JP2006313213A - Optical system for illumination and microscope lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical system for enabling bright phase difference observation and dark field observation by obtaining annular illumination without losing light intensity from a light source, and to provide an illumination optical system for an exposure device and a microscope lighting system using it. <P>SOLUTION: The optical system for illumination comprises a light source 11, a condensing optical system 13 for condensing or dispersing light or making a light flux by condensing light flux dispersed from the light source 11, a doughnut lens 10 for annularly condensing the light flux, an annular opening 2 arranged in the neighborhood of a condensing position of the light flux condensed annularly, and a condenser lens 3 for projecting an image of the annular opening 2 at a pupil position 6 of an observation optical system or projection optical system objective lens 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination optical system and a microscope illumination apparatus, and more particularly to an illumination optical system for a microscope and an exposure apparatus and a microscope illumination apparatus using the same.

  Conventionally, optical systems capable of obtaining annular illumination include those of Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and the like. In the devices described in Patent Documents 1 and 2, the tip of the light guide is formed in a ring shape, and a light beam emitted from the tip of the light guide is irradiated onto the endoscope visual field in a ring shape. In addition, the device described in Patent Document 3 converts parallel light into a conical circularly diffusing light beam with a concentric equidistant diffraction grating, and converges the conical light beam on a ring diaphragm with a converging lens. is there. Further, the device disclosed in Patent Document 4 generates a multiple image of a light source with a special imaging lens so that each light source image of the multiple image is arranged in a circle adjacent to the ring-shaped opening. is there.

A donut-like lens obtained by rotating the shape of a cross section of a convex lens deviating from the central axis within the cross section including the central axis 360 degrees around the central axis in order to convert the parallel light into a conical light beam. Alternatively, Patent Document 5 discloses a technique in which parallel light is incident on an ampang lens (hereinafter referred to as a donut-shaped lens) and condensed in an annular shape.
Japanese Examined Patent Publication No. 5-11284 Japanese Patent Publication No. 5-11285 JP-A-8-334701 JP 2003-270542 A Japanese Patent Publication No. 8-27436

  However, in the above-described optical system capable of obtaining the annular illumination, it has not been possible to uniformly collect light without loss at a sufficiently narrow annular opening (ring diaphragm), or efficient annular illumination has not been achieved.

  In addition, the conventional lens using a donut-shaped lens does not collect light uniformly at the annular opening without any loss.

  The present invention has been made in view of such a situation in the prior art, and an object thereof is to obtain annular illumination without losing the amount of light from the light source, and capable of bright phase difference observation and dark field observation. An illumination optical system, an illumination optical system for an exposure apparatus, and a microscope illumination apparatus using the same.

  The illumination optical system of the present invention that achieves the above object includes a light source, a condensing optical system that condenses the light beam diverging from the light source into a condensed or divergent or parallel light beam, and the light beam in an annular shape. A donut-shaped lens for condensing, an annular aperture disposed in the vicinity of the condensing position of the luminous flux condensed in the annular shape, and an image of the annular aperture for the pupil position of the objective lens of the observation optical system or projection optical system And a condenser lens that projects onto the lens.

  In this case, it is desirable that the donut-shaped lens and the annular zone opening are integrated.

  The donut-shaped lens has a shape that is rotationally symmetric around the optical axis, and has a plano-convex lens shape in which the shape on one side deviating from the optical axis of the cross section including the optical axis faces the convex surface on the light source side. be able to.

  In this case, when the radius from the optical axis at the top of the convex surface is R and the radius of the annular zone opening is r, it is desirable that R≈r.

  Further, it is desirable that the convex surface is a surface whose curvature becomes gentler toward the periphery.

  The donut-shaped lens can be composed of a Fresnel lens.

  Further, it is desirable that the condensing optical system includes a diffusing element that makes the collected light beam uniform.

When the projection magnification from the light source to the light source image in the cross section including the optical axis including the condensing optical system and the doughnut-shaped lens is β,
0.1 <β <20 (1)
It is desirable to satisfy the following conditions.

  Further, the illumination optical system of the present invention described above is used for an illumination device of a microscope having a phase difference observation optical system, and a phase film is arranged in a ring shape at the projection position of the ring zone opening of the phase difference observation optical system. It can be configured as a microscope illumination device.

  Further, the illumination optical system according to the present invention is used in an illumination device of a microscope having a dark field observation optical system, and a condenser having a numerical aperture larger than the numerical aperture of the objective lens of the dark field observation optical system is used. It can be configured as a microscope illuminator that performs dark field illumination by condensing on the sample surface of the dark field observation optical system.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to obtain the illumination optical system and microscope illuminating device which can use illumination efficiently and can perform bright phase difference observation and dark field observation.

  The illumination optical system and microscope illumination apparatus of the present invention will be described below with reference to the drawings.

  First, conventional phase difference observation and dark field observation in a microscope will be described. FIG. 9 is a diagram showing the optical path at the time of conventional phase difference observation after the annular opening. An annular aperture plate 1, a condenser lens 3, and an objective lens 5 are arranged coaxially with the optical axis OO ′, a sample surface 4 is arranged between the condenser lens 3 and the objective lens 5, and an exit pupil 6 of the objective lens 5. A ring-shaped phase film 7 is arranged at a position conjugate with the annular opening 2 of the annular opening plate 1. The light passing through the annular aperture 2 of the annular aperture plate 1 illuminated with parallel light from a light source that has passed through a condensing optical system (not shown) passes through the condenser lens 3 and includes a cross section including the optical axis OO ′. The light is substantially parallel within the (meridional cross section), and the sample on the specimen surface 4 is illuminated as a cone-shaped light beam coaxial with the optical axis OO ′. The light beam transmitted without being diffracted by the sample on the sample surface 4 is incident on the phase film 7 at the position of the exit pupil 6 of the objective lens 5 and is shifted in phase to reach the image surface 8, while the sample on the sample surface 4. Most of the light beam diffracted by the laser beam reaches the image plane 8 without being influenced by the phase film 7, and the two light beams interfere on the image surface 8, so that the phase distribution of the sample can be observed as a contrast image.

  Next, FIG. 10 is a diagram showing an optical path at the time of conventional dark field observation after the annular opening. An annular aperture plate 1, a condenser lens 3, an objective lens 5, and an aperture 9 are arranged coaxially with the optical axis O-O ′, and a sample surface 4 is arranged between the condenser lens 3 and the objective lens 5. The light passing through the annular aperture 2 of the annular aperture plate 1 illuminated with parallel light from a light source that has passed through a condensing optical system (not shown) passes through the condenser lens 3 and includes a cross section including the optical axis OO ′. The light on the specimen surface 4 is illuminated as a cone-shaped light beam in the (meridional section). Since the numerical aperture (NA) of the cone-shaped light beam is configured to be larger than the numerical aperture of the objective lens 5, the light beam transmitted without being scattered by the sample on the sample surface 4 is incident on the objective lens 5. Since it does not enter the pupil, it does not reach the image plane 8. On the other hand, a part of the light scattered by the sample on the sample plane 4 becomes smaller than the numerical aperture of the objective lens 5, and passes through the objective lens 5 and the aperture 9. It reaches the surface 8 and forms a dark field image of the sample on the image surface 8 so that it can be observed.

  However, in both cases of FIG. 9 and FIG. 10, most of the illumination light from the light source illuminates a portion other than the annular opening 2 of the annular opening plate 1 and becomes lost light. I couldn't.

  Next, FIG. 1 shows a layout of the phase difference observation optical system of one embodiment to which the illumination optical system of the present invention is applied. A light source 11, a diffusing element 12, a condensing optical system 13, a donut-shaped lens 10, an annular aperture plate 1, a condenser lens 3, and an objective lens 5 are arranged coaxially with the optical axis OO ′. A specimen surface 4 is disposed between the lenses 5, and a ring-shaped phase film 7 is disposed in a conjugate manner with the annular aperture 2 of the annular aperture plate 1 at the exit pupil 6 position of the objective lens 5. The donut-shaped lens 10 has a rotationally symmetric shape around the optical axis OO ′, and has no power (refractive power) in the sagittal section orthogonal to the meridional section, but has a positive power P in the meridional section. Have. The power P is a reciprocal 1 / f of the paraxial focal length f obtained from a general curvature and refractive index, and the annular aperture 2 of the annular aperture plate 1 is disposed in the vicinity of the focal position of the donut-shaped lens 10. . As the condensing optical system 13, a collector lens or a concave reflecting mirror can be used.

  In such an arrangement, the illumination light emitted from the light source 11, passed through the diffusing element 12, and made substantially parallel by the condensing optical system 13 is incident on the donut-shaped lens 10 and has a ring zone (at the rear focal point in the meridional section). It is condensed in the shape of a ring. Since the condensing position of the illumination light and the annular aperture 2 of the annular aperture plate 1 substantially coincide with each other, almost all of the illumination light emitted from the light source 11 passes through the annular aperture 2 of the annular aperture plate 1, After passing through the condenser lens 3, the light becomes substantially parallel in the meridional section, and the sample on the specimen surface 4 is illuminated as a cone-shaped light beam coaxial with the optical axis OO ′. The light beam transmitted without being diffracted by the sample on the specimen surface 4 is incident on the phase film 7 at the position of the exit pupil 6 of the objective lens 5, is condensed in a ring shape, passes through the phase film 7, and is out of phase. On the other hand, the light beam diffracted by the sample on the specimen surface 4 reaches the image surface 8 without being influenced by the phase film 7 and the two light beams interfere with each other on the image surface 8. The phase distribution of the sample is formed as a contrast image. In order to construct a phase-contrast microscope, the contrast image formed on the image plane 8 can be enlarged and observed with an eyepiece lens, or an intermediate image is projected onto the imaging surface of the image sensor. A lens may be disposed so that the captured image can be displayed on the monitor.

  Next, FIG. 2 shows a layout of the dark field observation optical system of one embodiment to which the illumination optical system of the present invention is applied. A light source 11, a diffusing element 12, a condensing optical system 13, a donut-shaped lens 10, an annular aperture plate 1, a condenser lens 3, an objective lens 5, and an aperture 9 are arranged coaxially with the optical axis OO ′. The specimen surface 4 is arranged between the objective lens 3 and the objective lens 5. The donut-shaped lens 10 does not have power (refractive power) in the sagittal section orthogonal to the meridional section, but has a positive power P in the meridional section. The power P is a reciprocal 1 / f of the paraxial focal length f obtained from a general curvature and refractive index, and the annular aperture 2 of the annular aperture plate 1 is disposed in the vicinity of the focal position of the donut-shaped lens 10. . As the condensing optical system 13, a collector lens or a concave reflecting mirror can be used.

  In such an arrangement, the illumination light emitted from the light source 11, passed through the diffusing element 12, and made substantially parallel by the condensing optical system 13 is incident on the donut-shaped lens 10 and has a ring zone (at the rear focal point in the meridional section). It is condensed in the shape of a ring. Since the condensing position of the illumination light and the annular aperture 2 of the annular aperture plate 1 substantially coincide with each other, almost all of the illumination light emitted from the light source 11 passes through the annular aperture 2 of the annular aperture plate 1, The sample on the specimen surface 4 is illuminated as a cone-shaped light beam coaxial with the optical axis OO ′. Since the numerical aperture of the cone-shaped light beam is configured to be larger than the numerical aperture of the objective lens 5, the light beam transmitted without being scattered by the sample on the sample surface 4 is incident on the entrance pupil of the objective lens 5. Since it does not enter, it does not reach the image plane 8. On the other hand, a part of the light scattered by the sample on the sample plane 4 becomes smaller than the numerical aperture of the objective lens 5, and passes through the objective lens 5 and the aperture 9 to the image plane 8. And forms a dark field image of the sample on the image plane 8. In order to configure the dark field microscope, the dark field image formed on the image plane 8 can be enlarged and observed with an eyepiece, or the intermediate image is projected onto the imaging surface of the image sensor. An image lens may be provided so that the captured image can be displayed on the monitor.

  As described above, in both the phase difference observation optical system and the dark field observation optical system, the donut-shaped lens 10 is disposed on the incident side of the annular zone opening plate 1 so that most of the illumination light from the light source 11 is looped. Since it is used to illuminate the sample through the band opening 2, it is possible to efficiently illuminate the bright annular zone as compared with the conventional cases (FIGS. 9 and 10).

  Here, a ring-shaped condensing state can be obtained with only the donut-shaped lens 10, but since the size of the light source 11 is finite, the diffusion element 12 is arranged behind the light source 11 and the size of the light source 11 is apparently large. It is common to do. Therefore, the ring-shaped condensed image formed by the donut-shaped lens 10 has a certain extent. Therefore, it is important to use it in combination with the ring zone opening 2 for narrowing the ring-shaped condensed image. In order to avoid flare and ghost generated inside and outside the donut-shaped lens 10, it is important to arrange the annular opening 2. In particular, when one side of the donut-shaped lens 10 is configured as a flat surface as shown in FIG. 1 (the rear surface in the case of FIG. 1), the image contrast is adversely affected by repeated reflection with the condenser lens 3. However, it is possible to prevent such repeated reflection by arranging the annular opening 2.

  Here, first, an extended rotation free-form surface is defined. An optical axis OO ′ direction is defined as a Y axis, and a direction orthogonal to the optical axis OO ′ is defined as a Z axis, and passes through the origin on the YZ coordinate plane. The curve (b) is defined.

^{Z = (Y 2 / RY)} / [1+ {1- (C 1 +1) Y 2 / RY 2} 1/2]
C ₂ Y + C ₃ Y ² + C ₄ Y ³ + C ₅ Y ⁴ + C ₆ Y ⁵ + C ₇ Y ⁶
+ ··· + C ₂₁ Y ²⁰ + ··· + C _{n + 1} Y ⁿ + ····
... (a)
Next, the curve (a) is translated in the Z-axis positive direction by a distance R (Z negative direction when negative). At the same time, the coordinate system moves. A curved line obtained by rotating the translated curve in the positive direction of the X axis passing through the origin of the moved coordinate system and rotating counterclockwise is defined as an angle θ (°). A rotationally symmetric surface formed by rotating around the Y axis (optical axis OO ′) of the coordinate system before moving thereafter is defined as an extended rotation free-form surface.

  As a result, the extended rotation free-form surface becomes a free-form surface (free curve) in the YZ plane of the coordinate system before moving, and becomes a circle with a radius | R | in the X-Z plane.

  From this definition, the Y-axis becomes the axis of the extended rotation free-form surface (rotation symmetry axis).

Where RY is the radius of curvature of the spherical term in the YZ section, C ₁ is the conic constant, C ₂ , C ₃ , C ₄ , C ₅ . Aspheric coefficient.

  It is desirable that the donut-shaped lens 10 has an extended rotation free-form surface as described above on at least one surface as shown in a cross section in FIG. In the case of FIG. 3, the shape on one side deviating from the optical axis O-O ′ is a plano-convex lens shape having a convex surface facing the light source 11, and an extended rotation free-form surface is used for the convex surface. In FIG. 3, the curve (a), a curve translated by the distance R in the positive direction of the Z axis, the distance R and the angle θ, the coordinate system before the movement, and the moved coordinate system are represented by the angle θ. A rotated coordinate system is shown (the same applies to FIGS. 4 to 6 below).

And when the extended rotation free-form surface used for the donut-shaped lens 10 has aspherical components C ₂ , C ₃ , C ₄ , C ₅ ... The aspherical surface becomes asymmetric, so-called coma aberration is generally generated, and the light condensing state is deteriorated.

  Now, integrating the donut-shaped lens 10 and the annular opening plate 1 is preferable because it eliminates the need to match the annular condensed image and the annular opening 2.

  In the case of phase difference observation, it is necessary to correctly match the image of the annular aperture 2 with the annular-shaped phase film 7 disposed in the objective lens 5, and furthermore, the annular-shaped collection formed by the donut-shaped lens 10. Correctly aligning the position of the optical image with the annular aperture 2 makes the adjustment of the optical system very complicated. Therefore, it is desirable to integrate the donut-shaped lens 10 and the annular zone opening plate 1.

  More preferably, in order to simplify the adjustment of the optical system, it is preferable to have positioning means so that the annular zone opening plate 1 integrated with the donut-shaped lens 10 can be always set at a normal position.

  Further, in the case of dark field observation (FIG. 2), the annular aperture plate 1 may be finely adjusted in the direction of the optical axis OO ′ depending on the thickness of the slide glass of the sample placed on the specimen surface 4. In addition, it is preferable in terms of operation that the donut-shaped lens 10 and the annular zone opening plate 1 are integrated.

  Further, in order to reduce the spherical aberration (coma aberration) in the sagittal section generated in the donut-shaped lens 10, the shape on one side deviating from the optical axis OO ′ of the meridional section has a convex surface directed toward the light source 11 side. It is preferable to use a plano-convex lens.

  Next, it is preferable that the radius R from the optical axis O-O ′ of the convex surface top of the donut-shaped lens 10 is substantially the same as the radius r of the annular opening 2 (FIG. 3).

  When the diameter of the annular zone opening 2 is larger than the radius D of the light beam incident on the donut-shaped lens 10, as shown in FIG. 4, from the optical axis OO ′ at the top of the convex surface of the donut-shaped lens 10. It is preferable to make the radius R of these larger than D / 2. Further, as shown in FIG. 5, when the diameter of the annular opening 2 is smaller than the light beam radius D, the radius R from the optical axis OO ′ at the top of the convex surface of the donut-shaped lens 10 is set to D. It is preferable to make it smaller than / 2.

  Furthermore, as shown in FIGS. 4 and 5, when the direction of the light beam exiting the annular opening 2 is inclined with respect to the optical axis OO ′, as shown in FIG. It is preferable to arrange a refracting member 14 having a wedge-shaped cross section that gives a declination. Such a configuration is particularly effective when a high-magnification objective lens 5 is used.

Further, when the meridional cross-sectional shape of the convex surface of the donut-shaped lens 10 is configured as an aspherical surface, the aspherical surface is formed so that the curvature becomes gentler (smaller) away from the top of the convex surface (toward the lens outer periphery and the lens center). It is preferable to give the terms C ₃ , C ₅ , C _{7 and the} like.

  Furthermore, by forming the convex surface of the donut-shaped lens 10 with a Fresnel lens surface, the thickness in the direction of the optical axis O-O ′ can be reduced, and it can be arranged in a narrow illumination optical path.

  In addition, a diffusing element 12 is disposed in the condensing optical system 13 and the light beam is converted into a substantially uniform light beam spread to a certain extent, so that the position irregularity of the filament or arc of the light source 11 (directivity depending on the light emission direction of the light beam) is changed. This is effective for removing (not unevenness). In particular, in the case of critical illumination, the light source 11 is directly projected onto the specimen surface 4, and therefore it is effective to dispose the diffusing element 12 to remove this unevenness.

Further, the light emitting portion of the light source 11 is generally generally 1 mm to 1 mm × 3 mm in size. On the other hand, the width of the annular aperture 2 for phase difference observation is usually around 1 mm. Therefore, in order to efficiently project the light emitting part onto the annular aperture 2, the condensing optical system 13 and the donut-shaped lens 10 are provided. When the projection magnification from the light source 11 to the light source image in the included meridional section is β,
0.1 <β <20 (1)
It is preferable to satisfy the following conditions.

  If the lower limit of 0.1 of the conditional expression (1) is exceeded, the size of the light source 11 at the meridional section becomes small, but the light spread (NA) at the meridional section after the light source image formation becomes too large, The wide specimen surface 4 is illuminated unnecessarily, and the illumination efficiency is deteriorated.

  On the other hand, if the upper limit of 20 in the conditional expression (1) is exceeded, the light source image becomes too large and the light flux passing through the annular opening 2 decreases, which also reduces the illumination efficiency.

  Incidentally, since the donut-shaped lens 10 has no power in the sagittal section, the projection magnification in the sagittal section takes different values.

More preferably,
1 <β <10 (1-1)
It is preferable to satisfy the following conditions.

  Next, one specific example of the donut-shaped lens 10 is shown. The configuration parameters of the donut lens 10 will be described later. As shown in FIG. 7, the configuration parameters of this embodiment are based on the result of tracking forward rays in the order in which light from the light source 11 passes through the donut-shaped lens 10.

  The coordinate system uses the position on the optical axis OO ′ of the image plane, which is the surface formed by the condensing point of the donut-shaped lens 10, in the forward ray tracing as the origin of the decentered optical surface, and the optical axis OO ′. The direction in which light travels is the positive Z-axis direction, the upward direction in FIG. 7 orthogonal to the Z-axis is the Y-axis positive direction, and the plane of the paper in FIG. 7 is the YZ plane. The axes constituting the Y-axis and Z-axis and the right-handed orthogonal coordinate system are defined as the X-axis positive direction.

  For the decentered surface, the amount of decentering from the center of the origin of the optical system in the coordinate system in which the surface is defined (X-axis direction, Y-axis direction, and Z-axis direction are X, Y, and Z, respectively) and the optical system The inclination angles (α, β, γ (°), respectively) of the coordinate system defining each surface centered on the X axis, Y axis, and Z axis of the coordinate system defined at the origin are given. In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by rotating the coordinate system defining each surface counterclockwise around the X axis of the coordinate system defined at the origin of the optical system. Then rotate it around the Y axis of the new rotated coordinate system by β and then rotate it around the Z axis of another rotated new coordinate system by γ. It is.

  Further, among the optical action surfaces constituting the optical system of the above embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given, in addition, the curvature radius of the surface, The refractive index and Abbe number of the medium are given according to conventional methods.

  It should be noted that a term relating to an aspheric surface for which no data is described in the configuration parameters described later is zero. About a refractive index and an Abbe number, the thing with respect to d line (wavelength 587.56nm) is described. The unit of length is mm. The decentering of each surface is represented by the amount of decentering from the position on the optical axis O-O ′ of the image surface, which is the surface formed by the condensing point of the donut lens 10 as described above.

  The extended rotation free-form surface is a rotationally symmetric surface given by the following definition.

  First, the following curve (b) passing through the origin on the YZ coordinate plane is determined.

^{Z = (Y 2 / RY)} / [1+ {1- (C 1 +1) Y 2 / RY 2} 1/2]
C ₂ Y + C ₃ Y ² + C ₄ Y ³ + C ₅ Y ⁴ + C ₆ Y ⁵ + C ₇ Y ⁶
+ ··· + C ₂₁ Y ²⁰ + ··· + C _{n + 1} Y ⁿ + ····
... (a)
Next, a curve F (Y) obtained by rotating the curve (b) in the positive direction of the X-axis and turning it counterclockwise to be positive is determined. This curve F (Y) also passes through the origin on the YZ coordinate plane.

  The curve F (Y) is translated in the positive Z direction by a distance R (or negative Z direction if negative), and then the rotationally symmetric surface formed by rotating the translated curve around the Y axis is expanded and rotated. Let it be a free-form surface.

  As a result, the extended rotation free-form surface becomes a free-form surface (free-form curve) in the YZ plane and a circle with a radius | R | in the XZ plane.

  From this definition, the Y-axis becomes the axis of the extended rotation free-form surface (rotation symmetry axis).

Where RY is the radius of curvature of the spherical term in the YZ section, C ₁ is the conic constant, C ₂ , C ₃ , C ₄ , C ₅ . Aspheric coefficient.

  Note that the definition of the extended rotation free-form surface is substantially the same, although slightly different from the expression of the above definition.

  FIG. 7 is a cross-sectional view taken along the optical axis O-O ′ of one specific example of the donut-shaped lens 10, and FIG. 8 is a perspective view thereof. FIG. 7 also shows an optical path.

  This donut-shaped lens 10 includes an extended rotation free-form surface 21 in which the shape on one side deviating from the optical axis OO ′ in the cross section including the optical axis OO ′ is a convex surface toward the light source 11, and the annular aperture plate 1. When the light beam parallel to the optical axis OO ′ is incident on the donut-shaped lens 10 from the light source 11 side, the image plane with the coordinate axis defined is formed. The light is collected in a ring shape on a circle with a radius of 7.5 mm centered on the optical axis OO ′. At that position, the annular opening 2 of the annular opening plate 1 is arranged.

  The effective diameter of the donut-shaped lens 10 of Example 1 is φ30 mm, the focal length of the meridional section is 32.93 mm, and the projection magnification of the light source 11 when an aspherical lens with a focal length of 10 mm is used as the condensing optical system 13. β is 3.29 times.

  The configuration parameters of specific example 1 are shown below. In the table below, “ERFS” indicates an extended rotation free-form surface.

Example 1
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 ERFS [1] Eccentricity (1) 1.5163 64.1
2 ∞ Eccentricity (2)
Image plane ∞
ERFS [1]
RY 17.07
θ -90.00
R 7.5
C ₅ -1.4068 × 10 ^-5
Eccentricity (1)
X 0.00 Y 0.00 Z -35.00
α 90.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y 0.00 Z -30.00
α 0.00 β 0.00 γ 0.00.

  As described above, the illumination optical system and the microscope illumination apparatus according to the present invention have been described based on the embodiments. However, the present invention can be variously modified. For example, it is a matter of course that the shape of one side of the doughnut-shaped lens 10 deviating from the optical axis O-O ′ in the cross section including the optical axis O-O ′ may be a biconvex lens shape.

1 is a layout diagram of a phase difference observation optical system of one example to which an illumination optical system of the present invention is applied. FIG. It is a layout view of a dark field observation optical system of one example to which the optical system for illumination of the present invention is applied. It is sectional drawing of one form of a donut-shaped lens. It is sectional drawing of the form of a donut-shaped lens in case the diameter of annular zone opening is large compared with the incident light beam radius. It is sectional drawing of the form of a donut-shaped lens in case the diameter of an annular zone opening is small compared with the incident light beam radius. It is sectional drawing which shows a countermeasure when the direction with respect to the optical axis of the light beam which inject | emits an annular aperture will incline. It is sectional drawing taken along the optical axis of one specific example of a donut-shaped lens. It is a perspective view of the specific example of FIG. It is the figure which showed the optical path at the time of phase difference observation of the conventional phase difference observation optical system after annulus opening. It is the figure which showed the optical path at the time of dark field observation of the conventional dark field observation optical system after annulus opening.

Explanation of symbols

OO '... Optical axis 1 ... Ring zone aperture plate 2 ... Zone zone aperture 3 ... Condenser lens 4 ... Sample surface 5 ... Objective lens 6 ... Exit pupil 7 of objective lens ... Phase film 8 ... Image plane 9 ... Diaphragm 10 ... Donut-shaped lens 11 ... Light source 12 ... Diffusing element 13 ... Condensing optical system 14 ... Refraction member 21 having a wedge-shaped cross section ... Surface on the light source side of the donut-shaped lens (extended rotation free-form surface)
22 ... The surface (plane) of the donut-shaped lens on the annular zone opening side

Claims (10)

A light source, a condensing optical system that condenses and diverges or collimates the light flux emitted from the light source, a donut-shaped lens that collects the light flux in an annular shape, and condenses the annular light An annular aperture disposed in the vicinity of the condensing position of the luminous flux, and a condenser lens that projects an image of the annular aperture on the pupil position of the objective lens of the observation optical system or the projection optical system, Lighting optical system. The illumination optical system according to claim 1, wherein the donut-shaped lens and the annular zone opening are integrated. The donut-shaped lens has a shape that is rotationally symmetric around the optical axis, and the shape on one side deviating from the optical axis of the cross section including the optical axis is a plano-convex lens shape with the convex surface facing the light source side. The illumination optical system according to claim 1, wherein the illumination optical system is an illumination optical system. 4. The illumination optical system according to claim 3, wherein R≈r, where R is a radius from the optical axis at the top of the convex surface, and r is a radius of the annular opening. The illumination optical system according to claim 3 or 4, wherein the convex surface is a surface whose curvature becomes gentler toward the periphery. The illumination optical system according to claim 1, wherein the donut-shaped lens is a Fresnel lens. The illumination optical system according to any one of claims 1 to 6, wherein the condensing optical system includes a diffusing element that makes a condensed light flux uniform. When the projection magnification from the light source to the light source image in the cross section including the optical axis including the condensing optical system and the donut-shaped lens is β,
0.1 <β <20 (1)
The illumination optical system according to claim 1, wherein the following condition is satisfied. 9. The illumination optical system according to claim 1, wherein the illumination optical system is used in an illumination device of a microscope having a phase difference observation optical system, and a phase film is formed at a projection position of the annular opening of the phase difference observation optical system. Is arranged in a ring shape. The illumination optical system according to any one of claims 1 to 8 is used in an illumination apparatus of a microscope including a dark field observation optical system, and has a numerical aperture larger than a numerical aperture of an objective lens of the dark field observation optical system. A microscope illumination apparatus characterized in that dark field illumination is performed by condensing a light beam on a sample surface of the dark field observation optical system via the condenser lens.

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