JPH0211848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color measuring device suitable for samples that emit fluorescence.

The basic method of measuring the color of a sample is to measure the spectral reflectance of the sample. By calculating the stimulation value of each of the three primary colors from the spectral reflectance, the color of the sample can be displayed numerically. The present invention relates to a part that measures spectral reflectance in the above-mentioned colorimetry.

The measurement of spectral reflectance in colorimetry usually uses a standard white plate, and a standard white plate (e.g.
A white plate (pressed BaSO ₄ powder) and the sample are illuminated, and the ratio Rt(λ) of the intensity of reflected light from the sample to the intensity of reflected light from the standard white plate is determined by changing the wavelength λ. Rt (λ) is called the spectral reflection radiance factor. By multiplying this Rt (λ) by the absolute spectral reflectance of the standard white plate, the absolute spectral reflectance of the sample can be determined. However, if the sample is a substance that emits fluorescence, the spectral reflectance Rt (λ) obtained as described above is generally the true spectral reflection radiance factor Rt.
(λ) and the fluorescence radiance factor Rf (λ), Rt (λ) = Rr (λ) + Rf (λ) (1). Here, the radiance factor is the intensity of the light coming from the sample divided by the intensity of the light coming from the standard white plate.The standard white plate does not emit any fluorescence, and the light coming from the standard white plate is reflected. However, since the light coming from the sample is generally composed of reflected light and fluorescent light, there is a radiance factor for each. In the above equation, λ is the wavelength of the illumination light, and fluorescent light generally appears at the same wavelength as the illumination light or at a longer wavelength. Raman rays should be treated in the same way as fluorescence in colorimetry, and they also appear on the shorter wavelength side than illumination light. Therefore, the fluorescence radiance factor for light having the same wavelength as the illumination light is not necessarily zero. When a fluorescent sample is illuminated with light of wavelength λ, the spectrum of the apparent reflected light from the sample is generally drawn as shown in Figure 1. In this figure, λ is the center wavelength of the illumination light, and the reason why a high peak P appears at λ is of course due to reflection by the sample. Below this peak, low peaks F distributed on both sides of λ represent fluorescence. If we connect these fluorescence peaks F flatly like a dotted line at the peak at wavelength λ, this is the fluorescence spectrum when the sample is illuminated with light at wavelength λ, and the peak P on this spectrum is The height H of is the true reflected light at wavelength λ. However, in conventional colorimetry, the illumination light wavelength λ
It was not possible to measure the apparent reflected light separately into the true reflected light component and the fluorescent light component. H
is the true spectral reflection radiance factor in equation (1) above.
Rr(λ), and =H'-H gives the fluorescence radiance factor Rf(λ).

The object of the present invention is to provide a colorimeter that can separate and measure the apparent spectral reflection of a sample into the true spectral reflection and fluorescence. The color of a sample can be determined as the spectral distribution of reflected light obtained by multiplying the spectral reflectance of the sample and the spectral distribution of illumination light by the corresponding wavelengths, but if the sample emits fluorescence, the fluorescence is Since it depends on the spectral distribution of light, multiplying the apparent spectral reflectance and the spectral distribution of the illumination light source by the corresponding wavelengths will not yield the correct spectral distribution of the sample color, but rather the actual color and apparent spectral distribution. There may be cases where the color is different from the color expected from the reflectance characteristics. According to the present invention, it becomes clear whether a sample emits fluorescent light or not, and the apparent reflected light is separated into true reflected light and fluorescent light. This provides data that allows us to predict the actual color under light.

FIG. 2 shows an embodiment of the present invention. M1 is an illumination light spectrometer for irradiating a sample with monochromatic light of an arbitrary wavelength, M2 is a reflected light spectrometer for separating light reflected from the sample, and I is an integrating sphere. Illumination light spectrometer M1
The light emitted from the sphere is made to enter the inner surface of the integrating sphere I. A window w is provided at a position different from the illumination light incident point on the integrating sphere, and the standard white plate W or the sample Sm is placed there. There is a light extraction hole h at a position facing the window w of the integrating sphere, and the light emitted from the hole is made to enter the reflected light spectrometer M2. S in the reflected light spectrometer M2
2 is an entrance slit, D is a multi-channel photometric element such as a photodiode array, and G2 is a concave diffraction grating.The light beam incident from the entrance slit S2 is reflected and diffracted by G2, and then a spectrum is formed on the light receiving surface of the photometric element D. An image is formed. Illumination light spectrometer M
1, wavelength scanning is performed in steps of 10 nm from an appropriate wavelength in the ultraviolet region, for example 300 nm, to the long wavelength end of 800 nm in the visible region. Color measurement is a problem only in the visible range, but since the present invention also targets samples that emit fluorescence, it is possible to measure colors in the ultraviolet range, which is contained in everyday light sources such as sunlight and can cause fluorescence in the visible range. Since this light cannot be ignored as illumination light, the illumination light spectrometer is designed to scan from the ultraviolet region to wavelengths at the red end. In the multi-channel photometric element D, outputs from unit elements at positions of 300 nm or more every 10 nm can be read from the spectral image formed on the element D.
Starting from the unit element on which 300 nm light is incident on the photometric element D, this is set as address 0, and 1,
Number them 2, 3, etc. Specifically, even one address includes several unit elements adjacent to each other, and the outputs of the several unit elements are read out and the sum thereof is used as the output of that address. The total width of these several unit elements corresponds to the output slit width of the reflected light spectrometer M2. When performing wavelength scanning intermittently with the illumination light spectrometer M1, the wavelength interval is the same as that of the reflected light spectrometer M.
The wavelength width of the output slit S1 of the illumination light spectrometer M1 is wider than the wavelength width corresponding to the output slit width described above in 2. It is set narrower than the wavelength width corresponding to the width. When using a multi-channel photometric element consisting of approximately 500 unit elements, the wavelength range is 10nm from 300nm to 800nm.
Since there are 51 consecutive addresses, the address interval is 10 unit elements, and the number of unit elements constituting the first address is less than 10, and is set to 3 in this embodiment.

Com is a control circuit that performs the following operations. A sample Sm is set in the window w of the integrating sphere I, and wavelength scanning is performed by the illumination light spectrometer M1. When the output wavelength of M1 is λ, the output of the address corresponding to the wavelength λ of the photometric element D is stored in the first memory m1. Further, the outputs at all addresses except for the address corresponding to the wavelength λ are read out on the photometric element and stored in the address corresponding to the wavelength λ of the second memory m2. This operation is performed for each wavelength in the wavelength scanning process of the illumination light spectrometer M1. Further, when a standard white plate is placed on the window w of the integrating sphere I, when the output light wavelength of the illumination light spectrometer M1 is λ, the output of the address corresponding to λ of the photometric element D is stored in the third memory m3. This operation is of course performed for each wavelength in the wavelength scanning process of the illumination light spectrometer M1. If this operation is performed once before sample measurement and the data is stored in the third memory m3, it is not necessary to perform it for each sample unless the light source changes. With the above operation, the first memory m
1 stores the data of H' in FIG. 1, and the second memory m2 stores data on the fluorescence intensity of the fluorescence peak F in FIG.

The control circuit Com then performs the following arithmetic operation.
Read the fluorescence data at the illumination light wavelength λ from the second memory m2, divide it by 3, and then read out the fluorescence data at the illumination light wavelength λ.
It is divided by the data of the address corresponding to the wavelength λ of the memory m3, that is, the intensity of the reflected light of the wavelength λ of the standard white board.
The reason for dividing by 3 is that in this embodiment, three unit elements on the photometric element D constitute one address.
This means taking the average of the outputs of the unit elements, and the reason why the data in the third memory m3 is not divided by 3 is because the standard white plate has no fluorescence, and the wavelength width equivalent to the output slit of the reflected light spectrometer is the same as that of the photometric element D. This is because even if there are three unit elements, the wavelength width of the reflected light is the same as the wavelength width of the output light of the illumination light spectrometer M1, and on the photometric element D, it is well within the width of one unit element. be. Let the above-mentioned division result be A(μ) (μ is the difference between the wavelength of the fluorescent light and the wavelength of the illumination light, and 10 nm is taken as 1). First, perform interpolation calculations. The mountain of fluorescence F in Fig. 1 is approximated by a cubic equation, and we set A(μ) = aμ ³ +bμ ² +cμ+d, where μ is 0 when the wavelength is λ and 1 when 10 nm, so μ is - The value of F (μ) when substituting 2, -1, 1, 2 is 2 points each 10 nm before and after the wavelength λ, λ-2, λ-1, λ+1, λ+2 in Figure 1.
Using the values of A(μ) for a total of four points, A(-2)=-8a+4b-2c+d A(-1)=-a+b-c+d A(+1)=a+b+c+d A(+2)=8a+4b+2c+d from a to d The fluorescence component at wavelength λ, that is, the fluorescence spectral radiance factor Rf(λ), is given by d with μ=0. Note that the interpolation method is not limited to the cubic method described above. Next, the data corresponding to the wavelength λ is read from the first memory m1 and divided by the data corresponding to the wavelength λ in the third memory m3 to obtain the apparent spectral reflection radiance factor Rf(λ). Multiplying and subtracting gives the true spectral reflection radiance factor Rr
(λ) is found. The first step is to multiply d by 3 and subtract it.
The data in the memory is the sum of the true reflection component of the wavelength λ and the fluorescent component spanning three unit elements of the photometric element D, and the above d is the spectral fluorescence radian of one unit element of the photometric element. This is because he is a sphactor.

The above calculation operation is performed for each wavelength point in the wavelength scanning range of the illumination light spectrometer. The data such as the data Rr (λ), Rf (λ) and the relative fluorescence spectral intensity A (μ) for each wavelength obtained in this way are constants unique to the sample, regardless of the characteristics of the illumination light source. A sample in which Rf (λ) is 0 over the entire wavelength range is a sample without fluorescence. Therefore, whether or not the sample has fluorescence can be determined by whether Rf (λ) is 0 or not. Conventionally, the reflective radiance factor and the fluorescent radiance factor were not measured separately, so it was not possible to detect the presence or absence of fluorescent light in the sample. The apparent spectral reflectance of fluorescence accompanying fluorescence differs depending on the wavelength resolution (output slit width) of the reflected light spectrometer. Since the true reflected light has the same wavelength as the incident light, it has a wavelength width determined only by the wavelength resolution of the illumination light spectrometer. However, since fluorescent light is distributed over a wide wavelength range, the slit width in the reflected light spectrometer is widened. As a result, the fluorescence appears to become stronger. The color of a fluorescent object is determined by the sum of the reflected light and the fluorescent light, but if the apparent fluorescent intensity differs depending on the measuring instrument, the three-color stimulus values calculated from it will also differ depending on the measuring instrument. It's coming.

In the above embodiment, the fluorescence radiance factor is determined by first calculating A(μ) and then by interpolation, but the order is reversed and the fluorescence intensity at the illumination light wavelength is first calculated by interpolation, and then the fluorescence intensity is calculated by interpolation. It may be divided by the reflected light intensity at the illumination light wavelength of the standard white board. In addition, the spectral reflection radiance factor is determined by calculating the apparent reflection radiance factor and subtracting the fluorescence radiance factor from it in the above example, but by changing the calculation order, first calculating the spectral reflection radiance factor by calculating the spectral reflection radiance factor from the sample at the illumination light wavelength. It goes without saying that even if the reflected radiance factor is calculated by dividing the value obtained by subtracting the fluorescent light obtained by interpolation by the intensity of the reflected light from the standard white board at the same wavelength, the result will be exactly the same.

According to the present invention, since the resolution of the reflected light spectrometer does not affect the measurement, the output slit of the reflected light spectrometer can be made wider and brighter. Since the fluorescent component is weak, being able to brighten the reflected light spectrometer is advantageous for detecting the effect of fluorescence in fluorescent samples.
When whitening white cloth using fluorescent dye, the yellowing of the white cloth (a slight decrease in the reflectance of the blue-violet light area) is compensated for by the blue-violet fluorescence, so it is effective even with a slight fluorescence intensity. In the present invention, fluorescence can be detected reliably without overestimating the effect of fluorescence.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the general form of the reflected light spectrum of a fluorescent sample, and FIG. 2 is a layout diagram of an optical system and a block diagram of a signal processing section of an apparatus according to an embodiment of the present invention. M1...Illuminating light spectrometer, M2...Reflected light spectrometer, I...Integrating sphere, W...Standard white plate, Sm...Sample, D...Multi-channel photometric element, Com...Control circuit, m1, m2 , m3...Memory.

Claims (1)

[Scope of Claims] 1. An illumination light spectrometer for irradiating a sample with monochromatic light of an arbitrary wavelength; and a multichannel photometric element disposed on a spectral image plane, which is illuminated by the light emitted from the illumination light spectrometer. A reflected light spectrometer that separates the reflected light from the sample, a memory that stores data on the spectral reflected light intensity of a standard white plate, and a multichannel photometric element output of the reflected light spectrometer using the data in the memory. an arithmetic circuit that performs arithmetic processing on the sample illumination light emitted from the illumination light spectrometer; The fluorescence radiance factor of the sample at the sample illumination light wavelength of the sample is calculated by interpolation from the data at the sample illumination light wavelength, and the output of the multichannel photometric element for the sample illumination light wavelength is calculated in the memory for the same wavelength. 1. A color measurement device, characterized in that a calculation is performed to calculate a reflection radiance factor of the sample at the wavelength of the sample illumination light by subtracting the fluorescence radiance factor from the value divided by the data.