JP2000105119A - Position measuring device and surveying instrument using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a position measuring device using a liquid member having a free surface, and is particularly suitable for a tilt sensor of a surveying instrument. It is an object of the present invention to provide a position measuring device that can be configured compact by arranging it on the optical path, and a surveying instrument using the same. [Configuration] According to the present invention, a dark-field pattern is formed by arranging two-dimensional positions, and a first optical system separates light from the dark-field pattern into two directions and forms a first light-collecting light. An element for condensing light from the first optical system in a first direction, and a second condensing element for condensing light from the first optical system in a second direction different from the first direction. The first light receiving element receives the condensed pattern image, the second light receiving element receives the condensed pattern image, The position on the pattern is calculated based on the signal, and the dark field pattern is arranged at an equal pitch with respect to the longitudinal direction of the light-collecting element, and the width of the pattern as viewed from a direction orthogonal thereto is the same. Has been placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring apparatus using a liquid member having a free surface, and is particularly suitable for a tilt sensor of a surveying instrument. The present invention relates to a position measuring device which can be compactly arranged by being arranged on a road, and a surveying instrument using the same.

[0002]

2. Description of the Related Art A bubble tube 10000 shown in FIG. 12 has conventionally been used as an element for detecting the inclination of a surveying instrument. In the bubble tube 10000, the inclination can be measured by enclosing a bubble 5000 inside, forming electrodes 6000 and 7000, and electrically measuring the capacitance.

[0003]

However, the above-mentioned bubble tube 10000 has a problem that it is susceptible to impacts and requires high mechanical precision because the outer peripheral portion is made of glass, so that the cost is high.

Further, in order to measure the inclination in the X and Y directions, two bubble tubes 10000 are required in two axial directions, which has been a cause of high cost.

Further, there is a problem that the bubble tube 10000 is affected by a change in ambient temperature and must be corrected for the change in temperature.

The above conventional bubble tube 10000 can measure with high accuracy when measuring a horizontal plane as a reference, but when directly detecting a tilt, the response characteristic is poor and the direct tilt is detected. And the detection range is narrow.

[0007]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned problems, and has a dark-field pattern arranged so as to indicate a two-dimensional position and light from the dark-field pattern in two directions. A first optical system for separation, a first light-collecting element for condensing light from the first optical system in a first direction, and light from the first optical system. For focusing light in a second direction different from the first direction.
, A first light receiving element for receiving the pattern image condensed by the first light condensing element, and a light receiving element for receiving the pattern image condensed by the second light collecting element And a processing means for calculating a position on the pattern based on the light receiving signals of the first and second light collecting elements. The field-of-view patterns are arranged at equal pitches with respect to the longitudinal direction of the first light-condensing element and the second light-condensing element, respectively, and have the same pattern width when viewed from a direction orthogonal to the light condensing elements. It is formed from the arranged two-dimensional pattern.

Further, the dark-field pattern of the present invention is characterized in that:
Direction, each of the second direction has a certain width,
It is also possible to adopt a configuration in which they are sequentially arranged at an equal pitch.

In the dark field pattern according to the present invention, a first pattern in which each of the first direction and the second direction is modulated with at least a first period, and a first pattern different from the first pattern. It is also possible to have a second pattern modulated at two periods, and the first pattern and the second pattern are sequentially arranged at an equal pitch.

Further, the modulation of the first pattern and the second pattern according to the present invention may be performed by spatial modulation for changing a line width.

The present invention also provides a light source, a first optical system for collimating the light from the light source, and a two-dimensional position for transmitting the light from the first optical system. , A liquid member having a free surface for reflecting the dark field pattern, a second optical system for imaging the pattern reflected by the liquid member, and a second A first light condensing element for condensing light from the first optical system in a first direction, and condensing light from the second optical system in a second direction different from the first direction. A second light collecting element, a first light receiving element for receiving the pattern image condensed by the first light condensing element, and a light condensing element that is condensed by the second light condensing element. A second light receiving element for receiving the pattern image, the first light collecting element and the second light collecting element Based on a photodetection signal of the consists of a processing means for calculating an inclination from a position on the dark field pattern, the dark field pattern is composed is formed from the absolute pattern.

Further, the present invention may be arranged such that a half mirror is disposed on an optical path of the liquid member and the second optical system.

Further, the present invention may be arranged such that the light source and the surface of the liquid member having a free surface for reflecting light from the light source are arranged in a conjugate relationship.

Further, the liquid member of the present invention can be formed integrally with the half mirror.

Further, the arithmetic processing means of the present invention obtains a motion equal to or more than the pitch interval of the pattern by an absolute pattern, and obtains a motion equal to or less than the pitch interval of the pattern by calculating the phase of the pattern by Fourier transform. It is also possible to configure to obtain the inclination.

In the present invention, a swingable suspension member may be used instead of the liquid member having a free surface.

The dark-field pattern of the present invention has at least a first pattern modulated in a first cycle and a second pattern modulated in a second cycle different from the first cycle.
The first pattern and the second pattern may be sequentially arranged at an equal pitch.

Further, in the present invention, the first pattern and the second pattern may be modulated by spatial modulation for changing a line width.

According to the present invention, a uniform third pattern is provided in addition to the first pattern and the second pattern, and the first pattern, the second pattern, and the third pattern are sequentially arranged at an equal pitch. By doing so, it can also be configured.

Further, a first light-collecting element and a second light-collecting element,
Further, at least one area sensor may be used instead of the first light receiving element and the second light receiving element.

The surveying instrument of the present invention may be attached to the surveying instrument main body and detect the inclination of the surveying instrument main body.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention constructed as described above
The first optical system separates the light from the dark field pattern in two directions by arranging the dark field pattern so as to indicate a two-dimensional position. The light from the system is focused in a first direction, and a second light-collecting element
The light from the optical system is collected in a second direction different from the first direction, the first light receiving element receives the pattern image collected by the first light collecting element, The second light-receiving element receives the pattern image condensed by the second light-collecting element, and the arithmetic processing means performs pattern-based image processing based on the light-receiving signals of the first light-condensing element and the second light-condensing element. Are calculated, and the dark-field pattern is arranged at an equal pitch with respect to the longitudinal direction of the first light-condensing element and the second light-condensing element, respectively, and the width of the pattern viewed from the direction orthogonal to They are arranged to be the same.

In the dark field pattern of the present invention, each of the first direction and the second direction has a constant width, and can be sequentially arranged at an equal pitch.

The dark-field pattern according to the present invention includes a first pattern modulated in at least a first cycle in a first direction and a second direction, and a second cycle different from the first pattern. , And the first pattern and the second pattern can be sequentially arranged at an equal pitch.

Further, the modulation of the first pattern and the second pattern of the present invention can be performed by spatial modulation for changing the line width.

According to the present invention, the first optical system makes the light from the light source parallel, and a dark field pattern arranged so as to indicate a two-dimensional position allows the light from the first optical system to pass therethrough. The half mirror deflects the dark field pattern, the first liquid member having a free surface reflects the pattern emitted from the half mirror, and the second optical system reflects the pattern reflected by the first liquid member. The first light-collecting element focuses light from the second optical system in a first direction, and the second light-collecting element focuses light from the second optical system on the first Light is condensed in a second direction different from the first direction, a first light receiving element receives the pattern image condensed by the first light condensing element,
The light receiving element receives the pattern image condensed by the second light condensing element, and the arithmetic processing means performs a dark field based on a light receiving signal between the first light condensing element and the second light condensing element. The tilt is calculated from the position on the pattern, and the dark field pattern is formed from an absolute pattern.

According to the present invention, the half mirror can be arranged on the optical path of the liquid member and the second optical system.

In the present invention, the light source and the surface of the liquid member having a free surface for reflecting the light from the light source can be arranged in a conjugate relationship.

Further, the liquid member of the present invention can be integrated with a half mirror.

Further, the arithmetic processing means of the present invention obtains a motion equal to or greater than the pitch interval of the pattern by using an absolute pattern, and obtains a motion equal to or less than the pitch interval of the pattern by calculating the phase of the pattern by Fourier transform. You can also determine the slope.

In the present invention, instead of the liquid member having the free surface, a swingable suspension member may be used.

The dark-field pattern of the present invention has at least a first pattern modulated in a first cycle and a second pattern modulated in a second cycle different from the first cycle. The second pattern and the second pattern can be sequentially arranged at the same pitch.

Further, according to the present invention, the modulation of the first pattern and the second pattern can be performed by spatial modulation that changes the line width.

According to the present invention, a uniform third pattern is provided in addition to the first pattern and the second pattern. The first pattern, the second pattern, and the third pattern may be sequentially arranged at an equal pitch. it can.

Further, a first light-collecting element and a second light-collecting element,
Further, at least one area sensor may be used instead of the first light receiving element and the second light receiving element.

Further, the surveying instrument of the present invention may be attached to the surveying instrument main body to detect the inclination of the surveying instrument main body.

[0037]

【Example】

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

FIG. 1 shows an inclination sensor 100 according to the first embodiment.
0, the light source 100, the condenser lens 200, the dark field pattern 300, the first pattern relay lens 410, and the first half mirror 5
10, a liquid member 600 having a free surface, a second pattern relay lens 420, and a second half mirror 52.
0, a first cylindrical lens 710, a second cylindrical lens 720, and a first light receiving element 810
, A second light receiving element 820, and the arithmetic processing means 16.

Although the light source 100 of the first embodiment is an LED, any light source can be used.

The condenser lens 200 includes a light source 100
This is for collimating light from the first optical system, and corresponds to the first optical system.

The dark-field pattern 300 is for forming a pattern image on the first light receiving element 810 and the second light receiving element 820.

FIG. 2 shows a two-dimensionally arranged dark field pattern 300 of the first embodiment, which is formed by forming a plurality of transparent pattern portions on a black mask portion.

FIG. 3 shows a dark field pattern 3 of the first embodiment.
00 shows a plurality of transparent pattern portions in an enlarged manner, and the pattern portions are arranged in a direction orthogonal to the X-axis direction and the Y-axis direction. That is, the dark-field pattern 300 of the first embodiment is an absolute pattern indicating an absolute position in two axial directions (X-axis direction and Y-axis direction).
The pattern is crossed in the axial direction.

Here, the column in the X-axis direction is i (i = 1 to 1).
N), the row on the Y axis is j (j = 1 to K), and a specific pattern is represented by P _ij (i = 1 to N, j = 1 to K). In the case of FIG. 3, N = 9 and K = 8.

Therefore, the first row (J = 1) will be described.

In the pattern of the first row, a first pattern A, a second pattern B, a third pattern C, and a fourth pattern R are repeatedly arranged at equal intervals (p). That is, each block is continuously formed as a set of four types of patterns, and the block arranged on the leftmost side is defined as 1 block.
Defined as a block, R, A (1), B (1), C (1)
R, A (2), B (2), C (2),
R, A (3), B (3), C (3),... Are repeatedly arranged.

That is, P ₁₁ = R, P ₂₁ = A ₁ , P ₃₁ = B ₁ ,
P ₄₁ = C ₁ , P ₅₁ = R, P ₆₁ = A ₂ , P ₇₁ = B ₂ , P ₈₁ =
C ₂ , P ₉₁ = R

Next, the first column (i = 1) will be described.

In the patterns of the first row, a first pattern A, a second pattern B, a third pattern C, and a fourth pattern R are repeatedly arranged at equal intervals (p). For simplicity, each block is continuously formed as a set of four types of patterns.
Defined as a block, R, A (1), B (1), C (1)
R, A (2), B (2), C (2),
R, A (3), B (3), C (3),... Are repeatedly arranged.

That is, P ₁₁ = R, P ₁₂ = A ₁ , P ₁₃ = B ₁ ,
P ₁₄ = C ₁ , P ₁₅ = R, P ₁₆ = A ₂ , P ₁₇ = B ₂ , P ₁₈ =
The C _2.

The first pattern relay lens 410 guides the light passing through the dark field pattern 300 to the first half mirror 510.

The first half mirror 510 of the first embodiment.
Is a beam splitter provided with a semi-transmissive surface 511.
The light that has entered the first half mirror 510 passes through the semi-transmissive surface 511, travels upward, and enters the liquid member 600 having a free surface. The light reflected by the liquid member 600 having the free surface is reflected by the first half mirror 51.
The light is reflected from the zero semi-transmissive surface 511 and travels toward the second pattern relay lens 420.

Note that the first half mirror 510 has a structure having an inclined surface 512 inclined with respect to the reflected light from the light source 100.

The light incident on the first half mirror 510 from the light source 100 passes through the semi-transmissive surface 511 and goes upward, but there is a part of the light reflected on the semi-transmissive surface 511. A part of the reflected light is supplied to the first half mirror 510
After being reflected at the end face of the
Again, the light passes through the semi-transmissive surface 511 and travels toward the second pattern relay lens 420.

The reflected light reflected from the semi-transmissive surface 511 is
This may hinder tilt detection or cause an error. Therefore, in the first embodiment, the first half mirror 5
The end face 10 is configured to be an inclined surface 512 that is inclined with respect to the transmitted light from the light source 100.

As a result, the light from the light source 100 reflected on the semi-transmissive surface 511 is reflected again on the inclined surface 512, but this retroreflected light does not travel in the same optical path in the opposite direction. The second pattern relay lens 420 is not incident on the first light receiving element 810 and the second light receiving element 820 via the second pattern relay lens 420, and an effect is obtained that high-precision measurement can be performed.

Then, the first half mirror 510 of the embodiment
May have a configuration having a surface inclined with respect to the reflected light from the light source 100.

The light source 100 and the liquid member 60 having a free surface for reflecting light from the light source 100
0 may be arranged in a conjugate relationship with the surface.

In this case, there is an effect that the reflection area on the surface of the liquid member 600 is minimized, and the error due to the surface tension of the liquid can be minimized. Further, the volume of the liquid member 600 can be reduced.

The liquid member 600 having a free surface is filled with a liquid having an appropriate viscosity such as silicon oil. Since the liquid member 600 has a free surface, the surface is always kept horizontal.

Further, the liquid member 600 of this embodiment can be formed integrally with the first half mirror 510.

Then, the first half mirror 51 of the present embodiment
In the case of 0, an antireflection film can be applied to the surface in contact with the liquid member 600.

The refractive index of the liquid member 600 of the present embodiment and the refractive index of the first half mirror 510 may be configured to have approximate values.

The first half mirror 510 corresponds to a half mirror.

The second pattern relay lens 420 transmits the light reflected by the liquid member 600 having a free surface and reflected by the first half mirror 510 to the first light receiving element 81.
0 and for imaging on the second light receiving element 820. That is, the second pattern relay lens 420 is for forming an image of the dark field pattern 300 on the first light receiving element 810 and the second light receiving element 820.

The second pattern relay lens 420
Corresponds to the second optical system, and is disposed at a position apart from the first light receiving element 810 and the second light receiving element 820 by the focal length f of the second pattern relay lens 420.

The second half mirror 520 separates the image of the dark field pattern 300 into a first light receiving element 810 and a second light receiving element 820.

The first cylindrical lens 710 is
The image of the dark field pattern 300 is condensed in the axial direction. Note that the first cylindrical lens 710 is
This corresponds to the first light-collecting element.

For example, for the first row, P ₁₁ = R, P
₂₁ = A ₁ , P ₃₁ = B ₁ , P ₄₁ = C ₁ , P ₅₁ = R, P ₆₁ =
A ₂ , P ₇₁ = B ₂ , P ₈₁ = C ₂ , and P ₉₁ = R are condensed as shown in the right corner of FIG.

That is, P _i1 (i = 1 to 9) is condensed as in the right corner.

Therefore, light can be collected in all rows in the X direction.

Therefore, the light collection of “P _i1 (i = 1 to 9) is
J = 1 to 8 lines ".

As a result, an absolute pattern indicating the position in the Y direction condensed in the X direction at the pitch p is formed at the right corner.

The second cylindrical lens 720 has a Y
The image of the dark field pattern 300 is condensed in the axial direction. The second cylindrical lens 720 corresponds to a second light-collecting element.

For example, for the first column, P ₁₁ = R, P
₁₂ = A ₁ , P ₁₃ = B ₁ , P ₁₄ = C ₁ , P ₁₅ = R, P ₁₆ =
A ₂ , P ₁₇ = B ₂ , and P ₁₈ = C ₂ are focused as shown in the lower corner of FIG.

Therefore, light can be collected in all rows in the Y direction.

The light condensing at P _1j (j = 1 to 8) is performed when i = 1 to
Execute up to 9 columns "

As a result, an absolute pattern indicating the position in the X direction condensed in the Y direction at the pitch p is formed like the lower corner.

First light receiving element 810 and second light receiving element 8
Numeral 20 is for receiving the image of the dark-field pattern 300 and converting it into an electric signal.
A CD (Charge Coupled Device) linear sensor is employed.

The first light receiving element 810 receives an image condensed in the X-axis direction by the first cylindrical lens 710, and Y light condensed in the X direction at a pitch p.
An absolute pattern indicating the position in the direction can be received.

The second light receiving element 820 receives an image condensed in the Y axis direction by the second cylindrical lens 720, and the X light condensed in the Y direction at a pitch p.
An absolute pattern indicating the position in the direction can be received.

The arithmetic processing means 16 is an arithmetic processing device including a CPU, which controls the entire operation, calculates the position of the slit image of the dark field pattern 300, and calculates the corresponding tilt angle. .

In the first embodiment configured as described above,
When the tilt sensor 1000 is tilted, the free surface of the liquid member 600 is kept horizontal, so that the image of the dark field pattern 300 on the first light receiving element 810 and the second light receiving element 820 moves in proportion to the tilt angle. Will be.

Here, when the inclination sensor 1000 is inclined at the angle θ, as shown in FIG. 4, if the refractive index of the liquid member 600 is n, the light reflected from the free surface is inclined by 2nθ. Assuming that the distance on the linear sensor that is the first light receiving element 810 and the second light receiving element 820 is L,

L = f * tan (2nθ) Equation 1

## EQU10 ##

Therefore, the position of the image of the dark-field pattern 300 is detected by the first light receiving element 810 and the second light receiving element 820, the distance from the reference position is obtained, and the arithmetic processing means 16 converts the distance to the inclination angle. For example, the inclination θ of the inclination sensor 1000 can be measured.

Next, the calculation processing of the inclination angle by the calculation processing means 16 will be described in detail.

Regarding the tilt angle, the distance dL from the position of the detected pattern on the linear sensor may be measured by focusing on the position of the specific pattern.

For the distance equal to or smaller than the pitch interval, the output of the first light receiving element 810 and the second light receiving element 820 are subjected to Fourier transform to determine the phase difference φ between the pitch interval on the linear sensor and the reference position. Calculate,

Φ * p * m / (2π) Expression 2

By obtaining the distance, a distance less than the pitch interval can be measured with high accuracy. Here, m is a magnification.
Then, the total distance can be calculated by matching the distance with a distance equal to or longer than the pitch interval obtained from the distance of the specific pattern.

The arithmetic processing means 16 can calculate the corresponding tilt angle from the entire distance.

That is, a first light receiving element 810 for receiving an absolute pattern indicating a position in the Y direction condensed in the X direction at a pitch p, and a position in the X direction condensed in the Y direction at a pitch p And a second light receiving element 820 that can receive an absolute pattern indicating the following.
The inclination angle in the axial direction can be calculated by the arithmetic processing means 16.

It should be noted that if the area sensor is used without using the first light-collecting element 710 and the second light-collecting element 720 and the first light-receiving element 810 and the second light-receiving element 820, a dark field can be obtained. By using the pattern 300, it is possible to detect the inclination of two axes in the X direction and the Y direction.

Further, instead of the liquid member 600 having a free surface, a swingable suspension member can be used.

First, in order to simplify the explanation, the pattern formed in the dark field pattern 300 will be described in a simplified manner as shown in FIG. In this description, the pattern C will be omitted for easy understanding. That is, R, A (0), B (0), R, A (1), B
The case where (1), R, A (2), B (2),... Are repeatedly arranged will be described below.

In the pattern formed in the dark field pattern 300, as shown in FIG. 5, a first pattern A, a second pattern B, and a third pattern R are repeatedly arranged at equal intervals (p). . That is, each block is formed continuously as a set of three types of patterns, and the leftmost block is defined as 0 block, and R (0), A (0)
If described as (0), B (0), R (1), A (1),
B (1), R (2), A (2), B (2), ...
... are repeatedly arranged. Since all patterns are repeated at equal intervals p, a signal corresponding to this interval is used as a reference signal.

For example, the third pattern R has a black width of 5
The fixed width is 0 μm, and the first pattern A is 7 μm.
In the second pattern B, the width of the black portion is modulated such that one cycle is formed by five blocks, and the width of the black portion is modulated so that one block is formed by one cycle.

Next, the first pattern A is 1 in 7 blocks.
Since the width of the black portion is modulated so as to have a period, if the modulation width is 20 μm to 80 μm, the width D of the first pattern
_A is given by the following equation.

D _A = 50 + 30 * SIN (2 * π * X / 7) Equation 3

Is obtained. However, X = (0, 1, 2, 3,...
...).

[0104] Similarly, the second pattern B, since by modulating the width of the black portion as a one cycle in 5 blocks, the width D _B of the second pattern is given by the following equation.

D _B = 50 + 30 * SIN (2 * π * X / 5) Equation 4

The following is obtained. However, X = (0, 1, 2, 3,...
...).

Since the first pattern A and the second pattern B have slightly different periods, similar patterns appear at a distance that is the least common multiple of the two. In this embodiment, a similar pattern appears in 35 blocks, which is the least common multiple of 7 blocks and 5 blocks.

In other words, the phase number of the first pattern A in the block including the horizontal position is φ _A (0 to 6),
The phase number of the second pattern B at the horizontal position is φ
_B (0 to 4), the position H of the dark field pattern 300
Is

From the combination of φ _A and φ _B , from the block number φ _AB including each phase number,

H = φ _AB * p * m Equation 5

Is obtained.

Next, a method of calculating the position of the dark field pattern 300 will be specifically described.

First light receiving element 810 and second light receiving element 8
For the 20 output signals, the width of the pattern is determined within the range of the first and second half pitches of the reference signal (the signal corresponding to the equal pitch p). Further, if the width of this pattern is thinned out every three (product detection), a signal 1 corresponding to the first pattern A and a signal 2 corresponding to the second pattern B are obtained as shown in FIG.
And a signal 3 corresponding to the third pattern R is obtained.
However, the width of the third pattern R is not modulated and the maximum modulation width of the first pattern A and the second pattern B is 80 μm, whereas the third pattern R is only 50 μm. The width of the signal 3 corresponding to the pattern R is substantially constant, and is about 50% of the value of the signal 1 or the signal 2.

Since the third pattern R, the first pattern A, and the second pattern B are repeatedly arranged in a predetermined order, the decimated signal is output to the third pattern R.
The pattern R, the first pattern A, or the second pattern B can be determined.

Next, from the signals A and B, a set of signals A and B including the address position (the m-th bit) of the linear sensors 810 and 820 at the reference position for tilt reading is selected, and A and B are selected. By determining the phase number of the first pattern A, it is possible to determine at which position the combination of the first pattern A, the second pattern B, and the third pattern R is located.

Here, assume that the phase number of the A signal is Am,
The block number φ _AB including R, A, and B can be obtained from the combination of the phase numbers of A and B, where Bm is the phase number of the signal.

Then, the pattern including the reference position (m-th bit) is

In the case of the R pattern:... 3 * p * φ _AB ...

In the case of the pattern A,... P * (3 * φ _AB +1)...

In the case of the B pattern: p * (3 * φ _AB +2) Expression 8

Is obtained as follows. Here, p is a pitch.

By combining the values of Equations 6 to 8 with the values obtained from Equation 2, the dark field pattern 30
The position H of 0 can be obtained.

Next, the arithmetic processing means 16 of this embodiment will be described in detail with reference to FIG.

The amplifier 161 is connected to the first light receiving element 810 or the second light receiving element 82 selected by the selector 168.
The sample and hold 162 amplifies the electric signal from 0, and samples and holds the amplified electric signal with a timing signal from the clock driver 165. The A / D converter 163 performs A / D conversion of the sampled and held electric signal. The RAM 164 stores an A / D-converted digital signal. Microcomputer 1
66 is for performing various arithmetic processing.

Here, the function performed by the microcomputer 166 will be described with reference to FIG.
Are the reference signal forming unit 1661 and the pattern signal forming unit 1
662 and a calculating unit 1664, and the reference signal forming unit 1661 is provided with the first light receiving element 810 and the second light receiving element 861.
A reference signal corresponding to an equal pitch p is formed from the electric signal obtained from the step 20 by fast Fourier transform.

The pattern signal forming section 1662 obtains the width within the range of the first and second half pitches of the reference signal, and thins out this pattern width every three (product detection) to obtain the first signal.
And the second pattern signal.

The calculating section 1664 calculates the block number including the reference position from the phase numbers of the first pattern signal and the second pattern signal, further obtains the position of the pitch unit, and obtains the result by fast Fourier transform. The position of the dark-field pattern 300 is determined with high precision, and the movement amount H of the dark-field pattern 300 is determined.

The display 167 displays the tilt angle calculated by the calculation unit 1664, and may employ a display means such as a liquid crystal display, or may output a signal to an external storage means or the like. .

If an inclination sensor is attached to the electronic theodolite 20000 or the like as shown in FIGS. 10 and 11, it is possible to detect the inclination of the surveying apparatus main body in the X and Y directions.

[0130]

According to the present invention having the above-described structure, a first optical system for separating a dark-field pattern arranged in two-dimensional positions and separating light from the dark-field pattern into two directions is provided. A first light-condensing element for condensing light from the first optical system in a first direction, and a light from the first optical system different from the first direction. A second light-condensing element for converging light in a second direction, a first light-receiving element for receiving the pattern image condensed by the first light-condensing element, and a second light-receiving element. A second light receiving element for receiving the pattern image condensed by the light condensing element, and a position on the pattern based on light receiving signals of the first light condensing element and the second light condensing element. The dark field pattern includes the first light-collecting element and the second light-condensing element. Since it is formed from a two-dimensional pattern which is arranged at the same pitch with respect to the longitudinal direction of the light-collecting element and arranged so that the width of the pattern when viewed from the direction orthogonal thereto is the same, the mechanical strength And a highly accurate position measuring device can be provided, and a compact position measuring device can be provided.

Further, according to the present invention, if the light source and the surface of the liquid member having a free surface for reflecting the light from the light source are arranged in a conjugate relationship, the light source can be formed on the surface of the liquid member. This has the effect of minimizing the reflection area and minimizing the error due to the surface tension of the liquid. Further, the volume of the liquid member can be reduced.

Since the half mirror of the present invention has a surface inclined with respect to the transmitted light from the light source, the reflected light does not travel in the same optical path in the opposite direction. There is an effect that highly accurate measurement can be performed without being incident on the light receiving means.

[0133]

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a tilt sensor 1000 according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a dark field pattern 300 according to the present embodiment.

FIG. 3 is a diagram illustrating a dark field pattern 300 according to the present embodiment.

FIG. 4 is a diagram illustrating a fluid member according to the present embodiment.

FIG. 5 is a diagram illustrating the principle of measurement.

FIG. 6 is a diagram illustrating the principle of measurement.

FIG. 7 is a diagram illustrating the principle of measurement.

FIG. 8 is a diagram illustrating a configuration of an arithmetic processing unit according to the present embodiment.

FIG. 9 is a diagram illustrating a configuration of an arithmetic processing unit according to the present embodiment.

FIG. 10 is a diagram illustrating an example in which the present embodiment is applied to an electronic theodolite 20000.

FIG. 11 is a diagram illustrating an example in which the present embodiment is applied to an electronic theodolite 20000.

FIG. 12 is a diagram illustrating a conventional technique.

[Explanation of symbols]

 20000 Electronic theodolite 1000 Inclination sensor 100 Light source 200 Condenser lens 300 Dark field pattern 410 First pattern relay lens 420 Second pattern relay lens 510 First half mirror 520 Second half mirror 511 Semi-transmissive surface 512 Inclined surface 600 Liquid member having free surface 710 First cylindrical lens 720 Second cylindrical lens 810 First light receiving element 820 Second light receiving element 16 Arithmetic processing unit 166 Microcomputer 1 1661 Reference signal forming unit 1662 Pattern signal forming unit 1664 Calculation Department

Claims (15)

[Claims] 1. A dark-field pattern arranged to indicate a two-dimensional position, a first optical system for separating light from the dark-field pattern in two directions, and a first optical system. A first condensing element for condensing the light in a first direction, and condensing light from the first optical system in a second direction different from the first direction A second light-collecting element for causing the first light-receiving element to receive the pattern image condensed by the first light-collecting element;
A second light receiving element for receiving the pattern image condensed by the light condensing element, and a position on the pattern based on light receiving signals of the first light condensing element and the second light condensing element. The dark field pattern is disposed at an equal pitch with respect to the longitudinal direction of the first light-condensing element and the second light-condensing element, respectively.
In addition, a position measuring device formed of a two-dimensional pattern arranged so that the width of the pattern when viewed from the orthogonal direction is the same. 2. The position measuring apparatus according to claim 1, wherein the dark field pattern has a constant width in each of the first direction and the second direction and is sequentially arranged at an equal pitch. 3. The dark-field pattern includes a first pattern in which each of the first direction and the second direction is modulated at least in a first cycle, and a second pattern different from the first pattern. The position measuring device according to claim 1, further comprising a second pattern modulated at a period of (i), wherein the first pattern and the second pattern are sequentially arranged at an equal pitch. 4. The position measuring apparatus according to claim 3, wherein the modulation of the first pattern and the second pattern is performed by spatial modulation that changes a line width. 5. A light source, a first optical system for collimating light from the light source, and a two-dimensional position for passing light from the first optical system are arranged. A dark field pattern, a liquid member having a free surface for reflecting the dark field pattern, a second optical system for imaging the pattern reflected by the liquid member, and the second optical system A first light-condensing element for condensing light from the first direction in a first direction, and a first light-condensing element for condensing light from the second optical system in a second direction different from the first direction. 2, a first light receiving element for receiving the pattern image condensed by the first light condensing element, and a pattern light condensing by the second light condensing element. A second light receiving element for receiving light, and a light receiving signal of the first light collecting element and the second light collecting element A position measuring device for calculating an inclination from a position on the dark field pattern based on the dark field pattern, wherein the dark field pattern is formed from an absolute pattern. 6. The position measuring apparatus according to claim 5, wherein a half mirror is disposed on an optical path between the liquid member and the second optical system. 7. The light source and a surface of the liquid member having a free surface for reflecting light from the light source,
The position measuring device according to claim 5, wherein the position measuring device is arranged in a conjugate relationship. 8. The position measuring device according to claim 6, wherein the liquid member is formed integrally with the half mirror. 9. An arithmetic processing unit calculates a motion equal to or more than a pitch interval of a pattern by an absolute pattern, and obtains a motion equal to or less than a pitch interval of a pattern by calculating a phase of the pattern by Fourier transform to calculate a slope. The position measuring device according to any one of claims 5 to 8, wherein the position measuring device is configured to obtain the position. 10. Instead of a liquid member having a free surface,
The position measuring device according to any one of claims 5 to 9, wherein the position measuring device is a swingable suspension member. 11. The dark-field pattern comprises at least a first
A first pattern modulated by a first period and a second pattern modulated by a second period different from the first period;
The position measuring device according to any one of claims 5 to 10, wherein a pattern and the second pattern are sequentially arranged at an equal pitch. 12. The position measuring device according to claim 5, wherein the modulation of the first pattern and the second pattern is performed by spatial modulation that changes a line width. 13. A uniform third pattern is provided in addition to the first pattern and the second pattern, and the first pattern, the second pattern, and the third pattern are sequentially arranged at an equal pitch. The position measuring device according to claim 11, wherein the position measuring device is configured. 14. The device according to claim 1, wherein at least one area sensor is used in place of the first light-collecting element and the second light-collecting element, and the first light-receiving element and the second light-receiving element. A position measuring device according to any one of the preceding claims. 15. A surveying instrument using any one of the position measuring devices according to claim 1, which is attached to the surveying instrument body and detects an inclination of the surveying instrument body.