JPS5816214A - Annular luminaire - Google Patents

Abstract

PURPOSE:To vary an image of an annular light source in size easily by arranging an optical element which has a conic surface coaxial with an optical axis between a collector lens and the position where the image of the light source is formed by the collector lens. CONSTITUTION:A conic prism 6 which has a conic surface coaxial with an optical axis and having a large vertical angle is arranged behind a collector lens 2 while having its bottom surface opposed to the collector lens 2. An image- forming lens 7 is arranged between the prism and an annular aperture stop. Therefore, luminous flux from a light source 1 strikes the prism 6 after passing the collector lens 2, and then strikes after being refracted by the prism 6 to form an annular light-source image 8 in the aperture of the annular aperture stop 5. Thus, a spot image of the light source 1 is converted into the annular image 8.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an annular illumination device used in field microscopes and the like.

As shown in FIG. 1, for example, a conventional annular illumination device for a phase contrast microscope includes a light source 1, a collector lens 2, and a condenser whose front focal point is aligned with the position where a light source image 3 is formed by the collector lens 2. a lens 4 and an annular aperture diaphragm 5 disposed near the front focal point of the collector lens 4
However, most of the light from the light source image 3 was blocked by the annular aperture stop 5, and only a small portion passed through the aperture of the annular aperture stop 5, so it was not very bright and efficient. It was bad. Therefore, in order to improve the efficiency, for example, according to Japanese Patent Publication No. 26-456, an illumination device using an aspherical lens having a special cross section so that the image of a point light source becomes annular has been considered. Since the surface shape is aspherical, it is difficult to manufacture, and it is troublesome to change the size of the annular light source image.

In view of the above problems, the present invention aims to provide an annular illumination device that is bright, efficient, easy to manufacture, and easy to change the size of an annular light source image. 6 is explained based on the embodiment shown in FIG.
7 is a conical prism arranged behind the collector lens 2 with its bottom surface facing the collector lens 2 side, is coaxial with the optical axis, and has a conical surface whose top is a dog; 7 is a conical prism 6 and an annular aperture; This is an imaging lens placed between the aperture 5 and the aperture 5.

Since the annular illumination device according to the present invention is constructed as described above, the Jurou luminous flux exiting the light source 1 passes through the collector lens 2 and then enters the conical prism 6, where it is refracted into a cone-shaped beam. After becoming a light beam, the imaging lens 7
The light is incident on the aperture of the annular aperture stop 5 by the imaging lens 7 as an annular light source image 8 . Therefore, according to the present illumination device, the point light source 1 can be easily converted into an annular light source image 8.
It can be converted to . Furthermore, since most of the light from the annular light source image 8 passes through the aperture of the annular aperture stop 5, it is bright and efficient. Further, since the conical prism 6 and the imaging lens 7 have a conical surface and a spherical surface, respectively,
It is also easy to produce.

Next, regarding the necessary size of the light source 1, we will discuss the above conventional example (first example).
1) and this embodiment (FIG. 2) will be compared.

Since the size of the illumination field to be illuminated is related to the opening angle of the light flux incident on the condenser lens 4, let that angle be α. Furthermore, the sizes of the light source images 3 and 8 in FIGS. 1 and 2 are respectively Y and Y2 (where Y2 may be considered to be the width of the aperture of the annular aperture stop 5.

), the size of the light source 1 is Yo, and the acceptance angles required by each collector lens 2 are β1 and β2, respectively.
The following formula holds.

Therefore, it follows from equations (1) and (2). And, in a normal phase contrast microscope,
It can be very convoluted. In addition, in this illumination device, the magnification of the light source 1 may be small, so even something close to a point light source can be easily turned into an annular light source image.
High brightness point light sources such as xenon can be used.

First, conversion of the size and diameter of the annular light source image 8 will be explained. That is, as shown in FIG. 3, the circular prism 6 is brought closer to the collector lens 2, and the imaging lens 7
If an imaging lens 9 with a long focal length is placed instead, the distance between the conical prism 6 and the imaging lens 9 will become longer, so the opening angle of the cone-shaped light beam created by the circle; If is constant, the size (diameter) of the annular light source image 8 will be large. Therefore, according to this illumination device, the size of the annular light source image 8 can be easily changed, so the size of the annular light source image 8 can be changed according to the magnification, N, and A of the objective lens. It's convenient.

FIG. 4 shows a second embodiment, in which a reflective optical element consisting of a conical mirror 10 and an annular mirror 1 is used instead of the conical prism 6. Unlike the conventional annular light source, no chromatic aberration occurs, so a better annular light source image 8 can be created. Further, FIG. 5 shows a third embodiment, in which a prism 12 having a mortar-shaped top and a flat bottom is used instead of the conical prism 60. 6 shows a fourth embodiment, in which a conical mirror 13 is used in place of the conical prism 6, and in this case as well, it is similar to the second example above. Similarly, it has the advantage that chromatic aberration does not occur. Furthermore, FIG. 7 shows a fifth embodiment, in which a conical prism 14 with a small apex angle is used instead of the conical prism 60, and the light exits the light source 1 and passes through the collector lens 2. The light enters the bottom surface of the conical prism 14, is once totally reflected on the side surface of the prism 14, and then exits from the opposite side surface, thereby forming a silicone-shaped light beam.

As mentioned above, the annular illumination device according to the present invention has very important advantages for this type of illumination device, such as being bright, efficient, easy to manufacture, and easy to change the size of the annular light source image. ing.

It goes without saying that the annular illumination device according to the present invention can be directly applied to high %llH&microscopes, dark field microscopes, and the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical system of a conventional annular illumination device, FIG. 2 is a diagram showing an optical system of an embodiment of an annular illumination device according to the present invention, and FIG. 3 is a diagram showing the size of an annular light source image in the above embodiment. Figures 4, 5, and 6 show the optical system when the angle is converted.
Figures 7 and 7 are respectively second. It is a figure which shows the optical system of a 3rd, 4th, and 5th Example. 1. Light source, 2. Collector lens, 4. Paired proboscis lens, 5. Annular aperture diaphragm, 6. Conical prism.
7... Imaging lens, 8... Annular light source image.

Claims (1)

[Claims] In an annular illumination device comprising at least a light source, a collector lens, and a condenser lens, an optical element having a conical surface coaxial with the optical axis is disposed between the collector lens and the light source image forming position on the collector lens, An annular illumination device characterized in that a luminous flux that exits the light source and enters the optical element after passing through the collector lens is refracted or reflected by the conical surface to form an annular light source image.