JPH0456928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a surveying device using an optical fiber gyro.

(Background of the Invention) Among various conventional surveying methods, polygonal surveying and triangulation are relatively commonly used surveying methods. A transit (theodolite) is used for these surveys, but since the transit is equipped with a mechanical angle reading mechanism, it is heavy, and accordingly the tripod must be large and heavy. This led to increased weight and weight. Furthermore, since the scale is read, it has the disadvantage that reading errors cannot be removed. Another drawback is that it takes time to survey, as the azimuth angle (angle relative to a certain direction) cannot be directly measured. Furthermore,
Since other equipment is required to measure the azimuth angle, the amount of equipment to be transported increases. Some transits have built-in azimuth measurement devices, but these have the drawbacks of increased weight and size.

(Object of the Invention) The present invention solves the above-mentioned drawbacks, and aims to provide a surveying device that is easy to operate, small and lightweight, and free from reading errors.

(Summary of the Invention) The present invention provides a 3-axis optical fiber coil (hereinafter referred to as 3-axis optical fiber coil) in which optical fibers wound in each of three mutually orthogonal planes are formed into a hollow, substantially spherical shape for use in surveying equipment. The technical point is to combine a 3-axis optical fiber gyro and a collimating telescope.

(Embodiment) FIG. 1 shows an embodiment of a surveying device according to the present invention, which can be substituted for a transit.

Reference numerals 1, 2, and 3 indicate bobbins, each of which is wound with an optical fiber, and each constitutes a part of an optical fiber coil. The bobbins 1, 2, and 3 are assembled such that the bobbin 2 is placed inside the bobbin 1, and the bobbin 3 is placed inside the bobbin 2, so that their respective surfaces are orthogonal to each other, forming a hollow approximately spherical shape as a whole (hereinafter referred to as hollow). (referred to as a spherical body), which constitutes a three-axis optical fiber gyroscope. The cross section of each bobbin has an outer edge recess as shown in FIG. 2, and an optical fiber is wound in the recess. The hollow portion of the hollow spherical body accommodates the components of the fiber optic gyroscope, such as a power source, a light source, a light receiver, a signal processing system, a transmitter, or a display. Reference numeral 4 denotes a collimating telescope, to which the three-axis optical fiber gyroscope is integrally fixed. As is well known, the sighting telescope 4 is equipped with a tripod 5.
The rotary arm 53 is rotatably mounted on the rotary arm 53, which is rotatably mounted on the rotary arm 53, rotatably around the horizontal axis. The tripod 50 has a level measuring device 8 built in using a bubble, and a plumb bob 8 is installed coaxially with the axis of attachment of the freely rotating arm 53 to the tripod 50.
0 is attached.

Figure 3 shows the structure of the 1-axis element of the 3-axis optical fiber gyroscope shown in Figure 1.
is a polarization-maintaining optical fiber wound around bobbin 1,
11 is a circuit section including a power supply and a signal processing system, 12 is a super luminescence diode, a coupler,
A light source section 13 including a light guide fiber and a lens is a half prism that efficiently divides the light from the light source 12 into two equal parts. Therefore, the transmittance and reflectance are each about 50%. 14a, 14b are polarizing plates, 15a,
Reference numeral 15b denotes condensing lenses provided at both ends of the optical fiber 10. The optical fiber 10 is wound around the bobbin 1 to form a loop that produces a sannyac effect, and the light source 12 received by the lenses 15a and 15b is
The configuration is such that light from the loop enters from both ends of the loop. Reference numeral 16 denotes a phase modulation piezo element provided at one end of the loop, in which the optical fiber 10 is tightly wound.When a constant alternating current signal is applied to the piezo element 16, the optical fiber 10 expands and contracts. As a result, the clockwise and counterclockwise interference outputs of the optical fiber loop are modulated, increasing the measurement sensitivity to minute rotational angular velocities. The light that passes through the loop and is emitted to the end opposite to the incident end passes through the polarizing plates 14a and 14b again, respectively, and enters the half prisms 17a and 1.
7b and detected by each optical disk 18a, 18b. These optical detectors 18a and 18b make it possible to know the amount of light before sannyac interference.
The transmittance of the half prisms 17a and 17b is high, for example, set to about 90%. The light transmitted through the half prisms 17a and 17b undergoes sanitary interference at the half prism 13, and this interference light is detected by an optical detector 18c. The optical signals before and after the interference are sent to the optical detectors 18a and 18.
b, 18c photoelectrically converts the signal and sends it to the circuit section 11. The circuit section 11 removes the drift of the light source 12 by taking the difference between the amount of light after interference and the amount of light before interference. A transmitting section 19 sends the signal processed by the circuit section 11 to the receiving section by radio waves. The polarizing plates 14a and 14b are provided to remove noise generated when light passes through the loop of the optical fiber 10.

FIG. 4 is a diagram showing the configuration of a half prism etc. built into the spherical fiber loop of the triaxial fiber optic coil shown in FIG. 1. This is an example. Reference numerals 121 and 122 are optical branching couplers, which may be made by fusing, polishing/bonding, etching/dipping, prism, grating, or the like. The light branched into three by the optical branch couplers 121 and 122 is split into half prisms 13, 13', and 1.
3″.Half prisms 13, 13′,
13″ have half prisms 17a and 17, respectively.
a'17a'' and 17b, 17b'17b'' are combined. For example, the light incident on the half prism 13 travels equally to 17a and 17b. The optical fiber loop 10, which has almost passed through 17a, is rotated counterclockwise and enters the half prism 17b. A part of the light entering the half prism 17b goes to the optical detector 18b for intensity detection, and most of the rest goes to the half prism 13. On the other hand, most of the light that has passed through the half prism 17b goes around the fiber loop 10 clockwise and enters the half prism 17a. A portion of the light entering the half prism 17a passes to the optical detector 18a for intensity detection, and most of the remaining light passes to the half prism 13. The interference light of the clockwise and counterclockwise lights returning to the half prism 13 is detected by the optical detector 18c. Here, there is light returning to the light source 12, but if a superluminescence diode is used as the light source, coherence noise will not be generated because the coherence length is about several tens of microns. 5 and 6 are block diagrams showing a part of the circuit system of the surveying apparatus according to the present invention, with FIG. 5 showing the transmitting side and FIG. 6 showing the receiving side, respectively. In FIG. 5, 181, 182, and 183 are amplifiers that amplify the signals from the optical detectors 18a, 18b, and 18c. 184 is a multiplication circuit,
The product of the signals of the amplifiers 181 and 182, that is, the product of the clockwise and counterclockwise light intensities of the optical fiber loop 10, which is a sannyac loop, is the light intensity before sannyac interference. Reference numeral 183 denotes an amplifier that amplifies the intensity of the light after the sannyac interference. 1
85 is a differential circuit that takes the ratio between the amplifier 183 and the multiplier circuit 184, and is used to remove the drift contained in the output light of the light source 12.
By removing this drift, the accuracy of the surveying device can be improved. Reference numeral 186 denotes an integrating circuit which converts the one-axis, ie, one-dimensional, angular velocity signal output from the differential circuit 185 into an angle signal. Reference numerals 187 and 188 are integration circuits that convert the angular velocity signals of the other two axes into angle signals. 19 is a transmitter for each signal, 1
9a is a transmitting antenna.

In FIG. 6, 21 is a receiving section, 21a is a receiving antenna, 22 is a processing circuit that processes the signal from the receiving section 21, and 23 is a device that receives the signal from the processing circuit and sends the data to a device such as a printer 231 or a display 232. This is an output section that displays.

In FIG. 6, 222 is a three-dimensional angle determination circuit, which calculates and outputs the orientation as three-dimensional data from the orthogonal three-component angle signals from the integrating circuits 186, 187, and 188. Reference numeral 223 is a manual changeover switch that can be selectively connected to either the true north determination circuit 224 or the coordinate conversion circuit 225. That is, the changeover switch 223 is set to the true north determination circuit 2.
When connected to the 24 side, this surveying device, which is stationary facing a certain direction, outputs the west direction by detecting the rotation of the earth, so the positional relationship from the horizontal measuring device 8 attached to the tripod 50 is True north is determined from This data is stored in memory 227a.
Next, select switch 223 for measurement in a certain direction.
When connected to the coordinate conversion circuit 225 side, the due north data stored in the memory 227a mentioned above is used as coordinate conversion data, and the three-dimensional angle determination circuit 2
The coordinate conversion circuit 225 converts the coordinates of the data No. 22 to calculate the true orientation, which is stored in the memory 227b. The data stored in the memories 227a and 227b is output to the printer 231 or display 232 of the output section 23 at any time through the interface 226. The surveying apparatus shown in FIGS. 1-6 can simplify conventional transit surveying. The following is a survey procedure using the surveying device of the present invention.

FIG. 7 is a diagram illustrating an overview of surveying by the surveying device of the present invention. The operation of the surveying apparatus of the present invention will be explained below using FIGS. 1 to 7.

The distance between A and B is the base line length, and the accurate distance is measured by an appropriate method (actual measurement with a tape measure or measurement with a rangefinder).

Place this surveying device approximately above point B and adjust the tripod so that the down swing points to point B.

Point A is observed with a sighting telescope 4, and the sight is adjusted to match point A.

A first memory write operation of the surveying device after adjustment is performed, and the azimuth angle Θ0 (angle in the horizontal plane with respect to true north) and the elevation angle or depression angle Θ1 (angle with respect to the horizontal plane/hereinafter simply referred to as elevation angle) of the straight line AB are stored in the memory. Ru. If the foot of the perpendicular drawn from point A to the horizontal plane including point B is D, then Θ1 = ∠ABD
It is.

Next, the surveying device is rotated to observe point C with the collimating telescope 4, and the collimation is adjusted to match point C.

After said adjustment, a second memory write operation of the surveying device is performed, and the azimuth angle Θ2 and the elevation angle Θ3 of the straight line BC are stored in the memory. If the leg of the perpendicular drawn from point C to the horizontal plane including point B is E, then Θ3=∠
He is a CBE.

The value of ∠ABC is calculated from the data obtained by the first and second memory write operations, and the results are stored and displayed.

Next, place the surveying device on point A and place it on point B as described above.
∠CAB is calculated by observing the point and C point, and the results are stored and displayed.

ΔABC and their orientations are identified.

Triangulation is performed through the above steps.

8 and 9 show other embodiments of the method of branching the light source shown in FIG. 3 goes to the half prism 131 and the remaining 2/3 goes to the half prism 128. The light that has traveled to the half prism 128 travels equally to the half prisms 132 and 133. As described above, the light from the light source 12 is divided into three equal parts, and the subsequent structure is similar to that of the prism shown in FIG. This branching method is advantageous in that unnecessary light from each prism does not adversely affect interferometers for other dimensions. In Figure 9, the light source is branched using a grating (diffraction grating), 123 is the grating, 124, 12
5,126 is an interference prism, 141,142,1
43 is a light guide. grating 123
The light branched into zero-order light and ±first-order light enters light guides 141, 142, and 143. The light guiding guide includes a part that has a function of making the light enter the fiber using a condensing lens, etc., and a part that has a function of making the light enter the fiber with a condensing lens, etc.
25, 126.

(Effects of the invention) As is clear from the above explanation, since the 3-axis optical fiber gyro is used, there is no need to measure the direction, so the surveying procedure is simple, and there is no scale for reading angles, so it is small and lightweight. There is no need to incorporate a direction measuring device into the transit or to transport the direction measuring device for surveying work, and since there is no scale like conventional transits, it is light in weight, and there is no need to read the scale. (Direct reading using display means) There is no reading error, making surveying easier.

[Brief explanation of the drawing]

Fig. 1 is an external view of one embodiment of the present invention, Fig. 2 is a sectional view of a bobbin, Fig. 3 is a diagram showing the structure of a single-axis element of a triaxial optical fiber coil, and Fig. 4 is an example of a branching of a light source. 5 is a block diagram showing the circuit system on the transmitting side, FIG. 6 is a block diagram showing the circuit system on the receiving side, and FIG. 7 is a diagram showing an example of surveying using the surveying device of the present invention. Figure 8 is a diagram showing another example of branching of the light source, Figure 9 is a diagram showing another example of branching of the light source (explanation of main symbols), 1, 2, 3... bobbin,
8... Horizontal measuring device, 10... Optical fiber, 50...
...Tripod, 53...Freely rotating arm, 80...Plumb bob, 13, 13', 13''...Half prism,
17a, 17b, 17b', 17b''...Half prism.

Claims (1)

[Claims] 1. A 3-axis optical fiber coil in which three optical fibers are wound, and the respective optical fibers are combined so that the three planes formed by the windings intersect with each other, and the 3-axis optical fiber coil is horizontally wound. A support member that is rotatably supported around an axis and a vertical axis, a detector that detects the attitude of the support member, and a collimating telescope that is integrally provided with the three-axis optical fiber gyroscope. A surveying device using a characteristic optical fiber gyroscope.