. The light amount of the transmitted light calculated through the numerator of Equation (1) can be changed according to the intensity of light emitted from the light source. That is, even if the critical angle is the same using the same sample, the light amount of the transmitted light calculated through the numerator of Equation 1 will also vary if the light amount irradiated by the light source is changed. It is preferable that the light source does not cause an error due to a change in the amount of light emitted from the light source since the light amount is likely to change due to deterioration over time. The division of the transmitted light amount calculated through the numerator by the denominator (Y _{a + n} - Y _a ) in the above Equation (1) is intended to accurately detect the refractive index without being influenced by the light amount deviation of the light source.

(Y _{a + n} - Y _a ) of the denominator is calculated by subtracting Y _a, which is the amount of light detected by the photoelectric cells at the start position, from Y _{a + n} , which is the light amount detected by the photoelectric cells at the last position among the n photoelectric cells included in the calculation . When the photoelectric cell (X _a) in the starting position the light from the light source is mostly transmitted through the reflection light is almost no influence of the light source is minimal, while the external light will be mainly detected, in the case of the photoelectric cell of the last position is little light from the light source Most of the reflected light is detected as well as the external light is detected. Therefore, the difference in the light quantity of the photoelectric cells at two positions corresponds to the light quantity of the incident light from the light source.

Equation 1 is obtained by dividing the amount of transmitted light by the amount of incident light emitted from the light source and can be understood as meaning the amount of transmitted light normalized with respect to the amount of incident light. That is, when the refractive index of the sample is changed, the point at which the total reflection occurs varies, and thus the amount of transmitted light varies. The refractive index characteristic point X _c calculated by Equation 1 is obtained by dividing the amount of transmitted light by the amount of incident light The refractive index of the sample is not only reflected by the refractive index characteristics of the sample but also by the influence of the external light and the light quantity variation of the light source.

The range of the photoelectric cells used for calculating the refractive index characteristic point can be set to include n photoelectric cells starting from the a-th photoelectric cell as illustrated in Fig. For example, when the photovoltaic cell at the point at which the light intensity distribution curve indicates the maximum slope is the center cell (X _m ), the range of the photoelectric cell is set such that the number of the preceding and succeeding photoelectric cells from the center cell (X _m ) . That is, the position of the center cell X _m is defined as m, and when n is set to an odd number, the starting position of the photoelectric cell can be set to a = m - (n-1) / 2. Here, a has a positive value.

The advantage of using a part of the total photoelectric cells in calculation of refractive index characteristic points is that the amount of computation can be reduced. In addition, in the region before the increase of the quantity of light is started, most of the influence by the external light is not significant and the error of the noise due to the offset of the photoelectric cell is included However, limiting the calculation range of the photoelectric cell has the advantage that this influence can be ruled out. Further, when the calculation range of the photoelectric cell is set using the center cell, there is an advantage that the range of the photoelectric cell having meaning in the calculation of the refractive index can be easily and effectively found.

As a method for finding the center cell (X _m ), the magnitude of the light quantity of each photoelectric cell along the array direction of the photoelectric cells is calculated with respect to the light quantity of the previous photoelectric cells, and the photoelectric cell, X _m ) can be used. According to this method, the center cell (X _m ) can be found by a simple method while reducing the amount of computation.

Up to now, a method of finding the refractive index characteristic point from the light intensity distribution curve has been described. The refractive index characteristic point can be calculated by this method, and the refractive index of the sample can be calculated using the calculated refractive index characteristic point. In order to calculate the refractive index of the sample from the refractive index characteristic point, the relationship between the refractive index and the refractive index characteristic point of the sample obtained through the experiment can be used. As described above, since the refractive index characteristic point calculated by the equation (1) or (2) reflects the refractive index characteristic of the sample, the refractive index of the sample obtained through the experiment and the refractive index characteristic point relational data obtained by the equation The refraction index of the sample can be obtained by applying the refractive index characteristic point calculated by the equation The relationship between refractive index and refractive index characteristic point data obtained from the experiment can be used in approximate form or stored in a table form. As a method of calculating the refractive index using the refractive index characteristic point, although it is possible to directly use the data of the relationship between the refractive index characteristic point and the refractive index, the parameter is generated through an operation process such as temperature compensation for the refractive index characteristic point, You can also use the parameters to calculate the refractive index.

Next, the refractive index calculation method according to the embodiment of the present invention will be described with reference to FIG.

First, the position of the center cell having the largest slope can be found based on the light amount distribution according to the position of the photoelectric cells arranged in one direction (step S610). For this purpose, it is possible to use a method of calculating the magnitude of the light quantity of each photoelectric cell relative to the light quantity of the immediately preceding photoelectric cell along the array direction of the photoelectric cells, and designating the photoelectric cell having the largest light quantity as the center cell. It is possible to find the center cell by a simple method while reducing the amount of computation.

Next, the range of photoelectric cells for calculating the refractive index characteristic point around the center cell can be set (S620). The range of the photoelectric cell can be set to include n photoelectric cells starting from the a-th photoelectric cell. For example, when a photoelectric cell at a point at which the light intensity distribution curve indicates the maximum slope is used as a center cell, the same number of photoelectric cells before and after the center cell can be included. That is, when the position of the center cell is defined as m and the number of the photoelectric cells to be calculated is set to n (odd number), the starting position of the photoelectric cell can be set to a = m - (n-1) / 2. Where a has a positive value.

The refractive index characteristic point can be calculated from the light amount distribution in the range of the photoelectric cell set next (S630). The calculation method of the refractive index characteristic point is as described in detail in Equations (1) and (2) above, and redundant description is omitted here.

The refractive index of the sample can be calculated from the calculated index of refraction characteristic point (S640). As the method of calculating the refractive index of the sample from the refractive index characteristic point, the data obtained through the experiment can be used as described above, and the parameter generated through the calculation processing on the refractive index characteristic point can be used.

7 is a view illustrating a method of calculating a refractive index according to another embodiment of the present invention. The refractive index calculation method according to the embodiment of FIG. 7 may be performed in the refractive index measurement apparatus illustrated in FIG. 1, as in the embodiment of FIG. A refractive index calculation method according to another embodiment of the present invention will be described with reference to FIG.

First, the position of the center cell having the largest slope can be calculated based on the light amount distribution according to the position of the photoelectric cells arranged in one direction (step S710). For this purpose, it is possible to use a method of calculating the magnitude of the light quantity of each photoelectric cell relative to the light quantity of the immediately preceding photoelectric cell along the array direction of the photoelectric cells, and designating the photoelectric cell having the largest light quantity as the center cell. It is possible to find the center cell by a simple method while reducing the amount of computation. However, the method of finding the center cell is not limited to such a method.

Next, the number of times of calculation of the temporary characteristic point is set (S720), the temporary characteristic point is calculated by the set number of times while changing the range of the target cell for calculating the temporary characteristic point (S730) The refractive index characteristic point can be calculated on the basis of S740.

In the embodiment described with reference to FIG. 6, the value calculated using Equation 1 is used as the refractive index characteristic point, but in the embodiment illustrated in FIG. 7, the value calculated using Equation 1 is used as the refractive index characteristic point However, since the temporary characteristic points are calculated at least two times while changing the range of the photoelectric cells to be calculated, the refractive index characteristic points are calculated using the calculated temporary characteristic points. .

The temporary characteristic point Z _c can be calculated using the following equation (3).

(3)

Here, a is the start position of the photoelectric cell used for calculating the temporary characteristic point, n is the number of photoelectric cells to be used for calculation of the temporary characteristic point, X _i is the position value of the i th photoelectric cell, Y _i is the light amount .

Y _i can be the amount of light measured in the photoelectric cell, but it is also possible to use a result obtained by filtering or calculating the light amount measured in the photoelectric cell. As an example of the arithmetic processing, the average value of the adjacent cell (s) can be used. For example, the light amount of any photoelectric cell may be the average value of the previous cell (s) and the subsequent cell (s). In this case, there is an advantage that the influence of noise and the like can be reduced. The number of cells used to calculate the average using adjacent cells may be set to three, five, and so on.

Equation (3) is similar to Equation (1), but differs in that the result is defined as a temporary characteristic point (Z _c ) rather than a refractive index characteristic point (X _c ). That is, the temporary characteristic point Z _c is similar to the characteristic point calculated by using the amount of transmitted light as described in Equation (1), but it is an intermediate step for calculating the refractive index characteristic point without using it as a refractive index characteristic point As a result,

Z _c (a, n) in the formula (3) is a function of the starting position (a) of the photoelectric cell used for calculation of the temporary characteristic point (Z _c ) Means that the point (Z _c ) is expressed.

The following equation (4) can be used to calculate the refractive index characteristic point X _c from the temporary characteristic point Z _c .

(4)

Here, Z _c is the temporary characteristic point, m is the center cell number, (mj) is the starting position of the calculation of the temporary characteristic point Z _c (corresponding to a in Equation 3), (2j + Z _c) the number of cells used in the calculation (corresponding to n of equation 3), d is a transient characteristic point (Z _c) calculating the number, b is a first temporary attribute in the calculation repeatedly a temporary characteristic point (Z _c) Is a value for designating the start position (mb) of the cell used when calculating the point (Z _c ), and X _m is the center cell position value. b, and d are positive integers.

Fig. 8 is a view for explaining a calculation flow of a refractive index characteristic point ( _Xc ) according to the embodiment of Fig. The meaning of Equation (4) will be described in detail with reference to FIG.

First, the position of the center cell X _m can be calculated (S810). The center cell (X _m ) calculates the magnitude of the light quantity of each photoelectric cell relative to the light quantity of the immediately preceding photoelectric cell along the array direction of the photoelectric cells, and calculates the photoelectric cell having the largest light quantity as the center cell (X _m ) Can be set. When the position of the center cell X _m is calculated, the number m of the center cell can also be specified.

Next, j = b is set as an initial value for the iterative calculation of the temporary characteristic point (Z _c ) 820). Then, the start position a = mj of the photoelectric cells for calculation of the temporary characteristic point Z _c is set, and the number n of photoelectric cells is set to 2j + 1 (S830). The temporary characteristic point Z _c may be calculated using the starting position a of the photoelectric cell and the number n of the photoelectric cells which define the range of the target photoelectric cell in operation S840. Equation (3) can be used for the calculation of the temporary characteristic point (Z _c ).

Next, it is confirmed whether j is smaller than b + d (S850). If j is smaller than b + d, the value of j is incremented by one (S860), and steps S830 and S840 are repeated. J is equal to b + d from the S850 step, or greater, because the d calculate one for the temporary characteristic point (Z _c) has completed the temporary characteristic point (Z _c) the end the calculating step, and calculates d times the temporary characteristic point (Z _c ) to calculate the refractive index characteristic point (X _c) using (S870).

The procedure of Fig. 8 will be described with a specific example. When b = 1, j = b = 1 in the first calculation of the temporary characteristic point (Z _c ), so that the starting position (a) of the calculation target photoelectric cell range is one cell before the center cell (X _m ) a = mj = m-1), and the number of target photoelectric cells included in the calculation is three (n = 2j + 1 = 2 + 1). That is, the first temporary characteristic point Z _c is calculated using three cells including one previous cell and one subsequent cell based on the center cell X _m . In the second calculation, the value of j is increased by 1 and j = 2, so that the starting position of the range of photoelectric cells to be calculated becomes the two previous cells (a = mj = m-2) of the center cell, (N = 2j + 1). That is, a second temporary characteristic point Z _c is calculated using five cells including two previous cells and two subsequent cells based on the center cell X _m . In this manner, j = b + d , The d temporary characteristic points Z _c can be calculated by repeating d times while expanding the range of the target photoelectric cell.

In summary, in Equation _{4 Z c (mj, 2j +} 1) it is every single temporary characteristic point (Z _c) a and the start position of the calculated target photoelectric cell range to calculate the mj value 2j the number of the calculation target photoelectric cell +1, and the meaning of the sigma means that the temporary characteristic point Z _c is calculated d times while changing the range of the photoelectric cell to be calculated.

Thus the refractive index characteristic point (X _c) is a temporary characteristic point (Z _c) to but calculated using the temporary characteristic point (Z _c) a temporary characteristic point (Z _c) while changing the range of the target cell for calculating at least Can be calculated based on the results calculated more than once. The range of the target cell for calculating the temporary characteristic point Z _c can be set around the center cell X _m and the range of the target photoelectric cell can be changed by changing the range of the center cell X _m And the number of the target photoelectric cells is increased while maintaining the same.

Referring again to Figure 7, one can calculate the refractive index with a refractive index characteristic point (X _c) (S750). Refractive index characteristics of the refractive index that the refractive index and to calculate the index of refraction of the sample from (X _c) The samples obtained from the experiments characteristic point (X _c) may be the relationship data. Since the refractive index characteristic point (X _c) calculated by the equations (3) and (4) as described above is reflected in the refractive index characteristic of the sample, the refractive index and the refractive characteristics of the samples obtained from the experimental point (X _c) Relationship data The refractive index characteristic point (X _c ) of the sample can be known. The relationship between the refractive index and the refractive index characteristic point (X _c ) of the sample obtained through the experiment can be used in approximate form or stored in a table form. A method using a refractive index characteristic point (X _c) for calculating the refractive index, the refractive index characteristic point (X _c) and may be a direct relationship data of the refractive index. However, operations such as temperature compensation for the refractive index characteristic point (X _c) It is also possible to calculate the refractive index by generating parameters through processing and acquiring the relationship data between the generated parameters and the refractive index through experiments.

7, it is illustrated that the step of calculating the position of the center cell (S710) is performed earlier than the step (S720) of setting the number of times of calculation of the temporary characteristic point (Z _c ). However, ≪ / RTI >

7, since the amount of transmitted light is calculated based on the amount of light detected by the photoelectric sensor and the refractive index characteristic point X _c is calculated based on the calculated amount of transmitted light, accurate refractive index detection is possible by reducing the influence of external light There are advantages. In the embodiment shown in FIG. 7, the simple average of the results obtained by calculating the temporary characteristic point Z _c several times as shown in the formula (4) is not used as the refractive index characteristic point X _c , (2 · Z _c -X _m = Z _c + (Z _c -X _m )) obtained by adding the difference between the temporary characteristic point Z _c and the center cell X _m to the temporary characteristic point Z _c and using a refractive index characteristic point (X _c), according to this method has the advantage that a change in the refractive index characteristic point (X _c) due to the refractive index of the sample is amplified to increase the resolution of refractive index detection.

Further, according to the center cell (X _m) temporary characteristic point (Z _c) while changing the range of the subject photoelectric cells mainly in the way of calculating multiple times, the center cell (X _m) detects a value of the photoelectric cell in the vicinity of Is more influential than the detection value of the photoelectric cell located far from the center cell (X _m ). For example, the number of photovoltaic cells immediately adjacent to the central cell may be reduced in the number of photoelectronic cells that are included in the calculation but are far from the central cell. That is, there is an effect of giving a weight according to the position of the photoelectric cell.

As described above, the present invention uses a method of calculating the refractive index by calculating the light amount of the transmitted light, rather than finding the total reflection point from the light amount distribution detected by the photoelectric sensor. According to the present invention, it is possible not only to eliminate the necessity of accurately finding the total reflection point in the light amount distribution of the reflected light, but also to solve the problem of the amount of light emitted from the light source and the influence of external light, and to improve the accuracy of the refractive index measurement.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: refractive index measuring device
110: Light source
120: prism
130: Photoelectric sensor
131: photoelectric cell
140:
150:
S: Sample

Claims (12)

A light source for irradiating light to an interface between the sample and the prism;
A photoelectric sensor in which a plurality of photoelectric cells receiving light reflected at the interface and generating an electric signal corresponding to a light amount of the received light are arranged along one direction; And
And calculation means for calculating a refractive index characteristic point by using a distribution of light quantity according to the position of the photoelectric cell in the array direction of the photoelectric cells and calculating a refractive index of the sample based on the calculated refractive index characteristic point,
Calculating a refractive index characteristic point based on a result of calculating the temporary characteristic point at least twice or more while calculating a range of a target cell for calculating the temporary characteristic point using the temporary characteristic point; In addition,
Wherein the range of the target cell for calculating the temporary characteristic point is set around a center cell and the range of the target cell is changed by changing the number of target cells while maintaining the same center cell Refractive index measuring device. The refractive index measurement apparatus according to claim 1, wherein the refractive index characteristic point is calculated based on an amount of transmitted light. delete delete [3] The method of claim 1, wherein the center cell calculates a magnitude of light quantity of each of the photoelectric cells along the arrangement direction of the photoelectric cells with respect to the quantity of light of the previous photoelectric cell, And the refractive index of the diffraction grating. 2. The refractive index measurement apparatus according to claim 1, wherein the temporary characteristic point is calculated using the following equation.
(Equation)

Here, a is the start position of the photoelectric cell used for calculating the temporary characteristic point, n is the number of photoelectric cells to be used for calculation of the temporary characteristic point, X _i is the position value of the i th photoelectric cell, Y _i is the light amount . 2. The refractive index measurement apparatus according to claim 1, wherein the refractive index characteristic point is calculated using the following equation using the temporary characteristic point.
(Equation)

Here, Z _c is a transient characteristic point, m is the main cell number, (mj) is the starting position of the photoelectric cell is used in a temporary characteristic point calculation, (2j + 1) is the number of the photoelectric cells is used to calculate the temporary characteristic point, d B is a variable designating the starting position (mb) of the photoelectric cell used when calculating the first temporary characteristic point, and X _m is the center cell position value. A refractive index measurement method performed by a refractive index measurement apparatus including a photoelectric sensor in which a plurality of photoelectric cells are arranged in one direction,
Calculating a refractive index characteristic point based on a light amount distribution according to a position of a photoelectric cell arranged along the one direction; And
And calculating a refractive index of the sample from the calculated refractive index characteristic point,
Wherein the step of calculating the refractive index characteristic point comprises:
Calculating a temporary characteristic point by a predetermined number of times using a transmitted light quantity while changing a range of a target photoelectric cell; And
And calculating the refractive index characteristic point based on the calculated temporary characteristic points,
Wherein the range of the target photoelectric cell is set with the center cell as a center and the range of the target photoelectric cell is changed by changing the number of target photoelectric cells while maintaining the same center cell . The method according to claim 8, wherein the step of calculating the refractive index characteristic point comprises the steps of: calculating an amount of transmitted light based on the amount of light detected by the photoelectric sensor; and calculating the refractive index characteristic point based on the calculated amount of transmitted light. How to measure. delete delete The method of claim 8, wherein the center cell calculates a magnitude in which the light quantity of each photoelectric cell increases along the array direction of the photoelectric cells with respect to the light quantity of the immediately preceding photoelectric cell, And the refractive index of the refractive index of the refractive index layer.

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