JPH0241603Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an objective lens capable of epidark illumination for performing dark field observation in an epi-illumination microscope.

Epidark illumination is an epi-illuminated microscope in which a ring-shaped light beam whose center coincides with the optical axis of the objective lens is supplied from around the objective lens. It focuses light onto an object using a member.
It is detailed in Publication No. 47605. Generally, when performing epidark illumination, a dedicated objective lens is used for this purpose, but in recent years the effective diameter of the objective lens has become larger as the NA of the objective lens has become higher and the working distance has become longer. It is becoming difficult to perform effective epidark illumination using the ring-shaped light beam provided by the ring-shaped light beam supply system that is standard equipment in epi-illumination microscopes. For this reason, if the configuration is such that the shape of the ring-shaped light beam is changed depending on the effective diameter of the attached objective lens, the structure of the microscope main body will inevitably become complicated.

An object of the present invention is to provide an objective lens that can perform effective epidark illumination even when it has a large aperture without changing the structure of the microscope main body.

In order to condense a ring-shaped light beam that wraps around the objective lens system, the present invention includes a ring-shaped condensing member placed near the tip of the objective lens system so that the optical axis of the objective lens system coincides with the optical axis. an objective lens comprising: a ring-shaped outward deflection member for outwardly deflecting the ring-shaped light beam; and a ring-shaped light beam from the ring-shaped outward deflection member, the ring-shaped outward deflection member having a larger aperture than the ring-shaped outward deflection member. a ring-shaped inward deflection member that directs the light toward the ring-shaped light condensing member, and the ring-shaped light condensing member and the ring-shaped inward deflection member have approximately the same diameter.

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a schematic cross-sectional view of a first embodiment of the present invention. Illumination light flux from a light source (not shown) reflected by a perforated reflecting mirror 1 provided obliquely within the microscope body enters an objective lens 10 as a ring-shaped light flux. The objective lens 10 has an objective lens system 12 at the center within its lens barrel 11. Further, a first annular prism 13 having a triangular cross section is provided as a ring-shaped outward deflection member near the barrel surface 11a of the objective lens.
However, a second annular prism 14 whose cross-sectional shape is a triangle in the opposite direction to that of the first annular prism is provided as a ring-shaped inward deflection member at a substantially intermediate position of the lens barrel.
is provided. A ring-shaped concave reflecting mirror 15 is arranged near the tip of the objective lens system 12 as a ring-shaped condensing member. Here, the first annular prism 13, the second annular prism 14, and the ring-shaped concave reflecting mirror 15 are all included in the objective lens system 12.
It is arranged concentrically with the optical axis 12a of. The effective diameter of the first annular prism 13 is approximately the same as the effective diameter of the apertured reflector so that the ring-shaped light beam from the apertured reflector 1 can be sufficiently received, and the effective diameter of the second annular prism 14 is is larger than that of the first annular prism 13 and approximately the same as the effective diameter of the ring-shaped concave reflecting mirror 15.

Figure 2 shows the first and second annular prisms 13 and 14.
FIG. 2 is a perspective view showing the shape and function of the present invention, and each cross-sectional shape is shown by a hatched portion for ease of understanding. As shown in the figure, the ring-shaped light beam is directed outward by the first annular prism 13, that is, by the objective lens system 12.
The light beam is refracted outward in the radial direction with respect to the optical axis 12a, and enters the second annular prism 14 as a ring-shaped light beam with a large diameter. Since the ring-shaped light beam is refracted inward in the radial direction with respect to the optical axis 12a by the second annular prism 14, it becomes a light beam almost parallel to the optical axis 12a and is reflected by the ring-shaped concave reflecting mirror 15.
, and is subjected to the convergence effect here to be isotropically focused on the object plane O with respect to the optical axis 12a. Since the illumination light flux incident on the object surface has a fairly large angle with respect to the optical axis 12a of the objective lens system, the direct reflected light on the object surface O does not enter the objective lens system 12. Only the scattered or diffracted light at the object plane O enters the objective lens system 12, forming a dark-field image.

According to this embodiment, the ring-shaped light beam from the apertured reflector 1 installed obliquely within the microscope body can be expanded into a ring-shaped light beam with a larger radius around the objective lens system. also big
Effective epidark illumination flux can be supplied to objective lens systems with NA or longer working distances. Note that if the prism apex angles of the first annular prism 13 and the second annular prism 14 are made equal, the prism can be achromatized and the configuration can be made the most compact.

In the above embodiment, the ring-shaped light beam is expanded by the refraction effect of the two annular prisms, but the ring-shaped light beam can be similarly expanded by the reflection effect. FIG. 3 is a schematic cross-sectional view of the objective lens 10' of the second embodiment. In this embodiment, a ring-shaped prism having two annular reflecting surfaces with equal inclination angles is used, and in the drawings, members having the same functions as those in the first embodiment are given the same numbers. Further, FIG. 4 is a perspective view showing the shape and function of the ring-shaped prism 16 in this embodiment, and the cross-sectional shape is shown by the hatched part.

In this embodiment, the barrel mounting surface 1 of the objective lens barrel 11 is
A ring-shaped prism 16 having a parallelogram cross section is provided near the ring-shaped concave reflecting mirror 1a, and the diameter of the ring-shaped light beam is expanded by this prism.
5. That is, the ring-shaped prism 16
has an entrance surface 16a and an exit surface 16d that are parallel to each other, and a first reflection surface 16b and a second reflection surface 16c that are parallel to each other at an angle of 45 degrees. The ring-shaped light beam from the diagonally installed perforated reflector 1 is directed to the incident surface 16.
the objective lens system 12 at the first reflective surface 16b through the
is reflected outward in the radial direction with respect to the optical axis 12a of
6d, it reaches a ring-shaped concave reflecting mirror 15 as a ring-shaped condensing member. As in the first embodiment, the object plane O is uniformly illuminated by the ring-shaped concave reflecting mirror 15 with a ring-shaped light beam having a large angle.

In this embodiment, the first reflective surface 16b of the ring-shaped prism 16 functions as a ring-shaped outward deflection member, and the second reflective surface 16c functions as a ring-shaped inward deflection member.

Even with this configuration, the ring-shaped light beam from the apertured reflector can be expanded around the objective lens system, allowing effective epidark illumination for objective lens systems with large NA and long working distance. It is. Furthermore, in this embodiment, since the ring-shaped outward and inward deflecting members are composed of one member,
It has a simpler configuration. Further, the first and second reflective surfaces 16b, 1 of the ring-shaped prism 16 are parallel to each other.
It goes without saying that 6c does not necessarily have to have an inclination angle of 45 degrees, and if both reflective surfaces are configured to allow so-called total reflection, there is no need for special reflective treatment such as silver deposition.

In each of the above embodiments, the illumination light beam is condensed accurately onto the object surface, but in order to more uniformly illuminate the object surface, a lemon skin surface is used in the optical path of the illumination light beam of the objective lens in the present invention. It is desirable to provide a diffusely transmitting surface or a diffusely reflecting surface. Further, the ring-shaped condensing member is not limited to a concave reflecting mirror, but may also be a ring-shaped lens.

FIG. 5 is a schematic sectional view of a third embodiment of the present invention, the basic configuration of which is the same as the first embodiment shown in FIGS. 1 and 2. In the figure, members having the same functions as those in the previous embodiment are given the same numbers.
In this embodiment, the entrance surface 13a of the first annular prism 13 as a ring-shaped outward deflection member is a lemon skin surface, and the ring-shaped light beam is subjected to a desired diffusion effect on this surface. After this ring-shaped light beam is refracted by the second annular prism 14 as a ring-shaped inward deflection member, it is focused onto the object plane by a ring-shaped positive lens 15' as a ring-shaped condensing member. On the object plane O, the effect of the diffusion surface 13a provides bright, uniform illumination with little flare, similar to the device disclosed in Japanese Utility Model Publication No. 56-47605. The position of the diffusing surface may be the exit surface of the first annular prism 13 or the prism surface of the second annular prism 14, but the farther it is from the ring-shaped condensing member, the less likely it is that unnecessary illumination light will be supplied to the object surface. desirable. For example, in the second embodiment shown in FIG. 3, it is most desirable to provide the entrance surface 16a of the ring-shaped prism 16 with a diffusing surface.

As described above, according to the present invention, it is possible to expand the diameter of the ring-shaped light beam around the objective lens to a desired value. Also, epidark illumination can be performed efficiently without changing the configuration of the microscope main body.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the first embodiment of the present invention, Fig. 2 is a perspective view of a part of the optical system of the first embodiment, Fig. 3 is a sectional view of the second embodiment, and Fig. 4 is a sectional view of the second embodiment. A perspective view of a part of the optical system of the embodiment, and FIG. 5 is a sectional view of the third embodiment. Explanation of symbols of main parts, 13, 16b... Same ring-shaped outward deflection member, 14, 16c... Ring-shaped inward deflection member, 15, 15'... Ring-shaped condensing member, 12... Objective lens System, 1...Perforated reflector.

Claims (1)

[Scope of utility model registration request] In an objective lens having a ring-shaped condensing member disposed near the tip of the objective lens system so as to align the optical axis with the optical axis of the objective lens system, in order to condense a ring-shaped light beam that wraps around the objective lens system. a ring-shaped outward deflection member for deflecting the ring-shaped light beam outward; and a ring-shaped outward deflection member having a larger aperture than the ring-shaped outward deflection member to deflect the ring-shaped light beam from the ring-shaped outward deflection member into the ring-shaped outward deflection member. 1. An objective lens for epidark, comprising a ring-shaped inward deflection member directed toward a condensing member, the ring-shaped condensing member and the ring-shaped inward deflection member having substantially the same aperture.