JP2020085606A - Displacement detector - Google Patents

Abstract

To provide a displacement detector with which it is possible to shorten the time taken for measurement work.SOLUTION: A displacement detector 1 comprises a head 3 arranged facing the surface to be measured of a member to be measured, and a displacement output unit for outputting the displacement of the member to be measured. The head 3 includes a light irradiation part, a displacement detection part, and a received light detection part. The displacement detection part divides into a first beam and a second beam, and emits the first beam, for each of a plurality of beam groups L1-L5, in a track direction Y with a prescribed space therebetween. The received light detection unit outputs a plurality of interference signals. The displacement output unit includes a relative position output part, a measured member position information acquisition part, and a map information output part. The relative position output part calculates relative position information relative to the head 3 in a height direction Z of multiple points P1-P5 on a measured surface Ma on the basis of the interference signals and outputs the calculated information. The relative position output part includes a synchronization part for causing the relative position information in height direction of the multiple points on the measured surface to be synchronized.SELECTED DRAWING: Figure 1

Description

The present invention relates to a displacement detection device that detects a displacement of a surface to be measured by a non-contact sensor that uses light emitted from a light source.

2. Description of the Related Art Conventionally, a displacement detection device using light has been widely used as a device for measuring the displacement and shape of a surface to be measured without contact. As a typical example, there is a method of irradiating a surface to be measured with laser light and detecting a change in the position of reflected light by PSD. However, this method has a problem that it is easily affected by the inclination of the surface to be measured, its sensitivity is low, and the resolution of the measurement decreases when the measurement range is widened.

On the other hand, there is a method of using a Michelson interferometer with the measured surface as a mirror. This method has a wide detection range and excellent linearity, but when the measurement range is widened, the wavelength of the light source changes and the refractive index of air changes.

On the other hand, the light emitted from the light source is condensed on the surface to be measured by the objective lens, the reflected light reflected on the surface to be measured is condensed by the astigmatic optical element and is incident on the light receiving element, and is focused by the astigmatism method. Generate an error signal. Then, the servo mechanism is driven by using the focus error signal, and the objective lens is displaced so that the focal position of the objective lens becomes the surface to be measured. At this time, there is a method of detecting the displacement of the surface to be measured by reading the scale of a linear scale integrally attached to the objective lens via a connecting member (see, for example, Patent Document 1). This method has the merit of being less susceptible to changes in the inclination of the surface to be measured and capable of measuring a large measurement range with high resolution.

In the displacement detection device disclosed in Patent Document 1, in order to improve the accuracy of displacement detection, the numerical aperture (NA: Numerical Aperture) of the objective lens is increased to reduce the beam diameter to be focused on the surface to be measured. ing. For example, when the diameter of the beam focused on the surface to be measured is set to about 2 μm, the detection accuracy of the linear scale becomes about several nm to several hundred nm.

JP-A-5-89480

In recent years, it has been required to check not only the displacement of the measured member in the height direction but also the state of the measured surface of the measured member. However, in the technique described in Patent Document 1, it is possible to detect only one displacement of the surface to be measured in the member to be measured, and in order to confirm the entire state of the surface to be measured, a plurality of measurement operations are required. There is a problem that it is necessary to perform the measurement twice and the measurement work takes time.

An object of the present invention is to provide a displacement detection device that can reduce the time required for measurement work.

In order to solve the above problems and achieve the object of the present invention, the displacement detection device of the present invention is a displacement output that outputs the displacement of a head and a head that is arranged to face the surface to be measured of the member to be measured. And a section. The head and the member to be measured are relatively movable in a scanning direction which is orthogonal to the height direction in which the surface to be measured and the head face each other and is parallel to the surface to be measured.
The head includes a light irradiation unit, a displacement detection unit, and a light reception detection unit.
The light irradiation section irradiates a plurality of light flux groups. The displacement detection unit splits the plurality of light flux groups emitted from the light irradiation unit into a first light flux serving as object light and a second light flux serving as reference light. Further, the displacement detection unit irradiates the plurality of light flux groups with the first light flux at a predetermined interval in the track direction which is parallel to the surface to be measured and orthogonal to the scanning direction. Then, the displacement detection unit generates interference light by superimposing the first light flux and the second light flux reflected by the member to be measured. The light reception detection unit receives the interference light for each of the plurality of light flux groups generated by the displacement detection unit, and outputs a plurality of interference signals.
The displacement output unit includes a relative position output unit, a measured member position information acquisition unit, and a map information output unit. The relative position output unit calculates and outputs the relative position information in the height direction with respect to the head at a plurality of positions on the measured surface based on the plurality of interference signals output from the light reception detection unit. The measured member position information acquisition unit acquires the scanning direction of the measured member with respect to the head, and the coordinate position in the track direction which is parallel to the measured surface and orthogonal to the scanning direction. The map information output unit, relative position information in the height direction of a plurality of locations on the measured surface output from the relative position output unit, the scanning direction and the track direction of the measured member acquired by the measured member position information acquisition unit. Map information indicating the state of the surface to be measured of the member to be measured is output based on the coordinate position. The relative position output unit has a synchronization unit that synchronizes relative position information in the height direction at a plurality of positions on the surface to be measured.

According to the displacement detection device of the present invention, it is possible to reduce the time required for the measurement work.

It is a schematic block diagram which shows the structure of the displacement detection apparatus concerning the 1st Example of this invention. FIG. 3 is a plan view showing an internal configuration of a head of the displacement detection device according to the first exemplary embodiment of the present invention. It is a schematic block diagram which shows the structure of the displacement detection part of the displacement detection apparatus concerning the 1st Embodiment of this invention. FIG. 4A is a sectional view showing an example of the diffraction grating of the displacement detecting apparatus according to the first exemplary embodiment of the present invention, and FIG. 4B is a sectional view showing a second example of the diffraction grating. is there. It is a schematic block diagram which shows the structure of the light reception detection part of the displacement detection apparatus concerning the 1st Embodiment of this invention. It is a block diagram which shows the displacement output part of the displacement detection apparatus concerning the 1st Embodiment of this invention. It is a block diagram which shows the relative position output part of the displacement detection apparatus concerning the 1st Example of this invention. It is explanatory drawing which shows the principal part of the displacement detection apparatus concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the other example of the displacement detection operation in the displacement detection apparatus concerning the 1st Embodiment of this invention. It is a schematic block diagram which shows the light irradiation part of the displacement detection apparatus concerning the 2nd Embodiment of this invention. It is a top view which shows the structure inside the head of the displacement detection apparatus concerning the 3rd Example of this invention.

Hereinafter, an example of an embodiment of the displacement detection device of the present invention will be described with reference to FIGS. In each figure, common members are designated by the same reference numerals. The present invention is not limited to the following modes.
Further, the various lenses described in the following description may be a single lens or a lens group.

1. First Embodiment First, a configuration of a displacement detection device according to a first embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described with reference to FIGS. 1 to 6.

1-1. Configuration Example of Displacement Detection Device FIG. 1 is a schematic configuration diagram showing a configuration of the displacement detection device.

The displacement detection device 1 of this example is a displacement detection device that can detect a displacement in a vertical direction on a measured surface by using a transmission diffraction grating. As shown in FIG. 1, the displacement detection device 1 has a head 3 that faces the surface Ma to be measured of the member M to be measured, and a displacement output unit 4 (see FIG. 6) that outputs displacement. The displacement output unit 4 may be housed in the head 3, or may be arranged in a portable information processing terminal provided outside the head 3 or a PC (personal computer).

At least one of the head 3 and the member to be measured M is configured to be movable in a first direction X that is parallel to the surface to be measured Ma and indicates a scanning direction. In this example, the head 3 is fixed, and the measured member M moves in the first direction X.

Hereinafter, the direction orthogonal to the first direction X and parallel to the surface Ma to be measured, that is, the track direction will be referred to as the second direction Y. Further, a direction orthogonal to the first direction X and the second direction Y, that is, a height direction in which the head 3 and the measured member M face each other is referred to as a third direction Z.

FIG. 2 is a schematic configuration diagram showing an internal configuration of the head 3.
As shown in FIG. 2, the head 3 includes a light source 11, a light flux group splitting unit 12 that splits the light emitted from the light source 11 into a plurality of light flux groups, a displacement detection unit 13, and a light reception detection unit 15. There is.

Examples of the light source 11 include a semiconductor laser diode, a super luminescence diode, a gas laser, a solid-state laser, and a light emitting diode.

When a light source having a long coherence length is used as the light source 11, the tilt allowable range is widened because it is unlikely to be affected by the optical path length difference between the object light and the reference light due to the tilt of the measured surface Ma of the measured member M or the like. Further, as the coherence length of the light source 11 becomes shorter, noise due to interference of unnecessary stray light can be prevented, and highly accurate measurement can be performed.

Furthermore, when a single mode laser is used as the light source 11, it is desirable to control the temperature of the light source 11 in order to stabilize the wavelength. Further, high-frequency superimposition or the like may be added to the light of the single mode laser to reduce the coherence of the light. Further, even when a multimode laser is used, by controlling the temperature of the light source 11 with a Peltier element or the like, noise due to unnecessary stray light interference can be prevented, and more stable measurement can be performed.

Further, an optical fiber may be arranged between the light source 11 and the light flux group division unit 12, and the light L emitted from the light source 11 may be guided to the light flux group division unit 12 using the optical fiber. As a result, the light source 11 serving as a heat source can be arranged away from the displacement detection unit 13 and the light reception detection unit 15 described later, and more stable measurement can be performed.

The light L emitted from the light source 11 enters the light flux group division unit 12. Incidentally. A lens (not shown) such as a collimator lens is arranged between the light source 11 and the light flux group division unit 12. The lens collimates the light emitted from the light source 11 into parallel light. Therefore, the light collimated into parallel light by the lens enters the light flux group division unit 12.

The light flux group splitting unit 12 is composed of, for example, a plurality of beam splitters. The light flux group division unit 12 is arranged along the second direction Y. The light flux group splitting unit 12 emits the light L emitted from the light source 11 and collimated into parallel light by a lens (not shown) at a predetermined interval H1 in the second direction Y to generate a first light flux group L1 and a second light flux group L2. It is divided into a light flux group L2, a third light flux group L3, a fourth light flux group L4, and a fifth light flux group L5.

In this example, the light flux group dividing unit 12 divides the light L into five light flux groups L1, L2, L3, L4, and L5, but the present invention is not limited to this. The number of divisions of the luminous flux group division unit 12 may be 4 or less, or 6 or more. The luminous flux group splitting unit 12 may be capable of splitting into at least two luminous flux groups.

The light flux group splitting unit 12 reflects the split light flux groups L1, L2, L3, L4, and L5 in the first direction X and makes the light flux incident on the displacement detecting unit 13. The light source 11 and the luminous flux group division unit 12 constitute a light irradiation unit of this example.

[Displacement detector]
FIG. 3 is a schematic configuration diagram showing the displacement detector 13.
As shown in FIG. 3, the displacement detecting unit 13 includes a light beam splitting unit 21, a first reflection/transmission unit 22, a transmission type diffraction grating 23, a mirror 24 showing an example of a reference reflection unit, and a second reflection unit. The transmission unit 25, the first phase plate 26, the second phase plate 27, the light beam combining unit 28, and the third phase plate 29 are provided.

As shown in FIG. 2, the light beam splitting unit 21, the first reflection/transmission unit 22, the transmission type diffraction grating 23, the mirror 24, the second reflection/transmission unit 25, the first phase plate 26, the second phase plate 27, The light beam combining portion 28 and the third phase plate 29 are arranged in the head 3 so as to extend in the second direction Y. Further, the light beam splitting unit 21, the first reflection/transmission unit 22, the transmission type diffraction grating 23, the mirror 24, the second reflection/transmission unit 25, the first phase plate 26, the second phase plate 27, the light beam combining unit 28, The third phase plates 29 are arranged side by side in the head 3 along the first direction X.

Further, as shown in FIG. 3, the first reflective/transmissive portion 22 and the second reflective/transmissive portion 25 are arranged to face each other in the first direction X. A diffraction grating 23, a mirror 24, a first phase plate 26, and a second phase plate 27 are arranged between the first reflection/transmission part 22 and the second reflection/transmission part 25. The mirror 24 is arranged at the same position as the diffraction grating 23 in the first direction X, and the reflecting surface 24a of the mirror 24 is parallel to the first direction X and the second direction Y, and In the direction Z, it is arranged at a position facing the measured surface Ma of the measured member M. In addition, the first phase plate 26 and the second phase plate 27 are arranged between the diffraction grating 23 and the second reflection/transmission unit 25 in the first direction X.

As shown in FIGS. 2 and 3, the light beam splitting unit 21 is composed of, for example, a beam splitter or a half mirror. The first light flux group L1, the second light flux group L2, the third light flux group L3, the fourth light flux group L4, and the fifth light flux group L5, which are split by the light flux group splitting unit 12, enter the light flux splitting unit 21. The optical paths of the following luminous flux groups L1, L2, L3, L4, and L5 are the same, so the first luminous flux group L1 will be described.

The light beam splitting unit 21 splits the incident first light beam group L1 into a first light beam LA serving as object light and a second light beam LB serving as reference light. The first light beam LA that passes through the light beam splitting unit 21 travels toward the member M to be measured in the third direction Z, and the second light beam LB reflected by the light beam splitting unit 21 is the third direction Z. In, the object moves toward the side opposite to the member M to be measured. Further, a first reflection/transmission unit 22 and a mirror 24 are arranged on the side of the light beam splitting unit 21 in the first direction X opposite to the light source 11 and the light beam group splitting unit 12.

The first light flux LA and the second light flux LB that have been split by the light flux splitting portion 21 enter the first reflection/transmission portion 22. The first reflection/transmission unit 22 is composed of, for example, a polarization beam splitter. In this example, the first reflection/transmission unit 22 transmits p-polarized light and reflects s-polarized light.

The first reflective/transmissive portion 22 has a reflective/transmissive surface 22a substantially parallel to a diffractive surface of a diffraction grating 23 described later, and is approximately 90° with respect to the measured surface Ma of the measured member M and the reflective surface 24a of the mirror 24. It is arranged so that.

The first reflection/transmission unit 22 transmits the first light beam LA and the second light beam LB divided by the light beam division unit 21. The first light flux LA transmitted through the first reflection/transmission part 22 is incident on the measured surface Ma of the measured member M. The first light flux LA1 of the first light flux group L1 is incident on the first irradiation point P1 on the measured surface Ma. The first light flux LA2 of the second light flux group L2 is incident on the second irradiation point P2 of the measured surface Ma. The first light flux LA3 of the third light flux group L3 is incident on the third irradiation point P3 of the measured surface Ma. The first light flux LA4 of the fourth light flux group L4 is incident on the fourth irradiation point P4 on the measured surface Ma. The first light flux LA5 of the fifth light flux group L5 is incident on the fifth irradiation point P5 on the measured surface Ma. The first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 are simultaneously irradiated.

The first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 have the same coordinates in the first direction X. Then, the first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 are arranged along the second direction Y at a predetermined interval H1. It The intervals of the first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 in the second direction Y, that is, the coordinates of the irradiation point are the displacement outputs described below. It is stored in advance in the section 4.

Further, when the measured member M is arranged at the reference position, the first light flux LA that has passed through the first reflection/transmission unit 22 is at the reference point (which is substantially the same position on the measured surface Ma of the measured member M ( It is incident on a specific position).

Then, the first light flux LA incident on the measured surface Ma is reflected by the measured surface Ma. The first light flux LA reflected by the surface-to-be-measured Ma is incident on the second reflection/transmission unit 25 via the first phase plate 26. The second light flux LB that has entered the mirror 24 is reflected by the mirror 24 and then enters the second reflection/transmission unit 25 via the second phase plate 27.

The first phase plate 26 and the second phase plate 27 change the polarization direction of the light passing therethrough, and are composed of, for example, a half-wave plate or the like. Therefore, when the polarization direction of the passing light is p polarization, it is changed to s polarization, and when the polarization direction of the passing light is p polarization, it is changed to s polarization.

The second reflection/transmission unit 25 is a polarization beam splitter, like the first reflection/transmission unit 22. The second reflection/transmission unit 25 transmits p-polarized light and reflects s-polarized light. The second reflective/transmissive portion 25 has a reflective/transmissive surface 25a substantially parallel to a diffractive surface of a diffraction grating 23 described later, and is substantially parallel to the measured surface Ma of the measured member M and the reflective surface 24a of the mirror 24. It is arranged so as to be 90°.

The first light flux LA reflected by the second reflection/transmission unit 25 is incident on the diffraction grating 23 via the first phase plate 26. Similarly, the second light flux LB reflected by the second reflection/transmission unit 25 is incident on the diffraction grating 23 via the second phase plate 27.

The diffraction grating 23 is a transmissive diffraction grating and transmits and diffracts incident light. The diffraction grating 23 is substantially perpendicular to the measured surface Ma of the measured member M and the reflection surface 24a of the mirror 24, that is, the angle formed by the diffraction surface of the diffraction grating 23 and the measured surface Ma is approximately 90°. Are arranged as follows.

The arrangement accuracy of the diffraction grating 23, the first reflection/transmission part 22, and the second reflection/transmission part 25 with respect to the member to be measured M is set variously according to the measurement accuracy required for the displacement detection device 1. That is, when the displacement detection device 1 is required to have high accuracy, the diffraction grating 23, the first reflection/transmission part 22 and the second reflection/transmission part 25 are set within a range of about 90°±0.5° with respect to the measured surface Ma. It is preferable to arrange them. On the other hand, even if the diffraction grating 23, the first reflection/transmission part 22 and the second reflection/transmission part 25 are arranged in the range of 90° to ±2° with respect to the surface Ma to be measured, the displacement detection device 1 is machined Sufficient when used for low precision measurements on machines and the like.

Since the diffraction grating 23 is arranged at 90° with respect to the measured surface Ma, when the first light flux LA is incident on the measured surface Ma of the measured member M at the incident angle θ1, the first light flux LA is , Incident on the diffraction grating 23 at an incident angle of π/2−θ1.

The first light beam LA and the second light beam LB that have been transmitted through the diffraction grating 23 and are diffracted again enter the first reflection/transmission unit 22. Then, the first light flux LA is reflected by the first reflection/transmission part 22 and is incident on the measured surface Ma of the measured member M again. In addition, when the measured member M is arranged at the reference position, the first light flux LA is incident on the same reference point as the first time. The second light flux LB is reflected by the first reflection/transmission unit 22 and is incident on the mirror 24 again.

The diffraction angle of the diffraction grating 23 may be substantially equal to the angle of incidence on the diffraction grating 23, or may not be equal. It should be noted that the grating pitch Λ of the diffraction grating 23 is preferably set to a value that satisfies the following Expression 1, where θ1 is the first and second incident angles to the measured member M and λ is the wavelength.
[Formula 1]
Λ=nλ/2sin(π/2−θ1)

As the diffraction grating 23, for example, diffraction gratings 23A and 23B as shown in FIGS. 4A and 4B may be used.
FIG. 4A is a sectional view showing an example of the diffraction grating, and FIG. 4B is a sectional view showing another example of the diffraction grating.

The diffraction grating 23A shown in FIG. 4A has a grating portion 23b made of, for example, chromium (Cr) formed on one surface of a substantially transparent glass substrate 23Aa. Generally, since the lattice portion 23b is formed by vacuum-depositing a thin film of chromium or the like on one surface of the glass substrate 23Aa, its thickness is 1 μm or less.

The diffraction grating 23B shown in FIG. 4B is a so-called volume type hologram using a photographic plate. Although an absorption hologram may be used, a phase hologram will be described here. The grating portion 23c of the diffraction grating 23B is formed, for example, as follows. First, a silver salt emulsion sensitive to light is applied to one surface of the glass substrate 23Ba, the interference fringes are exposed, and after development, bleaching is performed. As a result, a portion 23d where silver particles remain and a portion 23e where silver particles do not remain are formed in the lattice portion 23c. Here, the portion 23d where the silver particles remain has a high refractive index, and the portion 23e where the silver particles do not remain has a low refractive index. That is, it is a phase hologram. Further, a photopolymer for hologram recording may be used as a material instead of the photographic plate.

In the case of the diffraction grating 23B having such a configuration, when light is incident at a predetermined angle (incident angle), the light is output (diffracted) at a predetermined angle (diffraction angle). Further, when the Bragg condition is satisfied, the output of the diffracted light diffracted by the diffraction grating 23B can be maximized. That is, it is possible to prevent the light amount of the diffracted light diffracted by the diffraction grating 23B from decreasing.

The thickness N1 of the grating portion 23c of the diffraction grating 23B is preferably four times or more the grating pitch Λ. However, considering that light is absorbed by the grating portion 23c, the thickness N1 of the grating portion 23c is preferably set to about 4 to 20 times the grating pitch Λ.

Further, the diffraction grating 23B formed of a volume type hologram as shown in FIG. 4B enhances the diffraction efficiency of the first light flux LA reflected from the measured member M and the second light flux LB reflected from the mirror 24. Therefore, the noise of the signal can be reduced.

Further, as shown in FIG. 2 and FIG. 3 again, the second reflection/transmission part 25 is transmitted through the side opposite to the side facing the first reflection/transmission part 22 and the diffraction grating 23, that is, the second reflection/transmission part 25. A third phase plate 29 and a light beam combining portion 28 are arranged on the side.

The third phase plate 29 changes the polarization direction of passing light similarly to the first phase plate 26 and the second phase plate 27, and is composed of, for example, a half-wave plate or the like. There is.

The first light flux LA transmitted through the second reflection/transmission portion 25 and the second light flux LB transmitted through the second reflection/transmission portion 25 and passed through the third phase plate 29 are incident on the light flux coupling portion 28. To do. The light beam combining unit 28 is a polarization beam splitter. The light flux combining unit 28 transmits p-polarized light and reflects s-polarized light. Then, the light flux combining unit 28 superimposes the first light flux LA and the second light flux LB to generate interference lights LC1 to LC5 (hereinafter simply referred to as interference light LC). The light flux combining section 28 irradiates the received light detecting section 15 with the superimposed interference light LC.

[Light receiving detector]
Next, the light reception detector 15 will be described.
FIG. 5 is a schematic configuration diagram showing the light reception detection unit 15.

As shown in FIG. 5, the light reception detector 15 includes a fourth phase plate 31, a beam splitter 32 formed of a half mirror, a fifth phase plate 33 formed of a ½ wavelength plate, and a first phase plate 33. It has a polarization beam splitter 34 and a second polarization beam splitter 35. The fourth phase plate 31, the beam splitter 32, the fifth phase plate 33, the first polarization beam splitter 34, and the second polarization beam splitter 35 are arranged in the head 3 similarly to the constituent members of the displacement detector 13. It is arranged so as to extend in the second direction Y.

The fourth phase plate 31 is composed of, for example, a quarter-wave plate, changes the passing interference light LC into circularly polarized light, and the polarization directions of the first light beam LA and the second light beam LB are opposite to each other. The optical axis of the phase plate is set so as to be oriented.

The beam splitter 32 splits the interference light LC transmitted through the fourth phase plate 31 into two. One of the lights split by the beam splitter 32 is incident on the first polarization beam splitter 34, and the other light is incident on the second polarization beam splitter 35 via the fifth phase plate 33. To do.

The fifth phase plate 33 is arranged such that the polarization direction of the interference light entering the second polarization beam splitter 35 is inclined by 45 degrees with respect to the first polarization beam splitter 34. The first polarization beam splitter 34 and the second polarization beam splitter 35 split the light by reflecting the light having the s-polarized component and transmitting the light having the p-polarized component.

The first light receiving portion 15A, the second light receiving portion 15B, the third light receiving portion 15C, the fourth light receiving portion 15D, and the fifth light receiving portion 15A are provided on the light exit side of the first polarization beam splitter 34 and the second polarization beam splitter 35. The light receiving portion 15E (see FIG. 7) is arranged.

The first light receiving unit 15A, the second light receiving unit 15B, the third light receiving unit 15C, the fourth light receiving unit 15D, and the fifth light receiving unit 15E are arranged along the second direction Y at a predetermined interval H1. The first light receiving portion 15A receives the first interference light LC1 of the first light flux group L1, the second light receiving portion 15B receives the second interference light LC2 of the second light flux group L2, and the third light receiving portion 15C. , And receives the third interference light LC3 of the third light flux group L3. Then, the fourth light receiving unit 15D receives the fourth interference light LC4 of the fourth light flux group L4, and the fifth light receiving unit 15E receives the fifth interference light LC5 of the fifth light flux group L5.

The first light receiving portion 15A has a first light receiving element 41A, a second light receiving element 42A, a third light receiving element 43A, and a fourth light receiving element 44A. The first light receiving element 41A and the second light receiving element 42A are disposed on the exit side of the first polarization beam splitter 34, and the third light receiving element 43A and the fourth light receiving element 44A are the second polarization beam splitter 35. Is arranged on the emission port side of.

The second light receiving portion 15B, the third light receiving portion 15C, the fourth light receiving portion 15D, and the fifth light receiving portion 15E have four light receiving elements similarly to the first light receiving portion 15A. The first light receiving elements 41B to 41E and the second light receiving elements 42B to 42E are arranged on the exit side of the first polarization beam splitter 34. The third light receiving elements 43B to 43E and the fourth light receiving elements 44B to 44E are arranged on the exit side of the second polarization beam splitter 35.

The first light receiving unit 15A, the second light receiving unit 15B, the third light receiving unit 15C, the fourth light receiving unit 15D, and the fifth light receiving unit 15E receive the signals received by the respective light receiving elements 41A to 43E, and photoelectrically convert the signals into the displacement output unit 4. Output to.

As described above, the fifth phase plate 33 is arranged so that the polarization direction of the interference light entering the second polarization beam splitter 35 is inclined by 45 degrees with respect to the first polarization beam splitter 34. Therefore, when the phase of the interference signal of the first light receiving elements 41A to 41E is sin, the phase of the interference signal of the second light receiving elements 42A to 42E is -sin. Then, the phases of the interference signals of the third light receiving elements 43A to 43E are cos, and the phases of the interference signals of the fourth light receiving elements 44A to 44E are -cos.

[Displacement output section]
Next, the configuration of the displacement output unit 4 will be described with reference to FIGS. 6 and 7.
FIG. 6 is a block diagram showing the displacement output unit 4.

As shown in FIG. 6, the displacement output unit 4 includes a relative position output unit 101, a measured member position information acquisition unit 102, a map information output unit 103, a map information storage unit 104, and a map comparison information output unit 105. And have.

The relative position output unit 101 receives signals photoelectrically converted by the first light receiving unit 15A, the second light receiving unit 15B, the third light receiving unit 15C, the fourth light receiving unit 15D, and the fifth light receiving unit 15E. The relative position output unit 101 calculates and outputs displacement information of relative change in the third direction Z with respect to the head 3 on the measured surface Ma of the measured member M based on the received signal. The detailed configuration of the relative position output unit 101 will be described later. Then, the relative position output unit 101 outputs the calculated displacement information in the third direction Z to the map information output unit 103.

The member-to-be-measured position information acquisition unit 102 acquires position information of the member M to be measured in the first direction X and the second direction Y with respect to the head 3 from an encoder provided separately from the head 3, for example. Then, the measured member position information acquisition unit 102 outputs the acquired position information of the measured member M in the first direction X and the second direction Y to the map information output unit 103 and the map information storage unit 104.

In this example, the example in which the position information in the first direction X and the second direction Y is acquired from the encoder provided separately from the head 3 has been described, but the present invention is not limited to this. For example, the head 3 is provided with a displacement detection unit that measures position information of the measured member M in the first direction X and the second direction Y, and from the displacement detection unit, the first direction X and the first direction X of the measured member M are measured. The position information in the direction Y of 2 may be acquired.

The map information output unit 103 stores the position coordinates of the irradiation points P1, P2, P3, P4, and P5 in the displacement detection unit 13 in advance. The map information output unit 103 outputs the displacement information in the third direction Z on the measured surface Ma output from the relative position output unit 101 and the first measured member M acquired by the measured member position information acquisition unit 102. Based on the position information in the direction X and the second direction Y, the state of the measured surface Ma, that is, map information is calculated and output.

A map information storage unit 104 and a map comparison information output unit 105 are connected to the map information output unit 103. The map information output unit 103 outputs the calculated map information of the measured surface Ma to the map information storage unit 104 and the map comparison information output unit 105.

The map information storage unit 104 stores the position information of the measured member M in the first direction X and the second direction Y output from the measured member position information acquisition unit 102, and the position information output from the map information output unit 103. The map information of the measuring member M is stored. A map comparison information output unit 105 is connected to the map information storage unit 104. Then, the map information storage unit 104 outputs the stored map information to the map comparison information output unit 105. The map comparison information output unit 105 compares the first map information stored in the map information storage unit 104 with the second map information output from the map information output unit 103.

Next, a detailed configuration of the relative position output unit 101 will be described with reference to FIG. 7.
FIG. 7 is a block diagram showing the relative position output unit 101.

As shown in FIG. 7, the relative position output unit 101 includes a first relative position output unit 101A, a second relative position output unit 101B, a third relative position output unit 101C, and a fourth relative position output unit 101D. It has a fifth relative position output unit 101E and a clock synchronization unit 69 showing an example of a synchronization unit.

The first relative position output unit 101A receives the interference signal from the first light receiving unit 15A, the second relative position output unit 101B receives the interference signal from the second light receiving unit 15B, and the third relative position output unit 101C , And receives the interference signal from the third light receiving unit 15C. Further, the fourth relative position output unit 101D receives the interference signal from the fourth light receiving unit 15D, and the fifth relative position output unit 101E receives the interference signal from the fifth light receiving unit 15E.

The first relative position output unit 101A calculates relative position information in the third direction Z of the first irradiation point P1 at which the first light flux LA1 of the first light flux group L1 is incident on the measured surface Ma. The second relative position output unit 101B calculates relative position information in the third direction Z of the second irradiation point P2 at which the first light flux LA2 of the second light flux group L2 is incident on the measured surface Ma. The third relative position output unit 101C calculates relative position information in the third direction Z of the third irradiation point P3 at which the first light flux LA3 of the third light flux group L3 is incident on the measured surface Ma. The fourth relative position output unit 101D calculates relative position information in the third direction Z of the fourth irradiation point P4 at which the first light flux LA4 of the fourth light flux group L4 is incident on the measured surface Ma. Then, the fifth relative position output unit 101E calculates relative position information in the third direction Z of the fifth irradiation point P5 at which the first light flux LA5 of the fifth light flux group L5 is incident on the measured surface Ma.

The first relative position output unit 101A, the second relative position output unit 101B, the third relative position output unit 101C, the fourth relative position output unit 101D, and the fifth relative position output unit 101E have the same configuration. Therefore, the first relative position output unit 101A will be described here.

The first relative position output unit 101A includes two differential amplifiers 61a and 61b, two A/D converters 62a and 62b, a waveform correction processing unit 63, and an incremental signal generator 64.

A first light receiving element 41A and a second light receiving element 42A are connected to the first differential amplifier 61a, and a third light receiving element 43A and a fourth light receiving element 44A are connected to the second differential amplifier 61b. There is. Further, the first differential amplifier 61a is connected to the first A/D converter 62a, and the second differential amplifier 61b is connected to the second A/D converter 62b. The first A/D converter 62a and the second A/D converter 62b are connected to the waveform correction processing unit 63. Further, the waveform correction processing unit 63 is connected to the incremental signal generator 64.

The first differential amplifier 61a receives the interference signal from the first light receiving element 41A and the second light receiving element 42A, and the second differential amplifier 61b receives the interference signal from the third light receiving element 43A and the fourth light receiving element 44A. To do. The first differential amplifier 61a and the second differential amplifier 61b differentially amplify the received interference signals and cancel the DC component of the interference signals.

The signal differentially amplified by the first differential amplifier 61a is A/D converted by the first A/D converter 62a, and the waveform correction processing unit 63 corrects the signal amplitude, offset, and phase. This signal is calculated in the incremental signal generator 64 as an A-phase incremental signal, for example.

The signal differentially amplified by the second differential amplifier 61b is A/D converted by the second A/D converter 62b, and the waveform correction processing unit 63 corrects the signal amplitude, offset, and phase. When the phase of the interference signal obtained by the first light receiving element 41A and the second light receiving element 42A is a sin signal, the phase of the interference signal obtained by the third light receiving element 43A and the fourth light receiving element is a cos signal. .. Therefore, the signal corrected by the waveform correction processing unit 63 is calculated in the incremental signal generator 64 as a B-phase incremental signal whose phase is different from the A-phase by 90 degrees.

The two-phase incremental signals thus obtained are discriminated by a pulse discrimination cairo (not shown). Accordingly, it is possible to detect whether the relative displacement amount of the head 3 and the member to be measured M in the third direction Z is the plus direction or the minus direction.

Further, by counting the number of pulses of the incremental signal by a counter (not shown), it is possible to measure how many cycles of the above-mentioned cycle the interference light intensity of the first light beam LA and the second light beam LB has changed. Thereby, the relative displacement amount of the head 3 and the member to be measured M in the third direction Z can be detected.

Further, the relative position information output by the relative position output unit 101 of this example may be the above-described two-phase incremental signal or a signal including the displacement amount and the displacement direction calculated therefrom.

The incremental signal generator 64 calculates the phase change per clock to generate the displacement of the measured member M in the third direction Z as a digital signal.

The first A/D converter of the first relative position output unit 101A, the second relative position output unit 101B, the third relative position output unit 101C, the fourth relative position output unit 101D, and the fifth relative position output unit 101E. 62a and the second A/D converter 62b are connected to the clock synchronization unit 69.

The clock synchronization unit 69 synchronizes the time of the signals output by the first A/D converter 62a and the second A/D converter 62b in the first relative position output unit 101A to the fifth relative position output unit 101E. I am letting you. Thereby, the first relative position output unit 101A, the second relative position output unit 101B, the third relative position output unit 101C, the fourth relative position output unit 101D, and the third direction detected by the fifth relative position output unit 101E. It is possible to synchronize the detection time of the Z displacement amount. As a result, it is possible to simultaneously detect the displacement amounts in the third direction Z at a plurality of locations (first irradiation point P1 to fifth irradiation point P5) on the measured surface Ma.

As described above, by synchronizing the A/D converters 62a and 62b in which the frequency of the output signal is high among the elements configuring the relative position output units 101A to 101E, more accurate map information can be acquired. ..

In this example, the example in which the A/D converters 62a and 62b of the relative position output units 101A to 101E are synchronized by the clock synchronization unit 69 has been described, but the present invention is not limited to this. For example, the elements different from the A/D converters 62a and 62b may be used for synchronization, or all elements constituting the relative position output units 101A to 101E, that is, two differential amplifiers 61a and 61b and two A's. A synchronization unit may be connected to the /D converters 62a and 62b, the waveform correction processing unit 63, and the incremental signal generator 64 for synchronization.

1-2. Operation of Displacement Detection Device Next, the operation of the displacement detection device 1 of this example will be described with reference to FIGS. 1 to 3 and 8.
FIG. 8 is an explanatory diagram showing a main part of the displacement detection device.

As shown in FIGS. 2 and 3, the light L emitted from the light source is collimated by a lens (not shown) to be parallel light. Then, the collimated light collimated by the lens enters the light flux group division unit 12. The light that has entered the light flux group splitting unit 12 is spaced apart in the second direction Y by a predetermined distance H1, and the first light flux group L1, the second light flux group L2, the third light flux group L3, the fourth light flux group L4, and the fourth light flux group L4. It is divided into five light flux groups L5. Then, the first light flux group L1, the second light flux group L2, the third light flux group L3, the fourth light flux group L4, and the fifth light flux group L5 are incident on the displacement detection unit 13.

The optical paths from the displacement detecting unit 13 to the light receiving detecting unit 15 in the first light flux group L1, the second light flux group L2, the third light flux group L3, the fourth light flux group L4, and the fifth light flux group L5 are substantially the same. Therefore, the first light flux group L1 will be described here.

The first light flux group L1 that has entered the displacement detection unit 13 is split by the light flux splitting unit 21 into a first light flux LA serving as object light and a second light flux LB serving as reference light. The first light flux LA and the second light flux LB pass through the first reflection/transmission unit 22. Then, the first light flux LA is incident on the measured surface Ma of the measured member M, and the second light flux LB is incident on the mirror 24.

As described above, the first light flux LA1 of the first light flux group L1 enters the first irradiation point P1 of the measured surface Ma. The first light flux LA2 of the second light flux group L2 is incident on the second irradiation point P2 of the measured surface Ma. The first light flux LA3 of the third light flux group L3 is incident on the third irradiation point P3 of the measured surface Ma. The first light flux LA4 of the fourth light flux group L4 is incident on the fourth irradiation point P4 on the measured surface Ma. The first light flux LA5 of the fifth light flux group L5 is incident on the fifth irradiation point P5 on the measured surface Ma.

The first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 have the same coordinates in the first direction X. Then, the first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 are arranged along the second direction Y at a predetermined interval H1. It The intervals of the first irradiation point P1, the second irradiation point P2, the third irradiation point P3, the fourth irradiation point P4, and the fifth irradiation point P5 in the second direction Y, that is, the coordinates of the irradiation point are the displacement outputs described below. It is stored in advance in the section 4.

Here, as shown in FIG. 8, when the measured member M is at the reference position, the first light flux LA is incident on the reference point P0 of the measured member M at the incident angle θ ₁ . Then, the first light flux LA is reflected by the member to be measured M for the first time and is incident on the second reflection/transmission unit 25 via the first phase plate 26 (see FIG. 3 ). The first light flux LA changes its polarization direction from p-polarized light to s-polarized light by passing through the first phase plate 26. Therefore, the first light flux LA is reflected by the reflection/transmission surface 25a of the second reflection/transmission unit 25, and is incident on an arbitrary diffraction position T0 of the diffraction grating 23 at an incident angle π/2−θ ₁ .

The first light flux LA is diffracted by the diffraction grating 23 and enters the first reflection/transmission unit 22. As described above, since the polarization direction of the first light flux LA is changed to the s-polarized light, the first light flux LA is reflected by the reflection/transmission surface 22a of the first reflection/transmission part 22 and is again reflected on the measurement surface Ma of the measurement target member M. Incident.

Here, the reflection/transmission surface 22a of the first reflection/transmission part 22 is arranged so that the first light flux LA diffracted by the diffraction grating 23 can be incident on the same reference point P as at the first time and at the same incident angle θ _1. ing. Therefore, when the member to be measured M is at the reference position, the first light flux LA is incident on the reference point P0 of the member to be measured M, which is substantially the same position as the first time, at the incident angle θ ₁ .

After that, the first light flux LA follows the same optical path as the first optical path, is reflected by the member M to be measured, and passes through the first phase plate 26 (see FIG. 3) to the second reflection/transmission unit 25. Incident. The first light beam LA changes its polarization direction from s-polarized light to p-polarized light by passing through the first phase plate 26. Therefore, the first light beam LA passes through the second reflection/transmission unit 25 and enters the light beam combining unit 28.

The optical path of the first light flux LA that is incident on the reference point P0 of the measured member M and is shown by the solid line in FIG. 8 is referred to as reference light.

As described above, when the measured member M is at the reference position, in this example, the first irradiation position and the second irradiation position of the first luminous flux LA on the measured member M are set at substantially the same position of the reference point P0. It can be irradiated. As a result, the detection point interval Q on the measured member M can be minimized.

Further, as shown in FIG. 3, the second light flux LB that is the object light is reflected by the mirror 24 and is incident on the second reflection/transmission unit 25 via the second phase plate 27. The second light beam LB changes its polarization direction from p-polarized light to s-polarized light by passing through the second phase plate. Therefore, the second light flux LB is reflected by the second reflection/transmission unit 25 and enters the diffraction grating 23. Then, the second light flux LB is diffracted by the diffraction grating 23 and enters the first reflection/transmission unit 22.

Since the second light flux LB is s-polarized light, it is reflected by the first reflection/transmission unit 22 and enters the mirror 24 again. Then, the second light flux LB is reflected by the mirror 24 and enters the second reflection/transmission unit 25 via the second phase plate 27. The second light beam LB changes its polarization direction from s-polarized light to p-polarized light by passing through the second phase plate. Therefore, the second light flux LB is transmitted by the second reflection/transmission unit 25.

The second light flux LB transmitted through the second reflection/transmission portion 25 is incident on the light flux coupling portion 28 via the third phase plate 29.

Here, the optical path length from the light beam splitting portion 21 to the light flux combining portion 28 in the first light flux LA and the optical path length from the light flux splitting portion 21 to the light flux combining portion 28 in the second light flux LB are set to be equal to each other. , A mirror 24 is arranged. This makes it possible to easily adjust the optical path length of the first light flux LA and the optical path length of the second light flux LB or the angle of the optical axis when manufacturing the displacement detection device 1. As a result, stable measurement can be performed regardless of the surrounding environment without performing atmospheric pressure correction, humidity correction, and temperature correction.

Further, the first light flux LA and the second light flux LB are made incident on the same diffraction grating 23 and diffracted. As a result, even if the diffraction angle of the diffraction grating 23 changes due to the temperature change, it is possible to equalize the effects on the first light flux LA and the second light flux LB.

Here, as shown in FIG. 8, a case where the measured member M moves from the reference position in the height direction which is the third direction Z by z/2 will be described.
As shown in FIG. 8, when the member to be measured M moves from the reference position in the height direction by z/2, the irradiation position of the first light flux LA for the first time is from the reference point P0 of the member to be measured M to the first position. To the irradiation position Pb1. Note that the incident angle theta ₁ to the object body M is the same as the incident angle theta ₁ of the first light beam LA is irradiated to the reference point P0. Then, the first light flux LA follows the optical path indicated by the dotted line and enters the diffraction grating 23 at an incident angle π/2−θ ₁ . Since the incident angles on the member M to be measured are equal, the incident angle π/2-θ ₁ on the diffraction grating 23 in the first light beam LA when moved is the diffraction of the first light beam LA that follows the reference optical path. The angle of incidence on the grating 23 is the same as π/2−θ ₁ .

Further, the incident position of the first light flux LA on the diffraction grating 23 moves from the diffraction position T0 to the diffraction position T1. Here, since the diffraction grating 23 is arranged substantially at right angles to the measured surface Ma of the measured member M, the distance between the diffraction position T0 and the diffraction position T1 is twice the moving distance of the measured member M. Z of. Then, the phase of only the wave number of z components moved on the diffraction grating 23 is added to the first light beam LA.

Then, the first light flux LA is reflected by the first reflective/transmissive portion 22 and again enters the measured member M. The irradiation position of the second light flux LA for the second time moves from the first irradiation position Pb1 of the measured member M to the second irradiation position Pb2. Note that the incident angle theta ₁ to the object body M, the first incidence angle theta ₁ and the light flux LA irradiated to the reference point P0, the same as the incident angle theta ₁ of the first of the first light beam LA ..

The optical path indicated by the alternate long and short dash line of the second light flux LA irradiated on the measured member M coincides with the reference optical path by the solid line. Further, the optical path length of the first light beam LA is Is always constant even when is displaced in the height direction. That is, the wavelength of the first light flux LA does not change. Therefore, the first light beam LA is added with the phase of only the wave number of z that has moved on the diffraction grating 23 from the diffraction position T0 to the diffraction position T1.

Further, the displacement detection device 1 detects the center position Pa between the first irradiation position Pb1 and the second irradiation position Pb2 as the detection position. As shown in FIG. 8, the center point Pa substantially coincides with the reference point P0. Therefore, even if the member M to be measured moves in the height direction, it is possible to always detect the displacement at substantially the same detection position. As a result, it becomes possible to measure a surface to be measured with a narrow detection point interval Q.

Returning to FIG. 3, the first light beam LA that has entered the light beam combining unit 28 is p-polarized light and therefore passes through the light beam combining unit 28. The second light flux LB changes its polarization direction from s-polarized light to p-polarized light by passing through the third phase plate 29. Therefore, the second light flux LB that has entered the light flux combining unit 28 is reflected by the light flux combining unit 28. As a result, the first light flux LA and the second light flux LB are superposed by the light flux combining unit 28 to become interference light LC. Then, the interference light LC is incident on the fourth phase plate 31 of the light reception detector 15.

Here, since the first light flux LA is p-polarized light and the second light flux LB is s-polarized light, the interference light LC passes through the fourth phase plate 31 to thereby generate the first light flux LA and the second light flux LA. The light flux LB is a circularly polarized light whose rotation directions are opposite to each other. Further, the phase of the wave number corresponding to the movement on the diffraction grating 23 is added to the first light flux LA. Therefore, it is possible to obtain the interference light having the linearly polarized light that rotates with the phase addition of the wave number of the first light flux LA that has moved on the diffraction grating 23. This rotation of the linearly polarized light makes one rotation when the measured member M moves in the height direction by the grating pitch Λ of the diffraction grating 23.

The interference light LC is split into two by the beam splitter 32. One of the split lights is incident on the first polarization beam splitter 34, and the other light is incident on the second polarization beam splitter 35 via the fifth phase plate 33. Then, the first polarization beam splitter 34 and the second polarization beam splitter 35 reflect the interference light having the s-polarized component and transmit the interference light having the p-polarized component to split the light.

The interference light transmitted through the first polarization beam splitter 34 is received by the first light receiving element 41A. The interference light reflected by the first polarization beam splitter 34 is received by the second light receiving element 42A. Here, the signals photoelectrically converted by the first light receiving element 41A and the second light receiving element 42A are signals having a phase difference of 180 degrees.

Similarly, the interference light transmitted through the second polarization beam splitter 35 is received by the third light receiving element 43A. The interference light that has passed through the second polarization beam splitter 35 is received by the fourth light receiving element 44A. Here, the signals photoelectrically converted by the third light receiving element 43A and the fourth light receiving element 44A are signals having a phase difference of 180 degrees.

The first light receiving element 41A and the second light receiving element 42A, and the third light receiving element 43A and the fourth light receiving element 44A obtain an interference signal of Acos (2Kx+δ). A is the amplitude of interference, and K is the wave number represented by 2π/Λ. Further, x represents a displacement amount in the height direction which is the third direction Z in the measured member M, and δ represents an initial phase. Λ is the pitch of the diffraction grating 23.

As described above, when the measured member M moves by z/2 in the height direction, the first light flux LA irradiated on the measurement surface of the measured member M moves from the reference point P0 to the first irradiation position Pb1. Moving. Further, the first light flux LA reflected by the measured member M moves from the diffraction position T0 of the diffraction grating 23 to the diffraction position T1. The distance between the diffraction position T0 and the diffraction position T1 is z, which is twice the distance between the reference point P0 and the first irradiation position Pb1. That is, the amount of movement of the first light beam LA moving on the diffraction grating 23 becomes z, which is twice as large as when the member M to be measured is moved.

Further, since the diffraction grating 23 is arranged substantially at right angles to the surface to be measured of the member to be measured M, even if the member to be measured M is displaced in the height direction, the optical path length of the first light flux LA is always It becomes constant, and the wavelength of the first light flux LA does not change. When the measured member M is displaced in the third direction Z (height direction), only the position of incidence on the diffraction grating 23 changes.

That is, when the measured member M moves in the height direction by z, a phase of 2 Kz is added to the diffracted first light beam LA. Therefore, the interference light in which the light and shade of the light of two cycles occur is received by the first light receiving element 41A, the second light receiving element 42A, the third light receiving element 43A, and the fourth light receiving element 44A.

Here, the interference signal obtained by the first light receiving element 41A, the second light receiving element 42A, the third light receiving element 43A, and the fourth light receiving element 44A does not include a component related to the wavelength of the light source 11. Therefore, even if the wavelength of the light source 11 changes due to changes in atmospheric pressure, humidity, and temperature, the interference intensity is not affected.

Further, the signals obtained by the third light receiving element 43A and the fourth light receiving element 44A are 90 degrees out of phase with the signals obtained by the first light receiving element 41A and the second light receiving element 42A. Therefore, the Lissajous signal is obtained by setting the signal obtained by the first light receiving element 41A and the second light receiving element 42A as the sin signal and the signal obtained by the third light receiving element 43A and the fourth light receiving element 44A as the cos signal. be able to.

The signals obtained by these light receiving elements are calculated by the relative position output section 101 of the displacement output section 4, and the first irradiation point P1, the second irradiation point P2, the third irradiation point P3, and the fourth irradiation point on the surface Ma to be measured are calculated. The displacement amount of the point P4 and the fifth irradiation point P5 can be detected. The clock synchronization unit 69 causes the first relative position output unit 101A, the second relative position output unit 101B, the third relative position output unit 101C, the fourth relative position output unit 101D, and the fifth relative position output unit 101E to clock Since the synchronization is achieved by the synchronization unit 69, it is possible to detect the displacement amounts of a plurality of points on the measured surface Ma at the same time.

Note that the displacement information output by the relative position output unit 101 does not include absolute position information. However, the incremental signal includes absolute information with a cycle of cos (2Kx). For example, when the pitch of the diffraction grating 23 is 1.6 μm, the incremental signal includes absolute information with a period of 0.8 μm. For example, in the case of a high-precision semiconductor manufacturing apparatus, when measuring the height of the member M to be measured on the stage, it is easy to move the stage with a repeatability of 0.8 μm.

The relative position output unit 101 outputs the calculated displacement information in the third direction Z at each irradiation point P1, P2, P3, P4, P5 to the map information output unit 103. Further, to the map information output unit 103, the position information of the member to be measured M in the first direction X and the second direction Y is output from the member to be measured position information acquiring unit 102. As a result, the map information output unit 103 calculates the coordinate positions of the irradiation points P1, P2, P3, P4, P5 in the first direction X and the second direction Y on the measured surface Ma. Then, the map information output unit 103 outputs displacement information in the third direction Z at each irradiation point P1, P2, P3, P4, P5 output from the relative position output unit 101, and each irradiation point P1, P2, P3, The coordinate positions of the first direction X and the second direction Y in P4 and P5 are associated with each other. Accordingly, the map information output unit 103 can output displacement information of each point on the measured surface Ma in the third direction Z.

Further, as shown in FIG. 1, when the head 3 or the member M to be measured is moved in the first direction X, the map information output unit 103 causes the irradiation points P1, P2, P3, P4, and P5 to move in the first direction. The displacement information in the direction Z of 3 and the position information in the first direction X and the second direction Y in the measured member M are acquired at the same time. Thereby, the state (map information) of the entire measured surface Ma of the measured member M can be detected at high speed. As a result, the displacement of the measured member M in the height direction (third direction Z) can be detected with high resolution and stability, and the time required for the measurement work can be shortened.

Further, the map information storage unit 104 stores the map information calculated by the map information output unit 103. Then, the map comparison information output unit 105 indicates the first map information stored in the map information storage unit 104, which has been measured before, and the current state of the measured surface Ma output from the map information output unit 103. 2 Compare with map information. The second map information is newer than the first map information. As a result, as shown in FIG. 1, it is possible to compare the displacement amount in the third direction Z between the reference measured member MA serving as the reference and the other measured member M, that is, the difference in shape.

FIG. 9 is an explanatory diagram showing another example of the displacement detection operation in the displacement detection device 1 of this example.
Further, as shown in FIG. 9, by moving the head 3 or the member to be measured M back and forth along the first direction X, it is possible to observe the change with time of the member to be measured M with respect to the initial value. This makes it possible to acquire map information before and after processing the measured member M.

2. Second Exemplary Embodiment Next, a displacement detection device according to a second exemplary embodiment will be described with reference to FIG.
FIG. 10 is a schematic configuration diagram showing a light irradiation unit of the displacement detection device according to the second embodiment.

The displacement detection device according to the second embodiment differs from the displacement detection device 1 according to the first embodiment in the configuration of the light irradiation unit. Therefore, here, only the light irradiator will be described, and the same parts as those of the displacement detection device 1 according to the first embodiment will be designated by the same reference numerals and redundant description will be omitted.

As shown in FIG. 10, the light irradiation unit of the displacement detection device according to the second embodiment includes a light source 11, a collimator lens 18, an isolator 19, and a light beam group division unit (not shown). .. The collimator lens 18 and the isolator 19 are arranged between the light source 11 and the luminous flux group division unit.

The collimator lens 18 collimates the light L emitted from the light source 11 into parallel light and irradiates the isolator 19 with the collimated light. By collimating the light L into parallel light, a sufficient beam diameter can be secured. As a result, even if there are small irregularities or foreign matter on the surface Ma to be measured, it is possible to average them and reduce the disturbance of the interference signal.

The isolator 19 is an optical element that allows the light L to pass in only one direction and blocks the light in the opposite direction. When the light L emitted from the light source 11 is linearly polarized light, the isolator 19 changes the direction of the linearly polarized light.

As a result, the isolator 19 can prevent the 0th-order light emitted to the displacement detection unit 13 and reflected by the displacement detection unit 13 from returning to the light source 11. As a result, it is possible to reduce the occurrence of mode hopping due to unnecessary light from the light source 11, that is, so-called wavelength jump.

Other configurations are the same as those of the displacement detection device 1 according to the first embodiment, and therefore their description is omitted. With the displacement detecting device having such a light irradiating section, it is possible to obtain the same effects as those of the displacement detecting device 1 according to the above-described first embodiment.

3. Third Exemplary Embodiment Next, a displacement detection device according to a third exemplary embodiment will be described with reference to FIG.
FIG. 11 is a schematic configuration diagram showing an internal configuration of the head of the displacement detection device according to the third embodiment.

The displacement detection device according to the third embodiment differs from the displacement detection device 1 according to the first embodiment in the configuration of the light irradiation unit. Therefore, here, only the light irradiator will be described, and the same parts as those of the displacement detection device 1 according to the first embodiment will be designated by the same reference numerals and redundant description will be omitted.

As shown in FIG. 11, the displacement detecting device according to the third exemplary embodiment includes a plurality of light sources 11A, 11B, 11C, 11D, and 11E, a displacement detecting unit 13A, a light receiving detecting unit 15, and an unillustrated one. And a displacement output section. The plurality (five) of light sources 11A, 11B, 11C, 11D, and 11E are arranged side by side along the second direction Y. The first light source 11A irradiates the first light flux group L1, the second light source 11B irradiates the second light flux group L2, and the third light source 11C irradiates the third light flux group L3. Then, the fourth light flux group L4 is emitted from the fourth light source 11D, and the fifth light flux group L5 is emitted from the fifth light source 11E.

Then, the first light flux group L1 is split by the light flux splitting unit 21 of the displacement detection unit 13A into a first light flux LA1 that is the object light and a second light flux LB1 that is the reference light. Then, the first light beam LA1 and the second light beam LB1 are superposed by the light beam combining section 28 to become the interference light LC1. The interference light LC1 enters the light reception detection unit 15.

Further, the optical paths from the displacement detection unit 13A to the light reception detection unit 15 in the second light flux group L2, the third light flux group L3, the fourth light flux group L4, and the fifth light flux group L5 are the same as those of the first light flux group L1. , The description is omitted.

Other configurations are the same as those of the displacement detection device 1 according to the first embodiment, and therefore their description is omitted. As described above, also with the displacement detection device having the plurality of light sources 11A to 11E, it is possible to obtain the same effects as those of the displacement detection device 1 according to the above-described first embodiment.

According to the displacement detecting device of the third embodiment, not only the luminous flux group splitting unit can be omitted, but also the light amount detected by the light reception detecting unit 15 can be increased. Further, also in the displacement detection device according to the third exemplary embodiment, as in the displacement detection device according to the second exemplary embodiment, between the light sources 11A to 11E and the displacement detection unit 13A, the collimator lens 18 and The isolator 19 may be arranged.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention described in the claims. In the above-described embodiment, the light emitted from the light source may be supplied not only in the gas but also in the space in the liquid or in the vacuum to supply the light.

Further, the mirror 24 may be moved in association with the movement of the member M to be measured. That is, the mirror 24 is moved by the same movement amount as the movement amount of the measured member M in the height direction. This makes it possible to add a positive and negative phase to the second light beam LB that is different from that of the first light beam LA.

DESCRIPTION OF SYMBOLS 1... Displacement detection device, 3... Head, 4... Displacement output part, 11... Light source, 12... Luminous flux group division part, 13... Displacement detection part, 15... Light receiving detection part, 15A... 1st light receiving part, 15B... 2nd Light receiving part, 15C... Third light receiving part, 15D... Fourth light receiving part, 15E... Fifth light receiving part, 18... Collimating lens, 19... Isolator, 21... Light beam splitting part, 22... First reflection/transmission part, 22a, 25a ... Reflective/transmissive surface, 23... Diffraction grating, 24... Mirror (reflecting portion for reference), 24a... Reflective surface, 25... Second reflective/transmissive portion, 28... Luminous flux coupling section, 41A... Light receiving element, 42A... Second light receiving element 43A... 3rd light receiving element, 44A... 4th light receiving element, 61a... 1st differential amplifier, 61b... 2nd differential amplifier, 62a... 1st A/D converter, 62b... 2nd A/D Converter, 63... Waveform correction processing unit, 64... Incremental signal generator, 69... Clock synchronization unit (synchronization unit), 101... Relative position output unit, 101A... First relative position output unit, 101B... Second relative position output Part, 101C... Third relative position output unit, 101D... Fourth relative position output unit, 101E... Fifth relative position output unit, 102... Measured member position information acquisition unit, 103... Map information output unit, 104... Map information Storage unit 105... Map comparison information output unit, H1... Interval, L1... First light flux group, L2... Second light flux group, L3... Third light flux group, L4... Fourth light flux group, L5... Fifth light flux group, LA... 1st light flux, LB... 2nd light flux, LC... Interference light, P0... Reference point, P1... 1st irradiation point, P2... 2nd irradiation point, P3... 3rd irradiation point, P4... 4th irradiation Point, P5... Fifth irradiation point, Pb1... First irradiation position, Pb2... Second irradiation position, T0, T1... Diffraction position, X... First direction (scanning direction), Y... Second direction ( Track direction), Z... third direction (height direction)

Claims (9)

A head arranged to face the surface to be measured of the member to be measured,
A displacement output unit that outputs the displacement of the member to be measured,
The head and the member to be measured are relatively movable in a scanning direction which is orthogonal to a height direction which is a direction in which the surface to be measured and the head are opposed to each other, and which is parallel to the surface to be measured.
The head is
A light irradiation unit that irradiates a plurality of light flux groups,
The plurality of light flux groups emitted from the light irradiation unit are divided into a first light flux serving as object light and a second light flux serving as reference light, and the first light flux is grouped into the plurality of light flux groups, The first light flux and the second light flux reflected by the member to be measured are overlapped with each other by irradiating the surface to be measured parallel to the track direction orthogonal to the scanning direction at a predetermined interval. A displacement detector that generates interference light;
A light-reception detection unit that receives the interference light for each of the plurality of light flux groups generated by the displacement detection unit and outputs a plurality of interference signals,
The displacement output unit,
Based on the plurality of interference signals output from the light reception detection unit, relative position information in the height direction with respect to the head at a plurality of positions on the measured surface is calculated, and a relative position output unit that outputs,
The scanning direction of the measured member with respect to the head, and the measured member position information acquisition unit that is parallel to the measured surface, and acquires the coordinate position of the track direction orthogonal to the scanning direction,
Relative position information in the height direction at a plurality of positions on the measured surface output from the relative position output unit, and the scanning direction and the track direction of the measured member acquired by the measured member position information acquisition unit. A map information output unit that outputs map information indicating a state of the measured surface of the measured member based on the coordinate position of
The relative position output unit includes a synchronization unit that includes a synchronization unit that synchronizes relative position information in the height direction at a plurality of positions on the measured surface. The light reception detection unit has a plurality of light reception units that separately receive the interference lights of the plurality of light flux groups,
The relative position output unit has a plurality of relative position output unit that separately obtains the interference signal from the plurality of light receiving units,
Each of the plurality of relative position output units has an A/D converter for A/D converting the interference signal,
The displacement detection device according to claim 1, wherein the synchronization unit is connected to the A/D converters of the plurality of relative position output units and synchronizes a time of a signal output by the A/D converter. The displacement output unit,
A map information storage unit for storing the map information output by the map information output unit;
A map comparison information output unit for comparing the first map information stored in the map information storage unit and the second map information newer than the first map information output by the map information output unit. The displacement detection device according to claim 1. The displacement detector is
A luminous flux splitting unit that splits the luminous flux group into the first luminous flux and the second luminous flux;
A first reflection/transmission unit that transmits or reflects the first light flux and the second light flux according to the polarization directions of the first light flux and the second light flux;
A phase plate that changes the polarization directions of the first light flux and the second light flux;
A reference reflecting section that is arranged so as to face the surface to be measured and that reflects the second luminous flux split by the luminous flux splitting section;
A transmissive diffraction grating that diffracts the first light flux reflected from the surface to be measured, and causes the diffracted first light flux to enter the first reflection-transmission unit again.
A second reflection that is arranged so as to face the first reflection/transmission part and that transmits or reflects the first light flux and the second light flux according to the polarization directions of the first light flux and the second light flux. A transparent part,
A first light flux that has passed through the second reflection/transmission section and a second light flux that are superposed on each other to generate the interference light, and that the light reception detection unit is irradiated with the interference light.
The first reflective/transmissive portion is
Transmitting the first light flux split by the light flux splitting section toward the member to be measured,
The first light flux reflected by the member to be measured and diffracted by the diffraction grating is reflected toward the member to be measured,
The second reflective/transmissive portion,
The first light flux transmitted through the first reflection/transmission part and reflected by the member to be measured is reflected toward the diffraction grating,
The displacement detecting device according to claim 1, wherein the second light flux diffracted by the diffraction grating and reflected again by the member to be measured is transmitted toward the light flux combining portion. The first reflection/transmission part guides the first light flux to a specific position of the member to be measured when the member to be measured is at a reference position,
The displacement according to claim 4, wherein an optical path of the first light flux when reflected again on the surface to be measured overlaps with an optical path when the first light flux is reflected at the specific position on the member to be measured. Detection device. An optical path length from the light beam splitting portion in the first light flux to the light flux coupling portion via the diffraction grating, and a light flux coupling portion from the light flux splitting portion in the second light flux via the reference reflection portion. The optical path lengths up to are set to be substantially equal to each other. The displacement detection device according to any one of claims 4 to 6, wherein the diffraction surface of the diffraction grating is arranged substantially at right angles to the measured surface of the measured member. The light irradiation unit,
A light source that emits light,
The displacement detection according to any one of claims 1 to 7, further comprising: a light flux group splitting unit that splits the light emitted from the light source into the plurality of light flux groups at predetermined intervals in the track direction. apparatus. The light irradiation unit,
The displacement detection device according to claim 1, further comprising a plurality of light sources that emit light corresponding to the plurality of light flux groups.

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