JPH10300669A - Equipment for measuring quantity of scattering light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a measurement responsive to high rate variation in the quantity of scattering light while suppressing the effect of optical noise by measuring a specific instantaneous value, the peak value of an electric signal, corresponding to the quantity of scattering light in synchronism with the period of irradiating light. SOLUTION: The equipment for measuring the quantity of scattering light being employed as a range finder, a roughness meter, a chrominance meter or an optical absorption meter comprises a laser diode light source LS for irradiating a light scattering part P1 with a light IL at a quantity of light Q varying at a period T and a frequency f, and a photodiode PD for converting a part of a scattering light S entering through an optical fiber F into a current. Output current from the photodiode PD is passed through a bandpass filter BF of frequency f and amplified to produce a voltage signal Vm and the instantaneous values V1, V2,... at the peak points W1, W2,... of the voltage signal Vm synchronized with the peak points m1, m2,... of the quantity of irradiating light Φ are measured as the quantity of scattering light. The shape at the light scattering part can be observed when an image processor is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the amount of light scattered from a light scattering point.

[0002]

2. Description of the Related Art Conventionally, when measuring the degree of light scattering,
Using DC light as the irradiation light, or irradiating the light scattering portion with the light amount changing at a constant frequency to the light scattering portion, and converting the scattered light amount scattered from here to an electric signal by a photoelectric converter, Filter with a frequency band pass filter, and
The waveform of the electric signal is smoothed to almost DC through a low-pass filter, and then data is sampled and measured.

[0003]

In the conventional scattered light amount measuring apparatus, when DC light is used as the irradiation light, a measurement error due to optical noise is apt to occur, and the irradiation light whose light amount changes at a constant frequency is used. When used, the measurement is smoothed using a low-pass filter having a frequency sufficiently lower than this frequency, so that it is difficult to measure in response to a high-speed change in the amount of scattered light.

The present invention has been made in view of the above circumstances, and provides a scattered light amount measuring apparatus which is hardly affected by external light noise and which can perform measurement in response to a high-speed change in scattered light amount. With the goal.

[0005]

According to the first aspect of the present invention,
When irradiating the light to the light scattering location and measuring the degree of light scattering from this location from the amount of scattered light, irradiate the light scattering location with the light whose light quantity changes at a constant frequency and scatter After converting the scattered light amount into an electric signal by a photoelectric converter, the scattered light amount is filtered by a band-pass filter having the above-mentioned frequency, and the peak value of the electric signal is specified in a cycle synchronized with the cycle of the irradiation light. The instantaneous value is measured to measure the amount of scattered light.

The above-mentioned electric signal is assumed to exhibit a degree of light scattering, that is, a substitute characteristic of the amount of scattered light.

In the present invention, since the electric signal is filtered in a specific frequency band, the electric signal is hardly affected by external noises other than this frequency, and has a longer time constant than the period of measuring the instantaneous value. The electric signal is not smoothed using a low-pass filter, but a unique instantaneous value such as a peak value of the electric signal is measured in synchronization with the cycle of the irradiation light amount. Measurement that responds to high-speed changes in

The invention according to claim 2 is characterized in that the distance measuring device is set as a distance measuring device in which a distance between a light scattering portion and a portion where the amount of scattered light is measured is related.

In the present invention, the relationship that the amount of scattered light decreases as the distance from the portion where light is scattered is reduced, is utilized.
The distance from the scattered light amount to the position where the light is scattered and the position where the scattered light amount is measured is measured.

The invention according to claim 3 is characterized in that the roughness is set as a roughness meter in which the roughness of a portion where light is scattered and the amount of scattered light are related.

The present invention utilizes the fact that the amount of scattered light varies depending on the roughness of the portion where light is scattered, and the roughness of the portion where light is scattered is measured from the amount of scattered light.

The invention according to claim 4 is characterized in that it is set as a color difference meter in which the color or shade of light at which light is scattered and the amount of scattered light are related.

The present invention utilizes the fact that the amount of scattered light varies depending on the color or the color density of the light scattering portion, and the color difference or color density of the light scattering portion is measured from the scattered light amount.

The invention according to claim 5 is characterized in that it is set as a light absorptivity meter in which the light absorptance of a portion where light is scattered and the amount of scattered light are related.

The present invention utilizes the fact that the amount of scattered light differs depending on the difference in the light absorptance of the portion where light is scattered, and the light absorptance of the portion where light is scattered is measured from the amount of scattered light.

According to a sixth aspect of the present invention, there is provided an image processing apparatus capable of simultaneously taking in image data of a light scattering portion.

According to the present invention, since the image processing apparatus including the optical fiber and the CCD camera is provided, the scattered light amount and the image data can be taken together.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of a scattered light amount measuring apparatus according to the present invention. When the irradiation light IL of the irradiation light amount Φ changing with the period T and the frequency f with the elapsed time t from the laser diode light source LS is applied to the light scattering portion P1, a part of the scattered light S becomes the scattered light amount. The light is incident on the end face P2 of the optical fiber F at the position of the distance l by φ and is condensed on the photodiode PD and converted into a current. An extra frequency signal mixed into this current is removed by a band-pass filter BF of frequency f, and then amplified by an amplifier AP to become a voltage signal Vm. In the figure,
Peak points W1, W2,... Wn of the voltage signal Vm
Is synchronized with the peak positions m1, m2,... Mn of the irradiation light amount Φ, and the instantaneous value n of the irradiation light amount Φ
The instantaneous values v1, v2,... Vn of the voltage signal Vm are measured at the same cycle T as the cycle T of 1, n2,. Therefore, these instantaneous values indicate the degree of light scattering, and the measurable speed is increased to the frequency f of the irradiation light source.

In the above example, the instantaneous value is measured by continuous sampling of the cycle T without passing the low-pass filter through the voltage signal Vm. However, the sampling cycle may be 3T or the sampling cycle may be T. When the measurement is performed through a low-pass filter having a time constant of 3T or a time shorter than T, where T / 5 is the cycle of the irradiation light, harmonic noise superimposed on the voltage signal Vm is removed, and
Data is obtained with a period of 3T, T for a change in the amount of scattered light.

In the figure, an oscillator OC, a modulator MD, a power supply PW, a color filter Q, a lens L, a light scattering surface P0, a current / voltage converter I / V, and an output device O are provided. A CPU, an A / D / D / A converter, a display and the like are provided according to the output function.

FIG. 2 shows an embodiment of a conventional scattered light amount measuring apparatus, in which a voltage signal Vm based on the scattered light amount is shown.
Is smoothed by a low-pass filter LF having a circuit time constant sufficiently longer than the period T. For example, when the amount of scattered light changes in a shorter time than the period T, measurement can be performed in response to this. difficult.

FIG. 3 relates to claim 2 in which the distance ln and the instantaneous value vn of the voltage signal depending on the amount of scattered light incident from the fiber end face P2 are recorded in the output device O in advance by correlating them with a calibration curve. In this case, the distance ln is immediately calculated from the measured value of the instantaneous value vn of the voltage signal by a computer or the like in the output device.
A range finder capable of measuring the distance is provided.

Compared with a distance meter that measures the distance by reading the light irradiation position with a CCD or PSD, the size is extremely small because an optical fiber is used in the optical path. It can be used in harsh environments such as conditions and toxic atmospheres.

Further, a laser diode operating at a high frequency
The use of a PIN and a photodiode allows high-frequency modulation of the amount of irradiated light, so that it can be used in an extremely high-speed measurement and in an environment where the illuminance varies extremely.

F ₁ and F ₂ are part of an optical monitor, each of which serves as a light taking-in port.

FIG. 4 shows a third embodiment of the present invention, in which the roughness measurement object is moved in the direction of the arrow while maintaining the distance l between the light scattering portion P1 and the end face P2 of the optical fiber F constant. R ₁ and R ₂ are to be measured.

That is, the roughness Rn of the object to be measured and the instantaneous value vn of the voltage signal due to the amount of scattered light incident from the fiber end face P2 are previously associated with a calibration curve, and the instantaneous value vn of the voltage signal is measured. This is a roughness meter for measuring the roughness Rn.

FIG. 5 relates to claim 4, in which the object having different colors or different shades is moved in the direction of the arrow while keeping the distance l between the light scattering portion P1 and the end face P2 of the optical fiber F constant. The color C
The difference between 1 and C2 or the color shades D1 and D2 are measured.

That is, the color value Cn or the color density Dn of the object to be measured and the instantaneous value vn of the voltage signal due to the amount of scattered light incident from the fiber end face P2 are previously associated with a calibration curve, and the instantaneous value vn of the voltage signal is calculated. This is a color difference meter that measures color Cn or color density Dn.

FIG. 6 relates to claim 5, wherein a measured object having a different light absorptivity is moved in the direction of the arrow while keeping the distance l between the light scattering portion P1 and the end face P2 of the optical fiber F constant. Since the scattering amount differs depending on the light absorption rate and the light absorption rate, the light absorption rates E ₁ and E ₂ are measured.

That is, the instantaneous value vn of the voltage signal is measured by associating the light absorption rate En of the object to be measured with the instantaneous value vn of the voltage signal due to the amount of scattered light incident from the fiber end face P2 by a calibration curve in advance. This is a light absorption rate meter for measuring the light absorption rate En.

FIG. 7 relates to claim 6, wherein the light incident from the fiber end face P2 is split into two fibers, one of which is the scattered light amount measurement according to claim 1, 2, 3, 4 or 5. The other is provided with an image processing device G capable of taking in image data of a light scattering portion, so that the form of the light scattering portion can be observed while measuring the amount of scattered light.

In the embodiments of the present invention, the configuration of the optical system has mainly been described for the optical fiber. However, the present invention is not limited to this, and optical components such as lenses and mirrors may be used alone or in combination according to the object to be measured. It can be used as appropriate. Also, the light source has been described using laser light as an example. However, the present invention is not limited to this, and LED light sources, white light sources, or
It is also possible to use a combination of two or more monochromatic light sources.

In each of the embodiments described above, the scattered light amount measuring apparatus and its application system corresponding to each purpose have been described. However, the present invention is not limited to these examples, and the above-described scattered light amount measuring apparatuses may be appropriately used. The scattered light amount measuring device may be given a predetermined relationship by a combination and control means.

[0035]

According to the present invention, the degree of light scattering is measured by measuring a specific instantaneous value such as a peak value of an electric signal corresponding to the amount of scattered light in a cycle synchronized with the cycle of irradiation light. Therefore, a high-speed, accurate, and small-sized scattered light amount measuring apparatus and its application system are constructed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a scattered light amount measuring apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an embodiment of a conventional scattered light amount measuring device.

FIG. 3 is an explanatory diagram of a case where the present invention is applied to a range finder in the embodiment.

FIG. 4 is an explanatory diagram of a case where the present invention is applied to a roughness meter in an embodiment.

FIG. 5 is an explanatory diagram when applied to a color difference meter in the embodiment of the present invention.

FIG. 6 is an explanatory diagram of a case where the present invention is applied to a light absorptometer in an embodiment.

FIG. 7 is an explanatory diagram in a case where an image processing apparatus is provided in the embodiment of the present invention.

[Explanation of symbols]

LS laser diode light source T period f frequency t elapsed time Φ irradiation light amount IL irradiation light P1 light scattering point S scattered light φ scattered light amount 1, ln distance F, F ₁ , ₂ optical fiber P2 end face PD photo diode BF Band pass filter AP amplifier Vm Voltage signal W1 to Wm Peak position of voltage signal m1 to mn Peak position of irradiation light amount n1 to nn Instantaneous value of irradiation light amount v1 to vn Instantaneous value of voltage signal OC oscillator MD modulator PW power Q color filter L lens PO light scattering surface I / V voltage converter O output device LF Russia - pass filter Rn, R _{1, 2} roughness Cn, C _{1, 2-color} Dn, D _{1, 2-color} density En, E _{1, 2} optical absorptance G image processing apparatus

Claims (6)

[Claims] When irradiating light to a light scattering location and measuring the degree of light scattering from this location from the amount of scattered light, irradiation light whose light quantity changes at a constant frequency is applied to the light scattering location. After converting the amount of scattered light scattered from this portion into an electric signal by a photoelectric converter, the scattered light amount is filtered by a band-pass filter of the above-mentioned frequency, and the electric signal is pipied at a period synchronized with the period of irradiation light. The characteristic is that a specific instantaneous value such as a peak value is measured to measure the amount of scattered light. 2. The scattered light amount measuring apparatus according to claim 1, wherein the distance between the light scattering part and the scattered light amount measuring part is set as a distance meter. 3. The scattered light amount measuring device according to claim 1, wherein the scattered light amount measuring device is set as a roughness meter that associates the roughness of the light scattering portion with the scattered light amount. 4. The scattered light amount measuring device according to claim 1, wherein the scattered light amount measurement device is set as a color difference meter that associates the scattered light amount with the color or color shading of the light scattering portion. 5. The scattered light amount measuring device according to claim 1, wherein the scattered light amount measuring device is set as a light absorptance meter that associates the light absorptance of a portion where light is scattered with the scattered light amount. 6. The scattered light amount measuring device according to claim 1, further comprising an image processing device capable of taking in image data of a light scattering portion.