JPH0648170B2 - Displacement measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a displacement measuring device capable of downsizing the device, reducing noise, and improving accuracy by integrating a main part of the device into an IC.

[Prior Art] A conventional grating interference measuring device is three-dimensionally configured by separately combining a light source, a polarizing mirror, a corner cube, a polarizing plate, a photodetector and the like.

[Problems to be Solved by the Invention] Therefore, in the conventional grating interferometric length measuring apparatus, an error is added to the interference signal due to mechanical fluctuation between each optical member, temperature change, air fluctuation, etc. Deteriorate.

Also, because the light source and the detection system are installed separately,
It occupies a large volume in space and cannot be miniaturized.

Furthermore, there is a problem in that noise is likely to enter due to the spatial distance from the detection system to the processing circuit, which deteriorates measurement accuracy.

In view of the problems in the above-described conventional example, the object of the present invention is to
It is an object of the present invention to provide a displacement measuring device that realizes downsizing, low noise, and high accuracy of the device without impairing measurement stability.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a light source for generating a light flux, a surface thereof is arranged so as to face a diffraction grating as a reference scale, and the diffraction grating is arranged in a substantially arrangement direction. A base for movably disposed relative to the diffraction grating, and a waveguide layer provided on a surface of the base facing the diffraction grating and guiding a light beam along the facing surface. A means for dividing the light flux from the light source into two light fluxes provided in the waveguide layer, and deflecting each of the divided light fluxes in a direction intersecting with the facing surface, and thereby a specific portion of the space from the waveguide layer. And an optical integrated circuit provided with means for emitting the light toward the optical waveguide, and a photodetecting means for receiving the mutually interfering light emitted from the waveguide layer and diffracted by the diffraction grating. And

In addition to this, in the present invention, a light source for generating a light flux,
A base whose surface is arranged so as to face the object to be displaced and is arranged so as to be movable relative to the object, and a light beam which is provided on the surface of the base facing the object A waveguide layer guided along the facing surface, a means provided in the waveguide layer for splitting a light beam from the light source into two light beams, and each split light beam is deflected in a direction intersecting with the facing surface. The integrated optical circuit provided with means for emitting light from the waveguide layer to a specific location in space, and the light emitted from the waveguide layer and acted by the object, which interfere with each other, are received. And a light detecting means.

[Operation and Effect] According to the present invention, since the main part is integrated on the facing surface, the displacement measuring device can be configured to be strong against external disturbance, small in size, light in weight, and highly accurate. In addition, before the light enters the object to be inspected, the light beam is divided into two in the optical integrated circuit and is deflected in a direction intersecting with the facing surface and emitted, and the mutually interfering lights from the object to be inspected are received. Therefore, even if the relative positional relationship between the object to be inspected and the optical integrated circuit changes, the state of the light flux passing through the optical integrated circuit is not affected at all, and more stable measurement is possible. In particular, the present invention uses the optical integrated circuit provided in the waveguide layer on the surface facing the object to be inspected, so that the entire device including the object existence space can be made thin, Enables miniaturization.

[Examples] Examples of the present invention will be described below.

FIG. 1 shows an overview of a length measuring device related to the present invention. This processing apparatus processes or measures an object to be processed or an object to be measured using an optical probe.

In the figure, DS is a stage base, the Y stage YS is on the base DS, and the X stage X is on the Y stage YS.
S is mounted. The base DS has a y-direction guide YG,
An X-direction guide XG is provided on the Y stage YS,
The X and Y stages XS and YS are driven by X and Y motors (not shown), and move in the x and y directions along the guides XG and YG.

LI is a laser interference length measuring device as a large stroke length measuring device for measuring the movement amount and position of each of the X and Y stages XS and YS, and CPx and CPy are the laser beams Lx and Ly incident from the length measuring device LI 180 It is a corner cube prism for reversing the angle and returning it to the length measuring instrument LI through an optical path parallel to the original. A portion DV indicated by a dotted line on the X stage XY is an arrangement space for the small stroke stage, the high resolution length measuring device, the optical probe and the like. Length measuring instrument LI and stage base DS
Are fixed on a surface plate (not shown).

FIG. 2 shows a partially enlarged view of the optical probe equal arrangement space DV of FIG. In the figure, DFS is a base for a small stroke stage, a y-direction guide YFG for the small stroke stage is provided, and is fixed on the X stage XS. On this base DFS, a small stroke Y stage YFS is movably mounted along a guide YFG.
A small stroke X stage XFS is movably mounted on the stage YFS along a small stroke stage x-direction guide XFG provided on the Y stage YFS, and an optical probe L for processing or measurement is mounted on the X stage XFS.
P is fixed.

The position of the optical probe LP is the y-coordinate detection length measuring device MY including a y-direction reference scale SY attached to the base DFS and a y-direction length measuring head HY attached to the Y stage YFS.
And x-direction scale SX attached to Y stage YFS
And X-direction measuring head HX attached to X-stage XFS
The x-coordinate detection length measuring instrument MX and
It is detected as a relative position coordinate with respect to S (that is, X stage XS). On the other hand, small stroke stage base DF
The coordinates of S with respect to the surface plate are measured as the positions of the X and Y stages by the laser interference length measuring instrument LI.

That is, in FIG. 2, the large stroke stage X
The movements of S and YS are measured by the laser interferometer length measuring instrument LI, and the movements of the stages XFS and YFS in the small stroke object area are measured by the length measuring devices MX and MY. In this way, the length measuring means is combined with respect to the movement of a certain specific area, and the length measurement for the small stroke movement is provided separately from the length measurement equipment (laser interference length measuring equipment) for the stage movement of the large stroke. High-precision (high-resolution) length measurement was performed by using the length measuring device, and large-stroke and high-precision length measurement was realized by not relying on the error of the length measuring device for moving a large stroke. .

Here, the length measuring device for the small stroke movement does not need to have a small stroke, but is more accurate (higher resolution) than the length measuring device for the large stroke movement at least in the specific area.
It is necessary to be.

FIG. 3 shows an example in which another high-precision and high-resolution length measuring device related to the present invention is set on a one-axis stage. This length measuring device
By combining the grating interferometer and the focus detection means used in the autofocus device, and interpolating between the pulse signals at fixed intervals determined by the optical arrangement of the grating interferometer with the focus measurement output of the focus detection means. , While maintaining the high precision of the grating interferometer, the resolution is improved to achieve higher precision and higher resolution. This length measuring device is concretely represented by the entire configuration of the above-mentioned example, and at the same time, the length measuring device for a small stroke movement (the length measuring device MX of FIG. 2 is a part of the above-mentioned example. , MY) can be preferably used.

In FIG. 3, SR is a moving stage, GS is a diffraction grating as a standard scale, MH is a length measuring head for measuring the moving amount of the moving stage SR with respect to the diffraction grating GS, RG is a guide, SS is a feed screw, MT. Is a motor. The guides RG, RG and the diffraction grating GS are fixed on the surface plate SP in parallel with the moving direction of the moving stage SR indicated by an arrow A, and the moving stage SR is guided along the guide RG by the action of the feed screw SS rotationally driven by the motor MT. Move in the direction of arrow A.

FIG. 4 is an explanatory diagram of the structure of the length measuring head MH.

In the figure, SP is a surface plate, on which a moving stage SR is movably mounted, and a diffraction grating GS is fixed in parallel to the moving direction A of the moving stage SR. Further, a flat mirror PM having a mirror surface perpendicular to the moving direction A is fixed to the moving stage SR, and a fine movement stage (AF stage) AFS is mounted. The fine movement stage AFS is connected to the moving stage SR via a fine driving mechanism PD such as a piezo driving mechanism, and the fine driving mechanism PD moves the moving stage SR relative to the moving stage SR (the direction of arrow A). ), It is possible to move a minute amount in the direction of arrow B, which is the same direction as that of FIG. Further, a length measurement optical system including a grating interference length measurement system and an autofocus (hereinafter referred to as AF) length measurement system is installed on the fine movement stage AFS.

This length measurement optical system includes a light source LD such as a semiconductor laser, a collimator lens CL, beam splitters HM1 and HM2, phase difference plates PF1 and FP2, prism mirrors or corner cube prisms CC1 and CC2, a polarization beam splitter BS, and a photodetector PD1. , PD2, objective lens LN, optical position detector (position sensor) PS, and the like. The light source LD and collimator lens CL are connected to the grating interferometry system and A
It is intended to omit optical components such as shared with the F measuring system.

In FIG. 4, the light beam emitted from the light source LD and collimated by the collimator lens CL is a beam splitter H.
It is divided into two light beams by M1, one of which is the objective lens L
N through the beam splitter HM2 and the other through the diffraction grating G
It is incident on S.

The light incident on the diffraction grating GS is diffracted by the diffraction grating GS, the phase δ of the diffraction grating GS is added to the diffracted wave front, and the phase light of the diffracted wave is exp {i
(Ωt + mδ)}. Where m is the diffraction order,
For example, + 1st-order light and -1st-order light are exp {i (ωt +
δ)} and exp {i (ωt−δ)}. The light ray L11 which is the + 1st-order light and the light ray L12 which is the -1st-order light respectively enter the corner cube prisms CC1 and CC2 via the phase difference plates FP1 and FP2, and are reflected here in the direction opposite to the incident direction and the parallel direction. To be done. The reflected light rays L11 and L12 pass through the phase difference plates FP1 and FP2 twice to be turned into right-handed and left-handed circularly polarized light, and are reflected by the point P of the diffraction grating GS.
1, the moving direction of the moving stage SR (direction of arrow A)
The light beam is diffracted again at a point P2 distant from the beam, and then enters the polarization beam splitter BS via the beam splitter HM2. Light rays L11, L12 having right-handed and left-handed circularly polarized light incident on the polarization beam splitter BS.
Transmits and reflects the polarization beam splitter BS.
The transmitted light LR1 and LR2 and the reflected light LS1 and LS2 become linearly polarized light, respectively, and interfere with each other to cause photodetectors PD1 and PD1.
It is incident on D2.

Since the photodetectors PD1 and PD2 detect the orthogonal components of the two circularly polarized light as the interference light intensity, the photodetectors PD1 and PD2 of the photodetectors PD1 and PD2 when the measuring head MH (AF stage AFS) moves with respect to the diffraction grating GS. The outputs R and S have a phase difference of 90 ° as shown in FIGS. 5 (a) and 5 (b). Based on these two signals R and S at constant levels (c) and (d)
As shown in, each digitized by a circuit not shown,
To measure the relative movement amount of the length measuring head MH and the diffraction grating GS by generating four pulses per cycle as shown in (e) at the rising and falling timings and counting the number of pulses. You can In this case, the period of change in the intensity of the interference light with respect to the movement of the diffraction grating GS by one pitch is 4 periods, and the number of pulses is 16. In addition, during the pulse counting, the direction of the relative movement is detected, and whether to add or subtract the count value is determined according to the detection result. The moving direction can be determined by the levels of the signals (c) and (d) at the generation timing of each pulse in FIG. 5 (e). For example, the level of the signal (d) at the falling timing of the signal (c) is "H" during the forward movement, and is "L" during the backward movement.

Further, the signals R and S shown in FIGS. 5A and 5B are added and subtracted to create signals R + S and R-S having a phase difference of 45 ° with respect to the signals R and S. Also, by binarizing the same as above and generating pulses at the rising and falling timings, it is possible to generate 32 pulses for one pitch movement of the diffraction grating GS. However, in this case, in order to reliably process these signals, it is necessary to consider the fluctuations in the light amount and the diffraction efficiency.

FIG. 6 is an explanatory view of the principle of the grating interferometer.

In the figure, the coherent light incident on the diffraction grating GS is diffracted as ± first-order light. The phase of this diffracted light is the grating G
When S moves, it changes depending on the moving direction. As shown in the figure, when the diffraction grating GS moves one pitch in the x direction, the phase of the + 1st order diffracted light L11 advances by one wavelength, and the −1st order diffracted light L
12 is one wavelength behind. When the diffracted lights L11 and L12 are returned by the corner cubes CP1 and CP2 and diffracted again by the grating GS, the + 1st order diffracted light L11 is further advanced by one wavelength and the −1st order diffracted light L12 is delayed by one wavelength. for that reason,
The interference light that finally combines L11 and L12 is the diffraction grating G
When S moves 1 pitch, the brightness changes 4 times. Therefore, if one pitch of the diffraction grating is 1.6 μm, 1 / 1.6 of 1.6 μm
4, the brightness changes every 0.4 μm. By photoelectrically converting this change in light and dark and counting the light and dark, it is possible to obtain pulses at intervals of 0.4 μm. In the interferometric measuring system shown in FIG. 4 described above, in order to further improve the resolution, the electrical processing is performed for each pitch of the diffraction grating.
Pulses are generated every 16 or 32, that is, every 0.1 μm or 0.05 μm.

Next, a method for detecting the direction of the grating interferometer will be described.

In order to detect the length measurement direction, it is necessary to extract two signals with 90 ° phase shift.

As shown in FIG. 6, circularly polarized light can be obtained by making linearly polarized coherent light λ / 4 plates QW1 and QW2 incident at 45 ° with respect to the fast axis thereof and transmitting them.

When the + 1st-order diffracted light and the -1st-order diffracted light are combined into, for example, left-handed and right-handed circularly polarized lights and combined, the combined light becomes linearly polarized light.

The polarization direction of the linearly polarized light is determined by the phase difference φ of ± first-order light.

Now, counterclockwise circularly polarized light by the + 1st order light is y ₊ = a exp {i (ωt-φ / 2)} x ₊ = a exp {i (ωt-π / 2-φ / 2)} -1st order light When the left-handed circularly polarized light is expressed by y ₋ = a exp {i (ωt + φ / 2)} x ₋ = a exp {i (ωt−π / 2 + φ / 2)}, the plane wave when these are combined is y = y ₊ + y ₋ = a {exp (iφ / 2) + exp (−iφ / 2) x = x ₊ + x ₋ = a {exp (iφ / 2) + exp (−iφ / 2), which is the seventh As shown in the figure, the polarization direction θ is φ / 2
It can be seen that the linearly polarized light is.

Here, a represents the amplitude of the light wave, and ω represents the angular frequency of the light wave.

Therefore, by moving the grating GS by x in FIG. 6, the phase difference φ of the ± first-order light can be obtained by setting the pitch of the grating GS as p. Is obtained. Therefore, the polarization azimuth θ of the combined ± 1st order light is Becomes

The combined linearly polarized light is split by the beam splitter HM3 as shown in FIG. 6, and enters detectors PD1 and PD2 after passing through polarizing plates PP1 and PP2. Two polarizing plates PP
If the transmission axes of 1 and PP2 are different from each other by 45 °, for example, the detector PD1 after passing through the first polarizer PP1 is θ =
When the peak of the light amount is detected when it is 0, the detector PD2 after passing through the second polarizer PP2 That is, The light intensity reaches its peak at. This is a signal having a 90 ° phase difference with respect to the signal of the detector PD1 by the first polarizer. As a result, the measurement direction can be determined.

Next, a method of generating a pulse signal with higher repeatability will be described.

The accuracy (resolution) in the length measuring device of FIG. 3 is, for example, 0.01 μm to 0.002 μm, as will be described later. In order to maximize the high accuracy of the AF length measuring system, it is necessary to generate a pulse signal with high repeat accuracy in the interferometric length measuring system. This repeatability is the accuracy that is resolved by AF
Repeatability of 0.002 μm or less is required.

In the method of increasing the number of pulses per pitch of the grating by the electrical processing as described above, the factors that deteriorate the accuracy are the fluctuation of the light quantity and the fluctuation of the diffraction efficiency. For example,
The signal R, as shown in FIGS. 5 (a) and (b),
If S has a DC level fluctuation or an amplitude fluctuation, the slicing positions V _SR and V _SS will change, and the repeatability will deteriorate.

Therefore, here, it is proposed to use 0 ° and 180 ° signals.

If the difference between the signals of 0 ° and 180 ° is detected, the fluctuation of the DC level and the fluctuation of the amplitude can be removed because they are common to the two signals of 0 ° and 180 °. This is shown in FIG.

When the signal is used at 0 ° and 180 °, the pulse signal appears every 1/2 wavelength. In this case, a pulse signal is output every 0.2 μm, but it may be used as it is.

FIG. 9 shows an example of a configuration for implementing this method. That is, the polarization plates PP1 and P having azimuth angles of 0 ° and 45 °
In addition to P2, a 90 ° polarizing plate PP3 may be provided in another optical path. In the figure, HM3 and HM4 are half mirrors and P
D1, PD2, PD3 are detectors (photodetectors).

Returning to FIG. 4, the light emitted from the light source LD, collimated by the collimator lens CL, and transmitted through the beam splitter HM1 is input to the objective lens LN of the AF length measurement system.

FIG. 10 is an operation explanatory diagram of the AF length measurement system.

In the figure, the light from the light source LD is incident on the objective lens LN at a position decentered from the main optical axis. And
Target of objective lens LN (moving stage S in FIG. 4)
When the mirror surface of the plane mirror PM fixed to R is at the in-focus position (a), the light from the light source LD passes through the optical path indicated by the solid line in FIG. 10 to reach the in-focus position (a) with respect to the objective lens LN. An image of the light spot projected on the mirror surface is formed on the central portion (a) on the sensor PS arranged at the conjugate (image forming) position. When the target PM is at the defocus (non-focus) positions (b) and (c) of the objective lens LN, the sensor PS passes through the optical paths of the two-dot chain line and the broken line of FIG. 10, respectively.
Defocus images are formed at positions (b) and (c) apart from the upper center (a).

FIG. 11 shows a spot state and a light amount distribution on the surface of the sensor PS corresponding to the positions of the respective plane mirrors PM. The difference between the sensor signal amount of the A zone and the sensor signal amount of the B zone on the sensor PS surface has a so-called S-curve characteristic.
Figure 12 shows the relationship defocus amount of the activation signal [Delta] I (= I A _{-I B)} of the sensor signal quantity I _A and I _B obtained by the differential amplifier (not shown) (the target position).
The AF length measurement system of FIG. 4 uses a region in which the relationship between the defocus amount and the differential signal ΔI in this S-shaped characteristic curve is linear.

Next, the operation of the length measuring device of FIGS. 3 and 4 will be described with reference to the flowchart of FIG. 13 and the output waveform diagrams of FIGS. 14 and 15.

The length measuring device in FIG. 3 is configured so that its entire operation is controlled by a central processing unit (not shown).

First, at the start of operation such as power-on, the moving stage S
Initialize by moving R to the origin and resetting the counter when the moving stage SR reaches the origin,
Then, it waits for the input of the moving stage drive command.

When a stage drive command is input in the standby state,
First, the AF operation is performed. That is, based on the output of the AF length measurement system, the piezo minute drive mechanism (piezoelectric actuator) FD
Then, the AF stage AFS is driven to focus the objective lens LN on the plane mirror PM. When the focus is reached, the AF
The stage AFS is locked to the moving stage SR at that position, and the moving stage SR is driven by the motor MT.

In this length measuring device, when the moving stage SR moves, as described above, an electric circuit (not shown) of the grating interferometer length measuring system.
To the period p of the diffraction grating GS fixed to the surface plate SP
A pulse signal comes out every 1/16 of this (see FIGS. 5 and 14). The counter integrates the number of pulses.

When a stop command is input during the movement of the moving stage SR, the central processing unit stops the moving stage SR and calculates the pulse integration number by the counter. Thereafter, the lock of the AF stage AFS is released, the piezoelectric actuator FD is driven to move the AF stage AFS on which the AF system and the grating interference optical system are mounted, and the pulse signals of the grating interference measuring system obtained above The position of the moving stage where the moving stage is located is detected. That is, as shown in FIG. 14, the moving stage S
Assuming that the position where R is stationary is S point and the pulse count number at that time is N, the position of the S point position between the count number N and the next N + 1 is accurately determined by the autofocus means. .

First, the pulse integrated number N of the counter when the moving stage SR is stopped is stored, and the piezoelectric actuator FD moves the AF stage AFS, that is, the length measurement optical system MH by a minute amount (a little more than the pulse interval Δx). Then, defocus is added to the AF length measurement system that targets the plane mirror PM fixedly attached to the moving stage SR, and as shown in FIG. 15, the differential output signal ΔI (the difference signal of the AF sensor PS I _a -I _B) is changed. At this time, if the feed amount of the piezo drive amount is set in the area where the relationship between the defocus amount and the difference signal is linear, the difference signal is determined because the relationship between the difference signal and the defocus amount is known in advance. If given, the defocus amount can be uniquely determined. Therefore, if a small amount is moved to the position corresponding to the Nth pulse by piezo drive, a difference signal at the position corresponding to the Nth pulse is obtained. An amount obtained by adding δ to Δx is the length measurement position of the point S at which the moving stage SR stops. Here, Δx is the period of the pulse train of the grating interferometry system. The fine movement stage AFS on which the optical system is mounted is stationary at the position where the AF signal is 0 (focus position) until the moving stage SR is stationary.

In this length measuring device, for example, if the diffraction grating GS has a grating pitch of 1.6 μm, the period of the pulse signal of the grating interference measuring system is 0.1 μm. Therefore, the piezo drive amount
The above method can be performed by shaking about 0.2 μm, the length can be achieved with the accuracy of AF while maintaining the high stroke of the grating interference measuring device, and the positioning of the stage or the like can be achieved with high accuracy.

For example, the accuracy of AF measurement is
Using 100 (NA≈0.9), C as AF sensor PS
0.01 μm to 0.002 if a CD or position sensor is used
An accuracy of about μm is realized. In this case, the linear area of the AF signal is about 1 μm.

In the length measuring device of FIG. 3, the AF optical system does not necessarily have the image formation (conjugation) relationship between the plane mirror PM position and the AF sensor PS position, and the fine stage AFS
With respect to the amount of movement, a system in which the differential signal of the AF sensor and the light spot position signal (defocus amount with respect to the moving direction) are linear or have characteristics close to linear may be used. If it is not linear, it is advisable to obtain the minute movement amount by storing the relationship between the movement (defocus) amount and the signal in a read only memory (ROM) and reading the movement amount according to the signal.

As described above, the length measuring device shown in FIG. 3 is a combination of a high stroke length measuring device and an optical system having an output whose signal output is almost linear with respect to the movement amount. ), The precision of the high stroke length measuring device is further improved.

As a result, when the signal determined by the optical arrangement such as the order and polarization state of the diffracted light in the case of the conventional grating interferometer is further electrically decomposed to increase the resolution, the fluctuation of the light quantity and the fluctuation of the diffraction efficiency are caused. The problem that an error is likely to occur is solved.

The following points can be modified with respect to the length measuring device shown in FIG.

For example, in the above description, when detecting the defocus amount δ, the AF stage AFS is finely driven to the position corresponding to the Nth pulse and the N + 1th pulse, and the difference signal at both positions is detected to detect the defocus amount. By calculating δ, an accurate defocus amount δ can be obtained even when the pulse interval or the AF sensor output changes.

Further, the high-stroke length measuring means is not limited to the grating interferometric length measuring device, but may be another method such as a laser interferometric length measuring device.

The optical system mounted on the fine movement stage may be only the objective lens of the AF system and the system of the grating interferometer.
It is not necessary that the entire F system be on the fine movement stage.

Further, although FIG. 3 shows the movement of one axis, a composite structure may be similarly used for measuring the length of two or more axes.

Although the AF system shown in FIG. 4 is the TTL-AF system,
An AF system used for an optical pickup of a DAD (Digital Audio Desk) or a video desk, or an AF system used for autofocus of a camera may be used.

Further, as described above, the AF system does not have to be in a so-called imaging relationship, as long as the sensor signal output is almost linear with respect to the moving direction. As long as the light spot moves linearly on the sensor surface, the point on the plane mirror surface shown in FIG. 4 and the sensor surface are not necessarily conjugate.

FIG. 16 is an example in which the length measuring devices related to the present invention are put together as a length measuring unit.

This length measuring unit includes a light source L on the movable stage ST.
D, collimator lens CL, polarization beam splitter HM
1, a λ / 4 plate QW, condenser lenses GL1 and GL2, AF means PS composed of an optical position detection sensor such as a CCD, and the movement of the stage moving part ST is changed.
It is detected as a pulse train signal by the linear grating GS fixed on the stage and the read head MH arranged on the stage fixing part SS.

The stage moving part ST is actively moved by the actuator AT. The measurement reference plane OS of the object MO to be measured is a mirror surface with high surface accuracy.

The main point of this method is that the focus detection circuit FF in the detection processing circuit ED updates and stores the AF output value at that time each time it receives a pulse signal from the pulse train length measuring instrument electric system PC.

FIG. 17 shows the operation flow. Further, FIG. 18 shows an example of the pulse interval and the AF voltage value.

When it is confirmed that the object MO to be inspected has stopped, the actuator AT of the length measurement unit is driven to try to focus the autofocus on the reference surface OS to be inspected. This movement is detected by the scale GS attached to the stage movable part ST and the reading head MH to detect a change in the light amount of the interference light, and the pulse train length measuring device electric system PC counts the change in the light amount as a pulse signal to measure the length. The resolution in this case is the pulse interval Δx
(Fig. 18).

During that time, each time the central processing system CPU receives the pulse signal, the focusing voltage V _AF at that time is updated and stored. When the autofocus system shows a focus signal, that is, V _AF = OV, the actuator AT stops.

Therefore, the CPU of the central processing system calculates the length measurement distance x as x = j · Δx + Vj · ζ using the count number j that has been counted so far and the focusing voltage Vj stored last by the focusing detection system FF. Here, Δx is a moving distance corresponding to the pulse interval and is, for example, 0.4 μm pitch. Further, ζ is assumed to be calibrated in advance with the sensitivity of AF.

FIG. 19 shows an example of using this length measuring unit for two axes,
This is used for highly accurate positioning of an AA (automatic alignment) head of a semiconductor exposure apparatus.

FIG. 20 shows an example in which a laser interferometric length measuring system is used in place of the diffraction grating interferometric length measuring system of the length measuring device shown in FIG. In FIG. 20, the same or corresponding parts as in FIG. 3 are designated by the same reference numerals. In FIG. 20, the laser head LZ, the interference unit IU and the corner cube prism CP constitute a laser interference measuring system. The interference unit IU is fixed to the surface plate SP, and the corner cube prism CP is fixed to the fine movement stage AFS.

FIG. 21 shows an optical measurement system on the fine movement stage AFS of FIG. The beam splitter HM2 and the phase difference plate FP, which are arranged to configure the diffraction grating interference measuring optical system in FIG.
1, FP2, corner cube prism CC1, CC
2, polarization beam splitter BS and photodetector PD1,
The corner cube prism C for removing the PD2 and instead reflecting the laser light toward the laser interference unit
P is set on a table RT fixed on a fine movement stage AFS. The AF length measuring optical system has the same structure as that shown in FIG.

Also in this length measuring instrument, the same procedure as that shown in FIG.
(Refer to the figure) and the length measurement is performed. That is, each time the coarse movement stage SR and the fine movement stage AFS are moved and the fine movement stage AFS or an object to be measured such as an optical probe fixed to the fine movement stage AFS moves a predetermined unit length Δx, a pulse signal is output from the laser interference system. Is output, and the distance between these pulses is interpolated by the analog length measurement output of the AF length measurement system.
Due to this, while maintaining the accuracy of the laser interference measuring system for measuring the length of a large stroke, a higher resolution (high accuracy) measuring is realized by interpolating between the pulses of this laser interference measuring system. be able to.

FIG. 22 shows still another example related to the present invention.

In the figure, SM is a reference member provided with a diffraction grating corresponding to the diffraction grating GS of FIG. 4, and is fixed to one of two relatively moving objects. Optical components other than the reference member SM shown in the figure constitute a length measuring head optical system MH, which is integrally fixed and arranged on the other of the two objects. As shown in FIG. 23, the reference member SM is provided with a diffraction grating GS for grating interference length measurement, and parallel to the grating GS, the raised gratings GB1 and BG2 for AF length measurement and the AF length measurement reference. A flat surface FT that serves as a reflective surface is provided. The two blazed gratings BG1 and BG2 are arranged so as to be offset from each other by a half of the grating pitch p _B in the relative movement direction (direction of arrow A) between the reference member SM and the measuring head optical system MH.

In FIG. 22, the light source LD1, the half mirror HM2, the phase difference plates FP1 and FP2, the mirrors CP1 and CP2, the polarization beam splitter BS, and the photodetectors PD1 and PD2 form an interferometric length measurement optical system. The interferometric length measuring optical system and the grating interferometric length measuring grating GS on the reference member SM correspond to the optical system and sensor for generating the pulse train described in FIG.

Light source LD2, collimator lens CL, half mirror HM
11, HM12, objective lenses LN1 and LN2, and optical position detectors PS1 and PS2 form two sets of AF length measurement optical systems. Each AF length measuring optical system is configured to be optically equivalent to that described in FIG. Also, these A
As shown in FIG. 24, the F length measuring optical system is arranged so as to focus near the surfaces of the blazed gratings BG1 and BG2 on the reference member SM.

Further, the light source LD3 such as a semiconductor laser and the light spot position detection sensor PS3 are for detecting the relative inclination between the detection surface of the length measuring head optical system MH and the reference member SM. The light spot position detection sensor PS3 receives the reflected light from the area FS to obtain a parallelism detection signal between the reference member SM and the length measurement optical system MH. ing.

FIG. 25 shows pulse train signals output from the grating interferometer length measuring system of FIG. 22 and blazed gratings BG1 and B on the reference member SM.
The relationship with the cross-sectional shape of G2 (hence the output of the AF length measurement system) is shown. The pitch of the blazed gratings BG1 and BG2 is p _B , and the height difference is H. The pitch p _B is set to an even multiple, for example, 10 times the period Δx of the pulse train of the grating interference measuring system.

At the time of length measurement in this device, the pulse train of the grating interference length measurement system counts the cumulative number ... N-1, N, N + 1 ,. The AF measuring systems for measuring the surface positions of the blazed gratings BG1 and BG2 are switched to the AF measuring system on the side of the grating BG2 immediately before the step of the grating BG1, and the AF measuring system of the grating BG1 side immediately before the step of the grating BG2. Switch to long system. That is, when the relative movement of the reference member with respect to the length measuring head MH is such that the reference member SM moves in the negative direction of the x-axis in FIG. 25, as shown in FIG.
BG1 from the BG2 side at the timing of the (N-1) th pulse
The BG1 side is switched to the BG2 side at the timing of the N + 4th pulse. Reference member S
When the relative movement direction of M is the positive direction of the x-axis, the reverse direction switching is performed. The reference member SM is the measuring head optical system M.
To which direction the movement is relative to H depends on the lattice B
It can be determined by the AF length measurement signals corresponding to G1 and BG2. Therefore, the switching direction may be performed based on this discrimination information.

The output signal (AF signal) of the AF length measuring system focused near the surface of the blazed grating changes as the defocus amount of the AF length measuring optical system changes as the reference member SM relatively moves. Therefore, the movement of the reference member SM in the x-axis direction can be taken out as information in the height direction of the surface of the blazed grating. In this case, in order to use the region (see FIG. 12) where the characteristic of the AF measurement signal with respect to the defocus amount is linear, the height H of the blazed grating needs to be smaller than the height at which the linearity of the AF signal is guaranteed. There is.
For example, the differential output signal ΔI on the sensor surface of the AF system at the center of the long side of the blazed grating (see FIGS. 11 and 12).
If 0 is set to 0, that is, if focusing is performed, a signal of high and low amount δ is obtained at the position of point K in FIG.
The length in the x-axis direction from the point C to the point K is obtained as δ · H / p _B. Therefore, if the pulse train corresponding to the point C is the Nth pulse train, the position of the point K is obtained as N · Δx + δ · H / p _B.

Further, as shown in FIG. 26, the AF detection voltage V _AF at that time is stored each time a pulse signal is generated from the interferometric length measurement system,
The interpolation may be performed based on the difference voltage from the voltage V _AF until the next pulse signal is generated.

When the light for AF length measurement is incident on the blazed grating, it is preferable to set the surface between the incident light and the reflected light so as to be close to the direction perpendicular to the relative movement direction of the reference member SM.

The blazed lattice can be manufactured by a known method such as a manufacturing method by wet etching using the relationship between the crystal orientation of the Si wafer and the etching speed, a mechanical processing method by a so-called ruling engine, or a manufacturing method by lithographic and dry etching. .

The grating pitch for grating interferometry is 1.6 μm and the pulse train period of the grating interferometry is 0.4 μm.
Using objective lenses LN1 and LN2 of 0 (NA≈0.9),
As a blazed grating, pitch p _B ≈ 3 μm, height difference H ≈
The linear range of the AF signal is a little less than 1 μm when the one having a tilt angle θ of 18 ° with respect to the plane FS of 1 μm is used.
Differential output maximum value _(I A _-I B) _max is about 2Volt, noise (N) was 5 mV. The AF accuracy calculated as the differential output ΔI (S) when S / N = 1 is 0.0025 μm
Met. Also, the reference grating SM and the measuring head optical system MH
The measurement accuracy of the relative movement amount was 0.007 μm.

In this example, the large stroke length measuring device is not limited to the grating interference length measuring device, but may be another length measuring device such as a laser interference length measuring device capable of obtaining a length measurement pulse signal.

Further, in FIG. 22, each AF length measurement system is not limited to the TTL-AF system of the example, but an optical pickup system used for a DAD (Digital Audio Desk) or a video desk, or a system used for autofocus of a camera. It is also possible to use one.

Further, either the reference member SM or the length measuring head optical system MH may move, or both may move.

Further, although two rows of blazed gratings are used in the above example, as shown in FIG. 27, two autofocus probe systems PR1 and PR2 are provided in one row of blazed gratings.
May be attached. In this case, it is preferable to aim the point between the two probes that is substantially shifted by half the pitch of the blazed grating.

In the length measuring device of FIG. 22, a blazed grid pattern is provided between the pulses of a length measuring device that outputs pulse signals at intervals corresponding to a fixed length, such as a grating interference measuring device or a laser interference measuring device. High precision (high resolution) focusing on the surface shape of the member Interpolation by the length measurement value of the AF length measuring means with a small stroke keeps the high precision of the pulse generation position of the length measuring instrument that generates the pulse. As it is, the pulse interval is further decomposed to achieve high accuracy,
High-resolution measurement can be realized.

Further, since the AF length measuring means has a very small stroke of, for example, about 1 μm, in the example of FIG.
The stage with a measuring head has a two-stage structure including a moving stage SR and a fine moving stage AFS. Here, a blazed grid-like member formed by repeatedly arranging slopes having minute height differences is used to measure the moving direction of the object to be measured. Since the displacement for a small stroke is converted into the displacement in the direction intersecting with this moving direction and then the displacement is measured, if the height difference of the blazed lattice member is set to be within the stroke of the AF length measuring means, the AF means It is possible to measure the small stroke displacement amount of the large stroke movement without moving.

Further, two rows of blazed grid-like members are arranged with their step positions displaced in the movement direction, or a point of the one row of blazed grid-like members that is displaced by about a half pitch is used as a target for AF measurement, and the step of the blazed grid-like members is changed. By switching the target member or position of AF length measurement before and after, and not using the AF length measurement signal at the portion where the surface shape of the blazed grid-like member is indeterminate, higher accuracy can be achieved.

FIG. 28 shows a diffraction grating interferometer with no corner cube. In the figure, the relative movement diffraction grating GS is fixed to one of the two objects that move relative to each other, and the length measuring head unit MH is fixed to the other of the two objects.

Laser light emitted from the light source LD of the length measuring head unit MH, for example, a semiconductor laser, becomes a plane wave at the collimator lens CL, and is split into two light fluxes at the half mirror HM20. The two light beams L01 and L02 are incident on the λ / 4 plates QW1 and QW2, respectively, and then diffracted by the fixed gratings GF1 and GF2, and the ± N-order diffracted lights LN1 and LN2 enter the relative moving grating GS,
Here, it again undergoes reflection diffraction, returns in the same direction, and merges.
This light is divided by half mirrors HM21 to HM23, and a polarizing plate PP
A combination of 1 to PP4 and sensors (photodetectors) PD1 to PD4 is converted into an electric signal and taken out.

Here, the λ / 4 plate QW placed in the luminous fluxes L01 and L02
1 and QW2 are set such that the fast axes are + 45 ° and -45 ° with respect to the linearly polarized light of the laser light. The angles of the polarization plates PP1 to PP4 are set so that the polarization directions are 0 °, 45 °, 90 ° and 135 °, respectively.

Then, the amount of light incident on the sensors PD1 to PD4 changes as shown in FIG. 29 as the relative movement grating GS moves.
This is obtained as the light amount detection output. In other words, the outputs of each of the sensors PD1 to PD4 are out of phase by 90 °.

FIG. 30 shows the state of the diffracted light beam when the output wavelength of the light source LD changes in the length measuring device of FIG. In FIG. 30, the optical path of the light beam in the best adjusted state is shown by a solid line, and the optical path when the wavelength is changed is shown by a dotted line and an alternate long and short dash line. The outputs of the sensors PD1 to PD4 when there is a wavelength change are as shown in FIG. 31, and a so-called bias amount unrelated to the moving amount of the relative moving grating GS is added to this output. The reason for this is that, as shown in FIG. 30, the area of the light flux where the interference fringes do not stand other than the interference area shown by the diagonal lines increases, and the area of the area where the interference fringes do not stand changes depending on the amount of wavelength fluctuation. .
Therefore, the fluctuations shown in the output signal waveforms of the photodetectors PD1 to PD4 in FIG. 31 occur. However, when processing is performed based on four detection signals whose phase changes every 90 °, even if a wavelength change occurs, division with respect to the signal period can be performed accurately. If the sensor is 2
If only four pulses are used and two signals with phases of 0 ° and 90 ° are electrically processed, it is possible to obtain a pulse with the same pitch as when four sensors are used. , The electrical division accuracy of the obtained signal becomes poor. This is the same as described above with reference to FIGS.

Further, in the structure shown in FIG. 6, the light entering the grating GS at the point P1 changes in the diffraction direction (angle) when the wavelength of the light source LD changes.
Will change. Corresponding to this characteristic, corner cubes (prisms) CC1 and CC2 are arranged. A corner cube is a prism formed by processing the angle between the multiple surfaces to 90 ° so that the light is reflected back in the same direction as the incident light. However, this corner cube requires high precision in processing, which increases cost.

In the apparatus of FIG. 28, in addition to the moving grating GS, a diffraction grating (fixed gratings GF1 and GF2) is also provided on the side of the measuring head MH, and the ± Nth order light of the fixed grating is re-diffracted by the moving grating, and The diffracted light has the same optical path and reaches the sensor. Therefore, as described above, even without the corner cube, it is possible to obtain interference light whose brightness changes according to the movement of the moving grating even when the wavelength changes. That is, since this grating interferometer has good stability against wavelength fluctuations without a corner cube, the cost of the device can be reduced. In addition, it becomes easy to make an IC as shown below.

For example, a grating interferometer with a configuration as shown in FIG.
D, polarizing mirror BS, corner cube CC1, CC2
, The polarizing plates PP1 and PP2, the detectors PD1 and PD2, etc. are separately combined to form a three-dimensional structure. Therefore, there is a disadvantage that an error is mixed in the interference signal due to mechanical fluctuation between optical members, temperature change, and air fluctuation, which deteriorates the measurement accuracy. Further, since the light source and the detection system are separately attached, the volume occupied in space is large, and the size cannot be reduced. Furthermore, there is a problem in that noise is likely to enter due to the spatial distance from the detection system to the processing circuit, which deteriorates measurement accuracy.

FIG. 32 is a diagram showing the configuration of a length measuring apparatus according to an embodiment of the present invention in which the above-mentioned drawbacks are solved by integrating the main part of the grating diffraction length measuring device into an IC. Here, an example in which a portion corresponding to the optical system of the length measuring head portion MH of the length measuring device of FIG. 28 and a signal processing electric system for generating a pulse in accordance with the brightness of the interference light are formed on the GaAs substrate. Indicates.

A dielectric waveguide WG layer is formed on the GaAs substrate SB, and a light wave propagates through a preset optical path.

The light source LD can be formed on the GaAs substrate SB by, for example, MBE (molecular beam epitaxy). Lens and heme splitter L formed in the waveguide WG
S makes the divergent light from the light source LD parallel light and then divides it into two directions. The grating couplers GC1 and GC2 emit the light waves propagating through the thin film waveguide WG into the space at a certain angle.

The reference diffraction grating GS corresponds to the moving grating GS of the length measuring device shown in FIG. 28, and includes the grating couplers GC1 and G1.
Diffract the light wave from C2 in the same direction. The photodetector PD detects the interference light intensity of the diffracted light from the reference diffraction grating GS.

Next, the operation will be described.

The light wave from the light source LD propagates in the waveguide WG, and propagates in the waveguide WG as parallel lights L01 and L02 having two different directions by the lens and the beam splitter unit LS. The respective lights L01 and L02 are reflected in the waveguide WG by the mirrors MR1 and MR2 so as to be parallel to the longitudinal direction of the reference grating GS, and enter the grating couplers GC1 and GC2.
The grating couplers GC1 and GC2 emit the light waves, which have propagated in the waveguide WG up to that point, from the substrate surface to the outside through the waveguide surface at a certain set angle. This angle is related to the pitch of the reference grating GS and the wavelength of light, and the pitch p = 1.6
When the reference grating of μm is used, the exit angle is 58.8 ° when the wavelength is λ = 0.83 μm.

The two light waves from the grating couplers GC1 and GC2 are vertically diffracted by the reference diffraction grating GS and then detected by the photodetector PD.
to go into. The photodetector PD photoelectrically converts the interference intensity of the two diffracted lights.

Next, the operating principle of the length measuring device will be described.

The light waves emitted into space by the grating couplers GC1 and GC2 are diffracted on the reference grating GS, and the intensity distribution of the diffracted light at that time is expressed by the following formula.

Here, x is the relative change amount between the substrate and the reference grating, p is the pitch of the reference diffraction grating, m is the diffraction order at which the light from the grating coupler GC1 is diffracted by the reference diffraction grating, and n is the light from the grating coupler GC2. Is the diffraction order diffracted by.

Now, assuming that m = + 1, n = -1, and p = 1.6 μm, I becomes Therefore, it can be seen that every time the reference grating GS moves by 0.1 μm pitch, it becomes a sine wave signal of one cycle. The detector PD can measure the amount of movement of the reference grating GS by counting the period of this sine wave signal.

Since this grating interferometer length measuring device integrates a light source, an optical member, and a detection system processing circuit on the same substrate, downsizing,
Low noise and high accuracy are possible.

Next, a means for detecting the moving direction of the reference grid GS will be described.

In order to detect the moving direction, it is necessary to obtain two signals that are 1/4 cycle out of phase.

As a concrete method, for example, as shown in FIG.
S to the direction of movement (For example, if m = 1, n−1, 1/8 pitch) The phases are shifted to form two grid line arrays GL1 and GL2.
Further, two photoelectric detectors PD1 and PD2 are formed on the substrate SB in correspondence with each grid line array.

Diffracted light from each of the grid line arrays GL1 and GL2 is received by spatially separated sensors PD1 and PD2.
The signal thus obtained can be obtained as a signal with a phase shift of 1/4 period as shown in FIG.

FIG. 35 is a diagram showing the configuration of another embodiment of the present invention in which the grating interferometer is made into an optical heterodyne.

In this case, the frequency shifter FS such as SAW (S
By inserting the urface Acoustic Wave device, it is possible to obtain a light wave whose frequency is shifted by Δf which is the oscillation frequency of the oscillator OSC with respect to the frequency f ₀ of the output light from the light source LD. These frequencies f ₀ and f
Each of the ₀ + Δf light waves is grating coupler GC1.
And the grating line array is incident on the reference grating GS of one row via GC2 and the diffracted light by the reference grating GS is received by the photodetector PD.

The signal obtained directly at the photodetector PD is Therefore, by detecting the phase difference with the output signal of the oscillator OSC by the phase detection circuit PSD, the movement amount and the movement direction of the reference grating GS can be detected as in the above-described embodiment.

The feature of this device is that it is not necessary to use a special grid for discriminating directions (for example, see FIG. 33), and time averaging can be performed in a shorter time, so that the movement amount can be detected with high accuracy.

In addition, in the IC for length measuring instrument of FIGS. 32 and 35,
A GaAs substrate is used as the substrate SB.
i It may be on the substrate. In that case, the light source LD is externally attached.

In this way, by integrating the optical system other than the reference grating and the signal processing electric system on a single board in the grating interferometer, it is unnecessary to assemble and adjust, and it is resistant to disturbance, small and lightweight, and highly accurate. It is possible to measure length.

[Brief description of drawings]

FIG. 1 is a schematic view of a length measuring apparatus related to the present invention, FIG. 2 is a partially enlarged view of an arrangement space for optical probes and the like in FIG. 1, and FIG. 3 is a schematic view of the present invention set on a uniaxial stage. FIG. 4 is a schematic configuration diagram of a related length measuring device, FIG. 4 is a configuration explanatory diagram of the length measuring head in FIG. 3, FIG. 5 is an output waveform diagram of the photodetector in FIG. 4, and FIG. FIG. 4 is an explanatory view of the action of the grating interferometric length measuring system, FIG. 7 is an explanatory view of polarization azimuth rotation of the detection light in the configuration of FIG. 6, and FIG. 8 is the phases 0 ° and 180 in the configuration of FIG. Signal waveform diagram of °, Fig. 9 is a diagram showing an example of the configuration for extracting signals of phases 0 ° and 180 ° in the configuration of Fig. 6, and Fig. 10 is a function of the AF length measuring system in Fig. 4. Fig. 11 and Fig. 11 show the spot state and light quantity on the position sensor surface with respect to the position of the plane mirror in Fig. 10. Shows a fabric, FIG. 12 is a characteristic diagram showing the relationship between the position of the differential signal ΔI (= I A _{-I B)} and the plane mirror that is created from the output of the position sensor (defocus amount), FIG. 13 is a flowchart showing the operation of the length measuring device of FIG. 3, FIG. 14 is an output signal characteristic diagram of the grating interference measuring system in the length measuring device of FIG. 3, and FIG. 15 is FIG. Fig. 16 is a diagram showing the output signal characteristics of the AF length measuring system in the length measuring device, Fig. 16 is a block diagram showing an embodiment in which the length measuring unit is put together, and Fig. 17 shows the operation of the length measuring unit shown in Fig. 16. FIG. 18 is a characteristic diagram showing the relation between the grating interference measurement pulse signal and the AF measurement output voltage in the length measuring unit of FIG. 16, and FIG. 19 shows the length measuring unit of FIG. Fig. 20 is a schematic configuration diagram when it is used for two axes, and Fig. 20 shows an example of using a laser interferometer as the interferometer. Fig. 21 is a diagram showing details of the length measurement optical system on the fine movement stage in Fig. 20, Fig. 22 is a constitution diagram of an example of AF length measurement using a blazed grating, Fig. 23 Is a perspective view of the reference member on which the blazed grating is formed, FIG. 24 is an explanatory view showing a positional relationship between the blazed grating and the AF length measuring system in FIG. 22, and FIG. 25 is a grating in FIG. A characteristic diagram showing the relationship between the output pulse train signal of the interferometric measuring system and the output of the AF measuring system, FIG. 26 shows the relationship between the reference member position and the AF measuring signal switching state in the modified example of FIG. Explanatory diagram showing, FIG. 27 is an explanatory diagram showing the positional relationship between the blazed grating and the AF length measuring system in another modification of the example of FIG. 20, FIG. 28 is a book constructed without using a corner cube Fig. 29 is a block diagram of a diffraction grating interferometer according to the present invention. Output waveform diagram of the detector, Fig. 30 is an explanatory diagram showing the state of the diffracted light flux when the output wavelength of the light source changes in the length measuring device of Fig. 28, and Fig. 31 shows the light source wavelength fluctuation in Fig. 28. 32 is an output waveform diagram of each photodetector at the time, FIG. 32 is a configuration diagram of a grating diffraction side length measuring device according to an embodiment of the present invention in which a main part is integrated, FIG. 33 is a length measuring device of FIG. FIG. 34 is an enlarged view of an essential part showing a modified example of FIG. 34, FIG. 34 is an output waveform diagram of each photodetector in the length measuring device of FIG. 33, and FIG. 35 is still another modification of the length measuring device of FIG. , DS: Stage base XS: X stage YS: Y stage LI: Laser interferometer, CP: Corner cube prism DV: Optical probe placement space DFS: Small stroke stage base XFS: Small stroke X stage YFS Small stroke Y stage LP: Optical probe SX: x direction Standard scale HX: x-direction length measurement head MX: x-coordinate detection length measurement device SY: y-direction reference scale HY: y-direction length measurement head MY: y-coordinate detection length measurement device SR: moving stage GS: diffraction grating (reference Scale, moving grid) MH: Length measuring head SP: Surface plate PM: Planar mirror AFS: Fine movement stage (AF stage) FD: Fine drive mechanism LD: Light source CL: Collimator lens HM: Beam splitter (or half mirror) CC: Corner Cube prism (or prism mirror) BS: Polarizing beam splitter PD: Photodetector (detector, photosensor) LN: Objective lens PS: Optical position detector (sensor) ST: Stage moving part QW: λ / 4 plate GL: Collection Optical lens SS: Stage fixed part AT: Actuator MO: Object to be inspected OS: Measurement reference plane ED: Signal processing electrical system PC: Pulse train length measuring device Electric system FF: Focus detection system CPU: Central control calculation system LZ: Laser head IU: Interference unit SM: Reference member BG: Blazed grating FT: Plane serving as a reflection surface FP: Phase difference plate GF: Fixed grating PP: Polarizing plate SB: GaAs substrate WG: Dielectric waveguide layer LS: Lens and Heme splitter part GC: Grating coupler FS: Frequency shifter OSC: Oscillator PSD: Phase detection circuit MR: Mirror WP: Wollaston prism AP: aperture

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukichi Niwa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP 61-196119 (JP, A) JP 59 -218915 (JP, A) JP-A-57-207805 (JP, A)

Claims (8)

[Claims] 1. A light source for generating a light flux and a surface are arranged so as to face a diffraction grating as a standard scale, and are arranged so as to be movable relative to the diffraction grating in a substantially arrangement direction of the diffraction grating. And a waveguide layer provided on the surface of the substrate facing the diffraction grating and guiding the light flux along the facing surface, and a light flux from the light source provided on the waveguide layer. An optical integrated circuit provided with means for splitting into a light flux and means for emitting each of the split light fluxes from the waveguide layer toward a specific location in space by deflecting each of the split light fluxes in a direction intersecting with the facing surface; A displacement measuring device, comprising: a light detecting unit that receives light beams emitted from a waveguide layer and diffracted by the diffraction grating and interfering with each other. 2. The displacement measuring device according to claim 1, wherein the substrate is a GaAs substrate. 3. The displacement measuring device according to claim 1, wherein the substrate is a Si substrate. 4. A photoelectric conversion unit that detects diffracted light that is vertically diffracted from the diffraction grating to the substrate and interferes with each other and is incident on the optical integrated circuit, and a processing circuit that processes an output of the photoelectric conversion unit. The displacement measuring device according to claim 2 or 3, including the claims. 5. The displacement measuring device according to claim 2, wherein the light source is included in the optical integrated circuit. 6. A pitch corresponding to 1/4 cycle of a cycle of light-dark change of the interference light, which is determined by an optical arrangement such as a deflection state of the light and an order of the diffracted light, wherein two rows of grating lines are provided in the diffraction grating. 7. The interfering light caused by the diffracted light from each lattice line array is separately detected by displacing only in the relative movement direction, and the light detecting means separately detects the interference light.
Displacement measuring device described in. 7. The optical integrated circuit detects a frequency shifter that shifts the frequency of one of the two light fluxes by Δf, and a phase difference of the output of the photodetection means with respect to the transition frequency Δf, and detects the phase difference. The displacement measuring device according to any one of claims 1 to 5, further comprising means for detecting a moving amount and a moving direction. 8. A light source for generating a light beam, a base body whose surface is disposed so as to face an object whose displacement is to be measured, and which is arranged so as to be movable relative to the object, and the object of the base body. A light guide layer provided on the surface facing the light guide and guiding the light flux along the light facing surface, means for dividing the light flux from the light source and dividing the light flux into two light fluxes, and each light flux divided. And an optical integrated circuit provided with means for emitting light from the waveguide layer toward a specific location in space by deflecting the light beams in a direction intersecting with the facing surface, respectively, and emitted from the waveguide layer and acted by the object. Further, the displacement measuring device is provided with a light detecting means for receiving lights that interfere with each other.