JP6004251B2 - Shape measuring method and shape measuring apparatus - Google Patents

Description

  The present invention relates to a shape measuring method and a shape measuring apparatus for measuring the shape of a fine structure such as a diffractive lens having a level difference of several to several tens [μm] or a blazed shape.

  This type of shape measurement method measures a paper-like or sheet-like device created by a method using a printing technique called so-called printable electronics. Although the shape of the object to be measured is various, for example, in a backplane of a display element typified by electronic paper, unevenness due to minute partitions and wirings of several to several tens [μm] is formed on a thin sheet. Other than this, for example, an optical element in which a sawtooth cross-sectional shape called a blazed shape having a pitch of about 5 to 100 [μm] and a step of about 0.5 to 2 [μm] is arranged in an array on a plane. And an optical element having a blazed or rectangular diffraction pattern in which the base surface is formed as a convex surface, a concave surface or a free-form surface.

  As a method for measuring the shape of these objects to be measured, there are a method using a Newton ring, a method using a three-dimensional measuring device, a method using a confocal microscope, and the like. Among these, the method using Newton rings is a method using interference. A method using a three-dimensional measuring device detects a three-dimensional coordinate value obtained by performing point measurement or line measurement on the surface of an object to be measured with a stylus portion of a sphere called a probe. Then, these detected values are processed to measure a three-dimensional shape. As a method using a confocal microscope, one described in Patent Document 1 is known. The level difference measuring apparatus disclosed in Patent Document 1 uses the principle of a confocal microscope, scans a surface to be measured while irradiating a laser beam, and detects a focal position while measuring the light intensity of reflected light from the surface to be measured. Thus, the shape of the surface to be measured is continuously measured.

  However, in the method using the Newton ring, since it is a surface measurement in which the objects to be measured are fixed to the measurement installation table one by one, it takes measurement time. In the level difference measuring apparatus of Patent Document 1 using the confocal microscope, precise scanning in the optical axis direction is required to obtain the light intensity of the reflected light from the surface to be measured, which takes a long measurement time. . Moreover, in the level difference measuring apparatus of Patent Document 1 using the confocal microscope, the laser beam is focused to irradiate the object to be measured, so that the focal part is heated and depending on the material of the object to be measured, the object to be measured is heated. There was a risk of damage. Further, in the method using the Newton ring, if the object to be measured has a curvature or a step on the base surface, the ring-shaped interference fringes are disturbed and the shape of the object to be measured cannot be measured accurately. In the method using the three-dimensional measuring instrument, the probe cannot scan along a groove narrower than the diameter of the sphere of the probe, and a finely shaped structure such as a groove narrower than the diameter of the sphere of the probe can be accurately obtained. It cannot be measured. Even when the object to be measured is a soft material such as a film, the object to be measured itself is deformed by the contact pressure of the probe, so that it cannot be measured accurately.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a shape measuring method capable of accurately measuring the shape of a finely shaped structure in a short time and without damaging the object to be measured. And providing a shape measuring device.

  In order to achieve the above object, the invention according to claim 1 is a shape measuring method for measuring a shape of an object to be measured, which is a medium having a Faraday effect and is in contact with at least the surface to be measured of the object to be measured, and the surface to be measured. Covering the surface of the medium opposite to the surface side in contact with the base surface of the surface to be measured in parallel, generating a Faraday effect by generating a magnetic field of a certain intensity on the medium, and at least the object to be measured When the parallel light of a specific polarization direction is irradiated in the thickness direction of the medium covering the surface to be measured and transmitted through the medium having translucency by the Faraday effect, the interface between the medium and the surface to be measured The polarization direction of the parallel light that changes according to the thickness between the surface and the surface in contact with the medium is measured, and based on the polarization direction of the transmitted light of the medium and the predetermined polarization direction of the parallel light incident on the medium as a measurement result Measure the thickness of the medium And it is characterized in that for measuring the shape of the object to be measured based on the thickness of the medium.

  According to the present invention, the Faraday effect is a phenomenon in which the polarization direction rotates when light travels in the magnetic field direction in a magnetic field, and when linearly polarized light is incident on a medium having this effect, the polarization direction depends on the thickness of the medium or It rotates in proportion to the strength of the magnetic field. The intensity of the magnetic field generated in the medium having such a Faraday effect is made constant, and the medium is irradiated with parallel light in a specific polarization direction, and the medium having translucency is transmitted by the Faraday effect. The polarization direction of the parallel light that changes in accordance with the thickness between the interface of the medium and the surface in contact with the surface to be measured when passing through the medium is measured. Due to the Faraday effect, the thickness of the medium in the light irradiation direction can be measured based on the polarization direction of the transmitted light of the medium as a measurement result and the predetermined polarization direction of the parallel light incident on the medium. Measure the medium with this Faraday effect so that it touches at least the surface to be measured of the object to be measured and the interface of the medium opposite to the surface that contacts the surface to be measured is parallel to the base surface of the surface to be measured. Cover the surface. Then, the concave surface, convex surface, and free-form surface of the surface to be measured of the object to be measured are inverted and formed on the medium. The thickness of the medium can be measured by measuring the thickness between the medium interface and the surface in contact with the surface to be measured. The shape of the object to be measured can be measured based on the measurement result. Since the probe is not brought into contact with the light and the light is not collected as in the conventional case, the object to be measured is not deformed or the object to be measured is not heated. Since it is not necessary to irradiate the surface to be measured of the object to be measured and acquire a large number of slice images in the optical axis direction, the measurement time can be shortened. Therefore, it is possible to obtain a unique effect that the shape of the fine structure can be accurately measured in a short time and without giving damage to the object to be measured.

It is a figure explaining the example using the medium which has a Faraday effect. It is a figure explaining the example using the medium which has a cotton mouton effect. It is an example of the fine-shaped structure of the measuring object in this embodiment. It is an example of the fine-shaped structure of the measuring object in this embodiment. It is an example of the fine-shaped structure of the measuring object in this embodiment. It is an example of the fine-shaped structure of the measuring object in this embodiment. It is a schematic sectional drawing which shows the partial structure of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the partial structure of the shape measuring apparatus which concerns on this embodiment. It is another example of the fine-shaped structure of the measuring object in this embodiment. It is a schematic sectional drawing which shows the partial structure of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the partial structure of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification 1 of the shape measuring apparatus which concerns on this embodiment. (A) A perspective view of a fine shape structure to be measured, and (b) to (d) are diagrams for explaining an example of a measurement image. It is a schematic sectional drawing which shows the modification 2 of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification 3 of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification 4 of the shape measuring apparatus which concerns on this embodiment. It is a schematic sectional drawing which shows the modification 5 of the shape measuring apparatus which concerns on this embodiment.

  First, the Faraday effect and cotton mouton effect used by the present invention will be described. The Faraday effect is a phenomenon in which the plane of polarization rotates when light travels in the magnetic field direction in a magnetic field. When linearly polarized light enters a medium having this effect, the direction of polarization rotates in proportion to the thickness of the medium or the strength of the magnetic field. An example of a medium having a Faraday effect is a magnetic fluid. This ferrofluid is usually a dark brown and opaque liquid, but it can transmit light by forming a thin film with a thickness of several to several tens [μm] by sandwiching it between two parallel plates. And is known to have a magneto-optic effect. Conventionally, a phenomenon observed when light is transmitted through a transparent magnetic material or reflected by a magnetic material, that is, an effect similar to the Faraday effect can be obtained with a magnetic fluid.

  For example, even if the polarization state of the incident light 11 in FIG. 1 is random, the incident light 11 becomes linearly polarized light 13 when transmitted through the polarizer 12. When the direction of the magnetic field 14 and the traveling direction of the light are parallel, the direction of the polarization 16 of the light is rotated by the medium 15 having the Faraday effect. When the polarization direction at this time coincides with the direction of the analyzer 17, the outgoing light 18 passes through the analyzer 17 and exits. Thus, the linearly polarized light changes its polarization direction in proportion to the thickness of the medium having the Faraday effect or the strength of the magnetic field. The medium 15 may be liquid, gel, or powder.

The cotton-Mouton effect is a phenomenon of birefringence that occurs in a sample to which a magnetic field is applied. For example, even if the polarization state of the incident light 21 in FIG. 2 is random, the incident light 21 from the light source is linearly polarized by the polarizer 22 having a polarization plane inclined by α ° from the direction in which the magnetic field is applied. The light enters the magnetized magnetic body 23. The linearly polarized light 24 is divided into perpendicular linearly polarized light and parallel linearly polarized light by the magnetic field 26 in the medium 25, and a phase difference is generated between the two. The outgoing light 27 is linearly polarized when the phase difference is 0, and is elliptically polarized when there is a phase difference. When the phase difference is 90 °, the synthesized light is circularly polarized. When the analyzer 28 having a polarization plane rotated by 90 ° with respect to the polarization plane of the polarizer 22 is transmitted, the output light intensity I of the transmitted light 29 at this time is the polarization of the incident light with respect to the incident light intensity I ₀ . It is known that I = I ₀ sin ² (2α) sin ² (θ / 2) where α is the angle of the surface and θ is the phase difference. That is, when θ = 0, no light is transmitted, and when θ = 90 °, the maximum transmission amount is obtained.

Next, the measurement principle of the method for measuring the shape of the fine structure when the Faraday effect is used will be described.
First, an example of a finely shaped structure that is a measurement target in the present embodiment will be described. 3-6 is an example of the fine-shaped structure of the measuring object in this embodiment. As shown in FIG. 3 (a), which is a perspective view, and in FIG. 3 (b), which is a cross-sectional view taken along line AA ′ of FIG. 3 (a), the device 40 as a fine-shaped structure is made of PET (Polyethylene Terephthalate). ), A resin film such as polyimide, various papers, glass, silicon, metal such as iron or aluminum, and the like are used as the substrate 41, and the periodic protrusions 42 are provided on the substrate 41. As shown in FIG. 4A, which is a perspective view, and FIG. 4B, which is a cross-sectional view taken along the line AA ′ in FIG. 4A, the device 50 has a groove 52 in the substrate 51. . Further, as shown in FIG. 5A, which is a perspective view, and in FIG. 5B, which is a cross-sectional view taken along line AA ′ of FIG. 5A, the device 60 is a device having a fine blazed structure. is there. Furthermore, the device 70 shown in FIG. 6 which is a perspective view has a plurality of lenses 72 arranged in an array on a substrate 71. The device may be a combination of these devices.

  FIG. 7 is a schematic cross-sectional view showing the basic configuration of the shape measuring apparatus according to the present embodiment. The device to be measured here has the blaze structure shown in FIG. Specifically, it is a thin blazed optical sheet, and a sheet-like optical device having a surface shape such as a fine step of a sawtooth cross section, for example, a blazed diffraction lens is formed on a thin sheet surface. When measuring the blazed surface of such a measured object 101, the measured object 101 is placed in a container 102 hollowed so that light can pass through, and a medium having a Faraday effect on the blazed surface side of the measured object 101 is used. The magnetic fluid 103 is dropped. All the blaze surfaces of the device under test 101 are covered with the magnetic fluid 103, and the device under test 101 is immersed in the magnetic fluid 103. The magnetic fluid 103 is balanced with gravity to form a horizontal interface. If possible, the refractive index of the magnetic fluid is preferably close to the refractive index of the object to be measured in order to prevent unnecessary reflection and refraction. Then, by generating a magnetic field using the magnetic field generation means 104, for example, an electromagnet, and applying a magnetic field to the magnetic fluid 103, the polarization direction of the light transmitted through the object 101 is rotated by the Faraday effect. As described above, the Faraday effect is proportional to the strength of the magnetic field or the thickness of the medium having the Faraday effect. Therefore, when light passes through the magnetic fluid, the transmission distance differs depending on the shape of the blazed surface of the object to be measured. The state is different.

  If a polarizer and an analyzer are inserted before and after the transmitted light, this different polarization state can be detected by rotating the analyzer, and blaze depth information can be obtained. In addition to the above configuration, in the optical system, the container is transparent or a reflecting surface. Further, as the magnetic field generating means 104, a permanent magnet may be used instead of an electromagnet. Further, the medium having the Faraday effect such as magnetic fluid or magnetorheological fluid may be of any type or property. The same effect can be obtained by rotating the polarizer instead of rotating the analyzer. Furthermore, even if neither the polarizer nor the analyzer is rotated, the same effect can be obtained and measured by changing the intensity of the magnetic field.

  Here, the magnetorheological fluid and the magnetic fluid will be described. Magnetorheological fluid changes its viscoelasticity in response to a magnetic field, and its appearance changes from a liquid to a solid. The magnetic fluid is attracted in response to the magnetic field and generates pressure. The magnetorheological fluid is obtained by dispersing a magnetic material in a solvent. As the solvent, silicon oil, hydrocarbon oil, water and the like are often used. Pure iron or magnetite is used as the magnetic material, and a surfactant is added to improve dispersibility. On the other hand, the magnetic fluid is similar in structure to the magnetorheological fluid, but the magnetic substance of the magnetorheological fluid has a particle diameter of several to several tens [μm], whereas the magnetic substance of the magnetic fluid has a particle diameter of several to several tens of μm. The size is different from [nm]. Examples of the magnetorheological fluid include MRF-122-2ED, MRF-132AD, MRF-241ES, and MRF-336AG manufactured by LORD, USA. Examples of magnetic fluids include APG810, APG820, REN1020, and REN1600 from Ferrotech, Japan.

  As described above, magnetic fluid has the property of being attracted to a magnetic field. Although the Faraday effect is observed even in a weak magnetic field, when a strong magnetic field is applied, the magnetic fluid is attracted to the magnetic field, and the interface of the magnetic fluid may not be horizontal. Therefore, as shown in FIG. 8, the interface of the magnetic fluid can be kept horizontal by covering the DUT 101 with a transparent plate member 105.

  Another device to be measured here is an object to be measured in which a fine shape such as a diffractive surface is formed on a convex lens or a concave lens and the base surface is a curved surface. The device shown in FIG. 9 is a DUT 101 having a fine shape such as a diffractive surface formed on a convex lens and a curved base surface. By immersing such an object to be measured in the magnetic fluid 103 as shown in FIG. 10, it is possible to obtain a change in the polarization direction that matches the shape of the magnetic fluid 103 by the Faraday effect. In addition, when the interface of the magnetic fluid 103 is disturbed by the influence of a magnetic field, a transparent member 111 having a curved surface close to the curve of the base surface of the device under test 101 is used as the base of the device under test 101 as shown in FIG. By installing it so as to face the surface, a stable magnetic fluid interface can be obtained. In addition, as described above, the magnetic fluid 103 is difficult to transmit light unless the thickness is several to several tens [μm]. However, by attaching the transparent member 111, the thickness of the magnetic fluid 103 on the blazed surface is reduced. Can be reduced.

  FIG. 12 is a schematic sectional view showing a first modification of the shape measuring apparatus according to the present embodiment. 12, the same reference numerals as those in FIG. 7 denote the same components. When measuring an optical element having a surface shape such as a fine step, for example, an object to be measured 101 having an array of blazed surfaces formed on a flat plate, the object to be measured 101 is hollowed out so that light can pass therethrough. A medium having a Faraday effect, such as a magnetorheological fluid or a magnetic fluid, is dropped onto the object to be measured 101 in a container 102. The container 102 may be a transparent container. The fine shape to be measured, here the blazed surface, is immersed in a magnetorheological fluid or a magnetic fluid. In general, a magnetic fluid is smaller in particle shape and has better fluidity than a magnetorheological fluid, so that the following description will mainly describe the magnetic fluid. At this time, the magnetic fluid 103 is balanced with gravity to form a horizontal interface. If possible, it is desirable that the refractive index of the magnetic fluid 103 be equal to or close to the refractive index of the device under test 101 in order to prevent unnecessary refraction and reflection of the measurement light. At this time, a magnetic field is generated by using the magnetic field generating means 104, for example, a permanent magnet or an electromagnet, and a magnetic field is applied to the magnetic fluid. As a result, the polarization direction of the light transmitted through the magnetic fluid is rotated by the Faraday effect. Since the strength of the Faraday effect is proportional to the strength of the magnetic field or the thickness of the medium having the Faraday effect, the thickness of the magnetic fluid varies depending on the shape of the blazed surface of the object to be measured when light passes through the magnetic fluid. , Transmission distance is different, polarization state is different.

  Here, the optical system will be described. In FIG. 12, for example, light emitted from a light source 120 such as a white light source or a laser light source is converted into parallel light by a collimating optical system lens 122 through a pinhole 121 and transmitted through a polarizer 123 to be linearly polarized light. Then, the linearly polarized light is incident on the object to be measured 101 and is transmitted through the medium 103 having the Faraday effect. Since it only needs to pass through the medium having the Faraday effect, it may be from either the direction of the non-measurement object 101 or the magnetic fluid side. The rotation angle of the incident light changes in a predetermined polarization direction at each location on the blazed surface according to the thickness of the magnetic fluid 103. By making this light enter the analyzer 124 as light emitted from the object to be measured 101, light in the same direction as the detection angle of the polarization direction of the analyzer 124 is transmitted. The transmitted light is detected as an image by the light-detecting device 126 by the condensing optical system lens 125. If the photodetector 126 uses a CCD, it can acquire a highly accurate image with low sensitivity unevenness for each pixel, and if a CMOS is used, the cost can be reduced. Further, when the PMT is used, a wide dynamic range can be obtained, so that detection accuracy from dark light to bright light is improved.

  At this time, if the analyzer 124 is rotated around the optical axis, only the light along the polarization direction of the analyzer 24 can be transmitted, so that light in an arbitrary polarization direction can be selectively transmitted. Therefore, by rotating the analyzer 124, the shape of the magnetic fluid 103, that is, the fine shape of the DUT 101 can be measured. Of course, the same effect can be obtained not only by rotating the analyzer 124 but also by rotating the polarizer 123. Further, since the Faraday effect is proportional to the thickness of the medium and the strength of the magnetic field, it is also possible to change the intensity of the light applied to the magnetic fluid 103 by rotating the polarizer 123 and the analyzer 123 instead of rotating the polarizer 123 and the analyzer 123. The shape of the object to be measured can be measured by changing the polarization state.

  The polarization direction detected at each location of the measurement object is analyzed as ternary shape information of the measurement object by an analysis means (not shown) such as a computer. By having this analysis means, it is possible to measure not only the level difference information of the blazed surface but also the period of the arrayed pitch. Even when the measurement object is installed obliquely with respect to the horizontal plane, the alignment error between the liquid level and the measurement object can be corrected.

  Here, an example of the measurement image will be described. Consider a case where a measurement object 131 having a fine shape structure as shown in FIG. 13A, for example, having a blaze surface formed in an array is measured. When the analyzer 124 shown in FIG. 12 is rotated with the initial state shown in FIG. 13B, the position where the transmitted light 133 changes suddenly from the darkest place to the darkest place is a step portion (magnetic fluid) on the blaze surface. It is assumed that the position of the thickest portion matches the position of 132). When the analyzer 124 is slightly rotated from this state, the polarization direction that can be transmitted is rotated, so that the light along the direction of the analyzer 124 is also transmitted in the polarization direction of the transmitted light 133. Therefore, the position of the transmitted light 133 moves to a position slightly shifted from the step portion position 134 corresponding to the step portion 132 as shown in FIG. Further, when the analyzer 124 is rotated, the position of the transmitted light 133 is away from the stepped portion position 134 corresponding to the stepped portion 132 as shown in FIG. By rotating the analyzer 124 in this way, the amount of transmitted light according to the thickness of the magnetic fluid 103 can be obtained. Needless to say, the measurement can be performed not only by rotating the analyzer 124 as described above but also by rotating the polarizer 123 or changing the strength of the magnetic field. In addition, a measurement object having a continuous pitch difference can be used as a product defect inspection method by detecting the presence or absence of a periodic position of transmitted light based on a measurement image.

Next, the principle of the method for measuring the shape of the fine-shaped structure when the Cotton-Mouton effect is used will be described.
As described above, the Cotton-Mouton effect is a phenomenon that occurs when the direction of the magnetic field is orthogonal to the light transmission direction. Since the refractive index of the wave oscillating in the direction perpendicular to the magnetic field direction is different from that of the normal wave perpendicular to the magnetic field direction and the abnormal wave parallel to the magnetic field direction, a phase difference occurs between the two. From the equation of transmitted light intensity I in the above embodiment, if α is set to 45 °, the transmitted light intensity of a liquid having the Cotton-Mouton effect can be maximized. The phase difference θ is 0 °, light is not transmitted, and the maximum transmission amount is 90 °. The relative phase difference changes according to the strength of the magnetic field and the thickness of the medium, for example, the thickness of the magnetic fluid. The thickness of the magnetic fluid can be detected by detecting the distribution of the amount of transmitted light while keeping the magnetic field constant. Here, it is also possible to improve the detection sensitivity of the thickness of the magnetic fluid by changing the strength of the magnetic field.

  FIG. 14 is a schematic sectional view showing a second modification of the shape measuring apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 12 denote the same components. The difference from the shape measuring apparatus of FIG. 12 is that the transmission distance of the magnetic fluid is extended and the sensitivity is improved by using a reflection type. For this purpose, in the shape measuring apparatus of FIG. 14, the beam splitter 141 is used to enter the measured object 101 from the same direction and to emit in the same direction. The light that has passed through the device under test 101 via the magnetic fluid 103 is reflected by the mirror 142 and passes through the device under test 101 and the magnetic fluid 103 again. The transmitted light passes through the beam splitter 141 and is detected as an image by the photodetector 126 via the analyzer 124 and the condensing optical system lens 125. Compared with the shape measuring apparatus of FIG. 12, the distance penetrating the magnetic fluid 103 is doubled, so that the fine shape of the object to be measured can be detected with high sensitivity.

  FIG. 15 is a schematic sectional view showing a third modification of the shape measuring apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 14 denote the same components. The difference from the shape measuring apparatus of FIG. 14 is that the mirror and the container are integrated and a transparent plate member 151 is provided. The bottom surface of the container 102 is preferably a mirror surface, but reflection at the interface may be used with a transparent body having a difference in refractive index. Like the measuring apparatus of FIG. 14, since it is a reflection type, a sensitivity improves. Further, by covering the magnetic fluid 103 with the transparent plate-shaped member 151, the interface of the magnetic fluid 103 is changed by changing the magnetic fluid 103 when the magnetic field is applied or by changing the strength of the magnetic field. The fluctuation can be suppressed and the thickness of the magnetic fluid on the object to be measured can be fixed.

  FIG. 16 is a schematic cross-sectional view showing Modification 4 of the shape measuring apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 14 denote the same components. The difference from the shape measuring apparatus of FIG. 14 is that the transparent container 161 is used to install the object to be measured 101 in the direction in which the blaze surface is facing in the opposite direction, that is, toward the bottom surface of the transparent container 161. This is the point where light enters from. Accordingly, the bottom surface of the transparent container 161 has a function of a plate-like member, and handling from a surface of the object to be measured facing the surface to be measured is possible.

  FIG. 17 is a schematic cross-sectional view showing a fifth modification of the shape measuring apparatus according to the present embodiment. In the figure, the same reference numerals as those in FIG. 16 denote the same components. The difference from the shape measuring apparatus of FIG. 16 is that the object to be measured 101 is scanned with a reduced luminous flux. The light emitted from the light source 120 is polarized by the polygon scanner 171 rotating through the pinhole 121, the collimating optical system 122, the polarizer 123, and the beam splitter 131, and is set to a uniform linear velocity by the scanning optical system lens 172. Thus, the entire area of the device under test 101 is scanned. Thereby, it is possible to accurately measure a wide surface of the object to be measured.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect 1)
In a shape measuring method for measuring the shape of an object to be measured, a medium having a Faraday effect is in contact with at least the surface to be measured of the object to be measured, and the interface of the medium opposite to the surface side in contact with the surface to be measured is the surface to be measured A specific polarization in the thickness direction of the medium covering at least the surface to be measured of the object to be measured is generated by generating a magnetic field with a certain intensity on the medium to generate a Faraday effect. Measures the polarization direction of parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when the light is transmitted through the medium with translucency by the Faraday effect. Then, the thickness of the medium is measured based on the polarization direction of the transmitted light of the measured medium and the predetermined polarization direction of the parallel light incident on the medium, and the shape of the object to be measured is measured based on the thickness of the medium. According to this, as described in the above embodiment, the Faraday effect is a phenomenon in which the polarization direction rotates when light travels in the magnetic field direction in a magnetic field, and when linearly polarized light is incident on a medium having this effect, The direction of polarization rotates in proportion to the thickness of the medium or the strength of the magnetic field. The intensity of the magnetic field generated in the medium having such a Faraday effect is made constant, and the medium is irradiated with parallel light in a specific polarization direction, and the medium having translucency is transmitted by the Faraday effect. The polarization direction of the parallel light that changes in accordance with the thickness between the interface of the medium and the surface in contact with the surface to be measured when passing through the medium is measured. Due to the Faraday effect, the thickness of the medium in the light irradiation direction can be measured based on the polarization direction of the transmitted light of the medium as a measurement result and the predetermined polarization direction of the parallel light incident on the medium. Measure the medium with this Faraday effect so that it touches at least the surface to be measured of the object to be measured and the interface of the medium opposite to the surface that contacts the surface to be measured is parallel to the base surface of the surface to be measured. Cover the surface. Then, the concave surface, convex surface, and free-form surface of the surface to be measured of the object to be measured are inverted and formed on the medium. The thickness of the medium can be measured by measuring the thickness between the medium interface and the surface in contact with the surface to be measured. The shape of the object to be measured can be measured based on the measurement result. Since the probe is not brought into contact with the light and the light is not collected as in the conventional case, the object to be measured is not deformed or the object to be measured is not heated. Since it is not necessary to irradiate the surface to be measured of the object to be measured and acquire a large number of slice images in the optical axis direction, the measurement time can be shortened. Therefore, the shape of the fine structure can be measured at high speed without deforming the object to be measured and without damaging the object to be measured.
(Aspect 2)
In a shape measuring method for measuring the shape of an object to be measured, a medium having a Faraday effect is in contact with at least the surface to be measured of the object to be measured, and the interface of the medium opposite to the surface side in contact with the surface to be measured is the surface to be measured The parallel surface of the object to be measured covers at least the surface to be measured in the thickness direction of the medium, irradiates parallel light with a fixed polarization direction, generates a magnetic field on the medium, and produces a Faraday effect. Polarization of parallel light that varies depending on the thickness between the interface of the medium and the surface in contact with the surface to be measured when the intensity of the magnetic field is changed and the medium having translucency is transmitted by the Faraday effect. The direction is measured, the thickness of the medium is measured based on the polarization direction of the transmitted light and the intensity of the magnetic field of the measurement result, and the shape of the object to be measured is measured based on the thickness of the medium. According to this, as described in the above embodiment, a medium having a Faraday effect is generated with a predetermined magnetic field, and the medium is irradiated with parallel light in a specific polarization direction. Make it transparent. The polarization direction of parallel light that changes in accordance with the shape of the medium in the thickness direction when transmitted through the medium is measured. Due to the Faraday effect, the thickness of the medium in the light irradiation direction can be measured based on the polarization direction of the transmitted light of the medium as a measurement result and the value of the magnetic field intensity. Measure the medium with this Faraday effect so that it touches at least the surface to be measured of the object to be measured and the interface of the medium opposite to the surface that contacts the surface to be measured is parallel to the base surface of the surface to be measured. Cover the surface. Then, the concave surface, convex surface, and free-form surface of the surface to be measured of the object to be measured are inverted and formed on the medium. The thickness of the medium can be measured by measuring the thickness between the medium interface and the surface in contact with the surface to be measured. The shape of the object to be measured can be measured based on the measurement result. Therefore, the shape of the fine structure can be measured at high speed without deforming the object to be measured and without damaging the object to be measured.
(Aspect 3)
In the shape measuring method for measuring the shape of an object to be measured, a medium having a cotton-Mouton effect is in contact with at least the surface to be measured of the object to be measured, and the interface of the medium opposite to the surface side in contact with the surface to be measured is covered. Cover the measurement surface so that it is parallel to the base surface, and generate a cotton Mouton effect by generating a magnetic field of a certain intensity in the medium, in the thickness direction of the medium covering at least the measurement surface of the measurement object, Parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when irradiated with parallel light in a predetermined polarization direction and transmitted through a light-transmitting medium due to the Cotton-Mouton effect The thickness of the medium is measured based on the measured amount of transmitted light and the predetermined polarization direction of the parallel light incident on the medium, and the shape of the object to be measured is determined based on the thickness of the medium. taking measurement. According to this, as described in the above-described embodiment, the intensity of the magnetic field generated in the medium having the cotton-Mouton effect is kept constant, and the medium is irradiated with parallel light in a specific polarization direction. Transmits light media. The amount of parallel light that changes in accordance with the shape of the medium in the thickness direction when passing through the medium is measured. By the Cotton-Mouton effect, the thickness of the medium in the light irradiation direction can be measured based on the amount of transmitted light of the medium as a measurement result and the predetermined polarization direction of the parallel light incident on the medium. Measure the medium with this Faraday effect so that it touches at least the surface to be measured of the object to be measured and the interface of the medium opposite to the surface that contacts the surface to be measured is parallel to the base surface of the surface to be measured. Cover the surface. Then, the concave surface, convex surface, and free-form surface of the surface to be measured of the object to be measured are inverted and formed on the medium. The thickness of the medium can be measured by measuring the thickness between the medium interface and the surface in contact with the surface to be measured. The shape of the object to be measured can be measured based on the measurement result. Therefore, the shape of the fine structure can be measured at high speed without deforming the object to be measured and without damaging the object to be measured.
(Aspect 4)
In the shape measuring method for measuring the shape of an object to be measured, a medium having a cotton-Mouton effect is in contact with at least the surface to be measured of the object to be measured, and the interface of the medium opposite to the surface side in contact with the surface to be measured is covered. Cover the measurement surface so that it is parallel to the base surface, irradiate parallel light with a certain polarization direction in the thickness direction of the medium covering at least the measurement surface of the object to be measured, and generate a magnetic field on the medium to create cotton. Depending on the thickness between the interface of the medium and the surface to be measured when the Mouton effect is generated and the intensity of the magnetic field is changed and the light transmission through the cotton Mouton effect is transmitted. The light quantity of the changing parallel light is measured, the thickness of the medium is measured based on the measured light quantity of the transmitted light and the intensity of the magnetic field, and the shape of the object to be measured is measured based on the thickness of the medium. According to this, as described in the above embodiment, a predetermined magnetic field is generated on a medium having the cotton-Mouton effect, and the medium is irradiated with parallel light in a specific polarization direction. Permeate the medium you have. The amount of parallel light that changes in accordance with the shape of the medium in the thickness direction when passing through the medium is measured. Due to the Cotton Mouton effect, the thickness of the medium in the direction of light irradiation can be measured based on the amount of transmitted light and the value of the magnetic field intensity of the measured medium. Measure the medium with this Faraday effect so that it touches at least the surface to be measured of the object to be measured and the interface of the medium opposite to the surface that contacts the surface to be measured is parallel to the base surface of the surface to be measured. Cover the surface. Then, the concave surface, convex surface, and free-form surface of the surface to be measured of the object to be measured are inverted and formed on the medium. The thickness of the medium can be measured by measuring the thickness between the medium interface and the surface in contact with the surface to be measured. The shape of the object to be measured can be measured based on the measurement result. Therefore, the shape of the fine structure can be measured at high speed without deforming the object to be measured and without damaging the object to be measured.
(Aspect 5)
In any one of (Aspect 1) to (Aspect 4), the parallel light that has transmitted through the medium and then transmitted through the object to be measured is regularly reflected and transmitted again through the object to be measured, and then transmits again through the medium. According to this, as described in Modifications 2 and 3 of the above-described embodiment, the distance through which the medium is transmitted twice is doubled, and the thickness of the medium can be detected with high sensitivity.
(Aspect 6)
A light source, a collimating optical system for collimating light from the light source, and a medium having a Faraday effect, which is in contact with at least the surface to be measured of the object to be measured and on the opposite side of the surface that is in contact with the surface to be measured Any object that covers the surface to be measured so that the interface is parallel to the base surface of the surface to be measured, and any parallel light incident in the thickness direction of the medium that covers at least the surface to be measured of the object to be measured A polarizer that linearly polarizes in the polarization direction, a magnetic field generating means that generates a magnetic field of a predetermined intensity on the medium, an analyzer that transmits only parallel light in a specific polarization direction, and parallel light that has passed through the analyzer A polarization direction measuring means for measuring the polarization direction of the light, and generating a Faraday effect by generating a magnetic field of a constant intensity on the medium, and transmitting light by the Faraday effect while relatively rotating the polarization direction of the polarizer or analyzer. Transparent media Then, the polarization direction measuring means measures the polarization direction of the parallel light transmitted through the analyzer that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured. The thickness of the medium is measured based on the polarization direction and a predetermined polarization direction of the parallel light incident on the medium, or the intensity of the magnetic field is changed, and when the medium is transmitted through the translucent medium by the Faraday effect, The polarization direction of the parallel light that changes according to the shape in the thickness direction is measured by the polarization direction measuring means, and the thickness of the medium is measured based on the polarization direction of the transmitted light and the intensity of the magnetic field of the measurement result. And a shape measuring means for measuring the shape of the object to be measured based on the thickness. According to this, as described in the above embodiment, the parallel light arbitrarily polarized in the polarization direction by the collimating optical system lens 122 is irradiated in the thickness direction of the medium, the magnetic field strength is kept constant, and the polarizer 123 and While rotating the polarization direction of the parallel light relative to the analyzer 124 or changing the intensity of the magnetic field by the magnetic field generation means 104 while keeping the relative polarization direction of the parallel light constant, the light of the polarization direction measurement means The polarization direction of the parallel light transmitted through the medium is measured by the detector 126. The shape of the medium can be measured based on the polarization direction of the parallel light and the relative polarization direction or magnetic field strength of the measurement result. Thereby, the shape of the object to be measured can be measured based on the measured shape of the medium .
( Aspect 7)
And Oite to (embodiment 6), the relative angle between the polarization angle of the polarization angle and the analyzer polarizer 90 degrees. According to this, as described in the above embodiment, the thickness of the medium can be detected with high sensitivity.
(Aspect 8)
In (Aspect 6) or ( Aspect 7) , the medium is a magnetic fluid or a magnetorheological fluid. According to this, as described in the above embodiment, the magnetic fluid or magnetorheological fluid produces magneto-optical characteristics such as the Faraday effect and the cotton-Mouton effect even if the generated magnetic field is weak. Accordingly, the shape of the object to be measured can be measured based on the measured shape of the medium even with a weak magnetic field.
(Aspect 9)
In any one of (Aspect 4) to (Aspect 8) , it has a cross-sectional shape substantially equal to the base cross-sectional shape of the object to be measured on the measurement surface side, and is in contact with the interface of the medium on the measurement surface side of the object to be measured. Provide a transparent member that covers the medium. According to this, as described in the above embodiment, the interface of the medium is stabilized, the thickness of the medium can be reduced, light is easily transmitted, and the thickness of the medium is detected with high sensitivity. be able to.

DESCRIPTION OF SYMBOLS 11 Incident light 12 Polarizer 13 Linearly polarized light 14 Magnetic field 15 Medium 16 Polarized light 17 Analyzer 18 Output light 21 Incident light 22 Polarizer 23 Magnetic body 24 Linearly polarized light 25 Medium 26 Magnetic field 27 Output light 28 Analyzer 29 Transmitted light 40 Device 41 Substrate 42 convex portion 50 device 51 substrate 52 groove portion 60 device 70 device 71 substrate 72 lens 101 object 102 container 103 medium 104 magnetic field generation means 105 plate member 111 transparent member 120 light source 121 pinhole 122 collimating optical system lens 123 polarizer 124 Analyzer 125 Condensing optical system lens 126 Photo detector 131 Object to be measured 132 Stepped portion 133 Transmitted light 134 Stepped portion equivalent position 141 Beam splitter 142 Mirror 151 Plate member 161 Transparent container 171 Polygon scanner 172 Scanning optical system lens

JP-A-10-026515

Claims (9)

In the shape measuring method for measuring the shape of the object to be measured,
A medium having a Faraday effect, covering at least the surface to be measured of the object to be measured and covering the interface of the medium opposite to the surface side in contact with the surface to be measured in parallel with the base surface of the surface to be measured,
Generating a Faraday effect by generating a magnetic field of a certain intensity on the medium, irradiating parallel light of a specific polarization direction in the thickness direction of the medium covering at least the surface to be measured of the object to be measured;
Measure the polarization direction of parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when transmitted through the medium having translucency by the Faraday effect. Measuring a thickness of the medium based on a polarization direction of transmitted light of the medium and a predetermined polarization direction of parallel light incident on the medium, and measuring a shape of the object to be measured based on the thickness of the medium. A characteristic shape measurement method. In the shape measuring method for measuring the shape of the object to be measured,
A medium having a Faraday effect, covering at least the surface to be measured of the object to be measured and covering the interface of the medium opposite to the surface side in contact with the surface to be measured in parallel with the base surface of the surface to be measured,
Irradiate parallel light with a constant polarization direction in the thickness direction of the medium covering at least the measurement surface of the measurement object,
Generating a magnetic field in the medium to produce a Faraday effect, and changing the strength of the magnetic field;
Measure the polarization direction of parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when transmitted through the medium having translucency by the Faraday effect. A shape measuring method, comprising: measuring a thickness of the medium based on a polarization direction of transmitted light of the medium and a value of intensity of the magnetic field; and measuring a shape of an object to be measured based on the thickness of the medium. In the shape measuring method for measuring the shape of the object to be measured,
A medium that has the Cotton-Mouton effect and covers at least the surface to be measured of the object to be measured, and covers the surface of the medium opposite to the surface that contacts the surface to be measured in parallel with the base surface of the surface to be measured. ,
A magnetic Mouton effect is generated by generating a magnetic field of a certain intensity in the medium,
Irradiate parallel light in a predetermined polarization direction in the thickness direction of the medium covering at least the measurement surface of the measurement object;
Measures the amount of parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when the medium having translucency is transmitted by the Cotton Mouton effect, and the measurement result Measuring the thickness of the medium based on the amount of transmitted light of the medium and a predetermined polarization direction of parallel light incident on the medium, and measuring the shape of the object to be measured based on the thickness of the medium. A characteristic shape measurement method. In the shape measuring method for measuring the shape of the object to be measured,
A medium that has the Cotton-Mouton effect and covers at least the surface to be measured of the object to be measured, and covers the surface of the medium opposite to the surface that contacts the surface to be measured in parallel with the base surface of the surface to be measured. ,
Irradiate parallel light with a constant polarization direction in the thickness direction of the medium covering at least the measurement surface of the measurement object,
Generating a magnetic field in the medium to produce a Cotton Mouton effect, and changing the strength of the magnetic field;
Measures the amount of parallel light that changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured when the medium having translucency is transmitted by the Cotton Mouton effect, and the measurement result A shape measuring method comprising: measuring the thickness of the medium based on the amount of transmitted light of the medium and the intensity of the magnetic field, and measuring the shape of the object to be measured based on the thickness of the medium. In the shape measuring method according to any one of claims 1 to 4,
A shape measuring method, wherein the parallel light that has passed through the medium after passing through the medium is specularly reflected, transmitted again through the object to be measured, and then transmitted through the medium again. A light source;
A collimating optical system for collimating light from the light source;
A medium having a Faraday effect, in which a surface to be measured is in contact with at least a surface to be measured of the object to be measured and the interface of the medium opposite to the surface in contact with the surface to be measured is parallel to the base surface of the surface to be measured An object to be measured,
A polarizer that arbitrarily converts parallel light incident in the thickness direction of the medium covering at least the surface to be measured of the object to be measured into linearly polarized light in the polarization direction;
Magnetic field generating means for generating a magnetic field of a predetermined intensity on the medium;
An analyzer that transmits only parallel light in a specific polarization direction;
Polarization direction measuring means for measuring the polarization direction of the parallel light transmitted through the analyzer;
A Faraday effect is generated by generating a magnetic field of a certain intensity in the medium, and the medium having transparency is transmitted by the Faraday effect while relatively rotating the polarization direction of the polarizer or the analyzer. The polarization direction measuring means measures the polarization direction of the parallel light that has passed through the analyzer and changes according to the thickness between the interface of the medium and the surface in contact with the surface to be measured. The thickness of the medium is measured based on the polarization direction of the transmitted light and the predetermined polarization direction of the parallel light incident on the medium, or the intensity of the magnetic field is changed, and the Faraday effect has translucency. The polarization direction of the parallel light that changes according to the shape in the thickness direction of the medium when transmitted through the medium is measured by the polarization direction measuring means, and the polarization direction of the transmitted light of the medium as a measurement result The thickness of the medium is measured based on the value of the intensity of the magnetic field, the shape measuring apparatus characterized by having a shape measuring means for measuring the shape of the object to be measured based on the thickness of the medium. In the shape measuring apparatus 請 Motomeko 6 Symbol mounting,
A shape measuring apparatus, wherein a relative angle between a polarization angle of the polarizer and a polarization angle of the analyzer is 90 degrees. In the shape measuring device according to claim 6 or 7 ,
The shape measuring apparatus, wherein the medium is a magnetic fluid or a magnetorheological fluid. In the shape measuring apparatus according to any one of claims 4-8,
Providing a transparent member having a cross-sectional shape substantially equal to a base cross-sectional shape of the measurement object on the measurement surface side and covering the medium in contact with the interface of the medium on the measurement object side of the measurement object; A shape measuring device.

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