Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal
Reexamination Certificate
2000-07-12
2002-03-19
Picardat, Kevin M. (Department: 2823)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
C438S038000, C438S041000, C438S046000
Reexamination Certificate
active
06358764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor light emitting device and a method of producing the same, more particularly relates to a semiconductor light emitting device having a plurality of semiconductor light emitting elements for emitting a plurality of types of light having different wavelengths and a method of producing the same.
2. Description of the Related Art
An optical pickup is generally built into apparatuses for reading (reproducing) information recorded on a Compact Disk (CD), a Digital Video Disk (DVD), a Mini Disk (MD), or other optical recording medium optically recording information (hereinafter also referred to as an optical disk) or for writing (recording) information on the same (hereinafter also referred to as optical disk apparatuses).
In the above optical disk apparatuses and optical pickups, different wavelengths of laser light are generally used in different kinds of optical disks (optical disk systems). Laser light having a wavelength of 780 nm is used for playing a CD, while laser light having a wavelength of 650 nm is used for playing a DVD.
Under these conditions, where different wavelengths of laser light are used depending on the kinds of the optical disks, a compatible optical pickup which enables, for example, a CD to be played in a DVD optical disk apparatus has been desired.
FIG. 1
is a view of the configuration of a compatible optical pickup provided with a CD laser diode LD
1
(emission wavelength of 780 nm) and a DVD laser diode LD
2
(emission wavelength of 650 nm) so as to enable playback of a CD and DVD as a first example of the related art.
An optical pickup
100
includes a separately configured, that is, discretely composed CD optical system comprised of, for example, a first laser diode LD
1
for emitting laser light having a wavelength of for example the 780 nm band, a grating G, a first beam splitter BS
1
, a first mirror M
1
, a first object lens OL
1
, a first multiple lens ML
1
, and a first photodiode PD
1
, arranged at predetermined positions.
Furthermore, the above optical pickup
100
includes a DVD optical system comprising, for example, a second laser diode LD
2
for emitting laser light having a wavelength of for example the 650 nm band, a second beam splitter BS
2
, a collimeter C, a second mirror M
2
, a second object lens OL
2
, a second multiple lens ML
2
, and a second photodiode PD
2
arranged at predetermined positions.
In the CD optical system of the optical pickup
100
of the above configuration, the first laser light L
1
from the first laser diode LD
1
passes through the grating G, is partially reflected by the first beam splitter BS
1
, is bent in course by the first mirror M
1
, and then is converged on an optical disk D by the first object lens OL
1
.
The reflected light from the optical disk D passes through the first multiple lens ML
1
via the first object lens OL
1
, the first mirror M
1
, and the first beam splitter BS
1
and strikes the first photodiode PD
1
. The information recorded on the CD recording surface of the optical disk D is read by the changes of this reflected light.
In the DVD optical system of the optical pickup
100
of the above configuration as well, in the same way as the above, the laser light L
2
from the second laser diode LD
2
is partially reflected by the second beam splitter BS
2
, passes through the collimeter C, is bent in its course by the second mirror M
2
, and then is converged on the optical disk D by the second object lens OL
2
.
The reflected light from the optical disk D passes through the second multiple lens ML
2
via the second object lens OL
2
, second mirror M
2
, collimeter C, and second beam splitter BS
2
and strikes the second photodiode PD
2
. The information recorded on the DVD recording surface of the optical disk D is read by the changes of this reflected light.
The above optical pickup
100
makes it possible to play back both CD and DVD by providing a CD laser diode, a DVD laser diode, and respective optical systems.
FIG. 2
is a view of the configuration of a compatible optical pickup provided with a CD laser diode LD
1
(emission wavelength of 780 nm) as in the above and a DVD laser diode LD
2
(emission wavelength of 650 nm) so as enable playback of a CD and DVD as a second example of the related art.
An optical pickup
101
contains a separately configured, that is, discretely composed CD optical system comprising, for example, a first laser diode LD
1
for emitting laser light having a wavelength of for example the 780 nm band, a grating G, a first beam splitter BS
1
, a dichroic beam splitter DBS, a collimeter C, a mirror M, a CD aperture R, an object lens OL, a first multiple lens ML
1
, and a first photodiode PD
1
, arranged at predetermined positions.
Furthermore, the above optical pickup
101
contains a DVD optical system comprising, for example, a second laser diode LD
2
for emitting laser light having a wavelength of for example the 650 nm band, a second beam splitter BS
2
, the dichroic beam splitter DBS, the collimeter C, the mirror M, the object lens OL, a second multiple lens ML
2
, and a second photodiode PD
2
arranged at predetermined positions.
In the above optical systems, some of the optical members are used in common, for example, the dichroic beam splitter DBS, the collimeter C, the mirror M, and the object lens OL are commonly used by the two optical systems. Since the dichroic beam splitter DBS and the optical disk D share the same optical axis, a CD aperture R is provided on the optical axis of the DVD optical system as well.
In the CD optical system of the optical pickup
101
of the above configuration, the first laser light L
1
from the first laser diode LD
1
passes through the grating G, is partially reflected by the first beam splitter BS
1
, passes through or is reflected at the dichroic beam splitter DBS, the collimeter C, and the mirror M, and then is converged on the optical disk D by the object lens OL via the CD aperture R.
The reflected light from the optical disk D passes through the first multiple lens ML
1
via the object lens OL, the CD aperture R, the mirror M, the collimeter C, the dichroic beam splitter DBS, and the first beam splitter BS
1
and strikes the first photodiode PD
1
. The information recorded on the CD recording surface of the optical disk D is read by the change of this reflected light.
In the DVD optical system of the optical pickup
101
of the above configuration as well, in the same way as the above, the laser light L
2
from the second laser diode LD
2
is partially reflected by the second beam splitter BS
2
, passes through or is reflected at the dichroic beam splitter DBS, the collimeter C, and the mirror M, and then is converged on the optical disk D by the object lens OL via the CD aperture R.
The reflected light from the optical disk D passes through the second multiple lens ML
2
via the object lens OL, the CD aperture R, the mirror M, the collimeter C, the dichroic beam splitter DBS, and the second beam splitter BS
2
and strikes the second photodiode PD
2
. The information recorded on the DVD recording surface of the optical disk D is read by the changes in this reflected light.
According to the above optical pickup
101
, in the same way as in the optical pickup
100
shown in
FIG. 1
, it is made possible to play back both CD and DVD by providing a CD laser diode and a DVD laser diode and respective optical systems.
Summarizing the problems to be solved by the present invention, the above optical pickups have a large number of parts and the optical systems are complicated in configuration, so it is not easy to assemble the pickups, it is difficult to make the optical device compact, and, furthermore, the cost inevitably becomes higher.
In the above optical pickups of the related art, one of the reasons why the number of parts was large and the optical system became complex in configuration was that the CD laser diode and the DVD laser diode were separately provided.
An example of a laser diode used in the abo
Collins D. M.
Picardat Kevin M.
Sonnenschein Nath & Rosenthal
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