JPS5738403A - Focal point detector - Google Patents
Focal point detectorInfo
- Publication number
- JPS5738403A JPS5738403A JP11445380A JP11445380A JPS5738403A JP S5738403 A JPS5738403 A JP S5738403A JP 11445380 A JP11445380 A JP 11445380A JP 11445380 A JP11445380 A JP 11445380A JP S5738403 A JPS5738403 A JP S5738403A
- Authority
- JP
- Japan
- Prior art keywords
- block
- photodetector
- disk
- inexpensive
- focal point
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0908—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/30—Systems for automatic generation of focusing signals using parallactic triangle with a base line
- G02B7/32—Systems for automatic generation of focusing signals using parallactic triangle with a base line using active means, e.g. light emitter
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
- Automatic Focus Adjustment (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
PURPOSE:To obtain an inexpensive focal point detector having high sensitivity and a facilitated production, by forming both a beam splitter that leads the reflected light of the beams focused on a subject to be irradiated to a photodetector and a detecting prism into a body. CONSTITUTION:The beams (linearly polarized within the paper surface) emitted from a laser beam source 1 are focused on a disk 6 including an information track via a collimator lens 2, a block 14, a beam splitting surface 3a, a block 13, a 1/4 wavelength plate 4 and an objective lens 5 respectively. The reflected light is made incident to the block 13 via the plate 4 and reflected on the surface 3a and a reflecting surface 15 to be received at a photodetector 12. The surface 15 is set equal to or little smaller than the critical angle to the incident light in a focusing state. Thus the volume of incident light varies to light receiving regions 12A and 12B if the disk 6 has a displacement toward the direction (a) or (b) and becomes out of focus. In such way, an inexpensive focus detector can be obtained with high sensitivity and a facilitated production.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11445380A JPS5738403A (en) | 1980-08-19 | 1980-08-19 | Focal point detector |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11445380A JPS5738403A (en) | 1980-08-19 | 1980-08-19 | Focal point detector |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5738403A true JPS5738403A (en) | 1982-03-03 |
JPS639306B2 JPS639306B2 (en) | 1988-02-26 |
Family
ID=14638104
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11445380A Granted JPS5738403A (en) | 1980-08-19 | 1980-08-19 | Focal point detector |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5738403A (en) |
-
1980
- 1980-08-19 JP JP11445380A patent/JPS5738403A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS639306B2 (en) | 1988-02-26 |
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