Optical characteristic measuring apparatus, wavelength shift correcting apparatus, wavelength shift correction method, and program

1 . An optical characteristic measuring apparatus comprising:

a diffraction grating to disperse incident light according to a wavelength;

a photoelectric conversion sensor including a plurality of pixels arranged in a dispersion direction in which the incident light is dispersed by the diffraction grating, the pixels to receive the dispersed incident light; and

a hardware processor to:

measure the wavelength of the incident light and a light amount of the incident light based on a signal from each of the pixels of the photoelectric conversion sensor;

in correction of a shift in wavelength, calculate, as a measured amount of shift in emission line wavelength, a difference between a measured value obtained when the hardware processor measures the emission line wavelength of the incident light from a light source for wavelength shift correction that emits the light including an emission line at at least one wavelength in a range of wavelengths into which the light can be dispersed by the diffraction grating and an original emission line wavelength of the light source for correction;

determine each coefficient of a polynomial based on a reference amount of shift in emission line wavelength for the same emission line wavelength as the emission line wavelength of the light source for wavelength shift correction and the measured amount of shift in emission line wavelength calculated by the hardware processor, the polynomial being a first or higher order polynomial that has a variable indicating the wavelength or a parameter relating to the wavelength and represents a characteristic of a shift in wavelength that occurs in the range of wavelengths into which the light can be dispersed by the diffraction grating, the reference amount of shift in emission line wavelength being obtained using the polynomial;

obtain a wavelength shift correction amount by the polynomial, each coefficient of which is determined by the hardware processor; and

calibrate the optical characteristic measuring apparatus by correcting the wavelength of the incident light measured by the hardware processor with the wavelength shift correction amount,

wherein the polynomial is an equation made based on an amount of shift in wavelength which occurs when a position or inclination of an optical component and the photoelectric conversion sensor changes,

the amount of shift in wavelength is obtained by an optical simulation or obtained experimentally as the polynomial and stored-before measuring the emission line wavelength of the light source for wavelength shift correction, and

each coefficient of the polynomial determined by the hardware processor is represented by a linear function of the measured amount of shift in emission line wavelength.

2 . The optical characteristic measuring apparatus according to claim 1 , wherein the polynomial is a cubic polynomial.

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

4 . A wavelength shift correcting apparatus comprising:

a hardware processor to:

in correction of a shift in wavelength, obtain a measured value from an optical characteristic measuring apparatus including: a diffraction grating to disperse incident light according to a wavelength; a photoelectric conversion sensor including a plurality of pixels arranged in a dispersion direction in which the incident light is dispersed by the diffraction grating, the pixels to receive the dispersed incident light; and a hardware processor of the optical characteristic measuring apparatus to measure the wavelength of the incident light and a light amount of the incident light based on a signal from each of the pixels of the photoelectric conversion sensor, the measured value being obtained when the hardware processor of the optical characteristic measuring apparatus measures an emission line wavelength of the incident light from a light source for wavelength shift correction that emits the light including an emission line at at least one wavelength in a range of wavelengths into which the light can be dispersed by the diffraction grating;

calculate, as a measured amount of shift in emission line wavelength, a difference between the measured value obtained by the hardware processor of the wavelength shift correcting apparatus and an original emission line wavelength of the light source for correction; and

determine each coefficient of a polynomial based on a reference amount of shift in emission line wavelength for the same emission line wavelength as the emission line wavelength of the light source for wavelength shift correction and the measured amount of shift in emission line wavelength calculated by the hardware processor of the wavelength shift correcting apparatus, the polynomial being a first or higher order polynomial that has a variable indicating the wavelength or a parameter relating to the wavelength and represents a characteristic of a shift in wavelength that occurs in the range of wavelengths into which the light can be dispersed by the diffraction grating, the reference amount of shift in emission line wavelength being obtained using the polynomial,

wherein the wavelength of the incident light measured by the hardware processor of the optical characteristic measuring apparatus is obtained by the polynomial, each coefficient of which is determined by the hardware processor of the wavelength shift correcting apparatus,

the optical characteristic measuring apparatus is calibrated by correcting the wavelength of the incident light measured by the hardware processor of the wavelength shift correcting apparatus with the wavelength shift correction amount,

the polynomial is an equation made based on an amount of shift in wavelength which occurs when a position or inclination of an optical component and the photoelectric conversion sensor changes,

the amount of shift in wavelength is obtained by an optical simulation or obtained experimentally as the polynomial and stored before measuring the emission line wavelength of the light source for wavelength shift correction, and

each coefficient of the polynomial determined by the hardware processor is represented by a linear function of the measured amount of shift in emission line wavelength.

5 . The wavelength shift correcting apparatus according to claim 4 , wherein the polynomial is a cubic polynomial.

6 . A wavelength shift correction method comprising:

measuring a wavelength and a light amount of incident light based on signals from a plurality of pixels of a photoelectric conversion sensor, the pixels being arranged in a dispersion direction in which the incident light is dispersed by a diffraction grating, the pixels to receive the dispersed incident light;

in correction of a shift in wavelength, calculating, as a measured amount of shift in emission line wavelength, a difference between a measured value obtained when the emission line wavelength of the incident light from a light source for wavelength shift correction that emits the light including an emission line at at least one wavelength in a range of wavelengths into which the light can be dispersed by the diffraction grating is measured and an original emission line wavelength of the light source for correction;

determining each coefficient of a polynomial based on a reference amount of shift in emission line wavelength for the same emission line wavelength as the emission line wavelength of the light source for wavelength shift correction and the measured amount of shift in emission line wavelength that is calculated, the polynomial being a first or higher order polynomial that has a variable indicating the wavelength or a parameter relating to the wavelength and represents a characteristic of a shift in wavelength that occurs in the range of wavelengths into which the light can be dispersed by the diffraction grating, the reference amount of shift in emission line wavelength being obtained using the polynomial; and

obtaining a wavelength shift correction amount by the polynomial, each coefficient of which is determined in the coefficient of which is determined; and

calibrating the optical characteristic measuring apparatus by correcting the wavelength of the incident light measured by the hardware processor with the wavelength shift correction amount,

wherein the polynomial is an equation made based on an amount of shift in wavelength which occurs when a position or inclination of an optical component and the photoelectric conversion sensor changes,

the amount of shift in wavelength is obtained by an optical simulation or obtained experimentally as the polynomial and stored before measuring the emission line wavelength of the light source for wavelength shift correction, and

each coefficient of the polynomial determined by the hardware processor is represented by a linear function of the measured amount of shift in emission line wavelength.

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

8 . A non-transitory computer-readable recording medium storing a program for causing a computer to execute:

in correction of a shift in wavelength, obtaining a measured value from an optical characteristic measuring apparatus including: a diffraction grating to disperse incident light according to a wavelength, a photoelectric conversion sensor including a plurality of pixels arranged in a dispersion direction in which the incident light is dispersed by the diffraction grating, the pixels to receive the dispersed incident light, and a hardware processor to measure the wavelength of the incident light and a light amount of the incident light based on a signal from each of the pixels of the photoelectric conversion sensor the measured value being obtained when the hardware processor measures an emission line wavelength of the incident light from a light source for wavelength shift correction that emits the light including an emission line at at least one wavelength in a range of wavelengths into which the light can be dispersed by the diffraction grating;

calculating, as a measured amount of shift in emission line wavelength, a difference between the measured value that is obtained and an original emission line wavelength of the correction light source; and

determining each coefficient of a polynomial based on a reference amount of shift in emission line wavelength for the same emission line wavelength as the emission line wavelength of the light source for wavelength shift correction and the measured amount of shift in emission line wavelength that is calculated, the polynomial being a first or higher order polynomial that has a variable indicating the wavelength or a parameter relating to the wavelength and represents a characteristic of a shift in wavelength that occurs in the range of wavelengths into which the light can be dispersed by the diffraction grating, the reference amount of shift in emission line wavelength being obtained using the polynomial,

wherein the wavelength of the incident light measured by the hardware processor of the optical characteristic measuring apparatus is obtained by the polynomial, each coefficient of which is determined,

the polynomial is an equation made based on an amount of shift in wavelength which occurs when a position or inclination of an optical component and the photoelectric conversion sensor changes,

the amount of shift in wavelength is obtained by an optical simulation or obtained experimentally as the polynomial and stored before measuring the emission line wavelength of the light source for wavelength shift correction, and

each coefficient of the polynomial determined by the hardware processor is represented by a linear function of the measured amount of shift in emission line wavelength.

9 . The non-transitory computer-readable recording medium storing the program according to claim 8 , wherein the polynomial is a cubic polynomial.