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| What is claimed is: 1. A polarizing plate comprising: a protective film, 5 to 150 μm thick, ... |
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| Polarization independent wavelength tunable filter based on birefringence compensation |
| It is an object of the present invention to provide a tunable, polarization independent wavelength ... |
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| Wavelength division multiplexer and demultiplexer |
| This invention is based on the observation that many filters have the characteristic property that ... |
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| Tunable filtering device for optical communications |
| To solve the above problems, it is an objective of the present invention to provide a tunable ... |
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| Wavelength selection switches for optical application |
| This invention is based on the observation that, by making use of filters that selectively passes ... |
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| All-optical holographic code division multiple access switch |
| These shortcomings and other limitations and deficiencies are obviated in accordance with the ... |
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| Method and apparatus for displaying three-dimensional images |
| What is claimed is: 1. A method for producing a three-dimensional image, comprising the steps of: ... |
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| Lens array and method of making same |
| FIG. 4 is a flowchart illustrating a method 400 in accordance with an embodiment of the present ... |
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Light beam shaping device to change an anisotropic beam to an isotropic beam for reducing the size of an optical head
| Details |
Inventors: Hoshino, Isao; Wachi, Shoko; Honguh, Yoshinori; Tanaka, Masahiko;
Assignee: Kabushiki Kaisha Toshiba (Kawasaki, JP)
Primary Examiner: Epps; Georgia Y.
Assistant Examiner: Chu; Kim-Kwok
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
An optical head device adapted to be optically coupled to an optical disk includes a light-source laser and an objective lens optically coupled thereto. This lens receives an output light of the light source, and causes it to be projected onto the optical disk to form a focused spot thereon. Photodetectors which are arranged near the light-source laser are optically coupled to the lens in one optical path so that they are responsive to a light component which is reflected from the optical disk toward the photodetectors by way of the objective lens. A beam-shaping prism is located between the lens and a group of the light source and the photodetectors in the optical path. When the laser output light travels toward the lens, the prism reshapes the light into a predetermined isotropic beam profile. When the reflected light from the optical disk propagates reversely along the same optical path to enter the beam-shaping prism, this prism permits such an incident light to pass through itself toward the photodetectors. |
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DETAILED DESCRIPTION It is therefore an object of the present invention to provide a new and improved optical head device for use in an optical record and read/write apparatus.
It is another object of the invention to provide a new and improved optical record and read/write apparatus employing a size-decreased optical head device for selectively providing a write beam and a read beam different in power from each other.
It is a further object of the invention to provide a new and improved optical record and read/write apparatus employing a small-sized optical head device for selectively providing a round disk-shaped record carrier body with a write beam and a read beam different in power from each other.
The above objects can be attained by a first optical head device adapted to be optically coupled to an information record carrier body.
The first optical head device comprises a light source for emitting a light beam having an anisotropic beam shape in a predetermined direction of an optical axis; a photodetector, provided on a surface perpendicular to the optical axis of the light source to be close to the light source, for detecting a change of a beam diameter in a predetermined direction; an objective lens, provided close to the information record carrier body, for converging spot light to the information record carrier body and receiving reflected light from the information record carrier body; collimating means, provided among the light source, the photodetector, and the objective lens, having at least a function of converting a light beam having an anisotropic beam shape to substantially a flux of parallel light; and beam shaping means, provided between the collimating means and the objective means, for at least approximating a characteristic of the light beam having an anisotropic beam shape to a characteristic of the light beam having an isotropic beam shape.
Also, the above objects can be attained by a second optical head device adapted to be optically coupled to an information record carrier body
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Optical Systems 
