Optical: systems and elements – Lens – Single component with multiple elements
Reexamination Certificate
2001-04-26
2004-11-30
Schwartz, Jordan M. (Department: 2873)
Optical: systems and elements
Lens
Single component with multiple elements
C359S665000, C359S741000
Reexamination Certificate
active
06825995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device, an optical system a method of production of the optical device, and a mold for production of the optical device.
2. Description of the Related Art
When producing a lens, the following first to third methods of production have been known.
The first method of production is a method of filling an optical material such as molten glass in a metallic mold formed with a cavity of a desired lens shape machined to an intended lens shape to produce a mold lens.
The second method of production is a method of utilizing reactive ion etching (RIE) or other etching and using a photo resist or the like as a mask (etching mask) to etch an optical material to a predetermined shape to thereby produce a lens made of the related optical material.
The third method of production is a method of mechanically polishing a base made of an optical material to the lens shape to produce the lens.
In the conventional first method of production, that is, the method using simple molding, it is difficult to produce a small sized lens having a large numerical aperture (NA), so it is difficult to reduce the lens diameter to 1 mm or less.
In the conventional second method of production, that is, the method using RIE or other etching, there is a problem in that there are restrictions on the optical material and there are a few optical materials of high refractive indexes capable of obtaining lenses having large numerical apertures among the optical materials capable of RIE and other etching, so it is difficult to use a material having a high refractive index and it is difficult to realize a lens having a large numerical aperture NA.
In the conventional third method of production, it is difficult to manufacture a small sized lens.
If increasing the numerical aperture of the lens, it is possible to make the size of a light spot created after passing through the lens small. It is desirable from the viewpoint of increase of the capacity of an optical disc to enlarge the numerical aperture NA of the lens (object lens) of an optical head.
Also, lenses and other optical devices are being used for various optical apparatuses. Reduction of the size of the optical devices is desirable from the viewpoint of the reduction of size of the optical apparatuses such as an optical disc apparatus and an optical pickup.
In order to realize an optical device having a large numerical aperture, a large refractive index of the optical material is effective.
As an optical material having a high refractive index in a region of visible light, there are titanium oxide, tantalum oxide, gallium phosphate (gallium phosphorus), gallium nitride, silicon nitride, etc.
However, it is difficult to machine these materials to small sized lenses having a large numerical aperture in the prior art.
Also, many conventional lenses have irregular shapes. In order to align a plurality of lenses of such irregular shapes, high precision positioning in three-dimensional directions is necessary, so the load of the alignment work is large.
Also, when comprising a flying head (floating head) consisting of an optical head mounted on a swing arm, the optical head can be prepared by separately preparing a slider and the lens and attaching them at a high precision, but in this case, the load of the attachment work and accordingly the load of preparation of the optical head is large.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical device having a small size, or a small size and a large numerical aperture.
Another object of the present invention is to provide an optical system comprising the optical device, that is the optical device having a small size, or a small size and a large numerical aperture. Still another object of the present invention is to provide a method of production of an optical device for producing such optical device, that is the optical device having a small size, or a small size and a large numerical aperture.
Further, still another object of the present invention is to provide a mold for production of an optical device for using in such method of the optical device.
According to a first aspect of the present invention, there is provided an optical device comprising a first optical portion made of a first optical material and having a concavity; and a second optical portion comprising a second optical material having a refractive index different from that of the first optical material, and inserted into the concavity.
According to a second aspect of the present invention, there is provided a method of production of an optical device comprising a first optical portion made of a first optical material and having a concavity and a second optical portion comprising a second optical material having a refractive index different from that of the first optical material, and inserted into the concavity, including: a step of injecting the first optical material into a metallic mold formed with a projection projecting out into a cavity to form the first optical portion made of the first optical material with a concavity reproducing the shape of the projection; and a step of filling the second optical portion in the concavity of the molded.
According to a third aspect of the present invention, there is provided a method of production of an optical device comprising a first optical portion made of a first optical material and having a concavity and a second optical portion comprising a second optical material having a refractive index different from that of the first optical material, and inserted into the concavity, including: a step of forming a resist having a hole in the flat surface of the first optical portion made of the first optical material; a step of forming a concavity corresponding to the hole in the first optical portion by etching; a step of removing a resist from the first optical portion with the concavity formed therein; and a step of filling the second optical portion in the concavity of the first optical portion from which the resist is removed.
According to a fourth aspect of the present invention, there is provided a method of production of an optical device comprising a first optical portion made of a first optical material and having a concavity and a second optical portion comprising a second optical material having a refractive index different from that of the first optical material, and inserted into the concavity, including: a step of forming on a third optical portion provided with a projection and having a flat area around the projection the first optical portion made of a layer of the first optical material burying the projection, a step of flattening the surface of the first optical portion to form a flat surface and bonding the related flat surface to a third base material made of a third optical material, a step of removing the third optical portion from the first optical portion bonded to the third base material to expose the concavity reproducing the shape of the projection in the first optical portion, and a step of filling the second optical portion in the concavity of the exposed first optical portion.
According to a fifth aspect of the present invention, there is provided a method for production of an optical device wherein a second optical portion having a refractive index different from a first optical material is filled in a concavity of a first optical portion made of the first optical material, comprising: a step of forming resist films having windows on substantially flat first and second flat surfaces facing each other of a first optical portion made of the first optical material; a step of forming concavities corresponding to the windows in the first and second flat surfaces of the first optical portion by etching; a step of removing the resist films from the first optical portion with the concavities formed therein; and a step of filling the second optical portion in the concavities of the first and second flat surfaces of the first optical portion from which the resist fi
Kouchiyama Akira
Watanabe Tetsu
Yamada Masahiro
Kananen Ronald P.
Rader & Fishman & Grauer, PLLC
Schwartz Jordan M.
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