JP2007133435A - Microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscope which adopts a compact illuminating device adopting an LED as a light source, achieving observation good in resolution and sensitivity, also obtaining uniform illumination free from an illumination spot, having high efficiency of utilizing light and making power consumption low. <P>SOLUTION: Light from the illuminating device 50 is made parallel beams by a field lens 40 and reflected by a dichroic mirror 41 to illuminate a sample surface through an objective 42. Transmitted light or fluorescence from the sample surface is made to form an image on an image forming surface by an image forming lens 43 through the objective 42 and the dichroic mirror 41 so as to be observed. The illuminating device 50 is arranged so that the emitting end of a rod integrator 3 may agree with the field stop position of the microscope. Thus, the image of a uniform plane light source free from irregular luminance occurring at the emitting end of the rod integrator 3 is formed on the observation surface of the sample so as to achieve critical illumination, thereby performing observation in such a state where the depth of focus is shallow in comparison with Koehler illumination. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illuminating device using a plurality of LED lamps or LED chips as a light source used in an optical apparatus such as a microscope, an exposure apparatus, a projector, and a spectroscopic instrument, and a microscope using the illuminating apparatus.

  Conventional optical devices use almost a single light source, and when the light intensity is increased, the intensity of the light source itself is increased, that is, a large light source is employed. As means for increasing the light intensity, Patent Document 1 discloses a rod integrator provided with a partial introduction portion, and Patent Document 2 discloses a rod integrator having the same number of incident end faces as the light source. Both of these are expensive because of complicated processing on the incident end face of the rod integrator. Due to recent technological advances, inexpensive and high-brightness LED chips that can be used as LED lamps have been developed, and their application fields are expanding.

  A conventional fluorescent microscope uses a large lamp such as a mercury lamp, selects only light having a wavelength used as excitation light with a filter, and uses only a small part of the light emitted from the light source. . Although the above problem is solved when an LED is used, a high-brightness LED has been developed, but the amount of light is insufficient when a single LED is used. However, when multiple are used, uneven illumination occurs. In general, the Koehler illumination method is widely used as a microscope illumination method for both transmission observation and fluorescence observation. The critical illumination method for forming an image of a light source on a sample has not been widely used in spite of many advantages such as high resolution in the depth direction. This is because when the light source part of the illumination lamp is imaged, the filament and arc image of the lamp appear in the sample, resulting in illumination spots. To solve this problem, there is a method of inserting a scatterer in order to eliminate this illumination spot. For example, a frost bulb or a fluorescent tube is used.

  As an illumination device using LEDs, Patent Document 3 discloses a rod integrator in which a plurality of LEDs are used as a basic unit constituting an LED display, and in order to avoid interference with adjacent units and to equalize light brightness. And the use of light pipes. As a microscope illumination device using LEDs, Patent Document 4 describes a method of directly diffusing a microscope observation sample using a plurality of LEDs, a diffractive optical element, and a lens. Further, as a microscope illumination method, Patent Document 5 describes a method of easily switching between a microscope Kohler illumination method and a critical illumination method by detaching and inserting a lens group from an optical system.

JP-A-5-72627 JP 2000-75407 A Japanese Patent Laid-Open No. 10-319873 JP 2002-189174 A Japanese Patent Laid-Open No. 10-232353

By the way, with a single LED lamp or LED chip, there is a problem of insufficient light quantity depending on the application, and when a plurality of LED lamps are mounted at a high density, heat dissipation is also a problem. Further, in the conventional microscope illumination method, the scattered light from the scatterer spreads in all directions, and only a part of this can be used for sample illumination, so a sufficient amount of light cannot be secured. In other words, there was a problem of darkness. In addition, since the scatterer is thicker than necessary, there is a problem that the resolution in the thickness direction does not increase even if the scatterer is regarded as a pseudo-planar light source and an image is formed on the sample. In particular, when a critical illumination method is employed in fluorescence microscope observation, it is expected that both sensitivity and resolution will be increased, but it is not popular due to the above problems and price problems.
An object of the present invention is to adopt a microscope that employs an LED as a light source, enables observation with high resolution and sensitivity, is uniform with no illumination spots, has high light utilization efficiency, and has a low power consumption and compact illumination device. It is to provide.

In order to achieve the above object, a microscope according to the invention of claim 1 is a microscope that illuminates a sample with light from an illuminating device and images and observes transmitted light or fluorescence from the sample,
The illumination device includes a light source comprising a plurality of LEDs for supplying illumination light, means for converting incident light from the light source into a planar light source, and a critical illumination optical system that forms an image of the planar light source on a sample and performs critical illumination. The planar light source is provided at a field stop position.

  According to a second aspect of the present invention, in the first aspect of the present invention, the position of the planar light source is set to a field stop position in a state where the illumination device maintains a distance between the light source composed of the plurality of LEDs and the means for forming the planar light source. Alternatively, illumination switching means for switching between Kohler illumination and critical illumination by moving to the aperture stop position is provided.

  According to a third aspect of the present invention, in the first or second aspect, the light source composed of the plurality of LEDs is disposed on the thermally conductive electrode substrate and the thermally conductive electrode substrate, and the lead frame on which the LED chip is mounted is disposed on the thermally conductive substrate. A plurality of electrodes connected directly and electrically to a conductive electrode substrate, and one electrode of each LED chip is connected to a wiring pattern insulated from the thermally conductive electrode substrate by an insulating film by a bonding wire. And an LED lamp.

  According to a fourth aspect of the present invention, in the first or second aspect, the light source comprising the plurality of LEDs is electrically and thermally mounted by directly mounting a plurality of LED chips on the thermally conductive electrode substrate and the thermally conductive electrode substrate. An LED chip assembly in which one electrode of each LED chip is directly connected to a wiring pattern insulated from the thermally conductive electrode substrate by an insulating film by a bonding wire, and the LED chip assembly And a condensing lens for condensing the luminous flux from the light source.

  According to a fifth aspect of the present invention, in the third or fourth aspect, a heat radiating means is thermally coupled to a surface of the thermally conductive electrode substrate opposite to a surface on which the LED lamp or the LED chip is disposed. And

  According to a sixth aspect of the present invention, in the first or second aspect, the means for converting the incident light from the light source into a planar light source is formed of a thin film scatterer.

  A seventh aspect of the present invention is the method according to the first or second aspect, wherein the means for converting the incident light from the light source into a planar light source makes a light beam emitted from a plurality of LEDs incident on an incident end face and superimposes the light beam on the inside. It is composed of a rod integrator that adds the light intensities of the LEDs and generates a planar light source on the exit end face.

  The invention of claim 8 is characterized in that, in claim 7, the lighting devices are cascade-connected.

According to the microscope of the present invention, when a rod integrator is used, critical illumination without uneven illumination becomes possible, and when a thin film scatterer is used instead of the rod integrator, it can be manufactured at a low cost. Furthermore, it is easy to adapt based on a widely used conventional microscope, and it is possible to easily switch between observation with a deep focal depth and observation with a shallow focal depth during observation.
Furthermore, according to the illumination device of the microscope, it can be used as an illumination device in which light beams from a plurality of LED lamps are superimposed by a rod integrator and the light intensity is added. The illumination device becomes a uniform light source without illumination unevenness. In addition, by thermally coupling the lead frame on which the LED chip is mounted, or the LED chip itself to the thermally conductive electrode substrate, the heat dissipation effect is improved and a large current can flow through the LED, increasing the light intensity. At the same time, deterioration due to heat generation can be suppressed and the life can be extended.

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

  FIG. 1 is a conceptual diagram illustrating the principle of an illumination device applied to a microscope of the present invention. Light beams from the plurality of LED lamps L1 to Ln are condensed on the incident end face of the rod integrator. At this time, the LED lamps L1 to Ln are arranged so that the light beam is incident within the light receiving angle of the rod integrator. The light beam incident on the incident end of the rod integrator is multiple-reflected inside the rod integrator, and the light beams from the individual LED lamps are superimposed and added, and are made uniform at the same time. When the directivity of each LED lamp is sharp, it is sufficient to arrange the optical axis of the LED lamp, that is, the emission direction, toward the incident end surface of the rod integrator. When the directivity is dull, the light from each LED lamp is condensed on the incident end face of the rod integrator using a lens or a mirror. In the present invention, the number of LED lamps spatially arranged is limited by the limitation of the light receiving angle of the rod integrator. Therefore, when the amount of light is further insufficient, the illumination device is connected in multiple stages (cascade) as shown in FIG. 2 to increase the amount of light by increasing the number of LED lamps.

  An embodiment of an illumination apparatus applied to the microscope of the present invention will be described. FIG. 3 is a block diagram of the first embodiment. FIG. 4 is a diagram showing an assembled state of the LED lamp 1 to the thermally conductive electrode substrate. In this embodiment, a plurality of LED lamps 1 are arranged on a thermally conductive electrode substrate 2 made of, for example, a copper plate, and are installed so that the optical axis of the LED lamp 1 faces the incident end face of the rod integrator 3. A lead frame 11 on which one of the cathode and anode electrodes of the LED chip 10 of each LED lamp 1 is mounted is electrically connected to the thermally conductive electrode substrate 2. The fixing surface of the LED lamp 1 of the heat conductive electrode substrate 2 is formed in a concave spherical surface, and the insulating film 4 is affixed. The lead frame 11 penetrates the insulating film 4 and is electrically connected to the heat conductive electrode substrate 2. The other lead frame 12 is connected to a wiring pattern 7 provided on the surface of the insulating film 4. In this embodiment, the heat conductive electrode substrate made of copper is connected by soldering, but an adhesive that can conduct electricity and heat well can also be used. By this thermal coupling, the heat generated from the LED chip 10 can be efficiently released.

  In order to release heat from the heat conductive electrode substrate 2, the heat conductive electrode substrate is provided with heat radiating means. One specific example of the heat dissipating means is shown in FIG. In this example, a Peltier element 8 is disposed on the back surface of the thermally conductive electrode substrate 2, a radiator 5 is provided on the Peltier element 8, and each is thermally coupled, and the radiator 5 is further cooled by a cooling fan 6. Has been. In this embodiment, 16 bullet-type LED lamps 1 having a sharp directivity with a viewing angle of ± 6 degrees are used and arranged in a grid pattern. Any number of LED lamps 1 having other shapes and performances can be arranged arbitrarily.

  FIG. 5 shows a configuration diagram of a modification of the first embodiment. In this embodiment, the optical axes of a plurality of LED lamps 1 are arranged on a flat thermally conductive electrode substrate 2 so as to be parallel to each other. Between the LED lamp 1 and the rod integrator 3, a condenser lens 9 that condenses the luminous flux of each LED lamp 1 at the incident end of the rod integrator 3 is installed. According to the present embodiment, it is not necessary to adjust the optical axis of each LED lamp 1 to face the incident end of the rod integrator 3. Since the luminous flux can be guided, it is effective when the directivity of the LED lamp 1 is dull.

  The rod integrator 3 is an optical propagating body in which a light beam introduced from an incident end repeats multiple reflections and propagates to the exit end. In the rod integrator 3 shown in FIG. 6, a clad 30 formed of an optical material having a low refractive index surrounds a core body 31 formed of an optical material having a high refractive index, like an optical fiber. In the rod integrator 3 shown in FIG. 7, the core 31 is formed of a glass rod or a plastic rod that can provide ambient air with a cladding function and allow total reflection on the surface. The rod integrator 3 shown in FIG. 8 is a mirror rod made of a mirror such as a glass or plastic surface coated with a metal such as aluminum. The rod integrator 3 shown in FIG. 9 is a typical example of a structure in which the rod integrator is formed in a tapered shape in which the cross-sectional area decreases from the incident end 3A toward the exit end 3B. The tapered rod integrator acts to reduce the light flux and increase the light intensity. The shape narrowed down to a taper can be used to fabricate a fiber light source by optically coupling the exit end to an optical fiber. As an application example of the tapered rod integrator, a point light source shown in FIG. 10 or a linear light source shown in FIG. 11 can be created. A point light source can easily obtain parallel light by adding a lens. In addition, the tapered shape is also applied to the structure of only the core of FIG. 7 or the structure in which the core surface of FIG. 8 is mirrored. The shape of the rod integrator is not limited to a cylinder or a prism, and can be a curved line other than a straight line.

The configuration of the incident end of the rod integrator 3 will be described. At the incident end of the core body 31 of the rod integrator 3, as shown in FIG. 12, a condensing lens 33 for enlarging the light receiving angle is arranged in contact with the incident end surface, or formed on the convex lens 34 shown in FIG. ing. FIG. 14 shows a structure in which the core material of the core body 31 of the rod integrator 3 and the LED lamp 1 are integrated by molding.
The configurations of the entrance end and the exit end of these rod integrators 3 can be selectively applied to the above-described embodiments such as the structure with or without the cladding 30 and the mirror 32.

  A second embodiment of the lighting device will be described. FIG. 15 is a perspective view of an LED chip integrated body constituting a second embodiment of the lighting device, and FIG. 14 is a partial cross-sectional view of the LED chip integrated body. In the LED chip integrated body, a plurality of LED chips 9 are directly mounted on the thermally conductive electrode substrate 2 by adhesion and are electrically and thermally connected. An insulating film 4 provided with a wiring pattern 7 is pasted on the surface of the thermally conductive electrode substrate 2. The other electrode of each LED chip 9 is connected to the wiring pattern 7 via a chip resistor 14 by a bonding wire 13. Although not shown in the drawing, the whole or at least the LED chip 9 and the bonding wire 13 are covered with a transparent resin for protection.

  The LED chip integrated body can be used in place of the aforementioned LED lamp. In addition, many LED chip assemblies are not only excellent in heat dissipation efficiency because the LED chip 7 is directly thermally coupled to the thermally conductive electrode substrate 2 without a lead frame, but are also suitable for mass production.

  An embodiment of the microscope of the present invention that employs the above-described illumination device will be described. FIG. 17 is a schematic diagram of a microscope. The microscope illuminates the sample surface through the objective lens 42 by making the light from the illumination device 50 into parallel light by the field lens 40 and reflecting it to the dichroic mirror 41. The transmitted light or fluorescence from the sample surface is imaged on the imaging surface by the imaging lens 43 through the objective lens 42 and the dichroic mirror 41 and observed.

  The illumination device 50 is arranged so that the exit end of the rod integrator 3 matches the field stop position of the microscope. As a result, a uniform planar light source having no luminance unevenness generated at the exit end of the rod integrator 3 is imaged on the observation surface of the sample, thereby realizing critical illumination. As a result, critical illumination without illumination unevenness is possible, and observation with a shallower depth of focus is possible compared to Koehler illumination. This is because the focal depth of observation is proportional to the product of the focal depth of illumination and the focal depth of imaging.

  The present invention is applicable to both transmitted light illumination and epi-illumination such as fluorescence observation. Since the depth of focus is shallow, an optical slice image can be obtained. It is also possible to acquire a plurality of optical slice images while shifting the observation surface in the depth direction, and reconstruct a three-dimensional stereoscopic image from these optical slice images by an image processing technique. Further, the exit angle of the rod integrator can adjust the refractive index of the material, so that it can be transmitted to the field lens arranged in front of the rod integrator without loss of light energy.

  Illumination switching means for moving the illumination device 50 to the field stop position and the aperture stop position in the direction of the arrow shown in the figure is provided. The illumination switching means switches the Kohler illumination and the critical illumination by moving the position of the exit end of the rod integrator 3 to the field stop position or the aperture stop position while keeping the distance between the light source 1 and the rod integrator 3. Koehler illumination is achieved by matching the exit end of the rod integrator to the aperture stop position.

It is desirable to image a thin planar light source generated at the exit end of the above rod integrator on the sample observation surface, but in order to produce inexpensively, a thin film scatterer is simply placed at the aperture stop position. Critical lighting can be realized. The thin-film scatterer has a thinner scattering layer than the conventional frosted glass or opal glass, and the scattering angle can be limited. Thin film scatterers using surface relief hologram technology that can be used for this purpose, for example, “Light Shaping”, a product name made by Physical Optics Corporation (CA.USA)
There is “Diffuser”.

It is a conceptual diagram explaining the principle of an illuminating device. It is a figure which shows the application example which connected the illuminating device in cascade. It is a block diagram of 1st Example of an illuminating device. It is a figure which shows the assembly | attachment state to the heat conductive electrode board | substrate of an LED lamp. It is a block diagram which shows the modification of 1st Example. It is a figure which shows the Example of a rod integrator. It is a figure which shows the modification of a rod integrator. It is a figure which shows the other modification of a rod integrator. It is a figure which shows the other modification of a rod integrator. It is a figure which shows the example of the point light source using a taper-shaped rod integrator. It is a figure which shows the example of the linear light source using a taper-shaped rod integrator. It is a figure which shows the Example of a rod integrator light reception angle expansion means. It is a figure which shows the modification of a rod integrator light reception angle expansion means. It is a figure which shows the structure which integrated LED by the molding at the incident end of the rod integrator. It is a perspective view of a LED chip integrated body. It is a fragmentary sectional view of a LED chip integrated body. It is a schematic diagram of the microscope of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... LED lamp, 2 ... Thermally conductive electrode board, 3 ... Rod integrator, 4 ... Insulating film, 5 ... Radiator, 7 ... Wiring pattern, 10 ... LED chip, 11, 12 ... Lead frame, 30 ... Cladding body, 31 ... Core body, 32 ... Mirror, 50 ... Lighting device

Claims (8)

A microscope that illuminates a sample with light from an illuminating device and images and observes transmitted light or fluorescence from the sample,
The illumination device includes a light source comprising a plurality of LEDs for supplying illumination light, means for converting incident light from the light source into a planar light source, and a critical illumination optical system that forms an image of the planar light source on a sample and performs critical illumination. A microscope characterized in that the planar light source is provided at a field stop position. With the illumination device maintaining a distance between the light source composed of the plurality of LEDs and the planar light source, the position of the planar light source is moved to the field stop position or the aperture stop position to achieve the Kohler illumination and the criticality. The microscope according to claim 1, further comprising illumination switching means for switching illumination. The light source composed of the plurality of LEDs is disposed on the thermally conductive electrode substrate and the thermally conductive electrode substrate, and a lead frame on which the LED chip is mounted is directly and electrically connected to the thermally conductive electrode substrate. And a plurality of LED lamps having one electrode of each LED chip connected to a wiring pattern insulated from the thermally conductive electrode substrate by an insulating film by bonding wires. The microscope according to 1 or 2. The light source composed of the plurality of LEDs includes a heat conductive electrode substrate, and a plurality of LED chips mounted directly on the heat conductive electrode substrate and directly connected electrically and thermally, and one of the LED chips. An LED chip integrated body connected to a wiring pattern insulated from the thermally conductive electrode substrate by an insulating film by a bonding wire, and a condensing lens for condensing a light beam from the LED chip integrated body. The microscope according to claim 1 or 2, wherein the microscope is provided. The microscope according to claim 3 or 4, wherein a heat radiating means is thermally coupled to a surface of the thermally conductive electrode substrate opposite to a surface on which the LED lamp or the LED chip is disposed. 3. The microscope according to claim 1, wherein the means for converting the incident light from the light source into a planar light source is formed of a thin film scatterer with a limited scattering angle. The means for converting the incident light from the light source into a planar light source makes a light beam emitted from a plurality of LEDs incident on the incident end face, superimposes the light flux inside, adds the light intensity of each LED, and forms a planar light source on the outgoing end face. The microscope according to claim 1, wherein the microscope is configured by a rod integrator that generates The microscope according to claim 7, wherein the illumination devices are cascade-connected.

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