JPH04289306A - Method for guiding view line in fog - Google Patents

Abstract

PURPOSE:To prevent traffic disturbance due to fog by arranging a laser beam irradiation device on a road, airport, or harbor, and by irradiating laser beam when fog is generated and visualizing the optical axis of laser reflected and scattered by the fog. CONSTITUTION:The fog produced by a fluid nozzle 3 of a fog generating device 2 is adjusted via a honeycomb wall 5 by compressed air of a certain flow supplied from an air supply pipe 4, and sent into a wind tunnel 1. The laser beam irradiated by a laser beam irradiation device 6 is reflected and scattered by the fog particles, and the optical axis is visualized by emitting red light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for eliminating visual obstruction caused by fog in order to ensure safe passage on roads, ports, and airports.

0002

[Prior Art] One way to fundamentally solve the visibility obstruction caused by fog on roads, ports, airports, etc. is to artificially dissipate the fog. There is. Among these, a reliable, safe and economically practical method is to raise the temperature of the target area and evaporate the fog. For example, in the fog removal method disclosed in Japanese Patent Application No. 01-073168, hot air pipes are placed in areas where fog needs to be dissipated, and warm air is injected from the hot air pipes to reduce the temperature of the target area. This is a method to raise the fog and dissipate the fog.

[0003] There is also a method of using a laser as a countermeasure against fog. For example, Mullany et al. (A.S.
study of Fog Clearing Usin
g a CO2 Laser, J. Aircraft,
Vol. 8, 108-113, 1971) shows that since water absorbs carbon dioxide gas well, carbon dioxide laser can in principle be used for fogging.

0004

[Problem to be solved by the invention] By the way, the method of dissipating fog by blowing warm air is effective when the area to be dissipated (road width x height) is small, such as a road, but it is If the fogging target area is wide, there is a problem that the fogging target area is blown away by the wind. In other words, the area in which fog should be dissipated shifts further downwind from the runway the higher up in the sky. In order to prevent this, for example, if spraying is performed from the windward side, the area of fogging will become unnecessarily wide, which will be economically disadvantageous.

[0005] The method using a laser is, in principle, a method of heating and vaporizing fog. In this case, the first issue is the energy efficiency of the laser. In the case of carbon dioxide laser,
The conversion efficiency from electricity to laser light is only 20%, making it economically difficult to use it for fogging. Furthermore, a problem with laser fogging is that the spatial density of fog particles is small. In other words, the size of the mist droplets and their average spacing are
They are 10 μm and 2 to 3 mm, respectively, and at these levels, the frequency of collision between the laser beam and the fog particles is low, so the efficiency of fog elimination is low. It also involves safety issues since it uses a powerful carbon dioxide laser to irradiate it.

The present invention has been made to solve the problems of the conventional devices described above, and provides a line-of-sight guidance method that enables the operation of a vehicle, aircraft, or ship even in dense fog by guiding the operator's line of sight. This is what we are trying to provide. In addition, by using it in conjunction with the fogging method using hot air jet,
It is possible to eliminate the influence of wind in the fogging method.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention is configured such that a laser beam irradiation device is arranged at a main part of a road, an airport, or a port, and can irradiate the laser beam when fog occurs.

[0008]

[Operation] Laser light irradiated in fog (e.g. He,
Ne laser) is reflected and scattered by fog particles, and its optical axis emits red light and is visualized. As mentioned above, since the spatial density of fog particles is small, the laser light travels straight through the fog without being significantly attenuated. The nature of the fog, which is a disadvantage when using a carbon dioxide laser, is an advantage when using this method. The operator of a car or aircraft can operate the vehicle or aircraft while looking at this visualized optical axis, making it possible to operate the vehicle or aircraft even in dense fog.

[0009] When targeting an airport, it is necessary to use a misting method using hot air injection in addition to the line-of-sight guidance according to the present invention. In the upper atmosphere, where the fog dissipation area is blown away by the influence of the wind, the normal approach route is determined by the visualized optical axis, and when the altitude is lowered and the fog is near the grounding point, the fog is dissipated by the hot air jet. The runway will be visible. Generally, at airfields equipped with instrument guidance equipment, pilots must operate without relying on instruments.
The height above the ground is 60m or 30m to the grounding point. Therefore, short distance guidance by laser light is sufficient. However, even if the approach route can be determined through line-of-sight guidance, it will not be possible to land if the runway cannot be seen, so it is an absolute prerequisite to use fog removal methods in conjunction with the guidance of landing aircraft.

0010

[Example] Figure 1 is a sectional view of the experimental apparatus of the present invention.
2 is a wind tunnel, 2 is a fog generator, 3 is a two-fluid nozzle, 4 is an air pipe, 5 is a honeycomb wall, 6 is a laser beam irradiation device, and 7 is a photocell. As shown in the figure, the experimental equipment is 6 m long.
A fog generator 2 is attached to one end of a wind tunnel 1 having a cross section of 2 m x 2 m. There is a two-fluid nozzle 3 in the fog generator 2.
The mist generated by the two-fluid nozzle 3 is rectified through a honeycomb wall 5 by a constant flow of compressed air sent from the air pipe 4, and is sent to the wind tunnel 1 at a constant speed.
sent inside.

[0011] With this experimental device, the radius of the mist droplets is 5 to 2.
Experiments were conducted with a mist of 0 μm and a mist amount in the range of 0.05 to 1.5 g/m 3 and the following results were obtained. This range of conditions makes it possible to reproduce all types of fog in natural conditions, from radiation fog and gliding fog, which have small fog particles and a small amount of fog water, to sea fog, which has large fog particles and a large amount of fog water.

When a semiconductor laser 6 with a wavelength of 780 nm was installed at one end of the wind tunnel 1 and irradiated, a red straight line was visualized in the fog. The brightness of this straight line is sufficient for the pilot to know the direction of travel in fog. Furthermore, in order to investigate the intensity of the laser beam, a photocell 7 was placed on the leeward side of the wind tunnel 1.
was placed. As a result of comparing the output of the photocell 7 with and without fog, the attenuation of the laser light was 10% or less at a distance of 6 m. In other words, it is possible to guide the line of sight using laser light over a long distance.

[0013] Next, a polygon mirror was placed in the wind tunnel 1, and when a laser beam was irradiated onto it, a red light screen was created. This shows that it is possible to guide the line of sight not only by straight lines but also by light curtains.

[0014] If this laser light is irradiated, for example, along the shoulders on both sides of the road, the optical axis of the laser light will be made visible and the driver of the car will be able to see the outline of the road even in dense fog. Therefore, the driver can drive even in dense fog by driving along the visualized optical axis. Similarly, if a laser irradiation device is placed along the approach path, taxiway, and apron near the landing point of an airfield runway, along the direction of aircraft movement, aircraft landing in dense fog can be directed to a visible optical axis. If a laser beam irradiation device is installed along the berth of a ship, it becomes possible to guide the line of sight of a ship in fog. Since the operator knows the direction of travel from the visualized optical axis, there is less danger than fogging using a carbon dioxide laser.

Furthermore, although the above embodiments are examples of use on roads, airports, and ports, the line-of-sight guidance method according to the present invention can be widely used not only on roads, airports, and ports.

[0016]

[Effects of the Invention] The present invention irradiates a laser beam into fog, and by reflecting and scattering the laser beam on the fog particles, the optical axis of the laser beam is visualized, making it possible to guide the line of sight of the operator of a car or aircraft. As a result, it has become possible to drive cars and guide aircraft to land even in dense fog, and has the excellent effect of preventing traffic obstructions caused by fog.

[0017] Furthermore, by using the method in combination with a fogging method using warm air jetting, the influence of wind on the fogging effect can be eliminated, so that the cost of fogging can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an experimental apparatus of the present invention.

[Explanation of symbols]

1……Wind tunnel 2... Fog generator, 3...2 fluid nozzle, 4...Air pipe, 5……honeycomb wall, 6... Laser light irradiation device, 7...Photocell.

Claims (4)

[Claims] Claim 1: A laser beam irradiation device is installed at the main part of a road, airport, or port, and when fog occurs, the laser beam is irradiated and reflected and scattered by the fog particles, and the laser beam axis is visualized. and a line-of-sight guidance method in fog, characterized by making it possible to guide the line-of-sight of a ship. 2. The method according to claim 1, wherein a laser beam irradiation device is arranged along the traveling direction of a car or aircraft on a road or an airport to guide the car or aircraft. Eye guidance method. 3. The line-of-sight guidance method in fog according to claim 1, wherein a laser beam irradiation device is arranged along the route to guide the ship. 4. A line-of-sight guidance method in fog, characterized in that line-of-sight guidance is performed by combining a line-of-sight guidance method using laser light and a method of artificially dissipating fog.