Optical: systems and elements – Lens – With support
Reexamination Certificate
2002-07-09
2004-03-09
Mack, Ricky (Department: 2873)
Optical: systems and elements
Lens
With support
Reexamination Certificate
active
06704151
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-209320, filed Jul. 10, 2001; and No. 2001-209321, filed Jul. 10, 2001, the entire contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical unit including a high-precision objective unit having a lens, a lens frame, and a lens barrel and a method of assembling the optical unit.
Further, the present invention relates to an optical unit having a lens-holding apparatus suitable for a high-precision objective lens, etc.
2. Description of the Related Art
Conventionally, as shown in
FIG. 7
, a microscope objective unit includes a plurality of lenses
103
a
through
103
f
, a plurality of lens frames
102
a
through
102
d
for holding the lenses
103
a
through
103
f
, and a lens barrel
101
.
The lens frames
102
a
through
102
d
have substantially the same outside diameter. The lens frames
102
a
through
102
d
hold lenses
103
a
through
103
f
. The lens frames
102
a
through
102
d
have center axes for the outside diameters. The center axes of the lens frames
102
a
through
102
d
substantially correspond to optical axes of the lenses
103
a
through
103
f.
The lens barrel
101
has the center axis. The lens barrel
101
is cylindrical and has a hole
101
a
along the center axis. The hole
101
a
has an inside diameter substantially the same as the outside diameter of the lens frames
102
a
through
102
d.
The lens frames
102
a
through
102
d
holding the lenses
103
a
through
103
f
are inserted into the hole
101
a
. The center axes of the lens frames substantially correspond to the center axis of the lens barrel
101
. Consequently, optical axes of the lenses
103
a
through
103
f
substantially correspond to each other in the hole
101
a.
The objective unit is assembled by inserting the lens frames holding the lenses into the lens barrel. This assembling method can provide centering more accurately than a method of assembling the objective unit by directly dropping the sets of lenses
103
a
through
103
f
into the lens barrel
101
.
There is provided a plurality of types of lens frames as means for holding lenses. For example, the holding means is available as a lens frame as shown in FIG.
8
.
FIG. 8
shows an optical unit including the above-mentioned lens frame. The optical unit has a set of lenses including lenses
103
g
and
103
h
. In the set of lenses, optical axes of the lenses
103
g
and
103
h
are coaxially arranged. In
FIG. 8
, the reference numeral
105
represents an optical axis of the set of lenses.
A lens frame
102
e
has a predetermined outside diameter. The lens frame
102
e
has a center axis for the outside diameter. The lens frame
102
e
has a lens frame edge
104
orthogonal to the center axis. The lens frame edge
104
is formed with high precision along a direction orthogonal to the center axis. The lens frame
102
e
has a stop which extends toward the inside of the frame itself along a direction orthogonal to the center axis. The stop has a retaining surface for seating a lens.
When the lens frame
102
e
is used to hold lenses, a set of lenses (cemented lens) including the lenses
103
g
and
103
h
is dropped onto the retaining surface in the lens frame
102
e
. The set of lenses is held on the retaining surface of the lens frame
102
e
. The set of lenses is fixed to the retaining surface with adhesive.
When adhesively bonding the above-mentioned lens set to the lens frame
102
e
, the lens
103
h
is first placed on the retaining surface. The lens frame
102
e
is then moved along the lens frame edge
104
. More specifically, the lens frame
102
e
rotates around its center axis on the lens frame edge
104
. The lens
103
h
is centered with respect to the lens frame
102
e
by the rotating. The lens frame
103
h
is then adhesively bonded to the lens frame
102
e
. Likewise, the lens
103
g
is arranged on the lens
103
h
and is centered with respect to the lens frame
102
e
. The lens
103
g
is then adhesively bonded to the lens
103
h
. The lens frame
102
e
having the retaining surface is often used as a lens holding means for ordinary objective units.
FIG. 9
shows a lens frame
102
f
as another example of the above-mentioned holding means. The lens frame
102
f
in
FIG. 9
is configured to be capable of plastic deformation. The lens frame
102
f
is configured to include a lens
103
i
. The lens frame
102
f
is caulked at its end to fix the lens
103
i
. Accordingly, the lens frame
102
f
can fix the lens
103
i
without using adhesive. The means for caulking the lens frame
102
f
has been long used.
FIG. 10
shows a holding means capable of maintaining a clearance along optical axes of two lenses.
FIG. 10
also shows an optical unit including the above-mentioned holding means. The optical unit has a set of lenses A comprising a convex lens
31
and a concave lens
32
bonded to each other and a set of lenses B comprising a convex lens
33
and a concave lens
34
bonded to each other.
The holding means in
FIG. 10
has a lens frame
144
for holding the set of lenses A and a lens frame
146
for holding the set of lenses B. The holding means further has a clearance ring
145
arranged between the lens frames
144
and
146
. The clearance ring separates the lens frames
144
and
146
with a predetermined clearance along center axes of the lens frames
144
and
146
. Consequently, the sets of lenses A and B can separate predetermined clearance along the optical axes thereof.
The set of lenses in
FIG. 8
including the lenses
103
g
and
103
h
is dropped into the lens frame
102
e
to be seated in the lens frame
102
e
. Accordingly, the lens frame
102
e
can be bonded while the set of lenses is centered. The lens frame
102
e
needs to have a stop because the set of lenses is dropped thereinto. The space for providing the stop is needed around the lens frame
102
e.
As shown in
FIG. 11
, however, there is no space around the lens frame
102
e
for an optical system in which lenses are arranged close to each other. It is difficult for the lens frame
102
e
to maintain or bond the optical system in FIG.
11
.
The lens frame
102
f
in
FIG. 9
holds the lens
103
i
by caulking as mentioned above. Generally, the lens frame
103
f
is caulked at a very small portion thereof. Thus this caulking is difficult. When the lens
103
i
is fixed by caulking, the accuracy of centering depends on the worker's experience and skill. When optical unit are manufactured through the use of caulking, there is a problem of widely varying the quality of the optical unit.
As mentioned above, the holding means in
FIG. 10
has a clearance ring
145
in addition to the lens frames
144
and
146
. Since the holding means has a plurality of members, the structure is complicated. Accordingly, it is difficult to improve the accuracy of centering for the set of lenses A and B. Since the holding means has the complicated structure, a clearance between the set of lenses may not be provided highly precisely.
As shown in
FIG. 12
, there is devised a holding means having a simplified structure. The simplified structure is provided by integrating the lens frame
144
and the clearance ring
145
in FIG.
10
. In
FIG. 12
, the reference numeral
148
represents a lens frame formed by integrating the lens frame
144
and the clearance ring
145
. The use of the lens frame
148
simplifies the optical unit configuration. However, the lens frame
148
has a larger dimension in the direction along its center axis than that of the lens frame
144
. Accordingly, the set of lenses A is arranged at an inner part in the direction along the center axis of the lens frame
148
. The lens frame
148
makes it difficult to center the set of lenses A.
Especially, a microscope objective unit using wavelengths in an ultraviolet range uses more lenses than a microscope objective
Nishimura Osamu
Yamashita Hideto
Frishauf Holtz Goodman & Chick P.C.
Mack Ricky
Olympus Optical Co,. Ltd.
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