JP2008032969A - Polarizing microscope equipped with polarizing imaging camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscopic system with camera, which acquires polarizing information and optical anisotropic information on an object to be observed by a microscope at the frame rate of an imaging device. <P>SOLUTION: The polarizing microscope is characteristically provided with the polarizing imaging camera in which the array or the like of polarizers composed of a self-cloning photonic crystal, or a wire grid, is installed in front of the imaging device such as a CCD. By concurrently providing a device constitution for regulating the polarizing state of irradiating light for an observation sample, the detailed analysis of the optical characteristic of the observation object is achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical microscope that can acquire and analyze polarization information in more detail than a conventional polarizing microscope.

  A polarization microscope is used for the purpose of observing an observation object composed of a transparent substance, such as a living cell, under a microscope. This uses the refractive index change or birefringence of the object to be observed, and is used when it is desired to observe living cells without staining.

Sato et al., Autumn Meeting of Applied Physics Society 7pZR-14

  Although the image observed with a conventional polarizing microscope or the like reflects the birefringence of the object to be observed, it is an image affected by multiple factors such as the wavelength dispersion of the optical characteristics of the object to be observed. It was. Therefore, it is difficult to use this for detailed quantitative analysis, and it is often limited to applications for which only observation is intended.

  As a means for solving this problem, a polarization microscope system using a liquid crystal element has been commercialized by the company Cambridge Research & Instrumentation, Inc. (CRi) under the trade name Polscope PolScope. However, this product requires an operation to rotate the alignment of the liquid crystal once in order to acquire the polarization information of the image, and therefore it takes several seconds. Therefore, for example, it has been extremely difficult to acquire polarization information of an observation object that moves at high speed.

  The present invention is characterized in that by attaching a polarization imaging camera to a conventional microscope unit, it is possible to observe and quantitatively evaluate optical features such as an optical anisotropy axis direction and a phase change amount of an observation object at high speed. Involved in microscope systems.

  The polarization imaging camera is a region-dividing polarizer array produced by a self-cloning photonic crystal having a different orientation or a polarizer having a metal line on a thin line or thin ribbon (hereinafter referred to as a wire grid polarizer). Alternatively, it is possible to quantitatively analyze the in-plane distribution of the polarization state of a captured image (by the principle of Non-Patent Document 1) by disposing at least one of the wave plate arrays in front of an image sensor such as a CCD or CMOS. It is a featured camera. Alternatively, an in-plane distribution of polarization information can be obtained from the captured image by installing a polarizer in front of each image sensor of an imaging unit that captures simultaneously with three or more image sensors using a half mirror such as a prism. A camera characterized by being able to do so may be used.

  Since it is possible to arbitrarily set the polarization state of the irradiation light in the microscope, the irradiation light is defined in an arbitrary polarization state, and compared with the quantitative evaluation of the in-plane polarization distribution of the observation image, Optical features such as the birefringence axis orientation and the phase difference amount of the observation object can be quantitatively evaluated in detail.

By using an optical microscope equipped with the polarization imaging camera, the in-plane distribution of the optical features to be observed can be acquired at the imaging speed of the imaging device. For example, if an image sensor capable of capturing 30 images per second is used, it is possible to acquire a moving image of polarization information at 30 frames per second, and if 10,000 high-speed image sensors are used per second, It is possible to obtain a polarization information moving image of 10,000 frames per second.
Therefore, by using the optical microscope of the present invention, it is possible to observe the state in which an observation object having optical anisotropy is moving at high speed, and the progress of a chemical reaction that is completed instantaneously is in-plane distribution of polarization information. It is possible to analyze from the time change of.

This function is particularly important in microscope technology. The above-mentioned Polscope is excellent in observing the minute structure of a living body, and can observe the main axis and birefringence phase difference of the microstructure like a chromosome at the time of cell division in a living form by using birefringence, but it is responsive and simultaneous. You can write in sex. For the first time, the present invention makes it possible to measure the main axis and birefringence phase difference of micro birefringence that is responsive, and is extremely effective as a research tool in bioscience, for example.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of the configuration of an optical microscope equipped with a polarization imaging camera. In the microscope shown in FIG. 1, the light collected and horizontally output by the condenser lens 12 in the lamp house 11 is bent upward by a mirror 13 at the bottom of the microscope and passes through a polarizer 14 and a quarter-wave plate 15. Then, the condenser lens 16, the observation sample 17, and the objective lens 18 are passed in this order. Then, a polarization image is obtained on the monitor screen of the computer 20 via the polarization imaging camera 19.

  Light that irradiates the observation sample passes through the polarizer 14 and the quarter-wave plate 15 in this order, and is converted into circularly polarized light or elliptically polarized light that is close to circularly polarized light. Accordingly, even when the birefringence of the observation sample is small, it becomes easy to detect the birefringence azimuth by the difference in the principal axis direction of the polarized light.

  FIG. 2 shows an example of the component configuration of the light receiving unit of the polarization imaging camera used in the present invention. A polarizer having a uniform transmission axis azimuth is disposed in an area of one or more pixels of the image sensor, and an array element in which a plurality of polarizers are disposed and the image sensor are integrated. The intensity of light transmitted through at least three polarizer regions with uniform transmission axis orientation is acquired by the image sensor, and the average polarization information of the region used for the calculation is obtained by comparing and calculating these. Obtainable.

  The arrayed polarizer can be produced from a self-cloning photonic crystal. Moreover, it can produce using a wire grid type | mold polarizer, and any form may be sufficient as it.

Further, any of a configuration having an arrayed wave plate element in addition to the arrayed polarizer and a polarization imaging camera realized by a configuration having an arrayed wave plate and a uniform polarizer may be used.

1. Polarization Imaging Camera In order to implement the optical microscope unit of the present invention, a polarization imaging camera having a polarizer array with self-cloning photonic crystals was used. This polarization imaging camera has a polarizer array in which polarizers of four kinds of transmission axis directions are laid in a region corresponding to one pixel of a 1 million pixel CCD, and calculates the luminance value of four adjacent pixels. Thus, this 4 can obtain the average polarization information of the region. The polarization imaging camera is connected to a personal computer via a USB cable 20 and can display or calculate polarization information on the monitor screen.

2. Microscope Configuration FIG. 3 shows the configuration of an optical microscope equipped with the polarization imaging camera implemented. In the microscope of FIG. 3, the light collected and horizontally output by the condenser lens 12 in the lamp house 11 passes through a bandpass filter 22 that transmits light having a wavelength in the range of 500 nm to 560 nm, and then is reflected by the mirror 13 below the microscope. It is bent upward, passes through the polarizer 14 and the quarter-wave plate 15, and then passes through the condenser lens 16, the observation sample 17, and the objective lens 18 in this order. Then, a polarization image is obtained on the monitor screen of the computer 21 through the polarization imaging camera 19 having the polarizer array 23 and the CCD 24 by the self-cloning photonic crystal.

3. Polarization Information Analysis Light that irradiates the observation sample passes through the polarizer 14 and the quarter-wave plate 15 in this order, and is converted into circularly polarized light or elliptically polarized light that is close to circularly polarized light. Accordingly, even when the birefringence of the observation sample is small, it becomes easy to detect the birefringence azimuth by the difference in the principal axis direction of the polarized light.

  For example, when the irradiation light is circularly polarized light, the luminance information of the four pixels of the CCD that receives the light transmitted through the polarizer region having the transmission axis in four adjacent directions in the observation image is obtained by Fourier transform. Among the average polarization states of the four pixel regions, the principal axis direction of elliptically polarized light indicates the direction rotated 45 degrees from the birefringence axis direction of the observation sample, and the ellipticity indicates the strength of birefringence.

  In addition, when birefringence is distributed over the entire observation image, when the polarization state of the observation sample irradiation light is such that the average of the entire observation image is close to circularly polarized light, the change from the average value of the polarization state is the main axis. It is suitable because it can be detected with high sensitivity as the direction.

  Using the polarization information of starch obtained by the optical microscope system of the present invention, it is possible to color-code according to the principal axis direction of polarized light, and FIG. For comparison, an image with only luminance information is shown in FIG. Irradiation light is circularly polarized light, and a process is performed such that the luminance is lower as it is closer to circularly polarized light in the acquired image. A monochrome image showing the correspondence between the color of the ellipsometric image of FIG. 4 and the direction of the birefringence axis of the observation sample is shown in FIG.

  FIG. 8 shows the result of quantitative analysis of the polarization information of the starch, based on a one-shot polarization image of a CCD with a frame rate of 1/30 second used in this prototype. The horizontal axis of the graph of FIG. 8 represents the position of the thick arrow in the image shown in FIG. 7, the vertical axis 1 represents the change in the principal axis direction of the polarization, and the vertical axis 2 represents the intensity of the polarization. Moreover, the thin arrow in FIG. 7 shows the birefringence axis orientation distribution in the starch which became clear by the analysis. As described above, various information on polarized light, which has been difficult to obtain in the past, can be obtained quantitatively and at high speed.

  The optical microscope system of the present invention can be used in any microscope for the purpose of detecting and observing polarization information and structure of an observation target. In particular, it can be used for the purpose of analyzing in detail the temporal change in the polarization characteristics of the observation object, such as observation of living organisms and liquid crystal materials.

FIG. 1 shows an example of the configuration of an optical microscope equipped with a polarization imaging camera. FIG. 2 shows a component configuration example of the light receiving unit of the polarization imaging camera. FIG. 3 is an apparatus configuration diagram of an embodiment of an optical microscope including a polarization imaging camera in which a bandpass filter is provided between a condenser lens and a mirror. FIG. 4 is a drawing-substituting photograph based on a principal axis orientation image of starch taken with a polarization imaging camera. FIG. 5 is a drawing-substituting photograph based on a comparative image produced using only the same luminance information as that of a normal camera. FIG. 6 is a drawing-substituting photograph showing the relationship between the birefringence axis direction of the material and the display color. FIG. 7 is a drawing-substituting photograph showing a polarized image showing the horizontal axis of the graph of FIG. FIG. 8 is a drawing-substituting photograph showing a graph of polarization information produced from data acquired by a polarization imaging camera.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Lamp house 12 Condensing lens 13 Mirror 14 Polarizer 15 1/4 wavelength plate 16 Condenser lens 17 Observation sample 18 Objective lens 19 Polarization imaging camera 20 Connection cable 21 Computer 22 Band pass filter 23 Polarizer array 24 Image sensor

Claims (5)

At least one of a region-dividing polarizer and a region-dividing wavelength plate that is divided into regions having different transmission axis orientations and regions having different anisotropy axes made of self-cloning photonic crystals is used as a CCD or CMOS. The in-plane distribution of polarization information from the captured image is analyzed from the acquired image of one frame by installing each of the regions in association with one or a plurality of pixels of the image sensor in front of the image sensor such as An optical microscope system equipped with a polarization imaging camera.
An in-plane distribution of polarization information from the captured image can be obtained by installing an area-dividing polarizer having thin line or thin ribbon metal rows divided into areas with different transmission axis orientations in front of an image sensor such as a CCD or CMOS. An optical microscope system comprising a polarization imaging camera, which can be analyzed from an acquired image of one frame.
A polarization imaging camera of a type using a plurality of image pickup devices, in which a light path is divided into three or more by a half mirror such as a prism, and a polarizer and an image pickup device having different transmission axis directions are sequentially arranged for each of them. An optical microscope system characterized by that.
4. The optical microscope system according to claim 1, wherein the polarization state of the irradiation light of the observation sample is uniformly defined.
  By comparing the polarization information of the irradiation light of the observation sample and the polarization information of the observation image, the optical characteristics of the observation target such as the optical anisotropy axis direction and the birefringence phase difference are calculated, and the image display or numerical display is performed. 5. The optical microscope system according to claim 4, wherein the optical microscope system is integrated with a microscope polarization image analysis software having a function capable of performing the function.