JPS60217325A - Epidark use objective lens - Google Patents

Abstract

PURPOSE:To execute a sufficient epidark illumination even in case of an objective lens having a large aperture with simple constitution, by providing a ring- shaped hollow lens member of a negative refractive power between a ring- shaped condensing member of an epidark objective lens and an incident light side end of the objective lens. CONSTITUTION:A ring-shaped illuminating light supplied from a light source is reflected by a hole-opening reflecting mirror 12 provided diagonally in a microscope body and travels toward an objective lens 10. Subsequently, it is diverged by a ring-shaped lens member 1 of a negative refractive power provided in an objective lens barrel 11 in the vicinity of an incident light side end of the objective lens 10, and led to an object surface O by a ring-shaped concave surface reflecting mirror 2 being a ring-shaped condensing member provided in the vicinity of the tip of the objective lens 10.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a dark field illumination device in an epi-illumination microscope;
In particular, it relates to a so-called epidark objective lens.

(Background of the invention) Epidark illumination is an epi-illuminated microscope in which a ring-shaped light beam coaxial with the optical axis of the objective lens is supplied from around the objective lens, and this is condensed into a ring-shaped light beam provided near the tip of the objective lens. This is dark field illumination that is guided to the object plane by a member. Recently, the numerical aperture and working distance of objective lenses have become larger, and accordingly, the lens aperture of objective lenses has also become larger. For this reason, in conventional epidark illumination systems, it has become difficult to supply sufficient dark-field illumination light from around the objective lens.

(Objective of the Invention) The object of the present invention is to provide an objective lens for Ebi-Dark that has a simple structure and can provide sufficient epidark illumination even with an objective lens having a large aperture without changing the structure of the microscope body. It is about providing.

(Summary of the Invention) The present invention provides a ring-shaped condensing member disposed near the tip of an objective lens coaxially with the optical axis of the objective lens, and for illuminating an object surface with a ring-shaped light beam that wraps around the objective lens. In the objective lens for epidark, a ring-shaped hollow lens member having a negative refractive power is provided between the ring-shaped condensing member and the incident light side end of the objective lens. This ring-shaped lens member uses its negative refractive power to diverge the ring-shaped light flux supplied to the incident light side end of the objective lens, and expands the ring diameter of the ring-shaped light flux. The light is guided to a shaped light condensing member.

Therefore, even if the objective lens has a large aperture, the ring-shaped light beam can be guided to the tip of the objective lens, and sufficient dark-field illumination light can be supplied to the object surface by the ring-shaped condensing member.

In the present invention, in order to expand the aperture of the ring-shaped light beam, at least a ring-shaped lens member with negative refractive power is required, and this ring-shaped lens member with negative refractive power and a ring-shaped condensing member near the tip of the objective lens are required. It is possible to further provide a ring-shaped lens member with a positive refractive power between the two and convert the diverging light beam from the ring-shaped member with a negative refractive power into a parallel light beam parallel to the optical axis of the objective lens. According to this, the aperture of the ring-shaped light beam around the objective lens is not unnecessarily expanded, and even when the length of the objective lens is large, the aperture of the entire objective lens to accommodate the ring-shaped light beam is not unnecessarily enlarged. There is no need to increase the size, and it becomes possible to construct a compact objective lens for Evidark.

(Example) FIG. 1 is a schematic sectional view showing the structure of a first example of an objective lens for epidark according to the present invention. Ring-shaped illumination light supplied from a light source (not shown) is reflected by a perforated reflector (12) provided obliquely within the microscope main body, and is directed toward an objective lens (10).

The light is then diverged by a ring-shaped lens member (1) with a negative refractive power provided in the objective lens barrel (11) near the end of the incident light side of the objective lens (10). The light is guided to the object plane (0) by a ring-shaped concave reflecting mirror (2) as a ring-shaped condensing member. The negative refractive power ring-shaped member (1) is a hollow ring-shaped negative lens, as shown in the cross-sectional view (A) and plan view (B) of FIG. 2, and its inner diameter is equal to the effective aperture of the entrance surface of the objective lens. It is slightly larger. The ring-shaped light beam incident on the negative refractive power ring-shaped lens member (1) is subjected to a diverging effect here, and its aperture is expanded, and the ring-shaped concave reflecting mirror (2
), the aperture of the ring-shaped concave reflector can be increased, and even if the aperture of the objective lens (10) is quite large, it is possible to supply sufficient dark-field illumination light to the object plane (0).

FIG. 3 is a sectional view showing a schematic configuration of a second embodiment of the present invention, and members having the same functions as those in FIG. 1 are given the same reference numbers. In this second embodiment, a ring-shaped lens member (4) with a positive refractive power is provided between a ring-shaped lens member (3) with a negative refractive power and a ring-shaped concave reflector (5) as a ring-shaped condensing member. It is something that Here, a negative refractive power ring-shaped lens member (3) and a positive refractive power ring-shaped lens member (4)
) are respectively shown in Figure 4 (A) (B) and Figure 5 (A) (B).
) It has a shape as shown in . In each figure, (A) is a cross-sectional view, and (B) is a plan view. As shown in the figure, the positive refractive power ring-shaped lens member (4) has a larger aperture than the negative refractive power ring-shaped lens member (3), and the negative refractive power ring-shaped lens member (3) diverges. It receives a ring-shaped light beam and converts it into a parallel light beam. Therefore, in the configuration of the second embodiment, the cross-sectional shape of the ring-shaped light beam from the positive refractive power ring-shaped lens member (4) to the ring-shaped concave reflective member (5) as the ring-shaped condensing member is Since it is a ring with a constant radius, it is possible to maintain the overall aperture of the objective lens constant between these rings, and the overall aperture can be made compact. In addition, by combining ring-shaped lens members with negative refractive power and positive refractive power as in this embodiment, it is possible to correct aberrations in the illumination light flux, especially chromatic aberration, and provide a better dark-field illumination light flux. becomes possible.

The ring-shaped lens members (1), (3), and (4) with negative refractive power and positive refractive power used in each of the above examples are ordinary lenses as shown in FIGS. 2, 4, and 5, respectively. Since the center part of a negative lens or a positive lens is cut, it has the advantage of being relatively easy to manufacture with high precision.

In the above embodiment, a ring-shaped concave reflective member is used as the ring-shaped condensing member, but the present invention is not limited to this, and a ring-shaped hollow positive lens can also be used. In addition, the ring-shaped condensing member does not necessarily have to have a converging effect, but only has the effect of concentrating the ring-shaped light beam onto the object plane. It can also be a conical reflecting mirror or a convex ring-shaped reflecting surface with a diverging effect.

(Effects of the Invention) As described above, according to the present invention, even for a large-diameter objective lens, the ring-shaped light flux supplied around the objective lens can be efficiently transferred to the object surface without making any changes to the microscope body. bright dark-field illumination. Moreover, since a ring-shaped lens member with a negative refractive power is used, the width of the ring-shaped light beam becomes large, which is advantageous in the case of a low-magnification objective lens with a wide actual field of view. Furthermore, the aperture of the ring-shaped light beam at the tip of the objective lens can be made larger than that of the conventional one, which is advantageous for increasing the working distance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic configuration of a first embodiment according to the present invention, FIGS. 2(A) and 2(B) are a sectional view and a plan view of a negative refractive power ring-shaped lens member used in the first embodiment, FIG. 3 is a schematic sectional view showing the configuration of a second embodiment according to the present invention, and FIG.
Figures (A) and (B) and Figure 5 (A) and (B) are respectively
FIG. 3 is a cross-sectional view and a plan view of a negative refractive power ring-shaped lens member and a positive refractive power ring-shaped lens member used in Examples. [Explanation of symbols of main parts] 1.3...Negative refractive power ring-shaped lens member 2.5...
Ring-shaped condensing member 4...Positive refractive power Ring-shaped lens member 10...Objective lens O...Object plane Applicant: Nippon Kogaku Kogyo Co., Ltd. Agent Takao Watanabe

Claims (1)

[Claims] An epidark objective lens having a ring-shaped condensing member disposed near the tip of the objective lens coaxially with the optical axis of the objective lens for illuminating an object plane with a ring-shaped light flux that wraps around the objective lens. 1. An objective lens for epidark, characterized in that a ring-shaped hollow lens member having a negative refractive power is provided between a condensing member and an end of the objective lens on the incident light side.