JP2021173602A - Particle visualization system and particle visualization method - Google Patents

Abstract

To provide a particle visualization system and a particle visualization method, with which it is possible to visualize particles under an environment of being irradiated by illumination means.SOLUTION: The above problem is solved by a particle visualization system and a particle visualization method, the particle visualization system being used in an environment of being irradiated with light by illumination means 53 and comprising: irradiation region forming means for forming, in said environment, an irradiation region 54 by light irradiation from a light source 20; an optical filter 52 for passing a portion of light through, as transmitted light, which includes scattering light 51 emanated by particles floating in the irradiation region 54 upon light irradiation from the light source 20 and attenuating the rest of light; and imaging visualization means 15 for imaging the scattering light 51 of the transmitted light and visualizing the particles. The scattering light 51 has a peak A in a wavelength spectrum of the scattering light 51, and the illumination means 53 has a peak B, the full width at half maximum of which is 50 nm or less, in a wavelength spectrum of the illumination means 53, the full width at half maximum of the optical filter 52 being 10 nm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a particle visualization system and a particle visualization method.

Conventionally, when visualizing particles floating in space or liquid, the particles are visualized by irradiating the particles with a laser beam or the like from a light source to generate scattered light and imaging the scattered light (for example,). There is a technology to detect). Patent Document 1 discloses a technique for detecting smoke in an environment where the influence of ambient light is small. Specifically, smoke is detected using ambient light, particularly a light source in a wavelength band outside the spectrum of sunlight.

One of the reasons for using a light source in a wavelength band outside the spectrum of ambient light is as follows. If a light source having a specific wavelength in the wavelength band of the spectrum of ambient light is used, the wavelength of the generated scattered light is also included in the wavelength band. It will be imaged. Then, it becomes difficult to visualize the particles with good contrast. Therefore, in order to clearly visualize the particles, it is necessary to take an image in a wavelength band avoiding ambient light. In this method, as the light source for generating scattered light, a wavelength on the short wavelength side, which is less affected by sunlight, is used, so that the selection range of the light source to be used is limited.

Japanese Patent Application Laid-Open No. 2011-503581

Mikini Takahashi, "Basic Aerosol Engineering," Yokendo, 1982, pp. 146-150

On the other hand, in the field of manufacturing products such as electronic devices, there is a need to visualize particles suspended in the environment. During manufacturing operations, particles floating in the environment may adhere to product materials or intermediates, causing problems with the product. Therefore, it is useful to visualize the particles suspended in this environment to understand how much the particles are suspended. However, for the purpose of visualizing particles, performing manufacturing work in an environment where the influence of irradiation by ambient light, for example, lighting means such as a lighting fixture is small, induces work mistakes of workers in the work environment. There is a risk and it lacks safety.

Therefore, it is an object to visualize particles in an environment irradiated by lighting means, and the following aspect solves this problem.
<First aspect>
It is a particle visualization system used in an environment illuminated by lighting means.
Irradiation area forming means for forming an irradiation area by light irradiation from a light source in the environment, and
An optical filter that receives light irradiation from the light source, transmits scattered light emitted by particles floating in the irradiation region, transmits a part of the light to be transmitted light, and attenuates the rest.
It is provided with an imaging visualization means for imaging the scattered light of the transmitted light and visualizing the particles.
The scattered light has a peak A in the wavelength spectrum of the scattered light.
The illuminating means has a peak B having a full width at half maximum of 50 nm or less in the wavelength spectrum of the illuminating means.
The optical filter is
The full width at half maximum is 10 nm or less,
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of the peak B.
The wavelength of the peak A is within the wavelength band of the full width at half maximum of the optical filter.
A particle visualization system characterized by this.

It is a particle visualization method performed in an environment illuminated by lighting means.
An irradiation region forming step of forming an irradiation region by irradiating light from a light source in the environment, and
The optical filter has an optical filter that transmits a part of the light including scattered light emitted by particles floating in the irradiation region to be transmitted light and attenuates the rest by receiving the light irradiation from the light source. The spectroscopic step of obtaining the transmitted light and
It is provided with an imaging visualization step of imaging the scattered light of the transmitted light and visualizing the particles.
The scattered light has a peak A in the wavelength spectrum of the scattered light.
The illuminating means has a peak B having a full width at half maximum of 50 nm or less in the wavelength spectrum of the illuminating means.
The optical filter is
The full width at half maximum is 10 nm or less,
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of the peak B.
The wavelength of the peak A is within the wavelength band of the full width at half maximum of the optical filter.
A particle visualization method characterized by this.

Since the irradiation area is formed by the light irradiation from the light source in the environment irradiated by the lighting means, the irradiation area is composed of two types of light, the light by the lighting means and the light by the light source. Floating particles can be visualized by dispersing the light in the irradiation region with an optical filter and imaging the scattered light among the transmitted light transmitted through the optical filter.

Of the wavelength spectrum in the illumination means, the light in the wavelength band that does not pass through the optical filter is not imaged, and the light in the wavelength band that passes through the optical filter is imaged.

Since a bandpass filter having a relatively narrow width is used, the amount of light transmitted through the optical filter can be suppressed. Further, if the light transmittance of the optical filter is the above-mentioned condition, the light transmittance of the light of the illumination means is lower than the light transmittance of the peak A, so that the amount of light of the illumination means transmitted through the optical filter is relatively large. The amount of scattered light is small, and the scattered light is imaged with good contrast, and the particles can be clearly visualized.

Since the peak A of the wavelength spectrum in the scattered light is within the wavelength band of the half-value full width of the optical filter, the optical filter transmits the scattered light well, and the imaging of the scattered light becomes more conspicuous.

<Second aspect>
The particles are dust,
The particle visualization system of the first aspect.

Since the particle size d of the dust generally satisfies α ≧ 2, the scattered light intensity does not significantly depend on the wavelength of the light source. Therefore, the particles can be visualized without being significantly affected by the wavelength of the light source. Since the limitation by the light source wavelength is suppressed, the particles can be visualized by using a light source that emits light having a long wavelength regardless of the short wavelength. Regarding α, α = πd / λ, d: particle size, λ: wavelength, which will be described later.

<Third aspect>
The optical filter blocks light having a wavelength of the peak B.
The particle visualization system of the first aspect.

Since the light having the wavelength of peak B is blocked by the optical filter, the influence of the lighting means can be further suppressed. Here, when the optical filter blocks light, it is assumed that the light transmittance of the light in the optical filter is less than 1% (including 0%).

<Fourth aspect>
The peak B is a group of peaks B composed of a plurality of peaks B.
The optical filter is
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of any one peak in the peak B group.
The particle visualization system of the first aspect.

Even if the illuminating means has a wavelength spectrum of peak B group, under the above-mentioned conditions, the light transmittance of the light radiated by the illuminating means is low, so that the amount of light of the illuminating means transmitted through the optical filter is relative. It is possible to image the scattered light with good contrast and clearly visualize the particles.

<Fifth aspect>
The lighting means is a fluorescent lamp or a metal halide lamp.
The particle visualization system of the first aspect.

Since the wavelength spectrum of a fluorescent lamp or metal halide lamp has a steep peak curve and a small relative intensity in a wavelength band other than the peak curve, the influence of the fluorescent lamp or metal halide lamp can be suppressed, and scattered light is imaged with better contrast. can do.

According to the present invention, particles can be visualized in an environment illuminated by lighting means.

It is explanatory drawing of the particle visualization system. It is explanatory drawing which shows the example of the irradiation area forming means. It is explanatory drawing which shows another example of an irradiation area forming means. It is explanatory drawing which shows another example of an irradiation area forming means. It is a figure which shows the relationship between the wavelength band and light transmittance in an optical filter. It is a figure which shows the relationship between the wavelength band and light transmittance in an optical filter. It is a figure which shows the relationship between the peak of the wavelength spectrum of an optical filter and scattered light, and the peak of the wavelength spectrum of an illuminating means. It is a figure which shows the relationship between the peak of the wavelength spectrum of an optical filter and scattered light, and the peak of the wavelength spectrum of an illuminating means. It is a figure which shows the wavelength spectrum of a fluorescent lamp. It is a figure which shows the wavelength spectrum of the metal halide lamp. It is a figure which shows the wavelength spectrum of an incandescent lamp. It is a relational diagram of α and i ₁ + i _2. It is a figure which shows the captured image. It is a figure which shows the captured image. It is a figure which shows the captured image. It is a figure which shows the captured image. It is a figure which shows the captured image. It is a figure which shows the captured image. It is explanatory drawing of the peak curve. It is explanatory drawing which shows another example of an irradiation area forming means. It is a figure which shows the relationship between the full width at half maximum of an optical filter, and the brightness value of a background area. It is a figure which shows the distribution of the scattered light intensity of a particle. It is a figure which shows the distribution of the scattered light intensity of another particle. It is explanatory drawing which shows an example of the condensing irradiation area.

Hereinafter, embodiments for carrying out the present invention will be described in detail. The following description and drawings merely show one embodiment of the present invention.

The particle visualization system according to the present embodiment is used in an environment irradiated by the illumination means 53, and the irradiation region forming means for forming the irradiation region 54 by light irradiation from the light source 20 in the environment and the irradiation region forming means from the light source 20. An optical filter 52 that transmits a part of the light containing the scattered light 51 emitted by particles floating in the irradiation region 54 to be transmitted light and attenuates the rest, and the scattered light of the transmitted light. It is provided with an imaging visualization means 15 that images the 51 and visualizes the particles. The term "particle visualization" as used herein means that fine particles that cannot be recognized as they are are represented as visual information that can be recognized by humans by using the particle visualization system or the particle visualization method of this embodiment. say.

Prior to explaining each means, the relationship between particles and scattered light will be described. The particles existing in the irradiation region formed at the wavelength λ scatter the scattered light of the wavelength. The scattered light intensity I (θ, λ) at this time is generally expressed by the following equation (1) (Basic Aerosol Engineering, by Mikini Takahashi, edited by Yokendo, 1982, p.147, equation (7.7)). reference).

Here, for each parameter,
_{I (θ, λ): Scattered light intensity λ = λ 0} / μ _{1 at} the scattering angle θ when one particle is incident with natural light of unpolarized wavelength λ of unit intensity.
m = μ ₂ / μ ₁
α = πd / λ
β = mα
ω = 2π / λ (angular frequency)
R: Distance from the particle (however, R >> d)
λ, λ ₀ : Wavelength of light in medium, wavelength of light in vacuum π: Pi J: Bessel function
P _n ⁽¹⁾ : Legendre polynomial function (Legendr's function)
d: Particle size μ: Permeability μ ₁ , μ ₂ : Refractive index of light in the medium, Refractive index of light in particles ε: Permittivity σ: Conductivity.

The scattered light intensity I (θ, λ) of the equation (1) is proportional to the reciprocal of ^{λ 4 if α <2 and the parameters other than the wavelength λ are constant.} That is, the smaller the wavelength λ of the light source, the larger the scattered light intensity I (θ, λ).

_{FIG. 12 is a diagram showing the relationship between α and i 1} + i ₂ (θ) defined in the process of deriving the equation (1), and is a diagram when θ = 45 ° as an example. When i ₁ + i ₂ (45 °) is divided into cases of α <2 and 2 ≦ α, the relationship of _{i 1} + i ₂ (45 °) ∝ α ^{6 is established in the case of α <2.} At this time, the scattered light intensity I (45 °, λ) ∝λ ^-4 . Therefore, the smaller the wavelength λ of the light source 20, the larger the scattered light intensity I (θ, λ). In the case of _{2 ≦ α, i 1 + i} 2 (45 °) αα 2, _{i.e., i 1 + i 2 (45} °) αλ relationship ^-2 is established, the scattered light intensity I (45 °, λ) is It does not depend significantly on λ.

(Irradiation area forming means)
The irradiation region forming means includes a light source 20. A known light source can be appropriately used as the light source 20, and for example, an LED light source or a laser light source can be used. By using these light sources 20, for example, an irradiation region having a peak in a wavelength band such as an ultraviolet region, a visible light region, and an infrared region can be formed. As the light source 20, it is preferable to use a light source having a peak of the wavelength spectrum in a wavelength band such as an ultraviolet region, a visible light region, and an infrared region. A plurality of peaks of the wavelength spectrum may be present in any one of the wavelength bands such as the ultraviolet region, the visible light region, and the infrared region, or may be plural over, for example, the ultraviolet region and the visible light region. The number of peaks in the wavelength spectrum may be one or multiple.

The lower limit of the intensity of the light source 20 is preferably 10 W / m ² or more. The upper limit of the intensity of the light source 20 is not particularly limited. If it is smaller than the lower limit, the brightness of the scattered light 51 is small, and it is difficult to clearly visualize the particles. In particular, when an LED light source or a laser light source in which the wavelength band of the light source 20 is limited is used, the optical filter 52 that disperses only a specific wavelength band including the wavelength of the light source 20 is provided in the light receiving portion of the imaging visualization means 15. The influence of light outside the wavelength band, that is, the lighting means can be reduced.

The irradiation region 54 can be formed into various shapes. For example, when the film-like irradiation region 54 is formed, a film of light having a width can be formed so as to extend in the emission axis direction (x direction). The width may be such that it expands in the vertical direction of the exit axis as it goes farther in the exit axis direction (x direction) (in this case, the irradiation region 54 becomes fan-shaped), or the exit shaft remains parallel with a predetermined width. It may have a shape extending in the direction, that is, a square shape. The morphology of the irradiation region 54 is elliptical columnar including columnar, prismatic (including triangular columnar to hexagonal columnar and other polygonal columnar columns), elliptical frustum including truncated cone, angular cone, square film, and exit shaft. Various shapes such as a film shape that gradually expands in the direction perpendicular to the direction (x direction) (trapezoidal film shape 1), a film shape that collects light in the vertical direction and gradually narrows (trapezoidal film shape 2), and the like. Can be in the form. Further, the elliptical cone trapezoidal shape and the square cone trapezoidal shape may be gradually expanded in the direction perpendicular to the exit axis direction (x direction) (at least one of the y direction and the z direction), or in the vertical direction (the vertical direction (x direction). It may be a form in which light is collected in at least one of the y direction and the z direction) and gradually narrowed. Further, after emission, the light may be focused in the vertical direction (yz plane direction) and gradually narrowed to form a focal point in front of the irradiation axis direction (x direction). As shown in FIG. 24, the condensing means a means for collecting the light irradiated in the emission axis direction by the irradiation region forming means in front of the emission axis direction. The irradiation region formed by the condensing means is referred to as a condensing irradiation region. The form of condensing is not particularly limited, but as an example, a film-like condensing irradiation region 54a formed by narrowing the light emitted from the light source 20 in the z direction toward a distance in the irradiation axis direction (x direction). Can be mentioned. Here, the narrowing direction is the z direction, but it may be narrowed in any direction on the zy plane. In addition, the form of the focused irradiation region 54a may be a cylindrical form or a form that converges at a predetermined point in front of the exit axis direction, but is not limited to this (not limited to this). do not).

When the laser light generator 2 is used as the light source 20, it is possible to take a means of forming the irradiation region 54 by reciprocating the laser light LO at a high speed between predetermined amplitudes. Since the emitted laser light LO is not branched, there is an advantage that the irradiation region 54 can be formed without weakening the intensity of the laser light LO. Characteristically, the laser beam LO is reciprocated in the vertical direction (y direction) with a predetermined amplitude to form a light film that spreads in the vertical direction. Then, the light is focused in the left-right direction (z direction) in front of the emission axis direction (x direction) of the light film to form a focused irradiation region 54a. As a result, the focused irradiation region 54a is focused in the direction of reducing the thickness of the light film (z direction), so that the initial thickness of the laser beam LO emitted from the light source 20 (about 2 to 3 mm). Will be thinner than.

As an example of other means, in FIG. 4, a galvanometer mirror (laser light scanning means) 12A and a cylindrical lens (parallelizing means) 12B that receive the laser light LO emitted from the laser light generator 2 and scan a predetermined angle range. Indicates the one that uses.

As another example, those shown in FIGS. 2 and 3 can be mentioned. In this example, a laser beam generator 2, a scanning means 12A such as a galvano mirror, a first mirror 4, a second mirror 5, a Fresnel lens 6, and a casing 11 are provided. In this example, the first mirror 4, the second mirror 5, and the Fresnel lens 6 constitute the parallelizing means 12B.
The laser light LO emitted forward from the laser light generator 2 enters the scanning means 12A after being angle-converted by the angle conversion mirrors 7 and 8 whose details are not shown, and the scanning means 12A enters the scanning means 12A. Receive and spread in a fan shape.

The laser light from the scanning means 12A is reflected between the first mirror 4 and the second mirror 5 which face each other in parallel in the front-rear direction, and becomes a wider fan-shaped scanning light. That is, the light reflected by the first mirror 4 is incident on the second mirror 5 and emitted forward by the second mirror 5. The emitted light is emitted into the air as parallel beam light by passing through the parallelizing means 12B. If a plastic lens is used as the parallelizing means 12B, it is advantageous in terms of cost.

As a result, even if the deflection angle of the scanning means 12A is θ', it can be emitted as a wide parallel beam light as in the case where the scanning means 12A is virtually installed at the rear position P.
As the scanning means, a galvano mirror, a resonant mirror, a polygon mirror and the like can be used. The runout angle θ'by the scanning means 12A can be appropriately selected or adjusted. As a result, the width of the parallel beam light can be adjusted.

Further, as another example of the irradiation region forming means, a lenticular lens (not shown) or a laser line generator lens (FIG. 20) that receives the light LO and spreads the laser beam to form the irradiation region 54 can also be used. When a lenticular lens is used, an LED light source can also be used for the light L. By providing the lenticular lens near the irradiation port of the optical LO, the optical LO becomes flat and the irradiation region 54 is irradiated. By providing the laser line generator lens 12C, the laser beam is spread in the direction perpendicular to the x direction (a predetermined uniaxial direction on the yz plane) toward the distance (x direction) in the emission axis direction to form the irradiation region 54. can do. Since the irradiation region 54 formed through the laser line generator lens 12C has uniform brightness in the vertical direction at a predetermined position in the x direction, the use of the lens is preferable for visualizing particles.

When an LED light source is used as the light source 20, examples of products such as "Parallell Eye D" and "Parallell Eye M" manufactured by Shin Nippon Air Technologies Co., Ltd. can be exemplified.

When a laser light source is used as the light source 20, a known laser can be used. For example, the second harmonic of the Nd: YAG laser (wavelength spectrum peak 532 nm, green laser), argon ion laser (wavelength spectrum peak 488.5 nm, 514.5 nm), HeNe (helium neon) laser (wavelength spectrum peak). 632.8 nm), semiconductor lasers, high power lasers and pulsed lasers can be mentioned.

(Lighting means)
The illuminating means 53 has a peak B in the wavelength spectrum. The lighting means 53 is not particularly limited, and examples thereof include fluorescent lamps, LED lighting, mercury lamps, sodium lamps, neon lamps, hydrogen discharge tubes, and metal halide lamps. In particular, a fluorescent lamp or a metal halide lamp is preferable because the peak curve of the wavelength spectrum is steep. Here, the steep peak is not particularly limited, but refers to a peak having a full width at half maximum of 50 nm or less. If it is the peak, the illumination light by the illumination means 53 and the scattered light 51 can be effectively separated, which is preferable.

The metal halide lamp is a high-pressure discharge lamp in which various metal halides are sealed in a high vapor pressure mercury discharge, and various metal halides can be selected, and the discharge lamp has various aspects of wavelength spectra. For example, a lamp containing sodium iodide, thallium iodide, and indium iodide, a lamp containing scandium iodide and sodium iodide, a lamp containing tin halide, and dysprosium iodide and thallium iodide, respectively. Can be mentioned as a lamp.

Here, the peak curve 70 will be described with reference to FIG. 19. In the spectrum curve, the point on the short wavelength side of the points at which the wavelength spectrum starts to deviate from the baseline is the peak start 70s, and the point on the long wavelength side is the peak end. 70e, when the maximum point of the wavelength spectrum is the peak 62, the curve starts from the peak start 70s, passes through the peak 62 (that is, the point where the relative intensity is the largest in the peak curve 70), and reaches the peak end 70e. To say. The wavelength showing the peak 62 is also referred to as “peak wavelength 62a”. The use of the light source 20 and the lighting means 53 so that the peak wavelength of the wavelength spectrum of the light source 20 and the peak wavelength of the wavelength spectrum of the lighting means 53 are equal should be avoided. If those having the same peak wavelength are used, it becomes difficult to disperse the illumination light emitted by the illumination means 53 and the scattered light 51. The baseline refers to a straight line connecting the peak start 70s and the peak end 70e. For example, in FIG. 19, it coincides with the horizontal axis (wavelength).

The lighting means 53 may have one peak B in the wavelength spectrum, or may have a peak B group including a plurality of peaks B1, B2, B3, ... In the wavelength spectrum. ..

_{The wavelength difference between the wavelength λ B} indicating the peak B of the wavelength spectrum of the lighting means 53 _{and the wavelength λ A} indicating the peak A of the wavelength spectrum of the scattered light 51 is 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more. It is good to be there. If the wavelength difference is less than 5 nm, when the scattered light 51 is imaged, the light of the lighting means 53 is also easily imaged, and the background of the scattered light 51 and the captured image does not have good contrast.

(Optical filter)
The optical filter 52 transmits light in a specific wavelength band among the incident light, and attenuates light in a wavelength band other than the specific wavelength band. The optical filter 52 is not particularly limited, and a bandpass filter can be exemplified. A bandpass filter is preferable because it can transmit light in a wavelength band having a center wavelength of 532 nm and a half-value full width of 6 nm, and can attenuate light on a shorter wavelength side or a longer wavelength side than this wavelength band. When the illuminating means 53 has a peak B group consisting of a plurality of peaks B1, B2, B3, ..., A bandpass filter can be preferably used. For example, when the illuminating means 53 has two peaks, in the wavelength band between the wavelength lambda _B2 wavelength lambda _B1 and peak B2 of adjacent peaks B1 (i.e., between the lambda _B1 to [lambda] _B2), when there is a wavelength band of the band-pass filter, the influence of the illumination means Can be suppressed. Specifically, a bandpass filter having a short wavelength end _{larger than λ B1} and a long wavelength end _{smaller than λ B2 in the} wavelength band of the bandpass filter can be exemplified. Further, the short _{wavelength end in the wavelength band of the bandpass filter may be larger than λ B2} , or the long wavelength end in the wavelength band of the bandpass filter may be smaller than _{λ B1.}

FIG. 5 shows the relationship between the transmitted wavelength band and the light transmittance (percentage of the relative intensity of transmitted light when the relative intensity of the incident light on the optical filter 52 is 100% at a specific wavelength) of the optical filter 52. This will be described with reference to the light transmittance curve 52P. This explanation is an example. The optical filter 52 has a light transmittance curve 52P. The light transmittance curve 52P increases from 0 to 0 from the short wavelength side to the long wavelength side, passes through a maximum value P (hereinafter, also referred to as “maximum light transmittance P”), and then decreases to 0. Is what becomes. The wavelength at the time of the maximum light transmittance P is called _{the center wavelength λ c of the optical filter 52.} Further, the maximum value from the short wavelength side wavelength half of the light transmission P / 2 of the P lambda _c1, lambda When _c2, the wavelength band of between lambda _c1 to [lambda] _c2 as the full width at half maximum lambda] w. For example, in _{the case of an optical filter 52 having a center wavelength λ c} of 600 nm and a full width at half maximum of 20 nm, λ _c1 is 590 _{nm and λ c2} is 610 nm. Although it cannot be said unconditionally because it differs depending on the optical filter 52, if the maximum light transmittance P is 60% or more, preferably 70% or more, more preferably 80% or more, and further preferably 90% or more, the center wavelength is near _λc. Incident light having a wavelength of is preferably transmitted, and clear visualization is possible.

_{Explaining with reference to FIG. 6, the wavelength λ A} indicating the peak A of the wavelength spectrum of the scattered light 51 is _{the center wavelength λ C of the} optical filter 52 rather than the _{wavelength λ B} indicating the peak B of the wavelength spectrum of the lighting means 53. A form close to is desirable. In FIG. 6, the relative intensity of the peak A of the scattered light 51 and the relative intensity of the peak B of the illuminating means 53 are read on the vertical axis on the right side, and the light transmittance 52P of the optical filter is read on the vertical axis on the left side. The relative intensity of a peak B is greater than the relative intensity of the peak A, the wavelength lambda _B of the peak B than the wavelength lambda _A peak A is away from the center wavelength lambda _C of the optical filter, the peak B in the optical filter light The transmittance is relatively low. As a result, the scattered light 51 is remarkably imaged. In other words, since the optical filter has "the light transmittance is the light transmittance of the peak A> the light transmittance of the peak B", the scattered light 51 is conspicuously imaged.

As shown in FIG. 8, when there is a peak B group consisting of a plurality of peaks B1, B2, B3, ... In the wavelength spectrum of the illumination means 53, the wavelength λ _{B1 indicating the peaks B1, B2, B3, ...} , Λ _B2 , λ _B3 ..., _{Scattered light 51 having a peak A at a wavelength λ A} is generated, the scattered light 51 is transmitted with high light transmittance, and the peak B group of the wavelength spectrum of the illumination means 53 is transmitted. An optical filter 52 that transmits or blocks light with a low light transmittance may be provided. The wavelength spectrum 90 of the illuminating means 53 has a plurality of peaks, the peak having the maximum relative intensity is defined as peak B1, and the peak having the second largest relative intensity is defined as peak B2. It is preferable to generate the scattered light 51 having a peak A at a _{wavelength λ A shorter than the wavelength λ B1} (= 548 nm) indicating the peak B1 of the scattered light 51, for example, 532 nm. In FIG. 8, the relative intensity of the peak A of the scattered light 51 and the relative intensity of the peak B of the illuminating means 53 are read on the vertical axis on the right side, and the light transmittance 52P of the optical filter is read on the vertical axis on the left side.

When the wavelength spectrum of the illuminating means 53 has a peak B group consisting of a plurality of peaks B, the optical filter has a light transmittance of any one of the peak A's light transmittance> the peak B group. A form that satisfies the light transmittance is preferable. The peak of any one of the peak B groups may be a peak selected indiscriminately from the peak B group, or a specific peak selected from the peak B group. In this form, the scattered light 51 can be imaged with good contrast, and the particles can be easily visualized.

Further, as shown in FIG. 7, it is desirable that the relative intensity of the peak A of the wavelength spectrum of the scattered light 51 is larger than the relative intensity of the peak B of the illuminating means 53. Since the relative intensity of the illuminating means 53 is relatively small, the scattered light 51 is conspicuously imaged. In FIG. 7, the relative intensity of the peak A of the scattered light 51 and the relative intensity of the peak B of the lighting means 53 are read on the vertical axis on the right side, and the light transmittance 52P of the optical filter is read on the vertical axis on the left side.

Further, in this embodiment, the wavelength of the peak A is included in the half-value full width λw of the optical filter 52, and if the wavelength of the peak A is within the wavelength band of the half-value full width λw, the light transmission of the optical filter is performed. Since the rate is relatively high, the scattered light 51 transmitted through the optical filter 52 is imaged with a large relative intensity.

The form in which the wavelength of peak B in the wavelength spectrum of the illumination means 53 is outside the wavelength band of the half-value full width λw of the optical filter, particularly the form in which the optical filter 52 blocks light of the wavelength of peak B is optical. The relative intensity of the illumination means 53 that passes through the filter 52 is small, which is preferable.

The full width at half maximum λw of the optical filter can be variously selected by corresponding to the lighting means 53. For example, the upper limit of the full width at half maximum λw is 10 nm or less, preferably 6 nm or less, more preferably 3 nm or less, and the lower limit is 0.5 nm or more. If the full width at half maximum λw is more than 10 nm, a relatively large amount of light from the lighting means is transmitted, and the difference in brightness between the scattered light 51 and the lighting becomes small. If it is less than 0.5 nm, it may be difficult to manufacture.

(particle)
This embodiment relates to a system for visualizing particles having a diameter on the order of nm to μm or larger. For example, a particle having a diameter of α (= πd / λ) <2 and a particle having a diameter of α ≧ 2. It can also be applied to particle visualization. Further, regardless of the wavelength of the scattered light, not only the particles having a diameter of 50 to 100 μm can be visualized, but also the particles having a diameter of 0.1 μm or more and less than 0.5 μm, the particles having a diameter of 0.5 μm or more and less than 1 μm, and the diameter. It is also applicable to visualization of particles of 1 μm or more and less than 5 μm, and particles of 5 μm or more.

Examples of the particles visualized in the present invention include powders, sprays, aerosols, suspensions, emulsions, oil particles having a diameter of about 1 μm by a Ruskin nozzle, and bubbles in a liquid.

Examples of particles suspended in a liquid include aluminum powder, polymer particles, air bubbles, glass balloons, milk, water-based paint, and Ishimatsuko.

Examples of particles suspended in gas include spraying water and glycerin, chemical reaction of ammonium chloride, burning and heating of smoke (chips, etc.) and magnesium oxide, solids such as alumina and silica (fluidization), and silica (fluidized). Examples _{thereof include powders such as SiO 2} ) and titania (TiO ₂ ), PSL particles, and the like. In particular, _{powders such as silica (SiO 2} ) and titania (TiO ₂ ) have a particle size of about 0.5 to 5 μm, and some PSL particles have a particle size of about 0.1 μm.

In addition to the above, for example, smog, virus, carbon black, gas molecule, pigment, or bacterium having a relatively small diameter, for example, a diameter of less than 1 μm may be used, or a relatively large diameter, for example, a diameter of 1 μm or more. It may be fume, dust, pollen, oil droplets, fly ash, dust, powdered milk.

(Scattered light)
The scattered light 51 refers to light emitted in various directions by the particles when the light is incident on the particles. When a light source 20 having a peak at a specific wavelength in the wavelength spectrum is incident on a particle, the particle mainly emits scattered light 51 having a peak at the specific wavelength. In order to distinguish it from the peak B of the wavelength spectrum of the lighting means 53, the peak of the wavelength spectrum of the scattered light 51 is also referred to as a peak A.

Explaining with reference to FIG. 22, the particles 59 that have received the incident light in the direction of the arrow in the illustrated example emit scattered light 51v and 51h to the surroundings. Here, the polarization direction of the scattered light 51v and the polarization direction of the scattered light 51h are orthogonal to each other. The logarithmic scale extending in the vertical direction on the left side of the paper represents the relative intensity of the scattered light, D1 is the position where the relative intensity is 1, D10 is the position where the relative intensity is 10, and D100 is the relative intensity of 100. Represents the position, ... In the illustrated example, the wavelength of the incident light is 532 nm, the particle size is 0.5 μm, and the refractive index of the particles is 1.59. For example, looking at the scattered light 51v, it can be seen that the distribution of the forward scattered light is larger than the distribution of the backscattered light. The same can be seen for the scattered light distribution of the scattered light 51h.

FIG. 23 shows the scattered light distribution of another particle. In the illustrated example, the wavelength of the incident light is 532 nm, the particle size is 1.016 μm, and the refractive index of the particles is 1.59. In the particles of this illustrated example, the distribution of the forward scattered light is large for both the scattered light 51v and the scattered light 51h. Also, the distribution of backscattered light is not as large as the distribution of forward scattered light, but it has a certain size. This means a position where the backscattered light can be imaged, for example, 120 ° ≤ θ ≤ 180 °, preferably 135 ° ≤ θ ≤ 180 °, more preferably 150 ° ≤ θ ≤ 180 °, and particularly preferably 170 ° ≤ θ. It is shown that the flow of scattered light can be imaged even if the imaging visualization means is installed at ≦ 180 °. Needless to say, even if the imaging visualization means is installed at a position where the forward scattered light can be imaged, the flow of the scattered light can be imaged, and in some cases, the scattered light other than the forward scattered light and the backscattered light may be used. Can be imaged.

Here, in the scattered light distribution of FIGS. 22 and 23, the particle is positioned at the center, the angle φ = 0 ° in the right direction of the paper surface, and the angle φ rotated 90 ° counterclockwise from 0 ° is 90 °. The angle φ rotated 90 ° counterclockwise is 180 °, the angle φ rotated 90 ° counterclockwise is 270 °, and the angle φ rotated 90 ° counterclockwise is 360 ° ( = 0 °). Then, among the scattered light distributions emitted from the particles, the scattered light distributions in which the angles φ are in the range of 270 ° <φ ≦ 360 ° and 0 ° ≦ φ <90 ° are particularly referred to as forward scattered light. Further, the scattered light distribution in the range of approximately φ120 ° ≦ φ ≦ 240 ° is particularly referred to as backscattered light.

(Image imaging visualization means)
The imaging visualization means 15 is a means for visualizing the particles by imaging the scattered light 51 emitted by the particles irradiated with light from the light source 20. A known camera can be appropriately used as the imaging visualization means 15. In addition, it is equipped with an image pickup tube camera equipped with an image sensor that utilizes the avalanche multiplication phenomenon of electric charge that occurs in an amorphous selenium photoelectric film under a high electric field, and an analog differentiation processing device that performs analog differentiation processing of the image signal captured by the image pickup tube camera. An image pickup visualization means 15 configured to visualize particles based on a differentially processed image by this analog differential device is also preferable. Further, an API major camera (Hamamatsu Photonics), a CCD camera, a CMOS camera, and a camera whose definition has been increasing in recent years may be used as the imaging visualization means 15. As an example, the imaging visualization means 15 is installed so that the light receiving shaft OX is directed to the region where the scattered light 51 is generated.

(Particle visualization method)
The particle visualization method of this embodiment can be performed in the following steps. In the particle visualization method, first, (1) an irradiation region forming step of forming an irradiation region 54 by light irradiation from the light source 20 is performed, and then (2) light irradiation from the light source 20 is received and the particles float in the irradiation region. A spectroscopic step is performed in which the scattered light 51 emitted by the particles is transmitted through a part of the contained light to be transmitted light and the rest is attenuated by the optical filter 52, and the transmitted light is obtained by the optical filter 52. ) An imaging visualization step of imaging the scattered light 51 of the transmitted light to visualize the particles is performed. This particle visualization method can be performed in an environment irradiated by the lighting means, and the formation of the environment irradiated by the lighting means 53 is performed prior to each of the above-mentioned steps (steps (1) to (3)). It may be performed in the middle of each step, for example, between the steps (1) and (2).

Under the environment irradiated by the illumination means 53, the irradiation region 54 was formed by irradiation with light from the light source 20 by the irradiation region forming means. Light including scattered light 51 emitted by particles floating in the irradiation region 54 was incident on the optical filter 52. The particles were visualized by imaging the transmitted light transmitted through the optical filter 52 with the imaging visualization means 15. The second harmonic (532 nm, green laser) of the Nd: YAG laser is used as the light source 20, one of the fluorescent lamp, the metal halide lamp, and the incandescent lamp is used as the illumination means 53, and the optical filter 52 is used. A CMOS camera was used for this. The optical filter 52 was selected from the four types shown in Table 1 and used. The wavelength spectra 101 of the fluorescent lamp, the metal halide lamp, and the incandescent lamp are shown in FIGS. 9 to 11. Here, the light from the incandescent lamp includes a lot of light in the near infrared region and the infrared region. The four types of optical filters shown in Table 1 are compared under each ambient light. Since these four types of optical filters have different transmittances in the near-infrared region and its vicinity, light in the near-infrared region and its vicinity is used. It is not possible to make a correct comparison between each optical filter if is included. Therefore, by installing a bandpass filter (BPF) with a transmission range of 450 to 610 nm and transmitting the irradiation light of the incandescent lamp through this bandpass filter, the near-infrared region and the near-infrared region of the wavelength band of the irradiation light of the incandescent lamp and Light in the wavelength band in the vicinity was removed. FIG. 11 shows the wavelength spectrum of an incandescent lamp that has passed through a bandpass filter having a transmission range of 450 to 610 nm.

(Visualization test)
The scattered light 101 was imaged in Test Examples 1 to 3 shown below to visualize the particles.
<Test Example 1-1>
The lighting means is a fluorescent lamp, and the optical filter No. 4 was used.
<Test Example 1-2>
The lighting means is a fluorescent lamp, and the optical filter No. 3 was used.
<Test Example 1-3>
The lighting means is a fluorescent lamp, and the optical filter No. 2 was used.
<Test Example 1-4>
The lighting means is a fluorescent lamp, and the optical filter No. 1 was used.
The captured images are shown in FIGS. 13 and 14.

In Test Example 1-1 and Test Example 1-2, scattered light 101 was confirmed, and light 102 of the lighting means was also confirmed. Since the amount of light 102 of the lighting means is large, it cannot be said that the scattered light 101 is conspicuously imaged. In Test Example 1-3 and Test Example 1-4, the half-value full width of the optical filter is relatively narrow, most of the light 102 of the lighting means is attenuated by the optical filter, and the scattered light 101 is conspicuously imaged. The particles could be clearly visualized.

<Test Example 2-1>
The lighting means is a metal halide lamp, and the optical filter No. 4 was used.
<Test Example 2-2>
The lighting means is a metal halide lamp, and the optical filter No. 3 was used.
<Test Example 2-3>
The lighting means is a metal halide lamp, and the optical filter No. 2 was used.
<Test Example 2-4>
The lighting means is a metal halide lamp, and the optical filter No. 1 was used.
The captured images are shown in FIGS. 15 and 16.

In Test Example 2-1 and Test Example 2-2, scattered light 101 was confirmed, and light 102 of the lighting means was also confirmed. Since the amount of light 102 of the lighting means is large, it cannot be said that the scattered light 101 is conspicuously imaged. In Test Example 2-3 and Test Example 2-4, the half-value full width of the optical filter is relatively narrow, most of the light 102 of the lighting means is attenuated by the optical filter, and the scattered light 101 is conspicuously imaged. The particles could be clearly visualized.

<Test Example 3-1>
The lighting means is an incandescent lamp, and the optical filter No. 4 was used.
<Test Example 3-2>
The lighting means is an incandescent lamp, and the optical filter No. 3 was used.
<Test Example 3-3>
The lighting means is an incandescent lamp, and the optical filter No. 2 was used.
<Test Example 3-4>
The lighting means is an incandescent lamp, and the optical filter No. 1 was used.
The captured images are shown in FIGS. 17 and 18.

In Test Example 3-1 and Test Example 3-2, scattered light 101 was confirmed, and light 102 of the lighting means was also confirmed. The amount of light 102 of the lighting means was smaller than that of Test Example 1 and Test Example 2, and the scattered light 101 was conspicuously imaged, and the particles could be clearly visualized. In Test Example 3-3 and Test Example 3-4, the half-value full width of the optical filter is relatively narrow, most of the light 102 of the lighting means is attenuated by the optical filter, and the scattered light 101 is conspicuously imaged. The particles could be clearly visualized.

(Brightness value of lighting means)
Light is saturated in each of the captured images of Test Example 1-1 to Test Example 1-4, Test Example 2-1 to Test Example 2-4, and Test Example 3-1 to Test Example 3-4. The brightness values of the region 110 (length 20 × width 20 pixels) without scattered light were compared.

Regarding Test Example 1, the brightness value of the region 110 in the case of Test Example 1-1, that is, when an optical filter having a full width at half maximum of 40 nm is used, is set to 1, and the region 110 of Test Examples 1-2 to Test Example 1-4. The brightness value was calculated. Similarly, regarding Test Example 2, the region of Test Example 2-2-2 to Test Example 2-4 is set to 1 when the brightness value of the region 110 is set to 1 in the case of Test Example 2-1. The brightness value of 110 was calculated. Similarly, regarding Test Example 3, the region of Test Example 3-2 to Test Example 3-4 is set to 1 when the brightness value of the region 110 is set to 1 in the case of Test Example 3-1. The brightness value of 110 was calculated. The calculation result is shown in FIG.

In the figure, it is shown that the smaller the luminance value is, the darker the background of the captured image is. The narrower the full width at half maximum of the optical filter, the smaller the luminance value. Characteristically, focusing on the test examples when the half-value full width of the optical filter is 10 nm, that is, Test Example 1-3, Test Example 2-3, and Test Example 3-3, the lighting means is a fluorescent lamp or a metal halide lamp. The brightness value when the lighting means is incandescent lamp is smaller than the brightness value when the lighting means is incandescent lamp. That is, under ambient light having a steep peak in the wavelength spectrum such as a fluorescent lamp or a metal halide lamp, the influence of the ambient light can be effectively reduced by using an optical filter having a full width at half maximum of 10 nm or less.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the embodiments, and can be variously modified and implemented without departing from the spirit of the present invention.

The present invention can be used both outdoors and indoors where direct sunlight is excluded. Especially indoors, particles are scattered at manufacturing sites such as semiconductors, liquid crystals, pharmaceuticals, foods, and medical sites. It is applicable to all problematic fields and all fields where particles are visualized in liquids such as water in which illumination light is present and in solids such as glass. It is also applicable to fluid flow visualization and particle image velocimetry using tracer particles.

20 Light source 53 Illumination means 51 Scattered light 52 Optical filter 54 Irradiation area 15 Imaging visualization means

Claims (6)

It is a particle visualization system used in an environment illuminated by lighting means.
Irradiation area forming means for forming an irradiation area by light irradiation from a light source in the environment, and
An optical filter that receives light irradiation from the light source, transmits scattered light emitted by particles floating in the irradiation region, transmits a part of the light to be transmitted light, and attenuates the rest.
It is provided with an imaging visualization means for imaging the scattered light of the transmitted light and visualizing the particles.
The scattered light has a peak A in the wavelength spectrum of the scattered light.
The illuminating means has a peak B having a full width at half maximum of 50 nm or less in the wavelength spectrum of the illuminating means.
The optical filter is
The full width at half maximum is 10 nm or less,
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of the peak B.
The wavelength of the peak A is within the wavelength band of the full width at half maximum of the optical filter.
A particle visualization system characterized by this. The particles are dust,
The particle visualization system according to claim 1. The optical filter blocks light having a wavelength of the peak B.
The particle visualization system according to claim 1. The peak B is a group of peaks B composed of a plurality of peaks B.
The optical filter is
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of any one peak in the peak B group.
The particle visualization system according to claim 1. The lighting means is a fluorescent lamp or a metal halide lamp.
The particle visualization system according to claim 1. It is a particle visualization method performed in an environment illuminated by lighting means.
An irradiation region forming step of forming an irradiation region by irradiating light from a light source in the environment, and
The optical filter has an optical filter that transmits a part of the light including scattered light emitted by particles floating in the irradiation region to be transmitted light and attenuates the rest by receiving the light irradiation from the light source. The spectroscopic step of obtaining the transmitted light and
It is provided with an imaging visualization step of imaging the scattered light of the transmitted light and visualizing the particles.
The scattered light has a peak A in the wavelength spectrum of the scattered light.
The illuminating means has a peak B having a full width at half maximum of 50 nm or less in the wavelength spectrum of the illuminating means.
The optical filter is
The full width at half maximum is 10 nm or less,
The light transmittance satisfies the light transmittance of the peak A> the light transmittance of the peak B.
The wavelength of the peak A is within the wavelength band of the full width at half maximum of the optical filter.
A particle visualization method characterized by this.

Images