JP2008111916A - Objective lens for polarization observation and microscope having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens having high polarization characteristic for reducing isogyre in order to solve a problem wherein polarization light made incident on the objective lens having a spherical lens in a conventional microscope causes rotation of vibration plane due to a difference in transmittance characteristic between P polarization and S polarization, and furthermore, this phenomenon depends on the location of a lens through which light passes, leading to so-called isogyre in which the pupil face of the objective lens does not become dark completely, with the result that the background of an observation area becomes bright, making it difficult to observe, and to provide a microscope that has this objective lens. <P>SOLUTION: The objective lens includes at least two cylindrical lenses disposed so that their curvature directions are perpendicular to each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technical field of lenses, and relates to an objective lens having excellent polarization characteristics and a microscope using the objective lens.

  In the microscopic observation, observation using the polarization characteristic of the sample is very common. For example, it is used for observation of rock crystal structure and gout inspection. In addition, there is an observation method called fluorescence polarization observation that combines fluorescence observation and polarization observation. This observation involves the difficulty of detecting particularly weak observation light, but it captures molecular movements in the sample. It is an advanced observation technique that can

  Polarization in the optical system is discussed by decomposing it into P-polarized light in which the vibration plane of the electric field coincides with the incident plane such as the optical plane and S-polarized light in which the vibration plane of the electric field is perpendicular to the incident plane. The reason is that characteristics such as transmittance and reflectance are different between P-polarized light and S-polarized light, and this difference greatly affects polarized light observation. For example, when linearly polarized light enters an optical element such as a lens, a phenomenon is known in which the vibration surface rotates due to a difference in transmittance characteristics between P-polarized light and S-polarized light.

Here, the polarization change caused by the lens as described above will be described with reference to FIGS. 1A, 1B, and 1C. Here, a spherical lens is considered as the lens in FIG.
In FIGS. 1A, 1B, and 1C, it is assumed that the linearly polarized light 1 advances from the back of the paper surface to the front surface, assuming that the spherical lens is the paper surface. At this time, OE is the vibration plane (polarization plane) of the linearly polarized electric field, and OH is the vibration plane direction of the magnetic field. At this time, a circle indicated by 4 in FIG. 3 is a concentric circle with the center O of the spherical lens, and a light incident surface incident on the spherical lens is a surface including the radial direction of the circle 4 and the optical axis. That is, linearly polarized light having a vibration plane in the tangential direction of the circle 4 is S-polarized light, and linearly polarized light having a vibration plane in the normal direction is P-polarized light.

  FIG. 1A shows a state of polarized light immediately before linearly polarized light enters the spherical lens. The polarized light at the point M at this time is linearly polarized light 5 whose vibrations are aligned in the OE direction. An enlarged view of the linearly polarized light 5 at the point M at this time is referred to as an enlarged view Z. As shown in the enlarged view Z, the linearly polarized light 5 at the point M can be regarded as the sum of the S-polarized light component 6 and the P-polarized light component 7.

  FIG. 1B shows the state of polarized light when linearly polarized light passes through the spherical lens. In FIG. 1B, after passing through the spherical lens, the linearly polarized light at point M, which was linearly polarized light in the OE direction, is changed to linearly polarized light having a different vibration surface due to the difference in transmittance characteristics between P polarized light and S polarized light. . An enlarged view of the linearly polarized light 5 at the point M at this time is referred to as an enlarged view Z. As shown in the enlarged view Z, the linearly polarized light 5 ′ before passing through the spherical lens is regarded as the sum of the S-polarized component 6 and the P-polarized component 7 and is multiplied by the transmittance for each component (in FIG. Therefore, the case where the transmittance of the P-polarized component is approximately 100% is illustrated). As a result, the linearly polarized light 5 transmitted through the spherical lens shifts the vibration surface in the normal direction of the concentric circle 4.

  Next, FIG. 1C shows a state of polarized light when passing through an analyzer (analyzer) arranged in crossed Nicols after the vibration surface is rotated. Since the analyzer is arranged so as to transmit only the polarization component in the OH direction, all the polarized light should be shielded. However, as described above, since the linearly polarized light 5 transmitted through the spherical lens at the position such as the point M is rotated on the vibration surface, the polarization component 8 of the portion where the vibration surface of the light is changed by the rotation passes through the analyzer 3. Resulting in.

  The above becomes a big problem in a polarizing microscope. The light beam that has passed through the polarizer passes through several lenses, especially an objective lens that combines multiple lenses, and as described above, the plane of vibration of linearly polarized light rotates little by little as it passes through the lens. Go. At this time, since the objective lens has many lenses, it greatly affects the rotation of the polarization vibration plane. As can be seen from the above principle, it has a great influence on the four oblique directions on the pupil plane of the objective lens.

  The above phenomenon is known as isogyre in the pupil plane. As shown in FIG. 2, this phenomenon is a phenomenon in which bright areas remain in diagonal directions. This phenomenon brightens the background light for polarization observation, making it difficult to detect the observation light from the sample.

  As a method for solving this problem of isogyre, there is a conventional method called a rectifier. The principle of the rectifier is that a simple optical element having almost the same polarization characteristics as that of the microscope optical system is inserted in the optical path between the polarizer and the analyzer, and a half-wave plate is placed in front of the optical element. A method of reversing the vibration surface of the light passing through the optical system and then canceling it by the above-described element is performed. This method can reduce the above-mentioned isogyre.

However, in this rectifier, it is necessary to place a spherical lens after the light passes through the objective lens, and there is a problem that the imaging performance deteriorates greatly to compensate for the rotation of the vibration surface of the light generated by the objective lens. there were. Further, it has been difficult to compensate the rotation of the vibration plane of polarized light by the objective lens only with the rectifier after passing through the objective lens. For example, in the case of a transmissive illumination system, compensation can be made by increasing the effect of the condenser lens side rectifier, which does not affect the imaging performance, but on the other hand, when the degree of polarization of the fluorescent substance is measured with high accuracy In this case, it is necessary to compensate for the rotation of the vibration plane of the polarization of the light only by the rectifier after passing through the objective lens, and the imaging performance is deteriorated by arranging many rectifiers. In addition, when a rectifier is used, there is a problem that a space including the rectifier is required and the configuration of the optical system becomes large.
Japanese Patent No. 2886230 JP 11-72710 A

  Polarized light incident on an objective lens having a spherical lens of a conventional microscope causes rotation of the vibration surface due to the difference in transmittance characteristics between P-polarized light and S-polarized light. Moreover, this phenomenon depends on the position of the lens through which the light beam passes. Therefore, the pupil plane of the objective lens is not completely dark, and so-called isogyre occurs. This isogyre has a problem that the background of the observation area becomes bright and observation is difficult. An object of the present invention is to provide an objective lens having high polarization characteristics for reducing isogyre and to provide this objective lens in a microscope.

  The objective lens of the above-mentioned subject of the present invention can be solved by including at least two cylindrical lenses arranged so that the curvature directions are orthogonal. By arranging the cylindrical lenses so that the curvature directions are orthogonal, rotation of the vibration plane of linearly polarized light can be suppressed. At this time, it is desirable that the cylindrical lens includes two lenses closest to the specimen surface. Since the lens closest to the sample surface has a large refractive power, the present invention can be effectively implemented by using two lenses closest to the sample surface as cylindrical lenses. In addition, it is desirable that the objective lens according to the embodiment of the present invention includes a concave cylindrical lens. A concave cylindrical lens is effective in correcting various aberrations in a microscope objective lens.

  In addition, a microscope using the objective lens according to the present invention has a polarizer that converts illumination light from a light source into linearly polarized light, a condenser lens that transmits the illumination light converted into linearly polarized light into the sample, and the sample that is transmitted from the sample. This is realized by including the objective lens that expands the transmitted observation light and the analyzer that transmits only a polarized component of the transmitted observation light emitted from the objective lens. With this configuration, a transmission illumination type polarization microscope having excellent polarization characteristics is provided. In this case, the condenser lens may be configured to include at least two cylindrical lenses arranged so that the curvature directions are orthogonal. With this configuration, it is possible to suppress the rotation of the plane of vibration of linearly polarized light in the condenser lens.

  In addition, the microscope using the objective lens according to the present invention irradiates the sample with the polarizer that converts the illumination light from the light source into linearly polarized light, and the illumination light converted into the linearly polarized light, and collects the reflected observation light. This is realized by including the objective lens and an analyzer that transmits only a certain polarization component of the reflected observation light emitted from the objective lens. With this configuration, an epi-illumination type polarization microscope having excellent polarization characteristics is provided.

  The microscope using the objective lens according to the present invention irradiates a sample with a polarizer that converts excitation light from a light source into linearly polarized excitation light, and excitation light converted into linearly polarized excitation light. This is realized by including the above-described objective lens that collects emitted fluorescence and an analyzer that transmits only a polarized component of fluorescence emitted from the objective lens. With this configuration, a fluorescence polarization microscope having excellent polarization characteristics is provided.

  Here, it is desirable that the objective lens according to the present invention is installed so as to be rotatable with respect to the optical axis. With this configuration, the curvature direction of the cylindrical lens in the objective lens can be matched with linearly polarized light.

  Further, it is necessary that at least two of the objective lens, the polarizer, and the analyzer according to the present invention are rotatably installed. Further, when a cylindrical lens is also used as the condenser lens, it is necessary that at least three of the objective lens, the condenser lens, the polarizer, and the analyzer according to the present invention are rotatably installed. With these configurations, appropriate preparation for polarization observation can be performed.

  By providing the polarizing microscope with the objective lens having high polarization characteristics according to the present invention, it is possible to reduce isogyr caused by birefringence of the objective lens provided in the polarizing microscope, which has been a problem in the past. That is, since the background of the observation field can be darkened, even weak observation light can be detected.

  In the present invention, an objective lens including at least two cylindrical lenses as an objective lens having high polarization characteristics and a microscope including the objective lens are provided for the purpose of reducing isogyre.

  Embodiments of the present invention will be described below with reference to the drawings.

  A configuration example and a principle of an objective lens including a plurality of cylindrical lenses according to the present invention and arranged so that the curvature directions of the respective cylindrical lenses are orthogonal to each other will be described with reference to FIGS. 3A and 3B.

  The objective lens according to an embodiment of the present invention shown in FIG. 3A is composed of six cylindrical lenses 11, 12, 13, 14, 15, and 16, which are adjacent to each other. It is shown in the cross section. Here, the upper diagram in FIG. 3A is a sectional view in the curvature direction of the cylindrical lenses 11, 13, and 15, and the lower diagram in FIG. 3A is a sectional view in the curvature direction of the cylindrical lenses 12, 14, and 16.

  FIG. 3B illustrates a case where the linearly polarized light 18 is transmitted through the cylindrical lens. In the figure, it is assumed that the cylindrical lens has a curvature in the direction of the axis R, and the vibration plane of the linearly polarized light 18 is parallel to the axis R. At this time, the linearly polarized light 18 at each of the points M, M ′, and M ″ is P-polarized light. In addition, when there is a curvature in the direction of the axis F, all are S-polarized light. That is, since the cylindrical lens has only one direction of curvature, when one curvature direction of two cylindrical lenses whose curvature directions are orthogonal to each other is aligned with the polarization vibration direction, the other curvature direction is Inevitably, the direction of polarization is orthogonal to the direction of polarization oscillation, and the polarization plane does not rotate.

  Therefore, by incorporating a cylindrical lens into the optical element of the objective lens, rotation of the polarization plane of linearly polarized light passing through the objective lens can be suppressed. That is, it is possible to prevent isogyre on the pupil plane and reduce background light. At this time, the cylindrical lens of the objective lens must be coincident with or orthogonal to the incident plane of linearly polarized light. Therefore, it is desirable that the objective lens is attached so that it can be rotated according to the incident polarization plane. Further, since the cylindrical lenses have refractive power only in one direction, it is desirable that the cylindrical lenses are configured in pairs. In other words, it is desirable to use at least two cylindrical lenses for the objective lens in the practice of the present invention. Of course, all of the optical elements of the objective lens can be constituted by cylindrical lenses.

  When a cylindrical lens is used as a part of the lens in the objective lens, its arrangement should be considered in order to effectively implement the present invention. In general, the difference in transmittance between S-polarized light and P-polarized light becomes significant when the incident angle between the polarization plane and the optical surface is small. In other words, this situation often occurs when the refractive power of the lens is large. From this, it can be said that the effect is great when a lens having a large refractive index is replaced with a cylindrical lens. In general, since the lens closest to the specimen surface of the objective lens has a large refractive power, it is effective to replace this lens with two cylindrical lens pairs.

  Further, when the objective lens according to the embodiment of the present invention is used for a microscope, it is preferable to use a concave cylindrical lens. The objective lens of the microscope has a configuration using a concave lens for correcting various aberrations. The refractive power at the concave lens is generally large. Therefore, it is effective to use this concave lens as a cylindrical lens.

  As shown in FIG. 3A upper and FIG. 3A lower, it is desirable to make the cylindrical lens closest to the specimen surface concave. This is to suppress the amount of aberration generated when the light beam coming from the sample surface is bent. Moreover, it is desirable that there are a plurality of concave surfaces in both cross sections as shown in FIG. This is to facilitate correction of various aberrations of the objective lens by the negative refractive power of the concave surface.

FIG. 4 shows an overall schematic diagram of a transmission illumination type polarization microscope configured to include an objective lens including the cylindrical lens of the present invention as one embodiment of the present invention.
In the following, the optical configuration and principle of a polarization microscope including an objective lens including the cylindrical lens of the present invention will be described with reference to FIG.

  4 includes a light source 21 for illuminating a sample, a collector lens 22 for converting illumination light from the light source into substantially parallel light, and illumination light. Reflecting mirror 23, field lens 24 that creates a primary image of light source 21, polarizer 25 that makes linearly polarized light through polarized light having a specific vibration plane, condenser lens 26 that connects the primary image of the light source and the sample in relation to the pupil position, sample Stage 27, sample 28 to be observed, objective lens 29 equipped with the cylindrical lens of the present invention, analyzer 30 for making linearly polarized light through polarized light having a specific vibration plane, and imaging for condensing polarized light that has passed through the analyzer The lens 31 and the image pickup device 32 that records the formed image are configured.

  The principle of the microscope of this embodiment will be described below. The illumination light that has passed through the polarizer 25 is converted into linearly polarized light having a specific vibration surface. After that, the illumination light irradiated to the sample 28 on the stage 27 through the condenser lens 26 is changed in the vibration direction of the linearly polarized light incident due to the polarization property and birefringence of the sample 28. This transmitted light is incident on the objective lens 29.

  At this time, the linearly polarized light and the cylindrical lens in the objective lens 29 are arranged so that their curvature directions coincide or are orthogonal to each other. With this arrangement, the observation light can be transferred to the analyzer 30 while accurately maintaining the polarization characteristics of the sample 28. Since the analyzer 30 and the polarizer 25 are arranged in a crossed Nicols relationship, the light detected by the imaging device 32 is only due to the polarization characteristics of the sample 28.

In the above configuration, the polarizer 25, the objective lens 29, and the analyzer 30 need to have the same angle. That is, at least two of the three need to be rotatably installed.
In the above configuration, the condenser lens 26 is also disposed between the polarizer 25 and the analyzer 30. That is, also in the condenser lens 26, the vibration plane of the linearly polarized light is rotated. Therefore, the condenser lens 26 may be formed of a cylindrical lens as with the objective lens 29. At that time, it is necessary to adjust all the angles of the polarizer 25, the condenser lens 26, the objective lens 29, and the analyzer 30, and at least three of the four must be rotatably installed.

  In FIG. 5, the whole structure of the epi-illumination type | mold polarization microscope comprised including the cylindrical lens of this invention as one embodiment of this invention is shown. The optical configuration and principle of an epi-illumination polarization microscope that includes the cylindrical lens of the present invention will be described below with reference to FIG.

  An epi-illumination type polarizing microscope including an objective lens having a cylindrical lens of the present invention in FIG. 5 includes a light source 41 for illuminating a sample, a collector lens 42 for converting illumination light from the light source into substantially parallel light, and a light source 41. A field lens 43 for creating a primary image, a polarizer 44 for making linearly polarized light through polarized light having a specific vibration plane, a half mirror 45 for reflecting illumination light to the objective lens, a stage 48 for placing a sample, a sample 47 to be observed, a book The objective lens 46 having the cylindrical lens of the invention, the analyzer 49 that converts the polarized light having a specific vibration plane into linearly polarized light, the imaging lens 50 that collects the polarized light that has passed through the analyzer, and the imaging that records the image formed It is constituted by the element 51.

  The principle of the microscope of this embodiment will be described below. The illumination light that has passed through the polarizer 44 is converted into linearly polarized light having a specific vibration surface. Thereafter, the illumination light applied to the sample 47 on the stage 48 through the objective lens 46 is changed in the vibration direction of the linearly polarized light that is incident due to the polarization property and birefringence of the sample 47. This reflected light is incident on the objective lens 46 again.

  At this time, the linearly polarized light and the cylindrical lens in the objective lens 46 are arranged so that their curvature directions coincide or are orthogonal to each other. With this arrangement, the observation light can be transferred to the analyzer 49 while accurately maintaining the polarization characteristics of the sample 47. Since the analyzer 49 and the polarizer 44 are arranged in a crossed Nicols relationship, the light detected by the image sensor 51 is only due to the polarization characteristics of the sample 47.

  In the above configuration, the polarizer 44, the objective lens 46, and the analyzer 49 need to have the same angle. That is, at least two of the three need to be rotatably installed.

  In FIG. 6, the whole structure of the epi-illumination type | mold fluorescence polarization microscope comprised including the cylindrical lens of this invention as one embodiment of this invention is shown. The optical configuration and principle of the epi-fluorescence polarization microscope that includes the cylindrical lens of the present invention will be described below with reference to FIG.

  The epi-illumination fluorescence polarization microscope including the objective lens having the cylindrical lens of the present invention in FIG. 6 includes a light source 61 that generates light having a wavelength for exciting a phosphor in a sample, and substantially parallel light as excitation light. Collector lens 62, a field lens 63 that creates a primary image of the light source 61, a polarizer 64 that makes linearly polarized light through polarized light having a specific vibration plane, an excitation filter 65 that selectively passes light of a specific spectrum, a specific A dichroic mirror 66 that selectively reflects light in a spectrum to separate excitation light and fluorescence, a stage 68 on which a sample is placed, a sample 69 to be observed, an objective lens 67 having a cylindrical lens of the present invention, and a specific excitation light spectrum A filter 70 for removing light, an analyzer 71 for converting linearly polarized light through polarized light having a specific vibration plane, and an analyzer 7 An imaging lens 72 to the polarization condenses light passing through the, an imager 73 for recording the imaged image.

  In FIG. 6, the positional relationship between the polarizer 64 and the excitation filter 65, and the analyzer 71 and the barrier filter 70 are interchangeable. In a general microscope, the excitation filter 65, the dichroic mirror 66, and the barrier filter 70 are provided as a unit. However, considering the influence of the polarization characteristics of the excitation filter 65 and the barrier filter 70, it is desirable that the polarizer 64 is downstream of the excitation filter 65 and the analyzer 71 is disposed upstream of the barrier filter 70.

  The principle of the microscope of this embodiment will be described below. The excitation light that has passed through the polarizer 64 is converted into linearly polarized light having a specific vibration surface. Thereafter, the linearly polarized light of the excitation light is applied to the sample 69 on the stage 68 through the excitation filter 65 and the objective lens 67. At this time, fluorescence is emitted from the phosphor in the sample. However, it is known that the fluorescence is also polarized when the excitation light is polarized. However, when the phosphor has a molecular motion or the like, the degree of polarization decreases according to the speed. Using this phenomenon, the fluorescence polarization microscope can observe the movement of the substance in the sample.

  In this way, the fluorescence in the form of polarized information is incident on the objective lens 46 again. At this time, since the wavelengths of the excitation light and the fluorescence are different from each other, the excitation light and the fluorescence are separated from the excitation light by the dichroic mirror 66, and only the fluorescence having the necessary wavelength is selected by the barrier filter 70. The light that finally passes through the analyzer 71 is only the polarization component generated by the degree of polarization being weakened by the movement of the phosphor in the sample.

  At this time, the linearly polarized light and the cylindrical lens in the objective lens 67 are arranged so that their curvature directions coincide or are orthogonal to each other. With this arrangement, the observation light can be transferred to the analyzer 49 while accurately maintaining the polarization characteristics of the fluorescence emitted from the sample 69. The analyzer 64 and the polarizer 71 must be arranged in a crossed Nicols relationship.

  As described above, the objective lens having high polarization characteristics and the polarization microscope including the same are described. Although the present invention has been described with reference examples as specific embodiments, it is apparent that various modifications and changes can be made to these embodiments without exceeding the scope or concept of the invention. It is. Accordingly, the specification and figures are to be regarded as illustrative rather than in a restrictive sense.

It shows the state of polarization when the illumination light enters the spherical lens after passing through the polarizer. It shows the state of polarization when illumination light passes through a spherical lens after passing through a polarizer. It shows the polarization state when the illumination light passes through the spherical lens after passing through the polarizer and then passes through the analyzer arranged in crossed Nicols. It is a schematic diagram of the isogyr produced with a polarization microscope. It is a figure of the objective lens and imaging lens containing a cylindrical lens. As one embodiment of the present invention, a state of polarization when illumination light passes through a cylindrical lens after passing through a polarizer is shown. As one embodiment of the present invention, an overall configuration of a transmission illumination type polarization microscope including an objective lens including the cylindrical lens of the present invention is shown. As an embodiment of the present invention, an overall configuration of an epi-illumination type polarization microscope including the cylindrical lens of the present invention is shown. As an embodiment of the present invention, an overall configuration of an epi-illumination type fluorescence polarization microscope including the cylindrical lens of the present invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polarized light 2,25,44,64 ... Polarizer 3, 30, 49, 71 ... Analyzer 4 ... Concentric circle 5 ... Linearly polarized light, elliptically polarized light 6 ... S polarized light component 7... P polarization component 10, 18... Linearly polarized light 11, 12, 13, 14, 15, 17... Cylindrical lens 16, 31, 50, 72. .. Light source 22, 42, 62 ... Collector lens 23 ... Mirror 24, 43, 63 ... Field lens 26 ... Condenser lens 27, 48, 68 ... Stage 28, 47, 69 ... Sample 29, 46, 67 ... Objective lens 45 ... Half mirror 51, 73 ... Imaging element 65 ... Excitation filter 66 ... Dichroic mirror 70 ... Barrier filter

Claims (10)

  An objective lens comprising at least two cylindrical lenses having only one direction of curvature, and arranged so that the two directions of curvature are orthogonal to each other.   The objective lens according to claim 1, wherein the two lenses closest to the specimen surface are the cylindrical lenses.   The objective lens according to claim 1, wherein the cylindrical lens includes a concave cylindrical lens. A polarizer that converts illumination light from a light source into linearly polarized light;
A condenser lens that transmits the illumination light converted into linearly polarized light through the sample;
The objective lens according to any one of claims 1 to 3, wherein the transmission observation light transmitted from the sample is enlarged.
A microscope comprising: an analyzer that transmits only a certain polarization component of the transmitted observation light emitted from the objective lens.   The microscope according to claim 4, wherein the condenser lens includes at least two cylindrical lenses arranged so that the curvature directions are orthogonal to each other. A polarizer that converts illumination light from a light source into linearly polarized light;
The objective lens according to any one of claims 1 to 3, wherein the sample is irradiated with the illumination light converted into linearly polarized light and the reflected observation light is collected.
A microscope comprising an analyzer that transmits only a polarized component of the reflected observation light emitted from the objective lens. A polarizer that converts excitation light from a light source into linearly polarized excitation light;
The objective lens according to any one of claims 1 to 3, wherein the sample is irradiated with the excitation light converted into linearly polarized excitation light, and fluorescence emitted from the sample is collected.
A microscope comprising an analyzer that transmits only the polarized component having fluorescence emitted from the objective lens.   The microscope according to any one of claims 4 to 7, wherein the objective lens is installed so as to be rotatable with respect to an optical axis.   The microscope according to claim 4, wherein at least two of the objective lens, the polarizer, and the analyzer are rotatably installed.   The microscope according to claim 5, wherein at least three of the objective lens, the condenser lens, the polarizer, and the analyzer are rotatably installed.