CN103673888A - Optical displacement meter and optical displacement calculating method - Google Patents

Abstract

The invention provides an optical displacement meter provided with a light source radiating first light containing a plurality of wavelengths; an objective lens radiating the first light emitted by the light source, so as to enable each one of the wavelength to focus on different positions on an optical axis; a separation part separating the second light passing through the objective lens from the reflection light from a sample and emitting a third light; an optical element emitting a fourth light making the third light have aberration and similarity indexes; a plurality of detection parts used for detecting the fourth light emitted from the optical element; and an operation part calculating height of a sample from a referential face based on the fourth light detected by the detection parts.

Description

Optical Displacement Meter and Optical Displacement Calculation Method

technical field

The present invention relates to an optical displacement gauge and an optical displacement computing method, in particular, to an optical displacement gauge and an optical displacement computing method that realize miniaturization, low cost, and high-speed response.

Background technique

FIG. 6 is a configuration diagram of a conventional first optical displacement gauge 200a. Specifically, FIG. 6 is a configuration diagram of an optical displacement gauge 200a described in Japanese Patent Application Laid-Open No. 10-9827.

In FIG. 6 , light emitted from a white light source 201 such as an Xe lamp and containing multiple wavelength components passes through a pinhole 206 a , passes through a beam splitter 203 , is focused by an objective lens 204 , and is irradiated onto a sample 205 .

The light reflected on the sample 205 is reflected by the beam splitter 203, and enters the photodetector 207 through the pinhole 206b. The photodetector 207 has color filters 208a and 208b and light-receiving sensors 209R, 209G and 209B. The color filters 208a and 208b are dichroic mirrors that split incident light into three primary colors. The light receiving sensors 209R, 209G, and 209B are sensors that receive light of three primary colors.

Generally, the focal length f of a lens is approximately represented by the following formula (1).

(1/f)=(n-1)×{(1/r1)-(1/r2)}...(1)

In formula (1), n is the refractive index of the glass material constituting the lens, and r1 and r2 are the radii of curvature of the lens.

As shown in the above formula (1), the focal length f depends on the refractive index n of the lens. The refractive index n of the lens depends on the wavelength λ of the passing light. Accordingly, the in-focus position of light corresponds to the wavelength λ, and differs in the direction of the optical axis.

In the description of FIG. 6 , the case where the length of the wavelength is λ1<λ2<λ3 will be described.

As shown in FIG. 6 , if the light of wavelength λ2 is in focus on the top of the sample 205, the light of wavelength λ1 is in focus in front of the sample 205 (above the paper in FIG. 6 ) due to its shorter focal length. In addition, the light of the wavelength λ3 is in focus behind the sample 205 (the lower side of the paper in FIG. 6 ) because of its long focal length.

For example, when the light of wavelength λ1 is B (blue), the light of wavelength λ2 is G (green), and the light of wavelength λ3 is R (red), the light of wavelength λ2 that is in focus on the top of the sample 205 is the most The ground enters the light-receiving sensor 209G through the color filters 208a and 208b. The processing unit 210a detects that the light receiving sensor 209G receives the largest amount of light received by the light receiving sensors 209B, 209G, and 209R, and determines the height of the sample 205 from the reference plane R0 as the in-focus position of the green light.

FIG. 7 is a configuration diagram of a conventional second optical displacement gauge 200b. In FIG. 7 , a line sensor 214 is provided in the photodetector 207 .

In FIG. 7 , the light incident on the photodetector 207 after passing through the pinhole 206 a becomes parallel light by the lens 211 . The parallel light is split into light of each wavelength component by the triangular prism 212 serving as a spectral beam splitter. The split light is focused by the lens 213 . Then, the condensed light is incident into a line sensor 214 constituted by a CCD (Charge Combined Device) or the like.

In this structure, in the case where the light reflected from the top of the sample 205 is green light of the wavelength λ2, the most light is irradiated on the position on the line sensor 214 corresponding to the wavelength λ2.

Therefore, the processing unit 210 b can obtain the height of the sample 205 from the light receiving position of the line sensor 214 by obtaining the relationship between the height of the sample 205 and the light receiving position of the line sensor 214 in advance.

FIG. 8 is a configuration diagram of a third optical displacement gauge 200c as a conventional technology. Specifically, FIG. 8 is a configuration diagram of an optical displacement gauge 200c described in JP 2011-39026. In FIG. 8 , on the optical axis, for the objective lens 204 with large chromatic aberration, the focal length varies with the wavelength (color) of light. That is to say, the blue light B0 is focused at a position closer to the objective lens 204 , and the red light R0 is focused at a position farther from the objective lens 204 . The green light G0 is in focus at a position between the in-focus position of the blue light B0 and the in-focus position of the red light R0 . The optical displacement meter 200c measures the sample 205 in the measurement range M0. In JP 2011-39026, the sample 205 to be measured and the confocal point on the opposite side with respect to the objective lens 204 are considered to be the same regardless of the color. If a white or broadband point light source is configured, corresponding to the height of the sample 205 , the color in focus on the sample 205 changes in a one-to-one relationship. Therefore, if a spatial filter such as a pinhole is provided at the confocal position when the reflected light from the sample 205 returns, and the reflected light passes, light of the color in focus on the sample 205 can be extracted. This principle is utilized in JP 2011-39026.

In addition, in Japanese Patent Application Laid-Open No. 2011-39026, a color (wavelength of light) is designated by using a spectrometer 226 such as a diffraction grating in the processing unit 210c, thereby measuring the height (displacement) of the sample 205 in a one-to-one correspondence with the color. ).

Generally, optical fiber 230 is used to guide white light (broadband light) to the confocal point of sensor head 215 , and the core of fiber end face 230 a is considered as a pinhole and as confocal point, and divergent light is applied to collimating lens 216 .

After being reflected by the sample 205 , among the white light irradiated on the sample 205 , the light of the color in focus on the sample 205 is selectively concentrated at the confocal position of the fiber end face 230 a. The light concentrated at the confocal position enters the fiber core and is guided to the beam splitter 226 through the fiber coupler 224 . On the other hand, for light of other colors, the core of the fiber end face 230a acts as a pinhole to limit the incident light. As a result, light other than the light of the color in focus on the sample 205 is blocked by the outer periphery of the fiber core and does not enter the optical fiber 230 .

Beam splitter 226 detects the wavelength of light returning within optical fiber 230 . The wavelength detected by the spectrometer 226 is input to the electronic circuit 228 and processed.

Using the three-path optical displacement gauge 200a using the dichroic mirror shown in FIG. 6 above increases the size of the device. In addition, the price of the dichroic mirror is high, and there are limitations in the accuracy of the measurement range, which increases the cost.

In addition, the optical displacement gauge 200b using the above-mentioned prism 212 and line sensor 214 shown in FIG. 7 increases the size of the device. In addition, the line sensor 214 is expensive, and the reading speed cannot be increased.

In addition, in the optical displacement gauge 200c using the spectroscope 226 shown in FIG. 8, the spectroscope 226 and the electronic circuit 228 are expensive.

Contents of the invention

The present invention provides an optical displacement meter and an optical displacement calculation method, which reduce the manufacturing cost of the device, increase the readout speed, and miniaturize the device.

(1) A first aspect of the present invention is an optical displacement meter that includes: a light source that irradiates first light including a plurality of wavelengths; an objective lens that irradiates the first light irradiated by the light source to a sample, and Each of the aforementioned plurality of wavelengths is brought into focus at a different position on the optical axis; a separation unit separates the second light that passes through the aforementioned objective lens from among the reflected light from the aforementioned sample, and emits a third light; an optical element , which emits fourth light obtained by causing chromatic aberration and astigmatism to the third light emitted by the separation unit; a plurality of detection units, which detect the fourth light emitted by the optical element; and a calculation unit, based on The said 4th light detected by the said some detection part calculates the height of the said sample from a reference plane.

(2) In the first aspect of the present invention, the separating unit is a fiber coupler, and spatially separates the second light and emits it as the third light.

(3) The first aspect of the present invention may include: a first optical fiber that allows the first light irradiated by the light source to enter from one end and emits the first light from the other end; and a second optical fiber that uses The separation unit emits the third light separated from the second light.

(4) In the first aspect of the present invention, the other end of the first optical fiber is disposed at a confocal position with respect to the surface of the sample.

(5) In the first aspect of the present invention, the separating unit is a beam splitter that separates the second light into reflected light and transmitted light, and emits the separated reflected light as the third light.

(6) The first aspect of the present invention may include: a first pinhole for allowing the first light irradiated by the light source to enter from one side and to emit the first light from the other side; and a second pinhole. The hole allows the second light to enter from one side and emits the second light as the third light from the other side.

(7) In the first aspect of the present invention, the first pinhole may be disposed at a confocal position with respect to the sample.

(8) In the first aspect of the present invention, the second pinhole may be disposed at a confocal position with respect to the sample.

(9) The first aspect of the present invention further includes a housing including the objective lens and the second pinhole, and the first pinhole is provided on the housing.

(10) In the first aspect of the present invention, the optical element may be a chromatic aberration lens or a cylindrical lens.

(11) In the first aspect of the present invention, the optical element may be parallel plate glass arranged on the optical axis of the fourth light and inclined with respect to the optical axis of the fourth light.

(12) In the first aspect of the present invention, the plurality of detection units may be composed of first to fourth photodiodes.

(13) In the first aspect of the present invention, when the values detected by the first to fourth photodiodes are A1, B1, C1, and D1, respectively, ((A1+B1)-(C1+ The relationship of D1)/(A1+B1+C1+D1)) is calculated for the height of the sample from the reference plane.

(14) In the first aspect of the present invention, the first to fourth photodiodes may be arranged at vertices of a square perpendicular to the optical axis of the fourth light.

(15) In the first aspect of the present invention, the plurality of detection units may be constituted by first and second photodiodes.

(16) In the first aspect of the present invention, a storage unit may be provided for storing the height of the sample from the reference plane in association with calculation results of the output signals of the plurality of detection units, The calculation unit reads the height of the sample from the storage unit based on calculation results of the output signals of the plurality of detection units.

(17) In the first aspect of the present invention, a moving part that moves the optical displacement gauge parallel to the reference plane may be provided, and the calculating part moves the optical displacement gauge in the moving part. In the process, the height of the aforementioned samples is calculated.

(18) A second aspect of the present invention is an optical displacement meter including: a first light source that irradiates first light including a plurality of wavelengths; The light is irradiated to the sample so that each of the aforementioned plurality of wavelengths is focused at a different position on the optical axis; 2. The light is separated to emit the third light; the first optical element emits the fourth light obtained by causing chromatic aberration and astigmatism to the third light emitted by the first separation part; the plurality of first detection parts Detecting the aforementioned 4th light emitted by the aforementioned 1st optical element; the 2nd light source, which irradiates the 5th light including a plurality of wavelengths; the 2nd objective lens, which irradiates the aforementioned 5th light irradiated by the aforementioned 2nd light source to the sample, so that each of the aforementioned plurality of wavelengths is in focus at a different position on the optical axis; the second separation part separates the sixth light that passes through the aforementioned second objective lens among the reflected light from the other surface of the aforementioned sample , to emit the 7th light; the 2nd optical element, which emits the 8th light obtained by causing chromatic aberration and astigmatism to the aforementioned 7th light emitted by the aforementioned 2nd separation unit; The eighth light emitted by the optical element is detected; and the calculation unit is configured to perform a first height measurement on the first surface side of the sample from the reference plane based on the fourth light detected by the plurality of first detection units. calculation, and based on the aforementioned eighth light detected by the plurality of second detection parts, the second height of the other surface side of the aforementioned sample from the aforementioned reference plane is calculated, and then based on the aforementioned first height and the aforementioned first 2 Height, calculate the thickness of the aforementioned sample.

(19) A third aspect of the present invention is an optical displacement calculation method, that is, the first light including a plurality of wavelengths is irradiated from the light source, and the first light irradiated by the light source is irradiated from the objective lens to the sample, so that the above-mentioned Each of the plurality of wavelengths is focused at a different position on the optical axis, and the reflected light from the sample is separated by the second light separation unit of the objective lens by the separation unit, and the third light is emitted. The element emits fourth light obtained by causing chromatic aberration and astigmatism to the third light emitted by the separation unit, and the fourth light emitted by the optical element is detected by a plurality of detection units. The height of the sample from the reference plane is calculated by the calculation unit for the fourth light.

(20) The fourth aspect of the present invention is the following optical displacement calculation method, that is, the first light including a plurality of wavelengths is irradiated from the first light source, and the first light irradiated by the first light source is directed from the first objective lens to The sample is irradiated so that each of the plurality of wavelengths is in focus at a different position on the optical axis, and the second light that passes through the first objective lens among the reflected light from one surface of the sample is analyzed by the first separation part. The third light is separated to emit the third light, and the fourth light obtained by causing chromatic aberration and astigmatism to the aforementioned third light emitted by the first splitting part is emitted from the first optical element, and the aforementioned first optical light is detected by a plurality of first detection parts. The aforementioned fourth light emitted by the element is detected, and the fifth light including multiple wavelengths is irradiated from the second light source. Each of them is focused at a different position on the optical axis, and the sixth light that passes through the second objective lens is separated from the reflected light from the other surface of the sample by the second separation part, and the seventh light is emitted from the The second optical element emits eighth light obtained by causing chromatic aberration and astigmatism to the seventh light emitted from the second separation unit, and the plurality of second detection portions detects the eighth light emitted from the second optical element. , based on the above-mentioned fourth light detected by the plurality of first detection parts, the calculation part is used to calculate the first height of the first surface side of the aforementioned sample from the reference plane, and based on the detection of the plurality of second detection parts The above-mentioned 8th light emitted is calculated by the calculation unit on the second height of the other surface side of the sample from the reference plane, and then based on the first height and the second height, the calculation unit calculates The thickness of the aforementioned sample is calculated.

According to the present invention, it is possible to provide an optical displacement meter and an optical displacement calculation method that reduce the manufacturing cost of the device, increase the readout speed, and reduce the size of the device.

Description of drawings

FIG. 1 is a configuration diagram of main parts of an optical displacement gauge according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which reflected light has different ellipticities on the surface of four photodiodes.

Fig. 3 is a configuration diagram of main parts of an optical displacement gauge according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of main parts of an optical displacement gauge according to a third embodiment of the present invention.

Fig. 5 is a configuration diagram of main parts of an optical displacement gauge according to a fourth embodiment of the present invention.

Fig. 6 is a configuration diagram of a first optical displacement meter as a prior art.

Fig. 7 is a configuration diagram of a second conventional optical displacement meter.

Fig. 8 is a configuration diagram of a third conventional optical displacement meter.

Detailed ways

Next, first to fourth embodiments of the present invention will be described with reference to the drawings. The following descriptions related to the first to fourth embodiments of the present invention are intended to specifically describe the inventions defined in the appended claims and their equivalents, and are not intended to limit them. It is understandable to say based on the present disclosure.

(first embodiment)

First, the optical displacement gauge 100a of the first embodiment will be described.

Fig. 1 is a configuration diagram of main parts of an optical displacement gauge 100a according to a first embodiment of the present invention.

In FIG. 1 , a light source 101 is a white light source that emits light including a plurality of wavelengths. The light irradiated by the light source 101 enters into the optical fiber 130a. The light incident into the optical fiber 130a is emitted from the emission port 130c of the optical fiber 130a. The imaging optical system 140 a has a fiber coupler 124 and an objective lens 104 . The sample 105 is arranged on the opposite side to the fiber coupler 124 across the objective lens 104 . The objective lens 104 is a chromatic aberration lens. The light transmitted through the objective lens 104 is irradiated on the sample 105 .

Here, light of wavelength λ1 (blue), light of wavelength λ2 (green), and light of wavelength λ3 (red) are generated from the sample 105 as reflected light. In addition, the emission port 130c of the optical fiber 130a can be regarded as a point light source. The emission port 130c of the optical fiber 130a is disposed at a confocal position with respect to the surface of the sample 105 .

The reflected light reflected by the sample 105 reverses the same path as the incident path, is spatially separated by the fiber coupler 124 provided on the optical fiber 130a, and enters the reflected light imaging optical system 141a via the optical fiber 130b.

The reflected light imaging optical system 141 a has a chromatic aberration lens 104 a, a cylindrical lens 143 and a quadrant photodiode 144 .

The reflected light emitted from the emission port 130d of the optical fiber 130b passes through the chromatic aberration lens 104a for emitting the reflected light to a focus position whose distance varies depending on the wavelength. The light transmitted through the chromatic aberration lens 104 a is transmitted through a cylindrical lens (cylindrical lens) 143 .

The cylindrical lens 143 causes astigmatism in the reflected light, and forms an imaging shape depending on the wavelength on the surface of the quadrant photodiode 144 . With the cylindrical lens 143, light contained in a surface having a curved section in section is condensed, while light contained in a surface having no curved section in section is not condensed. As a result, when the light transmitted through the cylindrical lens 143 is observed on a surface perpendicular to the optical axis, it generally has an elliptical intensity distribution.

The cylindrical lens 143 is used to generate astigmatism. In addition, other elements may be used as long as they serve the same role as the cylindrical lens 143 . As an example of this element, an optical system that is not rotationally symmetric with respect to the optical axis can be used, and parallel plate glass arranged obliquely on the optical axis can be used.

FIG. 2 is a diagram showing how the reflected light has different ellipticities on the surface of the four-divided photodiode 144 . Specifically, the window W1 in FIG. 2 shows the following situation, that is, the reflected light emitted from the output port 130d of the optical fiber 130b shown in FIG. 4 divided photodiodes 144 . Window W2 in FIG. 2 shows a state in which the surface of the photodiode 144 has different ellipticities in four parts.

As shown in FIG. 2 , the four photodiodes 144 include photodiodes 144A, 144B, 144C, and 144D. FIG. 2 shows a case where photodiodes 144A, 144B, 144C, and 144D are arranged at vertices of a square perpendicular to the optical axis of light emitted by cylindrical lens 143 .

Outputs from the four-divided photodiodes 144 are respectively input to the calculation unit 142, and the outputs of the quarter-divided photodiodes 144 are calculated to obtain information on the shape of the image on the detection surface. For example, if the outputs of the photodiodes 144A, 144B, 144C, and 144D in FIG. 2 are used as A1, B1, C1, and D1, then only ((A1+B1)-(C1+D1)/(A1+B1+C1+ The calculation of D1)) is sufficient, and it is a positive value in the case of a vertically long shape, and a negative value in the case of a horizontally long shape. Since the wavelength can be determined from the calculation result, the height of the sample 105 from the reference plane (thickness of the sample 105 ) can finally be obtained. For example, the calculation unit 142 has a storage unit (not shown in the figure) that stores in advance the height of the surface of the sample 105 from the reference plane R1 and the calculation results of the output signals of the photodiodes 144A, 144B, 144C, and 144D in association with each other. . When the calculation results of the output signals of the photodiodes 144A, 144B, 144C, and 144D are obtained, the calculation unit 142 reads the height corresponding to the calculation results from the storage unit, and specifies the height of the surface of the sample 105 from the reference plane R1. .

In addition, as the computing unit 142, an electric circuit, a microcomputer, a microcontroller, or the like can be used.

In the first embodiment, the quadrant photodiode 144 is used as the detection element of the light emitted from the cylindrical lens 143, but the present invention is not limited thereto. For example, an element whose intensity ratio of a plurality of detection elements changes according to a change in the imaging shape may be used as the detection element. For example, instead of using the four-divided photodiode 144, two divided photodiodes may be used as detection elements.

(Second embodiment)

Next, an optical displacement gauge 100b according to a second embodiment of the present invention will be described. In addition, the same code|symbol is attached|subjected to the part which employ|adopted the same structure as 1st Embodiment in 2nd Embodiment, and the description of them is abbreviate|omitted.

Fig. 3 is a configuration diagram of main parts of an optical displacement gauge 10b according to a second embodiment of the present invention. In the second embodiment, the difference from the first embodiment is that: instead of the optical fibers 130a, 130b, pinholes 106a, 106b are used; the reflected light from the sample 105 is separated by the beam splitter 103; The reflected light is incident into the reflected light imaging optical system 141b through the pinhole 106b.

The imaging optical system 140 b according to the second embodiment has a pinhole 106 a , a pinhole 106 b , and a chromatic aberration lens 104 .

In FIG. 3 , the light irradiated by the light source 101 is introduced into the imaging optical system 140 b through the first pinhole 106 a. The pinholes 106 a and 106 b are arranged at a confocal position with respect to the surface of the sample 105 .

In addition, a beam splitter is arranged between the pinhole 106a and the surface of the sample 105 as a separation part for spatially separating the paths of reflected light, and a second pinhole is arranged at a position where the reflected light separated by the beam splitter 103 is focused. 106b. Since other configurations and functions of the reflected light imaging optical system 141 b are the same as those of the reflected light imaging optical system 141 a according to the first embodiment shown in FIG. 1 , description thereof will be omitted.

The optical displacement gauge 100b configured as shown in FIG. 3 functions in the same manner as the optical displacement gauge 100a according to the first embodiment shown in FIG. 1 .

(third embodiment)

Next, an optical displacement gauge 100c according to a third embodiment of the present invention will be described. In addition, the same code|symbol is attached|subjected to the part which employ|adopts the same structure as 2nd Embodiment about 3rd Embodiment, and the description of them is abbreviate|omitted.

Fig. 4 is a configuration diagram of main parts of an optical displacement gauge 10c according to a third embodiment of the present invention. In the third embodiment, the difference from the first embodiment is that: instead of the optical fibers 130a, 130b, pinholes 106a, 106b are used; The reflected light is incident into the reflected light imaging optical system 141b through the pinhole 106b.

In addition, the third embodiment differs from the second embodiment in that the pinhole 106 a is not provided inside the imaging optical system 140 b as in the second embodiment shown in FIG. 3 . Specifically, in the third embodiment, the cubic housing 1400 of the imaging optical system 140c includes the objective lens 104 and the pinhole 106b therein. Also, the pinhole 106c is provided at the center of the upper surface of the housing 1400 .

In the third embodiment, since there is no need to separately provide a supporting portion for supporting the light source 101 and the pinhole 101b, the manufacturing cost can be reduced compared with the imaging optical system 140b according to the second embodiment.

In addition, the pinhole 106c is arranged to be at a confocal position with respect to the surface of the sample 105 .

The optical displacement gauge 100c configured as shown in FIG. 4 functions in the same manner as the optical displacement gauge 100a according to the first embodiment shown in FIG. 1 .

(fourth embodiment)

Next, an optical displacement gauge 100d according to a fourth embodiment of the present invention will be described. In addition, the same code|symbol is attached|subjected to the part which employ|adopts the same structure as 1st Embodiment in 4th Embodiment, and the description is abbreviate|omitted.

Fig. 5 is a configuration diagram of main parts of an optical displacement gauge 100d according to a fourth embodiment of the present invention. The optical displacement meter 100d of the fourth embodiment has the imaging optical system 140a and the reflected light imaging optical system 141a similarly to the first embodiment. Furthermore, the optical displacement meter 100d of the fourth embodiment further includes an imaging optical system 140d and a reflected light imaging optical system 141d.

The imaging optical system 140d and the reflected light imaging optical system 141d function in the same manner as the imaging optical system 140a and the reflected light imaging optical system 141a. That is, the light source 301, the optical fibers 330a, 330b, the fiber coupler 324, the chromatic aberration lenses 304, 304a, the cylindrical lens 343, and the quarter photodiode 344 are the same as the light source 101, the optical fibers 130a, 130b described in the first embodiment, respectively. , the fiber coupler 124, the chromatic aberration lenses 104 and 104a, the cylindrical lens 143, and the quadrant photodiode 144 function in the same manner.

In the fourth embodiment, for the sample 105 which is a plate-shaped or thin-plate-shaped measurement object, by arranging the pair of imaging optical systems 140a and 140d on both sides of the sample 105 and performing the measurement respectively, the value of the sample 105 can be calculated. thickness.

That is, the optical displacement gauge 100d of the fourth embodiment has: a light source 101 that irradiates first light including a plurality of wavelengths; Each of the wavelengths λ1, λ2, and λ3 is focused at a different position on the optical axis; the fiber coupler 124 separates the second light that passes through the objective lens 104 from the reflected light from one surface of the sample 105, and emits The 3rd light; Chromatic aberration lens 104a, it emits the 4th light that makes the 3rd light that fiber coupler 124 emits produce chromatic aberration to obtain; the fifth light; and four photodiodes 144 for detecting the fifth light emitted by the cylindrical lens 143 .

In addition, the optical displacement gauge 100d of the fourth embodiment includes: a light source 301 that emits sixth light including a plurality of wavelengths λ1, λ2, and λ3; In order to make each of the multiple wavelengths λ1, λ2, and λ3 focus at different positions on the optical axis; the fiber coupler 324 is used for the seventh light passing through the objective lens 304 in the reflected light from the other surface of the sample 105 Separation is carried out to emit the 8th light; Chromatic aberration lens 304a, which emits the 9th light obtained by causing chromatic aberration to the 8th light emitted by the fiber coupler 324; Cylindrical lens 343, which emits the 9th light emitted by the achromatic lens 304a to generate The tenth light obtained by astigmatism; and the quadrant photodiode 344 that detects the tenth light emitted by the cylindrical lens 343 .

In addition, the optical displacement gauge 100d of the fourth embodiment has a calculation unit 142d that calculates the first height H1 on the one surface side of the sample 105 from the reference plane R1 based on the fifth light detected by the photodiode 144. The calculation is based on the tenth light detected by the four-point photodiode 344, and the second height H2 of the other surface side of the sample 105 from the reference plane R1 is calculated, based on the first and second heights H1 and H2, the sample The thickness of 105 (the sum of the first height and the second height) is calculated.

In addition, in the case where the 4-divided photoelectrode tube 144 and the 4-divided photodiode 344 arranged on both sides can be relatively displaced in the optical axis direction of the imaging optical system 140a, 140b, by additionally providing the 4-divided photoelectrode tube 144 An instrument that measures the distance from the photodiode 344 can accurately calculate the thickness of the measurement object.

According to the configurations of the optical displacement gauges 100a to 100d according to the first to fourth embodiments, low-cost instruments ( chromatic aberration lens 104a, cylindrical lens 143). Thereby, reflected-light imaging optical systems 141a, 141b, and 141d can be configured at a cost lower than that of commercially available beam splitters.

In addition, the 4-splitting photodiode 144 is less expensive than an array of several hundred to several thousand elements used in a spectroscope, and can operate at high speed.

Furthermore, since the reflected light imaging optical systems 141a, 141b, and 141d are simple optical systems, the optical systems are small and lightweight, and can be applied as sensors for insertion.

In addition, in the optical displacement gauges 100a to 100d according to the first to fourth embodiments of the present invention, a moving part (not shown) may be provided so that the optical displacement gauges 100a to 100d are relative to each other on the reference plane R1. A plate-shaped or thin-plate-shaped measuring object (sample 105 ) moves in parallel. By fixing the sample 105 and moving the optical displacement gauges 100a to 100d in parallel on the reference plane R1 by the moving part, the height of the sample 105 from the reference plane can be measured, and the measurement object on the reference plane of the sample 105 can be accurately measured. height (thickness).

In addition, the above description shows only the specific best mode for the purpose of description and illustration of this invention. For example, a calibration lens may be arranged in the middle of the incident light path or the reflected light path to set the calibration interval.

The present invention is not limited to the above-described embodiments, and changes and deformations can be added without departing from the essence.

Claims (20)

1. An optical displacement meter, which has: a light source that irradiates first light including a plurality of wavelengths; an objective lens, which irradiates the first light irradiated by the aforementioned light source to the sample, so that each of the aforementioned plurality of wavelengths is focused at different positions on the optical axis; a separation unit that separates the second light that passes through the objective lens out of the reflected light from the sample, and emits the third light; an optical element that emits fourth light obtained by causing chromatic aberration and astigmatism to the third light emitted from the separation unit; a plurality of detection units for detecting the fourth light emitted from the optical element; and A calculation unit that calculates the height of the sample from a reference plane based on the fourth light detected by the plurality of detection units. 2. The optical displacement meter according to claim 1, The separating unit is a fiber coupler, and spatially separates the second light and emits it as the third light. 3. The optical displacement meter according to claim 1, which has: A first optical fiber that allows the first light irradiated by the light source to enter from one end and emits the first light from the other end; and A second optical fiber that emits the third light separated from the second light by the splitter. 4. The optical displacement meter according to claim 3, The other end of the first optical fiber is disposed at a confocal position with respect to the surface of the sample. 5. The optical displacement meter according to claim 1, The separating unit is a beam splitter that separates the second light into reflected light and transmitted light, and emits the separated reflected light as the third light. 6. The optical displacement meter according to claim 1, which has: a first pinhole that allows the first light irradiated by the light source to enter from one side and emit the first light from the other side; and The second pinhole allows the second light to enter from one side and emits the second light as the third light from the other side. 7. The optical displacement meter according to claim 6, The first pinhole is arranged so as to be at a confocal position with respect to the surface of the sample. 8. The optical displacement meter according to claim 6, The second pinhole is arranged so as to be at a confocal position with respect to the surface of the sample. 9. The optical displacement meter according to claim 6, It also has a frame that includes the aforementioned objective lens and the aforementioned second pinhole, The aforementioned first pinhole is provided on the aforementioned frame body. 10. The optical displacement meter according to claim 1, The aforementioned optical elements are chromatic aberration lenses and cylindrical lenses. 11. The optical displacement meter according to claim 1, The said optical element is parallel plate glass, and it arrange|positions on the optical axis of the said 4th light, and is inclined with respect to the optical axis of the said 4th light. 12. The optical displacement meter according to claim 1, The plurality of detection units are composed of first to fourth photodiodes. 13. The optical displacement meter according to claim 12, In the case where the values detected by the aforementioned first to fourth photodiodes are A1, B1, C1, and D1 respectively, the formula of ((A1+B1)-(C1+D1)/(A1+B1+C1+D1)) is used The relationship is calculated on the height of the aforementioned sample from the aforementioned reference plane. 14. The optical displacement meter according to claim 12, The first to fourth photodiodes are arranged at vertices of a square perpendicular to the optical axis of the fourth light. 15. The optical displacement meter according to claim 1, The plurality of detection units are composed of first and second photodiodes. 16. The optical displacement meter according to claim 1, It has a storage unit that stores the height of the sample from the reference plane in association with the calculation results of the output signals of the plurality of detection units, The calculation unit reads the height of the sample from the storage unit based on calculation results of the output signals of the plurality of detection units. 17. The optical displacement meter according to claim 1, It has a moving part that moves the aforementioned optical displacement gauge parallel to the aforementioned reference plane, The calculating unit calculates the height of the sample while the moving unit moves the optical displacement gauge. 18. An optical displacement gauge having: a first light source that irradiates first light including a plurality of wavelengths; A first objective lens, which irradiates the first light irradiated by the first light source to the sample, so that each of the plurality of wavelengths is focused at a different position on the optical axis; a first separation unit, which separates the second light that passes through the first objective lens among the reflected light from one surface of the sample, and emits the third light; a first optical element that emits fourth light obtained by causing chromatic aberration and astigmatism to the third light emitted from the first separation unit; a plurality of first detection units for detecting the fourth light emitted by the first optical element; a second light source for irradiating fifth light including a plurality of wavelengths; The second objective lens, which irradiates the aforementioned fifth light irradiated by the aforementioned second light source to the sample, so that each of the aforementioned plurality of wavelengths is focused at different positions on the optical axis; A second separation unit, which separates the sixth light that passes through the second objective lens among the reflected light from the other surface of the sample, and emits the seventh light; a second optical element that emits eighth light obtained by causing chromatic aberration and astigmatism to the seventh light emitted from the second separation unit; a plurality of second detection units that detect the eighth light emitted from the second optical element; and a calculation unit that calculates the first height of the first surface side of the sample from the reference plane based on the fourth light detected by the plurality of first detection units, and based on the detection of the plurality of second detection units. The emitted eighth light calculates the second height from the reference plane on the other surface side of the sample, and then calculates the thickness of the sample based on the first height and the second height. 19. An optical displacement calculation method, irradiating first light including a plurality of wavelengths from a light source, The aforementioned first light irradiated by the aforementioned light source is irradiated from the objective lens to the sample, so that each of the aforementioned plurality of wavelengths is focused at a different position on the optical axis, The second light passing through the objective lens among the reflected light from the sample is separated by the separating part, and the third light is emitted, 4th light obtained by causing chromatic aberration and astigmatism to the 3rd light radiated from the separation part is emitted from the optical element, detecting the fourth light emitted from the optical element by a plurality of detection units, Based on the fourth light detected by the plurality of detection units, the calculation unit calculates the height of the sample from the reference plane. 20. An optical displacement calculation method, irradiating first light including a plurality of wavelengths from a first light source, The aforementioned first light irradiated by the aforementioned first light source is irradiated from the first objective lens to the sample, so that each of the aforementioned plurality of wavelengths is focused at a different position on the optical axis, The second light passing through the first objective lens among the reflected light from one surface of the sample is separated by the first separation unit to emit the third light, 4th light obtained by causing chromatic aberration and astigmatism to the 3rd light radiated from the 1st separating part is emitted from the 1st optical element, detecting the fourth light emitted from the first optical element by a plurality of first detection parts, irradiating the fifth light including a plurality of wavelengths from the second light source, The aforementioned fifth light irradiated by the aforementioned second light source is irradiated from the second objective lens to the sample, so that each of the aforementioned plurality of wavelengths is focused at a different position on the optical axis, The 6th light passing through the 2nd objective lens among the reflected light from the other surface of the sample is separated by the 2nd separation part, and the 7th light is emitted, Eighth light obtained by causing chromatic aberration and astigmatism to the seventh light emitted from the second separation unit is emitted from the second optical element, detecting the eighth light emitted from the second optical element by a plurality of second detection parts, Based on the above-mentioned fourth light detected by the plurality of first detection units, the calculation unit calculates the first height of the first surface side of the aforementioned sample from the reference plane, based on the first height detected by the plurality of second detection units. The eighth light calculates the second height of the sample on the other surface side of the sample from the reference plane by the calculation unit, and calculates the height of the sample by the calculation unit based on the first height and the second height. Thickness is calculated.

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