JP2012123326A - Coaxial epi-illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial epi-illumination device which does not impose restriction on design of an objective lens, reduces lowering of light volume at a center part even in a microscope of low magnification, and can decrease flare spots.SOLUTION: A coaxial epi-illumination device 1 is incorporated in a microscope body having an objective lens 400 which can irradiate an observation object to be imaged, with illumination light in a microscope system. The coaxial epi-illumination device 1 comprises: a light source 100 for generating irradiation light; and an illumination optical system 300 including an illumination lens which forms an image of the light source 100 on an incident surface side 410 of the objective lens 400. Moreover, the coaxial epi-illumination device 1 further comprises blocking means 600 for preventing light emission of a center part of a circular light-emitting surface 210 which emits the illumination light from the light source 100 toward the illumination optical system 300.

Description

  The present invention relates to an illumination device that irradiates an observation object with artificial light for a microscope system or the like, and more particularly to a coaxial epi-illumination device having a function of reducing a flare spot in which a central portion of an observation image is brightened by reflected light.

  A microscope system or the like includes an observation optical system and is used for highly accurate positioning and substrate inspection in a manufacturing process. Such a microscope system includes an illumination device that irradiates an observation object with artificial light in addition to a microscope main body having an objective lens, a lens barrel, and an eyepiece, and an imaging device that captures imaging data of the observation object. An output camera or the like is connected. The imaging data of the observation object is subjected to image processing and various arithmetic processing by an arithmetic element or the like in the control unit as necessary, and is used for the positioning processing and the substrate inspection described above.

  In the conventional microscope system, for example, an observation object is illuminated by illumination from an oblique direction using a ring light guide or the like, and an observation image having a sufficient amount of light with respect to the sensitivity of the camera is obtained. However, in the case of an observation target such as a resin or semiconductor wafer having a smooth metal mirror surface or surface, the reflected light does not sufficiently enter the lens when illuminated obliquely, and the amount of light may be insufficient. In addition, there is a problem in that regular reflection light necessary for observing the surface gloss or the difference in structure of the observation object cannot be output. In order to deal with such a problem, by using a half mirror, the direction of the illumination light incident from the side of the microscope system is changed to be perpendicular to the observation object, and the lens Coaxial epi-illumination is known in which the optical axis and the optical axis of the illumination are matched. In such a coaxial epi-illumination device, the objective lens also functions as a condenser that collects the illumination light.

  A coaxial epi-illumination device used in a microscope system is, for example, a segmented prism (half mirror) in a lens barrel portion between an objective lens and an eyepiece lens (or an imaging surface of an imaging device) on the observation object side of the microscope body. Then, the illumination light is connected from the side surface toward the observation target so as to be supplied coaxially with the center of the optical path in the lens barrel. Illumination light is supplied from a light source via an illumination optical fiber, for example. In addition to the focusing function for the observation object, the microscope main body has a function for changing the magnification, for example, the lens position is slid in the optical path to wide and wide (tele) Some have a zoom function that changes to any magnification between the sides. Some coaxial incident illumination optical systems are provided with a stop, and there are some that can limit the illumination light irradiation range and the irradiation angle by opening and closing the stop. In addition, there are some that shield the end of the illuminating light beam and enable observation close to oblique irradiation.

  By the way, in the coaxial epi-illumination device, the objective lens is used as a condenser and the illumination light is irradiated through the objective lens, and the light beam reflected by the surface of the objective lens is superimposed on the observation image. Brightness unevenness occurs due to a large light amount difference between the center and the periphery of the image. As a result, the coaxial epi-illumination device has a problem that a flare spot (hot spot) is generated that lowers the contrast of the image at the center and reduces the observation accuracy.

  In the flare spot, most of the illumination light incident along the optical axis is transmitted through the objective lens, while a part of the illumination light is reflected on the incident side surface (back surface) of the objective lens and the reflected illumination light Some of them occur along the optical axis after reflection and reach the imaging surface of the imaging element of the camera used for observation. In addition, the reflected light includes light that is reflected from a part of the light incident on the surface of the image pickup device and re-reflected on the surface of the split prism and returns to the surface of the image pickup device. In particular, when the reflected light is collected at the center of the camera, a flare spot having a large difference between the amount of light at the center of the observed image and the amount of light at the peripheral portion is generated. Such flare spots are more likely to occur due to the recent increase in pixels and sensitivity of imaging devices.

  When a flare spot having a large light amount difference between the center and the peripheral portion occurs, a light amount difference exceeding the light amount range that can be detected by the camera (difference between the darkest portion and the re-bright portion) may occur. In that case, even if the amount of illumination light is adjusted, overexposure of the center part or blackening of the peripheral part occurs, and a high-quality image cannot be obtained.

  In order to reduce this flare spot, conventionally, a neutral density filter including a one-sided filter is installed in front of the image sensor, or a λ / 4 wavelength plate or a polarizing plate is disposed between the objective lens and the image sensor. In addition, it has been proposed that they be arranged at an angle from the optical axis, or that a highly accurate antireflection film be used. However, flare spots cannot be removed when the intensity of illumination light is high or when the illumination light has an infrared wavelength, resulting in an increase in the number of parts, high costs, or placement in front of the image sensor. If the surface accuracy of the filter or the like is poor, the resolving power is lowered, and there is a problem that the accuracy in positioning is lowered.

  For the above problem, without placing a filter or the like in front of the image sensor, the curvature radius of the back surface (reflecting surface) of each lens and the combined focal length of the lens disposed behind the reflecting surface are conditioned. In other words, a method of reducing the flare spot by limiting the design of the objective lens and carefully designing the reflected light so that it does not collect at the center has been proposed (see, for example, cited document 1). In addition, a method has been proposed in which a light-shielding unit that shields the central light beam is disposed in the vicinity of the pupil position of the objective lens (condenser) (see, for example, cited document 2). Furthermore, a one-shot adapter (one-shot filter) that shields light by covering half of the light emitting surface of the illumination is known. By attaching the one-shot adapter to the light emitting surface of the illumination, a detailed surface shape that is difficult to detect even under the coaxial incident illumination can be raised.

JP 2009-251081 A JP 2006-330359 A

  However, as the specification requirement for the objective lens in recent years increases, the method of the cited document 1 deals with the objective lens side, so that the restriction of the design of the objective lens cannot be eliminated, and the microscope system using the existing objective lens. Therefore, there is an increasing demand for eliminating restrictions on lens design.

  Further, the method of the cited document 2 cannot improve the flare spot without problems in every case. In the method of shielding the vicinity of the pupil position of the objective lens of the cited document 2, the illumination light from the light source is reduced when entering the objective lens, and the reflected light from the observation object passes through the objective lens and the observation optical system. Is also reduced when the illumination light reciprocates. Therefore, in the case where the shielding hardly affects the amount of light at the time of observation, for example, in the case of a microscope having a large NA and a large amount of light flux emitted from the objective lens, the flare spot can be improved without causing a decrease in the amount of light. . However, for example, when the microscope has a zoom function, and the NA is small and the emitted light beam from the objective lens is small as in the zoom function when the zoom lens is set to the low magnification side (wide side), the method of Reference 2 is used. If the vicinity of the pupil position of the objective lens is shielded, there is a problem that the amount of light at the center of the observation image is lowered to a level inappropriate for observation. In addition, since the amount of light is also halved in the one-shot adapter, there is a problem that when a large amount of light is required, the level is reduced to an inappropriate level for observation.

  Therefore, in order to solve the above-mentioned problems, the present invention does not place restrictions on the design of the objective lens, and even with a low magnification microscope, there is little decrease in the amount of light at the center of the observed image, and flare spots can be reduced. An object of the present invention is to provide a coaxial epi-illumination device.

(1) In order to solve the above-described problem, a coaxial epi-illumination device according to an embodiment of the present invention is incorporated in a microscope main body including an objective lens having a condenser function capable of irradiating illumination light onto an observation object to be imaged. A coaxial epi-illumination device, having a light source that generates irradiation light, and an illumination optical system that includes an illumination lens that forms an image of the light source on the incident surface side of the objective lens, and further illuminates the illumination light from the light source A blocking means for preventing light emission at the center of the circular light emitting surface that emits toward the system is provided.
According to this embodiment, by providing the shielding means, it is possible to reduce the decrease in the amount of light at the center of the observation image even at a low magnification while reducing the flare spot without restricting the design of the objective lens.

(2) Preferably, the coaxial epi-illumination device according to an embodiment of the present invention includes a light guide unit that guides the irradiation light to the light emitting surface, and the illumination optical system uses a microscope to emit the irradiation light emitted from the light emitting surface. You may make it guide | lead so that it may become coaxial with an inner optical path.
According to this embodiment, the light guide unit and the illumination optical system can guide the irradiation light from the light source to the illumination optical system with less attenuation and diffusion.

(3) Preferably, in the coaxial epi-illumination device according to one embodiment of the present invention, the shielding means is an opaque disk that prevents light emission at the center of the light emitting surface into a circle having a diameter smaller than the diameter of the light emitting surface. There may be.
According to this embodiment, since light emission at the center of the light emitting surface is prevented to be a circle having a diameter smaller than the diameter of the light emitting surface, the flare spot can be reduced while reducing the amount of light at the center of the observation image. it can.

(4) Preferably, in the coaxial epi-illumination device according to one embodiment of the present invention, the shielding means has a size larger than the diameter of a disk that looks into the entrance pupil of the illumination lens from the position of the light source on the optical axis of the illumination optical system. It may be circular.
According to this embodiment, since the shielding means is larger than the disk that looks into the entrance pupil of the illumination lens, flare spots can be effectively reduced.

(5) Preferably, in the coaxial epi-illumination device according to an embodiment of the present invention, the shielding means is disposed at the center of the front surface of the light emitting surface on the illumination optical system side and has a predetermined diameter smaller than the diameter of the light emitting surface. An opaque circular shielding plate having the following area may be used.
According to this embodiment, since a part of the light beam is blocked by a circular light-emitting surface with an opaque circular light-shielding plate having a diameter smaller than that of the light-emitting surface, all directions except for the central portion of the circular light-emitting surface are used. Light can be evenly emitted from the surrounding portion, and flare spots can be reduced while reducing a decrease in the amount of light at the center of the observation image.

(6) Preferably, in the coaxial epi-illumination device according to one embodiment of the present invention, a circular shielding means having a predetermined diameter smaller than the diameter of the light emitting surface is disposed a predetermined distance from the light emitting surface to the illumination optical system side. May be.
According to this embodiment, since the circular light shielding plate having a predetermined diameter smaller than the diameter of the light emitting surface is arranged in front of the light emitting surface by a predetermined distance to block a part of the light beam, the central portion of the observation image is obtained even at a low magnification. The flare spot can be reduced while reducing the decrease in the amount of light.

(7) Preferably, in the coaxial epi-illumination device according to an embodiment of the present invention, the light emitting surface is a circle having a diameter of 3.8 mm, and the shielding means is a circle having a diameter of 1.0 mm, from the light emitting surface. You may arrange | position 0.7 mm ahead.
According to the present embodiment, the shielding means is made circular with a diameter of 1.0 mm with respect to a circular light emitting surface with a diameter of 3.8 mm, thereby reducing a decrease in the amount of light at the center of the observation image even at a low magnification. , Flare spots can be reduced.

(8) Preferably, in the coaxial epi-illumination device according to an embodiment of the present invention, the shielding means may be a circular opaque portion provided at the center of the light emitting surface.
According to this embodiment, an opaque portion having a circular cross section is provided at the center of the circular light emitting surface, and light rays are blocked by the opaque opaque portion having a smaller diameter than the light emitting surface. Light can be evenly emitted from the peripheral portions in all directions except for the central portion of the light emitting surface, and flare spots can be reduced while reducing the amount of light at the central portion of the observation image.

(9) Preferably, in the coaxial epi-illumination device according to an embodiment of the present invention, the shielding means is a circular cross-section cavity provided at the center of the light guide, and the light guide has a donut-shaped cross section. There may be.
According to this embodiment, since the circular cross-section hollow portion is provided at the center of the circular cross-section light guide section so that the cross-section of the light guide section has a donut shape, However, since the light beam is reflected at the boundary surface with the small-diameter cavity and the light entering the cavity is small, light can be evenly emitted from the peripheral parts in all directions except for the central part of the circular light-emitting surface. The flare spot can be reduced while reducing the decrease in the amount of light at the center of the observed image.

(10) Preferably, in the coaxial epi-illumination device according to an embodiment of the present invention, the optical system is a telecentric optical system that converts the irradiation light emitted from the light emitting surface into parallel light on the emission side (observation surface side) of the objective lens. It may be a system.
According to this embodiment, since the illumination optical system is a telecentric system, it is possible to reduce an increase or decrease in the optical intensity of the flare spot due to an increase or decrease in the distance to the imaging position.

  According to the coaxial epi-illumination device of the present invention, there is no restriction on the design of the objective lens, and it can be applied to an existing objective lens. Spots can be reduced, and high-quality images can be observed.

(A)-(c) is a figure which shows schematic structure until the light radiate | emitted from the light emission surface in the optical path of the conventional coaxial epi-illumination device injects into a microscope. (A), (b) is a figure which shows schematic structure which the light radiate | emitted from the conventional coaxial epi-illumination device reflects with the objective lens of a microscope, and generates a flare spot. (A)-(c) is a figure which shows the flare spot which the light radiate | emitted from the conventional coaxial epi-illumination device reflected and generate | occur | produced with the objective lens of the microscope. (A)-(j) are the spot diagrams of the light ray which radiate | emits from each part of a light emission surface, and reaches an observation surface in the conventional coaxial epi-illumination apparatus. It is a graph which shows the encircled energy of each spot of (a)-(i) of FIG. It is the photograph which image | photographed the flare spot which the magnification of the conventional coaxial epi-illumination device microscope concentrated on the wide side. (A)-(c) is a figure which shows schematic structure until the light radiate | emitted from the light emission surface which provided the one shot adapter to the optical path of a coaxial epi-illumination device injects into a microscope. (A)-(j) are the spot diagrams of the light ray which radiate | emits from each part of the light emission surface, and reaches | attains an observation surface in the coaxial epi-illumination apparatus which provided the single shot adapter to the light emission surface. It is a graph which shows the encircled energy of each spot of (a)-(i) of FIG. (A) to (j) are spot diagrams of light beams that are emitted from each part of the light emitting surface and reach the observation surface in a coaxial epi-illumination device in which a light shielding means for shielding the central light beam is disposed in the vicinity of the pupil position of the objective lens. It is. It is a graph which shows the encircled energy of each spot of (a)-(i) of FIG. (A)-(d) is a figure which shows schematic structure until the light radiate | emitted from the light emission surface in the optical path of the coaxial incident illumination apparatus of one Embodiment of this invention enters into a microscope. (A), (b) is a figure which shows schematic structure by which the light radiate | emitted from the coaxial epi-illumination device of this invention reflects with the objective lens of a microscope, and does not generate | occur | produce a flare spot. (A)-(j) is the spot diagram of the light ray which radiate | emits from each part of the light emission surface of the axial epi-illumination device of this invention, and reaches an observation surface. It is a graph which shows the encircled energy of each spot of (a)-(i) of FIG. It is the photograph which image | photographed the flare spot which concentrated when the magnification of a microscope was made into the widest side with the axial epi-illumination apparatus of this invention. (A)-(d) is a figure which shows the main structures of the coaxial epi-illumination device of other embodiment of this invention.

The first embodiment of the present invention will be described below in detail with reference to the drawings.
<Supplementary explanation of the prior art>
1A is a schematic diagram from the light source to the objective lens of the microscope, FIG. 1B is an optical path diagram from the light emitting surface of the optical fiber to the observation object, and FIG. 1C is a diagram of the illumination optical system from the light emitting surface. It is an enlarged view. FIG. 2A is a diagram showing an observation optical system and an optical path when a concentrated flare spot is generated when the magnification of the microscope is set to the lowest side, and FIG. 2B is an enlarged view of the microscope. It is a figure which shows the observation optical system and optical path in the case of generating the diffused flare spot at the time of setting magnification to the telephoto side most. Further, FIG. 3 (a) is a diagram showing concentrated flare spots when the wide side corresponding to FIG. 2 (a) is used, and FIG. 3 (c) is the tele side corresponding to FIG. 2 (c). It is a figure which shows the flare spot which spread | diffused in the case, (b) is a figure which shows the flare spot 2000 of the intermediate magnification.

  The coaxial epi-illumination device 1 shown in FIG. 1 and FIG. 2 is a device that enables illumination light to be irradiated coaxially to the observation object 800 to be imaged shown in the upper side of FIG. By inserting a splitting prism having a half mirror 700 between the microscope objective lens 400 and the observation optical system 900, illumination light enters from the direction perpendicular to the optical axis of the microscope and is coaxial with the optical axis of the microscope. The observation object 800 is illuminated. Illumination light emitted from the light source 100 is guided to the circular light emitting surface 210 by the optical fiber 200 that is a light guide section having a circular cross section, and the illumination light is emitted from the light emitting surface 210 toward the illumination optical system 300. The illumination light is emitted from both the central part and the peripheral part of the light emitting surface 210 as shown in FIG. The optical fiber 200 can guide the irradiation light from the light source 100 to the illumination optical system 300 with little attenuation and diffusion, and may be a single fiber or a bundle of a plurality of fibers.

  The illumination optical system 300 guides the illumination light emitted from the light emitting surface 210 to the objective lens 400 in the microscope so as to be coaxial with the optical path in the microscope. The illumination optical system 300 is a telecentric optical system that emits irradiation light emitted from the light emitting surface 210 as parallel light from the exit surface side (observation surface side) of the objective lens 400. By making the illumination optical system 300 a telecentric system, the increase and decrease of the optical intensity of the flare spot 2000 due to the increase and decrease of the distance to the imaging position is reduced. Furthermore, the illumination optical system 300 forms an image of the light source 100 on the incident surface side 410 of the objective lens 400 by an internal illumination lens.

  The objective lens 400 has a condenser function for condensing illumination light on the observation object 800, and causes reflected light from the observation object 800 to enter the observation optical system 900. The observation optical system 900 includes a magnification changing optical system 910 that can change the magnification from a wide angle (wide) side to a narrow angle (tele) side, and an image of the observation object 800 on an image sensor 1000 of a camera (not shown). Can be imaged.

  On the other hand, as described above, part of the illumination light emitted from the illumination optical system 300 is reflected by the surface of the objective lens 400. The reflected illumination light enters the observation optical system 900 together with the reflected light from the observation object 800. The reflected light from the objective lens 400 is superimposed on the observation image of the observation object 800 on the image sensor 1000 to increase the luminance of the superimposed portion. When the magnification of the microscope is set to the wide side as shown in FIG. 2 (a), the reflected light from the objective lens 400 is collected by the observation optical system 900 and imaged as shown in FIG. 3 (a). A flare spot 2000 is generated on the element 1000. In the case of FIG. 3A, there is a large light amount difference between the center and the peripheral part of the observation image on the imaging surface of the image sensor 1000, and large brightness (luminance) unevenness occurs. As a result, the coaxial epi-illumination apparatus 1 generates a flare spot (hot spot) 2000 that lowers the contrast of the image at the center of the microscope observation image and reduces the observation accuracy. On the other hand, when the magnification of the microscope is set to the tele side as shown in FIG. 2B, the reflected light from the objective lens 400 is diffused by the observation optical system 900, and as shown in FIG. The rate at which the flare spot 2000 is generated decreases. FIG. 3B shows a flare spot 2000 having an enlargement ratio between the above two.

  4A is a spot diagram at the center of the light emitting surface, FIG. 4B is a spot diagram at 0.5 mm above the center of the light emitting surface, and FIG. 4C is a spot at 1.0 mm above the center of the light emitting surface. 4 (d) is a spot diagram 1.5mm above the center of the light emitting surface, FIG. 4 (e) is a spot diagram 1.9mm above the center of the light emitting surface, and FIG. 4 (f) is the center of the light emitting surface. 4 (g) is a spot diagram 1.0 mm below the center of the light emitting surface, FIG. 4 (h) is a spot diagram 1.5mm below the center of the light emitting surface, FIG. i) is a spot diagram 1.9 mm below the center of the light emitting surface, and FIG. 4 (j) is a diagram in which (a) to (i) are superimposed. FIG. 5 shows the encircled energy of each of the spots (a) to (i) in FIG. 4, and 1.5 mm vertically from the center of the light emitting surface (x = 0.0, y = 0.0). The light beam emitted from the light-emitting surface reaches the inside of a circle with a radius of 5000 μm from the center of the observation surface. It indicates that the light beam does not reach the observation surface at 1.9 mm or more above and below the center of the light emitting surface. FIG. 6 is a photograph taken of a concentrated flare spot 2000 when the enlargement magnification of FIG. As described above, when the enlargement magnification is set to the wide side, the observation image on the imaging surface of the imaging device 1000 cannot be clearly observed due to the influence of the flare spot 2000.

<Supplementary Description of Conventional Technology: Conventional Reference Example 1 (One-shot Adapter)>
7A is a schematic diagram from the light source to the objective lens of the microscope, FIG. 7B is an optical path diagram from the light emitting surface of the optical fiber to the observation object, and FIG. 7C is a diagram of the illumination optical system from the light emitting surface. It is an enlarged view. 8A is a spot diagram at the center of the light emitting surface, FIG. 8B is a spot diagram 0.5 mm above the center of the light emitting surface, and FIG. 8C is 1.0 mm above the center of the light emitting surface. 8 (d) is a spot diagram 1.5 mm above the center of the light emitting surface, FIG. 8 (e) is a spot diagram 1.9mm above the center of the light emitting surface, and FIG. 8 (f) is a light emitting surface. FIG. 8 (g) is a spot diagram 1.0mm below the center of the light emitting surface, FIG. 8 (h) is a spot diagram 1.5mm below the center of the light emitting surface, FIG. 8 (i) is a spot diagram 1.9 mm below the center of the light emitting surface, and FIG. 8 (j) is a diagram in which (a) to (i) are superimposed. FIG. 9 shows that a light beam emitted from the lower half of the light emitting surface from a point of 1.9 mm or more and the center of the light emitting surface does not reach the observation surface.

  In Reference Example 1, in order to make a detailed surface shape that is difficult to detect even under coaxial epi-illumination stand out, a one-way adapter (one-shot filter) that covers the light-emitting surface 210 of the illumination and covers half of the light-emitting surface 210 of the illumination. 500 is attached. By providing the one-shot adapter 500 between the light emitting surface 210 and the illumination optical system 300, theoretically, only irradiation light having an area half the light emitting surface reaches the image sensor 1000. However, as can be seen from the comparison between FIG. 8 and FIG. 4, in fact, in addition to the fact that (a) to (d) of the half of the light emitting surface are completely eliminated, the amount of light in (f) is also partially reduced. The effective illumination light is less than half. Therefore, in Reference Example 1 using the one-shot adapter, the amount of light is reduced as a whole and the amount of light at the center is also reduced. Therefore, there is a possibility that the influence of the flare spot 2000 can be reduced. There is a possibility that it will not be possible to observe a good quality image because the amount of light and the amount of light at the center are insufficient, or the amount of light necessary to capture an observation image on one side with the light amount cut is insufficient. When many are required, there is a problem that the level drops to an inappropriate level for observation.

<Supplementary Description of Conventional Technology: Conventional Reference Example 2 (Patent Document 2)>
10A is a spot diagram at the center of the light emitting surface, FIG. 10B is a spot diagram at 0.5 mm above the center of the light emitting surface, and FIG. 10C is a spot at 1.0 mm above the center of the light emitting surface. 10D is a spot diagram 1.5 mm above the center of the light emitting surface, FIG. 10E is a spot diagram 1.9 mm above the center of the light emitting surface, and FIG. 10F is the center of the light emitting surface. 10 (g) is a spot diagram 1.0 mm below the center of the light emitting surface, FIG. 10 (h) is a spot diagram 1.5mm below the center of the light emitting surface, FIG. i) is a spot diagram 1.9 mm below the center of the light emitting surface, and FIG. 10 (j) is a diagram in which (a) to (i) are superimposed. In addition, FIG. 11 shows that light rays emitted from a point of 1.9 mm or more up and down and the center of the light emitting surface do not reach the observation surface, but light rays emitted from other points are circles having a radius of 5000 μm from the center of the observation surface. It is shown that the illumination necessary for observation is performed in the same manner as in the above-described prior art.

  In this case, light shielding means for shielding the central light beam is disposed in the vicinity of the pupil position of the objective lens 400. Therefore, when the illumination light emitted from the light source 100 enters the objective lens 400 via the optical fiber 200 and the illumination optical system 300, not only the central light beam is shielded by the light shielding means but also the observation object 800 once. In this case, before the reflected light from the light passes through the objective lens 400 again and enters the observation optical system 900, the central light beam is shielded by the light shielding means. The light is shielded twice during the reciprocation. For example, in the case of a microscope having a large NA and a large light flux emitted from the objective lens 400, shielding the vicinity of the pupil position of the objective lens 400 has little effect on the amount of light during observation. Therefore, in that case, the flare spot 2000 can be improved without causing a decrease in the amount of light.

  However, when the vicinity of the pupil position of the objective lens 400 is shielded by the method of the cited document 2, for example, when the objective lens 400 having a small NA is set to the low magnification side (wide side) with the zoom function of the microscope, the objective lens 400 There is a problem that the amount of emitted light is small, and the amount of light at the center of the observation image is lowered to a level inappropriate for observation.

<First Embodiment>
12A is a schematic diagram from the light source to the objective lens of the microscope, FIG. 12B is an optical path diagram from the light emitting surface of the optical fiber to the observation object, and FIG. 12C is a diagram of the illumination optical system from the light emitting surface. It is an enlarged view and (d) is the figure which looked at the light emission surface and shielding object of (c) from the microscope side. FIG. 13A is a diagram showing an optical system and an optical path when a concentrated flare spot is not generated when the magnification of the microscope is set to the lowest side, and FIG. 13B is a magnification of the microscope. It is a figure which shows the optical system and optical path in the case of not generating the diffused flare spot at the time of making it the tele side most. 14A is a spot diagram at the center of the light emitting surface, FIG. 14B is a spot diagram 0.5 mm above the center of the light emitting surface, and FIG. 14C is 1.0 mm above the center of the light emitting surface. 14 (d) is a spot diagram 1.5 mm above the center of the light emitting surface, FIG. 14 (e) is a spot diagram 1.9mm above the center of the light emitting surface, and FIG. 14 (f) is the light emitting surface. FIG. 14 (g) is a spot diagram 1.0mm below the center of the light emitting surface, FIG. 14 (h) is a spot diagram 1.5mm below the center of the light emitting surface, FIG. 14 (i) is a spot diagram 1.9 mm below the center of the light emitting surface, and FIG. 14 (j) is a diagram in which (a) to (i) are superimposed. Further, FIG. 15 shows that light rays emitted from a point of 1.9 mm or more above and below the center of the light emitting surface and the center of the light emitting surface do not reach the observation surface, but light rays emitted from other points are the center of the observation surface. It reaches the inside of a circle with a radius of 5000 μm and shows that the illumination necessary for the observation is performed in the same manner as in the prior art. FIG. 16 is a photograph of an observation image taken with the conventional configuration shown in FIG. 6 and taken again using the configuration of the first embodiment of the present invention. In the photograph of FIG. 16, the influence of the flare spot 2000, which appeared very strongly in the conventional photograph of FIG. 6, is very small, and the image of the observation object 800 formed on the image sensor 1000 becomes clear. Can be confirmed.

  In the first embodiment of the present invention, in addition to the conventional configuration described above, a blocking means for preventing light emission at the center of the circular light emitting surface 210 that emits illumination light from the light source 100 toward the illumination optical system 300 is provided. Yes. The shielding means is a circular shielding plate 600 that is an opaque disc that is disposed in the center of the front surface of the light emitting surface 210 on the side of the illumination optical system 300 and has a predetermined diameter smaller than the diameter of the light emitting surface 210. Light emission at the center of the surface 210 can be prevented in a circular shape having a diameter smaller than the diameter of the light emitting surface 210. The circular shape having a diameter smaller than the diameter of the light emitting surface 210 is larger than, for example, the diameter of a disk that looks into the entrance pupil of the illumination lens in the illumination optical system 300 from the position of the light emitting surface 210 on the optical axis of the illumination optical system 300. The dimensions are circular.

  In the present embodiment, the circular shielding plate 600 having a predetermined diameter smaller than the diameter of the light emitting surface 210 is disposed in front of the light emitting surface 210 toward the illumination optical system 300 by a predetermined distance. Specifically, for example, when the light emitting surface 210 has a circular shape with a diameter of 3.8 mm, the shielding unit 600 has a circular shape with a diameter of 1.0 mm, and is disposed 0.7 mm before the light emitting surface 210.

  As described above, in the present embodiment, the circular shielding plate 600 having a diameter of 1 mm is placed 0.7 mm ahead of the circular light emitting surface 210 that emits the irradiation light from the light source 100, and the center of the light emitting surface 210 (with respect to the optical axis). By blocking the light emitted from the intersection point), the illumination light incident along the optical axis at the entrance of the objective lens 400 disappears. On the other hand, by placing the shield, the attenuation of the total illumination light amount incident on the objective lens 400 is 20% or less, and the flare spot 2000 can be effectively removed without impairing the use efficiency of the illumination light. it can. Note that the arrangement of the shielding plate 600 is not limited to 0.7 mm forward from the light emitting surface 210 but may be 1 mm forward, for example, and similar results can be obtained.

  According to the present embodiment described above, an opaque circular shape that is larger than the circular light-emitting surface, which is larger than the disk that looks at the entrance pupil of the illumination lens with a diameter smaller than the diameter of the light-emitting surface 210 before the light-emitting surface 210. A shielding plate 600 is provided. Thus, in this embodiment, a part of the light emission at the central portion of the light emitting surface 210 is cut off in a circular shape to prevent emission, but except for the central portion of the circular light emitting surface 210, the light emitting surface 210 is omnidirectional. Light can be evenly emitted from the surrounding portion. Unlike the case of the reference example 2, the light emission is interrupted only once at the time of emission from the light emitting surface 210. Thereafter, the amount of light is not reduced, but only the amount of light at the center can be surely reduced. Therefore, in the present embodiment, the flare spot 2000 can be effectively reduced while reducing the light amount reduction in the central portion of the observation image even at a low magnification without restricting the design of the objective lens 400.

<Application example of the first embodiment>
FIG. 17A is a diagram in the case where a circular opaque portion is provided at the center of the circular light emitting surface, and FIGS. 17B to 17D are provided with a hollow portion having a circular cross section at the center of the light guide portion. FIG. 17D is a bundle fiber in which a plurality of fibers are bundled by the light guide unit in FIG. 17C, and each fiber is biased outward on the light output side, thereby centering the bundle fiber. It is a figure at the time of providing a cavity part.

  In the coaxial epi-illumination device 1 of the application example 1, the shielding means is a circular opaque portion 215 provided in the center of the light emitting surface 210, and in particular, the light emitting surface 210 is not a separate circular shielding plate 600 but a light emitting device. For example, it is attached to the center of the surface 210. Alternatively, an opaque light guide may be provided at the center of the light guide 200. According to the first application example, the opaque portion 215 having a circular cross section is provided at the center of the circular light emitting surface 210, and light is transmitted to the light emitting surface 210 by the opaque opaque portion 215 having a smaller diameter than the light emitting surface 210. Blocked. Therefore, light can be evenly emitted from the peripheral portions in all directions except the central portion of the circular light emitting surface 210, and the flare spot can be reduced while reducing the amount of light at the central portion of the observation image, as in the above-described embodiment. 2000 can be reduced.

  In the coaxial epi-illumination device 1 of the application example 2, the shielding means is a hollow section 250 having a circular cross section provided at the center of the light guide section 200, and the cross section of the light guide section 200 has a donut shape. According to the second application example, the hollow section 250 having a circular cross section is provided at the center of the light guide section 200 having a circular cross section so that the cross section of the light guide section 200 has a donut shape. In this case, the light beam is totally reflected at the boundary surface between the light emitting surface 210 and the cavity portion 250 having a smaller diameter than that of the light emitting surface 210, so that the amount of light entering the cavity portion 250 is reduced. In addition, when the light guide unit 200 is a bundle fiber in which a plurality of fibers are bundled as shown in FIG. 17D, the light incident side is bundled as it is, but on the light output side, each fiber is biased outward. Thus, a hollow portion 250 having a circular cross section can be provided at the center on the light output side by forming a bundle at the center of the bundle fiber. Accordingly, light can be evenly emitted from the peripheral portions in all directions except the central portion of the circular light emitting surface 210, and the flare is reduced while reducing the amount of light at the central portion of the observation image as in the above-described embodiment. Spot 2000 can be reduced.

  In the present embodiment, a case where a shielding plate is provided in front of the center portion of the light emitting surface is shown, and in the application example, an example in which an opaque portion is provided in the center portion of the light emitting surface and an example in which an opaque portion is provided in the center of the light guide portion are shown. However, the present invention is not limited to this, and any method can be used as long as it can block the light at the center in the optical path between the light emitting unit and the illumination optical system. It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

1 coaxial epi-illumination device,
100 light sources,
200 optical fiber,
210 light emitting surface,
215 opaque part,
250 cavity,
300 Illumination optics,
400 objective lens,
410 incident surface side,
500 One shot adapter (one shot filter),
600 shielding plate,
700 half mirror,
800 observation object,
900 observation optical system,
910 magnification changing optical system,
1000 image sensor,
2000 Flare spot (hot spot).

Claims (10)

A coaxial epi-illumination device incorporated in a microscope body provided with an objective lens capable of irradiating illumination light onto an observation object imaged by a microscope system,
A light source that generates illumination light;
An illumination optical system including an illumination lens that forms an image of the light source on the incident surface side of the objective lens;
The coaxial epi-illumination device further comprises a blocking means for preventing light emission from a central portion of a circular light emitting surface that emits illumination light from the light source toward the illumination optical system. A light guide part for guiding the irradiation light to the light emitting surface;
The coaxial incident illumination device according to claim 1, wherein the illumination optical system guides the irradiation light emitted from the light emitting surface so as to be coaxial with an optical path in the microscope. 3. The coaxial epi-illumination according to claim 1, wherein the shielding unit is an opaque disc that prevents light emission at a central portion of the light emitting surface into a circular shape having a diameter smaller than the diameter of the light emitting surface. apparatus. 4. The method according to claim 1, wherein the shielding unit is a circle having a size larger than a diameter of a disk that looks into the entrance pupil of the illumination lens from the position of the light emitting surface on the optical axis of the illumination optical system. The coaxial epi-illumination device according to claim 1. The shielding means is an opaque circular shielding plate having a region with a predetermined diameter smaller than the diameter of the light emitting surface, which is disposed at the center of the front surface of the light emitting surface on the illumination optical system side. Item 5. The coaxial incident illumination device according to any one of Items 1 to 4. The coaxial epi-illumination device according to claim 5, wherein the circular shielding plate is disposed at a predetermined distance from the front surface of the light emitting surface toward the objective lens. The light emitting surface is circular with a diameter of 3.8 mm,
The coaxial epi-illumination device according to any one of claims 1 to 6, wherein the shielding means has a circular shape with a diameter of 1.0 mm and is disposed 0.7 mm before the light emitting surface. The coaxial incident illumination device according to any one of claims 1 to 4, wherein the shielding means is a circular opaque portion provided in the center of the light emitting surface. The shielding means is a hollow section having a circular cross section provided at the center of the light guide section,
5. The coaxial epi-illumination device according to claim 1, wherein the light guide section has a donut shape in cross section. 10. The telecentric optical system according to claim 1, wherein the illumination optical system is a telecentric optical system that converts the irradiation light emitted from the light emitting surface into parallel light on the exit surface side of the objective lens. Coaxial epi-illumination device.