公开(公告)号：JPH0963073A

公开(公告)日：1997-03-07

申请号：JP21066695

申请日：1995-08-18

Applicant: SONY CORP

Inventor： EGUCHI NAOYA ,  BUIHIMAN BUERUNA

IPC: G11B11/10 ,  G11B7/09 ,  G11B7/135 ,  G11B11/105

Abstract: PROBLEM TO BE SOLVED: To miniaturize a device and to reduce cost of the device by providing an optical element having a uniaxial double refractivity to reduce the number of components, to dispense with adjustments of photodetectors and to obtain a constant servo signal. SOLUTION: An objective lens 4 condenses the laser emitted from a laser diode 1 being a light source at one point on an optical axis. A photodetector 6 receives the reflected laser beam from a magneto-optical disk 5 of the laser beam condesed by the objective lens 4 and made to be radiated on the signal recording surface of the magneto-optical disk 5. An optical element 3 having the uniaxial double refractivity is inclinedly provided between the objective lens 4 and the photodetector 6 and separates the laser beam to be emitted from the laser diode 1 from the reflected laser beam to be made incident via the objective lens 4 and moreover separates transmission optical paths of an ordinary ray and an extraordinary ray by walk-off effect.

公开(公告)号：JPH08129773A

公开(公告)日：1996-05-21

申请号：JP26500994

申请日：1994-10-28

Applicant: SONY CORP

Inventor： EGUCHI NAOYA ,  BUIHIMAN BUERUNA

IPC: G11B7/135

Abstract: PURPOSE: To realize a smaller size and lower cost by decreasing the number of parts, eliminating the need for adjustment of a photodetector and obtaining a stable servo signal. CONSTITUTION: The laser beam emitted from a laser diode 1 is partly reflected on the surface of an optical element 2 which is disposed diagonally between an objective lens 3 and a photodetector 5 and has uniaxial double refractiveness. This laser beam is introduced to the objective lens 3. The objective lens 3 condenses the laser beam and casts the laser beam to the signal recording surface of the disk 4. The return light reflected on the signal recording surface of the disk 4 arrives again at the optical element 2 having the uniaxial double refractiveness via the objective lens 3. The optical element 2 having the uniaxial double refractiveness allows the transmission of part of the return light and makes the light incident on the photodetector 5.

公开(公告)号：JPH07131101A

公开(公告)日：1995-05-19

申请号：JP27846993

申请日：1993-11-08

Applicant: SONY CORP

Inventor： BUIHIMAN BUERUNA ,  OKA MICHIO

IPC: G02B5/30 ,  G02F1/37 ,  H01S3/094 ,  H01S3/109 ,  H01S3/136

Abstract: PURPOSE:To stably generate a second harmonic, using an Nd:YVO4 birefringence laser medium, by orienting the c-axis of the medium in the same direction as that of a crystal of a nonlinear optical crystal element. CONSTITUTION:A laser beam is emitted as a pumping beam from a laser diode 11, i.e., a semiconductor laser element as a pumping light source element. This beam is focused by a lens 12 and applied to a laser medium 16 made of Nd: YVO4 through a reflection mirror 14 of a laser resonator 13 and a quarter-wave plate 15. The mirror 14 uses a concave mirror having a concave face inside. The medium 16 generates a fundamental wave of the laser beam in response to the incidence of the excited beam, and this wave passing through a nonlinear optical crystal element 17 using e.g. KTP is reflected by a reflection mirror 18. The c-axis of the Nd:YVO4 of the medium 16 is oriented in the same direction as that of a KTP crystal of the element 17.

公开(公告)号：JPH0845103A

公开(公告)日：1996-02-16

申请号：JP17820594

申请日：1994-07-29

Applicant: SONY CORP

Inventor： EGUCHI NAOYA ,  BUIHIMAN BUERUNA

IPC: G11B11/10 ,  G11B7/135 ,  G11B11/105

Abstract: PURPOSE:To realize miniaturization and cost reduction by decreasing the number of parts, eliminating the need for adjustment of a photodetector and obtaining a stable servo signal. CONSTITUTION:Since a laser beam of S-polarized light emitted from a laser diode 1 is an ordinary beam to an optical element 2 having double refractiveness, this beam is made incident on a quarter-wavelength plate 3 without being changed in the optical path. This quarter-wavelength plate 3 makes the laser beam described above into circularly polarized light. An objective lens 4 condenses the laser beam of the circularly polarized light to the signal recording surface of a disk 5. The return light reflected by the signal recording surface of the disk 5 is made incident again on the quarter-wavelength plate 3 via the objective lens. The quarter-wavelength plate 3 makes the incident return light into P-polarized light. The laser beam of the P-polarized light is an extraordinary beam to the optical element 2 having the double refractiveness. The optical element 2 having the double refractiveness changes the optical path of the P-polarized laser beam which is the extraordinary beam. The reflected return light from the disk 5 does not, therefore, return to the laser diode 1 and returns to the light condensing surface of the photodetector 6.

公开(公告)号：JPH07131100A

公开(公告)日：1995-05-19

申请号：JP27846893

申请日：1993-11-08

Applicant: SONY CORP

Inventor： BUIHIMAN BUERUNA ,  OKA MICHIO

IPC: G02B27/28 ,  G02F1/37 ,  H01S3/094 ,  H01S3/109 ,  H01S3/136

Abstract: PURPOSE:To suppress a variation in a retardation of a nonlinear optical crystal element and to stabilize its operation by providing a double refractive crystal element having a predetermined temperature dependence for cancelling temperature characteristics of a phase delay amount. CONSTITUTION:An exciting laser light emitted from a laser diode 11 is condensed by a lens 12, and incident to a laser medium 16 using, for example, Nd: YVO4 through a reflecting mirror 14 of a laser oscillator 13. A fundamental wave laser light generated from the medium 16 is reciprocated and advanced between reflecting surfaces 14A, 18R of the reflecting mirrors 14, 18 of the oscillator 13, passed through a nonlinear optical element 17 thereby to generate a second harmonic laser light, this SHG laser light is extracted through the mirror 18. Accordingly, influence of a temperature change of double refraction can be effectively removed by adding a double refractive crystal element (YVO4) 19 having predetermined temperature dependency, thereby obtaining a stable longitudinal single mode oscillation in a wide temperature range.