Fringe visibility enhancement arrangement and method
AssigneeUnited Technologies Corporation
InventorJames P. Waters
Life of this patent
Estimating the term…
Abstract
An arrangement for smoothing a coherent laser beam of a limited yet substantial coherence length due to the presence of several discrete optical frequencies therein is operative for subdividing the coherent laser beam into a plurality of partial beams of substantially the same intensity. Each of the partial beams is then conducted in a different path, the length of at least one of which differs from that of another path by a distance amounting to a fraction of the coherence length. At least some of the partial beams are subsequently combined into a coherent output beam in which the partial beam issued from the one path is shifted by the distance relative to that issued from the other path.
Claims20
An arrangement for smoothing a coherent laser beam of a limited yet substantial coherence length due to the presence of several discrete optical frequencies therein, comprising
- means for subdividing the coherent laser beam into a plurality of partial beams of substantially the same intensity;
- means for conducting each of said partial beams in a different path, the length of at least one of said paths differing from that of another by a distance amounting to a fraction of said coherence length;
- and
- means for combining at least some of said partial beams after passage thereof through said conducting means into a coherent output beam in which the partial beam issued from said one path is shifted by said distance relative to that issued from said other path.
An interferometric arrangement comprising
- means for forming a coherent laser beam of a limited yet substantial coherence length due to the presence of several discrete optical frequencies therein;
- comprising
- means for splitting the coherent laser beam into two substantially equal laser beam portions;
- means for guiding each of said laser beam portions in a different trajectory;
- means for joining said laser beam portions downstream of said guiding means for interference with one another;
- and
- means for enhancing the interference fringe visibility, including
- means for subdividing one of said laser beam portions propagating in one of said guiding means into a plurality of partial beams of substantially the same intensity,
- means for conducting each of said partial beams in a different path, the length of at least one of said paths differing from that of another by a distance amounting to a fraction of said coherence length, and
- means for combining at least some of said partial beams after passage thereof through said conducting means into a coherent output beam in which the partial beam issued from said one path is shifted by said distance relative to that issued from said other path.
A method of smoothing a coherent laser beam of a limited yet substantial coherence length due to the presence of several discrete optical frequencies therein, comprising
- subdividing the coherent laser beam into a plurality of partial beams of substantially the same intensity;
- conducting each of the partial beams in a different path, the length of at least one of the paths differing from that of another by a distance amounting to a fraction of said coherence length;
- and
- subsequently combining at least some of the partial beams with one another to form a coherent output beam in which the partial beam issued from said one path is shifted by said distance relative to that issued from said other path.
Dependencies are inferred from the claim text.