JPH0766107B2 - Variable viewing angle observation optical system - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a microscope observation barrel, and more particularly to an observation optical system capable of changing a depression angle.

[Background of the Invention]

Conventionally, various observation lens barrels for microscopes capable of adjusting the depression angle for observation are known, for example, U.S. Pat. No. 4,299,43.
No. 9 and Japanese Patent Laid-Open No. 59-159119 are known. In these configurations, the optical path for guiding the light beam from the objective lens to the eyepiece is bent in various directions and is not a right angle, but an angle, so there are restrictions on the combination of optical elements such as relay lenses and prisms. In many cases, the arrangement of each element and the optical path length are limited, making it difficult to achieve a compact structure. Further, since the optical path is not at a right angle, it is difficult to adjust the optical axis, and there is a drawback that the difficulty in manufacturing and processing the lens barrel becomes high.

[Object of the Invention]

An object of the present invention is to provide an observation optical system having a variable depression / viewing angle, which is easy to process and adjust and has a small configuration.

[Outline of Invention]

The observation optical system according to the present invention guides a part of the image-forming light beam from the objective lens to the first partial optical path extending in the direction perpendicular to the optical axis of the objective lens, and the rest of the image-forming light beam of the objective lens. A first reflecting member for guiding a photographing optical path extending in a direction along the optical axis, and for guiding a light flux from the first reflecting member to a second partial optical path parallel to the first partial optical path and orthogonal to the optical axis of the objective lens. A second reflecting member having three reflecting surfaces, the second
A third reflecting member that guides the light flux from the reflecting member to a third partial optical path parallel to the optical axis of the objective lens, and a third guiding member that guides the light flux from the third reflecting member to the fourth partial optical path in which the eyepiece lens is arranged. 4 reflecting member, an image forming lens arranged in the first partial optical path between the first reflecting member and the second reflecting member and forming a first intermediate image which is smaller than a direct image by the objective lens. A relay lens disposed in the second partial optical path between the second reflecting member and the third reflecting member and forming a second intermediate image which is larger than the first intermediate image, At least one of the third reflecting member and the fourth reflecting member is configured to be rotatable by a predetermined angle about an axis perpendicular to a surface including the optical axis of the objective lens, and the relay lens is Negative lens and positive located across the optical axis Is composed of a lens, the first reflecting member, the second reflecting member, the third reflection member and the fourth reflecting member,
The objective lens is located on a plane including the optical axis.

〔Example〕

Examples of the present invention will be described below. In the embodiment according to the present invention, as shown in the optical configuration diagram in FIG. 1, the light flux reaching the image I of the object O formed by the objective lens 1 on the optical axis of the objective lens is used as the beam as the first reflecting member. First, the optical axis 1a of the objective lens 1 is moved by the splitter 2.
To form a first optical path extending in a direction perpendicular to the optical axis of the objective lens. The light beam from the first optical path is made to intersect the objective lens optical axis 1a at the upper part of the beam splitter 2 by the prism 4 as the second reflecting member having three reflecting surfaces, and the second optical path parallel to the first optical path is provided. To form.

As shown in the perspective view of FIG. 2, the prism 4 serving as the second reflecting member has a plane 4a parallel to the optical axis 1a of the objective lens and a first reflection having an inclination angle α with respect to the plane 4a. surface
It has 4b and the 2nd reflective surface 4c. Then, the light flux of the first optical path which is incident from the plane 4a parallel to the optical axis 1a is reflected by the first reflecting surface 4b, is totally reflected by the plane 4a parallel to the optical axis, and then is reflected by the second reflecting surface 4c. It is reflected and passes the plane 4a again,
It proceeds along the second optical path perpendicular to the objective lens optical axis 1a. That is, the prism 4 as the second reflecting member has a substantially isosceles triangular cross section, and its bottom surface functions as a total reflection surface as well as an entrance surface and an exit surface, and has an equal inclination angle. The two slopes 4a and 4b function as reflective surfaces. In reality, since the ridge line portion where the two slopes intersect is not necessary, the cross-sectional shape is cut out as shown in the perspective view of FIG. 2, so that the cross-section is configured as an isosceles trapezoidal prism.

The light flux traveling along the second optical path formed perpendicularly to the objective lens optical axis 1a by the prism 4 serving as the second reflecting member intersects the optical axis of the objective lens and then is reflected by the third reflecting member. The light is reflected by the mirror 6, is reflected along the third optical path parallel to the optical axis 1a of the objective lens, and is guided to the object O side.
The light flux from the third optical path is reflected by the movable mirror 7 serving as the fourth reflecting member, and is guided to the fourth optical path having the eyepiece lens 8 and the downward viewing angle θ.

All of the above-mentioned first to fourth reflecting members are located on a plane (paper surface of the figure) including the optical axis 1a of the objective lens 1, and the light flux from the object is reflected along this plane. It is configured to be.

In such an optical path configuration, the imaging lens 3 is arranged in the first optical path between the beam splitter 2 as the first reflecting member and the prism 4 as the second reflecting member, and the vicinity of the prism 4 is provided. Or an intermediate image I ₁ is formed therein. Then, in the second optical path between the prism 4 serving as the second reflecting member and the reflecting mirror 6 serving as the third reflecting member, the negative lens 5a and the positive lens arranged with the optical axis 1a of the objective lens 1 interposed therebetween. 5b and a relay lens 5 having an intermediate image I ₁ is formed as a secondary image I ₂ of the object near the front focal point of the eyepiece 8. Therefore, the intermediate image I ₁ formed by the objective lens 1 and the imaging lens 3 is an inverted image, but the secondary image I ₂ re-imaged by the relay lens 5 is an erect image. Then, from the first reflecting member to the fourth
Since it is a total of 6 reflections up to the reflection member,
The inversion of the image due to reflection does not occur, and the direction of the secondary image I ₂ becomes an erect image as determined by the lens system, and the object can be observed in the erect state through the eyepiece.

Here, in order to change the depression angle observed through the eyepiece lens 8, that is, the perspective angle θ of the fourth optical path having the eyepiece lens, as shown by the broken line in FIG. 1, the reflecting mirror 7 serving as the fourth reflecting member. Is configured so that its tilt angle can be changed by means (not shown) about an axis perpendicular to the surface (paper surface) including the optical axis 1a of the objective lens as a rotation center. At this time, it goes without saying that the amount of change in the tilt angle of the reflecting mirror 7 is one half of the amount of change in the depression angle θ. Further, if the inclination angle of the reflecting mirror 6 as the third reflecting member is also changeable and the direction of the third optical path parallel to the objective lens optical axis 1a can be changed, then the reflecting mirror 6 as the fourth reflecting mirror can be changed. By combining with the mirror 7, the depression angle can be changed, and the distance from the reflecting mirror 6 as the third reflecting member to the eyepiece lens 8 can be arbitrarily changed to change the position of the eyepiece lens with respect to the object to be inspected. It is also possible to change it appropriately according to the observation posture.

In the above configuration, the image forming lens 3 forms an intermediate image I ₁ as an intermediate image I ₁ which is smaller than the direct image I formed by the objective lens 1, and the reduced image is enlarged by the relay lens 5 at a predetermined magnification. It is desirable to form a secondary image I ₂ having a desired size by using the above method. For example, the image forming lens 3 reduces the intermediate image I ₁ by half, and the relay lens 2 reduces the intermediate image I _1.
It can be magnified twice, and as a result, a secondary image I ₂ having the same size as the direct image I obtained by the objective lens can be obtained. Further, as shown in the figure, the relay lens 5 is composed of the negative lens 5a and the positive lens 5b which are arranged with the optical axis 1a of the objective lens 1 interposed therebetween, so that the principal point of the relay lens is substantially the third reflection. By locating the member in the vicinity of the member 6, it is possible to increase the degree of freedom of arrangement of each member. Also negative lens
Due to the presence of 5a, Petzval sum as a relay lens can be corrected more favorably, and the flatness of the image plane can be favorably maintained.

In the above embodiment, the substantially isosceles triangular prism 4 is used as the second reflecting member having three reflecting surfaces, but the present invention is not limited to this. For example, the so-called penta prism 40a and reflecting prism 40b are used. The second reflecting member can also be constituted by and. In this case, the penta prism 40
The adjustment can be facilitated by the advantage that even if a is tilted on the surface (paper surface) perpendicular to the two reflecting surfaces, it does not affect the light rays emitted from this prism. However, there is a drawback that the second reflecting member is composed of two elements. In the prism 4 as the second reflecting member in the embodiment shown in FIG. 1, since the three reflecting surfaces are integrally formed, there is an advantage that the number of parts is reduced and therefore the supporting member is also reduced.

Further, in the above embodiment, the observation optical system from the first reflection member 2 to the fourth reflection member 7 and the eyepiece lens 8 is integrally supported by the observation lens barrel (not shown), and is attached to and detached from the objective lens 1. It is configured to be possible. Then, in the state in which this variable viewing angle lens barrel is mounted, it is possible to photograph an object image I by the light flux that passes through the beam splitter 2 as the first reflecting member by a television or a still camera.

〔The invention's effect〕

As described above, according to the present invention, all the optical paths except the final optical path in which the eyepiece lens is arranged are formed by the optical paths intersecting at a right angle. Therefore, it becomes easy to adjust the optical system, particularly the centering, and The structure and its processing become simple. Moreover, the six reflections necessary for observing an erect image can be accommodated in a small space, and the configuration of the entire viewing angle variable observation optical system can be reduced. In addition, since the optical paths do not intersect diagonally as in the conventional case, there are few restrictions on the arrangement of relay lenses and each reflecting member, and therefore the degree of freedom in design is high and the performance as an optical system can be improved. Further, since the effective diameter of each optical element can be increased, it is also advantageous in constructing an observation optical system having an ultra wide field of view.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of an embodiment according to the present invention,
FIG. 2 is a perspective view of a prism as a second reflecting member. Description of main parts of the code] 1 ...... objective lens, I ...... object image 2 ...... first reflecting member, I ₁ ...... intermediate image 3 ...... imaging lens, I ₂ ...... secondary image 4 ...... Second reflecting member 5 ... Relay lens 6 ... Third reflecting member 7 ... Fourth reflecting member 8 ... Eyepiece lens

Claims (2)

[Claims] 1. A part of an image-forming light beam from an objective lens is guided to a first partial optical path extending in a direction perpendicular to the optical axis of the objective lens, and the rest of the image-forming light beam is directed to the optical axis of the objective lens. A first reflecting member for guiding to a photographing optical path extending in a direction along the first reflecting member;
A second reflecting member having three reflecting surfaces for guiding the light flux from the reflecting member to a second partial light path that is parallel to the first partial light path and is orthogonal to the optical axis of the objective lens, and the light flux from the second reflecting member. A third reflecting member that guides the light to a third partial optical path parallel to the optical axis of the objective lens, a fourth reflecting member that guides the light flux from the third reflecting member to a fourth partial optical path in which an eyepiece lens is arranged, An imaging lens disposed in the first partial optical path between the first reflection member and the second reflection member and forming a first intermediate image that is smaller than the direct image by the objective lens, the second reflection A relay lens disposed in the second partial optical path between the member and the third reflecting member, the relay lens forming a second intermediate image that is larger than the first intermediate image; At least one of the fourth reflecting member is the light of the objective lens. It is configured to be rotatable by a predetermined angle about an axis perpendicular to a plane including an axis, the relay lens is composed of a negative lens and a positive lens arranged with an optical axis of the objective lens interposed therebetween, The 1st reflecting member, the 2nd reflecting member, the 3rd reflecting member, and the 4th reflecting member are located on the surface containing the optical axis of the said objective lens, The downward viewing angle variable observation optical system characterized by the above-mentioned. 2. The second reflecting member includes a flat surface 4a parallel to the optical axis 1a of the objective lens, a first reflecting surface 4b and a second reflecting surface 4c having the same inclination angle with respect to the flat surface 4a. The variable viewing angle observation optical system according to claim 1, wherein the observation optical system is a prism having a.