JPH01113687A - Optical measuring apparatus of altitude of cloud - Google Patents

Abstract

PURPOSE:To prevent the incident of the sunlight and the sticking of rain or snow, by a construction wherein the optical axes of a projector and a photosensor are inclined with respect to the vertical direction and a hood covering the transparent window planes of a projection plane and a photosensing plane so that they can not be seen vertically from above is provided at a position not intersecting the optical axes. CONSTITUTION:The optical axis (a) of a projector 1 is inclined by an angle theta1 from the vertical direction, while the plane of a transparent window 103 is also inclined by theta1 with respect to the horizontal direction. A photosensor 2 is disposed in the same state as the projector 1. Next, a slanting hood 3 is provided above the projector 1 and the photosensor 2, and an angle theta2 of inclination of the hood is set so that it does not intersect the optical axis (a). Besides, the upward length of the hood 3 is set so that the whole of transparent windows 103 and 203 are covered with the hood when viewed from above. Since the optical axis (a) is inclined by the angle theta1 in this way, measurement can be made in the direction wherein the sunlight is not incident directly, and the sticking of rain or snow or others on the transparent windows can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cloud height measuring device (so-called,
The present invention relates to a ceilometer (ceilometer), and particularly to an optical cloud height measuring device that uses light (for example, laser light) as a measuring medium in the summer.

[Prior art]

2. Description of the Related Art Optical cloud height measurement devices are known that receive reflected light from clouds of light emitted toward the sky, measure the time from the emission of light to reception, and measure the height of the cloud from the time.

In conventional optical cloud height measurement devices, the light is emitted vertically upward, so the optical axes of the emitter and receiver are set vertically upward, and the light emitting surface of the emitter and the light receiving surface of the receiver are set vertically upward. is horizontal.

In addition, in order to prevent sunlight from directly entering the emitter and light receiver and damaging the light emitting and light receiving elements, a long cylindrical hood should be attached to the light emitter and light receiver, or a mechanical shutter should be installed. , preventing sunlight from entering the above-mentioned projector and receiver. In particular, cloud height measurement devices installed in high latitude regions always require such sunlight blocking means because the sun's orbit is high.

[Problem that the invention seeks to solve]

Rain or snow easily adheres to the transparent window surface (usually crown glass is used) installed in the area (when it starts to rain or snow, the strength of the light emitting and receiving light decreases, making it possible to measure cloud height. Altitude decreases rapidly.

In addition, especially for those equipped with a mechanical shutter, when sunlight enters the light emitting/receiving field of view, the mechanical shutter closes and observation must be interrupted, and if the mechanical shutter malfunctions, the light emitting element and light receiving element may become damaged. (The light-emitting element and the light-receiving element are fixed at the focal point of the optical lens of the emitter and receiver, and the focus of the incident sunlight is at the point of the light-emitting element and the light-receiving element.) ) 0 In addition, for those with a cylindrical hood, especially those installed in high latitude areas, the cylindrical hood must be extremely long, making the measurement field of view narrow and making practical measurements difficult. It becomes impossible.

The present invention proposes to solve the above problems.

[Means for solving problems]

In order to solve the above problems, the present invention sets the optical axes of the projector and the receiver of the optical cloud height measurement device in an inclined direction with respect to the vertical direction, and furthermore, the light emitting surface of the projector is and a hood is provided at a position where the light-transmitting window surface provided on the light-receiving surface of the light receiver is hidden when viewed vertically from above and does not intersect with the optical axis, and further, the light-transmitting window surface is hidden from the above-mentioned optical axis. The angle is set so as to be inclined by an angle in the vicinity of the Brewster angle, including the Brewster angle, with respect to a direction perpendicular to the Brewster angle.

[Effect]

Since the light-transmitting window surfaces of the projector and receiver are inclined, direct sunlight can be avoided by installing the cloud height measuring device with the optical axis directed in the opposite direction of the sun's orbit.

In addition, especially for cloud height measurement devices installed in high latitude areas, direct sunlight can be completely prevented from entering by the presence of a hood and/or by the inclination of the transmitting/receiving light-transmitting surface at an angle near the Prusster's angle. be able to.

In addition, since the transparent window surfaces of the emitter and receiver are entirely covered with a hood when viewed from vertically above, there is no layer of rain or snow from above, and even if rain or snow does not form from the side. Even if there is adhesion, it will flow due to the slope of the translucent window surface (if the slope of the angle near Brewster's angle is added to the percentage, the accumulated rain and snow will flow even more easily), and as a result, the rain and snow will flow. There is very little adhesion, and there is very little decrease in measurable cloud height.

[Embodiments of the invention]

FIG. 1 is a front view of the light emitting and receiving part of an optical cloud height measuring device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is another embodiment. The A-Alfr plane view in FIG. 1 and FIG. 4 are diagrams for explaining the relationship between the incident angle of light and the reflectance of light.

As shown in FIG. 1, in the light emitting/receiving section of the embodiment, a light emitter 1 and a light receiver 2 are arranged side by side, and the light (laser light in the embodiment) emitted from the light emitter 1 is reflected by a cloud into the light receiver 2. It is designed to be captured by

Further, as shown in FIG. 2, a light emitting element (for example, a laser element) 101 and an electronic circuit 102 such as a drive section of the light emitting element 101 are housed inside the floodlight 1, and the floodlight is made of, for example, crown glass. A transparent window 103 is fitted therein.

This light projector 10 light ma is at an angle θ from the vertical direction.

(for example, 20 degrees in the embodiment), and therefore the translucent window 103 is set at the above angle θ! with respect to the horizontal direction. (It is assumed that the surface of the transparent window 103 is set in a direction perpendicular to the optical axis a.)

The structure of the light receiver 2 is the same as that of the light projector 1 except that a light receiving element is housed in place of the light emitting element 101, and the optical axis is also tilted at the angle θI, so that the light receiving surface is transparent. The optical window 203 is also slightly inclined at an angle θ.

At the top of the emitter 1 and receiver 2 described above, an inclined 7-door 3 is provided, and its inclination angle θ is set at an angle such that the tip 301 does not intersect with the optical axis a. The upward length is the length of both transparent windows 103 when viewed from vertically above.
, 203 is set to a length that is entirely covered by the hood. By doing so, the projection or reception of light is not obstructed by the 7-door 3.

As described above, since the light 1141Ia is tilted by the angle θ, the light 1141Ia is directed toward the floodlight 1 so that sunlight does not directly enter the light source 1.
The cloud height measuring device can be installed with the light receiver 2 facing. In addition, even if there is no 7-dore 3, the light I
11] Due to the slope of a, sunlight bfJ'' - light emitting element 101
(or the light-receiving element). That is, for example, the setting of the inclination angle θ8 of the surfaces of the light-transmitting windows 103 and 203 (the larger this angle is, the wider the area where direct sunlight is not incident) or the setting of the light emitting element 10
This is possible by setting the distance between 1 and the light-receiving element and the light-transmitting windows 103, 203 (the longer this distance, the wider the area where direct sunlight is not incident).

In addition, when it rains or snows, the rain and snow from vertically above are blocked by the 7-door 3 and the translucent windows 103, 203
Rain and snow from the side (usually less than rain and snow from vertically upwards) are sometimes layered on the translucent windows 103, 203.
Even if a layer is applied to the transparent window 103, 203, most of the layer is not applied because it flows down along the slope of the transparent window 103, 203.

Although not shown in the figure, the light emitting surface of the light emitter 1 and the light receiving surface of the light receiver 2 (light transmitting windows 103 and 203) are heated by heaters in winter, and the light transmitting windows 103 and 20
The snow layered on 3 melts and flows down.

Next, another embodiment will be explained with reference to FIG. That is, in this embodiment, the light-transmitting windows 103 and 20 of the emitter 1 and the receiver 2 are
3 at an angle θ2 from the direction orthogonal to the light I+11 a.
The translucent windows 103, 203 are tilted by
The angle of inclination of the plane from the horizontal direction is θ1101J, which is a larger inclination than that of the previous embodiment.

In the case of this embodiment, since the direction of the optical axis a, that is, the direction of incidence of light, is not perpendicular to the planes of the light-transmitting windows 103 and 203, reflection of light at the light windows 103 and 203 is a problem. becomes. That is, if there is a lot of reflection, the amount of light projected from the light emitter 1 and the amount of light received by the light receiver 2 will decrease, and the altitude at which cloud height can be measured will decrease.

Incidentally, the relationship between the angle of incidence of light (Pi) of a specific polarization plane onto a transparent body and the reflection of the light on the transparent body shows a tendency as shown in FIG. In other words, as the angle of incidence of light (the angle from the vertical angle placed in the translucent curve) increases, the reflectance gradually increases, but after a certain angle, the reflectance begins to decrease again. , after reaching a minimum characteristic, the reflectance suddenly rises again, and the reflectance is 100% (state of total reflection).
becomes. This characteristic is a well-known characteristic, and the angle θa at which the P-wave polarization plane reflectance becomes minimum is taken as the Brewster angle, and the angle θb at which total reflection occurs is the critical angle. The Brewster angle θa and the critical angle θb have different values depending on the refractive index of the transparent body.

Considering the reflection characteristics described above, in the embodiment shown in FIG. 3, the angle θ is set near the Brewster angle θa, which reduces reflection on the transparent window surface when transmitting or receiving light. It's like this. Ideally, this angle θ should be set to the Brewster's angle θa, but when set in this way, if the angle θ deviates in the direction of increasing, it will suddenly become a state of total reflection and the measurement will fail. ``T If@'', so in the embodiment, the angle θ is set near the Brewster angle θa (near the direction in which the angle becomes smaller).

Further, in the white plate glass (crown glass) used in the transparent windows 103 and 203 in the example, the Brewster angle θa was about 33 degrees, and the angle θ was set at 30 degrees in the example. Therefore, by adding the inclination angle (20v) of the light beam a,
The surface of the transparent window 103.203 has an inclination of 50 degrees from the horizontal direction.

Because the translucent windows 103 and 203 are thick (and slanted) in this way, in the embodiment shown in FIG. However, depending on the measurement area, the hood 3 may not be necessary, since rain and snow adhering to the surfaces of the translucent windows 103 and 203 will run off more quickly during rain or snowfall (if there is no hood 3). There is also.

In addition, when the hood 3 is provided, by creating an air flow of about 41-degrees outward from the inside of the hood 3 (in Fig. 3, the proa is connected to the hole 4 provided in the pace). This is more effective as it eliminates the rain and snow blown into the hood 3 (rain and snow from the direction of the beak).

〔Effect of the invention〕

As is clear from the above description, the present invention has the following various advantages, and the present invention has extremely significant effects.

Since the optical axes of the emitter and receiver are set in an inclined direction, direct sunlight can be avoided by considering the installation direction of the cloud height measurement device, and it is possible to avoid direct sunlight from entering the sky by considering the installation direction of the cloud height measuring device. No special mechanism is required.

CB) Direct incidence of sunlight can be avoided in high latitude areas by using a hood that hides the translucent windows of the emitter and receiver when viewed from vertically above, and is recessed at a position that does not intersect the optical axis.

(0) The above-mentioned step 7 prevents rain and snow from adhering to the transparent window from vertically above, and since the surface of the transparent window is inclined, for example, rain and snow from the horizontal direction can be prevented from adhering to the transparent window. Even if it adheres to the optical window, it quickly washes off, so it is possible to prevent light transmission obstruction without using a complicated mechanism such as a wiper, and there is little decrease in the measurable cloud height.

■) By further tilting the transparent window surfaces of the emitter and receiver by an angle close to the Brisister angle, the effect of item (C) above becomes even more pronounced, and the direct water irradiation of sunlight is also reduced. Depending on the installation location of the 1% measuring device, this problem can be avoided with only the above configuration, which simplifies the configuration of the measuring device.

■ Also, as a secondary effect of providing the above hood, the upper part of the hood does not have a structure that is open directly to the sky. In the summer, heat radiation to the inside of the emitter and receiver is greatly reduced, making it less likely that equipment failure will occur.In the winter, the heater for heating the translucent surface (
The heat efficiency of heaters installed for snow melting improves.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Fig. 3 is a cross-sectional view taken along the line A-A in Fig. 1 of another embodiment. , FIG. 4 is a diagram illustrating the relationship between the incident angle of light and the reflectance. 1... Emitter 2... Receiver 3... Hood 103.203... Transparent window 〇Figure 3Figure 2

Claims (1)

[Scope of Claims] 1. The optical axes of the emitter and receiver are set in an inclined direction, and the transparent window surfaces provided on the light emitting surface of the emitter and the light receiving surface of the light receiver are hidden when viewed from vertically above. , and an optical cloud height measuring device provided with a hood at a position that does not intersect the optical axis. 2. The optical axes of the emitter and receiver are set in an inclined direction, and the light-transmitting window surfaces provided on the light-emitting surface of the emitter and the light-receiving surface of the receiver are at Brewster's angle with respect to the direction orthogonal to the optical axis. An optical cloud height measurement device that is tilted at an angle near the Brewster angle, including the Brewster angle.