JPH10148505A - Optical displacement gauge and method for measuring displacement using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress drop of the sensitivity even when the surface of an object is inclined. SOLUTION: The light of a light source is converted through a collimator lens 2 into a parallel light, and it passes through a beam splitter 3, and is separated into P and S polarization elements through a lens system consisting of focal lens 11 and objective lens 4, and they are converted on different positions on the light axis. The light reflecting on the surface of an object 5 passes through the lenses 4 and 11 and is reflected on the beam splitter 3, and then it is converted into a focusing light by a detection lens 6 and is separated into P and S polarization elements through a polarization beam splitter 7. Pin-holes 8a and 8b are arranged on an optical path of the light having polarization elements, that is, at the conjugate position for converging point of respective polarization elements through the objective lens 4. The respective polarization elements passing the pin-holes 8a and 8b are received by optical detectors 9a and 9b and are converted photoelectrically. Then they are computed by a differential amplifier 10, thus obtaining a differential output corresponding to the displacement of the surface of the object 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement meter and a displacement measuring method using the same.
The present invention relates to an optical displacement meter capable of suppressing a decrease in sensitivity even when the surface of an object is tilted, and a displacement measuring method using the same.

[0002]

2. Description of the Related Art As a conventional optical displacement meter, those described in, for example, US Pat. No. 3,788,341 and US Pat. No. 3,719,421 are known.

FIG. 8 is a configuration diagram showing the configuration of a conventional optical displacement meter 700. As shown in FIG. The measurement light flux of the parallel light passes through the beam splitter 3 and is condensed on the surface of the object 5 by the objective lens 4. The reflected light from the surface of the object 5 is
And is reflected by the beam splitter 7. The reflected light is
After being converted into convergent light by the lens 6, the light is incident on the beam splitter 7. In the beam splitter 7, the incident light is
Separate into luminous flux. One of the separated light beams is a pinhole 8
The light is received by the light receiving element 9a via a. The other is received by the light receiving element 9b via the pinhole 8b. The received light is photoelectrically converted by the light receiving elements 9a and 9b.

When the surface of the object 5 is perpendicular to the optical axis of the optical displacement meter 700, the beam spot at the positions of the pinholes 8a and 8b depends on the surface position of the object 5 as shown in FIG. To (c) (beam spots Ba to Bc).

The amount of light passing through the pinhole is shown in FIG.
(A) to (c). For this reason, the outputs of the light receiving elements 9a and 9b disposed behind the pinhole exhibit characteristics as shown in FIG. 10A due to the surface displacement of the object 5, and hence are shown in FIG. 10B. Such a differential output is obtained. The surface displacement of the object 5 is measured based on the differential output.

[0006]

In the above-described conventional optical displacement meter 700, when the surface of the object 5 is perpendicular to the optical axis of the optical displacement meter 700, a good output can be obtained. However, when the surface of the object 5 is inclined with respect to the optical axis of the optical displacement meter, the pinholes 8a, 8b
The beam spots at the positions of FIG.
It changes as shown in (c).

Normally, under the condition shown in FIG. 11C, the amount of light passing through the pinhole becomes maximum. However, since the focal point of the objective lens 4 and the position of the pinhole are not in a conjugate relationship, light is blocked by the aperture of the pinhole. As a result, the output of the light receiving element arranged behind the pinhole is
It changes as shown in FIG. Accordingly, the obtained differential output is as shown in FIG. 12 (b), which is significantly lower than when the surface of the object 5 is perpendicular to the optical axis (FIG. 10). As described above, when the surface of the object 5 is inclined, there is a problem that the sensitivity of the optical displacement meter 700 is significantly reduced.

In Japanese Patent Application Laid-Open No. 4-96514,
The P-polarized light component and the S-polarized light component are extracted from the linearly polarized light from the semiconductor laser light source, and are focused on the object surface with different focal positions by a birefringent optical system. A technique of receiving light by a light receiving element is disclosed. However, even in such an optical displacement meter, when the surface of the object is inclined, the same problem as described above may occur.

In addition to the above-mentioned conventional optical displacement meter, Y
.Fainman, E.Lenz, and, J.Shamir: Optical Profilomete
r; A New Method For High Sensitivity, Appl.Opt.21,17
The one disclosed in September (1982) 3200-3207 is known. In such a case, the same problem as described above may occur.

The present invention has been made in view of the above, and provides an optical displacement meter capable of suppressing a decrease in sensitivity even when the surface of an object is inclined, and a displacement measuring method using the same. The purpose is to:

[0011]

According to a first aspect of the present invention, there is provided an optical displacement meter which emits light for measuring the displacement of an object surface, such as a laser light source. And lens means for converting light emitted from the light source means into parallel light; and converting the light converted into parallel light by the lens means into different light-collecting positions for the P-polarized light component and the S-polarized light component on the object surface. Light condensing means for converging light in the vicinity, a P-polarized light component reflected from the object surface and
Separating means for separating the light of the polarized light component into the light of the P-polarized light component and the light of the S-polarized light component;
A first minute aperture unit disposed at a conjugate position with respect to the condensing position of the polarized light component, and a conjugate position with respect to the condensing position of the S-polarized component light collected by the condensing unit; , A first light receiving means for detecting the intensity of the P-polarized light component passing through the first minute opening means, and an S-polarized light passing through the second minute opening means. A second light receiving means for detecting the intensity of the component light; and a calculating means for obtaining a displacement of the object surface in the optical axis direction from the detected respective light intensities.

According to a second aspect of the present invention, there is provided an optical displacement meter which emits light for measuring the displacement of the surface of an object, such as a laser light source, and converts the light emitted from the light source into a parallel light. Lens means for converting the light into parallel light by the lens means, and condensing means for condensing the light converted into parallel light near the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component; Separating means for separating the P-polarized light component and the S-polarized light reflected by the light into the P-polarized light and the S-polarized light; and the condensing of the P-polarized light condensed by the condensing means. A light receiving surface which is arranged at a conjugate position with respect to the position and whose light receiving surface is concentrically divided to detect the intensity of the collected P-polarized component light;
And a conjugate position with respect to the condensing position of the S-polarized component light condensed by the condensing unit, and the light-receiving surface is divided concentrically, and the condensed S-polarized light A second light receiving means for detecting the intensity of the component light; and a calculating means for calculating a displacement of the object surface in the optical axis direction from the detected respective light intensities.

According to a third aspect of the present invention, there is provided an optical displacement meter which emits light for measuring the displacement of the surface of an object, such as a laser light source, and a polarization plane of the light which is arranged in a forward direction and a reverse direction. A Faraday rotator that rotates 45 ° around the same direction, a first half-wave plate that rotates the polarization plane of light by 45 ° in opposite directions in the forward and reverse directions, the Faraday rotator and the first Light condensing means for condensing light whose polarization plane has been rotated by 90 ° by a half-wave plate near the object surface with different light condensing positions for P-polarized light component and S-polarized light component; The Faraday rotator and the first half without reflecting and rotating the plane of polarization.
A first separating unit that separates the P-polarized component light and the S-polarized component light into light of the P-polarized component and light of the S-polarized component through a wavelength plate, and polarized light separated by the first separating unit. A second half-wave plate that rotates the polarization plane of the component light by 45 °, and separates the light whose polarization plane is rotated by the second half-wave plate into a P-polarized component and an S-polarized component. Separating means, and the condensed P-polarized light, which is disposed at a conjugate position with respect to the condensing position of the P-polarized light component condensed by the condensing means, and whose light-receiving surface is concentrically divided, A first light receiving unit that detects the intensity of the component light, and a light-collecting position of the S-polarized component light collected by the light collecting unit.
A second light-receiving surface which is arranged at a conjugate position and whose light-receiving surface is divided concentrically, and which detects the intensity of the condensed S-polarized light component;
And calculation means for calculating the displacement of the surface of the object in the optical axis direction from the detected light intensities.

According to a fourth aspect of the present invention, in the above-described optical displacement meter, the condensing means is a bifocal optical system utilizing birefringence of a material.

According to a fifth aspect of the present invention, there is provided an optical displacement meter which emits light for measuring a displacement of an object surface, and a lens which slightly converges or diverges the light emitted from the light source. Means, by separating the light converged or diverged by the lens means into light of a P-polarized component and light of an S-polarized component, the optical path of the light, a first optical path over the P-polarized component, Separation / light path splitting means for splitting the light into the second light path for the S-polarized light component, and mirror means for setting the light path length of the first light path longer than the light path length of the second light path in the first light path A first Faraday rotator that rotates the plane of polarization of light by 45 ° in the same direction in the forward and reverse directions, and a first Faraday rotator that rotates the plane of polarization of light by 45 ° in the opposite direction in the forward and reverse directions. 1/2 of
A second Faraday rotator for rotating the polarization plane of the light by 45 ° in the same direction in the forward and reverse directions, and the polarization plane of the light in the forward and reverse directions in the second optical path. Second half rotated 45 ° in the opposite direction in the direction
A wavelength plate, wherein the first Faraday rotator and the first half-wave plate rotate the polarization plane of the P-polarized component light by 90 °, The optical path is combined by combining the P-polarized component light obtained by rotating the polarization plane of the S-polarized component light by 90 ° with the Faraday rotator and the second half-wave plate into one light flux. ,
Or an optical path coupling for separating the light beam reflected on the object surface into the P-polarized light component and the S-polarized light component.
Separating means for separating the combined light beam from the first light path and the second light path;
A light path length difference from an optical path, and convergence or divergence by the lens means, and condensing means for condensing light near the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component, The first Faraday rotator and the first half in a first optical path
The S-polarized component light that has passed through the optical path coupling / separating means and the separating / optical path dividing means without rotating the polarization plane by the wavelength plate, and the second Faraday rotator and the second half-wave plate in the second optical path A separating unit that separates the P-polarized component light that has passed through the optical path coupling / separating unit and the separating / optical path splitting unit into the P-polarized component and the S-polarized component without rotating the polarization plane, and the focusing unit. With respect to the converging position of the condensed P-polarized component light, it is arranged at a conjugate position, and
A light-receiving surface divided concentrically, a first light-receiving means for detecting the intensity of the collected P-polarized light, and a light-collecting position of the S-polarized light collected by the light-collecting means; A second light receiving unit that is arranged at a conjugate position, and the light receiving surface is concentrically divided, and detects the intensity of the condensed S-polarized light, and the intensity of each of the detected light. Computing means for calculating the displacement of the object surface in the optical axis direction.

The optical displacement meter according to claim 6 is a light source means for measuring the displacement of the surface of the object, a lens means for converting light emitted from the light source means into parallel light,
By separating the light parallelized by the lens means into P-polarized light and S-polarized light, the optical path of the light is changed to a first optical path of the P-polarized light, and the S-polarized light. A first Faraday rotator for rotating the polarization plane of light in the first optical path by 45 ° in the same direction in the forward and reverse directions; And a first half-wave plate that rotates the polarization plane of the light beam by 45 ° in opposite directions in the forward and reverse directions, and in the second optical path, the polarization plane of the light is the same in the forward and reverse directions. A second Faraday rotator for rotating the light by 45 °, a second half-wave plate for rotating the polarization plane of the light by 45 ° in the forward and reverse directions, and a polarization plane in the second optical path. 90 ° rotated light,
Lens means for slightly converging or diverging,
The S-polarized light obtained by rotating the polarization plane of the P-polarized light by 90 ° by the first Faraday rotator and the first half-wave plate, and the second Faraday rotator and the second Faraday rotator. The light paths of the S-polarized light component are rotated by 90 ° by the half-wave plate of the above and the P-polarized light component obtained are combined into one light flux to combine the optical paths, or An optical path combining / separating means for separating the P-polarized light into the S-polarized light and the S-polarized light;
Condensing means for converging light near the object surface with different light condensing positions for polarized light components, the first Faraday rotator and the first half-wave plate reflected on the object surface and in a first optical path The light of the S-polarized component that has passed through the optical path coupling / separating means, the lens means, and the separating / optical path dividing means without rotating the polarization plane due to the second optical path
Optical path coupling / separation means and separation / separation means without rotating the plane of polarization by the Faraday rotator and the second half-wave plate
Separating means for separating the P-polarized light component having passed through the optical path splitting means into the P-polarized light component and the S-polarized light component; A first light receiving unit that is disposed at a conjugate position and has a light receiving surface divided concentrically and detects the intensity of the collected P-polarized light component; and an S-polarized light component collected by the light collecting unit. A second light receiving unit that is disposed at a conjugate position with respect to the light condensing position of the light, and the light receiving surface is concentrically divided, and detects the intensity of the collected S-polarized light component; Calculating means for calculating the displacement of the object surface in the optical axis direction from the detected intensities of the respective lights.

An optical displacement meter according to a seventh aspect of the present invention comprises a first light source means for emitting light of a first wavelength for measuring the displacement of the surface of the object, and a first light source means for measuring the displacement of the surface of the object. A second light source for emitting light of two wavelengths, a lens for slightly converging or diverging the light of the second wavelength, and the light of the first wavelength and the light of the second wavelength into one light flux A dichroic mirror that combines or separates the light into the light of the first wavelength and the light of the second wavelength, and a different condensing position where the combined light is converged or diverged by the lens unit. A light condensing means for converging light in the vicinity of the object surface with the light condensing means, and a light receiving surface arranged concentrically with respect to the light condensing position of the first wavelength light condensed by the light condensing means. Split and reflected on the object surface, A first light receiving means for detecting the intensity of the light of the first wavelength having passed through the dichroic mirror, and a light receiving means for disposing the light of the second wavelength condensed by the light condensing means at a conjugate position with respect to the light condensing position; A first light receiving means for detecting the intensity of light of a second wavelength reflected on the surface of the object and passing through the dichroic mirror and the lens means, the light receiving surface being divided concentrically; Computing means for calculating the displacement of the object surface in the optical axis direction from the intensity of the object.

The optical displacement meter according to the present invention has a first light source means for radiating light of a first wavelength for measuring the displacement of the object surface, and a second light source means for measuring the displacement of the object surface. A second light source for emitting light of two wavelengths, a lens for slightly converging or diverging the light of the second wavelength, and the light of the first wavelength and the light of the second wavelength into one light flux A dichroic mirror that combines or separates the light into the light of the first wavelength and the light of the second wavelength, and a different condensing position where the combined light is converged or diverged by the lens unit. Focusing means for focusing near the surface of the object with; a first micro-opening means disposed at a conjugate position with respect to the focusing position of the light of the first wavelength focused by the focusing means; Of the light of the second wavelength focused by the focusing means A second micro aperture means disposed at a conjugate position with respect to the light condensing position, a first light receiving means for detecting an intensity of light of a first wavelength having passed through the first micro aperture means, Second light receiving means for detecting the intensity of the light of the second wavelength passing through the second minute aperture means, and calculating means for calculating the displacement of the object surface in the optical axis direction from the detected respective light intensities; , Is provided.

According to a ninth aspect of the present invention, there is provided the optical displacement meter, wherein the light condensing means sets the radiation angle of the light radiated from each light source to a different position. It was done.

Further, the optical displacement meter according to claim 10 is:
In the above optical displacement meter, the light condensing means is a lens means having chromatic aberration.

The displacement measuring method according to claim 11 is
Converting the light for measuring the displacement of the object surface into parallel light, condensing this parallel light near the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component, P-polarized light component reflected from the object surface and S
Separating the light of the polarized light component into the light of the P-polarized light component and the light of the S-polarized light component; and conjugate the light of the P-polarized light component to the light collecting position of the collected P-polarized light component. Receiving the light by passing through a first minute aperture located at a position; and connecting the S-polarized component light to a second position located at a conjugate position with respect to the focused position of the focused S-polarized component light. And a step of obtaining the displacement of the object surface in the optical axis direction from the intensity of each of the received lights.

Further, according to the displacement measuring method of the present invention,
Converting the light for measuring the displacement of the object surface into parallel light, condensing this parallel light near the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component, P-polarized light component reflected from the object surface and S
Separating the light of the polarized light component into the light of the P-polarized light component and the light of the S-polarized light component; and conjugate the light of the P-polarized light component to the light collecting position of the collected P-polarized light component. Receiving light at a concentrically divided light receiving surface located at the position,
Receiving the S-polarized component light on a concentrically divided light-receiving surface located at a conjugate position with respect to the condensed position of the collected S-polarized component light; Determining the displacement of the object surface in the optical axis direction from the intensity of the object.

The displacement measuring method according to claim 13 is
Converting the light into parallel light to measure the displacement of the object surface, rotating the polarization plane of the parallel light by 90 ° in one direction by a Faraday rotator and a first half-wave plate, Condensing the light whose polarization plane has been rotated by 90 ° by the Faraday rotator and the first half-wave plate into the vicinity of the surface of the object at different condensing positions for the P-polarized light component and the S-polarized light component; Transmitting the P-polarized light component and the S-polarized light component reflected by the object surface through the Faraday rotator and the first half-wave plate without rotating the polarization plane as a result; and Separating the passed P-polarized light component and S-polarized light component into the P-polarized light component and the S-polarized light component;
The polarization plane of the polarized light component separated by the two-wavelength plate is set to 4
Rotating the light by 5 degrees, separating the light whose polarization plane has been rotated by the second half-wave plate into a P-polarized light component and an S-polarized light component, A step of receiving a concentrically divided light receiving surface located at a conjugate position with respect to the light condensing position of the light of the emitted P-polarized component;
Receiving the S-polarized component light on a concentrically divided light-receiving surface located at a conjugate position with respect to the condensed position of the collected S-polarized component light; Determining the displacement of the object surface in the optical axis direction from the intensity of the object.

Further, the displacement measuring method according to claim 14 is
A step of slightly converging or diverging light for measuring the displacement of the surface of the object, a step of applying the converged or divergent light to a first optical path over P-polarized components having different optical path lengths, and the S-polarized component. And a step of dividing the polarization plane of the P-polarized component light in one direction by a first Faraday rotator and a first half-wave plate in the first optical path. Rotating the light into S-polarized component light; and, in the second optical path, the polarization plane of the S-polarized component light is rotated by 90 ° in one direction by a second Faraday rotator and a second half-wave plate. Rotating the light into P-polarized light, combining the S-polarized light from the first optical path and the P-polarized light from the second optical path into one light flux, The luminous flux that has passed through the first optical path and the second optical path. Path length difference, the convergence or divergence of the light, by the action of condensing near the surface of the object with a different condensing position of the P-polarized component and S-polarized component, and reflected on the surface of the object Separating the light beam into the P-polarized light component and the S-polarized light component; and in the first optical path, the P-polarized light component and the S-polarized light reflected on the object surface are polarized. The first Faraday rotation element and the first 1
Passing through a half-wave plate and the second optical path,
Passing the P-polarized light component and the S-polarized light component reflected by the object surface through the second Faraday rotation element and the second half-wave plate without rotating the polarization plane as a result. Combining the S-polarized component light returned from the first optical path and the P-polarized component light returned from the second optical path into one light flux again, and combining the first and second optical paths; ,
Separating the combined light beam into a P-polarized light component and an S-polarized light component; and converting the P-polarized light component to a conjugate position with respect to the condensing position of the collected P-polarized light component. Receiving light at a concentrically divided light receiving surface located at
Receiving the S-polarized component light on a concentrically divided light-receiving surface located at a conjugate position with respect to the condensed position of the collected S-polarized component light; Determining the displacement of the object surface in the optical axis direction from the intensity of the object.

The displacement measuring method according to claim 15 is
Converting the light for measuring the displacement of the surface of the object into parallel light, converting the parallel light into a first optical path involving a P-polarized component having substantially the same optical path length, and a second optical path involving the S-polarized component And dividing the first optical path into the first optical path.
Rotating the polarization plane of the light of the P-polarized component by 90 ° in one direction by the Faraday rotator and the first half-wave plate to generate light of the S-polarized component; and further, in the first optical path, A step of slightly converging or diverging the light rotated by 90 °;
Rotating the polarization plane of the S-polarized light component by 90 ° in one direction by the Faraday rotator and the second half-wave plate to obtain the P-polarized light component;
Combining the light of the polarized light component and the light of the P-polarized light component from the second light path into one light flux and combining the first light path and the second light path; Converging the P-polarized light component and the S-polarized light component in the vicinity of the surface of the object with different light-condensing positions by the action of divergence; And in the first optical path, the light of the P-polarized component and the S-polarized component reflected on the object surface does not rotate the plane of polarization as a result, and the first Faraday rotation Element and first half
Passing through a wave plate, and in the second optical path, the light of the P-polarized component and the S-polarized component reflected on the object surface does not rotate the polarization plane as a result, and the second Faraday rotation element And passing through a second half-wave plate, combining the S-polarized component light returned from the first optical path and the P-polarized component light returned from the second optical path into one light flux again. And separating the combined light beam into P-polarized light and S-polarized light; and transferring the P-polarized light to the converging position of the collected P-polarized light. Receiving light at a concentrically divided light receiving surface located at a conjugate position with respect to the light, and positioning the S-polarized component light at a conjugate position with respect to the focused position of the collected S-polarized component light. Receiving light on a concentrically divided light receiving surface,
Obtaining the displacement of the surface of the object in the optical axis direction from the intensity of each of the received lights.

[0026] The displacement measuring method according to claim 16 is characterized in that:
Emitting a first wavelength of light for measuring the displacement of the object surface; emitting a second wavelength of light for measuring the displacement of the object surface; and slightly converging the second wavelength of light. Or diverging the light of the first wavelength and the second light.
Combining the light having the wavelength into one light flux, and condensing the combined light in the vicinity of the surface of the object at different light condensing positions by the convergence or divergence of the light of the second displacement meter. Separating the light flux reflected by the object surface into the first wavelength light and the second wavelength light; and converting the first wavelength light to the collected first wavelength light. A step of receiving light at a concentrically divided light receiving surface located at a conjugate position with respect to the light condensing position, and applying the light of the second wavelength to the light condensing position of the collected light of the second wavelength. The method includes a step of receiving light on a concentrically divided light receiving surface located at a conjugate position, and a step of calculating a displacement of the object surface in the optical axis direction from the intensity of each of the received light.

[0027] The displacement measuring method according to claim 17 is characterized in that:
Emitting a first wavelength of light for measuring the displacement of the object surface; emitting a second wavelength of light for measuring the displacement of the object surface; and slightly converging the second wavelength of light. Or diverging the light of the first wavelength and the second light.
Combining the light having the wavelength into one light flux, and condensing the combined light in the vicinity of the surface of the object at different light condensing positions by the convergence or divergence of the light of the second displacement meter. Separating the light flux reflected by the object surface into the first wavelength light and the second wavelength light; and converting the first wavelength light to the collected first wavelength light. Receiving the light by passing through a first micro aperture located at a conjugate position with respect to the light condensing position; and applying the light of the second wavelength to the light condensing position of the collected light of the second wavelength. The method includes a step of receiving the light by passing through the second minute aperture located at the conjugate position, and a step of calculating a displacement of the object surface in the optical axis direction from the intensity of the received light.

[0028] Further, the displacement measuring method according to claim 18 is characterized in that:
In the above displacement measurement method, the step of converging light near the surface of the object with different light condensing positions at the first wavelength and the second wavelength is performed using lens means having chromatic aberration.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical displacement meter according to the present invention and a displacement measuring method using the same will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

(Embodiment 1) FIG. 1 is a configuration diagram showing a configuration of an optical displacement meter 100 according to Embodiment 1 of the present invention. Light emitted from a light source 1 such as a semiconductor laser is converted into parallel light by a collimator lens 2. The parallel light passes through a beam splitter 3 and passes through a bifocal lens 1.
1 and is focused on the surface of the object 5 by the objective lens 4. The bifocal lens 11 refers to a lens having a different focal length for orthogonally polarized light. This bifocal lens 1
By the function of 1, the light of the P-polarized light component and the light of the S-polarized light component can be condensed at different positions on the optical axis.

Next, the light reflected on the surface of the object 5 is reflected by the beam splitter 3 via the objective lens 4 and the focusing lens 11. The reflected light is converted into convergent light by the detection lens 6 and then converted by the polarization beam splitter 7 into P light.
The light is separated into a polarized light component and an S-polarized light component. On the optical path of the P-polarized component light, a pinhole 8a is arranged at a conjugate position with the condensing point of the P-polarized component by the objective lens 4.

The light of the P-polarized component is photoelectrically converted by a photodetector 9a disposed behind the pinhole 8a.
Similarly, on the optical path of the S-polarized light component, a pinhole 8b is provided at a position conjugate with the focal point of the S-polarized light component by the objective lens 4.
Is arranged. The light of the S-polarized component is photoelectrically converted by the photodetector 9b disposed behind the pinhole 8b. Here, the setting of the conjugate position is performed by mechanically positioning the interval between the detection lens 6 and the photodetector 9 with reference to the focal point of the objective lens 4.

The photoelectrically converted signal is guided to the differential amplifier 10 and performs a calculation represented by the equation (1) to obtain a differential output S according to the displacement of the surface of the object 5. That is, the calculation of S = (9a-9b) / (9a + 9b) (1) is performed.

As described above, according to the optical displacement meter 100,
Since the pinholes 8a and 8b are arranged at conjugate positions with the converging point of each polarized light component by the objective lens 4, there is almost no light blocking by the pinholes. For this reason, a decrease in the sensitivity of the differential output can be effectively suppressed.

(Embodiment 2) FIG. 2 is a configuration diagram showing a configuration of an optical displacement meter 200 according to Embodiment 2 of the present invention. This optical displacement meter 200 has substantially the same configuration as that of the first embodiment, but instead of the pinholes 8a and 8b and the photodetectors 9a and 9b in the first embodiment,
The difference is that the photodetectors 12a and 12b are arranged at conjugate positions. As shown in FIGS. 3A and 3B, the light detectors 12a and 12b have their light receiving surfaces divided concentrically.

Light emitted from a light source 1 such as a semiconductor laser is converted by a collimator lens 2 into parallel light.
The parallel light enters the bifocal lens 11 via the beam splitter 3 and is condensed on the surface of the object 5 by the objective lens 4. By the function of the bifocal lens 11, the light of the P-polarized light component and the light of the S-polarized light component can be collected at different positions on the optical axis.

Next, the light reflected on the surface of the object 5 is reflected by the beam splitter 3 via the objective lens 4 and the focusing lens 11. The reflected light is converted into convergent light by the detection lens 6 and then converted by the polarization beam splitter 7 into P light.
The light is split into a polarized light component and an S-polarized light component. A photodetector 12a is disposed on the optical path of the P-polarized component light and at a position conjugate with the converging point of the P-polarized component by the objective lens 4. The light of the P polarization component is photoelectrically converted by the photodetector 12a.

Similarly, a photodetector 12b is disposed on the optical path of the S-polarized light component and at a conjugate position with the condensing point of the S-polarized light component by the objective lens 4. The S-polarized light component is photoelectrically converted by the photodetector 12b. Here, the conjugate position is determined by mechanically positioning an interval between the detection lens 6 and the photodetector 12 with reference to the condensing point of the objective lens 4.

The photoelectrically converted signal is guided to the differential amplifier 10 and performs a calculation represented by the equation (2) to obtain a differential output S corresponding to the displacement of the surface of the object 5. S = (12a [in] + 12b [out] −12a [out] −12b [in]) / (12a [in] + 12b [out] + 12a [out] + 12b [in]) (2)

As described above, according to the optical displacement meter 200,
Since the photodetectors 12a and 12b are used, light is less likely to be blocked than when pinholes are used. Therefore, as compared with the optical displacement meter 100 of the first embodiment, the light use efficiency is higher, and the S / N ratio is improved.

(Embodiment 3) FIG. 4 is a configuration diagram showing a configuration of an optical displacement meter 300 according to Embodiment 3 of the present invention. This optical displacement meter 300 uses a polarization beam splitter 13 instead of the beam splitter 3 used in the optical displacement meter 200 of the second embodiment, and further includes a Faraday rotator 14, a half-wave plate 15, 16 is added. Other configurations are the same as those used for the optical displacement meter 200 of the second embodiment.

The light of the P-polarized component emitted from the light source 1 such as a semiconductor laser is converted by the collimator lens 2 into parallel light. The P-polarized light converted into parallel light passes through the polarization beam splitter 13. Then, the polarization plane is rotated right 45 ° by the Faraday rotator 14,
Subsequently, the polarization plane is further moved to the right 45
° to be S-polarized light. Next, light having a P-polarized light component and an S-polarized light component is converted into light having a P-polarized light component and an S-polarized light component by the bifocal lens 11, and the light of the P-polarized light component and the polarized light component is shifted to different positions on the optical axis by the bifocal lens and the objective lens 4. Collect light.

The light reflected on the surface of the object 5 passes through the objective lens 4 and the bifocal lens 11. The light of the S-polarized light component is first rotated by 45 ° to the right in the polarization plane by the half-wave plate 15, and subsequently rotated in the polarization plane by 45 ° to the left by the Faraday rotator 14 and returned to its original state. The light reaches the polarization beam splitter 13 with the S-polarized light component. Similarly, the half-wave plate 15 and the Faraday rotator 1
4, the polarization beam splitter 13 remains as the P-polarized component.
To reach.

The S-polarized light is reflected by the polarization beam splitter 13. The light of the P polarization component passes through the polarization beam splitter 13. The reflected light of the S-polarized light component is rotated by 45 ° in the polarization plane by the half-wave plate 16, and becomes light having the P-polarized light component and the polarized light component again.
This light enters the polarization beam splitter 7 and is split into P-polarized light and S-polarized light.

A photodetector 12a is arranged on the optical path of the light of the P-polarized component and at a position conjugate with the converging point of the P-polarized component by the objective lens 4. The light of the P polarization component is photoelectrically converted by the photodetector 12a. Similarly, a photodetector 12b is disposed on the optical path of the S-polarized component light and at a conjugate position with the focal point of the S-polarized component by the objective lens 4. The S-polarized light component is photoelectrically converted by the photodetector 12b. Here, the conjugate position is determined by mechanically positioning an interval between the detection lens 6 and the photodetector 12 with reference to the condensing point of the objective lens 4.

The photoelectrically converted signal is guided to the differential amplifier 10 and is subjected to the operation represented by the equation (2) (see Embodiment 2) to obtain a differential signal corresponding to the displacement of the surface of the object 5. Obtain the output S.

According to the optical displacement meter 300, the optical system of the optical displacement meter 300 functions as an isolator,
At the same time as the light use efficiency is improved, the return light to the light source is reduced. For this reason, output fluctuations caused by return light can be suppressed. Also, instead of the photodetectors 12a and 12b, the pinhole 8 used in the optical displacement meter 100 of the first embodiment is used.
The same effects as described above can be obtained by using the photodetectors a and 8b and the photodetectors 9a and 9b.

(Embodiment 4) FIG. 5 is a configuration diagram showing a configuration of an optical displacement meter 400 according to Embodiment 4 of the present invention. The optical displacement meter 400 is characterized in that a difference is provided between the optical path length of P-polarized light and the optical path length of S-polarized light so that each polarized light component is condensed at a different position on the optical axis. . Therefore, the bifocal lens 11 is not used. Other configurations are substantially the same as those of the optical displacement meter 300 of the third embodiment. The difference in the optical path length is determined by using one of the polarized light components as an optical path to mirror 1
It is set by making it longer using 8,19.

The light emitted from the light source 101 is
02 is converted into a light beam that slightly diverges or converges. Due to the divergence or convergence and the difference in the optical path length, the light of each polarization component can be collected at different positions on the optical axis. Next, the luminous flux is converted by the polarizing beam splitter 17 into P
The light is split into a polarized light component and a s-polarized light component, and is split into a first optical path and a second optical path.

First, in the first optical path, the S-polarized light reflected by the polarizing beam splitter 17 is converted into P-polarized light by the Faraday rotator 14a and the half-wave plate 15a through the mirror 18 on the outward path. Is done. The converted light of the P polarization component is reflected by the mirror 19 and is reflected by the polarization beam splitter 20.

On the other hand, in the second optical path, the P-polarized light transmitted through the polarizing beam splitter 17 is converted to the S-polarized light by the Faraday rotator 14b and the half-wave plate 15b on the outward path. . This converted S
The light of the polarization component passes through the polarization beam splitter 20.

Next, the P-polarized light from the first optical path and the S-polarized light from the second optical path are combined by the polarization beam splitter 20, and the first optical path and the second optical path are combined again. Is done. The combined light flux is collected near the surface of the object 5. Here, due to the divergence or convergence by the lens 102 and the difference in the optical path length between the first optical path and the second optical path, the light of each polarization component is condensed at different positions near the surface of the object 5. Next, the light beam reflected on the surface of the object 5 is again separated by the polarizing beam splitter 20 into P-polarized light and S-polarized light.

On the return path in the first optical path, the object 5
Is reflected by the polarization beam splitter 20 again, and passes through the mirror 19, the Faraday rotator 14a, and the half-wave plate 15a. Then, after passing through the mirror 18, as described above, the light of the P-polarized component reaches the polarization beam splitter 17 and passes through the polarization beam splitter 17.

On the other hand, on the return path in the second optical path, the object 5
The light of the S-polarized component reflected by the surface passes through the polarizing beam splitter 20 again and passes through the Faraday rotator 14b and the half-wave plate 15b. Then, as described above, the light of the S-polarized component reaches the polarization beam splitter 17 and is reflected by the polarization beam splitter 17.

In the polarization beam splitter 17, the P-polarized light and the S-polarized light are combined again. The combined light flux is converted into convergent light by the detection lens 6 and then reaches the polarization beam splitter 7. The convergent light is split again by the polarization beam splitter 7 into P-polarized light and S-polarized light. A photodetector 12a is disposed on the optical path of the P-polarized component light and at a position conjugate with the converging point of the P-polarized component by the objective lens 4.

The P-polarized light is photoelectrically converted by the photodetector 12a. Similarly, a photodetector 12b is disposed on the optical path of the S-polarized component light and at a conjugate position with the focal point of the S-polarized component by the objective lens 4. The S-polarized light component is photoelectrically converted by the photodetector 12b. Here, the conjugate position is determined by mechanically positioning an interval between the detection lens 6 and the photodetector 12 with reference to the condensing point of the objective lens 4.

The photoelectrically converted signal is guided to the differential amplifier 10 and is subjected to an operation represented by the equation (2) (see Embodiment 2) to obtain a differential signal corresponding to the displacement of the surface of the object 5. Obtain the output S.

According to the optical displacement meter 400, convergence or divergence by the lens 102, and the first optical path and the second optical path
The focusing positions of the P-polarized component light and the S-polarized component light can be set by the optical path length difference from the optical path. For this reason, the degree of freedom in setting the focusing position can be increased.

(Embodiment 5) FIG. 6 is a configuration diagram showing a configuration of an optical displacement meter 500 according to Embodiment 5 of the present invention. This optical displacement meter 500 is substantially the same as the optical displacement meter 400 of the fourth embodiment, except that a parallel light beam is made incident on a polarizing beam splitter, and further, the light condensing position of each polarization component is adjusted by a lens 21. There is a feature in the setting.
The optical path lengths of the first optical path and the second optical path are the same.

The light emitted from the light source 1 is converted by the collimator lens 2 into parallel light. The parallel light is split by the polarizing beam splitter 17 into P-polarized light and S-polarized light, and is split into a first optical path and a second optical path.

First, in the first optical path, the P-polarized light transmitted through the polarization beam splitter 17 is converted to the S-polarized light by the Faraday rotator 14a and the half-wave plate 15a on the outward path. . This converted S
The light of the polarization component is reflected by the mirror 19 and slightly converged or diverged by the lens 21. Subsequently, the S
The polarized light component is reflected by the polarization beam splitter 20.

On the other hand, in the second optical path, the S-polarized light reflected by the polarization beam splitter 17 passes through the mirror 18 on the outward path and is converted into the P-polarized light by the Faraday rotator 14b and the half-wave plate 15b. Is done. The converted P-polarized light component is transmitted through the polarization beam splitter 20.

Next, the P-polarized light component from the first optical path and the S-polarized light component from the second optical path are combined again by the polarization beam splitter 20, and the first optical path and the second optical path are again combined. Be combined. The combined light flux is collected near the surface of the object 5. Here, due to the divergence or convergence by the lens 21, the light of each polarization component is condensed at different positions near the surface of the object 5. Next, the light beam reflected on the surface of the object 5 is reflected by the polarizing beam splitter 20.
Then, the light is again separated into the P-polarized light and the S-polarized light.

On the return path in the first optical path, the object 5
Is reflected by the polarizing beam splitter 20 again, and passes through the lens 21, the Faraday rotator 14b, and the half-wave plate 15b. Then, as described above, the light of the S-polarized component reaches the polarization beam splitter 17 and is reflected by the polarization beam splitter 17.

On the other hand, on the return path in the second optical path, the object 5
The light of the P-polarized light component reflected on the surface of the light source passes through the polarization beam splitter 20 again, and passes through the Faraday rotator 14a and the half-wave plate 15a. After passing through the mirror 18, as described above, the light of the P-polarized component arrives at the polarization beam splitter 17 and passes through the polarization beam splitter 17.

The polarization beam splitter 17 combines the P-polarized light component and the S-polarized light component again. The combined light flux is converted into convergent light by the detection lens 6 and then reaches the polarization beam splitter 7. The convergent light is split again by the polarization beam splitter 7 into P-polarized light and S-polarized light. A photodetector 12a is disposed on the optical path of the P-polarized component light and at a position conjugate with the converging point of the P-polarized component by the objective lens 4.

The P-polarized light is photoelectrically converted by the photodetector 12a. Similarly, a photodetector 12b is disposed on the optical path of the S-polarized component light and at a conjugate position with the focal point of the S-polarized component by the objective lens 4. The S-polarized light component is photoelectrically converted by the photodetector 12b. Here, the conjugate position is determined by mechanically positioning an interval between the detection lens 6 and the photodetector 12 with reference to the condensing point of the objective lens 4.

The photoelectrically converted signal is guided to a differential amplifier 10 and is subjected to an operation represented by the equation (2) (see Embodiment 2) to obtain a differential signal corresponding to the displacement of the surface of the object 5. Obtain the output S.

According to the optical displacement meter 500, the focusing position of the P-polarized light component (or the S-polarized light component) can be easily set by the lens 21. For this reason, the degree of freedom in setting the focusing position can be increased.

(Embodiment 6) FIG. 7 is a configuration diagram showing a configuration of an optical displacement meter 600 according to Embodiment 6 of the present invention. The optical displacement meter 600 is characterized in that the light condensing positions are made different using light of different wavelengths.

First, the light emitted from the light source 1a that emits light of the wavelength λ1 passes through the beam splitter 3a and the dichroic mirror 22, and is condensed on the surface of the object 5 by the objective lens 4. The light reflected from the surface of the object 5 passes through the dichroic mirror 22 again and is reflected by the beam splitter 3a. This reflected light is condensed by the detection lens 6a and reaches the photodetector 12a arranged at a position conjugate with the condensing point of the objective lens 4.

On the other hand, the light emitted from the light source 1 b that emits light of the wavelength λ 2 passes through the beam splitter 3 b and is reflected by the mirror 19. Subsequently, the light is reflected by the dichroic mirror 22 via the lens 21 and is condensed on the surface of the object 5 by the objective lens 4.

Here, the light having the wavelength λ1 and the light having the wavelength λ2 are condensed at different positions on the optical axis by the function of the lens 21. The reflected light reflected on the surface of the object 5 is
The light is reflected again by the dichroic mirror 22 and is reflected by the beam splitter 3b. The reflected light is condensed by the detection lens 6b and reaches the photodetector 12b arranged at a position conjugate with the condensing point of the objective lens 4.

Now, the wavelength λ1 reaching the photodetector 12a
Is photoelectrically converted by the photodetector 12a. Similarly, the light having the wavelength λ2 that has reached the photodetector 12b is photoelectrically converted by the photodetector 12b. Here, the conjugate position is determined by mechanically positioning an interval between the detection lens 6 and the photodetector 12 with reference to the condensing point of the objective lens 4.

The photoelectrically converted signal is guided to a differential amplifier 10 and is subjected to an operation represented by the equation (2) (see Embodiment 2) to obtain a differential signal corresponding to the displacement of the surface of the object 5. Obtain the output S.

As described above, according to the optical displacement meter 600,
By using light of different wavelengths and further providing a lens 21 for diverging or converging the light on the optical path, the focusing position can be easily set.

Instead of using the lens 21, it is also possible to use the objective lens 4 having chromatic aberration to focus the light of each wavelength at different positions on the optical axis. This simplifies the configuration of the optical system.

[0078]

As described above, the optical displacement meter (claim 1) and the displacement measuring method (claim 11) of the present invention.
According to the method, the light of the P-polarized light component and the light of the S-polarized light component are respectively condensed at different positions on the optical axis, and the minute aperture means is arranged at a conjugate position with the light condensing position. As we detect the light of each polarized component that has passed,
Even when the surface of the object is inclined, a decrease in the sensitivity of the differential output can be minimized.

According to the optical displacement meter (claim 2) and the displacement measuring method (claim 12) of the present invention, instead of the micro aperture means, a light receiving element having a light receiving surface divided concentrically is used. Since it is used, the light utilization efficiency is increased, and the S / N ratio of the differential output can be improved.

Next, according to the optical displacement meter (claim 3) and the displacement measuring method (claim 13) of the present invention, the return light to the light source can be reduced, so that the output fluctuation due to the return light can be suppressed. Further, the light use efficiency is improved, and the S / N ratio of the differential output can be improved.

Next, according to the optical displacement meter of the present invention (claim 4), since the bifocal lens is used for the objective lens system, the optical system can be simplified and downsized.

Next, according to the optical displacement meter (claim 5) and the displacement measuring method (claim 14) of the present invention, divergent light or convergent light is used, and furthermore, the optical path of the light of each polarization component is added to the optical path. By providing the difference, it is possible to easily set the focusing position of the light of each polarization component.

Next, according to the optical displacement meter (claim 6) and the displacement measuring method (claim 15) of the present invention, the light of each polarization component is respectively converted by using the divergent light or the convergent light by the lens means. Since light is condensed at different positions, the light condensing position of each polarized light component can be easily set.

Next, according to the optical displacement meter (claim 7) and the displacement measuring method (claim 16) of the present invention, lights having different wavelengths are condensed at different positions on the optical axis, respectively. Since the light receiving element whose light receiving surface is concentrically divided is disposed at a conjugate position with respect to the light condensing point, even if the surface of the object is inclined, a decrease in the sensitivity of the differential output can be suppressed to a minimum. Further, the light use efficiency is increased, and the S / N ratio of the differential output can be improved.

According to the optical displacement meter (claim 8) and the displacement measuring method (claim 17) of the present invention, lights having different wavelengths are condensed at different positions on the optical axis, respectively. The micro aperture means is arranged at a conjugate position with respect to the light condensing point, and the light of each polarized light component passing through the micro aperture means is detected. Therefore, even when the surface of the object is inclined, the differential output is obtained. Can be suppressed to a minimum.

Next, according to the optical displacement meter of the present invention (claim 9), the emission angle of the light emitted from each light source can be set at a different position by the optical means. The light condensing position of the wavelength can be easily set.

Next, according to the optical displacement meter (claim 10) and the displacement measuring method (claim 18) of the present invention, light of each wavelength is condensed at different positions on the optical axis by utilizing chromatic aberration. Therefore, there is no need to use a complicated optical system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 2 of the present invention.

FIG. 3 is an explanatory diagram illustrating a state of a light receiving surface of the photodetector illustrated in FIG. 2;

FIG. 4 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 4 of the present invention.

FIG. 6 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 5 of the present invention.

FIG. 7 is a configuration diagram showing a configuration of an optical displacement meter according to Embodiment 6 of the present invention.

FIG. 8 is a configuration diagram showing a configuration of a conventional optical displacement meter.

9 is an explanatory diagram for explaining a state of a beam spot at a pinhole position when an object surface is perpendicular to an optical axis of the optical displacement meter of FIG.

10 is a graph showing the relationship between the output of the light receiving element shown in FIG. 8 and the differential output obtained from this output with respect to the displacement of the object surface in the case of FIG. 9;

FIG. 11 is an explanatory diagram for explaining a state of a beam spot at a pinhole position when an object surface is inclined with respect to an optical axis of the optical displacement meter of FIG. 8;

12 is a graph showing the relationship between the output of the light receiving element shown in FIG. 8 and the differential output obtained from this output with respect to the displacement of the object surface in the case of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 optical displacement meter 1 light source 2 collimator lens 3 beam splitter 4 objective lens 5 object 6 detection lens 7 polarization beam splitter 8 pinhole 9 photodetector 10 differential amplifier 11 bifocal lens

Claims (18)

[Claims] 1. A light source means, such as a laser light source, for emitting light for measuring displacement of an object surface, a lens means for converting light emitted from the light source means into parallel light, A light condensing means for condensing the light converted into parallel light near the object surface with different light condensing positions for the p-polarized light component and the s-polarized light component; Separating means for separating the light into the P-polarized component light and the S-polarized component light; and a separating means disposed at a conjugate position with respect to the condensing position of the P-polarized component light condensed by the condensing means. 1 micro aperture means, 2nd micro aperture means arranged at a conjugate position with respect to the condensing position of the S-polarized component light condensed by the condensing means, and 1st micro aperture means Check the intensity of the transmitted P-polarized light First light receiving means for emitting light; second light receiving means for detecting the intensity of S-polarized component light having passed through the second minute aperture means; and optical axis direction from the detected light intensities. And a calculating means for calculating a displacement of the surface of the object in the above. 2. A light source means, such as a laser light source, for emitting light for measuring the displacement of the surface of an object, a lens means for converting light emitted from the light source means into parallel light, A light condensing means for condensing the light converted into parallel light near the object surface with different light condensing positions for the p-polarized light component and the s-polarized light component; Separation means for separating the light into the P-polarized light and the S-polarized light; and a conjugate position with respect to the light-collected position of the P-polarized light collected by the light-collecting means. A first light receiving unit for detecting the intensity of the condensed P-polarized light component, wherein the light receiving surface is concentrically divided; and a light condensing position of the S-polarized light component condensed by the light condensing unit. Is located at a conjugate position with respect to A light-receiving surface is divided concentrically, a second light-receiving means for detecting the intensity of the collected S-polarized light, and the detected intensity of each of the light, An optical displacement meter comprising: a calculating means for determining a displacement; 3. A light source means, such as a laser light source, for emitting light for measuring the displacement of the surface of an object, and the polarization plane of the light is rotated by 45 ° in the same direction in the forward and reverse directions.
Faraday rotator to rotate, and the polarization plane of light 45 ° in opposite directions in the forward and reverse directions
A first half-wave plate to be rotated, and a light whose polarization plane is rotated by 90 ° by the Faraday rotator and the first half-wave plate to a P-polarized component and S
Light-collecting means for condensing light near the object surface with different light-condensing positions for polarization components; the Faraday rotator and the first half-wave plate reflected on the object surface without rotating the plane of polarization Through the P
A first separating unit that separates the polarized component light and the s-polarized component light into the p-polarized component light and the s-polarized component light, and a polarization plane of the polarized component light separated by the first separating unit. A second half-wave plate rotated by 45 °, separation means for separating light whose polarization plane has been rotated by the second half-wave plate into a P-polarized component and an S-polarized component; With respect to the condensing position of the light of the P-polarized light component condensed by the optical means, the light-receiving surface is arranged concentrically with respect to the converging position, and the intensity of the light of the condensed P-polarized light component is detected A first light receiving unit, which is disposed at a conjugate position with respect to the condensing position of the S-polarized light component condensed by the condensing unit, and wherein the light receiving surface is concentrically divided, A second light receiving means for detecting the intensity of the S-polarized component light, Calculating means for calculating the displacement of the surface of the object in the direction of the optical axis from the light intensity of the light. 4. The optical displacement meter according to claim 1, wherein said focusing means is a bifocal optical system utilizing birefringence of a material. 5. Light source means for emitting light for measuring the displacement of the surface of an object, lens means for slightly converging or diverging light emitted from the light source means, and converging or diverging by the lens means. By separating the obtained light into light of a P-polarized component and light of an S-polarized component, the optical path of the light is changed to a first optical path related to the P-polarized component,
Separation / optical path splitting means for splitting into a second optical path for a polarization component; and mirror means for setting the optical path length of the first optical path longer than the optical path length of the second optical path in the first optical path; 45 ° of the plane of polarization of the light in the same direction in the forward and reverse directions
A first Faraday rotator to rotate, and a polarization plane of light by 45 ° in opposite directions in the forward and reverse directions
A first half-wave plate to be rotated; and wherein in the second optical path, the polarization plane of light is rotated by 45 ° in the same direction in the forward and reverse directions.
A second Faraday rotator to rotate, and a polarization plane of light by 45 ° in opposite directions in the forward and reverse directions
And a second half-wave plate to be rotated. S-polarized light obtained by rotating the polarization plane of the P-polarized component by 90 ° by the first Faraday rotation element and the first half-wave plate Component light and P-polarized component light obtained by rotating the polarization plane of S-polarized component light by 90 ° by the second Faraday rotator and the second half-wave plate into one light flux An optical path combining / separating unit that combines the optical paths by combining, or separates the light flux reflected on the object surface into the P-polarized component light and the S-polarized component light, By the action of the optical path length difference between the first optical path and the second optical path and the convergence or divergence of the lens means, light is condensed near the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component. Light condensing means for reflecting light on the object surface, In the path, the light of the S-polarized component that has passed through the optical path coupling / separating means and the separating / optical path dividing means without rotating the plane of polarization by the first Faraday rotation element and the first half-wave plate; The P-polarized component light that has passed through the optical path coupling / separating means and the separating / optical path dividing means without rotating the polarization plane by the second Faraday rotation element and the second half-wave plate is converted to the P light.
Separating means for separating a polarized light component and an s-polarized light component; and a conjugate position with respect to the condensing position of the light of the p-polarized light component condensed by the condensing means, and the light receiving surface is concentric. A first light receiving unit that detects the intensity of the light of the collected P-polarized component, and is disposed at a conjugate position with respect to the light-collecting position of the S-polarized light collected by the light collecting unit; And a light-receiving surface is divided concentrically, a second light-receiving means for detecting the intensity of the light of the collected S-polarized light component, and the intensity of each of the detected light, An optical displacement meter, comprising: an arithmetic unit for determining a displacement of an object surface. 6. A light source means for measuring displacement of an object surface, a lens means for converting light emitted from the light source means into parallel light, and a P-polarized light component which is converted into parallel light by the lens means. Separation / optical path splitting means for splitting the optical path of the light into a first optical path for the P-polarized light component and a second optical path for the S-polarized light component by separating the light into S-polarized light and S-polarized light. In the first optical path, the polarization plane of the light is rotated by 45 ° in the same direction in the forward and reverse directions.
A first Faraday rotator to rotate, and a polarization plane of light by 45 ° in opposite directions in the forward and reverse directions
A first half-wave plate to be rotated; and wherein in the second optical path, the polarization plane of light is rotated by 45 ° in the same direction in the forward and reverse directions.
A second Faraday rotator to rotate, and a polarization plane of light by 45 ° in opposite directions in the forward and reverse directions
A second half-wave plate for rotating, and lens means for slightly converging or diverging the light whose polarization plane has been rotated by 90 ° in the second optical path, wherein the first Faraday rotation element and The S-polarized light obtained by rotating the polarization plane of the P-polarized light by 90 ° by the first half-wave plate and the S-polarized light by the second Faraday rotator and the second half-wave plate. By combining the light of the polarization component with the light of the P polarization component obtained by rotating the polarization plane of the light by 90 ° into one light flux, the optical paths are combined, or the light is combined with the light of the P polarization component and the S light. An optical path combining / separating means for separating the light into a polarized light component; and a light condensing position different between the P-polarized light component and the S-polarized light component due to the convergence or divergence of the combined light beam by the lens means. Focusing means for focusing light on The optical path coupling / separation means, the lens means, and the separation / optical path division means are reflected on the object surface without rotating the plane of polarization by the first Faraday rotation element and the first half-wave plate in the first optical path. The S-polarized light component and the P light that has passed through the optical path coupling / separating means and the separating / optical path dividing means without rotating the plane of polarization in the second optical path by the second Faraday rotator and the second half-wave plate. Separating means for separating the light of the polarized light component into the p-polarized light component and the s-polarized light component; and a conjugate position with respect to the light collecting position of the light of the p-polarized light component collected by the light collecting means. A first light receiving means for detecting the intensity of the condensed P-polarized light component, the light receiving surface of which is concentrically divided; and a light-condensing light of the S-polarized light component condensed by the light condensing means. Placed at a conjugate position relative to the position And a light receiving surface divided concentrically, a second light receiving means for detecting the intensity of the condensed S-polarized light, and the object in the optical axis direction based on the detected intensity of each light. An optical displacement meter comprising: a calculating means for determining a displacement of a surface; 7. A first light source for emitting light of a first wavelength for measuring displacement of an object surface, and a second light source for emitting light of a second wavelength for measuring displacement of an object surface. Means, lens means for slightly converging or diverging the light of the second wavelength, and combining the light of the first wavelength and the light of the second wavelength into one light flux, or combining the light with the first light. Wavelength light and the second
A dichroic mirror that separates the light into light having a wavelength; a condensing unit that condenses the combined light at different condensing positions near the object surface by different convergence or divergence functions of the lens unit; Is arranged at a conjugate position with respect to the light condensing position of the light of the first wavelength condensed, and the light receiving surface is divided concentrically, reflected on the surface of the object, and passed through the dichroic mirror. A first light receiving means for detecting the intensity of the light, and a light receiving surface arranged concentrically with respect to the light condensing position of the light of the second wavelength condensed by the light condensing means, and the light receiving surface is concentric. A first light receiving unit that detects the intensity of the second wavelength light that is divided and reflected on the object surface and that has passed through the dichroic mirror and the lens unit; and Calculating means for calculating the displacement of the surface of the object in the direction of the optical axis. 8. A first light source means for emitting light of a first wavelength for measuring displacement of an object surface, and a second light source for emitting light of a second wavelength for measuring displacement of an object surface. Means, lens means for slightly converging or diverging the light of the second wavelength, and combining the light of the first wavelength and the light of the second wavelength into one light flux, or combining the light with the first light. Wavelength light and the second
A dichroic mirror that separates the light into light having a wavelength; a condensing unit that condenses the combined light at different condensing positions near the object surface by different convergence or divergence functions of the lens unit; A first minute aperture means disposed at a conjugate position with respect to the light condensing position of the first wavelength light condensed by On the other hand, a second micro aperture means disposed at a conjugate position, a first light receiving means for detecting the intensity of light of a first wavelength passing through the first micro aperture means, and a second micro aperture means Second light receiving means for detecting the intensity of the light of the second wavelength that has passed through; and calculating means for calculating displacement of the object surface in the optical axis direction from the detected intensities of the respective lights. Optical variable Rank meter. 9. The optical displacement meter according to claim 7, wherein said condensing means is an optical means capable of setting a radiation angle of light radiated from each light source to a different position. . 10. The optical displacement meter according to claim 7, wherein the light condensing means is a lens means having chromatic aberration. 11. A step of converting light for measuring the displacement of the surface of the object into parallel light, and converging the parallel light near the surface of the object with different light condensing positions for the P-polarized light component and the S-polarized light component. Separating the P-polarized component light and the S-polarized component light reflected by the object surface into the P-polarized component light and the S-polarized component light; and focusing the P-polarized component light on the object. Passing the received P-polarized component light through a first minute aperture located at a conjugate position with respect to the condensing position, and receiving the S-polarized component light with the collected S-polarized component light Receiving the light by passing through a second micro-aperture located at a conjugate position with respect to the light-condensing position; and obtaining the displacement of the object surface in the optical axis direction from the intensity of each of the received light. And a displacement measuring method comprising: . 12. A step of converting light for measuring the displacement of an object surface into parallel light, and condensing the parallel light near the object surface with different light condensing positions for a P-polarized light component and an S-polarized light component. Separating the P-polarized component light and the S-polarized component light reflected by the object surface into the P-polarized component light and the S-polarized component light; and focusing the P-polarized component light on the object. Receiving at a concentrically divided light receiving surface located at a conjugate position with respect to the condensing position of the light of the P-polarized light component, and converting the light of the S-polarized light component to the light of the collected S-polarized light component Receiving light at a concentrically divided light receiving surface located at a conjugate position with respect to the light condensing position, and obtaining a displacement of the object surface in an optical axis direction from the intensity of each of the received light. Displacement measurement characterized by including Method. 13. A method of converting light into parallel light for measuring displacement of an object surface, and rotating a polarization plane of the parallel light by 90 ° in one direction by a Faraday rotator and a first half-wave plate. And rotating the polarization plane by 90 ° by the Faraday rotator and the first half-wave plate with the P-polarized component and S
Condensing light in the vicinity of the object surface with different light condensing positions with the polarized light components, and the light of the P-polarized light component and the S-polarized light component reflected on the object surface, without rotating the polarization plane as a result, Passing the light through the Faraday rotator and the first half-wave plate;
Separating the P-polarized component light and the S-polarized component light into light; and rotating the polarization plane of the separated polarized light component by 45 ° using a second half-wave plate. Separating the light whose polarization plane has been rotated by the half-wave plate into a P-polarized component and an S-polarized component; and condensing the P-polarized component light with the condensed P-polarized component light A step of receiving light on a concentrically divided light receiving surface located at a conjugate position with respect to the position; and a conjugate position of the S-polarized component light with respect to the condensed position of the collected S-polarized component light. A step of receiving light on a concentrically divided light receiving surface located at a position; and a step of obtaining a displacement of the object surface in an optical axis direction from an intensity of each of the received light. Method. 14. A step of slightly converging or diverging light for measuring a displacement of an object surface, and combining the converged or divergent light with a first optical path having P-polarized light components having different optical path lengths. Dividing the polarization plane of the light of the P-polarized component by the first Faraday rotator and the first half-wave plate in the first optical path. Rotating the light by 90 ° in one direction to generate S-polarized light; and, in the second optical path, changing the polarization plane of the S-polarized light by a second Faraday rotation element and a second half-wave plate. Rotating by 90 ° in one direction to generate P-polarized light; combining the S-polarized light from the first optical path and the P-polarized light from the second optical path into one light flux; And combining the combined luminous flux with the first light By the action of the optical path length difference between the path and the second optical path and the convergence or divergence of the light, P
Condensing light near the object surface with different light condensing positions for the polarization component and the S polarization component, and separating the light beam reflected on the object surface into light of the P polarization component and light of the S polarization component In the first optical path, the P reflected by the object surface
The light of the polarization component and the S-polarization component passing through the first Faraday rotator and the first half-wave plate without rotating the polarization plane as a result; and in the second optical path, The P reflected on the object surface
Light of the polarization component and the S-polarization component passing through the second Faraday rotator and the second half-wave plate without rotating the plane of polarization as a result; and returning from the first optical path. Combining the S-polarized component light and the P-polarized component light returned from the second optical path into one light flux again to combine the first optical path and the second optical path with each other; Separating the light of the P-polarized component into light of the S-polarized component, and dividing the light of the P-polarized component into concentric circles located at conjugate positions with respect to the condensing position of the collected P-polarized light. Receiving the S-polarized component light on a concentrically divided light-receiving surface located at a conjugate position with respect to the condensing position of the collected S-polarized component light. And the intensity of each of the received light, the object in the optical axis direction Displacement measuring method characterized by comprising a step of determining the displacement of the surface. 15. A step of converting light for measuring a displacement of an object surface into parallel light, a first optical path on a P-polarized component having substantially the same optical path length, and the S-polarized component. And a second optical path according to the above, and in the first optical path, the polarization plane of the light of the P-polarized component is 90 ° in one direction by a first Faraday rotation element and a first half-wave plate. Rotating the light into an S-polarized light component; further, slightly converging or diverging the 90-degree rotated light in the first optical path; and performing a second Faraday rotation in the second optical path. Rotating the polarization plane of the S-polarized light by 90 ° in one direction by the element and the second half-wave plate to make the P-polarized light; and the S-polarized light from the first optical path. And light of the P-polarized component from the second optical path. Combining the combined light beam into one light beam, and condensing the combined light beam in the vicinity of the object surface with different light condensing positions for the P-polarized light component and the S-polarized light component by the action of convergence or divergence of the light, Separating the light beam reflected by the object surface into the P-polarized light component and the S-polarized light component; and the P light reflected by the object surface in the first optical path.
The light of the polarization component and the S-polarization component passing through the first Faraday rotator and the first half-wave plate without rotating the polarization plane as a result; and in the second optical path, The P reflected on the object surface
Light of the polarization component and the S-polarization component passing through the second Faraday rotator and the second half-wave plate without rotating the plane of polarization as a result; and returning from the first optical path. Combining the S-polarized component light and the P-polarized component light returned from the second optical path into one light flux again to combine the first optical path and the second optical path with each other; Separating the light of the P-polarized component into light of the S-polarized component, and dividing the light of the P-polarized component into concentric circles located at conjugate positions with respect to the condensing position of the collected P-polarized light. Receiving the S-polarized component light on a concentrically divided light-receiving surface located at a conjugate position with respect to the condensing position of the collected S-polarized component light. And the intensity of each of the received light, the object in the optical axis direction Displacement measuring method characterized by comprising a step of determining the displacement of the surface. 16. A first method for measuring a displacement of an object surface.
Emitting light of a wavelength; emitting light of a second wavelength for measuring displacement of the surface of the object; slightly converging or diverging the light of the second wavelength; Combining the light and the light of the second wavelength into one light flux; and combining the combined light with different converging positions due to the convergence or divergence of the light of the second displacement meter. Condensing the light beam reflected by the object surface into light of the first wavelength and light of the second wavelength; and collecting the light of the first wavelength into the condensed first light. Receiving at a concentrically divided light receiving surface located at a conjugate position with respect to the light condensing position of the light of the wavelength; and transmitting the light of the second wavelength to the light of the collected light of the second wavelength. Concentrically divided light-receiving surface located at a conjugate position with respect to the light position A displacement measuring method, comprising: receiving light; and obtaining a displacement of the surface of the object in an optical axis direction from an intensity of each of the received light. 17. A first method for measuring a displacement of an object surface.
Emitting light of a wavelength; emitting light of a second wavelength for measuring displacement of the surface of the object; slightly converging or diverging the light of the second wavelength; Combining the light and the light of the second wavelength into one light flux; and combining the combined light with different converging positions due to the convergence or divergence of the light of the second displacement meter. Condensing the light beam reflected by the object surface into light of the first wavelength and light of the second wavelength; and collecting the light of the first wavelength into the condensed first light. Receiving the light having the wavelength by passing through the first minute aperture located at the conjugate position with respect to the light condensing position of the light having the wavelength; Light is received by passing through the second minute aperture located at a conjugate position with respect to the light position And measuring a displacement of the surface of the object in an optical axis direction from an intensity of each of the received lights. 18. The method according to claim 16, wherein the step of converging light near the surface of the object with different light condensing positions at the first wavelength and the second wavelength is performed using lens means having chromatic aberration. Or the displacement measuring method according to 17.