JPH0776710B2 - Spherical Luminometer Spectral Response Measurement Method - Google Patents

Description

TECHNICAL FIELD The present invention relates to the measurement of characteristics of a spherical photometer, which is widely used in the field of optical emission measurement.

2. Description of the Related Art Spherical luminometers are widely used in the field of optical emission measurement as a device for measuring the total luminous flux of a light source or as a device for measuring the reflectance and transmittance of materials.

In these applications, the relative spectral responsivity of the spherical photometer is an important characteristic that determines the correction coefficient of the device output, and has a great influence on the measurement accuracy of the spherical photometer. The relative spectral responsivity of the spherical photometer is mainly determined by the spectral efficiency of the integrating sphere used in the spherical photometer and the relative spectral responsivity of the light receiver including the light receiving window. That is, R (λ) = k ₁ · Q (λ) · D (λ) (5) where R (λ) is the relative spectral responsivity of the spherical photometer, k ₁ is a constant, and Q (λ) Is the spectral efficiency of the integrating sphere, and D (λ) is the relative spectral responsivity of the light receiver including the light receiving window. Q (λ) is
Let S be the internal area of the inner wall surface of the integrating sphere, ρ (λ) be the spectral reflectance, and let s be the area of the light-absorbing object in the integrating sphere and ρ ′ (λ) be the spectral reflectance, Q (λ) = k ₂・ Ρ (λ) / {1- (1-α) ・ ρ (λ) -ρ '(λ)} (6) (k ₂ is a constant, α = s / S) Optics [AP
PLIED OPTICS], Vol.6, No.4, 757, 1967). Therefore,
From equations (5) and (6), the relative spectral responsivity R of the spherical photometer
(Λ) is obtained from Q (λ) and D (λ).

Problems to be Solved by the Invention A light receiver used in a spherical photometer is configured by combining a light receiving element such as a silicon photodiode or a photomultiplier tube with an optical filter. The optical transmittance of the optical filter should be such that the light receiver has a desired spectral responsivity D (λ) (spectral luminous efficiency in the case of a spherical light flux meter) when combined with a light receiving element. . It is known that the characteristics of the spectral transmittance of the optical filter greatly change depending on the light entering / exiting condition (angle of entering / exiting). Therefore, the spectral responsivity D (λ) of the light receiver varies depending on the light input / output conditions. In the conventional measurement of D (λ), D
Conditions for light incident on the receiver (normally normal incidence) in the device for measuring (λ) and conditions for incident light on the receiver when attached to a spherical photometer (hemispherical diffuse incidence) However, due to the above reason, the measurement error of D (λ) was large. Also, to measure the relative spectral responsivity,
Separately, a dedicated measuring device was required, and the measurement was not easy.

Means for Solving the Problem A spherical equation can be easily and accurately solved by forming a simultaneous equation from the relationship between the spectral distribution of diffused light generated in a spherical luminous flux meter and the output of the receiver, and solving this simultaneous equation. The relative spectral responsivity of the meter can be obtained, and the above problem can be solved.

Function The constant wavelength region C is divided into n (n> 1) small regions having a constant wavelength width, and the relative spectral responsivity of each small region j (j = 1, ..., N) is R _j . The spectral distribution P _ij (i
= 1, ..., n, j = 1, ..., n) When the light is sequentially given, the photodetector output is the spectral efficiency of the integrating sphere used in the spherical photometer, Q _j , and the spherical light flux. The spectral responsivity including the window of the receiver used in the meter
D _j (K is a constant, i = 1, ..., N, j = 1, ..., N), and an n-element simultaneous linear equation having D _j as an unknown is obtained. By solving this, D _j can be obtained.

Further, the spherical photometer spectral responsivity R _j can be obtained from the equation R _j = Q _j · D _j (3).

Further, by substituting the relationship of the expression (3) into the expression (1), (K is a constant, i = 1, ..., N, j = 1, ..., N) Simultaneous equations are obtained, and R _j can be obtained without needing to obtain Q _j .

In addition, light having a spectral distribution P _j was given to the spherical photometer to change the spectral efficiency Q _ij of the integrating sphere n times (i = 1, ..., N, j = 1,
......, n), the spherical spectrophotometer spectral responsivity can be similarly obtained.

Example An example of the present invention will be described with reference to mathematical formulas and drawings.

As a first embodiment of the present invention, FIG. 1 shows a principle diagram of a spherical photometer spectral responsivity measuring method using a light color variable light source as a means for changing the spectral distribution of light in the spherical photometer. First
In the figure, 1 is an integrating sphere, 2 is a light receiver, 3 is a light color variable light source, 4 is a light color variable control device, 5 is a computing device, and 6 is a light shielding plate. It is assumed that the spectral efficiency Q _j (j = 1, ..., N) of the integrating sphere 1 is known. The relative spectral responsivity of the light receiver 2 is D _j (j = 1,
..., n), and assume that it is an unknown number. The light shielding plate 6 is placed in a place where the light of the variable color light source 3 is not directly applied to the light receiver 2. The light color variable control device 4 turns on the light color variable light source 3, and light with a spectral distribution P _j (j = 1, ..., N) is generated in the integrating sphere. is light diffused incident by sphere 1, as a _{result, I = k · P j ·} Q j · D j ...... (7) (k is a constant, j = 1, ......, n) consists of the light receiver 2 The output I is obtained. If P _j is obtained in advance, if the above operation is repeated for several times in the wavelength band of the desired spectral responsivity, then from equation (7), (K is a constant, i = 1, ..., N, j = 1, ..., N) An n-element simultaneous equation can be created. Responsiveness D _j
(J = 1, ..., n) can be obtained. From this _{D j, R j = k 1} · Q j · D j ...... (8) (k 1 is a constant, j = 1, ......, n ) consists of a spherical photometer with relationship relative spectral response of R _j (J = 1,
..., n) can be obtained by the arithmetic unit 5.

At least one of the spectral distributions of n kinds of light emitted from the variable light color light source is included in the wavelength of the spectral responsivity of the light receiver to be measured.

By considering the spectral efficiency of the integrating sphere and the spectral response of the light receiver, (K is a constant, i = 1, ..., n, j = 1, ..., n) From the n-element simultaneous equations, spherical spectrophotometer spectral response R _j (j
= 1, ..., n) can be directly obtained.

As shown in FIG. 2, the light color variable light source can be measured even by a spherical beam meter having a small diameter by having a structure in which light is incident from the opening of the integrating sphere.

As shown in FIG. 3, if the light from the variable color light source is applied only to the inner wall surface of the integrating sphere, the spectral responsivity of a spherical flux meter composed of an integrating sphere without a light shielding plate can be measured. can do.

A color CRT may be used as the light color variable light source.

As a second embodiment of the present invention, FIG. 4 shows a principle diagram of a spherical photometer spectral responsivity measuring method using a light absorbing sheet as a means for changing the spectral distribution of light in the spherical photometer. Fourth
In the figure, 1 is an integrating sphere, 2 is a light receiver, 8 is a light source, 5 is an arithmetic unit, 6 and 7 are light shielding plates, and 9 is a light absorbing sheet. The relative spectral responsivity of the light receiver 2 is D _j (j = 1, ..., n)
Then, let us assume that it is an unknown number. It is assumed that the spectral distribution of the light source 8 is known. The light shielding plate 6 is placed in a place where the light from the light source 8 is not directly applied to the light receiver 2. The light shielding plate 7 is placed in a place where the light of the light source 8 does not directly hit the light absorbing sheet 9. It is assumed that the inner area S of the integrating sphere 1 and the spectral reflectance ρ _j (j = 1, ..., N) of the inner wall surface are known.

The area of the light absorbing sheet 9 is s, and the spectral reflectance is ρ ′ _j (j =
1, ……, n). In the integrating sphere 1, the light emitted from the light source 8 is reflected by the inner wall surface of the integrating sphere 1 and the light absorbing sheet 9 and enters the photodetector 2.
Is output. At this time, the integrating sphere 1 spectral efficiency Q _j (j = 1,
..., n) is expressed by the following equation.

(K ₂ is a constant, α = s / S, j = 1, ..., n) Therefore, the output I of the photodetector 2 is (K is a constant, j = 1, ..., N). Number of wavelength bands of desired spectral responsivity, ie, n
The spectral reflectance ρ ′ _j (j = 1, j = 1,
..., n) and the area s are changed and the above operation is repeated, (K is a constant, i = 1, ..., N, j = 1, ..., N) An n-element simultaneous linear equation can be created. spectral responsivity _{D j (j = 1, ......} , n) can be obtained, as in the first embodiment, sphere photometer relative spectral response of R _j (j = 1,
..., n) can be obtained by the arithmetic unit 5.

In addition, as the light absorption sheet, a material including at least one spectral reflectance at a wavelength in the spherical luminous flux spectral responsivity is selected.

If the light absorption sheet has a spectral reflection characteristic that is not constant in the wavelength band of the spectral responsivity of the spherical photometer, only the area of the light absorption sheet may be changed as many times as necessary to solve the simultaneous equations.

As shown in FIG. 5, by providing a light absorbing sheet switching device at the opening of the spherical photometer, the present method can be used even for a spherical photometer with a small diameter, and a quick measurement can be performed. You can In FIG. 5, 10 is a light absorbing sheet switching device.

FIG. 6 shows the principle of a method of using a polarizing element as a means for changing the spectral distribution of light in a spherical photometer as the third embodiment of the present invention. In FIG. 3, 1 is an integrating sphere,
Reference numeral 11 is a polarizing element, 12 is a polarizing plate, 13 is a reflecting plate, and 14 is a polarizing element control device. In FIG. 6, the light incident from the polarizing plate 11 becomes linearly polarized light, passes through the polarizing element 11, and is reflected by the reflecting plate.
The light is reflected by 13, is transmitted through the polarizing element 13 again, and is emitted from the polarizing plate. At this time, the emitted light is determined by the polarization plane of the polarizing plate 11 and the degree of polarization by the polarization element 12 in the round-trip optical path. It is known that the degree of this polarization depends on the speed of light in the polarizing element 12, that is, the wavelength of the light. Therefore, by the polarizing element 14,
By changing the polarization state of the polarizing element 12, the wavelength component of the light emitted from the polarizing plate 11, that is, the polarizing plate 11, the polarizing element 12,
The apparent spectral reflectance including the reflection plate 13 can be changed. This has the same effect as changing the light absorbing sheet in the second embodiment of the present invention,
Similar to the method shown in the second embodiment of the present invention, the spherical photometer spectral responsivity can be obtained.

The reflector 13 can be omitted.

A liquid crystal element can be used as the polarizing element.

As a fourth embodiment of the present invention, FIG. 7 shows a principle diagram of a spherical luminous flux spectroscopic responsivity measurement using a light bulb and a light bulb lighting device as a light color variable light source and a light bulb lighting voltage variable device as a light color variable control device. Show. In FIG. 7, 1 is an integrating sphere, 2 is a light receiver, 5 is a computing device, 15 is a light bulb, 16 is a light bulb lighting device,
Reference numeral 17 is a light bulb lighting voltage varying device. In FIG. 7, the light bulb lighting device 15 lights the light bulb 14, and light is supplied into the integrating sphere 1. Light bulb lighting voltage variable device 17,
14 lighting voltage is variable. The spectral distribution of light emitted from a light bulb depends on the temperature of the light bulb distribution, that is, the filament temperature of the light bulb. Also, the filament temperature of the light bulb is
By depending on the lighting voltage of the light bulb, the spectral distribution of the emitted light of the light bulb depends on the lighting voltage. Therefore, by changing the lighting voltage of the light bulb 14 by the light bulb lighting voltage varying device 17, the spectral distribution of the emitted light of the light bulb 14 can be changed. In this way, the integrating sphere 1
Since the spectral distribution of the light in the inside can be changed, the spherical photometer spectral responsivity can be obtained as in the first embodiment of the present invention.

As described above, the spherical photometer spectral responsivity can be obtained by the apparatus configuration and procedure described in each of the above embodiments, and the present invention can be implemented.

EFFECTS OF THE INVENTION The present invention can easily and accurately measure the spectral responsivity of a spherical photometer.

Also, the present invention does not require an optical receiver spectral responsivity measuring device, sophisticated spectral responsivity measuring techniques, or highly accurate spectral responsivity standards.

In addition, when measuring the spectral response of a spherical photometer by this method, the incident conditions of the light receiver can be the same as in the actual configuration of the spherical photometer, and therefore the accuracy of the measured values is extremely high. .

As described above, the present invention realizes a method for easily and highly accurately measuring the spectroscopic responsivity of a spherical photometer, and uses a correction coefficient calculated from the spectroscopic responsivity of a spherical photometer obtained by this method. The accuracy of measurement can be improved by correcting the measured value by using the method, and its practicality is extremely high.

[Brief description of drawings]

1, 2 and 3 are measurement principle diagrams of the first embodiment of the present invention, FIGS. 4 and 5 are measurement principle diagrams of the second embodiment of the present invention, and FIG. FIG. 7 is a measurement principle diagram of the third embodiment of the present invention, and FIG. 7 is a measurement principle diagram of the fourth embodiment of the present invention. 1 ... Integrating sphere, 2 ... Receiver, 3 ... Light color variable light source, 4
...... Light color variable control device, 5 ...... Calculation device, 6 ・ 7 ...... Light shielding plate, 8 ...... Light source, 9 ...... Light absorbing sheet, 10 ...... Light absorbing sheet switching device, 11 ...... Polarizing plate, 12 ...... Polarizing element,
13 …… Reflector, 14 …… Polarizer control device, 15 …… Light bulb,
16 …… Light bulb lighting device, 17 …… Light bulb lighting voltage variable device.

Claims (8)

[Claims] 1. A constant wavelength region C is divided into n (n> 1) small regions having a constant wavelength width, and each small region j (j = 1, ...
, N) and the relative spectral responsivity with sensitivity in the wavelength region C is D _j with the integrating sphere having a spectral efficiency of Q _j (j = 1, ..., n).
(J = 1, ..., n) In a spherical fluxmeter composed of a light receiver, P _ij (i = 1, ..., n) is provided by a light supply means that prevents the light from hitting the light receiver. , J = 1, ..., n)
The light with n different spectral distributions is sequentially entered into the spherical photometer,
Output of the photodetector that is generated or made incident and is sequentially output
It is characterized in that the spectral responsivity D _j (j = 1, ..., N) of the photodetector is obtained based on the n-element simultaneous equation (1) established from I _i (i = 1, ..., N). , Spherical Luminometer Spectral response measurement method. (K is a constant, i = 1, ..., n, j = 1, ..., n) 2. A constant wavelength region C is divided into n (n> 1) small regions having a constant wavelength width, and each wavelength region C has sensitivity, and each small region j (j = 1 ,. , n) in a spherical fluxmeter composed of a photoreceiver having a relative spectral responsivity of D _j (j = 1, ..., N) and an integrating sphere, such that light receiving means prevents direct light from hitting the photoreceiver. Light having a spectral distribution of P _j (i = 1, ..., N) is generated or made incident into the spherical photometer, and the spectral efficiency Q _ij (i = 1, ..., N, j) of the integrating sphere is generated. = 1,
, N) is changed in n ways, and the spectral response of the photoreceiver is based on the n-element simultaneous equation (2) established from the photoreceiver output I _i (i = 1, ..., n) that is sequentially output. Degree D _j (j = 1, ...
..., n) Spherical Luminometer Spectral Responsiveness Measuring Method. (K is a constant, i = 1, ..., n, j = 1, ..., n) 3. The spherical photometer spectroscopic responsivity measuring method according to claim 1, wherein the simultaneous equation (4) obtained by substituting the formula (3) into the formula (1) is solved. A spherical photometer spectroscopic responsivity measuring method characterized by obtaining responsivity R _j . R _j = Q _j · D _j …… (3) (K is a constant, i = 1, ..., n, j = 1, ..., n) 4. The spherical photometer spectroscopic responsivity measuring method according to claim 2, wherein a light source is used as the light supplying means, and the area and the spectral reflectance are known as means for changing the spectral efficiency Q _ij of the spherical photometer. The method for measuring the spectral responsivity of a spherical photometer, characterized in that the light absorbing sheet is placed on the inner wall surface of the spherical photometer so as not to be exposed to the direct light of the light source. 5. The spherical luminous flux spectroscopic responsivity measuring method according to claim 2, wherein a light source is used as the light supply means, and the area is known as means for changing the spectral efficiency Q _ij of the spherical luminous flux meter. And a polarizing plate, a reflecting plate, and a polarizing element driving device are used. 6. The spherical luminous flux spectroscopic responsivity measuring method according to claim 1, wherein a light bulb and a light bulb lighting device are used as the light supply means, and the light bulb lighting voltage is varied as a means for changing the spectral distribution P _ij of the light. A spherical photometer spectral responsivity measuring method characterized by using an apparatus. 7. The spherical photometer spectral responsivity measuring method according to claim 1 or 3, wherein a CRT is used as a light supplying means,
A spherical photometer spectral responsivity measuring method characterized in that a CRT controller is used as a means for changing the spectral distribution P _ij of light. 8. The spherical photometer spectral responsivity measuring method according to claim 5, wherein a liquid crystal element is used as the polarizing element.