Beamshaper for optical head
View Patent ↗An optical head of a type useable in a optical disk reader/writer is provided. One of the optical elements is provided in a fashion that one or more optical parameters or characteristics of the system are invariant, regardless of whether the one optical element is used, or not. In one embodiment the optical element is a beamshaper. In order to provide the desired invariant property, the surfaces of the optical element are preferably formed with high accuracy. One manner of economically achieving high accuracy is to measure errors or imperfections in a first formed, preferably etched, surface and adjust the shape or position of a second aligned etched surface so as to at least partially compensate for the errors or imperfections.
1. A method for providing an optical head in a read/write device comprising:
positioning a light source with respect to an optical head substrate;
positioning at least a first optical element along an optical path from said light source to an objective, said optical path defines at least a farthest virtual source point; and
providing at least a first beamshaper in said optical path wherein a farthest virtual source point of said optical pat after said first beamshaper is provided is substantially the same as said farthest virtual source point before said first beamshaper is provided, and wherein the beamshaper changes an ellipticity of a light beam transmitted by the light source along the optical path.
2. A method as claimed in claim 1 wherein said beamshaper and said first optical element are positioned on a single integral optical element unit.
3. A method, as claimed in claim 1 wherein said first optical element is a non-beamshaper element.
4. Optical head apparatus for use in a read/write device comprising:
an optical head substrate;
a light source positioned with respect to said optical head substrate;
a first optical element positioned along an optical path from said light source to an objective; and
a beamshaper in said optical path, wherein a farthest virtual source point of said optical path after said beamshaper is positioned in the optical path is substantially the same as said farthest virtual source point before said beamshaper is positioned in the optical path, and wherein the beamshaper changes an ellipticity of a light beam transmitted by the light source along the optical path.
5. Apparatus as claimed in claim 4 wherein said beamshaper and said first optical element are positioned on a single integral optical element unit.
6. Apparatus, as claimed in claim 4 wherein said first optical element is a non-beamshaper element.