Spectral measurement device

Abstract

A spectral measurement device includes: an optical band-pass filter section that has first to n-th wavelengths (n is an integer of 2 or more) having a predetermined wavelength width as a spectral band thereof; a correction operation section that corrects a reception signal based on an output optical signal from the optical band-pass filter section; and a signal processing section that executes predetermined signal processing based on the reception signal corrected by the correction operation section that corrects the reception signal based on the change in the spectral distribution of the reception signal.

1 . A spectral measurement device comprising:
 an optical band-pass filter section that has first to n-th wavelengths (n is an integer of 2 or more) having a predetermined wavelength width as a spectral band thereof;   a light receiving section that receives light from the optical band-pass filter section;   a correction operation section that performs an operation to correct a reception signal obtained from the light receiving section; and   a signal processing section that executes predetermined signal processing based on the reception signal corrected by the correction operation section,   wherein the correction operation section corrects the reception signal based on a change in a spectral distribution of the reception signal.   
     
     
         2 . The spectral measurement device according to  claim 1 ,
 wherein the correction operation section calculates a second derivative of a characteristic line representing the spectral distribution of the reception signal, decreases the value of the reception signal through the correction when the second derivative is positive, and increases the value of the reception signal through the correction when the second derivative is negative.   
     
     
         3 . The spectral measurement device according to  claim 2 ,
 wherein the correction operation section controls a correction value used for the correction variably based on the magnitude of an absolute value of the second derivative.   
     
     
         4 . The spectral measurement device according to  claim 2 ,
 wherein when a reception light intensity of a first spectral band is p 1 , a reception light intensity of a second spectral band adjacent to the first spectral band is p 2 , and a reception light intensity of a third spectral band adjacent to the second spectral band is p 3 , the correction operation section calculates a second derivative Q 1  through an operation based on Q 1 =(p 1 +p 3 −2·p 2 ) and calculates a correction value used for the correction of the reception light intensity p 2  of the second spectral band through an operation based on the calculated second derivative Q 1  and a correction coefficient k 1  (k 1  is a real number).   
     
     
         5 . The spectral measurement device according to  claim 1 ,
 wherein when, among the first to n-th wavelengths, an m-th wavelength band (1≦m≦n and m is an integer) is an interest wavelength band, and a k-th wavelength band (k≠m, 1≦k≦n, and k is an integer) other than the m-th wavelength band is a non-interest wavelength band, the optical band-pass filter section functions as an m-th band-pass filter corresponding to the m-th wavelength band and also functions as a k-th band-pass filter corresponding to the k-th wavelength band,   the correction operation section further includes
 a noise estimation section that estimates the amount of the noise component for each wavelength band of the k-th wavelength band included in an interest reception signal obtained by the light receiving section receiving transmission light or reflection light of the m-th band-pass filter corresponding to the m-th wavelength band, and 
 a noise removal and correction section that performs correction of subtracting the sum of the estimated noise component for each wavelength band from the interest reception signal and 
   the correction operation section executes correction of the reception signal by the noise estimation section and the noise removal and correction section and then executes the correction based on the change in the spectral distribution of the reception signal.   
     
     
         6 . The spectral measurement device according to  claim 5 ,
 wherein when the interest reception signal obtained by the light receiving section receiving the transmission light or reflection light of the m-th band-pass filter is Sm,   a non-interest reception signal obtained by the light receiving section receiving the transmission light or reflection light of the k-th band-pass filter is Sk,   a transmittance or a reflectance in the k-th wavelength band of the m-th band-pass filter is P(m,k),   a transmittance or a reflectance in the k-th wavelength band of the k-th band-pass filter is P(k,k), and   a noise component for each wavelength band of the k-th wavelength band included in the interest reception signal sm is N(m,k),   the noise estimation section performs an operation based on Formula (1) below to estimate the amount of the noise component for each wavelength band of the k-th wavelength band included in the interest reception signal Sm
     N ( m,k )= Sk·{P ( m,k )/ P ( k,k )}  (1), and
 
   the noise removal and correction section calculates the sum ΣN(m,k) of the estimated noise component N(m,k) for each wavelength band and executes an operation based on Formula (2) below to obtain the corrected reception signal Smc.
     Smc=Sm−ΣN ( m,k )  (2)
 
   
     
     
         7 . The spectral measurement device according to  claim 6 ,
 wherein when the sum of transmittance or reflectance of all of the wavelength bands of the m-th band-pass filter is ΣQm(1˜n),   the sum of transmittance or reflectance of all of the wavelength bands of the k-th band-pass filter is ΣQk(1˜n), and   a correction coefficient for correcting a difference in the transmittance properties or reflectance properties between filters is R (=ΣQm(1˜n)/ΣQk(1˜n)),   the noise estimation section performs an operation based on Formula (3) below to estimate the amount of the noise component for each wavelength band of the k-th wavelength band included in the interest reception signal Sm.
     N ( m,k )= Sk·{P ( m,k )/ P ( k,k )}· R   (3)
 
   
     
     
         8 . The spectral measurement device according to  claim 1 ,
 wherein the optical band-pass filter section is a variable gap etalon filter.   
     
     
         9 . The spectral measurement device according to  claim 1 ,
 wherein the signal processing section measures a spectrophotometric distribution of a measurement target sample based on the reception signal corrected by the correction value.