JPS61140430U

JPS61140430U -

Info

Publication number: JPS61140430U
Application number: JP2341985U
Authority: JP
Priority date: 1985-02-22
Filing date: 1985-02-22
Publication date: 1986-08-30

Description

[Brief explanation of the drawing]

第１図は本考案の一実施例となる光学装置の構
成を示す概略図、第２図は上記光学装置によつて
形成されるデイスク上の光スポツトを示す平面図
、第３図は上記光学装置の回路の要部を示すブロ
ツク図、第４図は従来の光学装置の概略図、第５
図は第４図の光学装置の回路の要部を示すブロツ
ク図である。１……レーザ源、２……ミラー、２Ａ……半反
射面、２Ｂ……全反射面、３……第１のレーザビ
ーム、３Ａ……戻りビーム、４……第２のレーザ
ビーム、４Ａ……戻りビーム、５……対物レンズ
、８……デイスク、８Ａ……信号記録面、９……
光スポツト、１０……ピツト、１１……光スポツ
ト、１２，１４……デイテクタ、１３，１５……
光スポツト、３０……偏光ビームスプリツタ。 FIG. 1 is a schematic diagram showing the configuration of an optical device that is an embodiment of the present invention, FIG. 2 is a plan view showing a light spot on a disk formed by the optical device, and FIG. 3 is a plan view showing the optical spot formed by the optical device. A block diagram showing the main parts of the circuit of the device, FIG. 4 is a schematic diagram of a conventional optical device, and FIG.
This figure is a block diagram showing the main parts of the circuit of the optical device shown in FIG. 4. 1...Laser source, 2...Mirror, 2A...Semi-reflection surface, 2B...Total reflection surface, 3...First laser beam, 3A...Return beam, 4...Second laser beam, 4A ... Return beam, 5 ... Objective lens, 8 ... Disk, 8A ... Signal recording surface, 9 ...
Light spot, 10... pit, 11... light spot, 12, 14... detector, 13, 15...
Optical spot, 30...Polarizing beam splitter.

Claims

[Scope of utility model registration request]

A beam emitted from a laser source is focused onto a disk via an optical means, a return beam from the disk is guided onto a first detector, and a focus error is detected according to the beam diameter of the guided beam. In the optical device, the beam emitted from the laser source is guided to an optical element having a first reflective surface and a second reflective surface that totally reflects the beam that has passed through the first reflective surface. , the first beam reflected by the first reflecting surface and the second beam
An optical path difference is created between the second beam reflected by the reflective surface of the disc, and the first beam is passed through the optical means into a small diameter beam that can read the bits etc. recorded on the disk. Let it converge,
The return beam from the disk is guided onto the second detector so that a reproduction signal of the recorded information can be obtained, and the beam is transmitted through the optical means to the second detector.
The beam is converged to a larger diameter beam than the small diameter beam so as to span a plurality of pits etc. recorded on the disk, and the return beam from the disk is guided to the first detector. optical equipment.