Holographic scanning
First Claim
Patent Images
1. An apparatus for tracing scan lines across a target, said apparatus comprising:
- a source of coherent radiation positioned to deliver a beam along a beam path; and
a diffraction grating element positioned along said beam path so that a portion of said element receives said beam and produces a diffracted beam,said element being mounted for rotation about an axis of rotation so that the portion receiving said beam varies with rotation, andsaid element having a diffraction grating pattern configured so that, as said element rotates, said diffracted beam traces a scan line across said target,wherein said grating element comprises a pattern of grating lines, and the spacing between adjacent grating lines varies along the extent of the grating lines so that said spacing in the portion of said element receiving said beam varies with the angle of rotation of said element, so that the path traced across said target by said scan line is straighter than the path that would be traced by a scan line produced by a diffraction element with fixed spacing between adjacent grating lines.
1 Assignment
0 Petitions
Accused Products
Abstract
A holographic grating element is provided which enables tracing different scan lines. The element is divided into a plurality of sectors. A first grating pattern is provided which diffracts a beam in one direction, and a second grating pattern is next to the first and diffracts the scan beam in the reverse direction. Sectors can be produced with different sector sizes to enable scanning at different rates in the reverse direction, or in successive scans in the same direction. Angle relationships are described to produce diffraction patterns for a desired relationship between disc rotation and the angle of the scan line.
65 Citations
11 Claims
-
1. An apparatus for tracing scan lines across a target, said apparatus comprising:
-
a source of coherent radiation positioned to deliver a beam along a beam path; and a diffraction grating element positioned along said beam path so that a portion of said element receives said beam and produces a diffracted beam, said element being mounted for rotation about an axis of rotation so that the portion receiving said beam varies with rotation, and said element having a diffraction grating pattern configured so that, as said element rotates, said diffracted beam traces a scan line across said target, wherein said grating element comprises a pattern of grating lines, and the spacing between adjacent grating lines varies along the extent of the grating lines so that said spacing in the portion of said element receiving said beam varies with the angle of rotation of said element, so that the path traced across said target by said scan line is straighter than the path that would be traced by a scan line produced by a diffraction element with fixed spacing between adjacent grating lines. - View Dependent Claims (2, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
3. An apparatus for scanning a bar code symbol, said apparatus comprising:
-
a laser beam source positioned to deliver a beam along a beam path; and a diffraction grating element positioned along said beam path so that a portion of said element receives said beam and produces a diffracted beam, said element being mounted for rotation about an axis of rotation so that the portion receiving said beam varies with rotation, and said element having a diffraction grating pattern configured so that, as said element rotates, said diffracted beam traces a scan line across said bar code symbol, wherein said grating element comprises a pattern of grating lines, and the spacing between adjacent grating lines varies along the extent of the grating lines so that said spacing in the portion of said element receiving said beam varies with the angle of rotation of said element, so that the path traced across said target by said scan line is straighter than the path that would be traced by a scan line produced by a diffraction element with fixed spacing between adjacent grating lines.
-
Specification