JPH0735764A - Method for visualizing gas flow - Google Patents

Abstract

PURPOSE:To clearly visualize gas flow. CONSTITUTION:Pure water mist is mixed into the gas flow to be visualized. Beam-like laser light including wavelength in a specific visible light region is repetitively scanned from a laser oscillator 3 to be applied to the gas flow, and scattered light generated at this time from the pure water mist is recognized through an optical filter having relatively high transmissivity only for the range of laser light oscillation wavelength. Therefore intensity of the scattered light is large, so that the laser oscillator 3 can be downsized. Further air current can be clearly visualized in combination with transmission characteristics of the optical filter 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visualizing an air flow, in which a tracer mixed in the air flow to be visualized is irradiated with a laser beam and the scattered light generated at that time is recognized to visualize the air flow. It is about.

[0002]

2. Description of the Related Art Conventionally, a so-called tracer method has been widely used for visualizing an air flow. This is to mix a tracer into the airflow to be visualized and to visually recognize the movement of the airflow by the movement of the tracer.In many cases, the movement of the tracer itself is captured by a video camera or the like. I try to record it.

In the conventional method, as tracers, light fine particles that easily float in the airflow, for example, smoke of incense sticks or fine powder of chemically synthesized powder, or fine particles made from clean water (pure water) are used. A water drop mist was used.

[0004]

However, among the above-mentioned conventional techniques, according to the former method of using smoke or fine powder as a tracer, these particles are present on the surface of the object in the air stream to be visualized or in the periphery thereof. Adhere to the surface and cause surface contamination. Therefore, it cannot be used in a clean space such as a clean room.

On the other hand, according to the latter method of using a fine water droplet mist made of pure water as a tracer, even if the mist adheres to the surface, it evaporates in a short time, which may cause the above surface contamination. There is no.

However, the water droplet mist evaporates or diffuses to the surroundings during a short time when it is conveyed by an air flow, and the number concentration thereof is significantly reduced, resulting in the sharpness of an image taken by a video camera or the like. However, there was a problem that the air flow could not be sufficiently observed especially on the downstream side of the air flow or in a portion where the turbulence was large.

Further, conventionally, light is radiated into the air stream by an appropriate illuminating device and the reflected light from the fine water droplet mist is observed, but in order to improve the sharpness of the image, a large illuminating device is used. A large-scale light source device was required, such as illuminating with a laser beam or radiating a laser beam emitted from a high-power laser oscillator in a sheet form.

Moreover, when visualizing a wide space using a laser beam, normally, a beam-shaped laser beam is spread by a cylindrical lens or the like to irradiate the space to be visualized as a planar light. The intensity of the laser light in the form of a circle is much lower than the intensity of the laser light in the form of a beam. Therefore, the reflected light from the fine water droplet mist was weakened by that amount, and a clear image could not be obtained.

The present invention has been made in view of the above points, and it is possible to obtain a clear image even when photographed by a video camera or the like without causing surface contamination, and to reduce the size of a necessary apparatus. It aims at providing the visualization method of.

[0010]

In order to achieve the above-mentioned object, according to claim 1, in an air stream to be visualized,
A tracer that moves by this air flow is mixed, and a beam-shaped laser light containing a wavelength in a specific visible light region is repeatedly scanned to irradiate, for example, a specific area of the air flow, and scattered light generated at that time Is provided through an optical filter having a relatively high transmittance only in the oscillation wavelength range of the laser light, and a method for visualizing an air flow is provided.

Here, in order to irradiate the beam-shaped laser light by repeatedly scanning the specific area, for example, the laser light oscillation device itself is rotated within a range of a predetermined angle, for example. The mirror may be once reflected so that the reflected light irradiates a specific area, and the mirror may be rotated within a range of a predetermined angle. In this case, the latter is practically preferable because it does not affect the laser light oscillation device.

The number of scans per unit time at that time is preferably about 60 times or more per second. This is because, when visually recognized, the images are recognized as continuous images due to the afterimage phenomenon of vision.

Specific means for recognizing the scattered light include, in addition to the direct visual recognition, for example, imaging with a video camera and photography with an optical camera.

In the structure according to claim 1, the beam-shaped laser light containing a wavelength in a specific visible light region is ultraviolet (wavelength 390 nm or less) or infrared (8 nm) for the following reason.
Laser light that does not contain (00 nm or more) is preferable.

That is, ultraviolet rays have a strong chemical action, which is also called "actinic rays", and when they are irradiated in the air, they may generate ozone, or when they enter human eyes, they may cause visual impairment. Absent. In addition, in the photolithography process in semiconductor manufacturing, a chemical called a resist that reacts with light of a specific wavelength is used, and the reaction wavelength is 365 nm (i-line) or the like, so the place of use or the like is limited.

On the other hand, infrared rays, unlike ultraviolet rays, have a small chemical action, but when they hit an object, most of them are converted into heat. Infrared rays are also radiated actively from high-temperature objects and the surface of lighting lamps, and infrared rays are also radiated from equipment and instruments at room temperature, as well as the human body. Therefore, when a laser beam containing infrared rays is used, the infrared rays emitted from these various objects are mixed with the scattered light from the water droplet mist mixed in the airflow, making it difficult to separate the two even using an optical filter. Because there is.

According to a second aspect of the present invention, there is provided a method for visualizing an air flow, characterized in that laser light from an argon (Ar ⁺ ) laser is used in the method for visualizing the air flow.

According to a third aspect of the present invention, there is provided a method for visualizing an air flow, wherein a water droplet mist generated from pure water as a raw material is used as the tracer. In this case, in order to generate a water droplet mist of pure water, a method of vibrating the pure water in the water tank with ultrasonic waves to generate a mist from that direction, a method of rapidly condensing pure water vapor to generate a pure water mist Etc. can be used.

[0019]

According to the present invention, when the laser light is applied to the air flow, the scattered light generated from the tracer in the air flow has a relatively high transmittance only in the oscillation wavelength range of the laser light. Since it is recognized through an optical filter,
The component of the illumination light that comes in as stray light (light that reduces the contrast) can be minimized. Therefore, when this is photographed with a video camera or the like, the sharpness of the tracer in the image is improved.

By the way, a fluorescent lamp having a spectral distribution as shown in FIGS. 1, 2 and 3 is used for illumination of a windowless building factory (clean room for semiconductor manufacturing, etc.) in recent years. The daylight white fluorescent lamp shown in 2 is often used. On the other hand, in a special environment, for example, a photolithography process in semiconductor manufacturing, a pure yellow colored fluorescent lamp whose spectral distribution is shown in FIG. 4 is used.

These spectral distributions are distributed over the entire wavelength range of visible light as can be seen from FIGS. 1 to 4, but in the present invention, the laser oscillation light emits light of a specific wavelength (line spectrum). Focusing on the above, by limiting the transmission characteristic of the optical filter to only a specific wavelength as much as possible, it is possible to suppress the amount of stray light entering from the background or other illumination light and obtain a clear visualized image.

By using a beam laser as the irradiation light and repeatedly scanning the visualization space at a high frequency, the intensity of the scattered light can be increased and the light source device itself can be downsized. is there. Moreover, since the laser light can be conveyed by an optical fiber or the like, the distance between the light source device main body and the visualization space can be increased, and thereby the air flow in the visualization space can be prevented from being disturbed.

Further, since the laser light can be distributed by a half mirror or the like, it is possible to visualize the air flow at a plurality of places with one light source device.

According to the second aspect, laser light from an argon (Ar ⁺ ) laser is used, but the argon laser can easily obtain a relatively high output of, for example, about several tens W and is easy to handle. is there.

Moreover, in the Ar ⁺ laser-excited dye laser, it is possible to select 400 to 1000 nm by selecting a dye.
The continuous oscillation in the wavelength range of is obtained, and by appropriately setting the oscillation wavelength according to the illumination conditions to be used,
It is possible to obtain clear images.

According to the third aspect, since the water droplet mist generated from pure water is used as the tracer, impurities do not remain even when the water droplet mist evaporates, and the surface of the object or the room Never pollute.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows the configuration of a basic system for carrying out the present embodiment. Reference numeral 1 denotes a mist generator for generating pure water mist by a rapid cooling method of steam. A nozzle device 2 having a large number of nozzles for blowing pure water mist into the airflow space to be visualized is connected.

Reference numeral 3 denotes a laser oscillating device. In this embodiment, an argon laser oscillating device is used, and its oscillation line and relative output have the characteristics shown in the graph of FIG. The laser light emitted from the laser oscillator 3 is conveyed to the vicinity of the airflow space to be visualized by the optical fiber 4, and the beam laser light is provided near the airflow space to be visualized by the lens device 5. It is configured to be emitted toward the vibrating mirror 6.

The vibrating mirror 6 is configured to reciprocally rotate at a frequency of 30 Hz or more by an appropriate driving device (not shown), and reflects the beam-shaped laser light from the lens device 5, By the reciprocating rotary motion, the specific area (cross section) in the airflow space to be visualized is continuously scanned with the reflected light.

Reference numeral 7 denotes a video camera for photographing, and the camera lens 8 of the video camera 7 includes an optical filter 9
Is provided. The spectral sensitivity of the image pickup tube of these video cameras 7 used in this example and the transmission characteristic of the optical filter 9 are as shown in the graph of FIG. 7, and particularly the transmission characteristic of the optical filter 9 is about 475 nm to 525 nm. It has a characteristic of transmitting only light having a wavelength between 2 and 5 with high transmittance.

The image of the airflow space to be visualized, which is captured by the video camera 7, is recorded on the video deck 11 while being confirmed on the monitor 10. Reference numeral 12 is an indoor illumination lamp.

The system for carrying out the present embodiment is configured as described above, and when obtaining a visualized image, first, the mist generator 1 generates pure water mist to visualize the air flow. The laser oscillating device 3 is mixed with the laser oscillating mirror 6 while being mixed in the space and operating the oscillating mirror 6.
A beam-shaped laser beam is emitted toward the vibrating mirror 6.

Then, the laser light is reflected by the vibrating mirror 6, and a specific area (cross section) in the air flow space to be visualized is repeatedly and continuously scanned, and the scattered light from the pure water mist generated at that time is filtered by the optical filter 9. Through the video camera 7.

In this case, the transmission characteristic of the optical filter 9 has such a characteristic that only light having a wavelength between about 475 nm and 525 nm is transmitted with a high transmittance as shown in FIG. 7, and the wavelength band to be transmitted is extremely narrow. It has become a thing. On the other hand, the main wavelength with a large output in the oscillation wavelength group of laser light is 4
Since they are 88.0 nm and 514.5 nm, other stray light is cut through the optical filter 9 by oscillating laser light at such wavelengths, and an image of scattered light from these pure water mists taken by the video camera 7 is taken. Becomes extremely clear. Therefore, in combination with the transmission characteristics of the optical filter 9 described above, it is possible to clearly image the movement of the pure water mist as the tracer.

Further, since the laser light is repeatedly scanned in the airflow space to be visualized, the intensity of scattered light from the pure water mist is high, and a clear image can be obtained from this point as well. . Further, the laser oscillator 3 does not need to have a large output, and the device can be downsized.

Moreover, by setting the laser light oscillated from the laser oscillator 3 to 488.0 nm and 514.5 nm, ultraviolet rays (wavelength 390 nm or less) and infrared rays (800 nm or more) that adversely affect the human body and the observation itself. Is not included, which is also a preferable visualization method in this respect.

Further, since the laser light oscillated from the laser oscillating device 3 can be carried by the optical fiber 4 to the vicinity of the airflow space to be visualized as described above, the laser oscillating device 3 as the light source device is visualized. It can be installed away from the intended airflow space and does not disturb the airflow in the airflow space.

On the other hand, since the pure water mist generated from the mist generator 1 is used as the tracer which emits scattered light, impurities do not remain even when evaporated, and the surface of the object or the room is not contaminated. .

By the way, since the laser light can be distributed by a half mirror or the like, it is possible to visualize the air flow spaces at a plurality of different places at the same time by using one laser oscillator.
FIG. 8 shows a system main part of another embodiment in such a case. The laser oscillation device 3 and an optical fiber for carrying beam-shaped laser light oscillated from the laser oscillation device 3 to the lens device 5 are shown. 4 is the same as that of the first embodiment described above, but in the second embodiment, the lens device 5 is used.
The beam-shaped laser light emitted from the first is first irradiated to the half mirror 21, and the laser light passing through the half mirror 21 is emitted toward the mirror 22.

The laser light reflected by the half mirror 21 is reflected by the mirror 23 and radiated toward the first vibrating mirror 24, while passing through the half mirror 21 and emitted toward the mirror 22. Is the mirror 2
The second vibrating mirror 26 is reflected and is irradiated toward the second vibrating mirror 26.

The first vibrating mirror 24 and the second vibrating mirror 26 are reciprocally rotated by an appropriate driving device (not shown), like the vibrating mirror 6 in the above-described first embodiment. The specific areas P and Q in the different airflow spaces to be visualized are repeatedly irradiated with the laser light, and the corresponding areas are continuously scanned.

According to the second embodiment, it is possible to visualize specific areas P and Q existing in two different airflow spaces by one laser oscillation device 3, respectively.

[0043]

According to the first aspect of the present invention, the intensity of scattered light from the tracer can be increased and the light source device can be downsized. And while irradiating light of a specific wavelength, by transmitting the scattered light from the tracer with an optical filter,
The scattered light of the tracer can be emphasized, and the airflow can be clearly visualized in combination with the magnitude of the scattered light intensity. Moreover, since the laser light can be conveyed by an optical fiber or the like, the distance between the light source device main body and the visualization space can be increased, and thereby the air flow in the visualization space can be prevented from being disturbed. In addition, since the laser light can be distributed by a half mirror or the like, it is possible to visualize the air flow at a plurality of places with one light source device.

According to the second aspect of the present invention, in carrying out the invention of the first aspect, laser light from an argon laser is used, and the main wavelengths of high output in the oscillation wavelength group are 488.0 nm and 514. Since it exists in a narrow wavelength range of 0.5 nm, the transmission characteristics of the optical filter can be limited to these narrow ranges, and stray light can be more effectively prevented from entering. Further, since the argon laser is easy to handle and a relatively high output can be easily obtained, it is easy to make an apparatus and configure a system.

According to the third aspect, while maintaining the effects of the first and second aspects as they are, impurities do not remain even when the water droplet mist evaporates, so that the surface of the equipment and the room are not contaminated. To be Therefore, it can be applied even in a clean room where cleanliness is required.

[Brief description of drawings]

FIG. 1 is a graph showing a spectral distribution of a daylight fluorescent lamp.

FIG. 2 is a graph showing the spectral distribution of a daylight white fluorescent lamp.

FIG. 3 is a graph showing a spectral distribution of a white fluorescent lamp.

FIG. 4 is a graph showing a spectral distribution of a pure yellow colored fluorescent lamp.

FIG. 5 is an explanatory diagram showing the configuration of a system for carrying out the method for visualizing an air flow according to the first embodiment.

FIG. 6 is a graph showing a relationship between an oscillation wavelength of an argon laser and a relative output.

FIG. 7 is an explanatory diagram showing transmission characteristics of an optical filter used in the first embodiment and spectral sensitivity characteristics of an image pickup tube of a video camera.

FIG. 8 is an explanatory diagram showing a main part of a configuration of a system for carrying out a method of visualizing an air flow according to a second embodiment.

[Explanation of symbols]

 1 Mist Generator 3 Laser Oscillator 4 Optical Fiber 5 Lens Device 6 Vibration Mirror 7 Video Camera 9 Optical Filter 10 Monitor

Claims (3)

[Claims] 1. A tracer, which is moved by the air flow, is mixed in the air flow to be visualized, and a beam-shaped laser beam containing a wavelength in a specific visible light region is repeatedly scanned to irradiate the air flow. Then, the scattered light generated at that time is recognized through an optical filter having a relatively high transmittance only in the oscillation wavelength range of the laser light, and a method for visualizing an air flow. 2. The method for visualizing an air flow according to claim 1, wherein the laser light is a laser light from an argon laser. 3. The tracer is a water droplet mist generated from pure water as a raw material.
Visualization method of air flow described in.