JP2000002533A - Laser clinometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an inclination with precision with a relatively simple and low-priced structure. SOLUTION: This embodiment comprises a liquid container 5 for retaining a liquid; semiconductor lasers 1, 2, 3 which are fitted facing a liquid face side in this liquid container 5 for irradiating laser beams to this liquid face side and receiving reflected beams of these irradiated beams; and display parts 16, 18 for displaying an intensity of returned beams of the laser beams received by the semiconductor lasers 1, 2, 3. Moreover, as shown in the drawing, the semiconductor lasers 1, 2, 3 and the liquid container 5 are disposed at a position where a liquid face is perpendicular to the laser beams when this liquid container 5 is horizontally positioned. And, an inclination supporting part 12 for supporting the liquid container 5 so as to incline freely is provided together with the liquid container 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser inclinometer, and more particularly to a laser inclinometer for measuring a tilt of a measurement surface using a semiconductor laser which oscillates laser light and receives return light.

[0002]

2. Description of the Related Art Conventionally, the movement of bubbles in a liquid has been used to measure the inclination of a measurement surface. There are also inclinometers using a cantilever and a piezoelectric ceramic, and inclinometers that irradiate light from below a container containing two kinds of media having different refractive indexes and detect a change in a light receiving position.

[0003]

However, in the above-mentioned conventional system using bubbles in liquid, there is a disadvantage that the accuracy of tilt measurement is affected by the accuracy of bubble position detection and the straightness of the bubbles themselves. there were. In addition, in the method using the cantilever or the pendulum, there is an inconvenience that the inclination measurement accuracy is influenced by the followability to the inclination of the cantilever or the pendulum and the position detection accuracy. In the method of irradiating a container filled with two types of media with light and capturing a change in the light receiving position, the accuracy of the tilt measurement is affected by the detection accuracy of the light receiving position, and the optical system such as a lens is expensive. There was an inconvenience.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser inclinometer capable of improving the inconvenience of the prior art, and in particular to providing a laser inclinometer capable of measuring the inclination with a relatively simple and inexpensive configuration and with high accuracy. And

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a liquid container for holding a liquid, a liquid container mounted to the liquid surface side of the liquid container, irradiating the liquid surface with laser light, And a display unit for displaying the intensity of return light of the laser light received by the semiconductor laser. In addition, the semiconductor laser and the liquid container are arranged at a position where the liquid surface and the laser beam are orthogonal to each other when the liquid container is positioned horizontally. And
The liquid container has a configuration in which an inclined support portion that supports the liquid container so as to be inclined is provided in addition. This aims to achieve the above-mentioned object.

When the laser inclinometer is installed on the measurement surface,
The inclined support portion is inclined along the inclination of the measurement surface. Then, the liquid container and the semiconductor laser attached thereto are also inclined. On the other hand, the liquid level is horizontal. When the liquid surface is horizontal while the liquid container is inclined, the semiconductor laser and the liquid container are arranged at a position where the liquid surface and the laser beam are orthogonal to each other when the liquid container is positioned horizontally. An inclination of the same angle as the inclination of the measurement surface occurs between the liquid surface and the irradiation direction of the laser beam. Here, the semiconductor laser receives the reflected light of the irradiation light. At this time, if the irradiation angle of the laser light with respect to the liquid surface is large, the intensity of the return light decreases. On the other hand, when the irradiation angle of the laser light with respect to the liquid surface is small, the intensity of the return light increases. Therefore, when the display unit displays the intensity of the return light of the laser light received by the semiconductor laser, the user can know the magnitude of the inclination of the liquid container with respect to the horizontal plane. And
When the user adjusts the inclination of the liquid container so that the display on the display unit is maximized, the angle between the irradiation direction of the laser beam and the liquid surface approaches orthogonally with the inclination of the liquid container. Then, when the inclination of the liquid container when the display on the display unit is maximized is measured, for example, a scale is attached to the liquid container, and by reading this, the inclination angle of the measurement surface can be known.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a laser inclinometer according to the present invention. The laser inclinometer includes a liquid container 5 for holding a liquid, and a semiconductor laser attached to a liquid surface side of the liquid container 5 for irradiating the liquid surface with laser light and receiving reflected light of the irradiated light. 1,2,3
And display sections 16 and 18 for displaying the intensity of the return light of the laser light received by the semiconductor lasers 1, 2 and 3. Moreover, as shown in FIG.
3 and the liquid container 5 are arranged at positions where the liquid surface and the laser beam are orthogonal to each other when the liquid container 5 is located horizontally. Further, the liquid container 5 is provided with an inclined support portion 12 for supporting the liquid container 5 so as to be able to freely tilt.

In the example shown in FIG. 1, the liquid container 5 has a spherical shape. This liquid container 5 holds a liquid 7 having low viscosity. The reflection plate 9 floats on the liquid surface 11 of the liquid 7. The reflecting plate 9 is tiltably supported by a reflecting plate supporting member 10 fixed to a lower portion of the spherical liquid container 5. For this reason, the reflection plate 9 is held on the same plane as the liquid surface 11 regardless of the inclination of the liquid container 5.

Here, the liquid container 5 contains an opaque and low-viscosity liquid up to the center level. The color of the liquid is
For example, the color may be milky white or any color that can reflect laser light on the liquid surface. Float a liquid that causes confusion, such as a plastic plate, to measure the liquid level,
Distance measurement is performed at two places to obtain a difference in inclination from the horizontal state in the XY directions.

In the example shown in FIG. 1, three laser elements 1 to 3 are provided as a semiconductor laser. Here, when the XY orthogonal coordinates are defined on a horizontal plane and the Z axis is defined in a direction orthogonal to this plane, the inclination about the X axis and the inclination about the Y axis are measured. Therefore, first, the first and second laser elements are arranged on the X axis and the Y axis, respectively, which are orthogonal at the center of the tilt.

As shown in FIG. 2, the reflection plate is floated on the liquid surface 11 at a position where the laser light emitted from the first and second laser elements 1 and 2 is reflected. In the present embodiment, the laser light of the third laser element 3 is
It is reflected by the liquid surface 11 of the liquid 7 inside.

As shown in FIG. 3, the liquid container 5 is supported by an inclined support portion 12 so as to be freely inclined in the X axis and the Y axis. And, on the outer peripheral surface of the spherical liquid container, scales 22 indicating the magnitude of the inclination are provided on the X axis and the Y axis. Since the liquid container 5 is tiltable with respect to the tilt support portion 12, the user can tilt the liquid container 5 freely. The magnitude of the tilt of the liquid container tilted by the user can be read on the scale 22. The display unit shown in FIG. 1 guides the user to tilt the liquid container.

FIG. 4 is an explanatory diagram showing the positional relationship between the first to third laser elements, and corresponds to the diagram shown in FIG.
The first laser and the second laser are positioned on the X-axis and the Y-axis of the orthogonal coordinates of the plane parallel to the horizontal plane when the liquid container 5 is horizontal. The center of the rectangular coordinates is the center of the inclination of the liquid container, as shown in FIG. Then, in order to eliminate the need for special calculations, the positions of the first and second laser elements are each equidistant from the center. When the liquid container is not made spherical but has another special shape, the positions of the first and second laser elements do not necessarily have to be equidistant from the center. In this case, it is preferable to amplify the value of the signal in accordance with the difference in distance so that the level display on the display unit is uniform.

FIG. 5 is a diagram showing the positional relationship between the first and second laser elements. In the figure, a solid line indicated by reference numeral 28 is a part of a reference plane. And the liquid container is denoted by reference numeral 2.
As shown in FIG. 6, when the inclination of the first laser beam is inclined downward to the right on the ZX plane about the center line of the Y axis indicated by 4, the distance between the first laser beam and the second laser element becomes the reference. The distance from the plane becomes shorter. Further, X indicated by reference numeral 26 in FIG.
When the liquid container is inclined downward and to the right on the ZY plane having the origin on the left side with respect to the center line of the axis, the distance between the second laser element and the reference plane decreases as shown in FIG. .

As shown in FIGS. 5 and 6, the first and second
When the laser element is positioned on the X-axis and Y-axis lines of the orthogonal coordinate system with the center of the inclination as the center, the inclination at the ZX coordinate can be measured by the first laser element, and the ZY coordinate can be measured. Can be measured by the second laser element. Therefore, when the display unit displays the magnitude of the distance according to the return light received by the first and second laser elements, it is possible to display the degree of inclination on the X axis and the Y axis.

This can be realized by using a self-mixing type laser Doppler distance meter. In this case, return light and oscillation light are self-mixed by the laser element (resonator). When the self-mixed light is received by the photodiode, a beat wave is obtained. Since the wavelength of the beat wave indicates the distance to the liquid surface, if the display on the display unit is changed according to the change in the wavelength, the degree of inclination on the X axis and the Y axis can be displayed. In this case, as shown in FIG.
When the liquid container 5 is inclined with respect to the center 24 of the axis, the distance between the first laser element 1 and the reference plane 28 does not change, and the distance between the second laser element 2 and the reference plane 28 changes. I do. Therefore, when the display based on the return light of the first laser element 1 and the display based on the return light of the second laser element 2 are performed separately, for example, as shown in FIG. When connected to the element and displayed, the first level gauge 18 indicates the degree of inclination on the X axis, and the second level gauge 16 indicates the degree of inclination on the Y axis.

Next, the reflection of laser light will be discussed.
FIG. 8 is an explanatory diagram showing a state of reflection of the laser beam applied to the reflection plate. As shown in FIG. 8, the reflection plate 9 in the present embodiment irregularly reflects the laser light. Therefore, the relationship between the return light to the laser element and the inclination angle of the laser element is shown in FIG.
It becomes as shown in. On the other hand, when the liquid surface 11 is irradiated with laser light, the liquid surface reflects specularly, so that the reflected light does not return to the laser element in the state shown in FIG.

FIG. 11 shows the distribution of the output level of the return light for each inclination angle. As shown in FIG. 11, when the laser light is reflected by the liquid surface 11, the reflected light does not return unless the liquid surface 11 and the laser element 3 are perpendicular. Therefore, FIG.
As shown in the figure, the laser element 3 and the LED 14 are connected,
If the LED 14 is turned on when return light is generated in the laser element 3, the LED 14 is turned on when the liquid container 5 fixed to the laser element becomes horizontal with the liquid surface 11. In this case, from the state where the inclination is large, this LE
Adjustment until the lighting of D14 becomes difficult. Therefore, the first
When the distance to each liquid level is measured using the second laser element and displayed on the level gauge shown in FIG. 1, the degree of inclination of each of the X-axis and Y-axis can be displayed to the user. .

By utilizing the irregular reflection shown in FIGS. 8 and 9, the level gauge can be displayed on the level gauge without measuring the distance to the liquid surface. That is,
As shown in FIG. 12, first, the laser inclinometer according to the present embodiment is installed on the measurement surface 20 where the inclination is to be measured. Then, the liquid container and the semiconductor laser attached thereto are inclined in the same manner as the inclination of the measurement surface. On the other hand, since the low-viscosity liquid is kept horizontal, the liquid container 5 and the semiconductor laser and the liquid surface are inclined at the same angle as the inclination angle of the measurement surface 20, as shown in FIG. Then, the return light decreases and the level gauge displays a small value. The user tilts the liquid container 5 so as to be horizontal, depending on the display of the level gauge. Then, when the intensity of the return light of the laser beam becomes maximum, the liquid container 5 becomes horizontal as shown in FIG. Then, the inclination angle of the liquid container 5 at this time is the inclination angle of the measurement surface.

In the examples shown in FIGS. 10 to 13, the semiconductor laser includes a laser element 1A and a condenser lens 1B. In a preferred embodiment, the laser element includes a laser diode that outputs laser light in accordance with a laser drive current, and a photodiode that receives light self-mixed with return light in a resonator of the laser diode. I have. If the laser drive current is a triangular wave, a sawtooth wave is added to the triangular wave. Since the wavelength of the sawtooth wave indicates the distance to the liquid surface, when the signal processing units 15 and 17 analyze the wavelength of the sawtooth wave, the distances in the X axis and the Y axis can be measured. .

Further, if a band-pass filter for canceling a triangular wave component from the output of the photodiode and passing only a predetermined wavelength is provided, the intensity of the return light can be displayed in real time without performing any special signal processing. can do. That is, assuming that the frequency of the sawtooth wave passed through the bandpass filter is a frequency corresponding to the distance when the liquid container 5 is horizontal, the display of the level gauge changes according to the change in the distance from the measurement surface. . That is,
Due to the action of the band-pass filter, as the inclination of the liquid container 5 increases, the frequency of the sawtooth wave changes, making it difficult to pass through the band-pass filter, thereby reducing the level gauge display. On the other hand, when the liquid container 5 approaches horizontal, the saw-tooth wave frequency approaches a predetermined frequency, and the signal passing through the band-pass filter increases, whereby the display of the level gauge increases.

Referring again to FIG. 1, the first and second laser elements are disposed on respective straight lines orthogonal to each other when the center of the inclination of the liquid container is set as the origin. Therefore, the change in the distance directly indicates the inclination. Further, as shown in FIG. 3, the inclined scale is provided along the outer circumference of the sphere connecting two points where the diameter of the sphere along the laser irradiation direction and the sphere intersect. When the inclined scales are provided on the X side and the Y side, the liquid container 5 can be easily inclined to be horizontal.

When a laser beam is emitted from the laser elements 1, 2, 3, the reflecting plate 9 irregularly reflects the emitted laser beam. Then, even if the liquid container 5 is tilted and the incident angle of the laser beam becomes larger than 0 degree, the reflected light returns to each of the laser elements 1 and 2 due to the irregular reflection. The intensity of this return light decreases as the incident angle increases. Therefore, as the incident angle increases, the value of the display on the display units 16 and 18 decreases, and as the distance changes, the sawtooth wave frequency changes and the values on the display units 16 and 18 change.

The user tilts the liquid container 5 so as to increase the value of this display. Due to this inclination, the liquid container 5
When the angle of the liquid container 5 approaches horizontal, the value displayed on the display units 16 and 18 increases. On the other hand, when the angle of the liquid container 5 moves away from horizontal, the value displayed on the display units 16 and 18 decreases. By controlling the inclination of the liquid container 5, each of the display units 16, 18 is controlled.
After the display becomes maximum, fine adjustment of the inclination is performed. For the fine adjustment of the inclination, a third laser element and an LED (lighting device) are used.

There is a difference in the output level distribution between the case where the laser beam is confused and the case where the laser beam is specularly reflected. In the third set of semiconductor lasers, return light cannot be obtained unless laser light is applied substantially perpendicular to the liquid surface. When the return light of the third set of semiconductor lasers is detected and the LED is made to emit light, the state is perpendicular to the water surface, and the difference between the inclination and the measurement point can be displayed based on this state.

The liquid container 5 does not necessarily need to have a spherical shape, but may have a shape shown in FIGS. 14 and 15 as long as it has a portion for fixing the liquid surface and the semiconductor laser and a portion for adjusting and measuring the angle.

In this example, the liquid container 5 includes the first and second liquid containers.
A first liquid reservoir 43 to which the first and second laser elements 1 and 2 are attached and which has a reflection plate; a second liquid reservoir 41 to which the third laser element 3 is attached; Flow paths 45 and 47 for mutually moving the liquid held in the first liquid storage portion;
Of the liquid reservoirs 41, 43 are integrally and tiltably supported. Moreover,
The first or second liquid reservoirs 41 and 43 are provided with the first
Alternatively, an inclination measuring device 53 for measuring the inclination of the second liquid reservoirs 41 and 43 is also provided. The inclination measuring device 53 includes, for example, a circular main scale and a vernier scale.

Next, the configuration of the display control system will be described with reference to FIGS. This corresponds to the example shown in FIG.
4 is common to the examples shown in FIG. As shown in FIG. 16, the laser element is driven by a drive current modulated by a laser diode drive current modulation circuit 19. For example, when a triangular wave is used as in the LD drive current shown in FIG. 17A, the sawtooth wave self-mixes according to the distance to the liquid surface.
When this is received by the photodiode, the photodiode outputs a PD output current shown in FIG. When this PD output current is passed through the filters / amplifiers 15A and 17A, a beat wave (sawtooth wave) shown in FIG. 17C is obtained. Then, the magnitude of the amplitude of the sawtooth wave is displayed via band-pass filters 15B and 17B in which the frequency band to be passed is determined in advance. Assuming that the predetermined frequency is a sawtooth wave frequency when the liquid container 5 is horizontal, when the distance between the laser element and the liquid surface changes as shown in FIG. 5 due to the inclination of the liquid container, the sawtooth wave frequency changes. Changes, it becomes difficult to pass through the bandpass filter,
The displayed value decreases. By utilizing this, the degree of inclination of the liquid container can be displayed in real time without requiring special signal processing.

As described above, according to the present embodiment, the vertical state (horizontal state) with respect to the liquid surface can be accurately determined using the directivity of the laser beam. Furthermore, since the degree of inclination is displayed using the output change of the laser range finder, the user can easily obtain the vertical state (horizontal state). In addition, since the configurations of the optical system and the electronic circuit for light emission and light reception can be relatively simplified, the inclinometer can be manufactured relatively inexpensively in relation to the accuracy to be achieved.

[0031]

Since the present invention is constructed and functions as described above, according to the present invention, the semiconductor laser and the liquid container are positioned at a position where the liquid surface and the laser beam are orthogonal to each other when the liquid container is positioned horizontally. Therefore, if there is an inclination of the same angle as the inclination of the measurement surface between the liquid surface and the irradiation direction of the laser light, the intensity of the return light of the laser light changes according to the magnitude of the inclination, and therefore, The user can know the magnitude of the inclination of the liquid container with respect to the horizontal plane, and know the inclination angle of the measurement surface by measuring the inclination of the liquid container with respect to the inclination support part when the display on the display unit is maximized. This makes it possible to measure the inclination of the measurement surface using a semiconductor laser, and it is possible to measure the inclination with high accuracy with a relatively simple and inexpensive configuration, which is an unprecedented superiority. Laser inclinometer It is possible to provide.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a front view of the laser inclinometer shown in FIG. 1;

FIG. 4 is a diagram showing a positional relationship of the semiconductor laser shown in FIG.

FIG. 5 is an explanatory diagram showing an example of a change in a distance from a laser element to a liquid surface due to a tilt of a liquid container.

FIG. 6 is an explanatory diagram showing ZX coordinates in the example shown in FIG. 5;

FIG. 7 is an explanatory diagram showing ZY coordinates in the example shown in FIG. 5;

FIG. 8 is an explanatory diagram showing an example of irregular reflection on the reflector shown in FIG. 1;

FIG. 9 is a graph showing a change in output level in the example shown in FIG.

FIG. 10 is an explanatory diagram showing an example of specular reflection on the liquid surface shown in FIG.

FIG. 11 is a graph showing a change in output level in the example shown in FIG. 11;

FIG. 12 is an explanatory diagram showing a relationship between a tilt of a measurement surface and a liquid surface.

FIG. 13 is an explanatory view showing an example in which the liquid container is inclined to the horizontal on the measurement surface shown in FIG.

FIG. 14 is a plan view showing another example of the liquid container.

FIG. 15 is a diagram showing a side surface of the laser inclinometer shown in FIG. 14;

FIG. 16 is a block diagram showing a configuration of a display control system of the laser inclinometer shown in FIG. 1 or FIG.

17 is an explanatory diagram showing an example of a signal handled by each component shown in FIG. 16; FIG. 17 (A) is a diagram showing an example of an LD drive current; FIG. 17 (B) is an example of a PD output current; In the diagram showing
FIG. 17C is a diagram illustrating an example of a beat wave (sawtooth wave).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st laser element 2 2nd laser element 3 3rd laser element 5 Liquid container 7 Liquid 11 Liquid level 14 LED (lighting device) 16, 18 Level gauge (display part)

Claims (7)

[Claims] 1. A liquid container for holding a liquid, a semiconductor laser attached to a liquid surface side in the liquid container, irradiating the liquid surface with laser light and receiving reflected light of the irradiation light, A display unit for displaying a state of the laser light received by the semiconductor laser, wherein the liquid surface and the laser light are orthogonal to each other when the semiconductor laser and the liquid container are positioned horizontally. A laser inclinometer, which is disposed at a position, and the liquid container is provided with a tilt support portion for supporting the liquid container in a tiltable manner. 2. The laser inclinometer according to claim 1, wherein the liquid container has a tilt scale for displaying a tilt angle with respect to the tilt support portion. 3. A liquid container for holding a liquid, a semiconductor laser attached to the liquid surface of the liquid container, irradiating the liquid surface with laser light and receiving reflected light of the irradiated light, and a semiconductor laser. A display unit that displays a change in distance between each semiconductor laser and the liquid surface based on the laser light received by the semiconductor laser, and a tilt support unit that supports a tilting operation of the liquid container. When the liquid container is located horizontally, the liquid container is arranged at a position where the liquid surface and the laser beam are orthogonal to each other, and the liquid container floats on the liquid surface and follows the inclination of the liquid surface. A reflecting plate that is inclined with respect to the liquid container and irregularly reflects the laser light, wherein the semiconductor laser irradiates the reflecting plate with laser light and receives reflected light from the reflecting plate. And a second laser element, and a third laser element that irradiates the liquid surface with laser light and receives light reflected from the liquid surface, wherein the display unit includes the first and second lasers. A plurality of level gauges that indicate the magnitude of a signal that has passed through a predetermined frequency band out of the laser light emitted from the element to the liquid surface side, and when there is return light from the third laser element A laser inclinometer comprising a lighting device for lighting. 4. The laser tilt according to claim 3, wherein the first and second laser elements are arranged on respective straight lines orthogonal to each other when the center of the tilt of the liquid container is set as an origin. Total. 5. The liquid container is a sphere having a scale indicating an angle of inclination, and the scale connects the sphere with a diameter of the sphere along an irradiation direction of the laser and two points where the sphere intersects. The laser inclinometer according to claim 3, wherein the laser inclinometer is provided along the outer circumference of the laser inclinometer. 6. The liquid container according to claim 5, wherein the liquid container includes a reflector supporting member fixed to a lower portion of the liquid container and having a conical vertex for supporting the reflector. Laser inclinometer. 7. The liquid container, wherein the first and second laser elements are mounted and a first liquid reservoir having the reflection plate, and a second liquid to which the third laser element is mounted. A reservoir, a flow path for mutually moving the liquid held in the second liquid reservoir and the first liquid reservoir, and the first and second liquid reservoirs are integrated and tiltable. And a tilt measuring device for measuring the tilt of the first or second liquid reservoir is provided in one of the first and second liquid reservoirs. The laser inclinometer according to claim 3.