Optical property measurement device, wavelength shift correction device, wavelength shift correction method, and program

Abstract

In the present invention, the wavelength of incident light is measured on the basis of signals from a plurality of pixels of a photoelectric conversion element (5) lined up in the direction of dispersion of the incident light by a light-splitting means (4). When a wavelength shift is to be corrected, a wavelength shift measurement amount is calculated, the wavelength shift measurement amount being the difference between a measured value obtained by measuring the emission line wavelength of incident light from a wavelength shift correction light source (10) that radiates light including an emission line of at least one wavelength, from within the wavelength range in which dispersion by the light-splitting means (4) is possible, and the original emission line wavelength. An emission line wavelength shift reference amount is calculated using a polynomial in which the characteristics of the wavelength shift that occurs are represented by a polynomial of degree 1 or higher, with the wavelength or a parameter relating to the wavelength being used as a variable. The coefficients of the polynomial are determined from the calculated emission line wavelength shift measurement amount and emission line wavelength shift reference amount, and the wavelength of the incident light is corrected on the basis of the determined polynomial.

Description

[Technical Field]

[0001] This invention relates to an optical properties measuring device, a wavelength shift correction device, a wavelength shift correction method, and a program for measuring wavelength by spectrally analyzing incident light, such as a spectrophotometer or spectroluminometer. [Background technology]

[0002] In optical property measuring devices that spectrally analyze incident light to measure wavelength, the wavelength is generally calibrated at the factory before shipment, and measurements are taken using that calibrated wavelength until it is recalibrated. However, the actual measured wavelength can fluctuate due to changes in the position of optical components such as spectral means and lenses in the optical property measuring device over time, resulting in measurement errors. However, when the measured value of an object differs from what was expected, the user cannot determine whether the difference is due to a misalignment in the optical property measuring device or a difference in the object being measured. To find out, the measuring device had to be sent to the factory or service center for wavelength calibration. However, this meant that the user could not use the optical property measuring device while it was being calibrated.

[0003] To correct wavelength fluctuations, it is necessary to accurately know the amount of wavelength shift (wavelength variation) due to changes over time. Techniques for estimating the wavelength shift of a spectrometer are disclosed, for example, in Patent Document 1 and Patent Document 2. The techniques disclosed in Patent Documents 1 and 2 include a light source that emits emission lines at known emission line wavelengths, a spectrometer that disperses incident light according to wavelength and receives the dispersed light with multiple photoelectric conversion elements arranged in the dispersion direction, and a method for estimating the wavelength of emission line output from the relative output of the light receiving unit at the emission line wavelength when the spectrometer measures the emitted light from the light source for wavelength shift correction, and estimating the amount of wavelength change from the difference between the estimated wavelength of emission line output and the known emission line wavelength.

[0004] Mercury-cadmium lamps and neon lamps are known as light sources that emit emission lines, and Patent Document 1 discloses an example using a mercury-cadmium lamp. Mercury-cadmium lamps are often used for wavelength calibration of spectrometers, and because they have multiple emission lines in the visible light wavelength range, wavelength shifts can be estimated across the entire visible light wavelength range.

[0005] Patent Document 2 discloses a method for wavelength calibration of a spectrometer using the emission lines of a neon lamp. Neon lamps are small, inexpensive light sources often used as indicators in electrical products, and because they emit light with emission lines, it is possible to estimate the wavelength shift near the emission lines. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2017 / 018142 [Patent Document 2] International Publication No. 2019 / 039024 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, while the mercury-cadmium lamp used as a light source emitting emission lines in Patent Document 1 is useful for wavelength calibration of spectrometers in factories, it contains light of wavelengths that are dangerous if directly viewed in the ultraviolet region, there are no small lamp light sources available, and it contains harmful substances. Therefore, it is difficult to perform wavelength calibration easily without bringing it into factories, etc. For this reason, if a wavelength shift occurs, wavelength calibration at the factory or service center is still necessary.

[0008] On the other hand, the neon lamp used in Patent Document 2 does not have the problems of mercury-cadmium lamps and can be used as an inexpensive, compact, and safe light source for wavelength calibration. Therefore, if wavelength calibration can be easily performed using a neon lamp, users of optical property measuring devices can, for example, estimate the amount of wavelength deviation using an emission line light source when the measurement error becomes large, without having to send the measuring device back to the factory or service center, and can verify whether the error is due to a deviation in the optical property measuring device.

[0009] Although neon lamps have multiple emission lines, there are only a few relatively independent emission lines around 724 nm that can be used for wavelength estimation, and the wavelength shift can only be estimated in that wavelength range. In the method described in Patent Document 2, the wavelength shift estimated using the emission line wavelength around 724 nm of the neon lamp is applied to the entire visible light wavelength range to correct the wavelength shift.

[0010] However, depending on the optical design of the optical property measurement device, the wavelength shift caused by the temporal positional changes of optical components does not occur uniformly in the visible light wavelength range, but often exhibits some wavelength dependence. Therefore, even though the estimated wavelength shift amount around 724 nm differs from the wavelength shift amount in the shorter wavelength range, a uniform correction amount is used for correction, resulting in a problem where the correction error in the shorter wavelength range becomes large.

[0011] This invention has been made in view of the above technical background, and aims to provide an optical property measuring device, a wavelength shift correction device, a wavelength shift correction method, and a program that can accurately correct wavelength shifts across the entire wavelength range that can be dispersed by a spectroscopic means, even when a correction light source with a small number of independent emission line wavelengths is used, such as a neon lamp. [Means for solving the problem]

[0012] The above objectives will be achieved by the following means. (1) A spectroscopic means for dispersing incident light according to wavelength, A photoelectric conversion element having a plurality of pixels arranged in the dispersion direction of incident light by the spectroscopic means and receiving the dispersed incident light, Measuring means for measuring the wavelength and light quantity of incident light based on signals from each pixel of the photoelectric conversion element, When correcting the wavelength shift, the emission line wavelength of the incident light from the wavelength shift correction light source that emits light including emission lines of at least one wavelength within the wavelength range that can be dispersed by the spectroscopic means is the measured value when measured by the measuring means, and the difference from the original emission line wavelength of the correction light source is calculated as the emission line wavelength shift measurement quantity by the calculation means, The wavelength shift that occurs in the wavelength range that can be dispersed by the spectroscopic means A characteristic curve of a quantity, obtained by polynomial approximation of a characteristic curve determined by simulation or experiment, is used to determine a reference emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables. The coefficients of the polynomial are then modified using a linear function constructed based on the coefficients of the polynomial and the reference emission line wavelength shift, with the measured emission line wavelength shift as a variable. Coefficient determination means for When the coefficient is change The wavelength shift correction amount is obtained by the polynomial determined by the coefficient determination means, and the wavelength of the incident light measured by the measuring means is corrected by the wavelength shift correction amount by the correction means, Comprising Eta Optical property measuring device. (2) The optical property measuring device according to item 1 above, wherein the polynomial is a cubic equation. (3) The optical property measuring device according to item 1 or 2 above, which includes the wavelength shift correction light source. (4) Spectroscopic means for dispersing incident light according to wavelength, A photoelectric conversion element having a plurality of pixels arranged in the dispersion direction of incident light by the spectroscopic means and receiving the dispersed incident light, Measuring means for measuring the wavelength and light quantity of incident light based on signals from each pixel of the photoelectric conversion element, From an optical property measuring device comprising When correcting the wavelength shift, acquisition means for acquiring the measured value of the emission line wavelength of the incident light from the wavelength shift correction light source that emits light including emission lines of at least one wavelength within the wavelength range that can be dispersed by the spectroscopic means when measured by the measuring means, Calculation means for calculating the difference between the measured value acquired by the acquisition means and the original emission line wavelength of the correction light source as the emission line wavelength shift measurement quantity, The wavelength shift that occurs in the wavelength range that can be dispersed by the spectroscopic means A characteristic curve of a quantity, obtained by polynomial approximation of a characteristic curve determined by simulation or experiment, is used to determine a reference emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables. The coefficients of the polynomial are then modified using a linear function constructed based on the coefficients of the polynomial and the reference emission line wavelength shift, with the measured emission line wavelength shift as a variable. Coefficient determination means for comprising The wavelength shift correction amount obtained by the polynomial for which the coefficient is determined by the coefficient determination means corrects the wavelength of the incident light measured by the measurement means change A wavelength shift correction device. be (5) The wavelength shift correction device according to the previous item 4, wherein the polynomial is a cubic equation. (6) A measurement step of measuring the wavelength and light amount of incident light based on signals from a plurality of pixels of a photoelectric conversion element that is arranged in the dispersion direction of the wavelength of the incident light by the spectroscopic means and receives the dispersed incident light; When correcting the wavelength shift, the emission line wavelength of the incident light from the wavelength shift correction light source that emits light including an emission line of at least one wavelength within the wavelength range that can be dispersed by the spectroscopic means is the measurement value when measured by the measurement step, and A calculation step of calculating the difference from the original emission line wavelength of the correction light source as the emission line wavelength shift measurement amount; A coefficient determination step of causing a wavelength shift to occur in the wavelength range that can be dispersed by the spectroscopic means; A correction step of obtaining the wavelength shift correction amount by the polynomial for which the coefficient is determined by the coefficient determination step and correcting the wavelength of the incident light measured by the measurement step with the wavelength shift correction amount; A characteristic curve of a quantity, obtained by polynomial approximation of a characteristic curve determined by simulation or experiment, is used to determine a reference emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables. The coefficients of the polynomial are then modified using a linear function constructed based on the coefficients of the polynomial and the reference emission line wavelength shift, with the measured emission line wavelength shift as a variable. comprising A wavelength shift correction method. change (7) The wavelength shift correction method according to the previous item 6, wherein the polynomial is a cubic equation. (8) Spectroscopic means for dispersing incident light according to wavelength; waves A photoelectric conversion element having a plurality of pixels that are arranged in the dispersion direction of the incident light by the spectroscopic means and receive the dispersed incident light; Measurement means for measuring the wavelength and light amount of incident light based on signals from each pixel of the photoelectric conversion element; From an optical property measurement device comprising: [[ID= (31) When correcting the wavelength shift, an acquisition step of acquiring the measurement value when the measurement means measures the emission line wavelength of the incident light from the wavelength shift correction light source that emits light including an emission line of at least one wavelength within the wavelength range that can be dispersed by the spectroscopic means; ​​​A calculation step in which the difference between the measured value obtained in the acquisition step and the original emission line wavelength of the correction light source is calculated as the emission line wavelength shift measurement amount, Wavelength shift occurring in the wavelength range dispersible by the aforementioned spectroscopic means. A characteristic curve of a quantity, obtained by polynomial approximation of a characteristic curve determined by simulation or experiment, is used to determine a reference emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables. The coefficients of the polynomial are then modified using a linear function constructed based on the coefficients of the polynomial and the reference emission line wavelength shift, with the measured emission line wavelength shift as a variable. The coefficient determination step, Have the computer run it, The coefficient determined by the coefficient determination step is change The wavelength shift correction amount obtained by the aforementioned polynomial corrects the wavelength of the incident light measured by the measurement means. be program. (9) The program described in item 8 above, wherein the polynomial is a cubic polynomial. [Effects of the Invention]

[0013] According to the inventions described in paragraphs (1), (4), (6), and (8) above, the wavelength of incident light is measured based on signals from multiple pixels of photoelectric conversion elements arranged in the dispersion direction of incident light by the spectroscopic means. When correcting wavelength shift, the difference between the measured value of the emission line wavelength of incident light from a wavelength shift correction light source that emits light containing an emission line of at least one wavelength within the wavelength range dispersible by the spectroscopic means and the original emission line wavelength of the correction light source is calculated as the emission line wavelength shift measurement amount. On the other hand, wavelength shift occurring in the wavelength range dispersible by the spectroscopic means A characteristic curve of a quantity, obtained by polynomial approximation of a characteristic curve determined by simulation or experiment, is used to determine a reference emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables. Furthermore, a linear function is used with the measured emission line wavelength shift as a variable and constructed based on the coefficients of the polynomial and the reference emission line wavelength shift, and the coefficients of the polynomial are changed. And the coefficient is change The wavelength of the incident light is corrected by the wavelength shift correction amount determined by the polynomial.

[0014] In other words, the characteristics of wavelength shift occurring in the wavelength range dispersible by the spectroscopic means are expressed by a polynomial of linearity or higher with wavelength or wavelength-related parameters as variables, and correction is performed based on this polynomial. Therefore, even when a neon lamp is used as the light source for wavelength shift correction, not only the wavelength shift around the emission line wavelength of 724 nm but also the wavelength shift in the shorter wavelength range can be corrected with high accuracy, and the wavelength shift can be corrected with high accuracy across the entire wavelength range dispersible by the spectroscopic means. Moreover, since the emission line wavelength shift measurement amount and emission line wavelength shift reference amount are determined from one emission line wavelength of the light source for wavelength shift correction, and each coefficient of the polynomial is determined, it can be used without problems even if the number of independent emission line wavelengths as the light source for wavelength shift correction is small.

[0016] Previous item ( 2 )( 5 )( 7 ) and ( 9 According to the invention described above, since the polynomial is a cubic polynomial, it can faithfully represent the characteristics of wavelength shift that occur in the wavelength range that can be dispersed by the spectroscopic means.

[0017] Previous item ( 3 According to the invention described above, since the optical characteristic measuring device is equipped with a light source for wavelength shift correction, the user can perform wavelength shift correction operations without having to prepare a separate light source for wavelength shift correction. [Brief explanation of the drawing]

[0018] [Figure 1] This is a block diagram showing an example of the configuration of an optical property measuring device according to one embodiment of the present invention. [Figure 2] This diagram shows the optical path when light from a neon lamp is incident through the entrance slit as a light source for wavelength shift correction. [Figure 3] This figure shows an example of the spectrum of a neon lamp. [Figure 4] This figure shows an example of the output of a photoelectric conversion element when measuring the light from a neon lamp. [Figure 5]This figure shows the wavelength shift for several optical components, as determined by optical simulation. [Figure 6] This figure shows an excerpt and magnified view of one of the wavelength shifts of the optical components shown in Figure 5. [Figure 7] This figure shows the experimental results of measuring the wavelength shift at each wavelength when the optical property measuring device was changed from room temperature. [Modes for carrying out the invention]

[0019] Hereinafter, embodiments of this invention will be described based on the drawings.

[0020] Figure 1 is a block diagram showing an example of the configuration of an optical property measuring device according to one embodiment of the present invention.

[0021] This optical property measuring device 1 comprises an incident slit 2 into which light from the object to be measured is incident, a lens 3, a reflective diffraction grating 4 which is a spectral means, an image sensor (also simply called a sensor) 5 which is a photoelectric conversion element, a wavelength measuring unit 6, a correction unit 7, and a display unit 8.

[0022] Light entering through the entrance slit 2 enters the lens 3, where it is converted into nearly parallel light before entering the diffraction grating 4. The diffraction grating 4 disperses the light that enters through the entrance slit 2 and passes through the lens 3 according to its wavelength. The incident light is diffracted at different angles according to its wavelength by the diffraction grating 4, then focused again by the lens 3, and images are formed on the light-receiving surface of the sensor 5 at different positions according to their wavelength.

[0023] Sensor 5 has multiple pixels arranged in the direction of light dispersion by the diffraction grating 4, which receive the dispersed light, and outputs a signal corresponding to the amount of light received by each pixel. In this embodiment, sensor 5 has 40 pixels along the direction of light dispersion by the diffraction grating 4, and can measure the distribution of light intensity in the dispersion direction. Reference numeral 51 denotes the substrate on which the sensor is mounted.

[0024] The wavelength measurement unit 6 measures the wavelength (spectral spectrum) of light emitted from the object being measured based on the light received data at each pixel of the sensor 5.

[0025] The correction unit 7 calculates the wavelength shift correction amount in correction mode and corrects the wavelength shift amount measured by the wavelength measurement unit 6. The correction method will be described later.

[0026] The wavelength measurement unit 6 and the correction unit 7 may be composed of a CPU, a ROM in which the CPU's operating program is stored, and a arithmetic unit that includes RAM or the like, which serves as a working area when the CPU operates according to the operating program.

[0027] The display unit 8 displays the measurement results from the wavelength measurement unit 6, or the corrected measurement results if the wavelength shift has been corrected by the correction unit 7.

[0028] Incidentally, due to changes in the position of optical components such as the diffraction grating 4, lens 3, and sensor 5 over time, the wavelength actually measured may fluctuate, meaning a wavelength shift may occur, which results in a measurement error.

[0029] Therefore, in this embodiment, the optical characteristic measuring device 1 is equipped with a wavelength shift correction light source that emits emission lines of independent wavelengths, such as a neon lamp, and is capable of correcting wavelength shift in wavelength shift correction mode.

[0030] As shown in Figure 2, when light from the neon lamp 10 is incident through the incident slit 2 as a light source for wavelength shift correction, an image of the slit is formed on the sensor 5 at a position corresponding to the emission line wavelength of the neon lamp 10. Figure 3 shows an example of the spectrum of the neon lamp (Ne lamp) 10. As mentioned above, the neon lamp 10 has a somewhat independent emission line around 724 nm that can be used for wavelength estimation.

[0031] Figure 4 shows an example of the output of sensor 5 when measuring the light from neon lamp 10. By obtaining an output like the one shown in Figure 4, it is possible to determine which pixel of sensor 5 is incident on by the emission line of neon lamp 10 using the calculation method described in Patent Document 2. The initial wavelength is obtained from the output of sensor 5 when the light from neon lamp 10 is incident, and the wavelength shift amount is determined by comparing the wavelength measured during correction measurement with the initial wavelength.

[0032] However, with this method, while the amount of wavelength shift near the emission line wavelength of the neon lamp 10 can be estimated, it is not possible to determine the amount of wavelength shift over the entire wavelength range within the measurement range, or in other words, the wavelength range that is dispersed by the diffraction grating 4 and received by the sensor 5.

[0033] Therefore, in this embodiment, the following method is employed to accurately estimate the amount of wavelength shift not only near the emission line wavelength of the neon lamp 10, but also across the entire wavelength range that is dispersed by the diffraction grating 4 and received by the sensor 5. [Correction Example 1] The wavelength shifts that occur when the position or tilt of each optical component mounted on the optical properties measuring device 1 changes are determined in advance through optical simulations and accelerated tests. Figure 5 shows the wavelength shifts for several optical components determined by optical simulations. The horizontal axis represents the pixel numbers of the 40 pixels, and the vertical axis represents the amount of wavelength shift. The optical elements with particularly high error sensitivity are the rotation of the diffraction grating 4 in the dispersion direction and the positional displacement of the lens 3 and sensor 5 in the dispersion direction. However, for all of these elements, the larger the pixel number, in other words, the longer the wavelength, the smaller the wavelength shift.

[0034] In this embodiment, the emission line (724 nm) of the neon lamp 10 is incident between pixel numbers 38 and 39. Therefore, in order to correct the wavelength shift caused by the misalignment of the positions and orientations of these optical elements, it is necessary to apply a larger correction to the pixel numbers on the shorter wavelength side than the amount of wavelength shift estimated by measuring the emission line of the neon lamp 10.

[0035] In this embodiment, it is assumed that the occurrence of wavelength shift over time depends on the rotation of the diffraction grating α with the largest wavelength shift, as shown in Figure 5, and a correction formula is derived.

[0036] Figure 6 shows an enlarged and extracted characteristic curve of wavelength shift due to the change in the tilt of the diffraction grating α, taken from Figure 5. If the parameter x is the pixel number on the horizontal axis and the wavelength shift amount y(x) is the amount of wavelength shift on the vertical axis, then the wavelength shift amount y(x) in the characteristic curve shown in Figure 6 can be approximated by a cubic function of the pixel number x and is expressed by the following cubic equation (1).

[0037] y(x) = -1.52477 × 10 -5 x 3 +1.26376 × 10 -3 x 2 -4.56637 × 10 -2 x+6.04060 ····(1) However, x: pixel number, y(x): wavelength shift (nm) For example, if pixel number 38 receives light with a centroid wavelength of 720 nm and pixel number 39 receives light with a centroid wavelength of 728 nm, the 724 nm emission line of the neon lamp 10 will be imaged exactly between pixels 38 and 39. Therefore, the reference amount of emission line wavelength shift due to the change in the tilt of the diffraction grating α, which can be obtained from equation (1), is y(38.5) = 5.2856 (nm) by substituting x = 38.5 into equation (1).

[0038] When actually performing wavelength shift correction using the neon lamp 10, it is possible to measure the wavelength of the emission line of the neon lamp 10 and calculate the emission line wavelength shift measurement amount, which is the difference between the measured value and the emission line wavelength. However, there are no known values ​​other than the emission line wavelength shift reference amount and the emission line wavelength shift measurement amount. Therefore, it is necessary to determine each coefficient in equation (1) using the emission line wavelength shift reference amount and the emission line wavelength shift measurement amount of the neon lamp 10. Each coefficient in equation (1) is the coefficient of the approximate formula when the emission line wavelength shift measurement amount of the neon lamp 10 is equal to the emission line wavelength shift reference amount of 5.2856 nm.

[0039] The amount of wavelength shift with respect to the change in the inclination of the diffraction grating α is approximately proportional to the amount of inclination regardless of the wavelength. From this, if the amount of measured emission line wavelength shift of the neon lamp 10 can be calculated, each coefficient of Equation (1) may be made proportional to the amount of measured emission line wavelength shift of the neon lamp 10. Therefore, an approximate equation for the amount of wavelength shift at an arbitrary wavelength is expressed as a cubic equation, y(x)=ax 3 +bx 2 +cx+d ···(2) and when the amount of measured emission line wavelength shift by the neon lamp 10 is ΔλNe (unit: nm), if each coefficient of Equation (2) is set as in the following Equations (3) to (5), the amount of wavelength shift generated by the change in the inclination of the diffraction grating α can be approximated for the pixels of all pixel numbers.

[0040] a=-1.52477×10 -5 / 5.2856×ΔλNe ···(3) b=1.26376×10 -3 / 5.2856×ΔλNe ···(4) c=-4.56637×10 -2 / 5.2856×ΔλNe ···(5) d=6.04060 / 5.2856×ΔλNe ···(6) Thus, each coefficient of the approximate equation is obtained, and then for the measured value λ(x) of the wavelength measured at the pixels of each pixel number of the sensor 5, the amount of wavelength shift y(x) of the wavelength is obtained. Using this amount of wavelength shift y(x) as a correction amount, the wavelength λ’(x) at each pixel number after correction is obtained by the following correction equation (7).

[0041] λ’(x)= λ(x)-y(x) ···(7) In this embodiment, when correcting wavelength shift, a wavelength shift measurement is calculated, which is the difference between the measured value of the emission line wavelength of the incident light from the neon lamp 10 used for wavelength shift correction and the original emission line wavelength of the neon lamp 10. On the other hand, a reference emission line wavelength shift amount for the same emission line wavelength as the neon lamp 10 is calculated using a third-order polynomial that expresses the characteristics of wavelength shift occurring in the wavelength range dispersed by the diffraction grating 4 and received by the sensor 5, with the pixel number as a variable. The coefficients of the polynomial are then determined from these emission line wavelength shift measurement amounts and emission line wavelength shift reference amounts. The wavelength of the incident light is then corrected by the wavelength shift correction amount obtained from the polynomial with the determined coefficients.

[0042] In other words, the characteristics of the wavelength shift that occurs in the wavelength range dispersed by the diffraction grating 4 and received by the sensor 5 are represented by a third-order polynomial with the pixel number as a variable, and correction is performed based on this polynomial. Therefore, even when a neon lamp 10 is used as a light source for wavelength shift correction, not only the wavelength shift around the emission line wavelength of 724 nm but also the wavelength shift in the shorter wavelength range can be corrected with high accuracy, and the wavelength shift can be corrected with high accuracy across the entire wavelength range dispersed by the diffraction grating 4 and received by the sensor 5. Moreover, since the emission line wavelength shift measurement amount and emission line wavelength shift reference amount are determined from one emission line wavelength of the neon lamp 10, and each coefficient of the polynomial is determined, neon lamps 10 and the like, which have a small number of independent emission line wavelengths, can be used as a light source for wavelength shift correction without any problems.

[0043] In the above correction example 1, the wavelength shift was considered for the diffraction grating α, but the same method can be applied to other optical components. [Correction Example 2] Next, we will explain other examples of wavelength shift correction.

[0044] In correction example 1, the coefficients a, b, c, and d of the cubic equation (2) were determined based on the characteristic curve of the wavelength shift obtained by simulation of the optical component, but the characteristic curve can also be determined experimentally.

[0045] Figure 7 is a graph showing the experimental results of wavelength shift at each wavelength when the optical property measuring device 1 was subjected to a temperature change from room temperature. This wavelength shift is caused by the shift in the position and tilt of the optical components due to the temperature change. Optical components whose position and tilt change with temperature are likely to undergo similar changes over time. In other words, it is expected that the wavelength shift will follow a similar trend to that shown in Figure 7 over time. In Figure 7, the horizontal axis represents wavelength, and the vertical axis represents the amount of wavelength shift.

[0046] If we let the wavelength be λ on the horizontal axis and the wavelength shift amount be y(λ) on the vertical axis, the wavelength shift amount y(λ) in the wavelength shift characteristic curve shown in Figure 7 can be approximated by a cubic function of wavelength λ and is expressed by the following cubic equation (8).

[0047] y(λ) = -7.20085 × 10 -9 λ 3 +1.19511 × 10 -5 λ 2 -6.21323 × 10 -3 λ + 7.98425 × 10 -1 ...(8) However, λ: wavelength (nm), y(λ): wavelength shift (nm) Substituting the emission line λ = 724 (nm) of neon lamp 10 due to temperature change during the experiment shown in Figure 7 into equation (8), the reference quantity for emission line wavelength shift is y(724) = -0.168 (nm).

[0048] Similar to Correction Example 1, the approximate formula for the wavelength shift amount for any wavelength is a cubic equation. y(λ)=aλ 3 +bλ 2 +cλ+d ···(9) When expressed as ΔλNe (unit: nm) for the emission line wavelength shift measured by the neon lamp 10, the following coefficients in equation (9) will approximate the wavelength shift caused by temperature changes at any given wavelength.

[0049] a = -7.20085 × 10 -9 / (-0.168)×ΔλNe ···(10) b = 1.19511 × 10 -5 / (-0.168)×ΔλNe ···(11) c = -6.21323 × 10 -3 / (-0.168)×ΔλNe ···(12) d=7.98425 / (-0.168)×ΔλNe ···(13) Thus, each coefficient of the approximation formula is determined, and then the wavelength shift amount y(λ) is calculated for each measured wavelength λ. This wavelength shift amount y(λ) is used as the correction amount, and the corrected wavelength λ' at each pixel number is calculated using the following correction formula (14).

[0050] λ' = λ - y(λ) ···(14) Thus, in this embodiment as well, the wavelength shift characteristic occurring in the wavelength range dispersed by the diffraction grating 4 and received by the sensor 5 is corrected using a cubic equation with wavelength as a variable. Therefore, even when a neon lamp 10 is used as the light source for wavelength shift correction, wavelength shifts in shorter wavelength ranges can be corrected with high accuracy, similar to the correction of wavelength shifts around 724 nm. This allows for accurate correction of wavelength shifts across the entire wavelength range dispersed by the diffraction grating 4 and received by the sensor 5. Moreover, since the emission line wavelength shift measurement amount and emission line wavelength shift reference amount are determined from one emission line wavelength of the neon lamp 10, and each coefficient of the polynomial is determined, a neon lamp 10 with a small number of independent emission line wavelengths can be used as the light source for wavelength shift correction.

[0051] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in Correction Example 1, the pixel number was used as a parameter related to wavelength, but the wavelength may be used as a variable, as in Correction Example 2. Furthermore, the parameter related to wavelength is not limited to the pixel number.

[0052] Furthermore, while the wavelength shift characteristics were approximated by a cubic equation with wavelength or wavelength-related parameters as variables, they may also be approximated by a linear equation, a quadratic equation, or a polynomial of degree 4 or higher, depending on the characteristics of each component.

[0053] Furthermore, although a neon lamp 10 was used as the light source for wavelength shift correction, any light source that emits light containing emission lines of at least one wavelength can be used as the light source for wavelength shift correction.

[0054] Furthermore, although the case where a neon lamp 10, which is a light source for wavelength shift correction, is provided in the optical characteristic measuring device 1 has been described, it is not necessary for it to be provided. However, it is preferable if it is provided, as it allows the user to perform wavelength shift correction operations without having to prepare a separate light source for wavelength shift correction.

[0055] Furthermore, although the optical characteristic measuring device 1 incorporates a correction unit 7 to correct wavelength shift within the device itself, the correction of wavelength shift may also be performed using a correction device consisting of a personal computer or the like located outside the optical characteristic measuring device 1. In this case, the correction device should acquire the emission line wavelength measurement results for the light source for wavelength shift correction from the optical characteristic measuring device 1, calculate the emission line wavelength shift measurement amount, and determine the coefficients of the polynomial. Alternatively, the calculation of the wavelength shift correction amount using the polynomial after the coefficient determination and the correction of the measured wavelength may be performed on the correction device side, or the polynomial with the determined coefficients may be transmitted to the optical characteristic measuring device 1, and the optical characteristic measuring device 1 may use the received polynomial to calculate and correct the wavelength shift correction amount.

[0056] The polynomial representing the wavelength shift characteristics may be pre-stored in the optical properties measuring device 1 or the correction device, or it may be retrieved from a separate storage location by the optical properties measuring device 1 or the correction device during the correction process.

[0057] This application is accompanied by a priority claim from Japanese Patent Application No. 2021-004965, filed on January 15, 2021, and the disclosures thereof constitute a part of this application. [Industrial applicability]

[0058] This invention can be used as an optical property measuring device that measures wavelength by spectrally analyzing incident light, such as a spectrophotometer or spectroluminometer. [Explanation of Symbols]

[0059] 1 Optical property measuring device 2. Entrance slit 3 lenses 4. Diffraction grating (spectroscopy means) 5. Sensor (Photoelectric conversion element) 6 Wavelength measurement section 7. Correction Unit 8 Display 10. Light source for wavelength shift correction

Claims

1. A spectroscopic means for dispersing incident light according to wavelength, A photoelectric conversion element having a plurality of pixels arranged in the dispersion direction of incident light by the spectral means and receiving the dispersed incident light, A measuring means for measuring the wavelength and intensity of incident light based on signals from each pixel of the photoelectric conversion element, In correcting wavelength shift, a calculation means calculates the difference between the measured value of the emission line wavelength of incident light from a wavelength shift correction light source that emits light containing an emission line of at least one wavelength within the wavelength range dispersible by the spectral means, measured by the measurement means, and the original emission line wavelength of the correction light source, as the emission line wavelength shift measurement amount. A coefficient determination means that determines a reference amount of wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial obtained by approximating the characteristic curve of the wavelength shift amount generated in the wavelength range dispersible by the spectroscopic means, which is determined by simulation or experiment, and which has wavelength or wavelength-related parameters as variables, and modifies the coefficient of the polynomial using a linear function constructed based on the coefficient of the polynomial and the reference amount of wavelength shift, with the measured amount of emission line wavelength shift as a variable, A correction means that determines a wavelength shift correction amount using the polynomial whose coefficient has been changed by the coefficient determination means, and corrects the wavelength of the incident light measured by the measurement means by the wavelength shift correction amount, An optical properties measuring device equipped with the necessary components.

2. The optical property measuring device according to claim 1, wherein the aforementioned polynomial is a cubic polynomial.

3. The optical property measuring apparatus according to claim 1 or 2, further comprising the light source for wavelength shift correction.

4. A spectroscopic means for dispersing incident light according to wavelength, A photoelectric conversion element having a plurality of pixels arranged in the dispersion direction of incident light by the spectral means and receiving the dispersed incident light, A measuring means for measuring the wavelength and intensity of incident light based on signals from each pixel of the photoelectric conversion element, From an optical properties measuring device equipped with, In correcting wavelength shift, an acquisition means acquires a measurement value when the measurement means measures the emission line wavelength of incident light from a wavelength shift correction light source that emits light containing an emission line of at least one wavelength within the wavelength range dispersible by the spectral means. A calculation means that calculates the difference between the measured value obtained by the acquisition means and the original emission line wavelength of the correction light source as the emission line wavelength shift measurement amount, A coefficient determination means that determines a reference amount of wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial obtained by approximating the characteristic curve of the wavelength shift amount generated in the wavelength range dispersible by the spectroscopic means, which is determined by simulation or experiment, and which has wavelength or wavelength-related parameters as variables, and modifies the coefficient of the polynomial using a linear function constructed based on the coefficient of the polynomial and the reference amount of wavelength shift, with the measured amount of emission line wavelength shift as a variable, Equipped with, A wavelength shift correction device in which the wavelength of incident light measured by the measuring means is corrected by a wavelength shift correction amount obtained by the polynomial whose coefficient has been changed by the coefficient determination means.

5. The wavelength shift correction device according to claim 4, wherein the aforementioned polynomial is a cubic polynomial.

6. A measurement step in which the wavelength and light intensity of incident light are measured based on signals from multiple pixels of a photoelectric conversion element that are arranged in the dispersion direction of the wavelength of the incident light by a spectroscopic means and receive the dispersed incident light, In correcting wavelength shift, a calculation step is performed to calculate the difference between the measured value obtained by the measurement step when measuring the emission line wavelength of incident light from a wavelength shift correction light source that emits light containing an emission line of at least one wavelength within the wavelength range dispersible by the spectral means, and the original emission line wavelength of the correction light source, as the emission line wavelength shift measurement amount. A characteristic curve of the wavelength shift amount generated in the wavelength range dispersible by the spectroscopic means, obtained by polynomial approximation of the characteristic curve determined by simulation or experiment, is used to determine a reference amount of emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables, and a coefficient determination step is performed to change the coefficient of the polynomial using a linear function constructed based on the coefficient of the polynomial and the reference amount of emission line wavelength shift, with the measured amount of emission line wavelength shift as a variable. A correction step in which the wavelength shift correction amount is determined by the polynomial whose coefficients have been changed by the coefficient determination step, and the wavelength of the incident light measured by the measurement step is corrected by the wavelength shift correction amount, A wavelength shift correction method equipped with [a specific feature].

7. The wavelength shift correction method according to claim 6, wherein the aforementioned polynomial is a cubic polynomial.

8. A spectroscopic means for dispersing incident light according to wavelength, A photoelectric conversion element having a plurality of pixels arranged in the dispersion direction of incident light by the spectral means and receiving the dispersed incident light, A measuring means for measuring the wavelength and intensity of incident light based on signals from each pixel of the photoelectric conversion element, From an optical properties measuring device equipped with, In correcting wavelength shift, the measurement means obtains a measurement value when it measures the emission line wavelength of incident light from a wavelength shift correction light source that emits light containing an emission line of at least one wavelength within the wavelength range dispersible by the spectral means. A calculation step in which the difference between the measured value obtained in the acquisition step and the original emission line wavelength of the correction light source is calculated as the emission line wavelength shift measurement amount, A characteristic curve of the wavelength shift amount generated in the wavelength range dispersible by the spectroscopic means, obtained by polynomial approximation of the characteristic curve determined by simulation or experiment, is used to determine a reference amount of emission line wavelength shift for the same emission line wavelength as the light source for wavelength shift correction, using a polynomial with wavelength or wavelength-related parameters as variables, and a coefficient determination step is performed to change the coefficient of the polynomial using a linear function constructed based on the coefficient of the polynomial and the reference amount of emission line wavelength shift, with the measured amount of emission line wavelength shift as a variable. Have the computer run it, A program in which the wavelength of incident light measured by the measuring means is corrected by a wavelength shift correction amount obtained by the polynomial whose coefficient has been changed in the coefficient determination step.

9. The program according to claim 8, wherein the aforementioned polynomial is a cubic polynomial.

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