JP2011117792A - Device for measuring lamination angle of elliptically polarized light plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a lamination angle between the transmission axis of a polarized light plate, in a short time, and a phase delaying axis or a phase advancing axis of a retardation plate, in an elliptically polarized light plate. <P>SOLUTION: A polarizer 3 and an analyzer 6 are disposed on a measuring optical path, along which measuring light obtained by making light from a light source 1 be of a single wavelength via a band-pass filter 2 reaches a photodetector 8. The elliptically polarized light plate 5 is disposed as a measuring object sample, on the measuring optical path between the polarizer 3 and the analyzer 6, and the changes in the transmitted light intensity in a circular portion inside the polarizer and the analyzer and an annular portion outside them, when the polarizer 3 and the analyzer 6 rotated by a single rotation, respectively, are separated by a light guide 7 and are led to the photodetector 8 separately, so that the lamination angle of the polarized light plate and the retardation plate of the elliptically polarized light plate is measured, from the difference in the direction of maximum transmitted light intensity of two figures of the changes of the transmitted light intensity in the portions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for measuring a bonding angle of an elliptically polarizing plate in which a polarizing plate and a retardation plate used in a liquid crystal display device are bonded.

  In general, in the laminate 5 in which the polarizing plate 5a and the retardation plate 5b are bonded as shown in FIG. 7A, light transmitted from the polarizing plate 5a through the retardation plate 5b becomes elliptically polarized light. , Called an elliptically polarizing plate. One of the polarization analysis methods of such transmitted light is the ellipticity from the intensity change of the entire transmitted light when the polarizing plate (analyzer or polarizer) disposed on the phase difference plate side of the elliptical polarizing plate is rotated. There is a rotating analyzer method or a rotating polarizer method for measuring an elliptical azimuth angle. The method is such that the retardation of the retardation plate is 100 nm or more, as represented by an elliptical polarizing plate for compensation of STN (Super Twisted Nematic) type liquid crystal cells, and the bonding angle between the polarizing plate and the retardation plate ( If the elliptically polarizing plate has an angle between the transmission axis of the polarizing plate and the slow axis or fast axis of the retardation plate in the range of about 20 ° to about 70 °, the retardation of the retardation plate Both the bonding angles of the elliptically polarizing plates can be measured with high accuracy (see Patent Document 1).

  However, VA (Vertical Alignment) type liquid crystal cells and IPS (In-Plane Switching) type liquid crystal cells are widely used in recent liquid crystal display devices, and elliptical polarizing plates used for them are polarizing plates and retardation plates. May be processed so that the bonding angle is approximately 0 ° or approximately 90 °. The term “substantially” is used here because it is not only set to exactly 0 ° or 90 °, but also may have been designed with an angle of several degrees from 0 ° or 90 ° in the specification. is there. In any case, in order to measure the degree of deviation angle with respect to the target bonding angle, a method of measuring with a measuring device having a configuration including a rotating analyzer, a rotating polarizer, and a wave plate. (See Patent Document 2).

  As a measurement system for measuring the bonding angle, a measurement system as shown in FIG. 9 is used. In the measurement system, light from the light source device 1 is converted into single-wavelength measurement light through the band-pass filter 2, and the polarizer 3 and the analyzer 6 are arranged on the measurement optical path where the measurement light reaches the photodetector 8. The On the measurement optical path between the polarizer 3 and the analyzer 6, the elliptically polarizing plate 5 in which the polarizing plate 5a and the retardation plate 5b are bonded is arranged as a measurement object so that the retardation plate 5b is on the light source side. . A wave plate 4 is disposed on the measurement optical path between the polarizer 3 and the object to be measured. The polarizer 3, the wave plate 4 and the analyzer 6 can rotate around the optical axis of the measurement optical path. Further, the polarizer 3 and the wave plate 4 are arranged so as to be movable between a position on the measurement optical path and a position off the measurement optical path.

ここで、Ｉ₀₁は被測定物がないときの透過光強度、θaは検光子６の回転角、Ｔpy，Ｔpxは検光子６の透過軸方向と吸収軸方向のそれぞれの透過率、Ｔsy，Ｔsxは被測定物の楕円偏光板５の偏光板の透過軸方向と吸収軸方向のそれぞれの透過率、φpは被測定物の楕円偏光板５の偏光板の透過軸方位である。 First, a case where an elliptically polarizing plate for STN type liquid crystal cell compensation is measured will be described. In this case, it is not necessary to provide the wave plate 4 in the measurement system shown in FIG. First, when only the analyzer 6 is rotated once in a state where the polarizer 3 and the wave plate 4 are not in the measurement system as shown in FIG. 10A, a change in transmitted light intensity as shown in FIG. 8A is obtained. Since the change in the light intensity is expressed by equation (1), the transmission axis azimuth φp of the polarizing plate 5a of the object to be measured 5 is obtained by curve fitting calculation processing.

Here, I ₀₁ is the transmitted light intensity when there is no object to be measured, θa is the rotation angle of the analyzer 6, Tpy, Tpx are the respective transmittances in the transmission axis direction and the absorption axis direction of the analyzer 6, Tsy, Tsx Is the transmittance in the transmission axis direction and the absorption axis direction of the polarizing plate of the elliptically polarizing plate 5 of the object to be measured, and φp is the transmission axis direction of the polarizing plate of the elliptically polarizing plate 5 of the object to be measured.

ここで、Ｉ₀₂は被測定物がないときの透過光強度、θpは偏光子３の回転角、ψは楕円偏光板５の偏光板と位相差板の貼合角、λは測定波長、Ｒeは位相差板の位相差である。 After obtaining φp, the analyzer 6 is rotated and fixed so that the transmission axis direction of the analyzer 6 becomes the transmission axis direction φp of the polarizing plate of the object to be measured as shown in FIG. Next, when the polarizer 3 is put into the measurement system and the polarizer 3 is rotated once, a change in transmitted light intensity as shown in FIG. 8B is obtained. Since the change in the light intensity is expressed by equation (2), the bonding angle ψ between the polarizing plate of the object to be measured 5 and the retardation film is obtained by curve fitting calculation processing.

Here, I ₀₂ is the transmitted light intensity when there is no object to be measured, θp is the rotation angle of the polarizer 3, ψ is the bonding angle between the polarizing plate of the elliptically polarizing plate 5 and the retardation plate, λ is the measurement wavelength, Re Is the phase difference of the phase difference plate.

On the other hand, in the elliptically polarizing plate bonded with the transmission axis of the polarizing plate and the slow axis or the fast axis of the retardation plate at approximately 0 ° or approximately 90 °, the transmitted light is almost linearly polarized. The elliptically polarizing plate may be referred to as a composite polarizing plate or a laminated polarizing plate. When measuring a composite polarizing plate, the transmitted light intensity diagram when the polarizer 3 is rotated once in the state of FIG. 10B does not become as shown in FIG. It becomes almost the same figure. In such a case, an accurate bonding angle ψ cannot be obtained by the curve fitting of equation (2). Therefore, in the method described in Patent Document 2, an elliptical polarizing plate bonded at an angle slightly shifted from 0 ° or 90 °, or an elliptical polarizing plate bonded at 0 ° or 90 °. In order to measure the laminating angle, the ellipticity and elliptical azimuth of the transmitted light are obtained by the measurement of FIG. 10B after the measurement of FIG. 10A, and then as shown in FIG. After placing the wave plate 4 in the measurement system and rotating and fixing it so that the slow axis or the fast axis of the wave plate 4 is φp + 45 °, the polarizer 3 is further rotated once to obtain the ellipticity of the transmitted light. Obtain the ellipse azimuth. In general, the ellipticity and elliptical azimuth angle of transmitted light can be obtained relatively easily from the transmitted light intensity diagram I (θ). When the azimuth Ψ of the polarizer 3 giving the minimum value Imin, the maximum value Imax and the maximum value of I (θ) of I (θ) is obtained, the ellipticity is (Imin / Imax) ^1/2 and the elliptical azimuth is Ψ. It is expressed. Therefore, assuming that the elliptical azimuth angle expressed on the basis of φp is ψ ′, ψ ′ = ψ−φp. The method described in Patent Document 2 uses a phenomenon in which the ellipticity of transmitted light and the elliptical azimuth change when only an elliptically polarizing plate is used, and the ellipticity after overlapping the wavelength plates. By comparing the measured values of the elliptical azimuth angle with the simulation result, it is possible to measure the bonding deviation angle or the bonding angle of the composite polarizing plate.

Japanese Patent No. 3539006 JP 2009-122152 A

  When the target bonding angle between the polarizing plate and the retardation plate is approximately 0 ° or approximately 90 °, even if there is a deviation of several degrees in the bonding angle, the elliptical polarizing plate as shown in FIG. The transmitted light is almost the same as the linearly polarized light after passing through the polarizing plate constituting the elliptically polarizing plate. The above-described conventional method (the method described in Patent Document 2) uses a measuring device as shown in FIG. 9 and first measures the analyzer 6 with the wave plate 4 and the polarizer 3 not in the measuring system in one point measurement. Rotate to measure the transmission axis azimuth φp of the polarizing plate of the composite polarizing plate 5, and then put the polarizer 3 into the measuring system and rotate it once, and further put the wave plate 4 into the measuring system to delay the wave plate 4. After rotating and fixing so that the axis or the fast axis is φp + 45 °, a procedure of further rotating the polarizer 3 is required. The method is fixed as a reliable method for measuring the bonding misalignment angle of the composite polarizing plate, but the measurement time per point becomes long.

  Even in the case of an elliptically polarizing plate whose bonding angle is in the range of about 20 ° to about 70 °, the conventional method using the measuring device as shown in FIG. 9 (the method described in Patent Document 1) is first polarized. With the probe 3 and the wave plate 4 not in the measurement system, only the analyzer 6 is rotated once to determine the transmission axis azimuth φp of the polarizing plate 5a of the object to be measured. In a state where the polarizer 3 is fixed in accordance with the transmission axis azimuth φp of the polarizing plate, the polarizer 3 is put into the measuring system and the polarizer 3 is rotated once to thereby obtain the bonding angle ψ between the polarizing plate of the object to be measured 5 and the retardation plate. Therefore, although this method is also established as a method that can accurately measure the bonding angle of the elliptically polarizing plate, the measurement time per point is also long.

  An object of the present invention is to make it possible to measure a bonding angle between a transmission axis of a polarizing plate and a slow axis or a fast axis of a retardation plate in an elliptical polarizing plate in a short time.

  The laminating angle measuring apparatus of the present invention will be described with reference to FIG. 1 showing an embodiment. The apparatus includes a polarizing plate 5a and a retardation plate 5b, and a transmission axis of the polarizing plate 5a and a slow axis of the retardation plate 5b. Or the light source optical systems 1 and 2 that irradiate the measurement light of the single wavelength from the retardation plate side 5b to the object to be measured 5 composed of the elliptically polarizing plate with the fast axis bonded with the bonding angle ψ, A polarizer 3 disposed between the light source optical systems 1 and 2 and the object to be measured 5, an analyzer 6 disposed on the opposite side of the polarizer 3 with respect to the object to be measured 5, and measurement light are detected. Photodetectors 8-1 and 8-2 and an arithmetic processing unit 9 that takes in the detection signals of the photo detectors 8-1 and 8-2 and calculates a bonding angle ψ of the DUT 5.

  And the polarizer 3 consists of a 1st rotation disc, and it is a polarizing plate only to a part of surface of a 1st rotation disc, and the inner circular part (or outer annular part) inside a 1st rotation disc. Are arranged, and a region other than the polarizing plate arrangement region is a light transmission region.

  The analyzer 6 is composed of a second rotating disk having a rotation center coaxially with the rotation axis of the first rotating disk, and the polarization of the first rotating disk in a region along the circumference of the surface of the second rotating disk. A polarizing plate is disposed only in a region that does not overlap the plate placement region, and a region other than the polarizing plate placement region is a light transmission region.

  The photodetectors 8-1 and 8-2 include only the first photodetector 8-1 that detects the measurement light transmitted through only the polarizing plate arrangement region of the analyzer 6 and the polarizing plate arrangement region of the polarizer 3. It comprises a second photodetector 8-2 that detects the transmitted measurement light.

  The arithmetic processing unit 9 takes in the detection signals of the first photodetector 8-1 and the second photodetector 8-2, and the transmission axis of the polarizing plate of the object to be measured from the detection signal of the first photodetector 8-1. The azimuth φp is obtained, the obtained transmission axis azimuth φp and the known phase difference Re of the retardation plate of the object to be measured are used, and the bonding angle ψ of the object to be measured using the detection signal of the second photodetector 8-2. Is calculated.

  The elliptically polarizing plate to be measured is not limited to an elliptically polarizing plate called a composite polarizing plate bonded at approximately 0 ° or approximately 90 °, but is bonded like an elliptically polarizing plate for STN type liquid crystal cell compensation. Also included is an elliptically polarizing plate with an alignment angle in the range of about 20 ° to about 70 °.

  The 1st form of this invention is a bonding angle measuring apparatus which makes the to-be-measured object the elliptically polarizing plate bonded with the bonding angle of about 0 degree or about 90 degrees as a target. As shown in FIG. 2, the arithmetic processing unit 9 in this case has a transmission axis azimuth φp calculation means 22, an elliptical azimuth angle Ψ calculation means 24, an elliptical azimuth angle Ψ ′ calculation means 26, and ψ vs Ψ ′, Re relationship retention. A unit 28 and a bonding angle ψ calculating means 32 are provided.

  The transmission axis azimuth φp calculation means 22 transmits the transmission axis azimuth of the polarizing plate of the object to be measured from the maximum transmission light intensity azimuth of the transmitted light intensity figure by the detection signal of the first photodetector 8-1 when the analyzer is rotated once. Find φp.

  The ellipse azimuth angle Ψ calculating means 24 obtains the ellipse azimuth angle Ψ of the object to be measured from the maximum transmitted light intensity azimuth of the transmitted light intensity diagram based on the detection signal of the second photodetector 8-2 when the polarizer is rotated once. .

  The ellipse azimuth angle ψ ′ calculating means 26 is a φp-based ellipse azimuth angle as a difference between the ellipse azimuth angle Ψ obtained by the ellipse azimuth angle Ψ calculating means 24 and the transmission axis azimuth φp obtained by the transmission axis azimuth φp calculating means. Ψ ′ (= Ψ−φp) is calculated.

  The ψ pair ψ ′, Re relationship holding unit 28 holds the relationship between the bonding angle ψ of the elliptically polarizing plate, the elliptic azimuth angle ψ ′, and the phase difference Re of the retardation plate.

  Then, the bonding angle ψ calculating means 32 has an elliptical azimuth angle ψ ′ determined by the elliptical azimuth angle ψ ′ calculating means 26 in the ψ pair ψ ′, Re relationship held in the ψ pair ψ ′, Re relationship holding unit 28. And the known phase difference Re of the retardation plate of the object to be measured is applied to calculate the bonding angle ψ of the object to be measured.

  In this embodiment, the transmitted light intensity figures obtained by the two photodetectors 8-1 and 8-2 in FIG. 1 are almost as shown in FIG. The azimuth of the maximum intensity obtained from the transmitted light intensity diagram of the polarizing plate arrangement region of the analyzer 6 is φp, and the azimuth of the maximum intensity obtained from the transmitted light intensity diagram of the polarizing plate arrangement region of the polarizer 3 is Ψ. The difference between φp and Ψ, that is, Ψ ′ is slight and at most 1 ° or less.

ここで、Ｉmax、Ｉminは透過光強度の最大値、最小値、θは偏光子又は検光子の回転角、φは最大透過光強度の方位であってφp又はΨに相当する。（４）式は未知数３つで簡潔なため、（１）式で表すよりもカーブフィッティングの精度が良くなり、求めるφpとΨの値も安定する。φpとΨが求まればそれらの差Ψ'も求まる。 Further, the figure as shown in FIG. 8A is expressed by the equation (1), but the equation (1) includes four unknowns I ₀₁ , Tsy, Tsx, and φp. In the present invention, since it is not necessary to determine the transmittances Tsy and Tsx of the polarizing plate of the object to be measured, here, the transmitted light intensity diagrams obtained by the two photodetectors 8-1 and 8-2 in FIG. Instead of equation (1), the following equation is used.

Here, Imax and Imin are the maximum and minimum values of transmitted light intensity, θ is the rotation angle of the polarizer or analyzer, φ is the direction of the maximum transmitted light intensity, and corresponds to φp or Ψ. Since the equation (4) is simple with three unknowns, the accuracy of curve fitting is better than that represented by the equation (1), and the obtained values of φp and Ψ are also stable. If φp and Ψ are obtained, the difference Ψ ′ between them is also obtained.

In equations (2) and (3), if the wavelength λ and the transmission axis φp of the polarizing plate are kept constant, and the calculation is performed by changing the bonding angle ψ and the phase difference Re, the transmitted light intensity diagram I (θ) can be freely set. The azimuth ψ ′ of the maximum transmitted light intensity based on φp at that time can be easily obtained. For example, ψ ′ when λ is 590 nm and ψ is changed from 0 ° to 0.5 ° and Re is changed from 50 nm to 160 nm is calculated. From FIG. 4, it can be seen that ψ and ψ ′ are in a linear relationship, and the inclination changes depending on Re. Therefore, when the relationship between the slope of each straight line and Re in FIG. 4 is graphed, it is as shown in FIG. Therefore, if the phase difference Re of the object to be measured is known, the bonding angle ψ can be calculated by the following equation by measuring ψ ′.

  The coefficient of equation (5) varies depending on the measurement wavelength, but can be treated as a device constant as long as measurement is performed at a fixed wavelength.

  In the arithmetic processing unit 9 shown in FIG. 2, the equation (5) is held in the ψ pair ψ ′, Re relationship holding unit 28. The phase difference Re of the object to be measured may be inputted and held as a known value from the input unit to the arithmetic processing unit 9.

  FIG. 6 is a graph showing the relationship between ψ ′ and the bonding angle ψ for each phase difference Re based on the approximate expression obtained in FIG. The calculation process in the bonding angle ψ calculating unit 32 corresponds to obtaining the bonding angle ψ from the phase difference Re and ψ ′ in FIG. 6.

  In the present invention, the phase difference Re is treated as known, but the fluctuation of the phase difference Re of the phase difference plate used in the liquid crystal display device is very small, and even if estimated, it is 2 nm or less with respect to the target value. If Re = 50 nm and 100 nm in Equation (5) and ψ = 0.2 ° and 0.5 °, Re of the actual object to be measured was (target value + 2 nm), respectively. Table 1 shows how much the ψ obtained from the equation (5) changes.

  From Table 1, the bonding angle ψ measured when measuring an object whose Re deviates by 2 nm from the target value while using the target Re value is affected by about 0.04 °. I understand. This error can be said to be sufficiently usable in view of the required measurement accuracy of ψ ± 0.1 °.

  The 2nd form of this invention is a bonding angle measuring apparatus which uses the elliptically polarizing plate in the range whose bonding angle is about 20 degrees-about 70 degrees as a to-be-measured object. As shown in FIG. 3, the arithmetic processing unit 9 in this case includes a transmission axis azimuth φp calculation unit 22 and a bonding angle ψ calculation unit 32a.

  The transmission axis azimuth φp calculation means 22 is the same as that of the first embodiment, and the maximum transmission light intensity azimuth of the transmission light intensity figure by the detection signal of the first photodetector 8-1 when the analyzer is rotated once. The transmission axis direction φp of the polarizing plate of the object to be measured is obtained.

  The bonding angle ψ calculating means 32a uses the transmission axis azimuth φp obtained by the transmission axis azimuth φp calculating means 22 and the known phase difference Re of the retardation plate of the object to be measured, and the second light when the polarizer is rotated once. The bonding angle ψ of the object to be measured is calculated by curve fitting in which the expressions (2) and (3) are applied to the transmitted light intensity diagram based on the detection signal of the detector 8-2.

  The second mode is used when measuring a bonding angle of an elliptical polarizing plate for STN type liquid crystal cell compensation, and the same calculation procedure as in Patent Document 1 without using the formula (5) ( 2) The bonding angle is obtained from the formula (3).

  According to the bonding angle measuring device of the present invention, the bonding angle when the bonding angle between the polarizing plate constituting the elliptically polarizing plate and the retardation plate is approximately 0 ° or approximately 90 °. Or not only the deviation angle from the target bonding angle but also the measurement of the bonding angle of elliptical polarizing plates with a bonding angle in the range of about 20 ° to about 70 °, the polarizer and the analyzer are rotated once each. Therefore, the measurement time can be shortened.

It is a schematic block diagram of one Example of the measurement system for measuring the elliptically polarizing plate of this invention. It is a block diagram which shows the arithmetic processing part in a 1st form. It is a block diagram which shows the arithmetic processing part in a 2nd form. It is a graph showing the relationship between the phase difference Re of the composite polarizing plate obtained by calculation, the bonding angle ψ, and the difference ψ ′ of the polarization azimuth angles of two transmitted lights observed. It is a graph which shows the relationship between the phase difference Re of the graph of FIG. 4, and the inclination of each straight line. It is the graph which showed the relationship between (PSI) 'and the bonding angle (PSI) for every phase difference Re based on the approximate expression obtained in FIG. (A) is an elliptically polarizing plate, (b) is a schematic perspective view explaining the polarization state of the transmitted light of an elliptically polarizing plate called a composite polarizing plate. (A) is a transmitted light intensity diagram when the transmission axis of the polarizing plate is measured by the measurement system of FIG. 10 (a), and (b) is a transmitted light when the elliptical polarizing plate is measured by the measurement system of FIG. 10 (b). It is an intensity figure. It is a schematic block diagram which shows an example of the measurement system for measuring the composite polarizing plate of a conventional method. It is the schematic block diagram which showed the motion of the optical system when measuring the composite polarizing plate of the conventional method in order.

  Drawing 1 is a schematic structure figure showing one example of a pasting angle measuring device for measuring a pasting angle in an elliptically polarizing plate.

  Light from the light source 1 is applied to the elliptically polarizing plate 5 which is an object to be measured as measurement light of single wavelength light. As the light source 1, it can consist of a halogen lamp and the light guide which guides the light from a halogen lamp, for example. In that case, the band pass filter 2 is arranged on the optical path in order to change the light from the halogen lamp to single wavelength light. A laser light source can also be used as the light source 1. In the case of a laser light source, the bandpass filter 2 can be omitted by oscillating single wavelength light. In the following description, a halogen lamp is used as the light source 1 and the band-pass filter 2 is disposed.

  Furthermore, it is preferable that an optical system for making the measurement light parallel light is disposed between the light source 1 and the band pass filter 2.

  On the optical path of the measurement light between the position on the sample stage where the bandpass filter 2 and the elliptically polarizing plate 5 are arranged, two concentric circles with different diameters are formed in the inner circle. A polarizer 3 is arranged. In order to detect the measurement light transmitted through the elliptically polarizing plate 5, two photodetectors 8-1 and 8-1 are arranged. On the measurement optical path between the elliptically polarizing plate 5 and the photodetectors 8-1 and 8-2, two concentric circles having different diameters as in the polarizer 3, and the outer annular portion becomes a polarizing plate. An analyzer 6 is arranged. The polarizer 3 and the analyzer 6 are rotatably supported so that the direction of the polarization axis can be changed, and are configured to rotate synchronously with one motor, and the rotation angle can be detected by an encoder. ing.

  A light guide 7 is disposed between the analyzer 6 and the photodetectors 8-1 and 8-2. The light guide 7 is formed by bundling a large number of optical fibers so that one end surface is a circular incident surface. The annular portion of the incident end face of the light guide 7 receives the measurement light passing through the transparent glass region of the polarizer 3 and passing through the polarizing plate arrangement region of the analyzer 6 and guides it to the first photodetector 8-1. . A circular portion at the center of the incident end face of the light guide 7 receives the measurement light that has passed through the polarizing plate arrangement region of the polarizer 3 and has passed through the transparent glass region of the analyzer 6, and receives the second photodetector 8-2. Lead to.

  An arithmetic processing unit 9 for obtaining the direction of the maximum transmitted light intensity of each of the two transmitted light intensity diagrams based on the detection signals of the photodetectors 8-1 and 8-2 and calculating the bonding angle from these values. Is provided. The arithmetic processing unit 9 fulfills the functions shown in FIG. 2 or FIG. 3, and is realized by a dedicated computer or a computer that controls the operation of this measuring apparatus.

  The polarizer 3 and the analyzer 6 are not necessarily driven by a single motor, and may be independently rotated as long as the rotation angle can be detected.

DESCRIPTION OF SYMBOLS 1 Light source 2 Band pass filter 3 Polarizer 4 Wave plate 5 Composite polarizing plate 6 Analyzer 7 Ride guide 8 Photo detector 9 Arithmetic processing part 22 Transmission axis direction φp calculation means 24 Ellipse azimuth angle Ψ calculation means 26 Ellipse azimuth angle Ψ ′ Calculation means 28 ψ pair ψ ′, Re relationship holding section 32, 32a Bonding angle ψ calculation means

Claims (5)

For an object to be measured comprising an elliptically polarizing plate comprising a polarizing plate and a retardation plate, and a transmission axis of the polarizing plate and a slow axis or a fast axis of the retardation plate are bonded with a bonding angle ψ. A light source optical system that emits measurement light of a single wavelength from the phase difference plate side;
A first rotating disk disposed between the light source optical system and the object to be measured, which is a part of the surface of the first rotating disk and is an inner circular part inside the first rotating disk Or a polarizer in which a polarizing plate is arranged only in the outer annular portion, and a region other than the polarizing plate arrangement region is a light transmission region,
A second rotating disk is disposed on the opposite side of the measured object from the polarizer and has a rotation center coaxially with the rotation axis of the first rotating disk, the surface of the second rotating disk being An analyzer in which a polarizing plate is arranged only in a region that does not overlap with a polarizing plate arrangement region of the first rotating disk in a region along the circumference, and a region other than the polarizing plate arrangement region is a light transmission region;
A first photodetector for detecting measurement light transmitted through only the polarizing plate arrangement region of the analyzer;
A second photodetector for detecting measurement light transmitted only through the polarizing plate arrangement region of the polarizer;
The detection signals of the first photodetector and the second photodetector are taken in, the transmission axis direction φp of the polarizing plate of the object to be measured is obtained from the first photodetector signal, the obtained transmission axis direction φp and the measured object An arithmetic processing unit that calculates a bonding angle ψ of the object to be measured using a known phase difference Re of the object phase difference plate and a second photodetector signal;
A bonding angle measuring device comprising: The bonding angle measuring device is a bonding angle measuring device having an elliptically polarizing plate bonded with a bonding angle of approximately 0 ° or approximately 90 ° as a target,
The arithmetic processing unit
A transmission axis direction φp calculating means for obtaining a transmission axis direction φp of the polarizing plate of the object to be measured from the maximum transmitted light intensity direction of the transmitted light intensity diagram by the first photodetector signal when the analyzer is rotated once;
An elliptical azimuth angle Ψ calculating means for obtaining an elliptical azimuth angle Ψ of the object to be measured from the maximum transmitted light intensity azimuth of the transmitted light intensity pattern by the second photodetector signal when the polarizer is rotated once;
As a difference between the elliptical azimuth angle Ψ obtained by the elliptical azimuth angle Ψ calculating means and the transmission axis azimuth φp obtained by the transmission axis azimuth φp calculating means, the elliptical azimuth angle Ψ ′ (= Ψ−φp) based on φp Ellipse azimuth angle Ψ ′ calculating means for calculating;
Ψ pair Ψ ′, Re relationship holding unit holding the relationship between the bonding angle ψ of the elliptical polarizing plate and the elliptical azimuth angle ψ ′ and the phase difference Re of the phase difference plate;
The elliptical azimuth angle Ψ ′ obtained by the elliptical azimuth angle Ψ ′ calculating means in the ψ pair Ψ ′, Re relation held in the ψ pair Ψ ′, Re relationship holding unit and the known retardation plate of the object to be measured The bonding angle measuring device according to claim 1, further comprising: a bonding angle ψ calculating unit that calculates the bonding angle ψ of the object to be measured by applying the phase difference Re. The bonding angle measuring device is a bonding angle measuring device in which an elliptically polarizing plate having a bonding angle in the range of about 20 ° to about 70 ° is used as an object to be measured.
The arithmetic processing unit
A transmission axis direction φp calculating means for obtaining a transmission axis direction φp of the polarizing plate of the object to be measured from the maximum transmitted light intensity direction of the transmitted light intensity diagram by the first photodetector signal when the analyzer is rotated once;
Using the transmission axis direction φp obtained by the transmission axis direction φp calculating means and the known phase difference Re of the retardation plate of the object to be measured, transmission by the second photodetector signal when the polarizer is rotated once The bonding angle measuring device according to claim 1, further comprising a bonding angle ψ calculating unit that calculates a bonding angle ψ of the object to be measured by curve fitting of a light intensity graphic. The light source optical system includes a parallel optical system that irradiates the object to be measured with measurement light as a parallel light flux,
The polarizing plate arrangement region of the polarizer and the polarizing plate arrangement region of the analyzer are concentric, and one of the polarizer and the analyzer has the inner circular portion as the polarizing plate arrangement region and the outer annular portion is transparent. The paste according to any one of claims 1 to 3, wherein the other is a glass plate, and the other is a transparent glass plate in an inner circle portion and a polarizing plate arrangement region in an outer annular portion. Alignment measuring device.   The bonding angle measuring device according to any one of claims 1 to 4, wherein a rotation mechanism that rotates the polarizer and the analyzer rotates the polarizer and the analyzer simultaneously by a common motor.

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