JP3239095B2 - Relative displacement measuring device, position measuring device, and posture control device for moving body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative displacement measuring device and a position measuring device, and more particularly, to a device for measuring the relative displacement of a first moving body and a second moving body that move together with high accuracy.

[0002]

2. Description of the Related Art A lightwave interferometer using laser light is known as a length measuring device. In principle, the length measurement accuracy reaches 10 ^-8 (m) to 10 ^-11 (m), and therefore, the lightwave interferometer is an indispensable device for high-precision length measurement. However, if measurement is performed in air using such a light wave interferometer, the measurement accuracy will be degraded due to wavelength fluctuations due to fluctuations in the refractive index of air. For example, even when the total length of the measurement optical path is 1 mm or less, a variation of about ± 5 nm occurs in standard deviation. In addition, the fluctuation increases as the total length of the measurement optical path increases. For example, when the total length of the optical path length is 1 m, the fluctuation due to the fluctuation becomes about ± 100 nm.

Further, when an object has a motion, the motion of the air is caused by the effect of the motion, and as a result, the refractive index of the air on the measurement optical path fluctuates greatly. For example, when an object reciprocates at a low speed of 0.25 μm at a cycle of 1 second, it is reported that the error of the output of the light wave interferometer exceeds ± 50 nm.

Therefore, when measuring the distance between objects or the displacement of an object using an optical interferometer in the air, the above-described error occurs, so that there is a problem that high-accuracy measurement cannot be realized.

Therefore, it has been proposed to cancel the above-mentioned fluctuation of the refractive index by using two light waves having different wavelengths. However, even with this method, for a measurement optical path length of about 500 mm, when the object is stationary, ± 5n
It is a practical limit to suppress the fluctuation width to about m.

On the other hand, Japanese Patent Application Laid-Open No. Hei 8-166215 discloses that the entire measurement system is housed in a bellows whose inside is evacuated, and the length of an object to be measured (in air) outside the bellows is measured. An apparatus is disclosed. However, there is a problem in that the variable range of the length is limited by the bellows structural constraints.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to accurately measure the displacement (or position) of a moving object placed in the air or an environment identified with the same. Is to do.

Another object of the present invention is to measure the displacement of the above-mentioned moving object with the same accuracy as that of the light wave interferometer in a vacuum.

It is a further object of the present invention to realize a displacement measurement that does not have much restriction on the measurable range.

[0010]

In order to achieve the above object, the present invention relates to an apparatus for measuring the relative displacement of a first moving body and a second moving body which run in parallel with each other, wherein the first moving body is provided. Above, the first provided with a predetermined angular relationship
And a second relay reflector, and on the second moving body,
First and second terminal reflecting mirrors arranged orthogonally to the reflection optical axes exiting from the first and second relay reflecting mirrors, and the first terminal reflecting mirror via the first relay reflecting mirror Between the first measuring instrument for measuring the length of the first measuring optical path and the second terminal reflecting mirror via the second relay reflecting mirror. A second length measuring device for transmitting and receiving a wave to measure a length of a second measuring optical path, and the first moving body based on an output change of the first length measuring device and an output change of the second length measuring device before and after exercise. And calculating means for calculating the relative displacement of the second moving body.

According to the above configuration, the first moving body provided with the first and second relay reflectors and the second moving body provided with the first and second terminal reflecting mirrors run in parallel, and the two move between the two. Is calculated. That is, the change in the first measurement optical path before and after the exercise is measured by the first length measuring instrument, while the change in the second measurement optical path before and after the exercise is measured by the second length measuring instrument, and the main motion is determined by a predetermined calculation based on those changes. A displacement in a direction along the direction is determined. In this case, even if there is a motion component orthogonal to the main motion direction, it is canceled by the predetermined calculation. In other words, the angles of the first and second relay reflecting mirrors are set so that such displacement calculation is realized.

Here, the first length measuring device and the second length measuring device are preferably light wave interferometers utilizing laser light.
If the position of the first moving body is known, the position of the second moving body may be calculated from the obtained relative displacement. Also,
The concept of the relay mirror and the terminating mirror includes various means for reflecting light (for example, a corner cube). First
The length measuring device and the second length measuring device are desirably provided such that an optical axis exiting therefrom is parallel to the movement direction of the first moving body. In this case, the first length measuring device and the second length measuring device are desirably set. They are fixedly arranged on the same side as viewed from the first moving body. However, as long as the displacement calculation condition can be satisfied, the first length measuring device and the second length measuring device may be fixedly arranged on both sides of the first moving body.

In a preferred aspect of the present invention, a reference optical axis from the first length measuring device and the second length measuring device is set in parallel with a main movement direction of the first moving body and the second moving body.
Wherein the first relay reflector is provided at an angle of α with respect to the reference optical axis, and the second relay reflector is provided at an angle of π / 2-α with respect to the reference optical axis. Features.

As will be proved mathematically later, if the relay reflector is provided under the above-described angle condition, the displacement in the main movement direction alone is obtained by canceling the displacement of the movement orthogonal to the main movement direction. be able to. As α, for example, π / 6
Is desirable.

In a preferred aspect of the present invention, the calculating means calculates a difference between an output change of the first length measuring device and an output change of the second length measuring device before and after exercise.

That is, if the difference between the output changes of the two length measuring instruments is obtained under the above angle conditions, the relative displacement along the main motion direction can be obtained as a result.

In a preferred aspect of the present invention, the first moving body, the first and second relay reflectors, and the first and second length measuring instruments are accommodated in a first space, and the second moving body and The first and second terminal reflecting mirrors are accommodated in a second space, and the first space and the second space are separated from each other by a partition having optical transparency. .

Preferably, the first space is evacuated, or the first space has less fluctuation in the refractive index of light than the second gas contained in the second space. A gas (eg, helium) is filled. Preferably,
The second gas is air or a gas having a composition similar to air.
That is, according to the above configuration, it is possible to detect the position of the second object in the air or under the same environment as that in the vacuum or under the same measurement accuracy conditions.

In a preferred aspect of the present invention, a transparent body is inserted in a part or all of a gap between the first and second terminal reflecting mirrors and the partition. In a desirable mode of the present invention, a steady flow forming means for forming a steady flow (laminar flow) of gas in a part or all of a gap between the first and second terminal reflecting mirrors and the partition wall is included. It is characterized by the following.

That is, since the fluctuation of the refractive index easily occurs in the second space due to the influence of the gas, the length of light passing through the gas existing inside the second space is made as short as possible.
Alternatively, a steady state is forcibly formed to suppress wavelength fluctuation.

In a preferred aspect of the present invention, the optical axis exiting from the first and second relay reflectors is formed by the partition wall and the first relay reflector.
And intersect or approach in a gap between the second terminal reflector and the second terminal reflector. According to such a configuration, the distance between the two optical axes in the second space can be made equal, and as a result, the influence of fluctuation can be canceled as a result in the displacement calculation.

In a preferred aspect of the present invention, the first moving body is housed in a vacuum vessel, and is driven and controlled by an external magnetic action. In other words, the first moving body is driven and controlled using magnetic levitation or magnetic attraction. In this case, if the second moving body is provided with magnetic action means, it is interlocked with the movement of the second moving body. The first moving body can be driven to follow without contact. If the position of the first moving body is controlled so that the relative displacement becomes zero, the position of the second moving body can always be matched with the position of the first moving body, and as a result, the second moving body Can be measured as the position of the first moving body.

That is, the position measuring device according to the present invention comprises:
The relative displacement measuring device, a follow-up control mechanism that controls the position of the first moving body by following the movement of the second moving body so that the relative displacement becomes zero, and the position of the second moving body. And a position measuring unit that measures the position of the first moving body.

Also, the present invention is an apparatus for controlling the posture of a first moving body and a second moving body, wherein the first light wave interferometer for measuring the posture of the first moving body and the first light wave interference First control means for controlling the posture of the first moving body to move in parallel to a predetermined reference axis based on the measurement result of the meter, and provided with a predetermined angular relationship on the first moving body. A first moving body reflecting mirror provided on the second moving body, a second moving body reflecting mirror provided on the second moving body at a predetermined angular relationship with respect to a reflection optical axis emitted from the first reflecting mirror, A second light wave interferometer for measuring a posture of the second moving body based on reflected light from the moving body reflecting mirror and the second moving body reflecting mirror; and a second light wave interferometer based on a measurement result of the second light wave interferometer. Controlling the posture of the moving body to move in parallel with the first moving body; And having a second controller.

Here, the first moving body is preferably housed in a space that is substantially in a vacuum state, or the first moving body has less fluctuation of the refractive index of light than air. It is preferable that the gas is accommodated in the charged space.

Further, the first moving body and the second moving body are separated from each other by a partition, and the partition on an optical path between the first moving body reflecting mirror and the second moving body reflecting mirror is: It is preferable to be composed of a transparent body.

In the present invention, a magnet is provided on the first moving body, and an electromagnet is provided on the second moving body so as to face the magnet. The first moving body is driven in a non-contact manner by magnetic interaction. Thus, for example, the yaw angle and the pitch angle of the first moving body can be controlled in a non-contact manner.

Here, a tow magnet is further provided on the first moving body, and a tow electromagnet is further provided on the second moving body so as to face the tow magnet. It is preferable that the first moving body is made to follow the second moving body by a magnetic attraction force between a tow magnet and the tow electromagnet.

It is preferable that at least one of the first control means and the second control means controls at least one of a yaw angle and a pitch angle of the first moving body or the second moving body. Further, at least one of the first control means and the second control means,
It is preferable to control sliding in a direction orthogonal to the movement direction of the first moving body or the second moving body. For this purpose, at least one of the first control means and the second control means is provided with the first moving body or the second control means.
It is desirable that the control is performed based on the postures detected by the length measuring system in the vertical direction and the length measuring system in the horizontal direction with respect to the moving direction of the moving body.

[0030]

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

FIG. 1 shows the principle of a relative displacement measuring device according to the present invention. The light wave interferometer 10 is a device that is fixedly arranged, transmits and receives laser light as a light wave, and measures a change in an optical path length based on laser interference. The first moving body is provided with a mirror M for reflecting a laser beam, while the second moving body is provided with a mirror N for reflecting a laser. The mirror M moves in response to the movement of the first moving body, which is indicated by M ₁ , M ₂ , and M ₃ . Similarly, the mirror N is moved according to the movement of the second moving body.
Also exercise, the movement is indicated by _{N 1, N 2, N 3} .

In FIG. 1, the origin of the measurement optical path is indicated by O, and the reflection point on the mirror M is indicated by P. If the mirror M is exercised as described above, the reflection point P moves to the P ₁ of P _3. The mirror M is fixedly arranged on the first moving body at an angle θ with respect to the optical axis emerging from the origin O. That is, the angle θ formed between the mirror M and the optical axis emerging from the origin O is not changed by the movement of the first moving body. In other words, the posture of the first moving body is controlled so that θ is constant.

Incidentally, the movement vector of the mirror M from M ₁ to M ₂ is represented by c, and the movement vector from M ₂ to M ₃ is d.
It is represented by A composite vector related to the movement of the mirror M is represented by a thick arrow.

The mirror N is provided perpendicularly to the optical axis emitted from the reflection point on the mirror M. That is,
Even if the mirror N moves with the movement of the second moving body, the attitude of the mirror N is controlled so as to be always perpendicular to the mirror M.

Incidentally, the movement vector of the mirror M from N ₁ to N ₂ is indicated by a, and the movement vector of the mirror N from N ₂ to N ₃ is indicated by b. Reflection point of the laser beam on the mirror N varies as a to Q ₁ Q _3. A composite vector relating to the movement of the mirror N is indicated by a thick arrow.

Here, the mirror M moves from M ₁ to M ₃ ,
This together with the mirror N to consider measurement optical path entire displacement in the case where motion from N ₁ to N _3.

First, the decrease in the optical path length due to the change in the position of the mirror M is expressed as follows from the geometric relationship shown in FIG.

[0038]

[Number 1] of the optical path length decrease _{= P 3 P 1 + P 1} P 4 = c + d / tanθ + (c + d / tanθ) · (-cos2θ) = (c + d / tanθ) · (1-cos2θ) ··· (1) whereas The increase in the optical path length due to the change in the position of the mirror N is expressed as follows.

[0039]

[Number 2] increased light path length _{= Q 1 Q 4 = a ·} (-cos2θ) + b · sin2θ ··· (2) Thus, the measurement optical path before and after exercise in view of the both increase and decrease of the optical path length Considering the increase or decrease of the optical path length of the first observable quantity f observed by the lightwave interferometer 10
(Θ) is expressed as follows.

[0040]

F (θ) = {− a · cos2θ + b · sin2θ} − {(c + d / tanθ) · (1−cos2θ)} = − c− (ac) · cos2θ + (b−d) · sin2θ (3) In FIG. 1, the main motion directions of the first moving body and the second moving body are parallel to the optical axis emerging from the origin O. The value to be obtained as the relative displacement is ac. Therefore, in order to obtain the relative displacement ac without being affected by the movement vectors d and b, two observation systems are used in the present invention, as described later with reference to FIG. The first observation system is, for example, an observation system as shown in FIG. 1, that is, an observation system in which the mirror M is arranged while being tilted by θ with respect to the optical axis. The other observation system has the same basic configuration as that shown in FIG. 1, but is an observation system provided with a mirror M tilted by π / 2−θ. Incidentally, in any observation system, it is a condition that the mirror N is arranged orthogonal to the optical axis emitted from the mirror M.

In the above equation (3), instead of θ, π
By substituting / 2-θ, the second observable quantity f (π / 2−θ) obtained by the second observation system is expressed as follows.

[0042]

F (π / 2−θ) = − c + (ac) · cos 2θ + (b−d) · sin 2θ (4) Here, considering the properties of sin and cos, When the difference between the first observable quantity f (θ) and the second observable quantity f (π / 2−θ) is calculated, only the term relating to a−c that is ultimately obtained remains. That is, the following relative displacement a
-C can be obtained.

[0043]

-F (θ) + f (π / 2−θ) = 2 (ac) · cos2θ ac = {− f (θ) + f (π / 2−θ)} / 2cos2θ (5) As described above, by setting the inclination of the mirror M in the two observation systems in a predetermined relationship, as will be described later with reference to FIG. 2, it is possible to easily obtain only the relative displacement as a result. is there.

Incidentally, in FIG. 2, as an example, θ
= Π / 3 (= 60 degrees) is shown. Under these conditions,

Equation 6: a−c = −f (π / 3) + f (π / 2−π / 3) = f (π / 6) −f (π / 3) (6) Displacement (a-
c) can be calculated.

FIG. 2 shows a schematic configuration of a position measuring apparatus to which the above-described principle of measuring the relative displacement is applied.

The first moving body 12 is accommodated in the first space 14. The first space 14 is, for example, a vacuum space. Of course, the first space 14 can be constituted by a gas which is less affected by the fluctuation of the wavelength as described above. Two mirrors M ₂ and M ₃ are fixedly arranged on the first moving body 12. The mirror M ₂ is connected to the second lightwave interferometer 10.
It is arranged while being inclined by π / 6 with respect to the optical axis 102A exiting from B. Mirror M ₃ is the first lightwave interferometer 10A
It is arranged while being tilted by π / 3 with respect to the optical axis 100A that exits.

On the other hand, the second moving body 16 is housed in the second space 18. The second space 18 is, for example, a space in the atmosphere. Two mirrors M ₄ and M ₅ are fixedly arranged on the second moving body 16. In this case, the mirror M ₄ is
Are arranged perpendicularly to the optical axis 100B emanating from the mirror M _3, [pi respect the direction of movement of the first movement member 12 and the second movement body 16 (parallel with the optical axis 100A and the optical axis 102A)
/ 6. On the other hand, mirror M
₅ is orthogonally disposed with respect to the optical axis 102B emanating from the mirror M _2, specifically, as illustrated with respect to the direction of movement π
/ 6.

[0048] As apparent from the above description, the laser beam exiting from the first light wave interferometer 10A is reflected by the mirror M _3, after being further reflected by the mirror M _4, first it is reflected by the mirror M ₃ again Light wave interferometer 10
A wave is received. Similarly, the second lightwave interferometer 10
The laser beam emitted from B is reflected by the mirror M ₂ , further reflected by the mirror M ₅ , and then returned to the mirror M ₂ again.
And is received by the second lightwave interferometer 10B.

In FIG. 2, the first measurement optical path 100 includes an optical axis 100A and an optical axis 100B.
Reference numeral 02 includes optical axes 102A and 102B.

The first space 14 and the second space 18 are formed by partition walls 20.
Is divided by The portion of the partition wall 20 through which the laser beam passes is made of a member having optical transparency, for example, a glass plate. Of course, the portion of the partition wall 20 may be a hollow container, and the inside thereof may be filled with a gas that does not cause fluctuation of the refractive index. The first space 14 is formed inside a container (not shown), while the second space 18 may be formed inside the container, but may be open to the atmosphere.

The third light wave interferometer 22 is means for measuring the position of the first moving body 12 in the direction of movement. The first moving body 12 is provided with a mirror M _1.
Laser light emitted from is reflected by the mirror M _1. Thus, the distance or the displacement of the first moving body 12 in the moving direction is measured by using the interference of the laser light.

The position / posture control unit 24 is means for controlling the position of the first moving body 12 in the moving direction and controlling the posture of the first moving body 12. In this case, for example, the attitude control may be performed using the output of the third light wave interferometer 22. By always maintaining a constant orientation of the first movement member 12, it is possible to always meet the angle conditions of the respective mirrors M ₂ and M ₃ as described above. As will be described later, the position / posture control unit 24 also has a function of controlling the position of the first moving body 12 so that the relative displacement is always zero as needed. However, in the case where an automatic mechanism is provided so that the position of the first moving body 12 is always the same as the position of the second moving body 16, electrical control is not necessarily required.

The relative displacement calculator 26 is provided with the first light wave interferometer 1
This is a means for calculating the relative displacement by executing the calculation of the above-described equation (6) based on the signals output from 0A and the second lightwave interferometer 10B. That is, the first moving body 12 and the second
Each light wave interferometer 10A, 1 before and after the movement of the moving body 16
The difference of the output change of 0B is calculated, and thereby the relative displacement is calculated.

The main control section 27 controls the entire operation of the present apparatus. In particular, when the relative displacement becomes zero, the first control section 27 performs the first control.
It has a function of outputting the position of the moving body assuming it as the position of the second moving body. Further, the main control unit 27 includes the position and orientation control unit 2.
4 so that the relative displacement becomes zero.
It also has the function of controlling the position of No. 2. The first
If the position and the relative displacement of the moving body 12 are specified, even if the positions of the first moving body 12 and the second moving body 16 do not always match, as a result, the position of the second moving body 16 can be accurately determined. Can be calculated.

As described above, since the second space 18 is formed in the atmosphere, the optical path length of the laser beam passing through the second space 18 is preferably as short as possible. Therefore, in the apparatus of the present embodiment, the following fluctuation reducing measures are taken. A member 28 made of, for example, glass is provided in a gap between the mirrors M ₄ and M ₅ and the partition wall 20. With this member 28, the distance that the laser light passes through the air can be made as short as possible, and as a result, deterioration of the measurement accuracy due to fluctuation of the refractive index can be prevented. The member 28 includes a mirror M ₄ ,
The cross section in accordance with the opening of M ₅ is formed into a triangular shape, not necessarily limited to this shape.

Further, a high-speed air flow may be forcibly injected into all or a part of the space between the mirrors M ₄ and M ₅ and the partition wall 20 to form a stable laminar flow in the gap. Even with such a laminar flow, it is possible to suppress the influence of air fluctuation. FIG.
Is a means for forming such a high-speed airflow. Such a laminar flow may be utilized in combination with member 28 as shown.

In the above algorithm,
As a result, since the difference between the observable amounts is calculated, the influence of the fluctuation of the refractive index at the same location tends to be canceled. Therefore, if the distances at which the lasers pass through the air in the second space 18 are made equal, as a result, the influence of air fluctuations can be reduced. As a configuration for this purpose, in the present embodiment, the optical axis 100B and the optical axis 102B intersect in the gap between the partition wall 20 and the member 28.

The attitude control section 32 is means for controlling the attitude of the second moving body 16, and as described above,
The attitude of the second moving body 16 is controlled so that the mirrors M ₄ and M ₅ are orthogonal to B and 102B.

As described above, in this embodiment, moving the first moving body 12 in the first space substantially in a vacuum state and the second moving body in the atmosphere in parallel is a prerequisite for relative displacement detection. Satisfying such prerequisites is not only in the case of detecting relative displacement, but also, for example, by mounting various measuring devices on the second moving body 16 and mounting the second moving body on a predetermined position. This is essentially important for a posture control device that moves in parallel with a reference (the first moving body or a laser optical axis serving as a reference for the first moving body).

In this embodiment, it is the third light wave interferometer 22 that detects the posture of the first moving body (when the posture variation is, for example, about 10 μrad in yaw angle, about 1/10 μrad). This third measurement
Based on the detection result from the light wave interferometer 22, the position / posture control unit 24 controls the posture of the first moving body 12 so as to move in parallel with the laser optical axis (optical axis 100A). The physical quantities to be controlled include the yaw angle and the pitch angle described above.

On the other hand, the posture of the second moving body 16 is
This is performed by controlling the mirrors M ₄ and M _{5 to} be orthogonal to 00B and 102B. Specifically, the second moving body 16 is provided by the first lightwave interferometer 10A and the second lightwave interferometer 10B.
The posture control unit 32 controls the posture of the second moving body 16 on the basis of the detection result to be parallel to the first moving body (that is, parallel to the laser optical axis). )
Exercise.

Thus, the second moving body 16 in the atmosphere can be caused to linearly move in accordance with a predetermined reference with an accuracy close to the straightness of the laser beam in a vacuum.

The second moving body 16 is moved in parallel to the first moving body 12 (in other words, the second moving body 16
In order to make the moving body 16 linearly move with high precision according to a predetermined standard), the mirrors M ₂ , M ₃ ,
M ₄ and M ₅ are not necessarily required. One mirror is provided on the first moving body 12 at a predetermined angle with respect to the laser optical axis, and another mirror is provided on the second moving body 16.
The laser beam from the light wave interferometer in a vacuum is the first moving body 1
After being reflected by the mirror on the second moving body and perpendicularly incident on the mirror on the second moving body, further reflected by the mirror on the second moving body 16, the mirror returns to the mirror on the first moving body 12, and finally This is also possible by forming an optical path that returns to the light wave interferometer. Of course, also in this case, the first moving body 12
It goes without saying that the member of the partition wall 20 located on the optical path between the upper mirror and the mirror on the second moving body 16 needs to be a transparent window. Then, the posture of the second moving body 16 can be measured by detecting the laser beam reflected by the mirror on the first moving body 12 and the mirror on the second moving body and returned by the light wave interferometer. (Most of the light path is the first
Since it is in the vacuum space where the moving body 12 is located, it can be measured with a resolution of about 1/10 μrad similarly to the posture measurement of the first moving body 12), and based on this, the posture control unit 32 By controlling the yaw angle, the pitch angle and the like of the first moving body 12, the moving body can be moved in parallel with the first moving body 12.

Next, a specific embodiment of the position measuring device will be described with reference to FIG.

The first moving body 12 and the second moving body 1 described above
The guide mechanism 6 and the driving mechanism 6 are indispensable for the movement. Since the second moving body 16 is a movement in the air, for example, a mechanism used in a normal high-precision machine tool or the like can be used as it is. On the other hand, with respect to the first moving body 12, it is necessary to realize high-precision movement in a vacuum, and with a normal contact-type guide mechanism, for example, there is a concern about problems such as lubrication suitable for a vacuum. On the other hand, a non-contact type guide mechanism such as a magnetic levitation mechanism or a non-contact linear motor, which is found in a conventional apparatus, can be used for the first moving body 12. In the present embodiment, a simple system as shown in FIG. 3 is employed.

In FIG. 3, the first moving body 12 and the second moving body 16 move in a direction perpendicular to the paper. The partition (shell) 20 that accommodates the first moving body 12 includes a support mechanism 34.
Supported by On the other hand, the second moving body 16 is fixed to the measured object, but the measured object is not shown. Of course, the second moving body 16 may be used as it is as a scaler.

The partition 20 has a window 20 through which the laser beam passes.
A is provided. The inside of the partition 20 is evacuated by a vacuum device (not shown).

The above-mentioned first moving body 12 is provided in the partition wall 20 so as to be movable along the moving direction.
An optical system 36 is provided. This first optical system is shown in FIG.
The mirrors M ₂ and M ₃ shown in FIG. As shown, the first moving body 12 is driven in non-contact with the partition wall 20. Therefore, the up / down control unit 200 and the left / right control unit 2
02 is provided. These up / down control unit 200 and left / right control unit 202 correspond to the position / posture control unit 24 shown in FIG. The vertical control unit 200 is the second moving body 1
6, a magnetic circuit component 38 fixed to the first moving body 12, and an excitation control coil 42 for exciting the magnetic circuit component 38. . On the other hand, the left / right control unit 202
Magnetic circuit component 44 fixedly arranged on second moving body 16
And a magnetic circuit component 46 fixed to the first moving body 12 and an excitation control coil 48 for exciting the magnetic circuit component 44. Further, the vertical control unit 2
A magnetic sensor 50 is provided for detecting the excitation effect of the right and left 00, and a magnetic sensor 52 is provided for detecting the magnetic operation of the left and right control unit 202.

Excitation is controlled by the up / down control unit 200 and the left / right control unit 202 based on the outputs of the magnetic sensors 50 and 52. As a result, the attitude of the first moving body 12 is always controlled to be constant. That is, a stable state is established without contact with the partition wall 20.

The second moving body 16 is provided with a second optical system 37. The second optical system 37 includes the mirrors M ₄ and M ₅ shown in FIG. That is, the laser light travels between the first optical system 36 and the second optical system 37 via the window 20A.

Although not shown in FIG. 3, the first moving body 1
By controlling the position of the second moving body 16 in the movement direction by, for example, a magnetic force, the positions of the second moving body 16 and the first moving body 12 in the movement direction can always be matched. That is, the relative displacement can be made to converge to zero. This is performed by the operation of the main control unit 27 shown in FIG.

According to the embodiment shown in FIG. 3, when the second moving body 16 moves, the relative displacement between the second moving body 16 and the first moving body 12 is always detected by the measuring mechanism described above, and the relative displacement is further detected. Is controlled to be 0. Since the position of the first moving body 12 can be measured with high accuracy under vacuum conditions, as a result, the position of the second moving body 16 can be measured with high accuracy as the position of the first moving body 12. In other words, the second in the air
The position of the moving body 16 can be observed with the same accuracy as the observation in a vacuum. Therefore, high-precision position measurement can be realized by making full use of the function of the lightwave interferometer.

The apparatus as shown in FIG. 3 can be used, for example, in the field of a high-precision processing apparatus or a semiconductor manufacturing apparatus.

FIG. 4 shows a more detailed configuration of the position measuring device shown in FIG. In the first moving body 12,
Two sets of up / down control magnetic circuit components 40 and left / right control magnetic circuit components 46 are provided. These magnetic circuit components can usually be constituted by permanent magnets or the like.
Also, the second moving body 16 is provided with an up / down control magnetic circuit component 38 and a left / right control magnetic circuit component 44 so as to face the magnetic circuit components 40 and 46 on the first moving body 12.
A set is provided, and these can be usually constituted by an electromagnet. An excitation control coil 42 is connected to the up / down control magnetic circuit component 38, and an excitation control coil 48 is connected to the left / right control magnetic circuit component 44, so that the current supplied to the excitation coils 42, 48 can be controlled. Thus, the magnetic force of the up / down control magnetic circuit component 38 and the left / right control magnetic circuit component 44 can be controlled.

Magnetic sensors 50 and 52 are provided at the end of the up / down control magnetic circuit component 38 and at the end of the left / right control magnetic circuit component 46, respectively. The magnetic force of the left / right control magnetic circuit component 44, specifically, the magnetic flux density between the electromagnet and the permanent magnet is detected.

As described above, the up / down control magnetic circuit component 40 and the left / right control magnetic circuit component 46 on the first moving body 12 and the up / down control magnetic circuit component 38 on the second moving body 16 opposed thereto. And two sets of left and right magnetic circuit components 44 (A and B in the figure) are provided, and two sets of A and B upper and lower control magnetic circuit components 38 on the second moving body 16 are provided.
The magnetic force acts on the first moving body 12 in a direction in which the first moving body 12 is attracted to each other (vertical direction in the drawing), so that the first moving body 12 floats without contact. On the other hand, A, B provided on the second moving body 16
The two sets of left and right control magnetic circuits 44 exert magnetic forces in directions (left and right directions in the drawing) that repel each other with the first moving body 12,
The first moving body 12 is located at the center position.

Further, the yaw angle and the pitch angle of the first moving body 12 are constantly measured by the third
The attitude control unit 24 controls the up / down control magnetic circuit component 40 and the left / right control magnetic circuit component 46 to correct the yaw angle and the pitch angle of the first moving body 12.

On the other hand, the first moving body 12 is further provided with a permanent magnet 72 and a permanent magnet 74 on a non-magnetic base 70, and the second moving body 16 is further provided with a non-magnetic base 6
Electromagnets 62 and 78 are provided on 0 and 76. The electromagnet 62 includes an excitation control coil 64 and a magnetic sensor 6.
6 and 68 are provided, and the electromagnet 78 has an excitation control coil 8
0 and magnetic sensors 82 and 84 are provided. These function as a traction control magnetic circuit 300, and the second moving body 16 pulls the first moving body 12 through the partition wall 20. For this reason, the magnetic sensors 66 and 68 are arranged not at the center of the magnetic pole of the electromagnet 62 but at a position shifted by a predetermined amount. The outputs of the two magnetic sensors 66 and 68 are compared, and the excitation control coil is set so that the difference becomes small. The position of the first moving body 12 can be towed without significantly deviating from the position of the second moving body 16 by controlling the current supplied to the second moving body 64. By this traction control, the first moving body 12 moves following the movement of the second moving body 16.

FIG. 5 is a block diagram of an electric system of the position measuring device shown in FIG. The position, yaw angle, and pitch angle of the first moving body 12 detected by the third light wave interferometer 22 as a three-axis interferometer are supplied to the attitude control unit 24.
Further, two sets of magnetic sensors 5 of A and B in the vertical control magnetic circuit.
The magnetic force (magnetic flux density) of the vertical control magnetic circuit element detected at 0 is amplified by the amplifier and then supplied to the attitude control unit 24. The magnetic force (magnetic flux density) of the left and right control magnetic circuit components detected by the two sets of magnetic sensors 52 in the left and right control magnetic circuit is amplified by an amplifier, and then supplied to the attitude control unit 24. The magnetic flux density detected by the magnetic sensors 66, 68, 82, 84 in the traction control magnetic circuit is supplied to the attitude control unit 24 after being amplified by the amplifier.

The attitude control unit 24 determines that the input yaw angle or pitch angle of the first moving body 12 is a desired value, specifically, the first moving body 12 moves parallel to the optical axis of the laser beam. Then, the respective excitation coils of the up / down control magnetic circuit, the left / right control magnetic circuit, and the traction control magnetic circuit are driven via a driver.
Note that such a closed-loop control system can be easily configured by a known servo technique.

Here, the correction of the yaw angle is performed by using the repulsive force of the magnet as described above. Specifically, as shown in FIG. 6, the left / right control magnetic circuit on the first moving body 12 side is used. A predetermined amount of offset is given to the component 46, and the second
The positive / negative angle adjustment may be performed according to the magnitude of the magnetic force of the left / right control magnetic circuit on the moving body 16. In the figure, the solid line indicates the posture of the first moving body 12 when the magnetic force of the left and right control magnetic circuit is weak, and the broken line indicates the posture when the magnetic force of the left and right magnetic circuit is strong. Thus, the yaw angle of the first moving body 12 can be controlled by increasing or decreasing the magnetic force.

As shown in the figure, when simultaneously controlling a pair of left and right control magnetic circuit components 46 on the left and right sides, 1
Twice the correction amount d per set is corrected. When the yaw angle is α and the distance between the two sets of left and right control magnetic circuit components is L,

Cos α = (L / (L ² + 4d ² )) (7)

D = 1/2 {L (1 / cos α−L)} ^0.5 (8) When the yaw angle α is obtained, the left-right direction correction amount d can be calculated. Similarly, the vertical correction amount can be calculated from the pitch angle.

Although the position measuring device of this embodiment has been described above, this position measuring device has no control function in the rolling direction, but the upper part of the first moving body 12 is pulled up by the up-down control magnetic circuit, and 1 moving body 1
By positioning the lower part of 2 at the center by the left and right control magnetic circuit, the function of stopping rotation of the first moving body 12 is also used. Therefore, the control of the rolling direction is also substantially possible.

In this embodiment, the floating of the first moving body 12 is detected from the magnetic flux density using a magnetic sensor. However, instead of the magnetic sensor, an electrostatic dose gap sensor or a laser type indicator is used. By using this, the floating amount of the first moving body 12 can also be detected. In particular, when a laser-type indicator is used, the window 20
It is preferable to measure from above the second moving body 16 through A.

The total output of the first moving body 12 is small,
On the other hand, if the magnet can provide a magnetic traction force sufficiently higher than the required traction force within the predetermined applied acceleration range, the excitation control coil and magnetic sensor can be removed and a simple fixed magnet can be used. is there.

The electromagnet 62, the permanent magnets 72, 74, and the electromagnet 78 of the traction control magnetic circuit element 300 may be independent of each other, or may be a part of an integral structure around the entire circumference as shown in FIG. Is also good.

Further, the magnetic circuits A, B, and C in FIG.
The distance between the magnetic circuits can be set to be sufficiently large so that the magnetic resistance between these magnetic circuits is sufficiently large, or a magnetic shielding means can be provided to prevent mutual magnetic interference and improve controllability.

As described above, high-precision measurement can be performed by controlling the yaw angle and the pitch angle of the moving body. On the other hand, as shown in FIG. If the guide rail that guides the body 12 (or the second moving body 16) has large rattling or undulation, the laser beam is adjusted as shown in FIG. 8B after adjusting the yaw angle and the pitch angle. A component in which the first moving body 12 (or the second moving body 16) slides in a direction orthogonal to the measurement optical path 100 (the moving direction of the moving body), which is the axis, may be maintained. That is, the traveling direction of the moving body travels exactly parallel to the measurement optical path 100 at any given moment, but the so-called meandering may not occur along the measurement optical path 100 as a whole. Further, the fluctuation of the yaw angle and the pitch angle is a slight movement, but there is a possibility that the meandering is largely generated.

Such a slide of the moving body can be eliminated by using the means for controlling the posture and the measurement by the light wave interferometer described above.

FIGS. 9A and 9B show an example of a posture variation detecting means using a light wave interferometer for detecting the sliding of the first moving body 12. FIG. 9A and 9B show an example in which three length measurement systems are provided as a posture variation detection unit for the first moving body 12. FIG.

First, the first is a traveling direction light wave interferometer 150 (this is a third light wave interferometer 22) disposed in the first space 14.
And a mirror 152 fixed on the first moving body 12 (which can also be used as the mirror M1) is a first length measuring system forming a first optical axis. . By measuring the optical path length by the first length measuring system, the accurate moving amount of the first moving body 12 in the moving direction is measured.

Second, a left-right optical interferometer 154 arranged in the first space 14 and a mirror 156 fixed on the first moving body 12 at 45 ° to the moving direction and arranged in parallel with the moving direction. A second length measurement system that forms the second optical axis with the mirror 158 that has been set. Table 52 by this second length measurement system
By measuring the optical path length including the left-right direction (vertical direction in the drawing), the sliding amount in the left-right direction with respect to the moving direction of the first moving body 12 is accurately measured. That is, if the first moving body 12 slides to the left (upward in the figure) with respect to the moving direction, the optical path length increases, and if it slides to the right (downward in the figure), the optical path length decreases.

Third, as shown in FIG. 9B, the vertical light wave interferometer 160 disposed in the first space 14 is fixed on the first moving body 12 at an elevation angle of 45 ° with respect to the moving direction. A third optical axis constituted by the mirror 162 that has been moved and the mirror 164 that is arranged on the first moving body 12 in parallel with the moving direction.
It is a length measurement system. By measuring the optical path length including the vertical direction of the first moving body 12 (in the case of FIG. 9A, the front and back sides of the paper surface) by the third length measuring system, the amount of vertical sliding with respect to the moving direction of the first moving body 12 Is measured accurately. That is, the first
If the moving body 12 slides up (see FIG. 9B) with respect to the moving direction, the optical path length increases, and if it slides down (see FIG. 9B), the optical path length decreases.

In the case where the first moving body 12 (or the second moving body 16) is composed of a traveling body engaged with the guide rail and a table connected to the traveling body by an elastic member. Since it is the table that actually slides, various mirrors are provided on this table.

FIG. 10 (a) shows a case in which the first moving body 12 (or the second moving body 16) is composed of the running body 12a and the table 12b as described above to cancel the sliding in the left-right direction. The example of arrangement | positioning of an elastic member and a control means is shown. As shown in FIG.
a and the table 12b are connected by an elastic hinge 166. The elastic hinge 166 is arranged on a straight line passing through the center of gravity of the first moving body 12. This elastic hinge 166
Is such that the elastic limit of BeCu or phosphor bronze is 50, for example.
kg / mm ² or more, and the bending direction (Fig. 10
(In the case of (a), left-right direction)
It can be easily displaced left and right. Also,
The electrostatic actuator 168, which is a control means, is interposed between the protrusion 12c formed on the upper surface of the traveling body 12a and the protrusion 12d formed on the lower surface of the table 12b at substantially the center of gravity of the lower surface of the table 12b. . Therefore, the detected first moving body 12 (specifically, the table 12b)
Electrostatic actuator 1 according to the amount of horizontal sliding of
By expanding and contracting 68, the table 12b can be moved left and right parallel to the traveling body 12a.

Similarly, FIG. 10 (b) shows the table 12
The example of arrangement of the elastic member and the control means for canceling the vertical slide of b is shown. As shown in FIG. 10B, the traveling body 12a and the table 12b are connected by an elastic hinge 170. The elastic hinge 170 is arranged on a straight line passing through the center of gravity of the first moving body 12, for example, B
The elastic limit of eCu or phosphor bronze is, for example, 50 kg / mm ²
It is formed of the above-mentioned material, and has a concave shape in the bending direction (vertical direction in the case of FIG. 10B) so that it can be easily displaced in the vertical direction. The electrostatic actuator 172, which is a control unit, is interposed between the traveling body 12a and the table 12b so as to abut the lower surface of the table 12b substantially at the position of the center of gravity. Therefore, by extending and contracting the electrostatic actuator 172 in accordance with the detected vertical sliding amount of the first moving body (specifically, the table 12b), the table 12b
It can be moved up and down in parallel to a.

By the way, the first moving body 12 (table 1) provided to each of the aforementioned electrostatic actuators 168 and 172 is provided.
2b) is shifted by the traveling direction light wave interferometer 150 (third direction).
The optical path length L1 of the first optical axis obtained from the light wave interferometer 22)
And the optical path length L2 of the second optical axis obtained from the left-right optical interferometer 154 and the third optical axis L3 obtained from the vertical optical interferometer 160. First, the difference Clr of the optical path lengths L1, L2, L3 when the table 12b is at the reference position (the slide amount is zero) = L1−L2,
Cud = L1−L3 is determined in advance. And the table 12
Using the L1A and L2A measured when b is actually moving, the table 12b is set so that L1A-L2A = Clr.
Is generated, a control for eliminating the horizontal sliding of the table 12b can be performed in real time.

Similarly, using L1A and L3A measured when the table 12b is actually moving, L1A−L3A =
By generating a control signal for controlling the table 12b in the vertical direction so as to obtain the Cud, the table 12b is generated in real time.
It is possible to perform control for eliminating vertical sliding of b.

As described above, the amount of sliding in the direction perpendicular to the direction of movement of the traveling body 12a constituting the first moving body 12 is used as the true linear reference of the laser light of the light wave interferometer, thereby enabling the table 12b to be highly accurate. Can be controlled to move the camera straight.

Although FIGS. 10 (a) and 10 (b) show a configuration in which the control in the horizontal direction and the control in the vertical direction are performed separately, the control may be performed simultaneously or continuously by combining the two as necessary. Is performed, more accurate attitude control can be performed.

If the slide control is performed after the above-described yaw angle control, the slide control is performed after the pitch angle control, or the slide control is performed after the pitching control and the yawing control, a more accurate table can be obtained. Attitude control can be performed.

Further, using the position measuring device shown in FIG.
When measuring the position of the second moving body 16 that moves in the atmosphere, the above-described slide control is applied, and the second moving body 16 is moved.
If control is also performed, more accurate measurement can be performed.
FIG. 11 shows an example of the configuration in that case.

In FIG. 11, when the control of the second moving body 16 is performed, the posture for detecting the posture of the second moving body 16 in the atmosphere is added to the posture fluctuation detecting means of the table 12b shown in FIG. Three systems of fluctuation detecting means are required (FIG. 11)
Are not shown for the three systems for the table 12b). The relative posture (slide) of the second moving body 16 in the atmosphere with respect to the first moving body 12 (table 12a) moving in the first space 14 can be detected by the three systems of posture fluctuation detecting means shown in FIG. Becomes

The first of the three systems forms a fourth optical axis passing through the window of the partition wall 20 provided in the chamber forming the first space 14, and the second moving body 16 moving in the atmosphere.
Is a fourth length measuring system for measuring an accurate movement amount in the movement direction of the first moving body 12 and the second moving direction light wave interferometer 176 and the first moving body 12 in the first space 14 inclined by 45 ° with respect to the moving direction. And a mirror 180 provided on the second moving body 16 in the atmosphere at an angle of 45 ° with respect to the moving direction.
And a mirror 182 disposed on the second moving body 16 so as to be orthogonal to the moving direction.
Perform the measurement of 4.

Second, a second left-right optical wave interferometer 184 disposed in the first space 14 and a mirror 186 fixed on the first moving body 12 at 45 ° with respect to the moving direction, This is a fifth length measuring system in which a fifth optical axis is constituted by a mirror 188 arranged on the second moving body 16 in parallel with the moving direction.
By measuring the optical path length L5 of the second moving body 16 in the left-right direction (vertical direction on the paper) by the fifth length measuring system, the sliding amount in the left-right direction with respect to the moving direction of the second moving body 16 is accurately measured.

Third, a second vertical light wave interferometer 190 disposed in the first space 14 and a mirror 192 fixed on the first moving body 12 at 45 ° with respect to the moving direction, A mirror 194 fixed on the second moving body 16 at an angle of elevation of 45 ° with respect to the moving direction and a mirror 196 arranged on the second moving body 16 in parallel with the moving direction constitute a sixth optical axis. 6 measurement system. By measuring the optical path length L6 including the vertical direction of the second moving body 16 (in FIG. 11, the front and back sides of the paper surface) by the sixth length measuring system, the amount of vertical sliding with respect to the moving direction of the second moving body 16 can be accurately determined. To measure.

The measured optical path lengths L4, L5, L6 are the first
Similarly to the case of the moving body 12, the difference between the optical path lengths L4, L5, and L6 when the second moving body 165 is at the reference position (the sliding amount is zero) is obtained as Clr = L4-L5 and Cud = L4-L6. . Then, using L4A and L5A measured when the second moving body 16 is actually moving, L4A-L5A = Cl
By generating a control signal for controlling the second moving body 16 in the left-right direction so as to achieve r, it is possible to perform control for eliminating the left-right sliding of the second moving body 16 in real time.

Similarly, using L4A and L6A measured when the second moving body 16 is actually moving, L4A−L6A =
If a control signal for controlling the second moving body 16 in the vertical direction so as to become Cud is generated, the table 17 is controlled in real time.
4 can be controlled to eliminate vertical sliding.

Since the mirrors 178, 186, and 192 constituting the fourth, fifth, and sixth length measuring systems are fixedly arranged on the first moving body 12, the mirrors 178, 186, and 192 are relatively positioned with respect to the first moving body 12. When the attitude control of the second moving body 16 is performed, the first attitude control is performed with high accuracy by the laser beam that travels straight without being affected by the fluctuation of the air in the substantially vacuum first space 14.
Needless to say, it is possible to control the posture of the second moving body 16 with the accuracy according to the moving body 12. That is,
It is possible to use laser light in a vacuum as an indirect reference substantially, greatly improve the straightness of movement of the moving body (table) in the atmosphere, and perform highly accurate measurement of the moving body. Can be.

[0110]

As described above, according to the present invention,
The displacement (position) of a moving object placed in the air or an environment identified with the same can be measured with high accuracy.

Further, according to the present invention, the displacement of a moving object can be measured with the same accuracy as the light wave interferometer in vacuum.

Further, according to the present invention, it is possible to realize the displacement measurement without much limitation of the measurable range.

Further, according to the present invention, the moving body in the atmosphere can be moved straight by controlling the yaw angle, the pitch angle, or the slide with an accuracy close to the straightness of the laser beam in a vacuum.

[Brief description of the drawings]

FIG. 1 is a principle explanatory view showing a principle of measuring a relative displacement according to the present invention.

FIG. 2 is a conceptual diagram showing a schematic configuration of a position measuring device according to the present invention.

FIG. 3 is a diagram showing a specific configuration example of a position measuring device according to the present invention.

FIG. 4 is a more detailed configuration diagram of the position measuring device shown in FIG.

FIG. 5 is a block diagram showing a configuration of an electric system of the apparatus shown in FIG. 4;

FIG. 6 is a plan view showing yaw angle control of a first moving body.

FIG. 7 is another configuration diagram of the traction control magnetic circuit.

FIG. 8 is an explanatory diagram illustrating left and right sliding with respect to a moving direction.

FIG. 9 is a configuration diagram illustrating an example of a posture change detection unit that detects a slide amount.

FIG. 10 is an explanatory diagram illustrating a connection state between a traveling body and a table when performing slide control.

FIG. 11 is a configuration diagram illustrating an example of a posture change detection unit that detects a slide amount of a second moving body in the atmosphere.

[Explanation of symbols]

10A first light wave interferometer, 10B second light wave interferometer, 1
2 1st moving body, 14 1st space, 16 2nd moving body, 1
8 2nd space, 20 partition, 22 3rd light wave interferometer, 2
4 position and orientation control unit, 26 relative displacement calculation unit, 27 main control unit, 28 transparent member, 30 laminar flow forming unit, 32 attitude control unit, 100 first measurement optical path, 102 second measurement optical path, 200 vertical control unit, 202 Left and right control unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00 G05D 3/00

Claims (20)

(57) [Claims] 1. An apparatus for measuring a relative displacement of a first moving body and a second moving body that run in parallel with each other, wherein first and second moving bodies are provided with a predetermined angular relationship on the first moving body. A first and second terminal reflecting mirrors arranged on the second moving body at right angles to a reflection optical axis exiting from the first and second relay reflecting mirrors; A first length measuring device for transmitting and receiving a light wave to and from the first terminal reflecting mirror via the relay reflecting mirror, and measuring a length of the first measuring optical path; and via the second relay reflecting mirror A second length measuring instrument for transmitting and receiving light waves to and from the second terminal reflecting mirror to measure the length of the second measuring optical path; and a change in output of the first length measuring instrument before and after the movement and the second measuring instrument. An act of calculating a relative displacement between the first moving body and the second moving body based on a change in the output of the length measuring instrument; Relative displacement measuring apparatus comprising: the means. 2. The apparatus according to claim 1, wherein a reference optical axis output from the first length measuring instrument and the second length measuring instrument is set in parallel with a main motion direction of the first moving body and the second moving body. The first relay reflector is provided at an angle of α with respect to the reference optical axis, and the second relay reflector is π / 2- with respect to the reference optical axis.
A relative displacement measuring device provided with an angle of α. 3. The apparatus according to claim 2, wherein said calculating means calculates a difference between an output change of said first length measuring instrument and an output change of said second length measuring instrument before and after exercise. measuring device. 4. The apparatus according to claim 1, wherein the first moving body, the first and second relay reflectors, and the first and second length measuring instruments are housed in a first space, The two moving bodies and the first and second terminal reflecting mirrors are accommodated in a second space, and the first space and the second space are separated by a partition having a light-transmitting portion with optical transparency. A relative displacement measuring device characterized by the above-mentioned. 5. The apparatus according to claim 4, wherein the first space is evacuated, or the first space has a fluctuation fluctuation of a refractive index of light more than a second gas contained in the second space. A relative displacement measuring device characterized by being filled with a first gas having a small amount of gas. 6. The relative displacement measuring device according to claim 5, wherein the second gas is air or a gas having a composition close to air. 7. The relative displacement according to claim 4, wherein a transparent body is inserted in a part or all of a gap between the first and second terminal reflecting mirrors and the partition. measuring device. 8. The apparatus according to claim 4, further comprising a steady flow forming means for forming a steady flow of gas in a part or all of a gap between the first and second terminal reflecting mirrors and the partition. A relative displacement measuring device, characterized in that: 9. The apparatus according to claim 4, wherein the reflection optical axes exiting from the first and second relay reflectors intersect in a gap between the partition and the first and second terminal reflectors. Or a relative displacement measuring device characterized by approaching. 10. The relative displacement measuring device according to claim 1, wherein the first moving body is housed in a vacuum vessel and driven by an external magnetic action. 11. A position measuring device provided with the relative displacement measuring device according to claim 1, wherein the first moving member is made to follow the movement of the second moving member so that the relative displacement becomes zero. A tracking control mechanism that controls the position of the first moving body; and a position measuring unit that measures the position of the second moving body as the position of the first moving body. 12. An apparatus for controlling the postures of a first moving body and a second moving body, wherein the first light wave interferometer measures the posture of the first moving body, and a measurement result of the first light wave interferometer. A first control means for controlling the posture of the first moving body to move in parallel with a predetermined reference axis based on the first moving body; and a first control means provided with a predetermined angular relationship on the first moving body. A moving body reflecting mirror; and a second moving body provided on the second moving body with a predetermined angular relationship with respect to a reflection optical axis emitted from the first reflecting mirror.
A moving body reflecting mirror; a second light wave interferometer for measuring a posture of the second moving body based on light reflected from the first moving body reflecting mirror and the second moving body reflecting mirror; and the second light wave interferometer And a second control unit that controls the posture of the second moving body so as to move in parallel with the first moving body based on the measurement result of (1). 13. The apparatus according to claim 12, wherein the first moving body is housed in a space substantially in a vacuum state.
A posture control device for a moving body according to the above. 14. The attitude control device for a moving body according to claim 12, wherein the first moving body is accommodated in a space charged with a gas having less fluctuation of the refractive index of light than air. . 15. The first moving body and the second moving body,
13. The moving body according to claim 12, wherein the partition walls are separated from each other by a partition, and the partition on an optical path between the first moving body reflecting mirror and the second moving body reflecting mirror is formed of a transparent body. Attitude control device. 16. A magnet is provided on the first moving body, an electromagnet is provided on the second moving body so as to face the magnet, and a magnetic force between the magnet and the electromagnet is provided. 13. The attitude control device for a moving body according to claim 12, wherein the first moving body is driven in a non-contact manner by interaction. 17. A towing magnet is further provided on the first moving body, and a towing electromagnet is further provided on the second moving body so as to face the towing magnet. 13. The posture control device for a moving body according to claim 12, wherein the first moving body is caused to follow the second moving body by a magnetic attraction force between a magnet for use and the towing electromagnet. 18. The apparatus according to claim 18, wherein at least one of said first control means and said second control means controls at least one of a yaw angle and a pitch angle of said first moving body or said second moving body. The posture control device for a moving body according to claim 12. 19. The apparatus according to claim 19, wherein at least one of said first control means and said second control means controls a slide in a direction orthogonal to a direction of movement of said first moving body or said second moving body. A posture control device for a moving body according to claim 12. 20. At least one of the first control means and the second control means includes a length measurement system in a vertical direction with respect to a movement direction of the first moving body or the second moving body, and a horizontal measurement system. 20. The posture control device for a moving body according to claim 19, wherein the control is performed based on the posture detected by the long system.