Geometrical instruments – Straight-line light ray type – Level
Reexamination Certificate
1998-08-26
2001-07-03
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Straight-line light ray type
Level
C033S281000, C033S282000, C033S285000, C033S286000, C033SDIG002, C356S138000, C359S364000, C359S423000
Reexamination Certificate
active
06253457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a laser beam direction correcting optical system for a surveying instrument which emits a laser beam in a specific direction.
2. Description of the Related Art
Some of the surveying instruments have a rotating laser emitting device which rotates laser light within a horizontal plane to generate a reference plane.
FIG. 9
shows an example of the rotating laser emitting device. This rotating laser emitting device is equipped with a visible semiconductor laser
1
as a laser light source, a collimator lens, an incident angle correcting means
3
, and a laser rotating-scanning means
4
.
The visible semiconductor laser
1
is driven by a pulse drive circuit
5
consisting of an oscillator
5
a
and an LD drive circuit
5
b.
The collimator lens
2
converts the laser light emitted from the visible semiconductor laser
1
to a collimated light beam P
1
. The collimated light beam P
1
is incident upon the incident angle correcting means
3
.
The laser rotating-scanning means
4
is equipped with a vertical-direction orienting means
6
and a pentagonal prism
7
which reflects the laser light incident upon the orienting means
6
in a horizontal direction. The pentagonal prism
7
is mounted on a rotary mounting table
8
so that it can rotate. With rotation of this pentagonal prism
7
, the laser light is rotated within a horizontal plane and emitted to an irradiated object.
The incident angle correcting means
3
is equipped with an in-X plane inclination correcting means and an in-Y plane inclination correcting means perpendicular to the in-X plane inclination correcting means. The in-X plane inclination correcting means is constituted by an oil bath
10
, enclosed glasses
11
and
12
, and oil
13
enclosed within the oil bath
10
. The in-Y plane inclination correcting means is constituted by a pair of prisms
14
and
15
. The oil
13
is horizontally maintained regardless of an inclination of the instrument main body. The direction of reflection of the collimated light beam P
1
within an X plan is corrected according to an inclination of the instrument main body by the back surface
13
a
of the oil
13
, and the corrected light beam P
1
is guided to the in-Y plane inclination correcting means. The inclination of the guided light beam P
1
within a Y plane is corrected by the in-Y plane inclination correcting means, and the corrected light beam P
1
is guided to the vertical-direction orienting means
6
. The incident angle correcting means
3
is interposed between the visible semiconductor laser
1
and the vertical-direction orienting means
6
. The incident angle correcting means
3
fulfills a role of correcting an incident angle of the collimated light beam P
1
incident upon the vertical-direction orienting means
6
in accordance with an inclination of the instrument main body.
The vertical-direction orienting means
6
consists of a reflecting mirror
16
and an exit angle correcting means
17
. The exit angle correcting means
17
consists of a first objective lens
18
and a second objective lens
19
. This exit angle correcting means
17
fulfills a role of correcting an exit angle of the laser light beam emerging from the second objective lens
19
in accordance with an inclination of the instrument main body so that the laser light beam is oriented in a specific direction (e.g., a vertical direction).
Incidentally, in surveying instruments, a distance to an irradiated object is not constant, and in order to make emission efficiency variable in accordance with each distance, there have been demands that a function of focusing laser light on an irradiated object be added to the exit angle correcting means
17
. More specifically, there have been demands that laser light be emitted to an irradiated object not as a collimated light beam but as an image forming light beam.
Particularly, in the case of visible laser light, if laser light is emitted as a collimated light beam, the laser light will become more difficult to see as distance increases. For this reason, it is desirable that the image of laser light be formed in an irradiated object.
In the conventional rotating laser light emitting device, however, laser light is incident upon the exit angle correcting means
17
after it has been corrected by the incident angle correcting means
3
. For this reason, if the first objective lens
18
of the exit angle correcting means
17
is moved in the optical axis O of the correcting means
17
so that laser light is focused on an irradiated object, then the laser light emerging from the second objective lens
19
will be shifted from a specific direction. Therefore, the problem of degrading correction accuracy in the exit angle of an outgoing light beam arises for the following reasons.
As shown in FIG.
10
(
a
), the incident angle of a collimated light beam incident upon the first objective lens
18
relative to the optical axis O of the exit angle correcting means
17
is taken to be &thgr;
in
. Also, the exit angle of the collimated light beam P
1
emerging from the second objective lens
19
relative to the optical axis O of the exit angle correcting means
17
is taken to be &thgr;
out
. The focal length of the first objective lens
18
is taken to be fa, and the focal length of the second objective lens
19
is taken to be fb. Assuming the focal point of the first objective lens
18
and the focal point of the second objective lens
19
are consistent with each other, the image of the collimated light beam incident upon the first objective lens
18
will be formed temporarily at the focal position fa and have an image height Y. Then, the incident light is emitted again from the second objective lens
19
as a collimated light beam. At this time, between the incident angle &thgr;
in
of the incident light beam and the exit angle &thgr;
out
of the outgoing light beam, the following relation is established:
&thgr;
out
=r·&thgr;
in
where r is angular magnification (fa/fb).
Next, as shown by a broken line in FIG.
10
(
b
), by moving the second objective
19
by &Dgr;X in a direction of arrow along the optical axis O, the image of the laser light is formed in an irradiated object. In this case, in accordance with a distance from the second objective lens
19
to the irradiated object, an error &Dgr;&thgr;
out
occurs in the exit angle &thgr;
out
(S) of an outgoing light beam when the outgoing light beam is emitted to infinity, so that correction accuracy in the exit angle of the outgoing light beam is degraded. Reference character S denotes a distance from the second objective lens
19
to an irradiated object in the optical axis direction (i.e., a distance to an image-formed position).
SUMMARY OF THE INVENTION
The present invention has been made in view of the aforementioned disadvantages. Accordingly, it is an object of the present invention to provide a laser beam direction correcting optical system for a surveying instrument which is capable of imaging laser light in an irradiated object while avoiding correction accuracy degradation in the exit angle of an outgoing light beam.
To achieve this end and in accordance with one important aspect of the present invention, there is provided a laser beam direction correcting optical system for a surveying instrument, comprising: a laser light source for emitting laser light; an exit angle correcting means for correcting an exit angle of the laser light emerging therefrom in accordance with an inclination of an instrument main body so that the laser light is oriented in a specific direction; and an incident angle correcting means provided between the laser light source and the exit angle correcting means to correct an incident angle of the laser light incident upon the exit angle correcting means in accordance with the inclination of the instrument main body; wherein the exit angle correcting means comprises an objective lens, the objective lens being constituted by a variable-focus lens in which a positio
Ishinabe Ikuo
Kodaira Jun-ichi
Ohtomo Fumio
Foley & Lardner
Guadalupe Yaritza
Gutierrez Diego
Kabushiki Kaisha Topcon
LandOfFree
Laser beam direction correcting optical system for a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Laser beam direction correcting optical system for a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laser beam direction correcting optical system for a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2539977