Planar optical scanning head having deficiency-correcting grating
AssigneeU.S. Philips Corporation
InventorWillem G. Opheij
Life of this patent
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Abstract
A planar optical head is described with a corrected input grating for scanning a surface, for example, a recording surface (2) in an optical record carrier (1). A radiation source (5) supplies a beam (6) which is coupled into a waveguide (9) by an input grating (7) and is formed to a focused scanning beam (11) by an output grating (10). Deficiencies of the radiation beam such as the non-round cross-section of the beam, astigmatism and wavelength variations caused by the radiation source can be corrected by means of an adapted grating structure of the input grating.
Claims17
An optical head for scanning a surface, which head is provided with a source supplying a radiation beam, an input grating having a periodic grating structure for coupling the radiation beam as a deflected beam into a waveguide, and an output grating for coupling radiation out of the waveguide and for directing said radiation in the form of a scanning beam onto the surface, characterized in that the input grating is configured to provide at least one correction for a deficiency of the radiation beam.
An optical head for scanning a surface, comprising means for providing a radiation beam, a waveguide, an input grating having a periodic structure for coupling said radiation beam into said waveguide, and an output grating fro coupling radiation out of the waveguide and for directing said radiation as a scanning beam toward said surface,
- characterized in that said grating structure deviates from a completely symmetrical circular grating structure, the deviation from complete circular symmetry correcting at least one deficiency of said radiation beam.
Dependencies are inferred from the claim text.