JPH06147893A - Inclination detector - Google Patents

Abstract

PURPOSE:To allow detection of inclination only through a unilateral optical system by providing a light receiving unit for receiving reflection luminous flux transmitted through an anamorphic prism and detecting inclination amount at a position on the light receiving plane of the light receiving unit where the reflection luminous flux is received. CONSTITUTION:A light receiving unit 10 is arranged to receive luminous flux transmitted through an anamorphic prism system 9. The light receiving unit 10 has light receiving part split in checkered pattern into four sections, i.e., light receiving parts 10a, 10c having outputs connected with a differential amplifier 11 and light receiving parts 10b, 10d having outputs connected with a differential amplifier 12. The amplifier 11 outputs z-axis component of the displacement angle of reflection luminous flux whereas the amplifier 12 outputs x- direction component thereof. Outputs from the amplifiers 11, 12 are fed to an operating unit 13. The operating unit 13 operates the position of the optical axis of reflection luminous flux at the light receiving unit 10 based on outputs from the amplifiers 11, 12 and measures inclination angle and inclining direction of the liquid plane 1.

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 in surveying equipment, measuring equipment, etc., for detecting a change in tilt amount or for correcting the tilt of the device so as to detect the tilt amount. It is a thing.

[0002]

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

As a method of detecting the inclination of the reference surface of a surveying instrument, measuring instrument, etc., there is a method utilizing the free liquid surface.

In this method, a light beam is made incident on the 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 this free liquid surface, a reflection angle with the same sensitivity with respect to the inclination of the free liquid surface is obtained in all two-dimensional directions. It is possible to obtain the inclination of the reference plane.

However, in practice, it is difficult to use the liquid such as mercury described above in terms of cost and safety, and a transparent liquid such as silicon oil is 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 above-mentioned critical value. An incident angle θ corresponding to the angle is required. Thus, in the conventional inclination detecting device using the free liquid surface, the light beam is incident on the free liquid surface at a predetermined angle.

When a light beam is incident on the free liquid surface at a predetermined angle, it is different by 2 with respect to the inclination of the free liquid surface.
The change in the reflection angle of the reflected light with respect to the axial direction is not uniform. Therefore, in the inclination detecting device using the free liquid surface, measures are taken against the uneven variation of the reflection angle.

[0007] One of the conventional tilt detection devices is to make light beams of two different optical axes incident on the free liquid surface at a predetermined angle, receive reflected light by a light receiver, and change the light receiving position of each light receiver. The inclination of the two optical axes is detected, and the inclination of the reference plane such as a surveying instrument or measuring instrument with respect to the horizontal plane is calculated from the detected inclination of the two optical axes.

As another conventional inclination detecting device which makes a light beam incident on a free liquid surface at a predetermined angle and utilizes the 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, the change amount of the light receiving position in the two axis directions of the light beam in the light receiver, that is, in the two directions of the optical axis direction of the light beam and the other axis direction is obtained, and further calculated by a surveying instrument, There is a device that obtains the reference plane inclination such as measuring equipment. In the other conventional tilt detecting device, the sensitivity of the position change on the light receiving surface with respect to the tilt change is different in two directions, that is, the optical axis direction of the light beam and the other axis direction. Therefore, the difference in sensitivity is electrically corrected. is doing.

[0009]

Among the conventional tilt detecting devices, the former one has a drawback that the structure of the device is complicated because the projection system of the light flux is two optical systems, and the conventional tilt detecting device. In the latter case of the device, since the reflection angle of the light flux from the free liquid surface has a sensitivity difference in the biaxial direction on the light receiving surface with respect to the tilt amount of the free liquid surface, at least one detection result is obtained. There is a problem that an electrical correction is required and an electrical processing system for the correction needs to be separately provided, which makes the processing system complicated.

In view of the above situation, the present invention is intended to detect the inclination of the reference plane by using only a uniaxial optical system and without providing an electrical processing system for additional correction.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a liquid encapsulation container in which a transparent liquid is enclosed so as to form a free liquid surface, and a light beam for totally reflecting the free liquid surface at a predetermined angle on the free liquid surface. A projection system for projecting, an anamorphic prism system for transmitting the light flux reflected by the free liquid surface, and a light receiver for receiving the reflected light flux transmitted through the anamorphic prism system, The inclination amount of the free liquid surface is detected at the light receiving position of the reflected light beam on the light receiving surface, and the uniformity of the temperature distribution with respect to the temperature change of the transparent liquid is further improved.

[0012]

When the liquid sealing container is tilted and the incident angle of the light beam with respect to the free liquid surface is relatively changed, the change of the reflection angle has different sensitivity depending on the tilt direction of the free liquid surface. This difference in sensitivity can be optically corrected by the anamorphic prism system, and the tilt amount 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, when a temperature distribution is generated in the transparent liquid, the refractive index of the transparent liquid becomes uneven, which causes refraction of the optical axis and the like, which affects the measurement results, but by improving the uniformity of the temperature distribution of the transparent liquid. Improves measurement stability and reliability with respect to environmental temperature changes.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, when a light beam is incident on the free liquid surface at a predetermined angle and the light beam is totally reflected by the free liquid surface, when the free liquid surface is inclined relative to the light beam, It will be described with reference to FIGS. 1 and 2 that the sensitivities of changes in the reflection angle differ depending on the direction of inclination of the surface.

In practice, the free liquid surface is kept horizontal and the incident direction of the light beam changes, but the following description is made assuming that the incident direction of the light beam is constant and the free liquid surface is inclined.

In the figure, 1 is 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. Free liquid level 1
And an xz coordinate plane formed by the coordinate axes x and z are substantially coincident with each other, and a coordinate axis perpendicular to the coordinate plane is y. It is assumed that the optical axis of the incident light beam 2 exists in the zy coordinate plane formed by the coordinate axes z and y. If the free liquid surface 1 is tilted by an angle α about the coordinate axis x from this state, 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 reflection displacement angle ξ1x is ξ
1x = 2α, and in this case, the reflection displacement angle ξ2x in the xy coordinate plane does not occur. In the figure, 14 indicates a mirror.

On the other hand, if the free liquid surface 1 is inclined by the angle α about the coordinate axis z, the reflected light flux 3 moves away from the xy coordinate plane and the yz coordinate plane, respectively. Therefore, the reflection displacement angle ξ1z and the reflection displacement angle ξ2z appear on the xy coordinate plane and the yz coordinate plane, respectively. Furthermore, the relationship between the reflection displacement angle ξ1z and the liquid surface displacement angle α of the free liquid surface 1 is

[0018]

[Equation 1] ξ1z = cos ^-1 (cos ² θ cos 2α + sin ² θ) ξ 2z = π / 2-cos ^-1 ((1- cos 2α) sin θ cos θ)

For example, α = 10 ', θ = 50
If it is °, then ξ2z = 1.7 ″, and ξ2z is a value that can be neglected in terms of precision.

[0020]

[Number 2] ξ1x '= 2nα ξ1z' = n · cos -1 a ^{(cos 2 θ cos2α + sin 2} θ).

Therefore, the sensitivity to the liquid surface displacement angle α is different between the reflective displacement angle ξ1x 'and the reflective displacement angle ξ1z'. In the present invention, the reflection displacement angle ξ1x ′ and the reflection displacement angle ξ
The difference in the sensitivity of the displacement angle from 1z 'is corrected by the optical means so that the sensitivity becomes the same, so that the optical axis that deviates at a constant rate in all directions can be obtained.

Further explanation will be given with reference to FIG.

In the figure, reference numeral 4 denotes a liquid sealing container provided in the main body of a device such as a measuring machine, and the free liquid level 1 is formed by the liquid sealed in the liquid sealing container 4. Further, the light beam emitted from the light source 6 is projected onto the free liquid surface 1 through the collimator lens 5 at a predetermined angle so as to be totally reflected with respect to the free liquid surface 1, and the optical axis of the light beam is as described above. As you did
Position in the z coordinate plane.

With the free liquid surface 1 not tilted,
An anamorphic prism system 9 including a pair of wedge-shaped prisms 7 and 8 is arranged along the optical axis of a reflected light beam 3 that is totally reflected by the free liquid surface 1.

The photodetector 10 is arranged so as to receive the light flux transmitted through the anamorphic prism system 9. The photodetector 10 has a photodetector section divided into four in a checkerboard pattern, outputs of the divided photodetection sections 10a and 10c are input to a differential amplifier 11, and outputs of the divided photodetection sections 10b and 10d are differential amplifier. 12 is input. The differential amplifier 11 outputs a component of the displacement angle of the reflected light beam 3 in the z-axis direction, and the differential amplifier 12 outputs a component of the displacement angle of the reflected light beam 3 in the x-axis direction,
The outputs of the differential amplifier 11 and the differential amplifier 12 are input to the calculator 13. The arithmetic unit 13 is the differential amplifier 1
1 and the output of the differential amplifier 12, the position of the optical axis of the reflected light beam at the light receiver 10 is calculated, the tilt direction and tilt angle α of the free liquid surface 1 are calculated, and the calculation result is printed by a printer or a display. Etc. are displayed on the display device.

The operation will be described below.

In FIG. 3, the incident angle θ on the liquid is θ = 50.
°, the tilt angle of the device, that is, the tilt angle α of the free liquid level 1 = 10 ',
Assuming that the refractive index of the liquid is n = 1.4, the reflection displacement angle ξ1x ′ when the free liquid surface 1 is tilted around the x-axis is calculated by Equation 2.
And the reflection displacement angle ξ when the free liquid surface 1 is tilted about the z-axis
1z 'becomes ξ1x' = 28 'and ξ1z' = 18 ', respectively. Therefore, the reflection displacement angle ξ1x ′ and the reflection displacement angle ξ1z ′ are
And there is a difference in sensitivity of (ξ1x ′ / ξ1z ′) = 1.555 times. Therefore, under this condition,

[0028]

## EQU3 ## ξ1x '= 2nα and ξ1z' = 1.286nα.

The anamorphic prism system 9 optically corrects the sensitivity difference.

Now, the anamorphic prism system 9 will be described.

The prism apex angles of the wedge-shaped prisms 7 and 8 constituting the anamorphic prism system 9 are a7 and a8,
The relative angle between the wedge-shaped prisms 7 and 8 is b, and the refractive index is ng,
Letting incident light flux Din and outgoing light flux Dout be

[0032]

## EQU00004 ## Magnification M = (Din / Dout) = cos ² a / (1-ng ² .sin ² a)

Therefore, the angular magnification is approximately 1 / M. Therefore,

[0034]

(5) M = 2nα / 1.286nα = 1.555

The prism apex angle is set to a7, a
8, the relative angle between the wedge prisms 7 and 8 is b, and the refractive index is ng
If, for example, ng = 1.51, then a7,
a8 = 27.732 °, b = 44.793 °),
Ξ1x ′ after passing through the anamorphic prism system 9 is
It is converted into 2nα / 1.555 = 1.286nα, and after passing through the anamorphic prism system 9, ξ1x ′ = ξ1z ′.

Thus, the optical axis of the reflected light flux 3 after passing through the anamorphic prism system 9 always has a uniform reflection displacement angle with respect to the inclination of the free liquid surface 1 in all directions, and the received light is received. The amount of movement of the light flux on the surface shows the same sensitivity. Therefore, the change of the position on the light receiving surface of the light receiver 10 corresponds to the inclination of the free liquid surface 1, and the light receiving portions 10a, 10c, 10b, 10
The differential amplifier 11 and the differential amplifier 12 detect the output difference of d, and the computing unit 13 computes the detection results of the differential amplifier 11 and the differential amplifier 12. The inclination angle α and the inclination direction can be measured.

The photodetector 10 may be replaced with one having a photodetector divided into four parts, and a PSD or CCD element may be used.

Next, as compared with the embodiment shown in FIG. 3, the anamorphic prism system 9 is rotated by 90 °, and M =
The apex angles of the wedge-shaped prisms 7 and 8 may be appropriately selected to be a7 and a8, the relative angles of the wedge-shaped prisms 7 and 8 to be b, and the refractive index to ng so as to be 1 / 1.555.

Next, a concrete example of the liquid enclosure 4 will be described with reference to FIGS.

The liquid-filled container 4 is fixed to the main body of the apparatus together with another lens system, or is constructed 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 it is carried out from the room to the outdoors, a temperature distribution occurs inside the liquid sealed in the liquid sealing container 4. When a temperature distribution is generated inside the liquid, the refractive index also shows a distribution corresponding to the temperature distribution, so that refraction of the optical axis occurs inside the liquid. The specific example of the liquid sealing container 4 shown in FIGS. 7 and 8 solves such a problem.

The details will be described below.

An inner case 21 similar to the outer case 20 is provided inside the outer case 20 having an inverted trapezoidal shape. A plate-like space 22 is formed along the upper side surface of the inner case 21, and a light introducing path 23 and a light guiding path 24 communicating with the space 22 are formed. The axis of the light introducing path 23 is aligned with the optical axis of the incident light beam, and the axis of the light guiding path 24 is aligned with the optical axis of the reflected light beam 3 when the free liquid surface 1 is horizontal. .

A heat transfer plate 25 is fixed to the bottom surface of the space 22. The heat transfer plate 25 has a window hole 26 formed in the center thereof so that the incident light flux and the reflected light flux can pass therethrough. In addition, the light introduction path 2
3, and a plug 27 made of transparent glass is fixed to the upper end of each of the light guiding paths 24, and the transparent liquid 28 is hermetically sealed by the plug 27. The amount of the transparent liquid 28 enclosed is determined so as to form a free liquid surface.

The outer case 20 accommodates the inner case 21, and a required surrounding space 2 is provided around the inner case 21.
9 is formed. In addition, the light introduction path 23 of the outer case 20
Then, a transparent glass window 30 and a glass window 31 are provided at positions where the respective axes of the light guiding paths 24 pass. The outer case 20 has an airtight 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 small thermal conductivity such as 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 bottom surface has a heat transfer plate 25.
Is provided, the heat propagation speed is increased and the temperature uniformity of the transparent liquid 28 in the temperature changing state is improved.
Further, the surrounding space 29 forms a heat insulating layer for transferring heat to and from the inner case 21 to suppress the temperature change of the transparent liquid 28 or the temperature change speed.

Thus, the difference in temperature distribution inside the transparent liquid 28 is suppressed, and it is possible to prevent the refraction of the optical axis of the light flux and the change in the cross-sectional shape of the light flux due to the change in the refractive index. In addition, the stability is increased even when the environmental temperature changes, and the measurement accuracy is improved.

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

Needless to say, the shape of the liquid container 4 is not limited to the above embodiment.

[0050]

As described above, according to the present invention, the tilt detecting device detects the tilt by utilizing the total reflection of the incident light beam on the free liquid surface, and has a uniaxial light beam projection system in all directions. Of the anamorphic prism system, it is possible to detect the tilt amount of the anamorphic prism system, and there is no need to make electrical correction by only optical correction by the anamorphic prism system. Stable measurements can be performed even in certain environments.

[Brief description of 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 an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a change of an optical axis of a transmitted light flux with respect to an anamorphic prism system.

5A and 5B are explanatory diagrams showing changes in the optical axis of a transmitted light flux with respect to an anamorphic prism system.

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

FIG. 7 is a view on arrow AA of FIG.

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

[Explanation of symbols]

 1 Free liquid level 2 Incident light flux 3 Reflected light flux 4 Liquid enclosure 6 Light source 9 Anamorphic prism system 10 Light receiver 28 Transparent liquid

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Junichi Kodaira 75-1 Hasunumacho, Itabashi-ku, Tokyo Topcon Co., Ltd.

Claims (4)

[Claims] 1. A liquid enclosing container in which a transparent liquid is enclosed so as to form a free liquid surface, and a light projecting system for projecting a light beam onto the free liquid surface at a predetermined angle so as to totally reflect on the free liquid surface. An anamorphic prism system that transmits the light flux reflected by the free liquid surface and a light receiver that receives the reflected light flux that has passed through the anamorphic prism system are provided. A tilt detecting device characterized in that the tilt amount of a free liquid surface is detected at a light receiving position. 2. The transparent liquid is enclosed in a plate-like space.
Tilt detection device. 3. The inclination detecting device according to claim 2, wherein a heat transfer plate is provided on the bottom surface of the plate-shaped space. 4. The tilt detecting device according to claim 1, wherein a heat insulating layer is formed around an inner case enclosing a transparent liquid.