Optical: systems and elements – Compound lens system – Microscope
Reexamination Certificate
2001-03-13
2002-06-18
Henry, Jon (Department: 2872)
Optical: systems and elements
Compound lens system
Microscope
C359S368000, C359S431000
Reexamination Certificate
active
06407857
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a lens barrel with variable eyepoint position and a microscope using the same lens barrel. Hereafter, this type of lens barrel will be simply referred to as “variable lens barrel”.
2) Description of Related Art
Various proposals have been made for a lens barrel used in microscopy regarding adjustment of the position at which the ocular is looked into (i. e. eyepoint) so as to allow an observer to easily perform observation in relaxed posture.
For example, Japanese Patent Application Preliminary Publication (KOKAI) No. Hei 4-166907 proposes a tilting lens barrel which is provided with a mechanism for adjusting the depression angle, or the angle in which an observer looks into the ocular of the binocular section. This configuration is intended to adjust the height and position of the eyepoint by changing the depression angle.
Also, Japanese Patent Application Preliminary Publication (KOKAI) No. Hei 8-278448 proposes to lower the eyepoint position by deflecting a beam of rays emergent from the objective using a deflecting member. The object of this proposal is to allow an observer to perform observation in relaxed posture by preliminarily lowering the eyepoint position.
Also, Japanese Patent Application Preliminary Publication (KOKAI) No. Hei 10-142473 proposes a lens barrel that is provided with a tilting mechanism for changing the depression angle and a mechanism for moving it along the observation optical axis. The object of this proposal is to change each of the height of the eyepoint position and the horizontal distance from the optical axis of the objective to the position of the eye of an observer.
Also, Japanese Patent Application Preliminary Publication (KOKAI) No. Hei 9-73031 discloses a microscope comprising an optical system that is made afocal between an objective and an imaging lens, which is housed in a movable lens barrel. The afocal beam between the objective and the imaging lens is deflected in the horizontal direction by a first deflecting member and is further deflected by 90° by a second reflecting member, to enter the imaging lens. A guide is provided between the first deflecting member and the second reflecting member so that the second deflecting member and the movable lens barrel are integrally moved for changing the eyepoint position.
In microscopy, especially in the case where inspection of a large number of specimens or samples takes a long time, it is very important, for preventing fatigue of an observer/inspector and inaccurate inspection result caused by carelessness, to allow the observer to work in a relaxed posture.
FIG. 22
shows the outer dimensions of an ordinary microscope. In order to relieve fatigue of each observer in the case where tall and large-built individuals and short and small-built individuals have to use a common microscope, it is important that values of 1) the height H from a desk top surface
2
to an eyepoint position E of an ocular OC, 2) the angle (depression angle) &thgr; at which the observer looks into the ocular OC, and 3) the horizontal distance d from the optical axis of an objective OB to the eyepoint position E of the ocular are appropriately set for each observer. In order to allow an observer of whatever build to perform long-time observation in a natural posture, the eyepoint position E of the ocular OC is required to be at the eyes of the observer under the condition where the observer puts the hand on a focusing wheel
3
in a natural posture. Regarding an ordinary microscope, the height of the specimen surface
1
from the desk top surface
2
is 200 mm, and the height of a lens barrel 4-side mount position
8
of a microscope body
5
is 305 mm from the desk top surface
2
. In
FIG. 22
, the reference numeral
6
and the reference numeral
7
represent a condenser lens and a stage control, respectively.
If a titling lens barrel proposed by Japanese Utility Model Application Preliminary Publication (UM-KOKAI) No. 4-124218 is combined with this microscope, the minimum height of the eyepoint position E from the desk top surface
2
is approximately 400 mm. Also, since the tilting lens barrel can change the depression angle &thgr;, the height from the desk top surface
2
is variable approximately in a range from 400 mm to 500 mm. Also, the distance from the optical axis of the objective OB to the center position of the focusing wheel
3
is approximately 100 mm. In the case of an ordinary lens barrel, the eyepoint position E is distant from the optical axis of the objective OB approximately by 195 mm. In the case of a tilting lens barrel, which can change the depression angle &thgr;, the horizontal distance is variable approximately in a range from 140 mm to 195 mm.
If the depression angle &thgr; is changed using the above-mentioned tilting lens barrel, which simply changes the depression angle, the horizontal distance from the optical axis of the objective OB to the eyepoint position E is changed only by a small amount. However, the horizontal distance becomes shorter as the angle in reference to a horizontal plane is larger. This correlation makes it impossible to allow any observer of whatever build to perform observation in a natural posture. A tall and large-built person requires a longer horizontal distance from the optical axis of the objective and, as a matter of course, a higher eyepoint position than a short and small-built person does. For example, the optimum height of the eyepoint from the desk top surface
2
for a person of 1580 mm height is approximately 430 mm, whereas, for a person of 1840 mm height, the lowest necessary height of the eyepoint is approximately 510 mm from the desk top surface
2
and the optimum height of the eyepoint is approximately 600 mm from the desk top surface
2
on condition that the height of the desk top surface
2
from the floor is 70 cm and the height of a chair used during observation is appropriately adjusted. Therefore, even if the eyepoint height is adjusted to the maximum height using the conventional lens barrel
4
, the person of 1840 mm height is obliged to keep an unnatural posture. In addition, the horizontal distance from the optical axis of the objective to the eyepoint also is too short, and, as a result, the posture of the observer looks as if he hunches over and hugs the microscope, to increase fatigue during observation, which is a problem. Also, even if an intermediate lens barrel is combined with the tilting lens barrel for adjustment of the eyepoint height, the eyepoint is allowed to be raised approximately by 60 mm at most, in effect. If the eyepoint is set higher than this limit, eclipse or short amount of marginal rays affects the image. As discussed above, use of the tilting lens barrel obliges a tall and large-built person to take an unnatural posture.
According to the lens barrel proposed by KOKAI No. Hei 10-142473, the depression angle and the eyepoint position are made variable independent of each other. However, in the lens arrangement of KOKAI No. Hei 10-142473, since a beam of rays from the objective is designed to be relayed to the focal plane of the ocular without imaging, a sufficiently long path length cannot be secured in the lens barrel. Therefore, it is substantially impossible to secure a sufficiently long horizontal distance from the objective to the eyepoint while providing a wide variable range of the eyepoint height for the above-mentioned adaptation of the microscope to variously built observers.
Also, within the scope of this conventional proposal, if the movable distance in the afocal section is designed to be long so as to allow the eyepoint position to be largely spaced away, the effective diameter through lenses and a binocular prism section becomes larger with degraded aberration performance by off-axial rays and the exit pupil position is largely displaced, to cause eclipse at the ocular.
Alternatively, if a design is made so that the afocal magnification of the first optical system and the second optical system is large and t
Henry Jon
Olympus Optical Co,. Ltd.
Pillsbury & Winthrop LLP
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