Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1998-04-08
2001-02-13
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S239000
Reexamination Certificate
active
06188062
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to semiconductor laser and detector devices, and in particular to those for generating multiple beams. U.S. Pat. No. 5,285,062 described a laser/detector for use in optical pickups. In that device, as shown in
FIG. 1
, a laser chip 110 is mounted on top of a multiple element detector 120 which contains light sensitive elements for detecting a returned beam from a medium and also the back emission of the edge emitting laser chip 110. The mirror 150 redirects the light upwards towards the medium. The mirror surface is also corrugated to split the laser beam from laser chip 110 into 3 beams. Holographic element 160 is used to diffract a portion of the returned beam to light sensitive elements on detector 120. A ceramic substrate 130 supports the integrated laser/detector device. A retainer 180 holds together the mirror 150, hologram 160 with its holder 170 and the ceramic substrate 130 to complete the device.
One type of semiconductor laser is called a surface emitting laser. One structure for a surface emitting laser uses a semiconductor lasing device which emits the laser beam into a groove in the semiconductor chip. The opposite end of a groove includes a mirror for directing the laser beam from the surface of the semiconductor chip. Such a device is shown, for instance, in FIG. 2B of U.S. Pat. No. 4,906,839.
SUMMARY OF THE INVENTION
The present invention is an improvement over U.S. Pat. No. 5,285,062 in that the turning mirror is integrated into the photo detector chip. This allows a smaller package for the device and a simpler method for producing the laser/detector device. The laser beam of the apparatus of this invention is emitted along the surface of the chip towards a groove cut in the chip. A mirror is mounted in the groove, and the mirror has a corrugated structure so that it will reflect the beam and convert it into multiple beams at the same time.
In one embodiment, the invention includes a multiple element photo detector on the other side of the mirror for detecting the returned, diffracted light. The apparatus may be encapsulated in a clear plastic, with a diffraction grating mounted above the mirror to diffract the light on the return path.
For further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.
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Abstract/Zusammenfassung/Abrege—XS 9930204510 MA.
Hoetron, Inc.
Lee John R.
Townsend and Townsend / and Crew LLP
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