Coherent light generators – Particular beam control device
Reexamination Certificate
2002-11-19
2004-09-28
Wong, Don (Department: 2828)
Coherent light generators
Particular beam control device
C372S023000, C372S043010, C372S098000, C372S108000
Reexamination Certificate
active
06798794
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor laser device, an astigmatic correction plate used therefor and a method of arranging the astigmatic correction plate.
2. Description of the Related Art
A typical semiconductor laser has a large number of characteristics, such as compact size, high efficiency, capability of low voltage operation, low power consumption, long life span, capability of high speed modulation and so on, so it is applicable as a light source for optical electronics, such as for optical communications or for reading data from an optical storage medium in various fields. Such a semiconductor laser device emits one kind of a laser beam from one element; however, as a derivative of the device, two-wavelength semiconductor laser devices emitting two kinds of laser beams with different wavelengths from one element have been proposed in, for example, Japanese Unexamined Patent Application Publication No. Hei 10-302289, Japanese Unexamined Patent Application Publication No. Hei 09-283853, Japanese Unexamined Patent Application Publication No. Hei 02-253676, Japanese Unexamined Patent Application Publication No. Sho 56-80195, Japanese Unexamined Patent Application Publication No. Sho 60-164381, Japanese Patent Publication No. 3095036, Japanese Patent Publication No. 3197050 and so on, and some of them are already in practical use.
FIG. 1
shows an example of such conventional two-wavelength semiconductor laser device. In the conventional two-wavelength semiconductor laser device, on a laser diode chip
16
with, for example, a double heterojunction structure, a first laser light source
11
of a light emitting point which emits a laser beam with a predetermined wavelength is arranged, and a second laser light source
12
which emits a laser beam with a different wavelength from that of the laser beam emitted from the first laser light source
11
is arranged at a predetermined distance from the first laser light source
11
. In order to correct the astigmatism of the laser beams emitted from the first laser light source
11
and the second laser light source
12
, an astigmatic correction plate
13
is arranged so as to intersect diagonally the optical axes of the laser beams.
The astigmatic correction plate
13
is arranged on a backside of a top surface of a so-called slanted cap
18
having an aperture with a predetermined effective diameter. The slanted cap
18
is arranged so as to cover the laser diode chip
16
, and thereby a main surface of the astigmatic correction plate
13
intersects diagonally optical axes
15
and
19
of the laser beams emitted from the laser diode chip
16
.
In such two-wavelength semiconductor laser device, as shown in
FIG. 2
, the astigmatic correction plate
13
is arranged in a slanting position, so the optical axes
15
and
19
of the laser beams are shifted due to refraction in the astigmatic correction plate
13
. Therefore, the first laser light source
11
is arranged in a position shifted from a center line (CL) of the effective diameter of the aperture on purpose.
On the other hand, in much the way that the position of the first laser light source
11
is shifted, the second laser light source
12
is arranged in a position shifted by a predetermined distance from the first laser light source
11
to a direction in which a distance to the main surface of the astigmatic correction plate
13
becomes longer.
However, in the above, conventional two-wavelength semiconductor laser device, as schematically shown in
FIG. 3
, there is a problem that, specifically, an emission angle (a region capable of emission) of the laser beam emitted from the second laser light source
12
becomes extremely narrow.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a semiconductor device capable of increasing an emission angle of a laser beam, an astigmatic correction plate used therefor and a method of arranging the astigmatic correction plate.
A semiconductor laser device emitting two wavelengths different from each other according to the invention comprises: a first laser light source emitting a laser beam with a first wavelength; a second laser light source arranged at a predetermined distance from the first laser light source emitting a laser beam with a second wavelength; and an astigmatic correction plate comprising a light transmitting plate with a predetermined thickness, the astigmatic correction plate being arranged so as to intersect diagonally an optical center line or an optical axis of at least one of the laser beams emitted from the first laser light source and the second laser light source in order to correct the astigmatism of the laser beam, and emitting the laser beam from an aperture with a predetermined effective diameter to outside, wherein the first laser light source and the second laser light source are arranged on both sides of a center line of the effective diameter so as to have different distances to the astigmatic correction plate in a direction parallel to the optical center line or the optical axis.
Another semiconductor laser device emitting two wavelengths different from each other according to the invention comprises: a first laser light source emitting a laser beam with a first wavelength; a second laser light source arranged at a predetermined distance from the first laser light source emitting a laser beam with a second wavelength; and an astigmatic correction plate comprising a light transmitting plate with a predetermined thickness, the astigmatic correction plate being arranged so as to intersect diagonally an optical center line or an optical axis of at least one of the laser beams emitted from the first laser light source and the second laser light source in order to correct the astigmatism of the laser beam, and emitting the laser beam from an aperture with a predetermined effective diameter to outside, wherein the first laser light source is arranged in such a position that an optical center line or an optical axis of the first laser light source almost coincides with a center line of the effective diameter of the astigmatic correction plate, and the second laser light source is arranged so that a distance from the second laser light source to the astigmatic correction plate in a direction parallel to the optical center line or the optical axis is shorter than a distance from the first laser light source to the astigmatic correction plate.
In an astigmatic correction plate used for a semiconductor laser device according to the invention, the semiconductor laser device comprises a first laser light source emitting a laser beam with a first wavelength and a second laser light source arranged at a predetermined distance from the first laser light source emitting a laser beam with a second wavelength, and the astigmatic correction plate, which is arranged so as to intersect diagonally an optical center line or an optical axis of at least one of the laser beams emitted from the first laser light source and the second laser light source in order to correct the astigmatism of the laser beam, and which emits the laser beam from an aperture with a predetermined effective diameter to outside, comprises a light transmitting plate body with a predetermined thickness, wherein the astigmatic correction plate is arranged so that the first laser light source and the second laser light source have different distances to the astigmatic correction plate in a direction parallel to the optical center line or the optical axis, and the first laser light source and the second laser light source are arranged on both sides of a center line of the effective diameter.
In another astigmatic correction plate used for a semiconductor laser device according to the invention, the semiconductor laser device comprises a first laser light source emitting a laser beam with a first wavelength and a second laser light source arranged at a predetermined distance from the first laser light source emitting a laser beam with a s
Kananen Ronald P.
Menefee James
Rader & Fishman & Grauer, PLLC
Sony Corporation
Wong Don
LandOfFree
Semiconductor laser device, astigmatic correction plate used... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor laser device, astigmatic correction plate used..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor laser device, astigmatic correction plate used... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3186969