Optical signal recorders employing two lasers and methods therefor

In a optical head for an optical disk recorder, the improvement comprising:

• first and second lasers for emitting first and second light beams of substantially the same frequency and light beam intensity;
• circuit means connected to said first and second lasers for operating both said lasers at a same power level;
• thermal mounting means mounting said first and second lasers in high thermal conductive relationship such that the temperature of operations of the first and second lasers tend to be similar;
• a polarization-insensitive beam combiner having amorphous optical materials and being optically coupled to the lasers for transferring both beams along a single light path without altering the polarization of the two light beams and in a slightly diverging relationship;
• said beam combiner including first and second input surfaces disposed in two planes disposed at a small angle with respect to each other for effecting said small divergence of said first and second light beams for receiving said first and second light beams from said first and second lasers respectively and the beam combiner also including first and second closely-spaced-apart, parallel-extending optical surface means both inclined at a predetermined angle with respect to and crossing the light axis of said first laser emitted light beam for intercepting and attenuating the beam intensity of said first laser emitted light beam;
• and
• optical means in said single light path for introducing identical polarization changes to both said beams and a polarization-sensitive beam splitter optically interposed between said combiner and optical means for directing reflected light beams derived from said first and second light beams into two diverging light paths for enabling detection of one of said two reflected light beams.

In an optical signal recorder having an optical recording disk support for relatively moving an optical record disk with respect to optical transducer means movably supported with respect to the optical record disk;

• the improvement including a new optical transducer means, including the combination of:
• first and second laser means for operating at substantially the same frequency and for respectively emitting light beams along respective light axes and having similar wavelengths and light intensities respectively for reading and recording signals from and to the optical record disk;
• means for mounting both said laser means in close proximity and having a high thermal conductivity portion in a thermal conduction connection with both said laser means such that both of said laser means operate at substantially the same temperature;
• first optical means optically coupled to both said laser means for receiving both said emitted light beams and for combining same into a single light path, but in a diverging relationship to each other at a predetermined angle less than about one degree the first optical means including first and second closely-spaced-apart, parallel-extending optical surface means both inclined at a predetermined angle with respect to and crossing the light axis of said first laser means emitted light beam for intercepting and attenuating the beam intensity of said first laser means emitted light beam for such beam to serve as a read beam;
• and furthermore wherein said first optical means includes first and second input surfaces disposed in two planes disposed at a small angle with respect to each other for effecting said small divergence of said first and second light beams;
• second optical means optically coupled to said first optical means for receiving said diverging combined light beams and for transferring same to said optical record disk for respectively reading and recording signals from and on said optical record disk and for receiving light reflected from said optical record disk caused by at least one of said combined emitted light beams;
• and
• detector means in said second optical means for receiving said reflected light as received by said second optical means for detecting said reflected light to indicate its contained informational content.

In an optical information-bearing signal recorder having relatively movable record and transducer members, the improvement including, in combination:

• light path means for bidirectionally transmitting beams of light;
• first and second lasers respectively emitting first and second collimated light beams having similar power output levels, identical wavelengths and similar polarizations with respect to axes of the light beams, respectively, toward said light path means along a major axis;
• a nonpolarization-sensitive beam combiner optically coupled to said first and second lasers for receiving said first and second light beams from said lasers and in a manner so as to internally reflect the emitted second light beam in a predetermined portion of the beam combiner toward said light path means for transmission along a first direction and to transmit the emitted first light beam through the beam combiner toward said light path means without internal reflection also in said first direction toward said light path means and the beam combiner also including first and second closely-spaced-apart, parallel-extending optical surface means both inclined at a predetermined angle with respect to and crossing the light axis of said first laser emitted light beam for intercepting and attenuating the beam intensity of said first laser emitted light beam;
• and furthermore wherein said nonpolarization-sensitive beam combiner includes first and second input surfaces disposed in two planes at a small angle with respect to each other for effecting a small divergence of said first and second collimated light beams;
• a polarization-sensitive beam splitter, including a quarter-wave plate, optically coupled to said beam combiner for receiving said first and second light beams travelling in said first direction along said axis and being coupled to said light path means for transmitting both of said emitted light beams to the light path means and for receiving light beams from the light path means;
• objective lens means optically coupled to said polarization beam splitter through said light path means for receiving said transmitted light beams and directing same to said record member and for transmitting reflected light beams received from said record member through said light path means to said polarization beam splitter such that the polarization beam splitter directs said record member reflected light beams away from said beam combiner;
• and
• detector means optically coupled to said polarization-sensitive beam splitter for receiving the polarization beam splitter directed beam corresponding to said emitted first light beam whereby focus, tracking and data detection is achievable based upon said emitted first light beam and recording of signals is achievable by said emitted second light beam.

In an optical head for an optical disk recorder, the improvement comprising:

• first and second lasers for emitting first and second light beams of substantially the same frequency and light beam intensity;
• thermal mounting means mounting said first and second lasers in high thermal conductive relationship such that the temperature of operations of the first and second lasers tend to be similar;
• a polarization-insensitive beam combiner having amorphous optical materials and being optically coupled to the lasers for transferring both the beams along a single light path without altering the polarization of the two light beams and in a slightly diverging relationship, means in said combiner for attenuating the light beam intensity of said first light beam sufficiently to enable the attenuated light beam to read recorded information on an optical disk without altering the recording thereon;
• optical means in said single light path for introducing identical polarization changes to both said beams and a polarization-sensitive beam splitter optically interposed between said combiner and optical means for directing said light beams derived from said first and second light beams into two diverging light paths for enabling detection of one of said two reflected light beams;
• objective lens means having a predetermined focal length and said first and second light beams having a predetermined angle of divergence of not greater than one degree along said single light path, having a predetermined relationship to said focal length for achieving a predetermined physical separation of the said two light beams on an optical record member in said optical disk recorder;
• said beam combiner has a first optical element consisting of a predetermined amorphous optical material and having a first surface angled with respect to said emitted first and second light beams and disposed to receive and refract said emitted first light beam and being a part of said attenuator means and having a second input surface disposed to receive said second light beam such that said first surface intercepts the second light beam and internally reflects the second light beam but not as a part of said attenuator means, said refraction and reflection directing the light beams along a given light path having a major axis and said refracted and reflected light beams having a predetermined small angle of divergence;
• said first optical element includes an internal reflection surface optically interposed between said first angled surface and said second laser such that said second light beam is internally reflected a plurality of times within said first optical element;
• said first and second lasers being disposed with respect to each other to emit substantially parallel spaced-apart beams of light;
• an input optical element having an input optical surface orthogonally disposed with respect to said first light beam for intercepting same and having an angled surface forming a part of said attenuator means and which is disposed parallel to in an optically-closely-spaced-apart relationship to said first angled surface and wherein said first angled surface forms a second part of a said attenuator means;
• means bonding said input and first optical elements as a unitary member;
• means bonding said optical means to said first optical element to form an optical composite elongated along said major axis and disposed with respect to said beam combiner for receiving said diverging first and second light beams;
• a one-half-wave-length plate disposed between said beam combiner and said optical means and bonded to both said beam combiner and said optical means;
• a quarter-wave optical plate bonded to said polarization-sensitive beam splitter remote from said beam combiner and facing away therefrom;
• a mirror disposed at a predetermined angle with respect to said major axis for receiving and reflecting said diverging light beams to an optical record member through said objective lens, wherein said angle of divergence is relatable to the focal length of said focuser from said beam combiner to said optical record disk via said mirror;
• said beam combiner has first and second input surfaces respectively disposed substantially orthogonal to the beams emitted by said first and second lasers and said beam combiner having an output surface disposed substantially orthogonal to said major axis;
• said first optical element includes a third angled surface facing away from said first angled surface and being disposed in a plane substantially parallel thereto, and said second input surface intercepting said second light beam from said second laser means for projecting the received second light beam to said third angle surface for internally reflecting same to said first angled surface such that, that first angled surface internally reflects said second beam along said major axis;
• and
• said second input surface being disposed in a plane at a predetermined small angle with respect to said output surface for achieving said diverging of said first and second light beams along said major axis.