Mark B Freeman

US Patent:

6369377, Apr 9, 2002

Filed:

Jul 13, 2000

Appl. No.:

09/615412

Inventors:

Hsi-Fu Shih - Chang-Hua Hsien, TW
Jau-Jiu Ju - Chutung Hsinchu, TW
Tzu-Ping Yang - Taipei, TW
Wei-Chih Lu - Tainan, TW
Mark O. Freeman - San Mateo CA
Der-Ray Huang - Hsinchu, TW
Carl Y. Yang - Chutung Hsinchu, TW

Assignee:

Industrial Technology Research Institute - Hsinchu

International Classification:

G11B 700

US Classification:

250225, 2502015, 36911204, 36911205, 3691121, 36911215, 36911216, 36911212

Abstract:

The present invention discloses a multiple-beam holographic optical pick-up head, which has the advantages of the multiple-beam optical pick-up head and the holographic optical pick-up head and can increase the light usage efficiency. This invention uses the property that a polarized diffractive optical element can generate different optical effects for laser beam with different polarizations and places a polarized multiple-beam grating and polarized hologram on the optical path for splitting the incident light toward the disc into multiple reading beams by the multiple-beam grating. The returning laser beams reflected from the disc are diffracted and diverted by the hologram to reach a photodetector. Both the incident and reflective beams are diffracted once only; thus the light usage efficiency can be increased.

US Patent:

6377520, Apr 23, 2002

Filed:

Apr 21, 1998

Appl. No.:

09/063946

Inventors:

Mark O. Freeman - San Mateo CA
Jinn-Kang Wang - Yong-Ho, TW
Hsi-Fu Shih - Chang-Hua Hsien, TW

Assignee:

Industrial Technology Research Institute

International Classification:

G11B 700

US Classification:

369 4423, 369 4441

Abstract:

A focus/tracking method and system is provided for use in an optical drive with a possibly multiple-wavelength laser source for control of the focus/tracking of the pickup head of the optical drive. The use of a multiple-wavelength laser source allows the optical drive to read data from various types of optical discs. The focus/tracking method and system combines the use of a differential, dual optical channel method for focusing control of the laser beam used to read data from the optical disc and the use of the single-beam tracking method for tracking control of the same. The focus error signal and the tracking error signal can be obtained from the same set of multi-element photodetectors. The structure of the system can therefore be simplified to include a reduced number of constituent components thus allowing a reduction in manufacturing cost.

US Patent:

62115111, Apr 3, 2001

Filed:

Jan 8, 1999

Appl. No.:

9/227678

Inventors:

Hsi-Fu Shih - Chang-Hua Hsien, TW
Tzu-Ping Yang - Taipei, TW
Mark O. Freeman - San Mateo CA
Jinn-Kang Wang - Taipei Hsien, TW

Assignee:

Industrial Technology Research Institute - Hsinchu

International Classification:

H10J 4014

US Classification:

250214R

Abstract:

A dual-wavelength holographic laser module is provided. The dual-wavelength holographic laser module includes a holographic optical element (HOE), a multiple-element photodetector, and a laser light source that can produce a laser light with a wavelength that has, for example, two desired quantities. The laser light emitted from the laser light source with a desired wavelength can travel through the HOE and an objective lens unit, which is used to focus the laser light onto an optical disk of the DVD system, the CD system, or the CD-R system, depending on which wavelength quantity is chosen. The objective lens unit includes a single lens with a changeable NA quantity or a two-lens system that can be switched to put one lens at a time in the optical path. The optical disk reflects the laser light back to the HOE along the same light path. The reflected laser light is diffracted by the HOE to reach to the multiple-element photodetector.

US Patent:

61881325, Feb 13, 2001

Filed:

Apr 21, 1998

Appl. No.:

9/063738

Inventors:

Hsi-Fu Shih - Changhua Hsien, TW
Tzu-Ping Yang - Taipei, TW
Jinn-Kang Wang - Taipei Hsien, TW
Mark O. Freeman - San Mateo CA

Assignee:

Industrial Technology Research Institute

International Classification:

H01L 2334

US Classification:

257724

Abstract:

A two-wavelength laser diode package is provided, which can be utilized in the read/write head of an optical drive capable of reading data from different types of optical discs, such as CD (compact disc), CD-R (CD Recordable) and DVD (digital versatile disc). The laser diode package includes a pair of laser diodes of two different specifications in wavelength, which are disposed on one or two submounts, either horizontally or vertically oriented with each other. Further, a beam coinciding means, such as a micro dichroic prism, a micro dichroic plate, a micro dichroic beam-splitter, or an external dichroic beam-splitter, is used to make the two respective laser beams from the two laser diodes to propagate on the same propagation axis when in use.