Refractive index distribution measurement device, film thickness distribution measurement device, refractive index distribution measurement method, and film thickness distribution measurement method

Abstract

A measurement device (1A) is provided with a conveyance unit (10), a light intensity acquisition unit (20), and a calculation unit (30). The transport unit (10) transports a polymer film in a transport direction (D1). The light intensity acquisition unit (20) irradiates a plurality of light spots arranged in a direction intersecting the conveyance direction (D1) in the polymer film (B) being conveyed with light, and acquires the light intensity of reflected light from the plurality of light spots irradiated with light. A calculation unit (30) calculates the reflectance at each of the plurality of light spots from the light intensity of the reflected light acquired by the light intensity acquisition unit (20), and determines the refractive index distribution of the polymer film (B) on the basis of the reflectance.

Description

Technical Field

[0001] The present invention relates to a refractive index distribution measuring device, a film thickness distribution measuring device, a refractive index distribution measuring method, and a film thickness distribution measuring method. Background Art

[0002] Patent Documents 1 and 2 disclose a film thickness measuring device having a spectroscopic interference method. Patent Document 1 exemplifies a method of using a curve fitting method to obtain the period of intensity of interference light, and calculating the film thickness based on the period and the refractive index of the object. Patent Document 2 exemplifies a method of using a fast Fourier transform (FFT) to obtain the period of intensity of interference light, and calculating the film thickness based on the period and the refractive index of the object.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-141176

[0006] Patent Document 2: International Patent Publication No. 2011 / 045967 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When manufacturing a polymer film, the material of the polymer film is extended in the direction intersecting the conveying direction during transportation and formed into a film shape. As a result, the refractive index of the stretched polymer film becomes a deviation in the direction intersecting the conveying direction. For example, the refractive index of the peripheral portion in the direction intersecting the conveying direction of the polymer film is sometimes different from the refractive index of the central portion in the direction of the polymer film. Such a phenomenon is called a warping phenomenon. The deviation of the refractive index in the direction intersecting the conveying direction of the polymer film is associated with the deviation of the characteristics of the polymer film, and in addition, it becomes the cause of measurement error in the measurement of film thickness, etc. Therefore, it is desirable to measure the deviation of the refractive index in the direction intersecting the conveying direction of the polymer film during transportation.

[0009] The object of the present invention is to provide a refractive index distribution measuring device, a film thickness distribution measuring device, a refractive index distribution measuring method, and a film thickness distribution measuring method, which can measure the deviation of the refractive index in a direction intersecting the conveying direction of the polymer film during the conveying of the polymer film.

[0010] Technical means of solving problems

[0011] [1] A refractive index distribution measuring device according to one embodiment of the present invention includes a conveying unit, a light intensity acquisition unit, and a computing unit. The conveying unit conveys a polymer film in a first direction. The light intensity acquisition unit irradiates light to a plurality of light spots arranged in a second direction intersecting the first direction in the polymer film being conveyed, and acquires the light intensity of reflected light from the plurality of light spots irradiated with light. The computing unit calculates the reflectivity of each of the plurality of light spots from the light intensity of the reflected light acquired in the light intensity acquisition unit, and obtains the refractive index distribution of the polymer film in the second direction based on the reflectivity.

[0012] [2] A refractive index distribution measurement method according to one embodiment of the present invention comprises: a step of starting to transport a polymer film in a first direction; a step of irradiating light onto a plurality of light spots arranged in a second direction intersecting the first direction in the polymer film being transported, and obtaining light intensities of reflected light from the plurality of light spots irradiated with light; and a step of calculating the reflectivity of each of the plurality of light spots based on the light intensities of the reflected light obtained in the obtaining step, and obtaining the refractive index distribution of the polymer film in the second direction based on the reflectivity.

[0013] When an object receives light and reflects the light, its reflectivity depends on the refractive index of the object. In the above-mentioned device and method, light is irradiated on a polymer film being transported, and the reflectivity is calculated from the light intensity of the reflected light, and the refractive index of the polymer film is obtained based on the reflectivity. Therefore, the refractive index of the polymer film being transported can be measured. Furthermore, in the above-mentioned device and method, such refractive index measurement is performed on a plurality of light spots arranged in a direction intersecting with the transport direction. Thus, the deviation of the refractive index in a direction intersecting with the transport direction of the polymer film can be measured in the middle of transporting the polymer film.

[0014] [3] In the refractive index distribution measuring device of the above-mentioned [1], the calculation unit may also calculate the reflectivity at each of the multiple light points based on the ratio of the light intensity of the reflected light from each of the multiple light points to the reference light intensity. The reference light intensity is obtained by irradiating light from the light intensity acquisition unit to a reference reflection surface of known reflectivity and obtaining the light intensity of the reflected light from the reference reflection surface in the light intensity acquisition unit. Similarly, in the refractive index distribution measuring method of the above-mentioned [2], in the step of obtaining the refractive index distribution, the reflectivity at each of the multiple light points may be calculated based on the ratio of the light intensity of the reflected light from each of the multiple light points to the reference light intensity. The reference light intensity is obtained by irradiating light to a reference reflection surface of known reflectivity and obtaining the light intensity of the reflected light from the reference reflection surface. In general, the reflectivity is given by the ratio of the reflected light intensity to the incident light intensity. By irradiating light to the reference reflection surface and obtaining the light intensity of the reflected light from the reference reflection surface, the incident light intensity can be known with good accuracy. Therefore, in this case, for example, even if the light intensity of the light output from the light intensity acquisition unit, that is, the incident light intensity varies with time, the refractive index distribution can be measured with high accuracy.

[0015] [4] In the refractive index distribution measuring device of [3] above, the light intensity acquisition unit may include a reference reflection surface and a mechanism for changing the position of the reference reflection surface. The mechanism changes the position of the reference reflection surface between a position on the optical path of the light emitted from the light intensity acquisition unit and a position away from the optical path. In this case, the reference light intensity can be easily acquired.

[0016] [5] In the refractive index distribution measuring device of [1], [3] or [4] above, the light intensity acquisition unit may also include a plurality of optical units corresponding to the plurality of light spots. The plurality of optical units may also include a light emitting unit for emitting light and a light incident unit for receiving reflected light. [6] Alternatively, in the refractive index distribution measuring device of [1], [3] or [4] above, the light intensity acquisition unit may also include: an optical unit including a light emitting unit for emitting light and a light incident unit for receiving reflected light; and a scanning unit for scanning the optical unit in a direction intersecting the first direction. For example, by using any of these structures, it is possible to irradiate light onto the plurality of light spots and obtain the light intensity of reflected light from the plurality of light spots irradiated with light.

[0017] [7] In the refractive index distribution measuring device of any one of [1], [3] to [6] above, the calculation unit may also calculate the refractive index distribution based on the extinction coefficient of the polymer film. Similarly, in the refractive index distribution measuring method of [2] or [3] above, in the step of calculating the refractive index distribution, the refractive index distribution may also be calculated based on the extinction coefficient of the polymer film. More strictly speaking, the refractive index of an object is related to the extinction coefficient of the object in addition to the reflectivity. Therefore, by calculating the refractive index distribution based on the extinction coefficient of the polymer film, the deviation of the refractive index of the polymer film can be measured with better accuracy.

[0018] [8] In the refractive index distribution measuring device of any one of [1], [3] to [7], or the refractive index distribution measuring method of [2], [3] or [7], the wavelength band of light may be a visible wavelength region, or a wavelength band extending from the visible wavelength region to the near-infrared wavelength region.

[0019] [9] In the refractive index distribution measuring device of any one of [1], [3] to [7], or the refractive index distribution measuring method of [2], [3] or [7], the wavelength band of the light may also include a near-infrared wavelength region. When the wavelength band of the light includes the near-infrared wavelength region, the light can pass through the polymer film even if the polymer film has a color. Therefore, the influence of the color of the polymer film on the measurement result can be reduced.

[0020] A film thickness distribution measuring device according to one embodiment of the present invention comprises the refractive index distribution measuring device of any one of [1], [3] to [9] above. The calculation unit further calculates the film thickness distribution of the polymer film in the second direction based on the light intensity of the reflected light at each of the plurality of light points obtained in the light intensity obtaining unit and the refractive index distribution. A film thickness distribution measuring method according to one embodiment of the present invention comprises the refractive index distribution measuring method of any one of [2], [3], [7] to [9] above, and further comprises: calculating the film thickness distribution of the polymer film in the second direction based on the light intensity of the reflected light at each of the plurality of light points obtained in the step of obtaining the light intensity and the refractive index distribution calculated in the step of calculating the refractive index distribution. According to these film thickness distribution measuring devices and film thickness distribution measuring methods, the film thickness distribution of the polymer film can be measured with good accuracy while taking into account the deviation of the refractive index during the transportation of the polymer film.

[0021] Effects of the Invention

[0022] According to the present invention, a refractive index distribution measuring device, a film thickness distribution measuring device, a refractive index distribution measuring method, and a film thickness distribution measuring method can be provided, which can measure the deviation of the refractive index in a direction intersecting the conveying direction of the polymer film during conveying. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram schematically showing the structure of a measuring device according to one embodiment.

[0024] Figure 2 It is a side view showing an enlarged view of the optical unit.

[0025] Figure 3 It is a top view showing the optical unit and the linear guide.

[0026] Figure 4 Parts (a) and (b) of FIG. 1 are diagrams showing examples of the relationship between reflectance and wavelength.

[0027] Figure 5 Parts (a) and (b) of FIG. 1 are diagrams showing examples of the relationship between reflectance and wavelength.

[0028] Figure 6 This is a diagram for explaining the principle of film thickness measurement.

[0029] Figure 7 Parts (a), (b), and (c) of FIG. 1 are graphs showing the relationship between the intensity of reflected light after interference and the wavelength.

[0030] Figure 8 This is a diagram schematically showing a configuration example of hardware of a computing unit.

[0031] Fig. 9 This is a diagram schematically showing the structure of a control device.

[0032] Fig.10 This is a flowchart showing a method of measuring a refractive index distribution and a film thickness distribution according to one embodiment.

[0033] Fig.11 Parts (a), (b), and (c) are front views showing the structure of the optical unit as a first modification.

[0034] Fig.12 Parts (a), (b), and (c) are front views showing the structure of a light intensity acquisition unit as a second modification example.

[0035] Fig.13 This is a diagram schematically showing the structure of a measuring device according to a third modified example.

[0036] Fig.14 is a top view showing a plurality of optical units.

[0037] Fig.15 Parts (a) and (b) of FIG. 1 are front views showing a state in which a plurality of optical units are arranged in a direction intersecting the conveying direction. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the refractive index distribution measuring device, film thickness distribution measuring device, refractive index distribution measuring method, and film thickness distribution measuring method of the present invention will be described in detail with reference to the accompanying drawings. In the description of the accompanying drawings, the same reference numerals are attached to the same elements, and repeated descriptions are omitted.

[0039] Figure 1 1 is a diagram schematically showing the structure of a measuring device 1A according to an embodiment of the present invention. The measuring device 1A is a device for obtaining the refractive index distribution and film thickness distribution in the direction intersecting the conveying direction of the measured object, i.e., the polymer film B. The polymer film B is, for example, a high-functional film for liquid crystals, a plastic sheet, or an insulator for lithium-ion batteries. The polymer film B of this embodiment may be composed of a single layer (single material), or may have a structure of stacking multiple layers. However, in the case of stacking multiple layers, the refractive index of the other layers except the layer of the measured object is uniform in the direction intersecting the conveying direction and is set to be known.

[0040] The measuring device 1A includes a conveying unit 10, a light intensity acquisition unit 20, a computing unit 30, a control unit 40, an input device 54, and a monitor 55. The conveying unit 10 conveys the polymer film B in a conveying direction D1 (first direction). The conveying unit 10 is, for example, a roller conveyor, and includes a plurality of roller pairs 11 and a driving unit (not shown) such as a motor for rotating and driving the plurality of roller pairs 11. The plurality of roller pairs 11 each include a pair of rollers 11a and 11b having a rotation axis extending in the width direction of the polymer film B. The polymer film B is conveyed by the rollers 11a and 11b rotating in opposite directions to each other while being sandwiched between the rollers 11a and 11b.

[0041] The light intensity acquisition unit 20 irradiates light onto a plurality of light spots arranged in a direction (second direction) intersecting the conveying direction D1, and acquires the light intensity of reflected light from the plurality of light spots irradiated with light. To this end, the light intensity acquisition unit 20 includes an optical unit 21, a light source unit 22, a spectroscopic detection unit 23, light guide members 24 and 25, and a linear guide 26.

[0042] The light source unit 22 generates incoherent (incoherent) light L1. The wavelength band of the light L1 may be a visible wavelength region. In this case, the light source unit 22 is, for example, a lamp-type light source or a white LED that emits white light. The wavelength band of the light L1 may be a wavelength band that extends from the visible wavelength region to the near-infrared wavelength region. The wavelength band of the light L1 may have a substantially flat (wide) spectrum in the infrared wavelength region. In particular, when the wavelength band of the light L1 includes the near-infrared wavelength region, the light L1 may be able to pass through the polymer film B even if the polymer film B has a color scheme. Therefore, the influence of the color scheme of the polymer film B on the measurement results may be reduced. In this case, as the light source unit 22, various light-emitting elements such as an ASE (Amplified Spontaneous Emission) light source, an LED, or an SLD (Super Luminescent Diode) may be applied. Optical components such as white light sources and optical films may also be combined with each other.

[0043] One end of the light guide member 24 is optically coupled to the light source unit 22, and guides the light L1 emitted from the light source unit 22. As the light guide member 24, for example, a light guide or an optical fiber is used. The optical unit 21 is optically coupled to the other end of the light guide member 24, and irradiates the light L1 guided by the light guide member 24 to the polymer film B. The reflected light L2 from the polymer film B is incident on the optical unit 21. The optical unit 21 is arranged at a position opposite to the main surface Ba of the polymer film B. One end of the light guide member 25 is optically coupled to the optical unit 21, and guides the reflected light L2 incident on the optical unit 21. As the light guide member 25, for example, a light guide or an optical fiber is used. The spectroscopic detection unit 23 is optically coupled to the other end of the light guide member 25, and spectrally separates the reflected light L2 guided by the light guide member 25 into each wavelength, and detects the intensity of the light of each wavelength after spectrally separate. The spectroscopic detection unit 23 can be composed of, for example, a combination of a spectroscopic optical element and an imaging element. The spectroscopic optical element is, for example, a prism or a grating element. The imaging element is, for example, a line sensor, an area image sensor, a photomultiplier tube, or a photodiode. The spectroscopic detection unit 23 outputs the detected light intensity as an electrical signal. The light source unit 22 and the spectroscopic detection unit 23 are housed in a housing of the measurement unit 60 together with the computing unit 30 described below.

[0044] Figure 2: is a side view showing an enlarged view of the optical unit 21. The optical unit 21 includes a light emitting portion 211 and a light incident portion 212. The light emitting portion 211 irradiates the light L1 obtained from the light source portion 22 via the light guide member 24 to the light spot SP of the polymer film B. The light emitting portion 211 is configured to include, for example, a focusing lens optically coupled to the other end of the light guide member 24. The light incident portion 212 receives the reflected light L2 generated by reflecting the light L1 at the light spot SP of the polymer film B. The reflected light L2 includes light reflected from the main surface Ba of the polymer film B and light reflected from the surface Bb opposite to the main surface Ba. The light incident portion 212 is configured to include, for example, a focusing lens optically coupled to one end of the light guide member 25. The optical axis of the light emitting portion 211 and the optical axis of the light incident portion 212 may be parallel to each other, or may intersect with each other in the polymer film B. Alternatively, the optical axis of the light emitting portion 211 and the optical axis of the light incident portion 212 may be consistent with each other. The light source unit 22, the light guide member 24 and the light emitting unit 211 constitute a light irradiation unit for irradiating the polymer film B with the light L1. The light incident unit 212, the light guide member 25 and the spectroscopic detection unit 23 constitute a light detection unit for detecting the light intensity of the reflected light L2 from the polymer film B for each wavelength.

[0045] Figure 3 : is a top view showing the optical unit 21 and the linear guide 26. The linear guide 26 is an example of a scanning unit of the present embodiment. The linear guide 26 supports the optical unit 21 and scans the optical unit 21 in the direction D2 intersecting the conveying direction D1. In other words, the linear guide 26 can move the optical unit 21 in one dimension along the direction D2. In one example, the direction D2 is the width direction of the polymer film B and is orthogonal to the conveying direction D1. The linear guide 26 is electrically connected to the control unit 27 and is driven by a drive signal provided from the control unit 27. The control unit 27 controls the linear guide 26 in such a manner that the optical unit 21 moves back and forth between one end edge and the other end edge in the direction D2 of the polymer film B. The linear guide 26 includes, for example, an actuator and a slide table, and is configured so that the slide table holding the optical unit 21 can move back and forth in the direction D2 by the actuator. For example, the actuator of the linear guide 26 is composed of a ball screw having a rotating shaft and a motor such as a servo motor or a pulse motor, and the slide table moves when the ball screw is rotated by the motor. In this way, by scanning the optical unit 21 in the direction D2 while irradiating the light L1 and inputting the reflected light L2, the light L1 can be irradiated to a plurality of light spots SP arranged in a direction (second direction) intersecting the conveying direction D1, and the light intensity of the reflected light L2 from the plurality of light spots SP can be obtained. In the present embodiment, the direction intersecting the conveying direction D1 is the direction of a vector synthesized by the velocity vector of the conveying direction D1 and the scanning vector of the direction D2.

[0046] Refer again Figure 1. The calculation unit 30 calculates the reflectivity at each of the multiple light spots SP from the light intensity of the reflected light L2 obtained in the light intensity acquisition unit 20. The reflectivity is calculated based on the ratio of the light intensity of the reflected light L2 to the reference light intensity. The reference light intensity is typically the light intensity of the light L1. The light intensity of the light L1 is obtained, for example, by irradiating the light L1 to a reference reflection surface whose reflectivity is known, and obtaining the light intensity of the reflected light from the reference reflection surface. In one example, the reference reflection surface is a mirror surface with a reflectivity of almost 100%. Then, based on the reflectivity, the calculation unit 30 calculates the refractive index distribution of the polymer film B in the direction intersecting the conveying direction D1. Here, the refractive index n of a certain medium uses the reflectivity R at the interface between the medium and the surrounding medium, as shown in the following formula (1).

[0047] [Number 1]

[0048]

[0049] The k in the formula is the extinction coefficient inherent to the substance. The extinction coefficient k can be obtained in advance from the composition of the polymer film B. In addition, since the extinction coefficient k is a very small value compared to the reflectivity R, it can also be ignored in the above formula. In this case, the formula (1) can be rewritten as the following formula (2).

[0050] [Number 2]

[0051]

[0052] In the present embodiment, the spectroscopic detection unit 23 detects the light intensity of the reflected light L2 for each wavelength. Figure 4 Part (a) and (b) of Figure 5 Parts (a) and (b) of FIG. 1 are diagrams showing examples of the relationship between reflectivity and wavelength. In these diagrams, the vertical axis represents reflectivity (%) and the horizontal axis represents wavelength (nm). The extinction coefficient k is 0.01. As described above, the reflected light L2 includes light reflected from the main surface Ba of the polymer film B and light reflected from the surface Bb opposite to the main surface Ba. Since the optical path lengths of these lights differ from each other by the thickness of the polymer film B, these lights interfere with each other. Therefore, as shown in these figures, the reflectivity varies periodically according to the wavelength. As the reflectivity R in the above formula (1), for example, the wavelength average value of the varying reflectivity (straight line C in the figure) is used.

[0053] The calculation unit 30 further obtains the film thickness distribution of the polymer film B in the direction intersecting the conveying direction D1 based on the light intensity of the reflected light L2 at each of the plurality of light spots SP acquired by the light intensity acquisition unit 20 and the refractive index distribution. Figure 6This is a diagram for explaining the principle of film thickness measurement, schematically showing a cross section of a polymer film B. At present, when incoherent light L1 is incident on the polymer film B, the reflected light at the main surface Ba of the polymer film B and the reflected light at the surface Bb opposite to the main surface Ba interfere with each other. When the main surface Ba is the light incident surface, the optical path length of the reflected light at the surface Bb becomes longer by the amount of the optical path in the polymer film B relative to the optical path length of the reflected light at the main surface Ba. Therefore, a phase difference corresponding to the film thickness d of the polymer film B is generated between these reflected lights.

[0054] Figure 7 Parts (a), (b), and (c) of FIG. 1 are graphs showing the relationship between the intensity of reflected light after interference and the wavelength. Figure 7 Part (a) shows that the film thickness d of the polymer film B is thinner than that of parts (b) and (c). Figure 7 Part (c) shows that the film thickness d of the polymer film B is thicker than that of parts (a) and (b). Figure 7 As shown in FIG. 1 , the spectrum of the reflected light after interference (reflection spectrum) fluctuates due to interference, but the thicker the film thickness d of the polymer film B, the smaller the interval, i.e., the period, of the wave. That is, the film thickness d of the polymer film B is calculated using the refractive index n of the polymer film B and the wavelength λ of the light L1. 1 and 2 , wavelength λ 1 The wave number and wavelength λ of the reflected light L2 2 The difference Δm in the wave number of the reflected light L2 and the incident angle θ at this time are expressed as the following formula (3).

[0055] [Number 3]

[0056]

[0057] By using the relationship between the reflection spectrum and the film thickness d of the polymer film B as described above, the film thickness d of each of the multiple light spots SP of the polymer film B, that is, the film thickness distribution in the direction intersecting the conveying direction D1, can be obtained. As specific methods, there are fast Fourier transform method and curve fitting method. In the fast Fourier transform method, the reflection spectrum is subjected to fast Fourier transform, and the film thickness d is obtained from its peak frequency. In the curve fitting method, the spectral reflectivity obtained from the measured reflection spectrum, that is, the measured spectral reflectivity, is fitted with the theoretical spectral reflectivity calculated from the theoretical formula. Then, the film thickness d is obtained from the fitted theoretical spectral reflectivity. According to the curve fitting method, even if the film thickness d of the polymer film B is less than 1μm, the film thickness distribution can be measured with good accuracy. The data related to the film thickness distribution of the polymer film B obtained in this way is provided to the control device 40.

[0058] For example, since Figure 4 Based on the data shown in part (a), the refractive index n = 1.4 and the film thickness d = 10 μm are calculated. Figure 4 Based on the data shown in part (b), the refractive index n = 1.5 and the film thickness d = 10 μm are calculated. Figure 5 Based on the data shown in part (a), the refractive index n = 1.4 and the film thickness d = 11 μm are calculated. Figure 5 From the data shown in part (b), the refractive index n=1.5 and the film thickness d=11 μm were calculated.

[0059] The computing unit 30 may be, for example, a personal computer; a smart device such as a smartphone or a tablet terminal; or a computer having a processor such as a cloud server. Figure 8 30 is a diagram schematically showing an example of the hardware configuration of the computing unit 30. Figure 8 As shown, the operation unit 30 can be physically configured as a common computer including a processor (CPU) 31, a main storage device such as ROM 32 and RAM 33, and an auxiliary storage device 34 such as a hard disk. The processor 31 of the computer can realize the functions of the above-mentioned operation unit 30 by reading the program stored in the ROM 32 or the auxiliary storage device 34. Therefore, the program causes the processor 31 of the computer to act as the operation unit 30. The storage device storing the program can also be a non-temporary recording medium. As the recording medium, a recording medium such as a floppy disk, a CD or a DVD, a recording medium such as a ROM, a semiconductor memory or a cloud server, etc. are exemplified.

[0060] Refer again Figure 1 The control device 40 is electrically connected to the conveying unit 10 , the control unit 27 , and the measuring unit 60 . Fig. 9 1 is a diagram schematically showing the structure of the control device 40. The control device 40 includes a transport control unit 41 that controls the operation of the transport unit 10 such as the transport speed, a scan control unit 42 that controls the operation of the control unit 27, and a detection control unit 43 that controls the operation of the light source unit 22 and the spectroscopic detection unit 23. The control device 40 may include any of the hardware structures described in relation to the calculation unit 30.

[0061] The input device 54 is electrically connected to the control device 40. The operator inputs various settings related to the transport control unit 41, the scanning control unit 42, and the detection control unit 43 through the input device 54. The input device 54 can be, for example, a keyboard, a mouse, or a touch panel. The monitor 55 is electrically connected to the control device 40 and displays information related to the refractive index distribution and the film thickness distribution obtained by the calculation unit 30. The monitor 55 can display only information related to the refractive index distribution, or can also display only information related to the film thickness distribution. The monitor 55 can also be a touch screen including a touch panel, that is, the input device 54.

[0062] Fig.101 is a flow chart showing a method for measuring the refractive index distribution and the film thickness distribution of the present embodiment. The measuring method can be implemented using the above-mentioned measuring device 1A. In the measuring method, in step ST1, the polymer film B is started to be transported in the transport direction D1. In step ST2, the irradiation light L1 on the polymer film B being transported and the reflected light L2 from the polymer film B are sequentially detected for a plurality of light spots SP arranged in a direction intersecting the transport direction D1. In step ST3, the reflectivity R of each of the plurality of light spots SP is calculated from the light intensity of the reflected light L2 obtained in step ST2. Then, based on these reflectivities R, the refractive index distribution of the polymer film B in the direction is calculated. In step ST4, based on the light intensity of the reflected light L2 of each of the plurality of light spots SP obtained in step ST2 and the refractive index distribution calculated in step ST3, the film thickness distribution of the polymer film B in the direction is calculated.

[0063] The effects that can be obtained by the measuring device 1A and the measuring method of the present embodiment described above are described. When an object receives light and reflects the light, its reflectivity depends on the refractive index of the object. In the measuring device 1A and the measuring method of the present embodiment, the polymer film B being transported is irradiated with light L1, the reflectivity R is calculated from the light intensity of the self-reflected light L2, and the refractive index n of the polymer film B is obtained based on the reflectivity R. Thus, the refractive index n of the polymer film B being transported can be measured. Furthermore, in the measuring device 1A and the measuring method of the present embodiment, such refractive index measurement is performed on a plurality of light spots SP arranged in a direction intersecting with the transport direction D1. Thus, the deviation of the refractive index n in the direction intersecting with the transport direction D1 of the polymer film B can be measured in the middle of transporting the polymer film B. In addition, according to the measuring device 1A and the measuring method of the present embodiment, the film thickness distribution of the polymer film B can be measured with good accuracy while considering the deviation of the refractive index in the middle of transporting the polymer film B.

[0064] As shown in this embodiment, the light intensity acquisition unit 20 may also include: an optical unit 21 including a light emitting unit 211 for emitting light L1 and a light incident unit 212 for receiving reflected light L2; and a linear guide 26 for scanning the optical unit 21 in a direction D2 intersecting the conveying direction D1. With such a structure, for example, the light L1 can be irradiated to a plurality of light spots SP, and the light intensity of the reflected light L2 from the plurality of light spots SP irradiated with the light L1 can be acquired.

[0065] As described above, the calculation unit 30 may also obtain the refractive index distribution based on the extinction coefficient k of the polymer film B. More strictly speaking, the refractive index of an object is related to the extinction coefficient of the object in addition to the reflectivity. Therefore, by the calculation unit 30 also obtaining the refractive index distribution based on the extinction coefficient k of the polymer film B, the deviation of the refractive index of the polymer film B can be measured with better accuracy.

[0066] [First Modification]

[0067] Fig.11 Parts (a), (b) and (c) are front views showing the structure of the optical unit 21A as a first variant. In these figures, the polymer film B is shown by a cross section cut along a plane perpendicular to the conveying direction D1. The optical unit 21A of this variant has a reflector 28 in addition to the structure of the optical unit 21 of the above-mentioned embodiment. The reflector 28 has a reference reflective surface 28a with a known reflectivity. The reflectivity of the reference reflective surface 28a is, for example, 100%. The optical unit 21A also has a mechanism for changing the position of the reference reflective surface 28a between a position on the optical path of the light L1 emitted from the light emitting portion 211 and a position avoiding the optical path. The operation of the mechanism is controlled, for example, by the control device 40. Fig.11 Part (a) shows a case where the reference reflection surface 28a is located on the optical path of the light L1 emitted from the light emitting section 211. In this case, the light L1 emitted from the light emitting section 211 is reflected by the reference reflection surface 28a. The reflected light from the reference reflection surface 28a is incident on the light incident section 212. Then, the light intensity of each wavelength of the reflected light is detected by the spectroscopic detection section 23. Thus, the calculation section 30 can obtain the reference light intensity used when calculating the reflectivity R of the polymer film B for each wavelength. When the reflectivity of the reference reflection surface 28a is 100%, the reference light intensity of each wavelength is equal to the light intensity of the wavelength component of the light L1. Fig.11 Part (b) of FIG. 2 shows a case where the reference reflection surface 28a is positioned so as to avoid the optical path of the light L1 emitted from the light emitting portion 211. In this case, the light L1 emitted from the light emitting portion 211 is reflected by the polymer film B. The reflected light L2 from the polymer film B is incident on the light incident portion 212. The light intensity of each wavelength of the reflected light L2 is detected by the spectroscopic detection portion 23. The calculation portion 30 calculates the refractive index n of the polymer film B based on these light intensities. The reference reflection surface 28a is maintained in a state of avoiding the optical path of the light L1, and as shown in FIG. Fig.11 As shown in part (c) of FIG. 2 , the linear guide 26 scans the optical unit 21A in the direction D2 intersecting the conveying direction D1. At this time, the calculation unit 30 can obtain the refractive index distribution by repeatedly calculating the refractive index n. The reference light intensity of the reference reflection surface 28a is obtained ( Fig.11 (a) of the method) is repeated at a predetermined timing. The predetermined timing is, for example, when the operation of the measuring device starts or after a predetermined time has passed since the last acquisition.

[0068] As in this modification, the reference light intensity can also be obtained by irradiating the reference reflection surface 28a with known reflectivity with light L1 and obtaining the light intensity of the reflected light from the reference reflection surface 28a. Thus, the incident light intensity can be known with good accuracy. Therefore, in this case, for example, even if the light intensity of the light L1 emitted from the light emitting portion 211, that is, the incident light intensity, changes over time, the refractive index distribution can be measured with good accuracy.

[0069] As in this modification, the optical unit 21A of the light intensity acquisition unit 20 may include a reference reflection surface 28a and a mechanism for changing the position of the reference reflection surface 28a between a position on the optical path of the light L1 and a position away from the optical path. In this case, the reference light intensity can be easily acquired.

[0070] [Second Modification]

[0071] Fig.12 Parts (a), (b), and (c) are front views showing a part of the structure of the light intensity acquisition section as a second variant. In these figures, the polymer film B is shown by a cross section cut along a plane perpendicular to the conveying direction D1. The light intensity acquisition section has a reflection plate 28 in addition to the structure of the light intensity acquisition section 20 of the above-mentioned embodiment. The structure of the reflection plate 28 is the same as that of the first variant except for the following points. The reflection plate 28 of this variant is provided independently of the optical unit 21, and is arranged in the direction D2 relative to the polymer film B. Furthermore, the linear guide 26 is configured to scan the optical unit 21 in the range from the polymer film B to the reflection plate 28. Fig.12 Part (a) shows a case where the optical unit 21 is located on the reference reflection surface 28a. In this case, the light L1 emitted from the light emitting portion 211 is reflected by the reference reflection surface 28a. The reflected light from the reference reflection surface 28a is incident on the light incident portion 212. Then, the light intensity of each wavelength of the reflected light is detected by the spectroscopic detection portion 23, and the calculation portion 30 can obtain the reference light intensity used when calculating the reflectivity R of the polymer film B for each wavelength. Fig.12 Part (b) of FIG. 2 shows a case where the optical unit 21 is located on the polymer film B. In this case, the light L1 emitted from the light emitting portion 211 is reflected by the polymer film B. The reflected light L2 from the polymer film B is incident on the light incident portion 212. Then, the light intensity of each wavelength of the reflected light L2 is detected by the spectroscopic detection portion 23. The calculation portion 30 calculates the refractive index n of the polymer film B based on these light intensities. Then, as Fig.12 As shown in part (c) of FIG. 1 , the linear guide 26 scans the optical unit 21 along the direction D2 of the polymer film B. At this time, the calculation unit 30 can obtain the refractive index distribution by repeatedly calculating the refractive index n. In this modification, the reference light intensity of the reference reflection surface 28a is obtained ( Fig.12Part (a) of the present invention is also repeated in the above-specified timing.

[0072] [Third Modification]

[0073] Fig.13 1 is a diagram schematically showing the structure of a measuring device 1B according to a third modified example. The measuring device 1B is different from the measuring device 1A according to the above embodiment in that it includes a light intensity acquisition unit 20C instead of the light intensity acquisition unit 20 according to the above embodiment. The light intensity acquisition unit 20C is different from the light intensity acquisition unit 20 according to the above embodiment in that it does not include a linear guide 26 and a control unit 27, but is provided with a plurality of optical units 21. The other points are the same as the light intensity acquisition unit 20 according to the above embodiment. Fig.14 2 is a top view showing a plurality of optical units 21. A plurality of (four in the example shown) optical units 21 and a plurality of light spots SP (see FIG. 2 ) irradiated with the light L1 Figure 2 ) respectively. The plurality of optical units 21 are arranged along a direction D2 intersecting the conveying direction D1. The intervals between the plurality of optical units 21 may also be uniform. In this embodiment, the light source unit 22, the spectroscopic detection unit 23, the light guide members 24 and 25, and the computing unit 30 are arranged corresponding to each optical unit 21.

[0074] As in this modification, the light intensity acquisition unit 20C may include a plurality of optical units 21 corresponding to the plurality of light spots SP, respectively. For example, even with such a configuration, the light L1 may be irradiated to the plurality of light spots SP, and the light intensity of the reflected light L2 from the plurality of light spots SP irradiated with the light L1 may be acquired. Then, the refractive index distribution and the film thickness distribution in the direction D2 intersecting the conveying direction D1 may be measured.

[0075] The light intensity acquisition unit 20C may include a plurality of optical units 21A according to the first modification instead of the plurality of optical units 21 . Fig.15 Parts (a) and (b) of FIG. 1 are front views showing a state where a plurality of (four in the example shown) optical units 21A are arranged in a row along the direction D2. Fig.15 Part (a) shows a case where the reference reflection surface 28 a is located on the optical path of the light L1 emitted from the light emitting portion 211 . Fig.15 Part (b) shows a case where the reference reflection surface 28a is positioned so as to avoid the optical path of the light L1 emitted from the light emitting portion 211. The operation of the light intensity acquisition portion 20C in these cases is the same as that of the light intensity acquisition portion of the first modification.

[0076] The refractive index distribution measuring device, film thickness distribution measuring device, refractive index distribution measuring method, and film thickness distribution measuring method of the present invention are not limited to the above-mentioned embodiments and variations, and other various variations are possible. For example, the above-mentioned variation 1 to variation 3 may be combined with each other according to the desired purpose and effect.

[0077] Those skilled in the art will recognize that the principles of the present invention are illustrated in the preferred embodiments, but the present invention may be changed in configuration and details without departing from such principles. The present invention is not limited to the specific structure disclosed in this embodiment. Therefore, all modifications and changes from the claims and their spirit and scope are claimed.

[0078] Explanation of symbols

[0079] 1A, 1B…measuring device, 10…conveying section, 11…roller pair, 11a, 11b…rollers, 20, 20C…light intensity acquiring section, 21, 21A…optical unit, 22…light source section, 23…spectral detection section, 24, 25…light guide member, 26…linear guide, 27…control unit, 28…reflection plate, 28a…reference reflection surface, 30…calculating section, 31…processor, 32…ROM, 34…auxiliary storage device, 40…control device, 41…conveying control section, 42…scanning control section, 43…detection control section, 54…input device, 55…monitor, 60…measuring unit, 211…light emitting section, 212…light incident section, B…polymer film, Ba…main surface, Bb…surface, d…film thickness, D1…conveying direction, D2…direction, L1…light, L2…reflected light, SP…light spot

Claims

1. A refractive index distribution measuring device, in, have: a conveying unit that conveys the polymer film in the first direction; a light intensity acquisition unit for irradiating light onto a plurality of light spots arranged in a second direction intersecting the first direction in the polymer film being conveyed, and acquiring light intensities of reflected light from the plurality of light spots irradiated with the light; and A calculation unit calculates a reflectance at each of the plurality of light spots from the light intensity of the reflected light acquired by the light intensity acquisition unit, and obtains a refractive index distribution of the polymer film in the second direction based on the reflectance.

2. The refractive index distribution measuring device according to claim 1, in, The calculation unit calculates the reflectivity of each of the multiple light points based on the ratio of the light intensity of the reflected light from each of the multiple light points to a reference light intensity, wherein the reference light intensity is obtained by irradiating the light from the light intensity acquisition unit to a reference reflection surface with known reflectivity and acquiring the light intensity of the reflected light from the reference reflection surface in the light intensity acquisition unit.

3. The refractive index distribution measuring device according to claim 2, in, The light intensity acquisition unit includes: The reference reflection surface; and A mechanism for changing the position of the reference reflection surface between a position on an optical path of the light emitted from the light intensity acquisition unit and a position away from the optical path.

4. The refractive index distribution measuring device according to any one of claims 1 to 3, in, The light intensity acquisition unit includes a plurality of optical units corresponding to the plurality of light spots, respectively. The plurality of optical units respectively include a light emitting portion for emitting the light and a light incident portion for receiving the reflected light.

5. The refractive index distribution measuring device according to any one of claims 1 to 3, in, The light intensity acquisition unit includes: an optical unit comprising a light emitting portion for emitting the light and a light incident portion for receiving the reflected light; and A scanning unit scans the optical unit in a direction intersecting the first direction.

6. The refractive index distribution measuring device according to any one of claims 1 to 5, in, The calculation unit further obtains the refractive index distribution based on the extinction coefficient of the polymer film.

7. The refractive index distribution measuring device according to any one of claims 1 to 6, in, The wavelength band of the light is a visible wavelength region, or a wavelength band ranging from the visible wavelength region to the near-infrared wavelength region.

8. The refractive index distribution measuring device according to any one of claims 1 to 6, in, The wavelength band of the light includes a near-infrared wavelength region.

9. A film thickness distribution measuring device, in, A refractive index distribution measuring device according to any one of claims 1 to 8, The calculation unit further obtains a film thickness distribution of the polymer thin film in the second direction based on the light intensity of the reflected light at each of the plurality of light spots acquired by the light intensity acquisition unit and the refractive index distribution.

10. A method for measuring refractive index distribution, in, Include: A step of starting to transport the polymer film in a first direction; A step of irradiating light onto a plurality of light spots arranged in a second direction intersecting the first direction in the polymer film being conveyed, and obtaining light intensities of reflected light from the plurality of light spots irradiated with the light; and A step of calculating a reflectance at each of the plurality of light spots from the light intensity of the reflected light acquired in the acquiring step, and obtaining a refractive index distribution of the polymer film in the second direction based on the reflectance.

11. The refractive index distribution measuring method according to claim 10, in, In the step of obtaining the refractive index distribution, the reflectivity at each of the multiple light points is calculated based on the ratio of the light intensity of the reflected light from each of the multiple light points to a reference light intensity, wherein the reference light intensity is obtained by irradiating the light to a reference reflection surface having a known reflectivity and obtaining the light intensity of the reflected light from the reference reflection surface.

12. The refractive index distribution measuring method according to claim 10 or 11, in, In the step of obtaining the refractive index distribution, the refractive index distribution is obtained based on an extinction coefficient of the polymer film.

13. The refractive index distribution measuring method according to any one of claims 10 to 12, in, The wavelength band of the light is a visible wavelength region, or a wavelength band ranging from the visible wavelength region to the near-infrared wavelength region.

14. The refractive index distribution measuring method according to any one of claims 10 to 12, in, The wavelength band of the light includes a near-infrared wavelength region.

15. A method for measuring film thickness distribution, in, A refractive index distribution measuring method comprising any one of claims 10 to 14, The method further includes: a step of obtaining a film thickness distribution of the polymer film in the second direction based on the light intensity of the reflected light at each of the plurality of light points obtained in the step of obtaining the light intensity and the refractive index distribution obtained in the step of obtaining the refractive index distribution.

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