KR20130124324A - Optical characteristic measuring device and method - Google Patents

Abstract

The optical properties of the optical film of the large area are measured quickly and with high accuracy. The optical film 12 to be measured is placed on the surface illuminating portion 14. Circularly polarized light is transmitted from the surface illuminating portion 14 toward the optical film 12. By moving the optical film 12 in the X direction, the measurement pixel E on the optical film 12 passes through the first to fourth imaging areas of the CCD camera in the imaging unit 15 in order. The CCD camera images the measurement pixel E a plurality of times when the measurement pixel E passes through each imaging area. The output value obtained by this multiple imaging is added as the measured value in the imaging area. The Stokes parameter of the measurement pixel E is calculated from the measured values of four imaging areas. Stokes parameters are acquired for all the measurement pixels E on the optical film 12.

Description

Optical property measuring apparatus and method {OPTICAL CHARACTERISTIC MEASURING DEVICE AND METHOD}

This invention relates to the optical characteristic measuring apparatus and method which measure the polarization characteristic of an optical film.

The functional plastic resin film (henceforth "optical film") which has various optical characteristics, such as a polarizing plate, a viewing angle correction film, and an antireflection film, is used for a liquid crystal display device. Since a liquid crystal display device obtains contrast using the birefringence characteristic which a liquid crystal has, it is necessary to also have predetermined birefringence characteristic also in the optical film to be used. When the birefringence characteristic of this optical film does not have uniformity over the whole surface, a nonuniformity will arise in the image display in a liquid crystal display device.

Therefore, before inserting an optical film into a liquid crystal display device, it is necessary to measure whether a film has a desired birefringence characteristic. The measurement of the birefringence characteristics includes a light source that irradiates the measurement light with respect to the optical film to be measured, a light receiver that receives the light emitted from the optical film, a phase difference plate and a polarizing plate for measuring polarization characteristics of the optical film, and the like. It is performed using various optical members.

For example, in patent document 1, various polarization states are produced by rotating the retardation plate placed between the light source and the CCD camera which is a light receiver around the optical axis. Then, images of different polarization states are picked up by a CCD camera, and birefringence characteristics are calculated for each pixel from the change in luminance value of each pixel of the image group obtained by imaging. Moreover, in patent document 2, the method of measuring online the birefringence characteristic of the optical film conveyed in a predetermined direction is disclosed. Moreover, in patent document 3, when performing a measurement while moving a film, the apparatus which measures birefringence distribution of the optical film of a large area is disclosed by repeating imaging in consideration of the visual field size of a CCD camera and the moving speed of an optical film. It is.

Japanese Unexamined Patent Publication No. 2009-229279 Japanese Patent Laid-Open No. 5-346397 Japanese Unexamined Patent Publication No. 2007-263593

In recent years, since the size of a liquid crystal display device is enlarged, the optical film with a large area also becomes the optical film inserted in it. In connection with this, the apparatus and the method which can measure the birefringence characteristic of the optical film which has a large area are calculated | required. For example, the liquid crystal display device of about 20 inches requires inspection of an optical film of size A3.

In this respect, in the prior art as shown in the above Patent Documents 1 to 3, there is a problem that the birefringence characteristics of the optical film of the optical area cannot be measured quickly and with high accuracy for the following reasons. In the case of Patent Literature 1, it is preferable to use a telecentric lens as the imaging lens. However, since one side of the lens is only about 5 cm, the A3 size cannot be inspected in one field of view.

Therefore, it is necessary to inspect the whole by dividing an optical film into several measurement areas according to the visual field of a CCD camera, and performing birefringence measurement for every said measurement area. At this time, in each measurement area, it is necessary to image while rotating the angle of a phase difference plate in the state which stopped a CCD camera in order to measure the polarization state of an optical film. Therefore, imaging (stop) in a predetermined measurement area → moves the CCD camera to another measurement area → imaging (stop) in another measurement area. Because of repeating the measurement, there was a problem that the measurement did not proceed very well and took time.

Moreover, in patent document 2, one point on an optical film is measured along a conveyance direction. Since there is no special rotation of the retardation plate, measurement can be performed without stopping the camera or the film. Therefore, in order to extend single point measurement to surface measurement, it is conceivable to arrange this measuring apparatus in the width direction of an optical film. However, when the measurement space resolution of the measuring device shown in Patent Literature 2 is, for example, 1 mm square, if the measuring device is arranged in the width direction of an optical film having an A3 size, 294 devices are required. Can not be said. The term "measurement space resolution" used here means the size of one measurement point on the measurement object, and when the distribution of the measurement result is finally imaged, it becomes the pixel size of the image.

Moreover, in the CCD camera used by patent document 3, since the polarizer required for the measurement of the polarization state of an optical film is formed in each light receiving element, it is not necessary to rotate a phase difference plate for every imaging like patent document 1. However, in this patent document 3, since the problem of the noise which a CCD camera has is not solved, high precision measurement cannot be performed.

In patent document 3, the measurement of one visual field size is performed based on one image obtained by one imaging of a CCD camera. In the CCD camera, even when continuous imaging is performed under the same conditions, a variation in value occurs in the output value obtained each time due to the variation in luminance due to the noise of the CCD. That is, in patent document 3, it cannot be said that reproduction of a measurement is inadequate.

The present invention eliminates the need to stop an image sensor on an optical film for imaging of a plurality of polarization states when measuring the polarization characteristics of an optical film having an area larger than its imaging field of view using a two-dimensional image sensor. In addition, it is an object of the present invention to provide a fast and high polarization characteristic measuring apparatus and method, which makes it possible to carry out without stopping the image sensor even for multiple imaging of the same image to improve the measurement accuracy. It is.

The optical characteristic measuring apparatus of this invention implements at least 4 types of polarization characteristics in a 1st direction by arrange | positioning and arrange | positioning the light transmission means which irradiates a specific polarization illumination to a measurement object, and a wave plate in a 1st direction, An imaging means having an image sensor partitioned into an imaging area for individually imaging the light passing through the wave plate, and scanning means for moving the imaging means relative to the measurement object in the first direction, the scanning means In accordance with the relative movement of the imaging means by the means, each measurement pixel of the measurement object is added to each measurement pixel to obtain an output value obtained by imaging a plurality of times in each imaging area, and the measured value in the imaging area is calculated, and from each imaging area It is characterized by calculating stokes parameters of light for each measurement pixel from the collected measurement values. It is preferable that the said image sensor performs imaging with the imaging element which has many pixels, and outputs one output value for every combined cell which combined several adjacent pixel at the time of imaging. The polarization transmission matrix showing the relationship between the light from the measurement object and the output value output from each imaging area of the image sensor is obtained in units of combined cells before measurement, and the output values output from the polarization transmission matrix and the respective imaging areas are used. It is preferable to obtain the Stokes parameter of the measurement target.

As shown in FIG. 1, since the measurement space resolution is determined as a condition for the measurement of the optical film 12 which is a measurement object, the final measurement result is for every micro area which subdivided the optical film 12 into the magnitude | size of the measurement space resolution. It is a set of measurement results, that is, surface distribution information of optical properties. On the optical film 12 which is a measurement object, it is assumed that there is an area virtually subdivided by the measurement space resolution, and this one area is collectively referred to as "measurement pixel E" after this.

It is preferable that the said image sensor outputs the output value obtained by imaging in unit of a combined cell. The term "combined cell" as used herein refers to the number of imaging cells of an adjacent image sensor vertically and horizontally, which is one large cell (combined cell), and the output value of the cell averages the output values of all the imaging cells included in the combined cell. One value. These combined cells are collectively referred to as "combined cells (CP)" hereinafter.

The reason why imaging is performed in units of a combined cell (CP) is as follows. The graph of FIG. 2 shows the deviation of the output value at the time of using a 12-bit output CCD camera as an image sensor. This graph inputs relatively bright light (light whose output value is close to 3740) for a combined cell in which a predetermined number of pixels are combined, and simply performs 256 measurements to plot a deviation width obtained by subtracting the minimum value from the maximum value of all the output values. It is. In this graph, the vertical axis represents the deviation of the output value of the CCD camera, and the horizontal axis represents the number of combined cells representing the number of combined pixels. Here, for example, a combined cell having four combined cells has two vertical pixels and two horizontal pixels. In addition, in FIG. 2, the black circle | round | yen shows the deviation width (measurement result) of the output value of a CCD camera, and the dotted line has shown the approximation curve obtained from the black circle | round | yen. From this result, it is understood that the noise accompanying the output of the CCD camera is proportional to almost -1/2 power of the number of combined cells, and thus there is a characteristic of random noise.

As this graph shows, 1 cell, 4 cells, 9 cells, 16 cells,... Each time the cell size (number of combined cells) is increased, the variation in the output value of the CCD camera is reduced. Therefore, if the number of combined cells is not increased to some extent, the variation in the output value of the CCD camera is large. Therefore, measurement cannot be performed with high accuracy unless the number of images is increased and averaged. In addition, the CCD used for obtaining this graph is 1 / 1.8 inch, 2 million pixels, and an imaging cell size is 4.4 micrometer square.

The number of pixels constituting the combined cell CP is 1, 4, 9. The number of sequences of N ² (N is a natural number) starting from 1 is preferable, and the maximum value is a combined cell in which the measurement spatial resolution (that is, the size of the measurement pixel E) of an object to be imaged on the image sensor is combined. It is assumed to be the size of.

The imaging part 15 is shown in FIG. Here, although the example which used CCD as an image sensor is shown, CMOS may be sufficient as an image sensor. The wavelength plate has shown the example which used four sheets by implementing one kind of polarization characteristic with respect to one sheet. The number of wave plates is not limited to only four types as described later. The structure of the imaging unit 15 includes a camera case 40, a CCD camera 41, a telecentric lens 42, a CCD camera rotating mechanism 43, and first to fourth wavelength plates 45. -48 and the polarizing plate 49 are provided. The camera case 40 has a substantially rectangular parallelepiped shape, and one opening 40a (refer FIG. 4) for mounting the 1st-4th wavelength plates 45-48 and the polarizing plate 49 is formed. In this camera case 40, the CCD camera 41, the telecentric lens 42, and the CCD camera rotation mechanism 43 are formed. In addition, the CCD camera rotating mechanism 43 is for adjustment purpose of matching one direction of the two-dimensional array of the coupling cells with the scanning direction of the scanning means. In addition, the arrow X in FIG. 3 has shown the relative movement direction of the measurement object (it may move either a measurement object or an imaging part).

The telecentric lens 42 uses a bilateral telecentric lens and an object side telecentric lens. The telecentric lens 42 forms an image of a measurement object in a size multiplied by the lens magnification on a CCD (the magnification is one to one third to one third). Because of the telecentric lens's depth of focus and its ability to capture luminous flux parallel to the optical axis, the light transmitted through each waveplate arrives at the image sensor without mixing with each other, forming a separate area corresponding to each waveplate. do. Each area on the CCD substantially divided by the wave plate generated by the light beams passing through the respective wave plates is collectively referred to as "imaging area".

How arbitrary one measurement pixel E on the optical film 12 passes through the 1st-4th wavelength plates 45-48, and is measured by the imaging part 15 is demonstrated using FIG. . In addition, in FIG. 4, in order to make the description clear, the reduction or enlargement effect in the telecentric lens 42 and the inverted image forming effect are not included in the figure, and on the optical film 12 One point is equally magnified on the CCD 55 and drawn to form an image.

First, when any measurement pixel E on the optical film 12 enters the visual field of the imaging part 15 by a scanning means, the light emitted from the measurement pixel E is initially made into a 1st wavelength plate ( Enter the compartment of 45) and briefly traverse this compartment. Since the first wavelength plate 45 is formed by the action of the telecentric lens 42 and formed in the imaging area 50 corresponding to the CCD 55, the measurement pixel E is formed in the first wavelength plate 45. While traversing the section of, the image of the measurement pixel E traverses the section of the imaging area 50, and a plurality of imaging is performed in accordance with the movement of the constant distance of the measurement pixel E. Similarly, the 2nd-4th wavelength plates 46-48 are image-formed in the imaging area 51-53, and the measurement pixel E is also image | photographed several times here.

The polarization transfer matrix indicating the relationship between the Stokes parameter of the light incident on the image pickup means and the output value output from the image sensor is obtained in advance in the unit of the combined cell (CR) of the CCD.

The output value of CCD concerning the measurement pixel E obtained by imaging is the matrix product of the Stokes parameter of the light which came out from the measurement pixel E, and the polarization transfer matrix which the coupling cell which imaged it.

Each output value of CCD concerning the measurement pixel E obtained by imaging is added for every imaging area, and it takes out as a measured value in the imaging area. At the same time, the matrix summation of the polarization transfer matrix of the coupling cell CR used in the imaging of the measurement pixel E is also performed for each imaging area. In this way, the relational expression of the measured value, the Stokes parameter of light, and the polarization transfer matrix with respect to the measurement pixel E is obtained by the number of imaging regions (or the number of types of polarization states embodied). Since there are four types of measured values which are the number of imaging areas, the Stokes parameter can be calculated from this. By performing this process for every measurement pixel E, the surface distribution information of the Stokes parameter of a measurement object is computed.

It is preferable that the image sensor is picked up over two coupling cells in which predetermined measurement pixels are adjacent to each other. The output value of the predetermined measurement pixel is multiplied by the ratio of the pixel which picked up the predetermined measurement pixel of one coupling cell to the output average value of the pixel, and the pixel which is picked up the predetermined measurement pixel among the other coupling cells. It is preferable that the ratio is multiplied by the output average value of the pixel.

The moving means moves at least either one of the measurement target or the imaging means in the first direction, and at least each time the imaging of the first direction of the measurement target by the imaging means is completed. It is preferable to move either one in a second direction perpendicular to the first direction and parallel to the measurement object.

When the said moving means moves at least one of a measurement object or an imaging means to a 2nd direction perpendicular to a 1st direction and parallel to a measurement object, the positional relationship in the 2nd direction of an imaging means and a light projection means It is preferable to move while maintaining ie, that is, move so that a change in positional relationship does not occur, and to make the polarization irradiation width of the light transmitting means narrow so that the viewing width in the second direction of the imaging means can be irradiated.

It is preferable that the number of polarization types implemented by the said wave plate is 4-40. It is preferable that the said wave plate has the same ground effect as the wave plate whose ground amount is 70 degrees-170 degrees, or 190 degrees-290 degrees.

The optical characteristic measuring method of this invention arrange | positions and arranges a wavelength plate in a 1st direction, implement | achieves at least 4 types of polarization characteristics in a 1st direction, and also image | photographs which image | photographs the light which permeate | transmitted the said wavelength plate separately. Using an imaging means having an image sensor partitioned into areas, the imaging means is moved relative to the measurement object in the first direction so that each measurement pixel of the measurement object is imaged a plurality of times in each imaging area. It is characterized by adding and calculating the measured value in the imaging area for each measurement pixel, and calculating the Stokes parameter of the light emitted from the measurement object for each measurement pixel from the measured values collected in the same manner from each imaging area.

According to the present invention, at least four kinds of wave plates having different polarization characteristics are arranged in the first direction, and the imaging means comprises four imaging areas of the wave plates for individually imaging the light transmitted through each of the wave plates. Since, is used, each measurement pixel on the measurement target is continuously performed during the relative movement of four or more kinds of polarization measurement imaging with the movement in the first direction with respect to the imaging means of the measurement target. In addition, in one imaging area, each measurement pixel is imaged a plurality of times by different measurement pixels, and since the polarization transfer matrix of each measurement pixel is measured in advance, the real average processing is performed as the multiple measurement of the same measurement. It is possible to improve the S / N ratio. In this manner, four or more types of polarization state measurement and multiple imaging can be simultaneously achieved while moving the imaging means relative to the measurement object without stopping. After completion of the movement of the measurement object in the first direction (that is, measurement completion), the measurement surface can be widened by moving the imaging object in the second field of view width, so that the moving image in the first direction and the second direction are moved. By repeating the movement of, the entire surface of the measurement object can be measured. Since four or more types of polarization states are measured, the measurement stokes parameter can be determined. By comparing the Stokes parameter of a light source with the measured Stokes parameter, the polarization characteristic of a measurement object can be calculated.

Thus, according to this invention, the polarization characteristic of an optical film of a large area can be measured quickly and with high precision. For example, what used about 10 minutes in the conventional method on the conditions of 1 mm square space resolution and 0.1 degree of axial direction measurement precision can be measured in about 2 and a half in this invention. That is, according to the present invention, it is possible to achieve about four times faster speed as compared with the conventional method.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the measurement pixel of the optical film which is a sample.
Fig. 2 is a graph showing the relationship between the number of combined cells and the deviation of the output value of the CDD camera (data near 3740/4096, which is high luminance in the camera having an output value of 12 bits).
3 is a schematic view of an imaging unit.
It is explanatory drawing for demonstrating image pick-up of the measurement pixel E in the 1st-4th imaging area of a CCD camera.
5 is a schematic view of an optical property measuring apparatus of the present invention.
6 is a flow chart showing the operation of the present invention.
It is explanatory drawing explaining the translucent pixel of a surface illumination part.
8 is a schematic view showing a light and an imaging unit used to obtain a polarization transfer matrix.
Fig. 9 is a schematic diagram showing a two-dimensional array structure of one element in a storage area having an XY address used for calibration measurement and measurement.
FIG. 10: is explanatory drawing for demonstrating image pick-up of the measurement pixel E1 by each coupling cell in the 1st imaging area of a CCD camera.
FIG. 11: is explanatory drawing for demonstrating image pick-up of the measurement pixel E1 by each coupling cell in the 2nd-4th imaging area of a CCD camera.
FIG. 12: is explanatory drawing for demonstrating storing the output value obtained by imaging of the measurement pixel E1-En in 1st-4th memory | storage part E11-En4.
FIG. 13: is explanatory drawing for demonstrating the case where the combined cells CP11 and CP12 image the measuring pixel E1 in the ratio of 7: 3.
14 is an explanatory diagram for explaining that the measurement pixel E1 is imaged 11 times in the coupling cells CP11 to CP15.
FIG. 15 is an explanatory diagram for explaining the case where the combined cells CP11 and CP12 pick up the measurement pixel E1 at a ratio of 5: 5.
Fig. 16 is a graph showing the relationship between the ground level and the calculation error amount of a wave plate to be used.
Fig. 17 is a table showing the relationship between the ground level and the calculation error amount of a wave plate to be used.
18 is a schematic view showing an image capturing unit in which first to fourth wave plates are formed directly in front of a CCD camera.
It is a schematic diagram of the measuring apparatus produced by making a lighting part thin.
20 is a schematic view showing a measuring device including two CCD cameras.

As shown in FIG. 5, the optical characteristic measuring apparatus 10 of this invention measures the optical film 12 which has a predetermined | prescribed birefringent characteristic as a measurement object. In the optical characteristic measuring apparatus 10, the optical film 12 which is a measurement target is placed on the surface illuminating part 14 attached to the sample stage 13. And the optical film 12 is illuminated with the illumination of the circularly polarized light emitted from the surface illuminating part 14, and the sample stage 13 is moved to the X direction by the imaging part 15 with the light emitted from this optical film 12. I take a picture while making it. And the computer 16 calculates the optical characteristic of the optical film 12 by performing various analyzes based on the output value obtained by the imaging part 15. Moreover, you may use elliptical polarization as polarized light illumination.

The sample stage 13 is movable in the X direction along the two rails 22a and 22b on the base 22 by the X-direction moving mechanism 20. Moreover, the X direction movement mechanism 20 is comprised with the servo motor which drives based on the drive pulse output from the X motor driver 24. As shown in FIG.

Similarly, the imaging part 15 is attached to the arm 31 formed in the support stand 30. The arm 31 is movable in the Y direction orthogonal to the X direction by the Y direction moving mechanism 33, and is orthogonal to the X direction or the Y direction by the Z direction moving mechanism 34. It is possible to move in the Z direction. As the arm 31 moves in the Y direction or the Z direction as described above, the imaging unit 15 can also be moved in the Y direction or the Z direction. In addition, the purpose of the movement in the Z direction is for focus adjustment of the imaging unit 15. The Y direction movement mechanism 33 drives based on the drive pulse output from a Y motor driver (not shown).

The drive pulses from the X motor driver 24 and the Y motor driver are also transmitted to the X pulse counter 26 and the Y pulse counter (not shown), respectively. Each pulse counter counts received drive pulses. The value counted by the pulse counter is sent to the computer 16. Since the computer 16 stores the movement amount of the sample stage 13 and the movement amount of the imaging unit 15 per pulse, the field of view of the imaging unit 15 is determined from the count value of both pulse counters. Find out where you are on the table.

Next, the operation of the present invention will be described with reference to the flowchart of FIG. 6. First, it is measurement preparation to perform at the beginning, and here, the polarization transfer matrix of the imaging part 15 is specified in the unit of the coupling cell CP of the CCD camera 41. This operation is performed only once as an initial setting. The obtained polarization transfer matrix is stored in the computer 16, and after the initial setting, the obtained polarization transfer matrix is used.

Calibration preparation is carried out after measurement preparation. Here, the Stokes parameters (hereinafter referred to as S parameters) of the light emitted from the surface illuminating unit 14 are measured in units of measurement resolution over the entire surface of the surface illuminating unit 14.

It is assumed that the surface illuminating unit 14 as the light transmitting means has an area virtually subdivided into units of measurement resolution as shown in FIG. 7, and these areas are collectively referred to as "light emitting pixels L". Is called. Therefore, calibration measurement is a process of calculating | requiring an S parameter by the transmissive pixel unit L. FIG.

It is not necessary to carry out the calibration measurement as long as there is no fluctuation in the light source, but it is generally preferable to carry out at the first measurement of one day.

It is a real measurement to perform after calibration measurement, and here, the S parameter of the light which transmits the optical film 12 on the surface illumination part 14 and passes through the optical film 12 is over the whole surface of the optical film 12. Measured in units of measurement resolution (ie measurement object E).

Finally, the birefringence characteristic of the measurement object is calculated by comparing the S parameter obtained by the actual measurement with the S parameter of the illumination unit. What is important here is that the counter of the measurement target stage is used by matching the position of each measurement pixel E in the actual measurement with the position of each light-emitting pixel L in the calibration measurement. Since the current value of the counter indicates where the respective combined cells of the camera capture the measurement target stage, the output value of each combined cell obtained at the time of measurement is accurately measured for each of the projection pixels L or each measurement pixel. It can distribute to (E).

Below, it describes in full detail from a measurement preparation process. The measurement preparation step is a step of specifying the polarization transfer matrix of each coupling cell of the CCD camera used for the imaging unit 15 of the present apparatus before the actual measurement. The measuring mechanism itself used for this specificity may be inserted into the apparatus, the polarization transfer matrix measurement may be performed externally from the apparatus, and only data may be input to the computer 16 using a USB memory or the like. .

The reason for obtaining the polarization transfer matrix of the imaging unit 15 in the unit of the combined cell of the CCD camera 41 is to average the measured values obtained from the plurality of measurement pixels E in the same wavelength plate section, and to measure 1 in the wavelength plate. This is to obtain a representative highly reliable measurement value. Even light having passed through the same wavelength plate section cannot be treated in the same way because they are measured values using different parts of the wavelength plate, the polarizing plate, the telecentric lens, and different measurement pixels of the CCD. This is because there is a variation (locality) of local polarization transfer characteristics in each. However, if a polarization transfer matrix is obtained for each combined cell unit in advance, the influence of locality can be corrected from a plurality of measured values, and a representative representative measured value with high reliability can be arranged.

The polarization transfer matrix is a matrix showing the relationship between the S parameter of the light incident on the imaging unit 15 and the output value output from the CCD camera 41. This polarization transfer matrix can be determined from the product of a Mueller matrix (hereinafter, referred to as M matrix) such as an optical member forming the imaging unit 15. The M matrix associated with any coupling cell on the CCD includes the M matrix of the light beam passing portion of any of the wave plates 45 to 48 through which the light beam incident on the coupling cell passes, and the light beam passing portion of the polarizing plate 49. M matrix of M, the M matrix of the light beam passing portion of the telecentric lens, and the M matrix of the combined cell of the CCD. Equation 1 shows the general form of this M matrix. The x mark is an element that does not need to be specified because it is not related to subsequent calculations.

If only the first row of the M matrix is taken out and normalized to the M ₁₁ element, Equation 2 is obtained. This matrix is defined as the polarization transfer matrix in the combined cell.

Again M ₁₂ / M ₁₁ , M ₁₃ / M ₁₁ , M ₁₄ / M ₁₁ Is replaced with the symbols M ₁₂ , M ₁₃ , and M ₁₄ familiar to the M matrix, and M ₁₁ is replaced with the coefficient K to obtain Equation 3.

The matrix of the format shown in [Equation 3] is a general symbol representing the polarization transfer matrix in the combined cell. Here, K is a proportional coefficient of the polarization transfer matrix, but this value also includes the shading effect of the CCD camera (variation in the quantum efficiency and gain coefficient of each coupling cell of the CCD camera 41).

In the measurement preparation process, as shown in FIG. 8, the polarization transfer matrix is calculated | required individually for every coupling cell of the imaging part 15 using the light 70 whose S parameter is known. Here, the light 70 whose S parameter is known is obtained by transmitting the parallel light from the parallel monochromatic light source 72 to the polarizing plate PL1 and the quarter wave plate QWP1 in the reference light projector 71. . The orientation of the polarizing plate PL1 is fixed, and the transmission axis is arranged at 0 degrees with the reference direction of the orientation in the imaging unit 15 as 0 degrees. The quarter wave plate QWP1 has a motor-driven continuous rotation mechanism (not shown), which is used by continuously rotating it in the measurement of the polarization transmission matrix. The actual ground amount and the axial orientation of the wave plate QWP1 are known, and the fast axis orientation is also defined by setting the reference orientation in the imaging unit 15 as 0 °.

The known light 70 is a light beam around the optical axis center of the reference light projector 71. The polarization transfer matrix of one combined cell is measured by one measurement. The reference light projector 71 is used by using the XY moving mechanism 71a of the reference light projector 71 so that the optical axis center of the light beam of the reference light projector 71 passes through the center of the coupling cell which is the measurement target of the imaging unit 15. ) And the imaging unit 15 are made to face each other. When the polarization transfer matrix measurement of one coupling cell is completed, the polarization transfer matrix measurement of the side measurement pixel is performed using the XY shift mechanism 71a. In this way, the polarization transfer matrix of all the coupling cells of the imaging unit 15 is measured.

Here, the known S parameter of the light 70 is | P ₀ P ₁ P ₂ P ₃ | to a ^T, will be described a method of measuring the polarization transfer matrix of any one of the combination cell. The signal output value of this coupled cell and the S parameter of the light 70 used for the measurement have a relation of [Equation 4] when the polarization transmission matrix of this coupled cell is described by [Equation 3].

When each element of the S parameter of the light 70 is described in detail using the constant of QWP1, it is represented by the following formula (5).

Here, the orientation of QWP1 is γ, and the phase difference is ε, C = cos2γ, and S = sin2γ.

K 'is a coefficient for matching with the output value of the actual CCD camera 41, and is a real number determined during this measurement.

From the above, P ₀ , P ₁ , P ₂ , and P ₃ are represented by the following formula (6).

Substituting [Equation 6] into [Equation 4], [Equation 7] is obtained.

When DFT (Discrete Fourier Transformation) is performed in the azimuth γ of QWP1 with respect to [Equation 7], as shown in [Equation 8], four relational expressions representing the output values of the DC component and the following frequency component are obtained. Where Fdc is the direct current component, Fcos4 is the cos4γ component, Fsin4 is the sin4γ component, and Fsin2 is the measured amplitude of the sin2γ component.

It is to be noted that Fdc is added with the dark current of the CCD (any CCD outputs an arbitrary value even with zero light amount). When this value is set to BG, the subtraction of BG from Fdc in [Equation 8] is the direct current component to be used for the subsequent calculation, and the equation 4 in [Equation 8] is modified to [Equation 9]. The BG can be specified by completely blocking the light of the CCD camera, and obtains this value in advance.

In the four equations shown in [Equation 9], since the unknowns are four of K · K ′, M ₁₂ , M ₁₃ , and M ₁₄ , a value is obtained. For example, M ₁₂ can be specified from (1) ÷ (2), K · K 'can be specified subsequently, and M ₁₃ and M ₁₄ can be specified thereafter.

In this way, all elements of the polarization transfer matrix of one coupling cell and the value of K · K 'can be specified. By repeating this in all the coupling cells CP, the polarization transfer matrix and the values of K · K 'in all the coupling cells CP of the imaging unit 15 can be specified. Among the values of K · K ', K is a value different for each coupling cell, but K' is a value related to the intensity of light used in the present measurement preparation and can be regarded as constant during this measurement. Therefore, the value of K * K 'specified here can be used as a relative signal intensity ratio between each coupling cell in subsequent measurement (calibration measurement, real measurement). In the subsequent measurement, even if the intensity of light may be different from the measurement of the measurement preparation, this value can be used as the relative signal intensity ratio between each coupling cell.

Here, each element of the polarization transfer matrix in each specific coupling cell CP is stored in the computer 16. At this time, the value of K · K 'specified here is referred to by the symbol K again in the following description.

In this way, since the wavelength plate, the polarizing plate, the lens, and the CCD are measured collectively as a polarization transfer matrix after being woven, there is no need to specify one by one. This brings about a great advantage of reducing the load on the measurement.

Next, the detail of a calibration measurement and a real measurement is described (refer to the flowchart of FIG. 6). The operation is completely the same in both cases, and the point of measurement is that the surface illuminator 14 is the calibration measurement, and the optical film 12 is the actual measurement. Hereinafter, the actual measurement will be described as an example.

Calibration measurement and actual measurement also form a temporary output value storage area in the computer 16 to store the output value of the CCD. This output value storage area is an array distinguished by the two-dimensional address of XY in the measurement stage of the measurement pixel E, and one array element corresponds to the number of wave plates and one wave plate as shown in FIG. It is a two-dimensional structure which is distinguished by the number of measurements in it, and has a four-dimensional structure as a whole.

In the calibration measurement and the actual measurement, the sample stage 13 is first moved from one end to the other end in the X direction while the imaging unit 15 is stopped at a predetermined position in the Y direction. When the sample stage 13 moves, an imaging trigger is issued and imaging is automatically performed. On the sample stage 13, there is a surface illuminating portion 14 and an optical film 12 (hereinafter, simply referred to as an "optical film 12"), and the image capturing portion 15 is provided to the other end of the optical film 12 or the like. When imaging is performed, since the measurement of the field of view width of a camera is complete | finished, in order to change a camera field of vision, this time, the imaging part 15 moves the field of view width for Y direction. Then, it moves to the other end from the other end, such as the optical film 12 again, and image | photographs the non-image part, such as the optical film 12. The above procedure is repeated, and the imaging of the whole optical film 12 etc. is performed.

The process from the imaging until the S parameter is calculated below is shown. In addition, since CCD captures all the pixels simultaneously at the imaging timing, data is acquired from all the combined cells by one imaging, but the following description focuses on one measuring pixel E as a representative example. In addition, in order to simplify description, it is assumed that five coupling cells CP are arranged in the X direction in each imaging area 50 to 53 of the CCD camera 41 so that an image of the measurement pixel E as an object is displayed. It demonstrates by arbitrary 1 cross section of the X direction passing through. Here, the measurement pixel E is set to be equal to the size of the coupling cell CP on the CCD. This setting can be adjusted by setting the magnification of the telecentric lens or the number of combined cells.

As shown in Fig. 10 (a), the five first coupling cells formed in the first imaging area 50 are CP11 to CP15, and the five second coupling cells formed in the second imaging area 51 are CP21 to CP5 is set as CP25, the five 3rd coupling cells formed in the 3rd imaging area 52 are CP31-CP35, and 5th 4th coupling cells formed in the 4th imaging area 53 are CP41-CP45. Moreover, let the measurement pixel of the optical film 12 be E1-En (n is a natural number of 2 or more). And the interval of the imaging trigger which fires when the optical film 12 is moved to an X direction is the length L of the X direction of a coupling cell on the CCD (the X direction in = 1 measurement pixel). Length). Since five coupling cells are arranged in the X direction in each imaging area of the CCD, when one measurement pixel E passes through each imaging area, five imaging operations are performed in each imaging area.

First, as the optical film moves in the X direction, the image of the measurement pixel E1 arrives on the first coupling cell CP11 of the first imaging area at an arbitrary timing. And as shown in FIG.10 (b), when the image of the measurement pixel E1 is located on the 1st coupling cell CP11, the 1st coupling cell CP11 picks up the measurement pixel E1. The output value obtained by this imaging is stored in the output value storage area EM1 for the measurement pixel E1 in the computer 16. EM1 is a two-dimensional array as shown in Fig. 9, where the row direction is the number of imaging areas and the column direction is the number of measured values. This output value is stored in the row EM11 for the first imaging area of the output value storage area EM1.

Next, when the optical film 12 moves in the X direction by the amount of movement of one imaging trigger, the image of the measurement pixel E1 of the optical film 12 is located on the first coupling cell area CP12. The first combined cell area CP12 picks up the measurement pixel E1. The output value obtained by this imaging is stored in the other area | region of the row EM11 for the 1st imaging area of the output value storage area EM1 for the measurement pixel E1. In the same manner, the measurement pixel E1 is imaged in the first coupling cell areas CP13 to CP15, and the output value obtained by the imaging is stored in EM11. Therefore, when the measurement pixel E1 passes through a 1st imaging area, 5 times of image pick-up is performed.

Next, as shown in FIG. 11A, when the measurement pixel E1 reaches the coupling cell CP21 in the second imaging area 51, the coupling cell CP21 picks up the measurement pixel E1. do. The output value obtained by this imaging is stored in the 2nd imaging area row EM12 of the output value storage area EM1 in the computer 16. As shown in FIG. Similarly, imaging is performed every time the measurement pixel E1 passes through the second coupling cells CP22 to CP25, and the output values obtained by imaging are stored in EM12 in order.

And as shown in FIG.11 (b), even when the measurement pixel E1 has passed through 3rd coupling cell CP31-CP35 in the 3rd imaging area 52, it image | photographs similarly. The output value at the time of imaging the measurement pixel E1 in these 3rd coupling cells CP31-CP35 is memorize | stored in the row EM13 for 3rd imaging area of the output value storage area EM1. In addition, as shown in FIG. 11 (c), even when the measurement pixel E1 passes through the fourth coupling cells CP41 to CP45 in the fourth imaging area 53, the imaging is performed in the same manner, and the output value is It is stored in the fourth row for imaging area EM14 of the output value storage area EM1.

And the measurement pixel E1 passes through the 4th coupling cell CP45 in the 4th imaging area 53, and the measurement with respect to the measurement pixel E1 is completed. In the measurement pixel E2 positioned one backward with respect to the advancing direction of the measurement pixel E1, although the measurement operation starts one time late for the imaging trigger with respect to the measurement pixel E1 and ends later, the same content is performed. All. Further, the measurement pixels E3, E4, E5, ... En positioned further to the rear end are further imaged by shifting the imaging trigger one more time. Each of these output values is stored in the output value storage areas EM21 to EMn4 for the measurement pixels E2 to En corresponding to the output value storage areas EM11 to EM14 shown in FIGS. 10 to 11. The correspondence relationship is shown in FIG.

Next, the method of calculating | requiring the S parameter in the measurement pixel E1 from the output value of the measurement pixel E1 memorize | stored in the output value storage area EM1, and the polarization transfer matrix of the coupling cell specified by the measurement preparation process is shown. .

When obtaining the S parameter in the measurement pixel E1, first, as shown in the following Equation 10, the sum of the output values obtained by imaging in the first to fourth imaging areas, that is, EM11 to EM14, respectively. The sum of the five output values stored in _S11-? To _S14- ? Is obtained. In the present invention, the sum of such output values is called a measured value, and S is denoted with a _Σ subscript. In addition, the first number 1 attached to S as S11 to S14 is a number for identifying the measurement pixel, and, strictly speaking, it will be a group of numbers corresponding to the two-dimensional address, but in this case, it corresponds to 1 of E1. The second numerals 1 and 4 correspond to the imaging areas 1 to 4, and are the numbers of the wave plates used for the measurement. The subscripts of _A1 to _A5 indicate that the measurement order in one imaging area, that is, the first measurement to the fifth measurement result.

On the other hand, the coupling cells CP11 to CP45 each have their own polarization transfer matrix, and this value is specified by the measurement preparation step. If the polarization transfer matrices of CP11 to CP45 are written down in order in accordance with the definition, it becomes [Equation 11].

Here, numbers such as the subscript _CP11 are numbers for distinguishing the combined cells.

In this example, the output value S11 _{_ CP11} ~ S14 _{_ CP45} is coupled cell because the separately measured in (CP11 ~ CP45), as shown in Equation 12 below, the polarization transfer matrix to the measurement of the coupled cells S parameter of the pixel E1 | S0 _{_ E1} S1 _{_ E1} S2 _{_ E1} S3 _{_ E1} | that would be defined by a matrix multiplication of ^T. Here, the subscript _E1 indicates that it is the S parameter of the measurement pixel E1.

Here, by substituting the definition of the output value of [Equation 12] into the measured value _{S11_Σ} of [Equation 10] and arranging it by the S parameter, [Equation 13] is obtained.

In this Equation 13, the measured value _{S11_Σ} is a form in which certain coefficients are multiplied by the respective S parameter elements. These coefficients multiply and sum the known value already specified in the measurement preparation process. Here, as shown in [Equation 14], this coefficient group is defined under the name of known quantity. The known quantity can be precalculated and can be treated as one numerical value after that.

The first number of known quantity subscripts shows the element number of the S parameter to be a coefficient, and the second number is a number for distinguishing the wave plate. _N is a subscript that distinguishes the position in the Y direction of the coupling cell. However, in this example, since one cross section is handled in the X direction, the value represents the arbitrary cross-sectional position. By substituting [Equation 14] into [Equation 13], the following [Equation 15] is obtained.

It is possible to apply the same processing to measure _{_Σ} S12 ~ S14 _{_Σ} measure of [Equation 10] and [equation 16] can be obtained.

The four equations combined with [Equation 15] and [Equation 16] can be solved because the unknown number is four of the S parameters and the number of equations is four. Thereby, the S parameter in the measurement pixel E1 is calculated | required.

As described above, the state in which one measurement pixel E1 is sequentially picked up by the coupling cells arranged in the X-direction on the CCD on which an image is formed, and finally the S parameter is calculated. Since the CCD captures all the pixels simultaneously, the same processing is performed simultaneously while all the combined cells capture the measurement pixel E somewhere on the optical film 12 while the above processing is performed. . In the whole CCD, it has the processing capability of the combined cell in a visual field.

In this way, the S parameter in all the measurement pixels E can be calculated | required similarly to the method of obtaining the S parameter in the measurement pixel E1. The obtained S parameter is stored in the actual measurement S parameter storage area in the computer 16 in accordance with the XY address of the measurement pixel E.

In the case where the measurement is a calibration measurement, instead of the measurement pixel E, the S parameter of the entire light-emitting pixel L of the surface illumination unit 14 is measured. The S parameters of all the light-emitting pixels L are stored in the S parameter storage area for calibration measurement in the computer 16.

In addition, since the XY address of the measurement pixel E and the XY address of the light emitting pixel L are determined at the position of the sample stage when the imaging trigger is issued, as a result, the light emission is performed with the measurement pixel E having the same XY address. Pixel L becomes a positional relationship which overlapped up and down. In addition, the light that illuminates the measurement pixel E can be regarded as irradiated from the light-transmitting pixel L of the same XY address by the function of selectively replenishing the deep focal depth of the telecentric lens and the component of light parallel to the optical axis. have.

In addition, since the computer 16 can specify beforehand which position of the sample stage 13 to issue an imaging trigger, the numerical value of a known quantity can be calculated beforehand. This has the effect that it is very advantageous for speeding up the processing in applications that need to process a large amount of measurement data called two-dimensional measurement.

Finally, the calculation method of the polarization characteristic of the optical film 12 is shown. The computer 16 is based on the S parameter of the whole surface illumination part 14 calculated | required by the calibration measurement, and the S-axis direction and the retardation of the whole optical film whole surface based on the S parameter of the whole surface of the optical film 12 calculated | required by actual measurement. To calculate. The S parameter of the light transmitted from any measurement pixel E of the optical film 12 is | 1 Φ Ψ ξ | ^T , and the S parameter of the light emitted by the light-transmitting pixel L directly below E is | 1 XYZ | ^{When set to T} , the birefringent principal axis orientation α and the ground amount δ of the optical film 12 corresponding to the measurement pixel E can be expressed by Equation 17.

Here, S = sin2α and C = cos2α. By using this relational formula, the polarization characteristic distribution of the optical film 12 can be measured by a sample resolution by calculating the birefringence principal axis orientation α and the ground amount δ of all the measurement pixels E of the optical film 12.

In addition, although description of this embodiment was made to image | photograph 5 times in total in each imaging area, you may image 5 times or more, for example, 10 times in order to improve measurement accuracy. In this case, as shown below, it is performed by overlapping imaging (partly overlapping one imaging visual field and the next imaging visual field).

Overlap imaging is performed by making the movement amount of the sample stage between 1 imaging triggers into the length L of the X direction of a measurement pixel or less. In the case of setting such a shift amount, since one measurement pixel is imaged over two adjacent coupling cells, distribution of output values is necessary. For example, FIG. 13 is a state of 2nd imaging in the example of FIG. 10 when the movement amount between 1 imaging trigger is set to 3/10 of L. FIG. At this imaging timing, the measurement pixel E1 is located on a 7/10 area of the coupling cell CP11 and is located on a 3/10 area of the coupling cell CP12. In this case, the SUB coupling cell is defined. The SUB coupling cell is an integer multiple of 1/10 of the coupling cell (CP) and the Y direction is the same size as the coupling cell, and the output average of the imaging cells of the CCD included in the SUB coupling cell is determined by the SUB coupling cell. Set it as an output value. In FIG. 13, a SUB coupling cell of CP11 is formed in an area of 7 (represented by diagonal lines), and a SUB output value S11 _{_ CP11} is formed as an output value thereof, and a SUB coupling cell of CP12 is formed in an area of CP12 (represented by diagonal lines). As the output value, the SUB output value S11 _{_CP12} is generated, and each is stored in EM11. In addition, the output value at this time is handled as being comprised with the content shown by [Equation 18].

In FIG. 14, the state in the imaging area 50 when the movement amount between 1 imaging trigger is set to 5/10 of L, and the state of the SUB coupling cell at the time of 3rd imaging are shown in FIG. The measurement pixel E1 is imaged 11 times in total in CP11-CP15. The definition of the 11 output values is represented by [Equation 19].

The symbols "and" are symbols attached to indicate the difference in measurement timing, and have no other meaning. The calculation of the known quantity in this result yields [Equation 20]. It is 2 times, and it can be interpreted that it is a result which doubled imaging.

The known quantity is corrected by a relational expression such as Equation (18) and (19). Since the imaging timing is determined by the position of the sample stage, it is possible to design in advance which coupling cell CP or SUB coupling cell the measurement pixel E is to be picked up at all imaging timings. The size and known quantity of the combined cell at all imaging timings can be calculated beforehand.

In this way, in each measurement pixel E, data from two SUB combined pixels is distributed for one imaging, but the measured value of one imaging area is still added to the total output value obtained in the imaging area. Can be treated as As a result, the equation of the measured value is combined by the number of wave plate types, and then the birefringence distribution of the measurement object is obtained by the same method as described above.

In the present embodiment, the first to fourth wave plates 45 to 48 are wave plates having a ground amount of approximately 135 °, and the main wave direction (fast axis direction) is the first wave plate 45 in FIG. 3. When the horizontal direction is set to 0 °, the second wave plate 46 is disposed so as to have an axial orientation of approximately 20 °, and the second wave plate 46 is disposed at an orientation in which the axial orientation is approximately 36 ° with respect to the first wave plate 45, and the third The wave plate 47 is disposed in the direction in which the axial direction is further added by approximately 36 ° with respect to the second wave plate 46, and the fourth wave plate 48 is further in the axial direction with respect to the third wave plate 47. Is placed in the orientation added approximately 36 °. In addition, the polarizing plate 49 was arrange | positioned so that a transmission axis might become an orientation of 0 degree. The reason why the term “approximately” is used here is that in the measurement preparation step shown in the flowchart of FIG. 6, the polarization transfer matrix is specified in the unit of the coupling cell (CP) in the imaging unit, and then the polarization transfer matrix is used. This is because rigor becomes unnecessary here. It is usually in the range of ± 0.5 °.

In this example, four types of wave plates are used, but four or more types of wave plates may be used. For example, when using N wavelength plates (N is a natural number of 5 or more), it is preferable that N wavelength plates are arrange | positioned in the form which the principal axis orientation distributes 180 degrees equally. Moreover, as for the ground quantity of each waveplate, about 135 degrees are preferable. If it is such a structure, the main-axis orientation of a 1st wave plate may be arbitrary directions.

The reason for this arrangement is that the error when solving (15) and (16) by the simultaneous equations is minimized. When obtaining the S parameter of light from Equations 15 and 16, the measured value (left side) of each equation includes noise accompanying the output value of the CCD. Although these are reduced by the average effect of multiple imaging, they are not zero, and thus they are included as an error in the resulting S parameter. The amount of noise accompanying the left side of [Equation 15] and [Equation 16] is reflected as an error in the S parameter in the calculation process by the computer 16 is represented by [Equation 15] and [Equation 16]. Determined by the coefficient multiplied by the variable (S parameter). In other words, by calculating the system so as to have an appropriate coefficient, the calculation error (influence of noise of the CCD) of this CCD can be minimized. The choice of this coefficient is just like the specification of the waveplate (the choice of ground quantity and principal axis orientation).

As a result of repeating the simulation, the authors found that: First, it was found that in the case where the ground wave amount was changed using the same waveplate to change the main axis orientation of the installation to realize the change in polarization state, even if the number of waveplates was increased, it did not significantly affect the calculation accuracy. This is because even if the number of wave plates increases, the area of one wave plate becomes small, so that the reliability of the measured value in one wave plate becomes low. In addition, if the type of the wave plate is increased, the combined cell corresponding to the boundary line of the wave plate cannot be used, thereby substantially reducing the light receiving area of the CCD. The reduction in the light receiving area means a decrease in the S / N ratio. On the other hand, when the number of wave plates is large, there is an effect that the cutoff frequency of noise included in the signal can be increased. In consideration of both, it can be said that the minimum value of the number of wave plates is four types required for determining an S parameter, and the maximum value is about 40.

It is preferable that the types of the wave plates differ in the arrangement of the main axis directions by using the wave plates having the same ground level, and the calculation error is the best when the wave plates are arranged with the difference in the directions by the angle divided by the number of wave plates. Smaller. The installation method of such an installation wave plate is hereinafter called equal allocation, and the number of wave plate is called a division number.

On the other hand, in the case where the spacing angle difference between the wave plates is 45 °, the calculation error is increased even if the number of wave plate types is used. In four types of wavelength plates, since the equal allocation angle is 45 °, the equal allocation angle at which the calculation error is the smallest cannot be used. For this reason, the arrangement of this embodiment was chosen.

On the other hand, as shown in FIG. 16 and FIG. 17, the ground quantity of the wave plate showed that there existed the area which the calculation error per 135 degrees becomes minimum with the number of all the wave plates. The angle division of the wave plate orientation is set to equal allocation (but only 4 divisions are 36 ° difference). It was confirmed that this tendency exists in all 4-40 divisions.

Regarding the position of the wave plate, in the present embodiment, the first to fourth wave plates 45 to 48 are formed on the object side of the telecentric lens. Instead, as shown in FIG. The fourth wave plates 45 to 48 may be formed directly in front of the CCD camera. Here, the polarizing plate 49 is formed between the 1st-4th wavelength plates 45-48 and the CCD camera 41. FIG.

In this case, there is an advantage that the wavelength plate can be made small and the cost is lowered. On the other hand, since the telecentric lens comes out of the polarizing plate, there is a disadvantage in that an error in obtaining the birefringence transfer function is increased.

Moreover, in this embodiment, although the method of moving the imaging part 15 to an X direction and a Y direction using the surface illuminating part 14 of the magnitude | size which illuminates the whole surface of the optical film 12 was shown, in FIG. As shown, instead of the surface illuminating part 14, the width is made thin enough to illuminate the view width of the Y direction of the imaging part 15, and when the imaging part 15 moves Y, the lighting part 14 also moves to a Y direction. You may use the illumination part 101 made to make it allow. In this case, the effect of reducing the cost of the surface illuminating unit 14 and shortening the acquisition time of the stokes parameter is obtained. In addition, when the illumination part 101 is used, instead of the sample stage 13, the sample stage 102 in which the opening was formed in the part where the optical film 12 is mounted is used.

In addition, in this embodiment, although the optical characteristic of the whole optical film 12 was measured by moving one CCD camera 41 to an X direction and a Y direction, in order to further shorten a measurement time, several CCD is carried out. You may measure with a camera. In that case, as shown in FIG. 20, one dedicated camera CPU is provided with respect to one camera, and the main CPU which integrates several camera CPU is installed above. The polarization transfer matrix of each coupled cell of the camera is placed on the main CPU side, and each known quantity is calculated in advance. The S parameter storage area for calibration measurement and actual measurement is also placed in the main CPU. The output value storage area for storing the measurement results of each camera is also placed on the main CPU side, but a duplicate (replica) of the output value storage area is prepared on the camera CPU side. And with the movement to the X direction of a measurement stage, each CCD camera repeats imaging. The camera CPU calculates the output value in units of combined cells (SUB combined cells in some cases) and stores them in the duplicate (replica) side of the output value storage area. When the imaging in the X direction reaches the scanning end, the Y movement of the field of view of each camera and the movement of the sample stage to the scanning starting end in the X direction are performed, but imaging is performed during this movement. Since the camera CPU does not have an imaging load. Using this load, the camera CPU copies data from the copy of the output value storage area to the output value storage area on the main CPU side. The main CPU detects a copy of the data in the output value storage region, calculates and stores the S parameter, and calculates the polarization characteristic of the optical film. Since the main CPU deviates from the imaging load even during imaging of the CCD camera, most of the CPU power can be divided into this calculation. As described above, the camera CPU and the main CPU can be operated efficiently, and the effect of speeding up the process by increasing the number of cameras is obtained.

In the present embodiment, in the calibration measurement and the actual measurement, the imaging start and end are not described in detail. However, since not all of the visual fields of the CCD camera are valid at the start and end of the imaging, the output value obtained by imaging at this time is Do not use in post-calculation. In addition, although the boundary line of a 1st-4th wave plate was not described in detail, when the imaging of the measurement pixel E was performed on the boundary line of a 1st-4th wave plate, the output value obtained by this imaging is a post-mortem. Do not use in calculations. This is because it is possible to exclude information at unnecessary positions of the sample stage because the position detecting means always specifies where each coupling cell of the CCD captures the sample stage 13. Moreover, since the coupling cell in the position where the joint of a wave plate forms is also known beforehand, it becomes possible not to use this part.

In addition, in this invention, although imaging was performed by the combined cell unit which combined the several imaging cell which adjoined, if imaging cell size is big enough and there seems that there is no problem of noise, you may image by unit of imaging cell.

10: optical characteristic measuring device
12: optical film
13: sample stage
14: surface lighting
15: imaging unit
16: Computer
20: X direction moving mechanism
33: Y direction moving mechanism
41: CCD camera
45-48: 1st-4th wave plate
50-53: 1st-4th imaging area
55: CCD
CP1 to CP4: first to fourth coupling cells

Claims (10)

Light transmitting means for irradiating a specific polarized light to a measurement target, and a wave plate aligned in a first direction to realize at least four types of polarization characteristics in the first direction, and separately transmitting light transmitted through the wave plate. An imaging means having an image sensor partitioned into an imaging area for imaging with a scanning area; and scanning means for moving the imaging means in the first direction relative to a measurement object, and for relative movement of the imaging means by the scanning means. Accompanying, the measurement value obtained by imaging each measurement pixel in the imaging area several times in each imaging area is added to every measurement pixel, and the measured value in the imaging area is calculated, and the measurement value collected from each imaging area is calculated for each measurement pixel. An optical characteristic measuring apparatus characterized by calculating a stokes parameter of light. The method of claim 1,
The image sensor performs imaging with an imaging device having a plurality of pixels, and at the time of imaging, outputs one output value for each combined cell in which a plurality of adjacent pixels are combined. 3. The method according to claim 1 or 2,
The polarization transmission matrix showing the relationship between the light from the measurement object and the output value output from each imaging area of the image sensor is obtained in units of combined cells before measurement, and the output values output from the polarization transmission matrix and the respective imaging areas are used. And obtaining a Stokes parameter of a measurement target. The method according to claim 2 or 3,
The image sensor is an optical characteristic measuring device, characterized in that the predetermined measurement pixel is picked up over two adjacent coupling cells. 5. The method of claim 4,
The output value of the predetermined measurement pixel is multiplied by the ratio of the pixel which picked up the predetermined measurement pixel of one coupling cell to the output average value of the pixel, and the pixel which is picked up the predetermined measurement pixel among the other coupling cells. The optical characteristic measuring apparatus which consists of multiplying a ratio and the output average value of the pixel. 3. The method according to claim 1 or 2,
The moving means moves at least either one of the measurement target or the imaging means in the first direction, and at least each time the imaging of the first direction of the measurement target by the imaging means is completed. An optical property measuring apparatus, which is moved either in a second direction perpendicular to the first direction and parallel to the measurement object. The method according to claim 6,
When the said moving means moves at least one of a measurement object or an imaging means to a 2nd direction perpendicular to a 1st direction and parallel to a measurement object, the positional relationship in the 2nd direction of an imaging means and a light projection means Moving, keeping the polarization irradiation width of the light transmitting means narrow so that the viewing width in the second direction of the imaging means can be irradiated. 3. The method according to claim 1 or 2,
The number of polarization types embodied by the said wave plate is 4-40, The optical characteristic measuring apparatus characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The said wave plate has the same ground effect as the wave plate whose ground amount is either 70 degrees-170 degrees, or 190 degrees-290 degrees. Having an image sensor partitioned by an imaging area arranged to align the wavelength plates in the first direction to realize at least four types of polarization characteristics in the first direction, and to separately image the light passing through the wavelength plate. By using the image pickup means, the image pickup means is moved relative to the measurement target in the first direction, and each measurement pixel of the measurement target is added to an output value obtained by imaging a plurality of times in each imaging area, and in each imaging pixel in the imaging area. And a stoke parameter of light emitted from the measurement target for each measurement pixel from the measurement values collected in the same manner from each imaging area while calculating the measurement value of.

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