JPS61294408A - Depression visual angle variable observation optical system - Google Patents

Abstract

PURPOSE:To vary the depression visual angle of the titled system with easy working and adjustment and with a small size by consisting the lens of the 1st-4th reflection members, imaging lens and relay lens and constituting either of the 3rd and 4th reflection members in such a manner that the member can rotate at a prescribed angle around the axis perpendicular to the plane inclusive of the optical axis of an objective lens. CONSTITUTION:This lens has the 1st reflection member 2 which directs the imaging luminous flux in the direction perpendicular to the optical axis of the objective lens, the 2nd reflection members 4 having the three reflection faces which conduct the luminous flux from the 1st branching path in the direction parallel with the 1st branching path and orthogonal with the optical axis of the objective lens and the 3rd reflection member 6 which conducts the luminous flux from the 2nd reflection member in the direction parallel with the optical axis of the objective lens. The lens has the 4th reflection member 7 which conducts the luminous flux from the 3rd reflection member to the 4th branching path, the imaging lens 3 which is disposed between the 1st reflection member and the 2nd reflection member and forms an intermediate image by converging the luminous flux from the objective lens and the relay lens 5 disposed between the 2nd reflection member and the 3rd reflection member. The lens is so constituted that either of the 3rd reflection member and the 4th reflection member can rotate by the prescribed around the axis perpendicular to the plane inclusive of the optical axis of the objective lens. The depression visual angle is thereby made variable and the constitution in made small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an observation lens barrel of a microscope, and particularly to an observation optical system that can change the viewing angle.

[Background of the invention]

Conventionally, various observation barrels for microscopes that can adjust the viewing angle for observation have been known, for example, U.S. Pat. No. 4.29
9.439 and JP-A-59-159119 are known. In these configurations, the optical path for guiding the light flux from the objective lens to the eyepiece is bent in various directions and is not at right angles but at an angle, which imposes restrictions on the combination of optical elements such as relay lenses and prisms. (, the arrangement of each element and optical path length are limited,
It was difficult to create a compact configuration. Furthermore, since the optical path is not perpendicular, it is difficult to adjust the optical axis, which increases the difficulty in manufacturing and processing the lens barrel.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an observation optical system that is easy to process and adjust, has a compact configuration, and has a variable viewing angle.

[Summary of the invention]

The observation optical system according to the present invention includes a first reflecting member that guides an imaging light beam from an objective lens to a first partial optical path extending in a direction perpendicular to the optical axis of the objective lens; a second part having three reflective surfaces for guiding it to a second part optical path parallel to the first part optical path and perpendicular to the optical axis of the objective lens;
a reflective member, a third reflective member that guides the light flux from the second reflective member to a third partial optical path parallel to the optical axis of the objective lens, and a third reflective member that directs the light flux from the third reflective member to a third partial optical path parallel to the optical axis of the objective lens; a fourth reflective member that guides the four partial optical paths, and is disposed in the first partial optical path between the first reflective member and the second reflective member to converge the light beam from the objective lens to form an intermediate image of the object. an imaging lens, a relay lens disposed in the second partial optical path between the second reflective member and the third reflective member, and at least one of the third reflective member and the fourth reflective member; is configured to be rotatable by a predetermined angle about an axis perpendicular to a plane containing the optical axis of the objective lens. By arranging the first, second, third, and fourth reflecting members on a plane that includes the optical axis of the objective lens, it is possible to have the smallest optical system configuration.

〔Example〕

Embodiments of the present invention will be described below. In the embodiments of the present invention, an image of an object ○ formed by an objective lens l on the optical axis of the objective lens, as shown in the optical configuration diagram shown in FIG. A beam splitter 2 serving as a first reflecting member directs the light beam reaching I to the optical axis 1 of the objective lens 1.
a, forming a first optical path extending in a direction perpendicular to the optical axis of the objective lens. The light beam from this first optical path is made to intersect with the objective lens optical axis 1a at the upper part of the beam splitter 2 by a prism 4 as a second reflecting member having three reflecting surfaces. Forms a light path.

As shown in the perspective view of FIG. 2, the prism 4 as a second reflecting member has a plane 4a parallel to the optical axis 1a of the objective lens, and a first prism 4 having an equal inclination angle α with respect to the plane 4a.
It has a reflective surface 4b and a second reflective surface 4c. The light beam in the first optical path entering from the plane 4a parallel to the optical axis 1a is reflected by the first reflecting surface 4b, and
After being totally reflected at a, it is reflected at the second reflecting surface 4c,
The light passes through the plane 4a again and proceeds along a 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 serves as an incident surface and an exit surface as well as a total reflection surface.
Two slopes 4a with equal inclination angles.

4b each functions as a reflecting surface. In practice,
Since the ridgeline 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 formed as a prism with an isosceles trapezoid.

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

The first to fourth reflecting members described above are all located on a plane (the plane of the drawing) that includes the optical axis 1a of the objective lens 1, and the light flux from the object is reflected along this plane. The configuration is as follows.

In such an optical path configuration, the imaging lens 3 is disposed 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 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. forming an intermediate image I, near or within it; Then, the prism 4 as the second reflecting member and the third
A negative lens 5a disposed on both sides of the optical axis 1a of the objective lens 1 is disposed in the second optical path between the reflection mirror 6 as a reflection member.
A relay lens 5 having a positive lens 5b and a positive lens 5b is disposed, whereby an intermediate lens 5 is formed as a secondary image 12 of an object near the front focal position of the eyepiece 8.

Therefore, the intermediate image X1 formed by the objective lens 1 and the imaging lens 3 is an inverted image, but the secondary image I, which is re-imaged by the relay lens 5, is an erect image. and,
Since there is an even number of reflections, 6 times in total, from the first reflecting member to the fourth reflecting member, there is no inversion of the image due to reflection, and the direction of the secondary image 2 is determined by the lens system. The image becomes erect, and the object can be observed in an upright position through the eyepiece.

Here, in order to change the viewing angle observed through the eyepiece 8, that is, the inclination angle θ of the fourth optical path having the eyepiece, as shown by the broken line in FIG. is configured such that its inclination angle can be changed by a means (not shown) around an axis perpendicular to the plane (plane of the paper) containing the optical axis la of the objective lens as the center of rotation.At this time, the amount of change in the inclination angle of the reflecting mirror 7 is Needless to say, this is -half of the required change in the viewing angle θ.Furthermore, the reflecting mirror 6 as the third reflecting member is also configured so that its inclination angle can be changed, so that the angle of inclination of the reflecting mirror 6 is changeable. If the direction of the parallel third optical path can be changed, the viewing angle can be changed by combining it with the reflector 7 as the fourth reflector, and the direction from the reflector 6 as the third reflector to the eyepiece can be changed. By arbitrarily changing the distance up to 8, it is also possible to change the position of the eyepiece relative to the object to be examined as appropriate depending on the observation posture of the observer.

In the above configuration, the imaging song 3 forms an object image as an intermediate image II which is smaller than the direct image I formed by the objective lens 1, and this reduced image is enlarged by a predetermined magnification by the relay lens 5. Secondary image I2 of desired size
For example, it is desirable to form an intermediate image (■) by the imaging lens 3 by 2 minutes (7) 1 mm, and then magnify it by a factor of 2 by the relay lens, so that the result is equal to the direct image (■) by the objective lens. It can be a secondary image of size 2. Further, as shown in the figure, by configuring the relay lens 5 with a negative lens 5a and a positive lens 5b disposed on both sides of the optical axis 1a of the objective lens 1, the principal point of the relay lens can be substantially converted into a third reflection. By locating it near the member 6, it is possible to increase the degree of freedom in the arrangement of each member. Moreover, the presence of the negative lens 5a allows the Petzval sum as a relay lens to be corrected even better, and it is possible to maintain the flatness of the image plane well.

In the above embodiment, a substantially isosceles triangular prism 4 is used as the second reflecting member having three reflecting surfaces, but the prism 4 is not limited to this, and for example, a so-called pentaprism 40a and a reflecting prism 40b are used. It is also possible to configure the second reflecting member with the above. In this case, Ventab 1
Even if the prism 40a is disposed at an angle in a plane (plane of paper) perpendicular to its both incident planes, the adjustment can be made easy due to the advantage that it does not affect the light rays exiting this prism. However, there is also the drawback that the second reflective member is composed of two elements. In the prism 4 as the second reflecting member in the embodiment shown in FIG.
Since the two reflective surfaces are integrally constructed, there is an advantage that the number of parts is reduced, and therefore the number of supporting members thereof is also reduced.

In addition, in the above embodiment, the observation optical system including the first reflection unit) second to fourth reflection members 7 and the eyepiece lens 8 is integrally supported by an observation lens barrel (not shown), and is connected to the objective lens 1. It is configured to be detachable. In a state in which the variable viewing angle lens barrel is attached, it is possible to project an object image I formed by a beam of light passing through the beam splinter 2 serving as the first reflecting member using a television or a still camera.

〔Effect of the invention〕

As described above, according to the present invention, all the optical paths except the final optical path where the eyepiece is arranged are composed of optical paths that intersect at right angles, so that it is easy to adjust the configuration of the optical system, especially the centering adjustment, and to adjust the alignment of the lens barrel. The structure and processing become simple. Furthermore, the six reflections required to observe an erect image can be contained within a small space, making it possible to downsize the entire configuration of the viewing angle variable viewing optical system. In addition, unlike in the past (because the optical paths do not intersect diagonally, there are fewer restrictions on the placement of the relay lens and each reflective member, and therefore there is a high degree of freedom in design and it is possible to improve the performance of the optical system. Furthermore, since it is possible to increase the vector radius of each optical element, it is advantageous for constructing an ultra-wide-field observation optical system.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the configuration of an embodiment according to the present invention;
FIG. 2 is a perspective view of a prism as a second reflecting member. [Explanation of symbols of main parts] 1... Enclosure lens ■... Object image 2...
First reflecting member 11... Intermediate image 3... Imaging lens I2... Secondary image 4... Second reflecting member 5... Relay lens 6... Third reflecting member 7... Fourth reflective member 8...eyepiece

Claims (1)

[Scope of Claims] 1) A first reflecting member that guides the imaging light beam from the objective lens to a first partial optical path extending in a direction perpendicular to the optical axis of the objective lens; a second reflective member having three reflective surfaces for guiding the light beam from the second reflective member to a second partial optical path that is parallel to the first partial optical path and perpendicular to the optical axis of the objective lens; a third reflecting member that guides the light flux from the third reflecting member to a third partial optical path parallel to the third reflecting member; a fourth reflecting member that guides the luminous flux from the third reflecting member to a fourth partial optical path in which an eyepiece is disposed; an imaging lens disposed in a first partial optical path between the reflecting member and a relay lens disposed in the second partial optical path between the second reflecting member and the third reflecting member; 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 plane including the optical axis of the objective lens. Variable observation optical system. 2) The first reflecting member, the second reflecting member, the third reflecting member, and the fourth reflecting member are located on a plane including the optical axis of the objective lens. Observation optical system with variable overhead viewing angle as described in . 3) The second reflecting member has a plane 4a parallel to the optical axis 1a of the objective lens, and a first reflecting surface 4b and a second reflecting surface 4c having equal inclination angles with respect to the plane 4a. Claim 2, characterized in that it is a prism.
Observation optical system with variable overhead viewing angle as described in .