Optical pickup

Claim 2

An information reproducing system comprising a semiconductor laser device arranged to project a laser beam onto an optical disc containing information for reflection therefrom, means to oscillate said semiconductor laser device for driving said semiconductor laser device in a multiple longitudinal mode, optical means provided between said semiconductor laser device and the optical disc for deriving a beam of the reflection of the laser beam from the optical disc, and photoelectric conversion means responsive to the beam derived by said optical means for providing an output signal corresponding to the information contained on the optical disc.

Claim 3

An information reproducing system according to claim 1, wherein said semiconductor laser device is of the type which oscillates in a single longitudinal mode under a D.C. current drive.

Claim 4

An information reproducing system according to claim 1, wherein said optical means deflects the reflection of the laser beam from the optical disc away from the optical path between said semiconductor laser device and the optical disc onto said photoelectric conversion means.

Claim 5

An information reproducing system according to claim 3, wherein said optical means includes a quarter-wave plate and a polarization prism.

Claim 6

An information reproducing system according to claim 1, wherein said means to oscillate said semiconductor laser device includes means for supplying a D.C. current and a high-frequency current superposed thereon for driving said semiconductor laser device in the multiple longitudinal mode.

Claim 7

An information reproducing system according to claim 5, wherein the high-frequency current is a frequency at least five times the frequency of the information contained on the optical disc.

Claim 8

An information reproducing system according to claim 6, wherein the high-frequency current is a frequency of at least 50 MHz.

Claim 9

An information reproducing system comprising a semiconductor laser device arranged to project a laser beam onto an optical disc containing information and to receive a reflection therefrom, means to oscillate said semiconductor laser device in a multiple longitudinal mode, said means to oscillate including means to supply a D.C. current and a high-frequency current superposed thereon for driving said semiconductor laser device in the multiple longitudinal mode, and a photoelectric conversion device which derives an output of said laser device in accordance with the reflection from the optical disc and detects a variation thereof as an indication of the information on the optical disc.

Claim 10

An information reproducing system comprising a semiconductor laser device arranged to project a laser beam onto an optical disc containing information and to receive a reflection therefrom, means to oscillate said semiconductor laser device in a multiple longitudinal mode, said means to oscillate including means to supply a D.C. current and a high-frequency current superposed thereon for driving said semiconductor laser device in the multiple longitudinal mode, and a photoelectric conversion device which derives an output of said laser device in accordance with the reflection from the optical disc and detects a variation thereof as an indication of the information on the optical disc.

Claim 11

An information reproducing system according to claim 8, wherein the high-frequency current is a frequency at least five times the frequency of the information contained on the optical disc.

Claim 12

An information reproducing system according to claim 9, wherein the high-frequency current is a frequency of at least 50 MHz.

Claim 13

An information reproducing system according to claim 8, wherein said semiconductor laser is of the type which oscillates in a single longitudinal mode under a D.C. current drive.

Claim 14

An information reproducing system for reproducing information stored on an optical disc comprising semiconductor laser means driven for projecting a laser beam onto the optical disc for reflection therefrom, photoelectric conversion means responsive to an output of said laser means for providing an output indicative of the information stored on the optical disc, and means for reducing noise generated in the information reproducing system, said noise reducing means including driving means for driving and oscillating said laser means in a multiple longitudinal mode.

Claim 15

An information reproducing system for reproducing information stored on an optical disc comprising semiconductor laser means driven for projecting a laser beam onto the optical disc for reflection therefrom, photoelectric conversion means responsive to an output of said laser means for providing an output indicative of the information stored on the optical disc, and means for reducing noise generated in the information reproducing system, said noise reducing means including driving means for driving and oscillating said laser means in a multiple longitudinal mode.

Claim 16

An information reproducing system according to claim 12, wherein said driving means includes means for supplying a D.C. current and a high-frequency current superposed thereon for oscillating said laser means in a multiple longitudinal mode.

Claim 17

An information reproducing system according to claim 13, wherein the high-frequency current is a frequency of at least 50 MHz.

Claim 18

An information reproducing system according to claim 13, wherein the high-frequency current is a frequency at least five times the frequency of the information stored on the optical disc.

Claim 19

An information reproducing system according to claim 15, wherein the high-frequency current is a frequency of at least 50 MHz.

Claim 20

An information reproducing system according to claim 12, wherein said photoelectric conversion means is responsive to the reflection of the laser beam projected onto the optical disc for providing an output indicative of the information stored on the optical disc.

Claim 21

An information reproducing system according to claim 17, further comprising optical means provided between said semiconductor laser means and the optical disc for deriving a beam of the reflection of the laser beam projected onto the optical disc, said photoelectric conversion means being responsive to the beam derived by said optical means for providing an output indicative of the information stored on the optical disc.

Claim 22

An information reproducing system according to claim 18, wherein the high-frequency current is a frequency at least five times the frequency of the information stored on the optical disc.

Claim 23

An information reproducing system according to claim 19, wherein the high-frequency current is a frequency of at least 50 MHz.

Claim 24

An information reproducing system according to claim 12, wherein said semiconductor laser means oscillates in a single longitudinal mode under a D.C. current drive.