Optical waveguides – With optical coupler – With alignment device
Reexamination Certificate
2002-02-26
2004-10-05
Ullah, Akm Enayet (Department: 2874)
Optical waveguides
With optical coupler
With alignment device
C385S028000, C385S062000, C385S070000, C385S090000
Reexamination Certificate
active
06801694
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and a method for face alignment. More particularly, the present invention relates to a device and a method for face alignment used for adjusting faces and center axes of optical components upon bonding the optical components.
BACKGROUND OF THE INVENTION
In order to adjust faces and center axes of optical components upon bonding them, a face tracing/center axes aligning mechanism as shown in
FIG. 6
is conventionally employed.
This mechanism is provided with a stacked adjustment stage unit which is attached with a clamp member
121
. The clamp member
121
clamps one object
120
. The stage unit includes a height adjustment stage
122
, a transversal adjustment stage
123
and a longitudinal adjustment stage
124
. The mechanism is further provided with a height adjustment stage
114
, a transversal adjustment stage
115
, a longitudinal adjustment stage
116
, a longitudinal flap stage
117
, a transversal flap stage
125
and a clamp member
118
for clamping the other object
119
.
In the above-described structure, the objects
119
and
120
are set and clamped by the clamp members
118
and
121
, respectively. Here, the center axes of the objects
119
and
120
are matched by adjusting each of the stages as confirmed by the outer appearance or optical transfer characteristic of the objects.
Then, after the object
120
is lowered by the height adjustment stage
122
and the state of face contact between the objects
119
and
120
is confirmed, face alignment takes place. Specifically, after confirming face contact between the objects
119
and
120
, the objects are once separated from each other to adjust the transversal flap stage
125
and the longitudinal flap stage
117
so as to find positions where the faces of the objects are parallel to each other. At this point, positions of the center axes of the objects
119
and
120
are once again confirmed. In most cases, the center axes are offset from each other at this point, and thus the above-described adjustment is repeated for several times to align the center axes and the faces of the objects
119
and
120
.
Another example of a conventional face alignment device is disclosed, for example, in Japanese Patent Laid-Open Application No. 8-281464, which is shown in FIG.
7
.
This face alignment device is provided with a clamp member
107
for securing one object
108
on a seat
106
which has a convex spherical surface on one side. In this device, the other object
109
is lowered perpendicularly onto the object
108
so as to allow contact between the faces of the objects. Specifically, in order to allow contact between the faces of the objects, the seat
106
having the convex spherical surface is slidably accommodated in a seat support member
103
which has a concave spherical surface formed in a base block
101
. An air compressor pump
113
sends air via a switch valve
112
, an air guiding path
111
, an air receiver
102
and air throughholes
104
that are formed through the seat support member
103
, thereby forming an air layer
105
.
The air layer
105
formed as described above will cause the seat
106
having the convex spherical surface to float, thereby eliminating sliding resistance between the seat
106
and the seat support member
103
. Then, the object
109
is lowered perpendicularly onto the object
108
so that faces of both objects make contact with each other. At this point, the seat
106
having the convex spherical surface freely slides so that the face of the object
108
traces the tilt of the contacting face of the object
109
.
Accordingly, the faces of the objects
108
and
109
can be aligned by applying pressure to each other. Thereafter, the injected air is evacuated by a vacuum pump
114
via the switch valve
112
, whereby the seat
106
is suctioned and makes contact with the seat support member
103
. Since no pressure applying mechanism such as the above-mentioned air compressor pump is placed near the contact faces of the objects on the seat
106
, laser light sources
110
can be provided at any positions substantially horizontal to the objects, thereby enabling to weld the objects
108
and
109
together.
As a third conventional example, Japanese Patent Laid-Open Application No. 7-63961 discloses a method for assembling an optical semiconductor module. This method uses a jig having first and second blocks. The first block has an upper surface with a setting hole for holding a lens holder member having an optical semiconductor device, and a convex semi-spherical bottom surface. The second block has a concave semi-spherical surface corresponding to the convex semi-spherical surface of the first block so as to rotatably hold the first block. This jig secures an optical fiber and the lens holder member held in the setting hole of the first block while they are making contact. Thus, the center axes of the lens holder and the optical fiber can easily be adjusted upon assembly, while their faces are maintained to be parallel to each other, thereby enhancing optical accuracy.
However, in the face tracing/center axes adjusting mechanism according to the first conventional example, each object is adjusted by the mechanism of triaxial or pentaxial stages. As a result, the size of a control system becomes considerably large as compared to the size of the product, and a large area of the work area will be occupied by the device. In addition, since there are many axes involved that need to be controlled, operation of the device takes a long period of time, thereby deteriorating the working efficiency.
In the face alignment device and the method for assembling an optical semiconductor module according to the second and third conventional examples, respectively, the objects are placed on a flat surface opposite to the convex spherical surface, in the vicinity of the center axis of the convex spherical surface. Accordingly, external force is mostly applied downward, and thus force for letting the face of the object to trace the tilt of the other face (i.e., force for promoting rotation along the spherical surface) becomes small. Thus, in order to promote rotation of the spherical surface with the load applied to the center axis of the upper surface to let one face trace the other, a considerably large force is required, which may result in breaking or damaging the objects.
As another problem caused in the second and third conventional examples, objects are not placed at a position corresponding to the center of the spherical surface, which may result in offset of center axes of the objects from each other. If the objects are placed at a position corresponding to the center of the spherical surface, the faces can trace each other without changing the center axes of the objects and using the center axis as a base point. However, in the conventional examples, objects are not placed at a position corresponding to the center of the spherical surface and thus the center axes of the objects are offset from each other. As a result, the center axis needs to be readjusted after face tracing.
In more detail, as a general procedure, faces of the objects are allowed to make contact with each other such that there is no space between them, and then, the center axes of the objects are aligned. However, face tracing followed by alignment of the center axes of the objects needs to be carried out for several times while confirming the appearance or the optical transfer characteristic of the objects, thus requiring a long period of time.
In the face alignment device of the second conventional example, in order to eliminate sliding resistance between the seat support member and the seat clamping the object, the convex spherical surface of the seat is floated by forming a layer with air injected through the air throughholes in the concave spherical seat support member. The thickness of the air layer formed between the seat and the seat support member is several &mgr;m.
In the following step, face of one object is allowed to trace the face of
Foley & Lardner LLP
NEC Engineering Ltd.
Rahll Jerry T
Ullah Akm Enayet
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