Linearity correction method for optical measurement device, optical measurement method, and optical measurement device

Abstract

The present invention provides a linear correction method for an optical measuring device, an optical measuring method, and an optical measuring device, which can perform linear correction of an optical measuring device using a CMOS linear image sensor with high precision. The linear correction method for an optical measuring device having a CMOS linear image sensor comprises: an exposure step, in which a reference light with a constant intensity is sequentially incident on a photosensitive element of interest of the CMOS linear image sensor by changing the exposure time; a measurement value acquisition step, in which the measurement values ​​of the photosensitive element of interest are sequentially acquired; an actual linear error calculation step, in which an actual linear error representing a difference between a linear value obtained based on the exposure time corresponding to the measurement value and the measurement value is sequentially calculated; and a fitting step, in which a first function representing a first linear error is fitted to each of the actual linear errors.

Description

Technical Field

[0001] The present invention relates to a linearity correction method for an optical measuring device, an optical measuring method and an optical measuring device. Background Art

[0002] Sometimes, CCD (Charged-coupled devices) linear image sensors are used in optical measurement devices such as multi-channel spectrometers. Specific wavelength portions of the measurement light separated by the diffraction grating are incident on the light receiving elements arranged in the CCD linear image sensor, and these light receiving elements output electrical signals corresponding to the light intensity. However, although general CCD linear image sensors have the advantage of high sensitivity, they tend to be complex in structure and expensive.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-15628 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As an electronic component having the same function as the CCD linear image sensor, a CMOS (Complementary Metal Oxide Semiconductor) linear image sensor is also known. The CMOS linear image sensor has the advantages of being relatively simple in structure, inexpensive, low in power consumption, and easy to increase in speed.

[0008] However, compared with CCD linear image sensors, CMOS linear image sensors have the disadvantage of poor linearity. That is, there is a disadvantage that even if light with an intensity of α times is incident on each light receiving element arranged in the CMOS linear image sensor, a measurement value of α times may not be obtained. Therefore, there is a problem that the intensity of the measurement light cannot be immediately determined based on the original output value of the CMOS linear image sensor. Therefore, when using a CMOS linear image sensor in an optical measurement device, high-precision linear correction is required.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a linear correction method capable of accurately performing linear correction of an optical measurement device using a CMOS linear image sensor, an optical measurement method using the method, and an optical measurement device.

[0010] Solutions for solving problems

[0011] In order to solve the above-mentioned problem, the linear correction method of the present invention is a linear correction method of an optical measurement device equipped with a CMOS linear image sensor, characterized in that the linear correction method includes: an exposure step, in which the exposure time is changed so that the reference light with constant intensity is sequentially incident on the attention light receiving element of the CMOS linear image sensor; a measurement value acquisition step, in which the measurement values ​​of the attention light receiving element are sequentially acquired; an actual linear error calculation step, in which the actual linear error representing the difference between the linear value obtained based on the exposure time corresponding to the measurement value and the measurement value is sequentially calculated; and a fitting step, in which a first function representing a first linear error is fitted to each of the actual linear errors.

[0012] Here, the first function may be a quadratic function.

[0013] In addition, the fitting step may determine the variable parameter of the first function by a least square method using an objective function representing the total amount of the difference between the actual linear errors and the first linear error. The objective function may include a term representing the difference between the first linear error and the actual linear error corresponding to each of the measured values. These terms may be weighted by a deviation amount representing the deviation of each of the measured values.

[0014] Furthermore, the method may further include an exposure time correction step of performing exposure time correction on the measurement value corrected by the first function.

[0015] Furthermore, the exposure time correction step may perform the exposure time correction by applying a second function that is closer to a predetermined value as the exposure time is longer to the measurement value corrected by the first function.

[0016] Here, the second function may also be a fractional function.

[0017] Furthermore, the measurement value may be acquired based on a difference between a first output value of the attention light receiving element when the reference light is incident and a second output value of the attention light receiving element when the reference light is not incident.

[0018] Furthermore, the fitting step may execute the fitting using the measurement value acquired based on the first output value being equal to or greater than a predetermined threshold value.

[0019] In addition, the CMOS linear image sensor may include a non-noticeable light receiving element that is not incident on the noticeable light receiving element during the time when the reference light is incident on the noticeable light receiving element. In this case, the linear correction method may further include a basic correction value calculation step of calculating a basic correction value that makes the measurement value of the non-noticeable light receiving element close to zero during the time when the reference light is incident on the noticeable light receiving element. The measurement value acquisition step may sequentially acquire the measurement values ​​corrected by the basic correction value.

[0020] The optical measurement method of the present invention is an optical measurement method using any one of the above-mentioned linear correction methods, and when the measurement light enters the attention light receiving element, the measurement value of the attention light receiving element is corrected based on the first function.

[0021] There may be a plurality of the attention light receiving elements. Furthermore, when the measurement light enters each of the attention light receiving elements, the measurement value of the attention light receiving element may be corrected based on a function representing the first function obtained for each of the plurality of attention light receiving elements.

[0022] The optical measurement device of the present invention includes: a storage unit that stores correction parameters corresponding to the first function obtained by any one of the above-mentioned linear correction methods; and a correction unit that uses the correction parameters to correct the measurement value of the attention light receiving element when the measurement light is incident on the attention light receiving element. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an overall configuration diagram of an optical measurement device according to one embodiment of the present invention.

[0024] Figure 2 is a schematic diagram of a CMOS linear image sensor.

[0025] Figure 3 : is a flowchart showing a method of calculating correction parameters.

[0026] Figure 4 : is a flowchart showing a method of calculating correction parameters.

[0027] Figure 5 It indicates the measured value S i Spectrum diagram of .

[0028] Figure 6 yes Figure 5 A partial enlarged view of .

[0029] Figure 7 The first corrected measurement value S' is calculated by increasing the exposure time t. i A graph showing the change in with the ideal straight line Li.

[0030] Figure 8 is the first corrected measurement value S' i The actual linear error e' i Graph of the relationship.

[0031] Fig. 9 It represents the function f(S' i ) to the actual linear error e' i The fitted graph of .

[0032] Fig.10 is the second corrected measurement value S using the function f" i The actual linear error is e” i Graph of the relationship.

[0033] Fig.11 is the actual linear error e" that represents the increase in exposure time t i Graph of changes.

[0034] Fig.12 is the third corrected measurement value S' i The actual linear error is e' i Graph of the relationship.

[0035] Fig.13 is a flowchart showing an optical measurement method using calibration parameters.

[0036] Description of reference numerals:

[0037] 10: Optical measuring device,

[0038] 11: Light source (sample),

[0039] 12: Slit,

[0040] 13: Cut-off filter,

[0041] 14: Collimator lens,

[0042] 15: Diffraction grating,

[0043] 16: Focusing lens,

[0044] 17: CMOS linear image sensor,

[0045] 17-i (i=0~1023): light-receiving element,

[0046] 18: Operation unit. DETAILED DESCRIPTION

[0047] Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

[0048] Figure 1 1 is a diagram showing the structure of an optical measurement device according to an embodiment of the present invention. The optical measurement device 10 is a device that measures the light intensity of each wavelength, that is, the optical spectrum, by splitting the light emitted from the sample such as the light source 11. The optical spectrum can be directly used as optical characteristic information of the light source 11, for example. In addition, when the sample is a thin film, the optical spectrum of the reflected light of the thin film can be used to calculate the thickness of the thin film, for example.

[0049] The light emitted from the sample such as the light source 11 is irradiated to the slit 12 provided in the optical measurement device 10. The slit 12 has, for example, a long and narrow rectangular opening. A cut filter 13 is arranged on the back side of the slit 12 as required. The cut filter 13 blocks the light of wavelength outside the measurement range. The measurement light passing through the cut filter 13 reaches the collimator 14. The collimator 14 is, for example, a concave mirror with a constant curvature, and reflects the measurement light passing through the slit 12 and converts it into parallel light, and irradiates the parallel light to the diffraction grating 15.

[0050] The diffraction grating 15 diffracts each wavelength component of the light irradiated from the collimator 14 in a direction corresponding to the wavelength. The diffraction grating 15 is, for example, a reflective diffraction grating, and a plurality of grooves extending in the same direction as the opening of the slit 12 may be provided on the reflection surface. Thus, the diffraction grating 15 reflects each wavelength component of the light irradiated from the collimator 14 so that the intensity thereof becomes greater in the direction corresponding to the wavelength.

[0051] The focusing mirror 16 is, for example, a concave mirror with a constant curvature, and reflects the light of each wavelength component diffracted by the diffraction grating 15 and focuses it on each light receiving element arranged on the CCD linear image sensor 17. Figure 2 As shown schematically, it includes a plurality of (here, 1024) light receiving elements 17-0 to 17-1023 arranged at equal intervals in the diffraction direction of the diffraction grating 15. Each light receiving element 17-i includes a photodiode that accumulates charges that increase in accordance with the intensity and time of the received light, and outputs a value corresponding to the amount of accumulated charge. Each light receiving element 17-i is assigned a wavelength corresponding to its arrangement order, and outputs the intensity of the light component of the assigned wavelength. Here, the subscript i represents a wavelength channel (0 to 1023).

[0052] The output value of each light receiving element 17 - i is input to the calculation unit 18 mainly composed of a computer. In the calculation unit 18 , various corrections such as linear correction are performed on each output value to obtain a measured value of the light intensity of each wavelength component.

[0053] The CMOS linear image sensor 17 has the disadvantage of linear degradation as described above. Therefore, in the optical measurement device 10, various corrections are applied to the raw output values ​​of each light receiving element 17-i of the CMOS linear image sensor 17 to achieve linearity. That is, the transformation based on the correction parameters is applied to the raw output values ​​of each light receiving element 17-i and used as the measurement value. The measurement value obtained in this way has the so-called linearity that when the intensity of light increases to α times, it also increases by α times.

[0054] Figure 3 and Figure 4is a flowchart showing a method for calculating linear correction parameters. Here, the correction of the measured value based on the CMOS linear image sensor 17 includes the following three corrections: 1) a first correction to make the measured value in the short wavelength region not less than zero; 2) a second correction to achieve linearity in the region with high light intensity; and 3) a third correction to achieve linearity in the region with low light intensity. These three corrections are applied sequentially to the original output value of each light receiving element 17-i. It should be noted that Figure 3 and Figure 4 The processing shown is executed by a computer such as the calculation unit 18 .

[0055] In order to obtain the correction parameters for the first correction, the second correction, and the third correction, first, in the optical measurement device 10, the raw output value A of each light receiving element 17-i of the CMOS linear image sensor 17 is obtained without allowing light to enter the device through the slit 12. i o(S101).

[0056] Next, a reference light having a constant light intensity, such as white light from a halogen lamp, is made to enter the device from the slit 12, and the exposure time t is increased from 0 to t max , and simultaneously obtain the original output value A of each light receiving element 17 - i of the CMOS linear image sensor 17 i (S102). During the exposure time t from 1 to t max When ts changes successively, the output value A of each wavelength channel i i Included max / ts values ​​(here, t max =10000).

[0057] Next, calculate the output value A i Subtract output value A i The value obtained by i (S103). During the exposure time t from 1 to t max When ts is changed successively, the measured value S of each wavelength channel i is i Included max / ts values.

[0058] Figure 5 It indicates the measured value S i The horizontal axis corresponds to the wavelength channel i, and the vertical axis corresponds to the measured value S i Here, four spectra corresponding to exposure times t=100, 3000, 6000, and 10000 are shown. Figure 5 The measured value S is shown near the wavelength channel i=200. i It increases from near zero and decreases to near zero near the wavelength channel i=600. Figure 6 It means that Figure 5 The enlarged part of wavelength channel i = 0 to 150 in FIG. Figure 6 As shown, in the region where the wavelength channel i is small (i.e., short wavelength), the measured value S i Sometimes it is a value less than zero. Therefore, here, for each exposure time t, the measured value S i The measured value S is calculated for a predetermined number of wavelength channels i (here, i=0 to 9) which are originally considered to be zero. i The average value of is set as b (S104). That is, when the exposure time t is from 1 to t max When ts is changed successively, the correction parameter b (basic correction value) includes t max For each combination of exposure time t and wavelength channel i, from the measured value S i Subtract the correction parameter b, and the first corrected measurement value S' is obtained. i (S105) It should be noted that, as described later, in order to obtain the first corrected measurement value S' i In order to reduce the statistical deviation, the processes from S102 to S105 are repeated multiple times (for example, 100 times) under the same conditions.

[0059] Next, the measured value S' i Transformed into actual linear error e' i . Figure 7 The first corrected measurement value S' is calculated by increasing the exposure time t. i The change of is compared with the ideal straight line Li. Figure 7 The horizontal axis represents the exposure time t and the horizontal axis represents the first corrected measurement value S'. i The ideal straight line Li is the maximum exposure time t = t max and the first corrected measurement value S' at this time i The value (this value is denoted as S' imax . ) constitutes the point (t max , S' imax ) and the straight line connecting the origin (0, 0) (S106). Actual linear error e' i The following formula (1) shows the ideal straight line Li and the first corrected measurement value S' i The difference accounts for the first corrected measurement value S' i ratio (S107).

[0060] Equation 1

[0061]

[0062] Figure 8 is the first corrected output value S' i The actual linear error e'i Here, the case where i=456 is shown as an example. Figure 8 As shown, with the first corrected output value S' i becomes larger, the actual linear error e' i In addition, in the first corrected measurement value S' i In the small area, the actual linear error e' i The first corrected measurement value S' i In the large area, the actual linear error e' i Therefore, in the second calibration, the first calibrated measurement value S' i The improvement of the linearity of the measurement value of the CMOS linear image sensor 17 is sought with the large area, that is, the area with a large exposure time t as the center.

[0063] Therefore, firstly calculate the actual linear error e' by the following formula (2): i The error Δe' i (S108). Formula (2) is derived based on the well-known law of error propagation. Error Δe' i For each exposure time t and the first corrected measurement value S' i In formula (2), ΔS' i and ΔS' imax Represents the first corrected measurement value S' i and S' imax The sample standard deviation of Figure 8 As shown, the error Δe' i At exposure time t, the first corrected measurement value S' i It increases when the value is small, and decreases when the value is large. It should be noted that the error Δe' i It represents the measured value S' i The deviation amount can also be calculated by other calculation formulas.

[0064] Equation 2

[0065]

[0066] Next, a quadratic function f(S') representing the linear error is prepared for each wavelength channel i. i )=C2×S' i 2 +C1×S' i +C0, in each wavelength channel i, make f(S' i ) and the actual linear error e' iFitting (S109). The least square method is used in the fitting. Thus, the coefficients C0, C1, and C2 are determined. Here, as an example of the first function of the present invention, a quadratic function is used, but other functions may be used.

[0067] It should be noted that the fitting in S109 may also be performed only for the exposure time t=t max Output value A i This is performed for wavelength channels i that are equal to or larger than a predetermined threshold. In this case, the coefficients C0, C1, and C2 are determined only for such wavelength channels i.

[0068] Fig. 9 is the quadratic function f(S' i ) to the actual linear error e' i Here, the case of i=456 is also shown as an example. The horizontal axis represents the measured value S' i , the vertical axis represents the actual linear error e' i The black dots in the figure represent the measured values ​​S' i and the actual linear error e' i The measurement point (S' i , e' i ). The right-falling curve represents the shape of the quadratic function f fitted to these measurement points. In addition, the vertical line segment passing through each black dot represents the error Δe' i .like Fig. 9 As shown, in the measured value S' i The error Δe' in the small area (i.e. the area with short exposure time t) i becomes relatively large. And, in this case, the error Δe' i In the large area, the degree of fitting the quadratic function f to the measured point is reduced, and vice versa in the error Δe' i In a small area, the degree of fitting of the quadratic function f to the measured point is improved. Therefore, the objective function in the least squares method is the quadratic function f(S' i ) and the actual linear error e' i The weighted sum of the differences is calculated using the error Δe' i The reciprocal of is used as the weight. Thus, at the exposure time t, the first corrected measurement value S' i In the region with large values, the quadratic function f(S' i ) is determined by the actual linear error e' i Perform the fitting.

[0069] Next, using the coefficients C0, C1, and C2 determined in S109, the second corrected measurement value S" is calculated by the following equation (3): i (S110).

[0070] Equation 3

[0071]

[0072] It should be noted that in S109, the coefficients C0, C1, and C2 are determined for each wavelength channel i. Therefore, when calculating the second corrected measurement value S" i In the case of , the coefficients C0, C1 and C2 determined for the same wavelength channel i are used.

[0073] It should be noted that, for the sake of convenience, the average values ​​(representative values) of C0, C1, and C2 are calculated in advance. In formula (3), these representative values ​​(i.e., one quadratic function representing a plurality of quadratic functions prepared for each wavelength channel) may be shared among all wavelength channels i. In particular, when only the exposure time t=t max The first corrected measurement value S' i When fitting in S109 is performed for wavelength channels having values ​​greater than or equal to a predetermined threshold, the second corrected measurement value S" can be appropriately calculated by using the average value of C0, C1, and C2 for wavelength channels for which fitting in S109 is not performed. i .

[0074] Next, for each wavelength channel i, the second corrected measurement value S" i Transformed into actual linear error e" i (S111). Actual linear error e” i It can also be calculated by the same formula as the above formula (1).

[0075] Fig.10 is the second corrected measurement value S using the function f" i The actual linear error is e” i Here, the case where i=456 is also shown as an example. Fig.10 As shown, at the measured value S" i In the area above 0.2, the actual linear error e" i is a sufficiently small value, and linearity can be fully achieved in this region. However, at the measured value S" i In the area where the exposure time is short, the linearity is insufficient. Therefore, in this embodiment, the exposure time correction is implemented as the third correction. The exposure time correction is to adjust the measured value S in the area with short exposure time according to the length of the exposure time. i Specifically, the third corrected measurement value S"' is defined by the following formula (4): i That is, by the second corrected measurement value S" iMultiplying by the fractional function t / (t-d) as an example of the second function of the present invention, the third corrected measurement value S"' is obtained. i Here, d is the correction exposure time. The larger d is, the greater the correction amount is. However, in the area where the exposure time t is large, the correction amount becomes smaller, and the second corrected measurement value S" i and the third corrected measured value S' i It should be noted that the second function is not limited to the above-mentioned fractional function, and any function may be used as long as it approaches a specified value (here 1) as the exposure time t increases, increases as the exposure time approaches 0, and changes shape according to a variable parameter.

[0076] Equation 4

[0077]

[0078] Next, as shown in the following equation (5), assuming that the third corrected measurement value S'' i Proportional to the exposure time t.

[0079] Equation 5

[0080] S″′ i =at...(5)

[0081] By using equations (4) and (5), and the second corrected measurement value S" i The corresponding actual linear error is e" i , as shown in the following equation (6), as a function g(t) of exposure time t with correction parameter d.

[0082] Equation 6

[0083]

[0084] Next, using the result of S111, the function g(t) is correlated with the measurement point (t, e" i ) fitting (S112). The correction parameter d is determined thereby. Fig.11 : is a graph showing the fitting. Here, the case where i=456 is also shown as an example.

[0085] Then, using the determined parameter d, the second corrected measurement value S" is calculated by equation (4). i Transformed into the third corrected measurement value S' i (S113) It should be noted that in S112, the correction parameter d is determined for each wavelength channel i. Therefore, the third corrected measurement value S"' can be calculated by using the correction parameter d corresponding to the wavelength channel i for each wavelength channel i through the formula (4). iAlternatively, the average value of the correction parameter d may be calculated, and the average value may be shared among all wavelength channels i, and the third corrected measurement value S"' may be calculated by equation (4): i .

[0086] Fig.12 is the third corrected measurement value S' i The actual linear error e"' calculated from this i Here, the case where i=456 is also shown as an example. Fig.12 As shown, it can be seen that through the first to third corrections, in S"' i The linear error e"' in the whole area i Converges to a sufficiently small value, achieving full linearity in the entire region.

[0087] Finally, the A of each wavelength channel i obtained in S101 is i o, the correction parameters C0, C1, and C2 acquired in S109, and the correction parameter d acquired in S112 are stored in a memory or the like (S114). These correction parameters are used in optical measurement of the sample.

[0088] Fig.13 First, the light emitted from the sample such as the light source 11 is irradiated to the slit 12, and the output value A of the CMOS linear image sensor 17 is obtained by the calculation unit 18. i (i=0 to 1023) (S201). At this time, the exposure time ta of the measurement light to the CMOS linear image sensor 17 is set. ta can be set to the above t max A value that is large enough.

[0089] Next, the calculation unit 18 calculates the value of A obtained in S201. i Subtract the correction parameter A i o, get the measured value S i (i=0 to 1023) (S202). Then, for wavelength channels i=0 to 9, the measured value S is calculated. i Then, by taking the average value of the measured value S i Subtract the correction parameter b to obtain the first corrected measurement value S' i (S204).

[0090] The calculation unit 18 also calculates the first corrected measurement value S' i Apply the above formula (3) to obtain the second corrected measurement value S" i(i=0 to 1023) (S205) At this time, if the correction parameters C0, C1, and C2 are stored for each wavelength channel i, the correction parameters corresponding to the same wavelength channel i are used. If a common value (average value) is stored in all wavelength channels, this value is used.

[0091] The calculation unit 18 uses the exposure time ta and the correction parameter d to calculate the second corrected measurement value S" according to the above formula (4). i Calculate the third corrected measurement value S' i (S206) Here, if the correction parameter d is stored for each wavelength channel i, the correction parameter corresponding to the same wavelength channel i is used. If a common value (average value) is stored in all wavelength channels, this value is used.

[0092] Then, the calculation unit 18 outputs the third corrected measurement value S' calculated in S206 by display, printing, communication, etc. i (S207) It should be noted that, when the sample is a thin film, the calculation unit 18 may use the third corrected measurement value S' calculated in S206. i The film thickness can be calculated using a known algorithm.

[0093] According to the linearity correction method of the optical measuring device 10 described above, the output value S of the CMOS linear image sensor 17 is i By implementing the first to third calibrations, a measurement value S"' having sufficient linearity can be obtained. i , a high-precision optical spectrum can be obtained. In addition, the film thickness of the sample can be calculated with high precision using the optical spectrum.

[0094] It should be noted that the present invention is not limited to the above-mentioned embodiment, and various modifications are possible, and such modifications are naturally included in the scope of the present invention.

Claims

1. A linearity correction method for an optical measurement device having a CMOS linear image sensor, characterized in that: The linear correction method comprises: An exposure step of changing the exposure time so that reference light with a constant intensity is incident on the attention light receiving element of the CMOS linear image sensor in sequence; a measurement value acquisition step of sequentially acquiring the measurement values ​​of the light receiving element of interest; an actual linear error calculation step of sequentially calculating an actual linear error representing a difference between a linear value obtained based on the exposure time corresponding to the measured value and the measured value; and a fitting step of performing fitting of a first function representing a first linear error on each of the actual linear errors, The fitting step determines a variable parameter of the first function by a least square method using an objective function representing a total amount of differences between the actual linear errors and the first linear error, The objective function includes terms representing the difference between the first linear error and the actual linear error corresponding to each of the measurement values, and these terms are weighted by a deviation amount representing a deviation of each of the measurement values.

2. The linear correction method according to claim 1, wherein: The first function in the linear correction method is a quadratic function, and the linear correction method is a linear correction method for a CMOS linear image sensor.

3. The linear correction method according to claim 1, characterized in that: The method further includes an exposure time correction step of performing exposure time correction on the measured value corrected by the first function.

4. The linear correction method according to claim 3, characterized in that: The exposure time correction step performs the exposure time correction by applying a second function that is closer to a predetermined value as the exposure time is longer to the measured value corrected by the first function.

5. The linear correction method according to claim 4, characterized in that: The second function is a fractional function.

6. The linear correction method according to any one of claims 1 to 5, characterized in that: The measurement value is acquired based on a difference between a first output value of the attention light receiving element when the reference light is incident and a second output value of the attention light receiving element when the reference light is not incident.

7. The linear correction method according to claim 6, characterized in that: The linear correction method is a linear correction method for a CMOS linear image sensor. The fitting step performs the fitting using the measurement value acquired based on the first output value that is equal to or greater than a predetermined threshold value.

8. The linear correction method according to any one of claims 1 to 5 and 7, characterized in that: The CMOS linear image sensor includes a non-attention light receiving element in which light is not incident during a time when the reference light is incident on the attention light receiving element. The linear correction method also includes: a basic correction value calculation step of calculating a basic correction value that makes the measurement value of the non-noticeable light receiving element approach zero during the time when the reference light is incident on the noticeable light receiving element, The measurement value acquisition step sequentially acquires the measurement values ​​corrected by the basic correction values.

9. An optical measurement method using the linearity correction method according to any one of claims 1 to 8, wherein: When the measurement light enters the attention light receiving element, a measurement value of the attention light receiving element is corrected based on the first function.

10. The optical measurement method according to claim 9, wherein: There are a plurality of said attention light receiving elements, When the measurement light enters each of the light receiving elements of interest, the measurement value of the light receiving element of interest is corrected based on a function representing the first function obtained for each of the plurality of light receiving elements of interest.

11. An optical measuring device, characterized in that: include: a storage unit for storing correction parameters corresponding to the first function obtained by the linear correction method according to any one of claims 1 to 8; as well as The correction unit corrects a measurement value of the attention light receiving element using the correction parameter when the measurement light is incident on the attention light receiving element.

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