Method and system for generating a high laser power
AssigneesCompagnie Industrielle Des Lasers Cilas, Centre National de la Recherche Scientifique (CNRS), Universite De Limoges
InventorsVincent KERMENE, Agnes DESFARGES-BERTHELEMOT, Paul ARMAND, Joel BENOIST, David KABEYA, Alain BARTHELEMY, David SABOURDY, Jean-Eucher MONTAGNE
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Abstract
According to the invention, a plurality of elementary laser beams (fi) are generated, the phases of which are adjusted by an electro-optical feedback loop (6, 7i, 8i, 9) implementing the matrix equation of a phase-contrast filtering device (6).
Claims11
Method for generating a high laser power by means of a plurality of elementary laser beams (fi) having the same frequencies but having different phases, a method according to which:
- the relative phase (φi) of each of said elementary laser beams (fi) is transformed into a light-intensity level (ΔIi) by a phase-contrast filtering applying a function matrix equation M;
- the light-intensity level (ΔIi) thus obtained for each of said elementary laser beams (fi) is transformed into a phase-correction value (−φ′i);
- and
- said phase-correction values (−φ′i) are respectively applied to the elementary laser beams (fi),
- characterised in that:
- a) laser beam portions (pi) are taken respectively from said elementary laser beams (fi), said laser beam portions (pi) constituting complex optical fields (Ai) that have respectively the same relative phase (φi) as the elementary laser beams (fi) from which they originate and wherein the set A that they form is subjected to phase-contrast filtering according to the matrix equation B=M·A in order to form a set B of filtered complex optical fields (Bi) corresponding to the filtered portions of the laser beam portions (pi);
- b) the intensities (ai) of the complex fields (Ai) formed by said laser beam portions (pi) are determined before filtering;
- c) the intensities (bi) of the complex fields (Bi) formed by said laser beam portions (pi) are determined after filtering;
- d) the ideal case is considered where all the relative phases (φi) of the elementary laser beams (fi) are identical and where the complex set A becomes a pure real set Aideal solely formed from the intensities (ai) determined at step b) and the corresponding filtered set Bideal is calculated by means of the matrix equation Bideal=M·Aideal, in order to determine the corresponding phases (θi) of the filtered complex fields in this ideal case;
- e) the phases (θi) calculated at step d) are attributed to the filtered complex fields (Bi) in order to form a theoretical filtered set Bt and a theoretical set At is calculated before corresponding filtering by the inverse matrix equation At=M−1.Bt, in order to determine the phases (φ′i) of the complex optical fields constituting this theoretical set At before filtering;
- and
- f) the sign of said phases (φ′i) of the theoretical set At is reversed and these reversed-sign phases (−φ′i) are used as phase-correction values.
System for generating a high laser power by means of a plurality of elementary beams fi having the same frequencies, but having different phases, this system comprising:
- a phase-contrast filtering device (6) transforming, in accordance with a matrix equation M, the relative phases (φi) of said elementary beams into light-intensity levels (ΔIi);
- means (9) for transforming said light-intensity levels (ΔIi) into phase-correction values (−φ′i);
- and
- phase modulators (10.i) for applying said phase-correction values (−φ′i) to said elementary laser beams (fi),
- characterised:
- in that it comprises beam-division means (4.i) for taking laser beam portions (pi) from said elementary laser beams (fi);
- in that the phase-contrast filtering device (6) is placed on the path of said laser beam portions (pi);
- in that it comprises detection means (7.i and 8.i) for detecting the intensity of said laser beam portions (pi) respectively upstream and downstream of said phase-contrast filtering device (6);
- and
- in that it comprises computing means (9) connected to said detection means (7.i and 8.i), computing the phases ((p′i) of the complex optical fields constituting a theoretical set At before filtering and by reversing the sign thereof, and applying the reversed-sign phases (−φ′i) as phase-correction values to said phase modulators (10.i).
Dependencies are inferred from the claim text.