Optical head

Details Optical head Optical head

2000-01-11

2001-06-26

Edun, Muhammad (Department: 2651)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S044230, C369S044410

Reexamination Certificate

active

06252833

ABSTRACT:

RELATED APPLICATIONS
The present application claims priority to Japanese Patent Application No. 11-10238 filed Jan. 19, 1999, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to an optical head, and particularly, to an optical head used for high-density optical recording and reading onto and from optical recording media.
2. Description of the Related Art
In recent years, in the field of optical memories for optical recording and reading of information, an optical head being capable of recording a larger amount of information, that is, having a remarkably improved recording density has been required with increase in speed of computers and development of multimedia. As a technology to record and read information at high densities, a near-field light recording technology has been proposed. In conventional optical memories using laser beams, the upper limit of the recording density depends on the diffraction limit of light, so that only a mark of approximately the wavelength of light (approximately several hundred nanometers) can be recorded and read out.
In an optical memory using a near-field light phenomenon which has been proposed in recent years, a mark of several tens of nanometers smaller than the diffraction limit of light can be written as a signal and read out by applying light for recording and reading under a condition where a probe having a fine opening of not more than the wavelength of light or an optical head using a solid immersion lens has been brought near to the recording medium (optical disk) until it is only several tens of nanometers away therefrom.
In a case where information on a recording medium is read out by use of near-field light, reflected light converted into propagation light and reflected is detected. However, since the use efficiency of near-field light is, intrinsically, considerably low, it is necessary to efficiently detect the reflected light.
As a technology to detect the reflected light for reading, a near-field optical microscope in which a fine opening array and a photoelectric array are integrally formed is disclosed in Japanese Laid-open Patent Application No. 5-164968. Moreover, an integrated probe in which a photodetector is integrated is described on page 579 of Applied Physics Letter No. 68 (1996). However, it is the present state that desired detection efficiency cannot always be obtained even with these detection technologies.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-mentioned problem.
Another object of the present invention is to provide an optical head using the near-field light phenomenon, said optical head being capable of efficiently detecting the reflected light for reading.
These and other objects are achieved by an optical head comprising near-field light generating device for generating near-field light; a semiconductor substrate situated in a near-field area or in a vicinity thereof; a photodetector for detecting reflected light, from a recording layer, of the near-field light generated by the near-field light generating device, said photodetector being formed on the semiconductor substrate.
In the present invention, to read information on the recording layer, reflected light being converted into propagation light at the recording layer and reflected is read by the photodetector. The photodetector being formed in the near-field area or in the vicinity thereof is situated extremely close to the recording layer, so that the reflected light is more efficiently detected than ever. In addition, since the photodetector is integrally formed on the substrate made of a semiconductor material, the space can efficiently be used, which greatly contributes to weight reduction of the optical head.
Further, the photodetector can be manufactured by an ordinary semiconductor process and is excellent in mass productivity. In this respect, it is preferable that a photodiode be formed on the semiconductor substrate as the photodetector.
The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 5828644 (1998-10-01), Gage et al.
patent: 5881042 (1999-03-01), Knight
patent: 5-164968 (1993-06-01), None

Affiliated with

Also associated with

Rating

Optical head does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical head will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2495149