JPH08240408A - Displacement sensor - Google Patents

Abstract

PURPOSE: To accurately obtain the amount of displacement by correcting the amount of displacement obtained by a displacement measuring optical system by the amount of inclination of a detection object obtained by an inclination measuring optical system. CONSTITUTION: The displacement measuring light rays 15 emitted from a displacement measuring light-projecting element 18 are converged by a converging lens 20 and are thrown on the surface of an detection object 1 after passing through a dichroic mirror 17. The displacement measuring light rays 15 reflected by the detection object 1 are converged by a light-receiving lens 23, and made to selectively pass through a dichroic mirror 24, and are imaged on a displacement measuring light-receiving element 21. The inclination measuring light rays 16 whose wavelength is different from that of the displacement measuring light rays 15 emitted from an inclination measuring light-projecting element 19 are collimated by the converging lens 20 and are thrown on the surface of the detection object 1 after being reflected by the dichroic mirror 17. The inclination measuring light rays 16 reflected by the detection object 1 are converged by the light-receiving lens 23 and are selectively reflected by the dichroic mirror 24 and are converged on an inclination measuring light-receiving element 22.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a displacement sensor. In particular, the present invention relates to a displacement sensor for measuring the displacement of a detection object having a substantially specularly reflecting surface such as a mirror surface object, a glossy material object, and a metal object.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing a configuration of an optical system in a displacement sensor A of this type, in which a displacement amount d of a detection object 1 is measured by using a triangulation method. The light source 3 includes a light emitting element 4 such as a light emitting diode (LED) and a light projecting lens 5.
And the optical axes 6 thereof are aligned with each other. The light receiving section 7 includes a light receiving lens 8 and a position detecting element (PSD).
And the like, and their optical axes 10 are made to coincide with each other. The light source 3 and the light receiving portion 7 are symmetrically arranged on both sides of the standard line SL, and both the optical axis 6 of the light source 3 and the optical axis 10 of the light receiving portion 7 are at the same angle with respect to the standard line SL. It is α. Here, the standard line SL indicates a reference position for measuring the displacement of the detection object 1, and the displacement amount d of the detection object 1 is a displacement distance on the standard line SL. Is defined as In addition, the optical axis 6 of the light source 3 and the optical axis 10 of the light receiving unit 7 are the standard line S.
A point on the standard axis SL that intersects at one point on L and the optical axes 6 and 10 intersect is called a standard point SP, and a standard point S
A plane that passes through P and is perpendicular to the standard line SL will be referred to as a standard plane SF. The distance between the light emitting element 4 and the light projecting lens 5 is equal to the measuring light 2 emitted from the light emitting element 4 and condensed by the light projecting lens 5.
Is adjusted so as to be condensed at one point at the standard point SP, and the measuring light 2 reflected at the standard point SP is condensed at the light receiving lens 8 and condensed on the light receiving element 9. The distance between the light receiving lens 8 and the light receiving element 9 is adjusted.

When the measuring light 2 emitted from the light emitting element 4 is condensed by the light projecting lens 5 and applied to the surface of the detection object 1, the measuring light 2 is condensed at one point at the standard point SP. To do.
At this time, the detection object 1 (A) on the standard surface SF [hereinafter, the position of the surface of the detection object 1 is referred to as the position of the detection object 1]. ], The measuring light 2 specularly reflected by the surface of the detection object 1 is imaged on the light receiving element 9 through the light receiving lens 8 as shown by the solid line in FIG. To form a light receiving spot.

On the other hand, in the case of the detection object 1 (B) displaced from the standard surface SF, the measuring light 2 is condensed on the light receiving element 9 through the light receiving lens 8 as shown by the broken line in FIG. Since the light receiving spot generated as a result moves, the displacement amount d of the detection object 1 is detected by detecting the moving amount (distance from the point on the optical axis to the position of the center of gravity of the light receiving intensity) x of the light receiving spot.
Can be calculated. That is, if the distance between the standard point SP and the light-receiving lens 8 is a, the distance between the light-receiving lens 8 and the light-receiving element 9 is b, and the movement amount of the light-receiving spot is x, the detection object 1 with reference to the standard surface SF The displacement amount d can be obtained by the principle of triangulation method and is represented by the following equation.

[0005]

[Equation 1]

[0006]

However, in the displacement sensor A as described above, the detection object 1 displaced in the direction of the standard line SL and further tilted with respect to the standard line SL.
In the case of (C), as shown by the chain double-dashed line in FIG. 1, the light receiving spot on the light receiving element 9 further moves, and the output from the light receiving element 9 changes. Moreover, the displacement amount d and the inclination amount β
It was also not possible to separately detect and.

As described above, the movement amount x of the light receiving spot is not limited to the displacement amount d of the detection object 1 but also the inclination amount β of the detection object 1.
Even when the amount x of movement of the light receiving spot on the light receiving element 9 is the same, the detected object 1 has no inclination (β = 0) and has an inclination (β ≠ 0). The actual displacement amount d of the detected object 1 also depends on the magnitude of the inclination amount β.
Will be different. Therefore, when detecting the displacement of the detection object 1 that may be inclined, a measurement error occurs in the displacement amount d due to the inclination of the detection object 1, which causes a decrease in the measurement accuracy of the displacement sensor A. Was there.

The present invention has been made in view of the drawbacks of the above conventional examples, and an object thereof is to provide an inclination measuring optical system to a displacement sensor so that the inclination can be measured simultaneously with the displacement. Further, it is an object of the present invention to correct the measured displacement amount of the detected object by using the inclination of the detected object detected by the inclination measuring optical system so that the displacement amount can be measured with high accuracy.

[0009]

DISCLOSURE OF THE INVENTION The displacement sensor according to claim 1 of the present invention receives a displacement measuring light source for emitting displacement measuring light toward a detection region and a displacement measuring light reflected by the detection region. And a tilt measuring optical system for detecting the tilt of the object in the detection area.

Therefore, the displacement measuring light emitted from the displacement measuring light source unit is applied to the detection object. The displacement measuring light reflected by the detection object is imaged on the displacement measuring light receiving section. Therefore, the displacement amount of the detected object can be known from the image forming position of the displacement measuring light receiving section. Further, since this displacement sensor is provided with the tilt measuring optical system, the tilt amount of the detected object can be simultaneously measured. Moreover, since the displacement measuring optical system and the tilt measuring optical system can be integrated as a displacement sensor, the displacement sensor having the tilt measuring optical system can be downsized.

According to the second aspect of the invention, based on the output information from the tilt measuring optical system,
It is characterized by further comprising correction means for correcting the output information of the displacement measuring optical system.

Although the displacement amount measurement result is affected by the tilt amount of the detection object, the inclination amount measurement result is not affected by the displacement amount of the detection object, so that the tilt amount can be accurately detected. Therefore, according to this embodiment, if the displacement amount is corrected using the inclination amount measured at the same time as the displacement amount measurement, the displacement amount that is not affected by the presence or absence of the inclination and its size can be obtained with high accuracy.

Moreover, since the displacement measuring optical system and the inclination measuring optical system are integrated, the displacement amount and the inclination amount can be measured at the same time, and the reliability of measurement and correction can be improved. .

According to another aspect of the present invention, the tilt measuring optical system includes a tilt measuring light projecting element for emitting tilt measuring light, and a tilt emitted from the tilt measuring light projecting element. An inclination measuring projection lens that collimates the measuring light and irradiates the detection object, a tilt measuring light receiving lens that collects the tilt measuring light reflected by the detection object, and a focus position of the light receiving lens It is composed of a tilt measuring light receiving element.

Thus, the tilt measuring light emitted from the tilt measuring light projecting element is converted into collimated light by the tilt measuring light projecting lens, irradiated on the detection object, and reflected by the detection object. Is condensed on the light receiving element for tilt measurement through the light receiving lens for tilt measurement. Therefore, the amount of tilt of the detected object can be known from the light receiving position of the light receiving element for tilt measurement. Moreover, the collimated light is applied to the detection object,
Since the light receiving element for tilt measurement is arranged at the focal position of the light receiving lens for tilt measurement, the tilt amount can be independently measured with high accuracy without being affected by the displacement of the detection object.

According to another aspect of the present invention, the tilt measuring optical system includes a tilt measuring light projecting element for emitting a laser beam, which is tilt measuring light, toward a detection object, and the detection object. It is composed of a tilt measuring light receiving lens for refracting the tilt measuring light reflected by and a tilt measuring light receiving element arranged at the focal position of the light receiving lens.

Therefore, the laser light emitted from the light-projecting element for tilt measurement (light for tilt measurement) is applied to the detection object,
The laser beam reflected by the detection object is focused on the light receiving element for tilt measurement through the light receiving lens for tilt measurement. Therefore, the amount of tilt of the detected object can be known from the light receiving position of the light receiving element for tilt measurement. Moreover, since the laser beam is used as the tilt measuring light and the tilt measuring light receiving element is arranged at the focal position of the tilt measuring light receiving lens, the tilt amount is independently increased without being affected by the displacement of the detected object. It can be measured with accuracy. Further, by using the laser light as the tilt measuring light, the tilt measuring light projecting lens can be eliminated, the structure of the tilt measuring optical system can be simplified, and the displacement sensor can be reduced in size and weight and cost. .

According to the fifth aspect of the invention, the inclination measuring light receiving lens also serves as the light receiving lens of the displacement measuring light receiving section.

Therefore, according to this embodiment, the number of parts can be reduced and the cost of the displacement sensor can be reduced by using the displacement measuring optical system and the tilt measuring optical system as a light receiving lens. Further, by also using the light receiving lens, the number of parts of the light receiving lens can be reduced and the displacement measuring light receiving element and the tilt measuring light receiving element can be arranged close to each other, and the displacement sensor can be made extremely small and lightweight. it can.

According to the sixth aspect of the invention, the tilt measuring light projecting lens also serves as the light projecting lens of the displacement measuring light source section.

Therefore, according to this embodiment, the number of parts can be reduced by also using the light projecting lens, and the cost of the displacement sensor can be reduced. Further, by also using the light projecting lens, the number of parts of the light projecting lens can be reduced and the displacement measuring light source and the tilt measuring light source can be arranged close to each other, and the displacement sensor can be made extremely small and lightweight. it can.

According to the seventh aspect of the present invention, the displacement measuring light source section has a light projecting lens, the displacement measuring light receiving section has a light receiving lens, and the displacement measuring light receiving section has a light receiving lens. The aperture diameter of the lens is larger than the aperture diameter of the projection lens for displacement measurement.

The smaller the diameter of the light projecting lens, the deeper the depth of focus of the displacement measuring light with which the detection object is irradiated, the smaller the change in the spot diameter on the detection object even when the detection object moves, and the light receiving for displacement measurement. Image on the device (received light intensity pattern)
Blurring is less likely to occur. On the other hand, it is preferable that the light receiving lens is large so that the displacement measuring light can be received even when the detected object is inclined. Therefore, it is desirable that the diameter of the light receiving lens is at least equal to or larger than the diameter of the light projecting lens.

According to the embodiment of the present invention, the light spot generated on the surface of the detection object by the displacement measuring light is inside the light spot generated on the surface of the detection object by the inclination measuring light. It has a feature.

Since the displacement measuring light and the inclination measuring light are applied to the same portion of the detected object, the displacement measurement and the inclination measurement can be performed at the same portion, and the displacement correction accuracy is improved. Further, displacement measurement and tilt measurement can be performed even for a small detection object.

Further, in the embodiment described in claim 9, the displacement measuring light and the inclination measuring light have different wavelengths from each other.

By using the displacement measuring light and the inclination measuring light having different wavelengths, it is possible to accurately perform the displacement measurement and the inclination measurement without interfering with each other.

For example, as in the embodiment described in claim 10, the displacement measuring light and the inclination measuring light having different wavelengths emitted from the light source side of the displacement measuring light source section and the inclination measuring optical system are photosynthesized. By irradiating the detection object with a device overlapping each other, both measurement points can be made to coincide with each other, so that the displacement correction accuracy is improved. Further, when the light projecting lens is used, the light projecting lens can be shared. Moreover, since the wavelengths are different even when the two measuring lights are superposed, the measurement results can be separately separated and taken out.

That is, as in the eleventh aspect of the present invention, the displacement measuring light and the tilt measuring light having different wavelengths which are overlapped with each other are separated by the wavelength separator, and the displacement measuring light is guided to the displacement measuring light receiving section. If the tilt measuring light is guided to the light receiving side of the tilt measuring optical system, the displacement amount and the tilt amount can be accurately measured without causing interference between the displacement measuring optical system and the tilt measuring optical system. be able to.

Further, in the twelfth aspect of the present invention, both the displacement measuring light and the inclination measuring light are polarized lights, and their polarization directions are different from each other. .

According to this embodiment, by using the displacement measuring light and the tilt measuring light having different polarization directions, the displacement measuring and the tilt measuring can be performed accurately without interfering with each other.

For example, as in the embodiment described in claim 13, the displacement measuring light and the inclination measuring light emitted from the light source side of the displacement measuring light source and the inclination measuring optical system and having different polarization directions are different from each other. By irradiating the detection object with overlapping with a photosynthesiser, both measurement points can be matched,
The displacement correction accuracy is improved. Further, when the light projecting lens is used, the light projecting lens can be shared. Moreover, since the polarization directions are different even when the two measurement lights are superposed, the measurement results can be separated and taken out separately.

That is, as in the embodiment of claim 14, the displacement measuring light and the inclination measuring light, which have different polarization directions and are overlapped with each other, are separated by using a polarization separator, and the displacement measuring light is received by the displacement measuring light. If the light for tilt measurement is guided to the light receiving side of the tilt measurement optical system, the displacement amount and tilt amount can be accurately measured without causing interference between the displacement measurement optical system and the tilt measurement optical system. It can be measured well.

According to the embodiment of claim 15,
It is characterized in that an aperture stop having a small aperture is provided at the incident side focal position of the tilt measuring projection lens.

According to this embodiment, however, since the tilt measuring light incident on the light projecting lens can be made into a point light source, the collimating accuracy of the tilt measuring light passing through the light projecting lens can be improved. Therefore, the light can be accurately focused on the optical axis on the light receiving element for tilt measurement, and the tilt measurement accuracy can be improved.

According to the embodiment of claim 16,
It is characterized in that an aperture stop for limiting the beam size of the tilt measuring light is provided on the incident side of the tilt measuring light projecting lens.

However, according to this embodiment, since the beam size of the tilt measuring light can be reduced by the aperture stop, it is suitable for measuring a small detection object.

[0038]

FIG. 2 shows a displacement sensor B according to an embodiment of the present invention.
It is a figure which shows the optical system of. Where SL, SF, SP
1 represent a standard line, a standard surface, and a standard point, respectively, as in FIG. It is α. The light projecting unit 11 is an optical combiner for aligning the displacement measuring light source unit, the tilt measuring light source unit, and the displacement measuring light 15 and the tilt measuring light 16 emitted from both light source units with their optical axes aligned. (17) and.

The displacement measuring light source unit includes a light emitting diode (L
Displacement measuring light emitting element 18 such as ED) and light emitting lens (2
0) and the light source unit for tilt measurement includes a light projecting element 19 for tilt measurement such as a light emitting diode (LED) and a light projecting lens (20). The light projecting lens of the light source is a single projecting lens 20.
It is also used by. Here, the light emitting element 1 for displacement measurement
The wavelength of the displacement measuring light 15 emitted from 8 and the wavelength of the inclination measuring light 16 emitted from the inclination measuring light projecting element 19 are different from each other. For this purpose, for example, as the displacement measuring light projecting element 18 and the inclination measuring light projecting element 19, light emitting diodes having different emission wavelengths may be used. Alternatively, filters having different transmission wavelengths may be provided between the displacement measuring light projecting element 18 and the light combiner (17) and between the inclination measuring light projecting element 19 and the light combiner (17).

The optical combiner used in this embodiment is an optical element for superimposing a plurality of lights (having different wavelengths) and outputting them. In this embodiment, a dichroic mirror 17 is used. This dichroic mirror 17
Indicates a high transmittance for the light in the wavelength range of the displacement measuring light 15 and a high reflectance for the light in the wavelength range of the tilt measuring light 16, and is provided on one side of the dichroic mirror 17. Displacement measuring light projecting element 18 is arranged, and tilt measuring light projecting element 19 is arranged on the other side. Displacement measuring light 15 emitted from displacement measuring light projecting element 18 and transmitted through dichroic mirror 17 and tilt measuring light Inclination measuring light 1 emitted from the light projecting element 19 and reflected by the dichroic mirror 17
6 and 6 are coaxially overlapped with each other, and then the detection object 1 is irradiated through the light projecting lens 20.

The dichroic mirror 17 has a high reflectance for the light in the wavelength range of the displacement measuring light 15 and a high transmittance for the light in the wavelength range of the tilt measuring light 16. It may be provided, and in that case, the displacement measuring light projecting element 18 and the tilt measuring light projecting element 19 are arranged as shown in FIG.
The opposite is true. Further, the optical combiner here is not limited to the dichroic mirror, and for example, a half mirror or the like may be used although the efficiency is lowered. Also, various optical multiplexers for optical communication can be used.

In this light projecting section 11, the light source section for displacement measurement is a condensing system, and the light 15 for displacement measurement emitted from the light projecting element 18 for displacement measurement is dichroic mirror 1.
After passing through 7, the light is condensed by the projection lens 20, and the standard point S
It converges on P. Therefore, the displacement measuring light projecting element 18 and the light projecting lens 20 are arranged with their optical axes 12 aligned with each other, and the distance (optical path length) between them is longer than the focal length of the light projecting lens 20. . Further, the tilt measuring light source unit is a collimating system, and the tilt measuring light 16 emitted from the tilt measuring light projecting element 19 is reflected by the dichroic mirror 17 and then collimated by the light projecting lens 20 to collimate the collimated light. The detection object 1 is illuminated as Therefore, the inclination measuring light projecting element 19
And the projection lens 20 are arranged with their optical axes 12 aligned with each other, and the distance (optical path length) between them is equal to the focal length of the projection lens 20.

The light receiving portion 13 of the displacement sensor B includes a light receiving element 21 for displacement measurement such as a position detection element (PSD) and a charge coupled device (CCD), a light receiving element 22 for tilt measurement, and a light receiving element for displacement measurement and tilt measurement. The light receiving lens 23 also serves as a light receiving lens 23, and a wavelength separator (24) for separating the displacement measuring light 15 and the tilt measuring light 16 which are overlapped with each other. The wavelength separator of this embodiment is an optical element that separates and outputs a plurality of overlapping lights of different wavelengths. In this embodiment, a dichroic mirror 24 is used as in the case of the optical combiner. The dichroic mirror 24 shown in FIG.
Also has a high transmittance for the light in the wavelength range of the displacement measuring light 15 and a high reflectance for the light in the wavelength range of the tilt measuring light 16, and the optical axis 14 on the transmission side The displacement measuring light projecting element 18 is arranged on the upper side, and the tilt measuring light receiving element 22 is arranged on the reflection-side optical axis 14. Then, when the displacement measuring light 15 and the tilt measuring light 16 reflected by the detection object 1 pass through the light receiving lens 23 and enter the dichroic 24 while overlapping each other, the displacement measuring light 1
Reference numeral 5 passes through the dichroic mirror 24 and enters the displacement measuring light receiving element 21, and the tilt measuring light 16 is reflected by the dichroic mirror 24 and enters the tilt measuring light receiving element 22.

The dichroic mirror 24 of the wavelength separator also shows a high reflectance for the light in the wavelength range of the displacement measuring light 15 and a high transmittance for the light in the wavelength range of the tilt measuring light 16. The arrangement of the displacement measuring light receiving element 21 and the inclination measuring light receiving element 22 is opposite to that shown in FIG. The wavelength separator is not limited to the dichroic mirror, but a half mirror having no wavelength discriminating property cannot be used alone. However, a half mirror and a wavelength selection filter can be used in combination. Also, various optical demultiplexers for optical communication can be used.

In this light receiving section 13, the displacement measuring light receiving section consisting of the displacement measuring light receiving element 21 and the light receiving lens 23 is an image forming system, and the displacement measuring light reflected specularly on the surface of the detection object 1 is used. After being condensed by the light receiving lens 23, the light 15 is transmitted through the dichroic mirror 24 and condensed on the displacement measuring light receiving element 21. Therefore, the light receiving lens 23 and the displacement measuring light receiving element 21 are arranged with their optical axes 14 aligned with each other, and the distance (optical path length) between the light receiving lens 23 and the displacement measuring light receiving element 21 is the focal point of the light receiving lens 23. It is longer than the distance f. In particular, the light reflected at the standard point SP is designed to converge at a point on the optical axis 14 of the displacement measuring light receiving element 21 (coordinate origin on the displacement measuring light receiving element 21). The distance from the standard point SP is a,
Assuming that the distance (optical path length) between the light receiving lens 23 and the displacement measuring light receiving element 21 is b and the focal length of the light receiving lens 23 is f, the distance between them is (1 / a) + (1
There is a relationship of / b) = (1 / f). The tilt measuring light receiving section includes a tilt measuring light receiving element 22 and a light receiving lens 23, and tilt measuring light (collimated light) 16 reflected by the surface of the detection object 1 is collected by the light receiving lens 23. , Is reflected by the dichroic mirror 24 and is condensed on the inclination measuring light receiving element 22. Therefore, the light receiving lens 23 and the inclination measuring light receiving element 22 are arranged with their optical axes 14 aligned, and the distance (optical path length) between them is equal to the focal length f of the light receiving lens 23. The tilt measuring light 16 parallel to the light receiving lens 2 is provided on the light receiving element 22 for tilt measuring.
The light is focused on the focal point position 3 (the coordinate origin of the light receiving element 22 for tilt measurement).

Therefore, in this displacement sensor B, the displacement measuring optical system is composed of the displacement measuring light-projecting element 18, the light-projecting lens 20 (also used), the light-receiving lens 23 (also used) and the displacement-measurement light-receiving element 21. Constituting light source 1 for tilt measurement
9. Light projecting lens 20 (also used), light receiving lens 23 (also used)
The tilt measuring optical system is constituted by the tilt measuring light receiving element 22, and the displacement measuring optical system and the tilt measuring optical system are optically separated and independent from each other.
Structurally integrated, it is compactly constructed with a small number of parts.

First, the displacement sensor B detects the object 1 to be detected.
The principle of measuring the inclination of is explained. Of the displacement sensor B, only the tilt measuring optical system is taken out and shown in FIG. 3 (the effect of the dichroic mirrors 17 and 24 is omitted). Since the tilt measuring light projecting element 19 is arranged at the focal point of the light projecting lens 20, the tilt measuring light 16 emitted from the tilt measuring light projecting element 19 passes through the light projecting lens 20 to become collimated light. It is projected on the surface of the detection object 1.
When the detection object 1 is not tilted (β = 0), the tilt measurement light 16 reflected by the surface of the detection object 1 (A) enters the light receiving lens 23 as collimated light parallel to the optical axis 14. Since the tilt measuring light 16 is condensed at the focal point of the light receiving lens 23, the origin position of the tilt measuring light receiving element 22 (y =
0) to collect a light receiving spot.

On the other hand, when the detected object 1 is inclined by β,
Since the tilt measuring light 16 reflected by the surface of the detection object 1 (B) is tilted by 2β with respect to the optical axis 14, as can be seen from FIG. 3, the light receiving spot focused at the position of the focal length f is y from the origin position. = F · tan (2β) ... Therefore, the tilt amount β of the detection object 1 (B) can be obtained by detecting the movement amount y of the light receiving spot on the tilt measuring light receiving element 22.

On the other hand, when the detection object 1 moves in parallel while maintaining a constant inclination amount β, the angle 2β of the inclination measuring light 16 reflected by the detection object 1 with respect to the optical axis 14 does not change, so the inclination The position [y = f · tan (2β)] of the light receiving spot on the measuring light receiving element 22 does not change. That is, the tilt measuring optical system can accurately detect only the tilt amount β without being affected by the displacement amount d of the detection object 1.

Next, the displacement sensor B detects the object 1 to be detected.
The principle of measuring the displacement of is explained. Of the displacement sensor B, only the displacement measuring optical system is taken out and shown in FIG. 4 (the effect of the dichroic mirrors 17 and 24 is omitted). The displacement measuring light 15 emitted from the displacement measuring light projecting element 18 is condensed by the light projecting lens 20 to form a standard point SP.
Therefore, if the detection object 1 is on the standard surface SF, the displacement measuring light 15 reflected by the surface of the detection object 1 is condensed by the light receiving lens 23, and the origin (x A light receiving spot occurs at = 0). In addition, the detection object 1
Is displaced by d, a mirror image of the standard point SP is generated at a position 2d from the standard point SP, so that the light receiving spot on the displacement measuring light receiving element 21 moves by x as shown in FIG. If the movement amount x of the light receiving spot on the displacement measuring light receiving element 21 is detected, the displacement amount d of the detection object 1 is determined from the image formation relationship.
Can be requested. However, in the case of the displacement measuring optical system, as described in the conventional example, the movement amount x of the light receiving spot is also influenced by the inclination amount β of the detection object 1.

As described above, the measurement result of the displacement amount by the displacement measuring optical system, that is, the value of the movement amount x is a function of the displacement amount d and the inclination amount β of the detection object 1, but the inclination amount β is It can be accurately and independently obtained by the tilt measuring optical system. Therefore, if the inclination amount β is obtained from the movement amount y of the light receiving spot on the inclination measuring light receiving element 22, the displacement amount is accurately calculated from the movement amount x and the inclination amount β of the light receiving spot on the displacement measuring light receiving element 21. d can be obtained.

FIG. 5 shows a state in which the detection object 1 is displaced by d on the standard axis SL and is tilted by β.
At this time, a mirror image of the standard point SP of the detection object 1 tilted by β forms an image at the position x from the origin on the displacement measuring light receiving element 21. The distance between this mirror image and the light-receiving lens 23 is a + 2d
cos β cos (α + β), the distance between the mirror image and the optical axis 14 is 2 dco
Since it is sβsin (α + β), the movement amount x is represented by the following formula from the relationship of image formation.

[0053]

[Equation 2]

Here, assuming that the movement amount d is sufficiently smaller than the distance a between the standard point SP and the light receiving lens 23, and 2d << a, the above equation becomes simple as the following equation.

[0055]

(Equation 3)

Therefore, the displacement amount d of the detected object 1 is the movement amount x
And can be obtained from the following equation.

[0057]

[Equation 4]

FIG. 6 is a block diagram showing an example of the signal processing circuit of the displacement sensor B. The movement amount calculation circuit 27 obtains the movement amount y of the light receiving spot from the output of the inclination measuring light receiving element 22. Then, the inclination amount calculation circuit 28 uses the movement amount y calculated by the movement amount calculation circuit 27 based on the above equation, for example.
The inclination amount β of the detection object 1 is obtained from The calculated inclination amount β is output to the displacement amount calculation unit 26 and the outside. Further, the movement amount calculation circuit 25 obtains the movement amount x of the light receiving spot from the output of the displacement measuring light receiving element 21. Next, the displacement amount calculation circuit 26 uses the movement amount calculation circuit 2 based on the above equation, for example.
The displacement amount d of the detection object 1 is obtained from the movement amount x obtained in 5 and the inclination amount β obtained by the inclination amount calculation circuit 28. The calculated displacement amount d is output. As a result, the displacement sensor B can output the displacement amount d and the inclination amount β obtained with high accuracy.

FIG. 7 is a diagram showing changes in the spot diameter on the detection object 1 in the displacement measuring optical system and the received light intensity distribution on the displacement measuring light receiving element 21. That is, 29a, 2
Reference numerals 9b and 29c denote spot diameters on the detection object 1 when the detection object 1 is at the positions of d = -D, 0, + D.
0a, 30b, 30c are detected objects 1 d = -D, 0,
The light reception intensity distribution on the displacement measuring light receiving element 21 at the + D position is shown. Numerical aperture N of the projection lens 20
If A is small, the projected spot diameters 29a, 29b, 29
Although c becomes large, the depth of focus becomes small and the changes in the spot diameters 29a, 29b, 29c become large within the displacement measurement range. Therefore, the change in the spot diameter when the detected object 1 is displaced becomes large like 29a, 29b, and 29c in FIG. 7, and the images on the displacement measuring light-receiving element 21 become as in 30a, 30b, and 30c in FIG. Blurring occurs, which is one of the causes of displacement measurement error. Therefore, make sure that the projected spot diameter does not change within the displacement measurement range, or
It is necessary to reduce the change in the projected spot diameter. Therefore, if the aperture diameter of the light projecting lens 20 is reduced (the numerical aperture NA is increased), the light receiving element 2 for displacement measurement is measured.
The effect of preventing blurring of the image on 1 can be obtained. On the other hand, in the displacement measuring light receiving portion, the aperture diameter of the light receiving lens 23 needs to be large so that the displacement can be detected even if the detected object 1 is tilted. Therefore, it is desirable that the aperture diameter of the light receiving lens 23 is at least equal to or larger than the aperture diameter of the light projecting lens 20.

FIG. 8 is a schematic diagram showing a displacement sensor C according to another embodiment of the present invention. In this displacement sensor C, the dichroic mirror 17 is used to superimpose the displacement measuring light 15 and the tilt measuring light 16, and the measurement range is set to the displacement measuring light 15
Is limited to the range in which the light spreads and does not spread outside the tilt measurement light 16 so that the displacement measurement light 15 is always inside the tilt measurement light 16. Therefore, the displacement measurement position and the inclination measurement position of the detection object 1 can be matched, and the displacement amount d can be accurately corrected by the inclination amount β. In particular, even in the case of a small detection object 1, it is possible to reliably measure the inclination amount β and correct the displacement amount d, and the reliability of the measurement result is improved. Further, in the displacement sensor C, the tilt measuring light projecting element 19 and the tilt measuring light receiving element 22 are arranged closer to the center (on the standard axis SL side) than the displacement measuring light projecting element 18 and the displacement measuring light receiving element 21. The outer dimensions of the displacement sensor B are reduced.

FIG. 9 is a diagram showing a displacement sensor D according to still another embodiment of the present invention. In this displacement sensor D, an aperture stop 31 is provided at the light emission port of the inclination measuring light projecting element 19, that is, at the focal position of the light projecting lens 20. Then, by projecting the tilt measuring light 16 through the pinhole 32 of the aperture stop 31, the tilt measuring light projecting element 19 can be regarded as a point light source, and the collimating property of the tilt measuring light 16 is improved, and the tilt measuring light 16 is improved. Object 1 when there is no
The reflected light from can be focused on the focal point of the light receiving lens 23, that is, on the small area of the origin of the tilt measuring light receiving element 22. That is, the blur of the light receiving spot can be reduced.

FIG. 10 is a diagram showing a displacement sensor E according to still another embodiment of the present invention. In the displacement sensor E, an aperture stop 33 is provided in the middle of the tilt measuring light projecting element 19 and the dichroic mirror 17 at a position apart from the tilt measuring light projecting element 19 by a predetermined distance. Aperture stop 3
The incident pupil of the light projecting lens 20 can be made smaller by emitting the tilt measuring light 16 through the opening 34 of the third lens, and the beam size of the tilt measuring light 16 can be reduced.
Can be smaller than the opening diameter of. Therefore, this displacement sensor E
Is suitable for use in detecting a small detection object 1.

FIG. 11 shows a displacement sensor F according to another embodiment of the present invention. In this embodiment, an aperture stop 35 having a conical aperture 36 that is pinhole-shaped at one end is used in the inclination measuring light source unit. Therefore, according to the aperture stop 35, it is possible to reduce the blur of the light receiving spot and the beam size of the displacement measuring light 15.

FIG. 12 is a diagram showing a displacement sensor G according to still another embodiment of the present invention, which is a polarization beam splitter instead of an optical combiner such as the dichroic mirrors 17 and 24 or a wavelength separator. It uses a simple photosynthesizer and a polarization separator. In this displacement sensor G, the displacement measuring light projecting element 18 and the tilt measuring light projecting element 19 are used.
The linearly polarized displacement measuring light 15 and the tilt measuring light 16 are emitted from both of the above, and the polarization directions of the displacement measuring light 15 and the tilt measuring light 16 are orthogonal to each other. Alternatively, the displacement measuring light emitting element 18 and the tilt measuring light emitting element 1
The displacement measuring light 15 and the tilt measuring light 16 may be polarized by providing polarizers in the vicinity of the light exit port of 9 with their polarization directions orthogonal to each other.

The light projecting section 11 of the displacement sensor G uses an optical combiner (38) to superimpose the displacement measuring light 15 and the inclination measuring light 16 having different polarization directions. The optical combiner referred to here is an optical element for superimposing a plurality of lights (polarized light) and outputting them, and a polarization beam splitter (PBS) 38 is used in this embodiment. The polarization beam splitter 38 is an optical element that transmits polarized light in a certain direction and reflects polarized light in another orthogonal direction. In FIG. 12, the displacement measuring light 15 is transmitted and the tilt measuring light 1 is transmitted.
6 is reflected. Therefore, the displacement measuring light 15 emitted from the displacement measuring light projecting element 18 passes through the polarization beam splitter 38, and the tilt measuring light 16 emitted from the tilt measuring light projecting element 19 is reflected by the polarization beam splitter 38. The light 15 for displacement measurement and the light 16 for tilt measurement
Are coaxially overlapped and irradiated on the surface of the detection object 1. Of course, the displacement measuring light projecting element 18 and the tilt measuring light projecting element 19 may be arranged in reverse.

In the light receiving section 13, the displacement measuring light 15 and the tilt measuring light 16 reflected by the detection object 1 are made incident on the polarization separator (39). The polarization separator is a component that reflects light of one polarization direction and transmits light of the other polarization direction among polarized lights orthogonal to the polarization direction,
Here, the polarization beam splitter 39 is used.
Therefore, the displacement measuring light 15 and the tilt measuring light 16 which are overlapped are separated by the polarization beam splitter 39, the displacement measuring light 15 is transmitted and made incident on the displacement measuring light receiving element 21, and the tilt measuring light 16 is reflected. Then, it is made incident on the light receiving element 22 for inclination measurement, and the displacement amount d and the inclination amount β can be separated and measured.

A half mirror or the like can also be used as the photosynthesizer. Also, as this polarization separator, a half mirror alone cannot be used, but a half mirror and an analyzer can be used in combination.

As described above, the polarization beam splitter 38,
In the displacement sensor using the optical combiner or polarization separator such as 39, various embodiments similar to the displacement sensor using the optical combiner such as the dichroic mirrors 17 and 24 or the wavelength separator are possible. For example, the displacement sensor H shown in FIG. 13 is similar to the optical sensor E of FIG. 10 in that the aperture stop 33 reduces the aperture stop of the light source for tilt measurement and the beam size of the light 16 for tilt measurement is reduced. . The displacement sensor I shown in FIG. 14 is the optical sensor F shown in FIG.
Similarly to the above, the aperture stop 35 is used to incline the light emitting element 19 for tilt measurement.
Is a point light source and the beam size of the tilt measuring light 16 is reduced.

FIG. 15 is a schematic block diagram showing an optical system of a displacement sensor J according to still another embodiment of the present invention. In this displacement sensor J, the displacement measuring optical system and the tilt measuring optical system are separated. That is, the displacement measuring light projecting lens 20a and the tilt measuring light projecting lens 20b are separately used without being used in common, and the displacement measuring light receiving lens 23a and the tilt measuring light projecting lens 23b are also used separately, and are used in displacement measuring The light 15 and the tilt measuring light 16 are made to irradiate the detection object 1 from different angles. In this embodiment, light having different wavelengths is used as the displacement measuring light 15 and the inclination measuring light 16, and a wavelength selection filter 40 that transmits only the displacement measuring light 15 is provided on the front surface of the displacement measuring light receiving element 21. On the front surface of the light receiving element 22 for tilt measurement, the wavelength selection filter 4 that transmits only the light 16 for tilt measurement is placed.
1 is arranged to optically separate the displacement measuring optical system and the tilt measuring optical system.

Further, FIG. 16A is a schematic plan view showing an optical system of a displacement sensor K according to still another embodiment of the present invention, and FIG. 16B is a sectional view taken along line XX of FIG. 16A. 16 (c) is a sectional view taken along line YY of FIG. 16 (a). In the displacement sensor K, the displacement measuring optical system and the tilt measuring optical system are separated from each other as in the displacement sensor J of FIG. 15, and the displacement measuring optical system and the tilt measuring optical system are approximately 90 degrees from each other. Configured in different directions.

Laser light may be used as the displacement measuring light and the inclination measuring light. The displacement sensor L shown in FIG. 17 is an example in which laser light is used as the inclination measuring light 16a. A laser oscillator such as a helium-neon (He-Ne) laser or a semiconductor laser element (LD) is used as the inclination measuring light projecting element 19a for emitting a laser beam.
An optical conduit such as an optical fiber for guiding the laser light output from the laser oscillator can be used. A dichroic mirror 17 that transmits the displacement measuring light 15 and reflects the tilt measuring light 16a is disposed on the side closer to the detection area than the displacement measuring light projecting lens 20a. Further, a dichroic mirror 24 that transmits the displacement measuring light 15 and reflects the tilt measuring light 16a is arranged between the light receiving lens 23 and the displacement measuring light receiving element 21, and the tilt measuring light receiving element 22 is It is provided at a position of a focal length f from the light receiving lens 23. Then, the tilt measuring light (laser light) 16 a emitted from the tilt measuring light projecting element 19 a is reflected by the dichroic mirror 17, and the displacement measuring light projecting lens 20.
The displacement measuring light 15 which is condensed by a and is transmitted through the dichroic mirror 17 is superposed on the detection object 1 to be irradiated therewith, and reflected by the detection object 1. Of the displacement measuring light 15 and the inclination measuring light 16a having different wavelengths, the displacement measuring light 15 passes through the light receiving lens 23, and then passes through the dichroic mirror 24 to be received by the displacement measuring light receiving element 21. On the other hand, the tilt measuring light 16a passes through the light receiving lens 23, is reflected by the dichroic mirror 24, and is received by the tilt measuring light receiving element 22. Also in this tilt measuring optical system, the tilt measuring light receiving element 22 includes the light receiving lens 23.
Since the position of the light receiving spot does not change due to the displacement (parallel movement) of the detection object 1 and the position of the light receiving spot changes only by the tilt of the detection object 1, the tilt amount is β can be separated from the displacement amount d and measured independently. Also, the inclination measuring light 16a
By using a laser beam as the above, it is possible to eliminate the need for a light receiving lens in the tilt measuring optical system.

FIG. 18 is a diagram showing a displacement sensor M according to still another embodiment of the present invention, in which a laser beam is used as the displacement measuring light 15a. A helium-neon (He-Ne) laser, a semiconductor laser element (L) is also used as the displacement measuring light emitting element 18a for emitting a laser beam.
It is possible to use a laser oscillator such as D) or an optical conduit such as an optical fiber for guiding the laser light output from the laser oscillator. In this embodiment, the tilt measuring light projecting element 19 is arranged at the focal point of the tilt measuring light projecting lens 20b, and the dichroic mirror 17 is arranged closer to the detection area than the tilt measuring light projecting lens 20b. ing. The dichroic mirror 17 transmits the tilt measuring light 16 and reflects the displacement measuring light 15a. Further, the tilt measuring light receiving element 22 is arranged at the focal point of the tilt measuring light receiving lens 23b, and the tilt measuring light 16 is transmitted to the side closer to the detection area than the tilt measuring light receiving lens 23b to measure the displacement. A dichroic mirror 24 that reflects the light 15a is arranged. Then, the displacement measuring light 15a (laser light) emitted from the displacement measuring light projecting element 18a is reflected by the dichroic mirror 17, and the inclination measuring light projecting lens 20 is reflected.
The tilt measuring light 16 collimated by b and transmitted through the dichroic mirror 17 is superposed on the detection object 1 and is reflected by the detection object 1. Of the displacement measuring light 15a and the tilt measuring light 16 having different wavelengths, the tilt measuring light 16 passes through the dichroic mirror 24, then passes through the tilt measuring light receiving lens 23b, and is received by the tilt measuring light receiving element 22. It On the other hand, the displacement measuring light 15a is reflected by the dichroic mirror 24 and received by the displacement measuring light receiving element 21. When the detection object 1 is displaced, the displacement measuring light 15a reflected by the detection object 1 moves in parallel and the position of the light receiving spot changes, so that the displacement amount d can be measured. Further, by using laser light as the displacement measuring light 15a, it is possible to eliminate the need for a light projecting lens and a light receiving lens in the displacement measuring optical system.

FIG. 19 shows a displacement sensor N using laser light as the displacement measuring light 15a and the inclination measuring light 16a, and the lens system can be only the inclination measuring light receiving lens 23b. The optical system can be simplified.

In the embodiments shown in FIGS. 17, 18 and 19, light having different wavelengths is used as the displacement measuring light and the inclination measuring light, and the dichroic mirror 1 is used for combining and separating them.
7 and 24 are used, linear polarizations having different polarization directions may be used as the displacement measurement light and the inclination measurement light, and the polarization beam splitters 38 and 39 may be used for combining and separating them.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical system in a conventional displacement sensor.

FIG. 2 is a diagram showing a configuration of an optical system of a displacement sensor according to an embodiment of the present invention.

FIG. 3 is a ray diagram for explaining the tilt measurement principle of the above.

FIG. 4 is a ray diagram for explaining the displacement measurement principle of the above.

FIG. 5 is an explanatory diagram for obtaining a movement amount of a light receiving spot of a light receiving element for displacement measurement when a detected object has displacement and inclination.

FIG. 6 is a block diagram showing an example of a signal processing circuit of the above displacement sensor.

FIG. 7 is a diagram illustrating dimensional effects of a light projecting lens and a light receiving lens in the above displacement sensor.

FIG. 8 is a diagram showing a configuration of an optical system of a displacement sensor according to another embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of an optical system of a displacement sensor which is another embodiment of the present invention and which uses displacement measuring light and inclination measuring light having different polarization directions.

FIG. 13 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 15 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

16A is a plan view showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention, and FIG. 16B is a diagram showing FIG.
2 is a cross-sectional view taken along line XX of FIG.

FIG. 17 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 18 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

FIG. 19 is a diagram showing a configuration of an optical system of a displacement sensor according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Detecting Object 15 Displacement Measuring Light 16 Tilt Measuring Light 17,24 Dichroic Mirror 18 Displacement Measuring Light Emitting Element 19 Tilt Measuring Light Emitting Element 20 Light Emitting Lens 21 Displacement Measuring Light Sensing Element 22 Tilt Measuring Light Sensing Element 23 Light Receiving Lens 31, 33, 35 Aperture stop 38, 39 Polarization beam splitter d Displacement amount of detected object β Inclination amount of detected object

Claims (16)

[Claims] 1. A displacement measuring optical system comprising a displacement measuring light source section for emitting displacement measuring light toward a detection area and a displacement measuring light receiving section for receiving the displacement measuring light reflected by the detection area. A displacement sensor comprising: an inclination measuring optical system for detecting the inclination of an object in a detection area. 2. The displacement according to claim 1, further comprising a correction unit that corrects output information of the displacement measuring optical system based on output information from the tilt measuring optical system. Sensor. 3. The tilt measuring optical system collimates the tilt measuring light projecting element that emits the tilt measuring light and the tilt measuring light that is emitted from the tilt measuring light projecting element and irradiates the detected object. A tilt measuring light projecting lens, a tilt measuring light receiving lens for collecting the tilt measuring light reflected by the detection object, and a tilt measuring light receiving element arranged at the focal position of the light receiving lens. And claim 1 or 2
The displacement sensor described in. 4. The tilt measuring optical system includes a tilt measuring light-projecting element that emits laser light, which is tilt measuring light, toward a detection object, and a tilt that refracts the tilt measuring light reflected by the detection object. The displacement sensor according to claim 1 or 2, which comprises a light receiving lens for measurement and a light receiving element for tilt measurement arranged at a focal position of the light receiving lens. 5. The displacement sensor according to claim 3, wherein the inclination measuring light receiving lens also serves as the light receiving lens of the displacement measuring light receiving section. 6. The displacement sensor according to claim 3, wherein the tilt measuring light projecting lens also serves as a light projecting lens of the displacement measuring light source section. 7. The displacement measuring light source section has a light projecting lens, the displacement measuring light receiving section has a light receiving lens, and the aperture diameter of the displacement measuring light receiving lens is equal to that of the displacement measuring light projecting lens. Characterized by having a size equal to or larger than the opening diameter,
The displacement sensor according to claim 1 or 2. 8. The light spot generated on the surface of the detection object by the displacement measuring light is inside the light spot generated on the surface of the detection object by the inclination measuring light, according to claim 1 or 2. Displacement sensor. 9. The displacement sensor according to claim 1, wherein the displacement measuring light and the tilt measuring light have different wavelengths from each other. 10. A displacement measuring light and a tilt measuring light having different wavelengths emitted from the light source side of the displacement measuring light source section and the tilt measuring optical system are overlapped by a photosynthesizer to irradiate the detected object. Displacement sensor according to claim 9, characterized in that 11. A displacement measuring light and a tilt measuring light, which have mutually different wavelengths and are overlapped with each other, are separated by a wavelength separator, and the displacement measuring light is guided to a displacement measuring light receiving section, and the tilt measuring light is tilt measuring optical. The displacement sensor according to claim 9 or 10, wherein the displacement sensor is guided to the light receiving side of the system. 12. The displacement sensor according to claim 1, wherein the displacement measuring light and the inclination measuring light are both polarized light, and the polarization directions thereof are different from each other. 13. The displacement measuring light and the inclination measuring light emitted from the light source side of the displacement measuring light source and the inclination measuring optical system and having different polarization directions are overlapped with each other by an optical combiner to irradiate the detected object. The displacement sensor according to claim 12, wherein: 14. The polarization measuring device separates the displacement measuring light and the tilt measuring light, which are different in polarization direction from each other, and guides the displacement measuring light to a displacement measuring light receiving section to tilt the tilt measuring light. The displacement sensor according to claim 12 or 13, characterized in that the displacement sensor is guided to the light receiving side of the measuring optical system. 15. The displacement sensor according to claim 3, wherein an aperture stop having a minute aperture is provided at a focal position on the incident side of the projection lens for tilt measurement. 16. The displacement sensor according to claim 3, wherein an aperture stop for limiting the beam size of the tilt measuring light is provided on the incident side of the tilt measuring light projecting lens.