JP3210450B2 - Tilt detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt detecting device used for surveying equipment, measuring equipment, etc., which measures a change in tilt amount or detects a tilt amount in order to correct the tilt of the equipment. Things.

[0002]

2. Description of the Related Art In order to measure how a reference plane of a surveying instrument, a measuring instrument, or the like is inclined with respect to a horizontal plane, it is necessary to detect inclination in at least two axes in the reference plane.

As a method of detecting the inclination of a reference surface of a surveying instrument, a measuring instrument, or the like, there is a method using a free liquid level.

In this method, a light beam is made incident on a free liquid surface, and the amount of change in the optical axis of the reflected light of the light beam is detected by a light receiver. When mercury or the like is used as a liquid having a free liquid surface, if a light beam is incident perpendicularly to the free liquid surface, a reflection angle having the same sensitivity to the inclination of the liquid surface is obtained in all two-dimensional directions. It is possible to detect the inclination of the reference plane.

However, in practice, liquids such as mercury described above are difficult to use in terms of cost and safety, and transparent liquids such as silicone oil are practically used. When a transparent liquid is used, total reflection is used, but since there is a critical angle between the liquid and air, in order to totally reflect the light beam on the free liquid surface, the incidence of the light beam on the free liquid surface is the critical angle. An incident angle θ corresponding to the angle is required. Thus, in the conventional tilt detecting device using the free liquid surface, a light beam is incident on the free liquid surface at a predetermined angle.

[0006] When a light beam is incident on the free liquid surface at a predetermined angle, the change in the reflection angle of the reflected light in two different axial directions with respect to the inclination of the liquid surface is not uniform.
Therefore, in the inclination detecting device using the free liquid level, a measure is taken against the non-uniformity of the change of the reflection angle.

One of the conventional tilt detecting devices is such that light beams having two different optical axes are incident on the free liquid surface at a predetermined angle, reflected light is received by a light receiver, and a change in the light receiving position of each light receiver. Thus, the inclination with respect to the two optical axes is detected, and the inclination of a reference plane such as a surveying instrument or a measuring instrument with respect to a horizontal plane is calculated from the detected inclination of the two optical axes.

[0008] As another conventional tilt detecting device utilizing a total reflection of the free liquid surface, a light beam having only one optical axis is made incident on the free liquid surface. The light beam is detected by the light receiver, and the two-axis direction of the light beam in the light receiver, that is, the amount of change in the light receiving position in the two directions of the optical axis direction of the light beam and the other axis direction is obtained. Some measuring instruments and the like determine the reference plane inclination. In the other conventional tilt detecting device, the sensitivity of the position change on the light receiving surface with respect to the change of the tilt differs in the two directions of the optical axis direction of the light beam and the other axis direction. ing.

[0009]

Among the conventional tilt detecting devices, the former has a disadvantage that the configuration of the device becomes complicated because the projection system of the light beam is two optical systems, and the conventional tilt detecting device has a disadvantage. In the latter device, the reflection angle of the light beam from the free liquid surface has a sensitivity difference in the two axial directions on the light receiving surface with respect to the amount of inclination of the free liquid surface. Electrical correction is required, and an electrical processing system for the correction must be separately provided, which causes a problem that the processing system becomes complicated.

In view of such circumstances, the present invention seeks to detect the inclination of the reference plane using only a one-axis optical system and without providing an electrical processing system for separate correction.

[0011]

According to the present invention, there is provided a liquid filling container in which a transparent liquid is filled so as to form a free liquid surface, and a luminous flux totally reflected at the free liquid surface at a predetermined angle to the free liquid surface. A light projecting system for projecting, a cylindrical lens system for dropping a light beam reflected on the free liquid surface, and a light receiver for receiving a reflected light beam transmitted through the cylindrical lens system,
The amount of inclination of the free liquid surface is detected at the light receiving position of the reflected light beam on the light receiving surface of the light receiver, and the uniformity of the temperature distribution with respect to the temperature change of the transparent liquid is further improved.

[0012]

The sensitivity of the change in the reflection angle when the angle of incidence of the light beam with respect to the free liquid surface changes relative to the free liquid surface depends on the inclination direction of the free liquid surface. This difference in sensitivity is optically corrected by a cylindrical lens system,
The amount of tilt of the free liquid surface can be measured without electrically correcting the detection result of the reflected light beam received by the light receiver.
Furthermore, if a temperature distribution is generated in the transparent liquid, the refractive index of the transparent liquid becomes non-uniform, causing refraction of the optical axis and the like, which affects the measurement result. However, by improving the uniformity of the temperature distribution of the transparent liquid, Stability and reliability of measurement against environmental temperature changes are improved.

[0013]

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

First, a light beam is incident on the free liquid surface at a predetermined angle, and when the light beam is totally reflected on the free liquid surface, the free liquid surface is inclined relative to the light beam. The difference in the sensitivity of the change of the reflection angle with respect to the inclination direction of the surface will be described with reference to FIGS.

Actually, the free liquid level is kept horizontal and the incident direction of the light beam changes. However, the following description is based on the assumption that the incident direction of the light beam is constant and the free liquid surface is inclined.

In FIG. 1, reference numeral 1 denotes a free liquid surface, and it is assumed that an incident light beam 2 is incident on the free liquid surface 1 at an angle θ. The free liquid level 1
And an xz coordinate plane formed by the coordinate axis x and the coordinate axis z substantially coincide with each other, and a coordinate axis perpendicular to the coordinate plane is defined as y. It is assumed that the optical axis of the incident light beam 2 exists in a coordinate plane formed by the coordinate axes z and y. From this state, if the free liquid surface 1 is inclined by an angle α about the coordinate axis x, the optical axis of the reflected light beam 3 moves in the yz coordinate plane, and the reflection angle changes by ξ1x in the yz coordinate plane. . In this case, the relationship between the liquid surface displacement angle α and the reflected displacement angle ξ1x is ξ1x =
2α, and in this case, the reflection displacement angle ξ2x in the xy coordinate plane does not occur. In the figure, reference numeral 14 denotes a mirror.

On the other hand, as shown in FIG. 2, if the free liquid surface 1 is inclined by an angle α about the coordinate axis z, the reflected light flux 3 separates from the xy coordinate plane and the yz coordinate plane, respectively. Move. Accordingly, a reflection displacement angle ξ1z and a reflection displacement angle ξ2z appear on the xy coordinate plane and the yz coordinate plane, respectively. Further, the relationship between the reflection displacement angle ξ1z and the liquid surface displacement angle α of the free liquid surface 1 is as follows.

[0018]

[Number 1] ^{ξ1z = cos -1 (cos 2 θ} cos2α + sin 2 θ) ξ2z = π / 2- cos -1 ((1- cos2α) sinθ cosθ)

Where α = 10 ′, θ = 50
In this case, ξ2z = 1.7 ″, and ξ2z is a value that can be neglected in terms of precision.

[0020]

２1x ′ = 2nαξ1z ′ = n · cos ⁻¹ (cos ² θ cos 2α + sin ² θ).

Therefore, the sensitivity to the liquid surface displacement angle α differs between the reflection displacement angle ξ1x 'and the reflection displacement angle ξ1z'. In the present invention, the reflected displacement angle ξ1x ′ and the reflected displacement angle ξ
The difference in sensitivity of the displacement angle from 1z 'is corrected by optical means, and by setting the same sensitivity, an optical axis which is always deviated at a constant rate in all directions is obtained.

Further description will be made with reference to FIG.

In the figure, reference numeral 4 denotes a liquid filling container provided in the main body of a measuring instrument or the like, and a free liquid surface 1 is formed by the liquid filled in the liquid filling container 4. The light beam emitted from the light source 6 is projected onto the free liquid surface 1 at a predetermined angle through the collimating lens 5 so as to be totally reflected on the free liquid surface 1, and the optical axis of the light beam is Y
It is located in the z coordinate plane.

In a state where the free liquid level 1 is not inclined,
A cylindrical lens system 9 having a pair of cylindrical lenses 7 and 8 is provided along the optical axis of the reflected light beam 3 totally reflected by the free liquid surface 1. Each of the cylindrical lenses 7 and 8 has a curvature only in one direction. The cylindrical lens 7 is a convex cylindrical lens having a focal length f1, and the cylindrical lens 8 is a concave cylindrical lens having a focal length f2.

A light receiver 10 is arranged so as to receive the light beam transmitted through the cylindrical lens system 9. The light receiver 1
In the case of 0, the light receiving portion is divided into four in a grid pattern, the outputs of the divided light receiving portions 10a and 10c are input to the differential amplifier 11, and the outputs of the split light receiving portions 10b and 10d are input to the differential amplifier 12. Is done. The differential amplifier 11 has the reflected light beam 3
And outputs the component in the z-axis direction of the displacement angle of the differential amplifier 1
Numeral 2 outputs the component of the displacement angle of the reflected light beam 3 in the x-axis direction, and the outputs of the differential amplifier 11 and the differential amplifier 12 are input to a calculator 13. The arithmetic unit 13 is connected to the differential amplifier 11
Based on the output of the differential amplifier 12 and the position of the optical axis of the light beam reflected by the light receiver 10, the inclination direction and the inclination angle α of the free liquid surface 1 are calculated, and the calculation result is output to a printer, a display, etc. Is displayed on the display device.

The operation will be described below.

First, as shown in FIG. 4A, when a light beam enters from the direction of the radius of curvature of the cylindrical lens 7, an angle between the reflected light beam 3 and the optical axis of the cylindrical lens 7, an incident angle a, The relationship with the exit angle a ′ from the cylindrical lens 8 is as follows:

[0028]

## EQU3 ## a '= (f1 / f2) a.

As shown in FIG. 4B, the angle between the reflected light beam 3 and the optical axis of the cylindrical lens 7 when the light beam is incident on a plane including the generatrix of the curved surface of the cylindrical lens 7, and the angle of incidence. a, the relationship with the exit angle a ′ from the cylindrical lens 8 is

[0030]

## EQU4 ## a = a '.

Here, with respect to the movement of the reflected light beam 3 when the free liquid surface 1 is tilted about the z-axis, the cylindrical lens system 9 is moved as shown in FIG. 4A. Therefore, the arrangement of the cylindrical lens system 9 is as shown in FIG. 4 (B) with respect to the movement of the reflected light beam when the free liquid surface 1 is inclined about the x-axis. Deploy.

Thus, in FIG. 3, the set incident angle θ to the liquid is 50 °, the inclination angle of the apparatus, that is, the inclination angle α of the free liquid surface 1 is
Assuming that 10 ′ and the refractive index of the liquid n = 1.4, the reflection displacement angle ξ1x ′ when the free liquid surface 1 is inclined around the x-axis and the free liquid surface 1 is inclined around the z-axis according to Equation 2. In this case, the reflected displacement angle 1z ′ is ξ1x ′ = 28 ′ and ξ1z ′ = 1, respectively.
8 '. Therefore, there is a sensitivity difference of (ξ1x '/ ξ1z') = 1.555 times between the reflection displacement angle ξ1x 'and the reflection displacement angle ξ1z'. Therefore, in this condition,

[0033]

５1x ′ = 2nα and ξ1z ′ = 1.286nα.

Therefore, from the equation (a), (f1 / f2) = 2 /
If 1.286, the displacement angle ξ1z ′ of the optical axis transmitted through the cylindrical lens system 9 is 1.286nα × 2 /
1.286 = 2nα, and after transmission through the cylindrical lens system 9, ξ1x ′ = ξ1z ′. Even if the free liquid surface 1 is inclined in any direction, the reflection displacement angle always has the same sensitivity to this inclination. Is obtained.

The change in the position on the light receiving surface of the light receiver 10 corresponds to the inclination of the free liquid surface 1, and the output difference between the light receiving units 10a, 10c, 10b, and 10d is determined by the differential amplifier. 11, the differential amplifier 12 detects, and the arithmetic unit 13 calculates the detection results of the differential amplifier 11 and the differential amplifier 12, thereby measuring the inclination angle α and the inclination direction of the free liquid surface 1. be able to.

It is to be noted that the photodetector 10 may be replaced with a photodetector having four divided light sections, and a PSD or a CCD element may be used.

Next, with respect to the embodiment shown in FIG. 3, the cylindrical lens system 9 is rotated by 90 ° to obtain (f 2 /
f1) = 1.555.

FIG. 5 shows the relationship between the incidence and emission of the reflected light beam 3 when the cylindrical lens system 9 is rotated by 90 °.
This will be described in (A) and (B).

As described above, the reflection displacement angle of the optical axis of the reflected light beam 3 with respect to the free liquid surface 1 is represented by the inclination angle α of the free liquid surface 1,
When the set incident angle θ of the light beam and the refractive index n of the liquid are set, the reflection displacement angle ξ1x ′ = 2 when the free liquid surface 1 is inclined about the x-axis.
When the free liquid surface 1 is inclined around the center of the nαz axis, the reflection displacement angle z1z ′ = 1.286nα.
Is after transmission through the cylindrical lens system 9,

[0040]

６1x ′ = 2nα × 1 / 1.555 = 1.286nα

Thus, the reflection displacement angle ξ1x 'is maintained as it is after passing through the cylindrical lens system 9,

[0042]

７1z ′ = 1.286nα.

Therefore, as in the above-described embodiment, the sensitivity of the light beam movement amount on the light receiving surface of the light receiver 10 to changes in the incident angle in all directions becomes the same. Thus, the light receiver 10
From the differential amplifier 11 and the differential amplifier 12
The inclination angle α of the free liquid surface 1 in the two axial directions, that is, the inclination of the device, can be measured by inputting to the arithmetic unit 13 through the arithmetic unit 13 and performing the arithmetic operation with the arithmetic unit 13.

Next, a specific example of the liquid enclosing container 4 will be described with reference to FIGS.

The liquid enclosing container 4 is fixed to the apparatus main body together with another lens system, or is constituted as a part of the apparatus. In this case, when the device is used in an environment where a temperature difference occurs, for example, when the device is carried out from indoors to outdoors, a temperature distribution occurs inside the liquid sealed in the liquid sealing container 4. If a temperature distribution occurs inside the liquid, the refractive index also shows a distribution corresponding to the temperature distribution, so that the refraction of the optical axis occurs inside the liquid. The specific example of the liquid filling container 4 shown in FIGS. 6 and 7 solves such a problem.

The details will be described below.

An inner case 21 similar to the outer case 20 is provided inside the inverted trapezoidal outer case 20. A flat space 22 is formed along the upper side surface of the inner case 21, and a light introduction path 23 and a light extraction path 24 communicating with the space 22 are formed. The axis of the light introduction path 23 coincides with the optical axis of the incident light beam, and the axis of the light exit path 24 coincides with the optical axis of the reflected light beam 3 when the free liquid surface 1 is horizontal. .

The heat transfer plate 25 is fixed to the bottom of the space 22. The heat transfer plate 25 has a window hole 26 formed at the center thereof so that an incident light beam and a reflected light beam can pass therethrough. Further, the light introduction path 2
3 and a stopper 27 made of transparent glass is fixed to the upper end of each of the light guide paths 24, and the stopper 27 hermetically seals a transparent liquid 28. The amount of the transparent liquid 28 is determined so as to form a free liquid surface.

The outer case 20 accommodates the inner case 21 and has a required surrounding space 2 around the inner case 21.
9 is formed. Further, the light introducing path 23 of the outer case 20 is
A transparent glass window 30 and a glass window 31 are provided at positions where the respective axes of the light guide paths 24 pass. The outer case 20 has an air-tight structure, and the surrounding space 29 is evacuated or filled with gas.

Further, the outer case 20 and the inner case 21 are made of a material having a low thermal conductivity such as a synthetic resin in order to suppress heat radiation and heat absorption to the outside.

As described above, the space 22 in which the transparent liquid 28 is sealed is flat and thin, and the heat transfer plate 25
Is provided, the speed of heat propagation is increased, and the uniformity of the temperature of the transparent liquid 28 in the temperature change state is improved.
Further, the surrounding space 29 forms a heat insulating layer with respect to the transfer of heat to and from the inner case 21, and suppresses the temperature change of the transparent liquid 28 or the temperature change speed.

Thus, the occurrence of a difference in temperature distribution inside the transparent liquid 28 is suppressed, and the refraction of the optical axis of the light beam and the change in the sectional shape of the light beam due to the change in the refractive index can be prevented. In addition, the stability is increased with respect to environmental temperature changes, and the measurement accuracy is improved.

Next, FIG. 8 shows another specific example of the liquid enclosing container 4, in which the inner case 21 is covered with an outer case 20 made of a heat insulating material without forming a surrounding space 29 around the inner case 21. The heat insulation layer is formed around the inner case 21 by the outer case 20.

It is needless to say that the shape of the liquid enclosing container 4 is not limited to the above embodiment.

[0055]

As described above, according to the present invention, an inclination detecting device for detecting an inclination by using the total reflection of an incident light beam on a free liquid surface is provided. It is possible to detect the amount of inclination of the lens, and it is not necessary to make electrical corrections only by optical correction using a cylindrical lens system. Therefore, the configuration is simple and measurement accuracy and reliability are improved. However, stable measurement can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a change in a reflection angle of a reflected light beam when a free liquid surface is inclined.

FIG. 2 is an explanatory diagram illustrating a change in a reflection angle of a reflected light beam when a free liquid surface is inclined.

FIG. 3 is a configuration diagram of one embodiment of the present invention.

FIGS. 4A and 4B are explanatory diagrams showing changes in the optical axis of a transmitted light beam with respect to a cylindrical lens system.

FIGS. 5A and 5B are explanatory diagrams showing changes in the optical axis of a transmitted light beam with respect to a cylindrical lens system.

FIG. 6 is a front sectional view showing a specific example of the liquid filling container.

FIG. 7 is a view taken in the direction of arrows AA in FIG. 6;

FIG. 8 is a front sectional view showing another specific example of the liquid filling container.

[Description of Signs] 1 Free liquid surface 2 Incident light beam 3 Reflected light beam 4 Liquid enclosure 6 Light source 9 Cylindrical lens system 10 Light receiver 28 Transparent liquid

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Kodaira 75-1 Hasunuma-cho, Itabashi-ku, Tokyo Inside Topcon Corporation (56) References JP-A-49-127657 (JP, A) JP-A-60-169706 (JP, A) JP-A-60-183511 (JP, A) JP-A-60-232502 (JP, A) JP-A-61-108908 (JP, A) JP-A-61-204515 (JP, A) JP-A-62-266447 (JP, A) JP-A-62-274211 (JP, A) JP-A-64-50908 (JP, A) JP-A-1-1455642 (JP, A) JP-A-5-256647 (JP, A) JP, A) JP-A 54-91860 (JP, U) JP-A 3-4213 (JP, U) JP-B 45-4208 (JP, B1) (58) Fields surveyed (Int. Cl. ⁷ , (DB name) G01C 9/00

Claims (4)

(57) [Claims] A liquid-filled container filled with a transparent liquid so as to form a free liquid surface; a light projecting system for projecting a light beam to be totally reflected at the free liquid surface onto the free liquid surface at a predetermined angle; A cylindrical lens system for transmitting the light beam reflected by the free liquid surface; and a light receiving device for receiving the reflected light beam transmitted through the cylindrical lens system, and the free liquid is received at the light receiving position of the reflected light beam on the light receiving surface of the light receiving device. An inclination detecting device for detecting an amount of inclination of a surface. 2. A plate-shaped space containing a transparent liquid.
Tilt detection device. 3. The inclination detecting device according to claim 2, wherein a heat transfer plate is provided on a bottom surface of the plate-shaped space. 4. The tilt detecting device according to claim 1, wherein a heat insulating layer is formed around the inner case filled with the transparent liquid.