WO2007074752A1

WO2007074752A1 - Tilt sensor and encoder

Info

Publication number: WO2007074752A1
Application number: PCT/JP2006/325712
Authority: WO
Inventors: Toru Imai; Akihiro Watanabe
Original assignee: Nikon Corporation; Sendai Nikon Corporation
Priority date: 2005-12-28
Filing date: 2006-12-25
Publication date: 2007-07-05
Also published as: JP2007178281A

Abstract

An optical unit (26) is provided with a first diffraction grating (127a) and a second diffraction grating (127b) which is arranged at a position at a prescribed distance from the first diffraction grating in a Z axis direction. The status of light interfered by both the first diffraction grating and the second diffraction grating of the optical unit change corresponding to relative angle change of illuminating light projected from a light source and the optical unit. Therefore, relative angle relationship between the illuminating light and the optical unit can be measured by receiving the interference light by a light receiving element.

Description

Specification

Chino Reto Sensor and Encoder

Technical field

The present invention relates to a tilt sensor and an encoder, and more particularly to a tilt sensor that measures a relative tilt amount between illumination light and a diffraction grating, and an encoder including the tilt sensor.

Background art

Conventionally, for example, an optical encoder described in Patent Document 1 has been used to measure the position of a test object.

[0003] This optical encoder uses the intensity of illumination light that has passed through both a moving diffraction grating that moves with a moving object and a fixed index diffraction grating as information indicating the relative positional deviation between the two diffraction gratings. This encoder is a so-called diffraction interference encoder.

[0004] Such an optical encoder can only measure the position in the direction in which the grating is arranged. However, recently, it is considered necessary to measure the rotation of the test object (the tilt direction of the moving grid that moves with the test object with respect to the plane on which the grid is formed).

[0005] Also, for example, as described in Patent Document 2, if the incident angle of light incident on a diffraction grating for generating three beams of a modulation encoder can also be measured, accurate position measurement by the modulation encoder is realized. It becomes possible.

[0006] Patent Document 1: JP 2005-55360 A

Patent Document 2: U.S. Pat.No. 6,639,686

Disclosure of the invention

Means for solving the problem

[0007] The present invention has been made under the circumstances described above. From the first viewpoint, a light source that emits illumination light; a first diffraction grating; and the first diffraction grating, An optical unit having a second diffraction grating arranged in a predetermined positional relationship with respect to the optical path direction of the illumination light. And a light receiving element that receives light interfering with the optical unit and outputs a signal related to a relative angle change between the illumination light and the optical unit.

[0008] According to this, the state of the light that interferes with the first diffraction grating and the second diffraction grating of the optical unit changes according to the relative angle change between the illumination light and the optical unit, and the interference A signal relating to the relative change in angle between the illumination light and the optical unit is output from the light receiving element that has received the light. Therefore, the relative angular relationship between the illumination light and the optical unit can be detected based on the signal.

[0009] According to a second aspect of the present invention, there is provided a light source that emits illumination light; an arbitrary light source provided with a diffraction grating on a surface on the light source side, and a reflective film formed on a surface on the opposite side. An optical element having a refractive index; after passing through the diffraction grating, receiving the light reflected by the reflection film and passing through the diffraction grating again, and changes the relative angle between the illumination light and the optical element. And a light receiving element that outputs a signal related to the second tilt sensor.

[0010] According to this, the light that has passed through the diffraction grating, reflected by the reflective film, and again passed through the diffraction grating in accordance with the relative angle change between the illumination light incident on the optical element and the optical element. The state of the light changes, and a signal relating to the relative angle change between the illumination light and the optical unit is output from the light receiving element that receives the light. Therefore, the relative angular relationship between the illumination light and the optical unit can be detected based on the signal.

[0011] According to a third aspect of the present invention, there is provided an encoder for irradiating illumination light onto a pattern arranged along a predetermined direction and detecting the pattern, the first diffraction grating, and the first An optical unit having a second diffraction grating disposed in a predetermined positional relationship with respect to the optical path direction of the illumination light; and receiving the illumination light that has passed through the optical unit and entering the optical unit A light-receiving element that outputs a signal related to a relative angle change between the illumination light and the optical unit.

[0012] According to this, the light receiving element force for receiving the light diffracted by the first and second diffraction gratings is output according to the relative angle change between the illumination light incident on the optical unit and the optical unit. Since the signal changes, the relationship between the optical unit and the illumination light can be adjusted according to the signal. Therefore, after adjustment, the position meter using the optical unit that interferes with the illumination light By performing measurement, it becomes possible to perform highly accurate position measurement.

According to the fourth aspect of the present invention, in the encoder that irradiates illumination light to a pattern arranged along a predetermined direction and detects the pattern, the first and second tilt sensors of the present invention are used. It is the 2nd encoder provided with.

[0014] According to this, the encoder that measures the position in the in-plane direction perpendicular to the optical axis of the illumination light detects the relative angular change between the optical unit or optical element having the diffraction grating and the illumination light. Since the first and second tilt sensors of the present invention that can be used are provided, the optical unit or the optical element can be adjusted according to the detected angle change. Therefore, it is possible to perform highly accurate position measurement by performing position measurement after adjustment.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing a tilt sensor according to a first embodiment.

2] FIG. 2 (A) and FIG. 2 (B) are diagrams for explaining the principle of the optical unit of FIG.

FIG. 3 is a schematic diagram showing an encoder according to a second embodiment.

4 is a diagram showing a configuration of the light receiving element in FIG. 3.

FIG. 5 (A) and FIG. 5 (B) are diagrams showing modifications of the tilt sensor.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] First Embodiment

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 2B.

FIG. 1 schematically shows a tilt sensor 100 according to the first embodiment. This tilt sensor 100 has light sources 12 arranged in sequence in the Z-axis direction (up and down direction in FIG. 1).

0, a collimator lens 121, an optical unit 26, and a light receiving element 136 are included.

As the light source 120, for example, a short wavelength band VCSEL (surface emitting laser) can be employed. This surface emitting laser is a near-infrared surface emitting semiconductor laser capable of high-speed driving with high uniformity and a large-scale array.

The collimator lens 121 converts the laser light emitted from the light source 120 into parallel light.

[0020] The optical unit 26 comprises a glass plate force that transmits laser light, and measures a tilt amount. Connected to the test object (moving body). On the surface of the glass plate on the light source 120 side, as shown in an enlarged view in FIG. 2A, a light source side grating 127a is provided, and on the back surface (surface on the light receiving element 136 side), the light receiving element side is provided. A grid 127b is provided. These gratings 127a and 127b are line 'and' space patterns in which a plurality of line patterns whose longitudinal direction is the X-axis direction are arranged in the Y-axis direction, and the pitch of the light source side gratings 127a is, for example, 25. For example, the pitch of the light receiving element side grating 127b is 25.6 m.

Returning to FIG. 1, the light receiving element 136 is composed of a multi-part light receiving element.

According to the tilt sensor 100 configured as described above, the laser light emitted from the light source 120 is converted into parallel light by the collimator lens 121 and enters the optical unit 26. The laser light incident on the optical unit 26 interferes as follows.

[0023] 02 (A) shows a state in which the laser beam is incident on the upper surface of the optical unit 26 perpendicularly! In this case, the optical unit 26 generates a plurality of diffracted lights at the light source side grating 127a based on the incident parallel light. Figure 2 (A) shows the ± 1st-order diffracted light generated at the three points (points A, B, and C) of the source-side grating 127a.

[0024] Of these, paying attention to the + first-order diffracted light generated at point A, this + first-order diffracted light further generates a plurality of diffracted lights at the AB point of the light receiving element side grating 127b. Here, in Fig. 2 (A), only the ± 1st-order diffracted light is shown (not shown in parentheses). Of these, the solid line in Fig. 2 (A) contributes to interference. Described—first-order diffracted light. On the other hand, for the first-order diffracted light generated at point A, a plurality of diffracted lights are further generated at the AC point of the light receiving element side grating 127b. Here, in Fig. 2 (A), only the ± 1st-order diffracted light is shown (shown without parentheses), but the contribution to interference is shown by the solid line in Fig. 2 (A). It is + first order diffracted light.

Next, paying attention to the first-order diffracted light generated at point B, this first-order diffracted light further generates a plurality of diffracted lights at point AB of the light receiving element side grating 127b. Here, in Fig. 2 (A), only ± 1st-order diffracted light is shown (shown in parentheses), but the one that contributes to interference is shown by the solid line in Fig. 2 (A). It is + first order diffracted light. The +1 next-order diffracted light interferes with the first-order diffracted light generated at the AB point of the light receiving element side grating 127b out of the + first-order diffracted light generated at the point A described above. Next, focusing on the + first-order diffracted light generated at point C, this + first-order diffracted light further generates a plurality of diffracted lights at the AC point of the light receiving element side grating 127b. Here, in Fig. 2 (A), only ± 1st-order diffracted light is shown (shown in parentheses), but the one that contributes to interference is shown by the solid line in Fig. 2 (A). Has been the first-order diffracted light. This first-order reflected light interferes with the + first-order diffracted light generated at the AC point of the light receiving element side grating 127b among the first-order diffracted light generated at the point A described above.

In this way, interference fringes are formed on the light receiving element 136 due to the interference of the laser light that has passed through the optical unit 26.

FIG. 2B shows a state in which the laser light is incident on the upper surface of the optical unit 26 at an angle slightly inclined from the vertical. In FIG. 2 (B), the force that shows the state in which the angle of the optical unit 26 is the same and the laser beam is tilted as compared to FIG. 2 (A) is shown. The same concept can be applied when the optical unit 26 is tilted.

In this case, the optical unit 26 generates a plurality of diffracted lights at the light source side grating 127a based on the incident parallel light. In FIG. 2B, among the diffracted lights, the light source side grating 127a Only ± 1st order diffracted light generated at 3 points (A, B, D, C, D) is shown.

As shown in FIG. 2 (B), the + first-order diffracted light generated at the point A is diffracted again at the point AB ′ of the light receiving element side grating 127b, and ± 1st-order diffracted light (FIG. 2 (B ) Is shown without parentheses). In this case, the first-order diffracted light indicated by the solid line contributes to the interference. On the other hand, the first-order diffracted light generated at point A is diffracted again at point AC ′ of the light-receiving element side grating 127b, and ± 1st-order diffracted light (shown without parentheses in FIG. 2 (B)) appear. In this case, the + first-order diffracted light indicated by the solid line contributes to interference.

[0031] As can be seen from FIG. 2B, the optical path lengths in the glass plate of the + first-order diffracted light generated at point A and the first-order folded light are different.

[0032] Similarly, the first-order diffracted light of the first-order diffracted light generated by diffraction at the B, point of the light source side grating 127a is diffracted again at the AB 'point of the light-receiving element side grating 127a, and ± 1st order diffracted light (Indicated by parentheses). Of these, the + next-fold light shown by the solid line interferes with the first-order diffracted light generated via points A and AB 'described above. [0033] On the other hand, the + first-order diffracted light of the first-order diffracted light generated by diffraction at the point C at the light source side grating 127a is diffracted again at the AC 'point of the light-receiving element side grating 127a, and ± 1 (Shown in parentheses). Of these, the first-order diffracted light indicated by the solid line interferes with the + first-order diffracted light generated via points A and AC 'described above.

In this case, as compared with 02 (A) and FIG. 2 (B), the relative angle between the optical axis of the laser beam and the optical unit 26 varies, so that the corresponding interference light Is shifted in the Y-axis direction (Y direction in this embodiment), that is, the interference intensity of the interference fringes changes. The light receiving element 136 detects the interference intensity of the generated interference fringes and outputs a signal including the amount of movement of the interference fringes on the light receiving surface to a control device (not shown). In the tilt sensor 100 of this embodiment, the origin of measurement does not exist, but in the initial adjustment, the optical unit 26 is in a desired state (for example, as shown in FIG. The position of the interference fringes when it is set to the vertical incident state) is regarded as the origin, and a deviation from the origin is detected.

[0035] Here, as in the present embodiment, when a scale in which a grating is arranged on the front and back surfaces of a glass plate is employed, the light source side grating 127a is regarded as an index scale and the light receiving element side grating 127b is regarded as a moving scale. Can think. That is, if the moving scale is tilted and the light beam exit position changes by 1 pitch (25.6 m), the propagation angle inside the glass is 0 ', the glass thickness is t, and the lattice pitch is p. It becomes a relationship like Formula (1).

[0036] tan Θ '= p / t… hi)

Since the above equation (1) relates to the inside of the glass, if the refractive index is 1.5 and the actual inclination of the optical unit 26 is Θ, the following equation (2) is obtained.

[0037] sin Θ / sin θ '= 1.5

sin 0 = 1.5 sin [tan— ¹ (p / t)] · · · (2)

Here, if the lattice pitch is 25.6 / ζ πι and the glass thickness is 3 mm, Θ = 44 (min). Therefore, since one cycle of the interference fringes corresponds to 44 minutes, the resolution is 44 X 607512 = approximately 5.16 (seconds) when the number of interpolations of the light receiving element 136 is 512. Further, since a multi-segment light receiving element is adopted as the light receiving element 136, a two-phase signal can be obtained by detecting values of points having different 90 ° phases, and the inclination direction can also be measured. [0038] It should be noted that, by using the method of this embodiment, the optical path length difference between the ± 1st order diffracted lights does not occur due to the inclination, so that the initial condition of Talbot (Talbot) interference is maintained even if the inclination occurs It is possible to perform stable tilt measurement without changing.

[0039] As described above in detail, according to the tilt sensor of the first embodiment, the optical unit 26 includes the light source side grating 127a and the light source side grating 127a with respect to the Z-axis direction. The light receiving element side grating 127b provided at a distance is provided, and the light source side grating 127a of the optical unit 26 and the light receiving element are changed according to a relative angle change between the laser beam and the optical unit 26. Since the intensity of the interference fringes diffracted by the side grating 127b changes, the relative angular relationship between the laser beam and the optical unit 26 can be measured by detecting the interference fringes with the light receiving element 136. It becomes.

In the present embodiment, since the pitches of the light source side grating 127a and the light receiving element side grating 127b are different, the interval (pitch) of interference fringes is increased. For example, when the pitch of the light source side grating 127a is 25.0 m and the pitch of the light receiving element side grating 127b is 25.6 μm as in the present embodiment, the interference fringes with a pitch of about 0.8 mm are used. Will occur. Therefore, since the pitch of the interference fringes used for tilt measurement is large, a change in the intensity of the interference fringes (movement of the interference fringes on the light receiving surface of the light receiving element 136) can be accurately detected. Thereby, it is possible to improve the tilt measurement accuracy.

[0041] << Second Embodiment >>

Next, an encoder according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows a schematic configuration of the encoder 17 of the second embodiment.

The encoder 17 includes a scale 18 that extends in the Y-axis direction, and a probe unit 19 that emits a beam probe. The scale 18 is formed with a reflective diffraction grating (grating 1) having periodicity in the Y-axis direction. As shown in Fig. 3, this diffraction grating is an uneven surface type diffraction grating. The pitch (cycle) is the same in all sections.

The probe unit 19 includes a laser diode 20, a bending mirror 22 disposed on the + Y side of the laser diode 20, and an optical element disposed on the + Z side of the bending mirror 22 in sequence. Unit 26, beam splitter 28, objective lens 30, lens 32 and optical sensor 34 disposed on the + Y side of beam splitter 28, and light receiving element 36 disposed on the Y side of beam splitter 28 .

The laser diode 20 emits laser light having a wavelength of 640 nm, for example.

The bending mirror 22 has a function as a vibrating mirror that is vibrated by a driving device 24 including, for example, a piezo element, and the angle of the bending mirror 22 can be adjusted by the driving device 24. A control device (not shown) adjusts the angle of the reflecting surface of the mirror 22 with respect to the laser light emitted from the laser diode 20 via the driving device 24 to a desired angle.

[0046] The optical unit 26 has the same force as that of the optical unit in the tilt sensor 100 described above. Here, the light source side grating has a main beam of 0th-order diffracted light and ± 1 based on the incident laser light. Generates two sub-beams of next diffracted light. The relationship between the main beam and the two sub-beams is the relationship in which the main beam is positioned between the two sub-beams along the grating arrangement direction when these beams are irradiated onto the scale. .

The optical sensor 34 is composed of a CCD or the like, and the light receiving element 36 is the same as the light receiving element 136 of the tilt sensor 100 described above, and outputs a detection signal to a control device (not shown).

[0048] In the encoder 17 configured as described above, the laser light emitted from the laser diode 20 is reflected by the folding mirror 22 by approximately 90 °, enters the optical unit 26, and the optical unit 26 After being split into two sub-beams, the beam passes through the beam splitter 28 and reaches the grating 1 on the scale 18 by the objective lens 30. Then, the laser light reflected on the grating 1 passes through the objective lens 30, is reflected by the beam splitter 28, and is received by the optical sensor 34 via the lens 32. A signal from the optical sensor 34 is sent to a control device (not shown). The principle and circuit configuration of signal detection in this control device are disclosed in detail in Japanese Patent Publication No. 2000-511634 and US Pat. No. 6,639,686. To the extent permitted by national legislation in the designated country (or selected selected country) designated in this international application, the disclosure in the above US patent specification is incorporated and made a part of this description.

[0049] It should be noted that the optical sensor 34 has two sub-beams, a main beam of 0th order diffracted light and a first order diffracted light. Light is received in a state of being divided into frames. Therefore, when such a probe unit is adopted, as the optical sensor 34, as shown in FIG. 4, a four-part optical sensor 34 for main beam detection and two sensors 34, 34 for sub-beam detection Can be used.

3 1 2

[0050] The result of receiving two sub-beams, that is, the detection signal of the optical sensor 34, 34 force

1 2

From either one, it is possible to detect the relative distance between the peak of grating 1 and the vibration center of the beam probe. Light sensor 34, 34 signal force is also detected amplitude and

1 2

The result of adding the phase detection value is detected as the measurement value of the encoder, and the result of subtraction is detected as the drift amount of the beam probe due to laser diode position drift.

[0051] If the output of each sensor of the quadrant optical sensor 34 is a, b, c, d, for example, the detection result of the main beam indicates that two signals (a + b + c + d, a + c— b— d) can be created. Since these two signals have a phase difference of 90 degrees, these two signals are sent to the control device and used for focus control between the objective lens 30 and the grating 1.

[0052] In this manner, the probe unit 19 outputs laser light toward the scale 18, the laser light (beam probe) reflected on the grating 1 of the scale 18 is received by the optical sensor 34, and the light reception result is obtained. The corresponding signal is output.

Incidentally, as can be seen from FIG. 3, the laser light that passes through the optical unit 26 and is reflected by the beam splitter 28 is incident on the light receiving element 36. Therefore, in the probe unit 19 of the encoder 17 in FIG. 3, the laser diode 20 corresponds to the light source 120 of the tilt sensor 100 in FIG. 1, the light receiving element 36 corresponds to the light receiving element 136 in FIG. Since this is the same as the optical unit 26 of the tilt sensor 100, the tilt sensor 100 ′ having the same function as the tilt sensor 100 of FIG. From the tilt sensor 100, the relative angle between the optical unit 26 and the laser beam incident on the optical unit 26 can be detected. Therefore, the control device adjusts the angle of the laser light incident on the optical unit 26 by adjusting the angle of the bending mirror 22 via the drive device 24 based on the detection result by the tilt sensor 100 ′. As a result, the laser light can be incident on the optical unit 26 at an ideal angle, so that the measurement by the encoder 17 can be performed with high accuracy. [0054] Since a main beam and two sub beams are generated from the optical unit 26, the relative angle of these beam forces may be obtained, or one of the three beams is used. V, you can also find the relative angle!

[0055] As described above, according to the encoder of the present embodiment, the tilt sensor 100 'capable of measuring the relative angular relationship between the laser beam and the optical unit 26 is included. The angular relationship between the laser beam and the optical unit 26 can be adjusted based on the detection result by the sensor 100 ′. As a result, position measurement by the encoder can be performed accurately over a long period of time.

[0056] Further, according to the present embodiment, since the optical unit 26 force provided in the probe unit 19 of the encoder 17 has a function for measuring the inclination of the optical unit 26, the number of parts can be reduced. Therefore, the enlargement of the encoder itself can be suppressed.

In the second embodiment, a reflection type diffraction grating is used as the scale 18. However, the present invention is not limited to this, and a transmission type diffraction grating may be used. In this case, the lens 32 and the optical sensor 34 are arranged on the + Z side of the scale 18.

It should be noted that the encoder of the second embodiment can also be employed in a diffraction interference type or shadow picture type encoder.

Furthermore, the optical unit 26 of the second embodiment can be used as the scale 18 of the encoder.

[0060] In each of the above embodiments, the force of using a glass plate as the optical unit 26 is not limited to this, and any material having an arbitrary refractive index is not limited to glass. Absent. For example, a diffraction grating may be formed in a semiconductor or the like.

In each of the above embodiments, the case where the grating pitch of the light source side grating 127a and the light receiving element side grating 127b provided in the optical unit 26 is slightly different (25.0 m and 25.6 m) will be described. However, the present invention is not limited to this, and both gratings may have the same pitch.

In each of the above embodiments, the case where the light source side grating 127a and the light receiving element side grating 127b are provided on the front and back surfaces of the glass plate has been described, but the present invention is not limited to this. For example, it is possible to adopt an optical unit 26 ′ having the configuration shown in FIG. . In this case, the optical unit 26 can be fixed to the object to be measured, for example.

[0063] As shown in Fig. 5 (A), this optical unit 26 'also has a glass plate force,

Diffraction grating 127 'force is provided on the + Z side surface, and reflective film 129 is provided on the Z side surface

According to the optical unit 26 ′ configured in this manner, the obliquely incident laser light is diffracted by the diffraction grating 127, and ± 1st order diffracted light is generated. These ± 1st-order diffracted light and 0th-order light are totally reflected by the reflection film 129 and diffracted again by the diffraction grating 127 ′. Here, the light shown by the solid line in FIG. 5 (A) contributes to the interference.

[0065] Here, the principle is the same when comparing Fig. 5 (B), which shows the unfolded state with respect to the reflecting surface, and Fig. 2 (A), Fig. 2 (B). Even in this case, it is clear that the same interference as in the above embodiment occurs.

Therefore, as in FIGS. 2A and 2B, the diffracted light of the laser light diffracted at other points (diffracted by the diffraction grating 127 ′, and then reflected by the reflective film 129, Interference fringes are formed on a light receiving element (not shown) provided behind the optical path.

[0067] In this case as well, as in the above-described embodiment, the position of the interference fringe on the light receiving element changes when the incident angle of the laser beam to the optical unit changes. Thus, it is possible to detect the incident angle of the laser beam with respect to the optical unit. Industrial applicability

[0068] As described above, the tilt sensor of the present invention is suitable for measuring the relative angle between the illumination light and the optical unit. The encoder of the present invention is suitable for pattern detection.

Claims

The scope of the claims

[1] a light source that emits illumination light;

An optical unit comprising: a first diffraction grating; and a second diffraction grating disposed in a predetermined positional relationship with respect to the first diffraction grating in the optical path direction of the illumination light;

A tilt sensor comprising: a light receiving element that receives light that has interfered with the optical unit and outputs a signal related to a relative angle change between the illumination light and the optical unit.

[2] In the tilt sensor according to claim 1,

The optical unit includes a member having an arbitrary refractive index, and the first diffraction grating and the second diffraction grating are formed on the member.

[3] In the tilt sensor according to claim 2,

The member is a plate-like member capable of transmitting the illumination light,

The first diffraction grating is formed on a surface of the plate-like member on the light source side, and the second diffraction grating is formed on a surface of the plate-like member opposite to the light source side.

[4] The tilt sensor according to claim 3,

A tilt sensor in which the grating pitch of the first diffraction grating and the grating pitch of the second diffraction grating are the same or slightly different.

[5] The tilt sensor according to claim 3,

The first diffraction grating and the second diffraction grating have the same grating pitch, and the light receiving element detects a change in the incident angle of the illumination light with respect to the optical unit.

[6] In the tilt sensor according to claim 2,

The member is a tilt sensor made of glass.

[7] The tilt sensor according to claim 1,

The light receiving element is a tilt sensor which is a multi-part light receiving element.

[8] a light source that emits illumination light;

An optical element having an arbitrary refractive index, in which a diffraction grating is provided on the surface on the light source side, and a reflective film is formed on the surface on the opposite side; A light receiving element that receives the light reflected by the reflective film after passing through the diffraction grating and again passed through the diffraction grating, and that outputs a signal relating to a relative angle change between the illumination light and the optical element; A tilt sensor.

[9] The tilt sensor according to claim 8,

[10] An encoder for irradiating illumination light to a pattern arranged along a predetermined direction and detecting the pattern,

An encoder comprising the tilt sensor according to any one of claims 1 to 9.

[11] The encoder according to claim 10,

An encoder that uses a diffraction grating of an optical unit constituting the tilt sensor as a diffraction grating for measuring the position of a test object.

[12] An encoder for irradiating illumination light onto a pattern arranged along a predetermined direction and detecting the pattern,

An optical unit comprising: a first diffraction grating; and a second diffraction grating arranged in a predetermined positional relationship with respect to the optical path direction of the illumination light with respect to the first diffraction grating;

An encoder comprising: a light receiving element that receives illumination light that has passed through the optical unit, and that outputs a signal relating to a relative angle change between the illumination light incident on the optical unit and the optical unit.

[13] The encoder according to claim 12,

The optical unit has a plate-like member on which the first diffraction grating and the second diffraction grating are formed,

The pattern is an encoder formed on the plate-like member.