US 9,812,840 B2  
System for phasing a large number of laser sources  
Jérôme Bourderionnet, Palaiseau (FR); and Arnaud Brignon, Palaiseau (FR)  
Assigned to THALES, Courbevoie (FR)  
Appl. No. 15/313,542 

Filed by THALES, Courbevoie (FR)  
PCT Filed May 26, 2015, PCT No. PCT/EP2015/061524 § 371(c)(1), (2) Date Nov. 22, 2016, PCT Pub. No. WO2015/181130, PCT Pub. Date Dec. 3, 2015. 

Claims priority of application No. 14 01222 (FR), filed on May 28, 2014.  
Prior Publication US 2017/0201063 A1, Jul. 13, 2017  
Int. Cl. H01S 3/13 (2006.01); H01S 3/10 (2006.01); H01S 3/102 (2006.01); H01S 3/08 (2006.01) 
CPC H01S 3/1307 (2013.01) [H01S 3/08009 (2013.01); H01S 3/1024 (2013.01); H01S 3/10053 (2013.01); H01S 3/1305 (2013.01)]  7 Claims 
1. A system for phasing M laser sources of the same wavelength centered around λ_{0}, having a periodic spatial configuration, M being an integer >2, which comprises:
means for collimating and directing the M beams arising from the sources onto a combining diffractive optical element with
a periodic phase grating, with an angle of incidence θ_{2k }that differs from one beam to the next, these angles of incidence being determined according to the period of the grating;
and
means for controlling the phases of said sources based on a negative feedback signal arising from the combined beams;
means for drawing off a fraction of the combined beams;
on the path of this fraction of the combined beams, a Fourier lens having an object plane and an image plane, with the combining
diffractive optical element in its object plane;
a matrix of detectors in the image plane of the Fourier lens, capable of detecting intensity distributions of the fraction
of the combined beams;
comprising:
means for calculating the negative feedback signal based on these intensity distributions which comprise means for calculating
the product of the distribution of the intensities detected in the plane of the matrix of detectors through the inverse of
a matrix of size (2M−1)×(2M−1) if M is odd and 2M×2M if M is even, defined by coefficients obtained through developing the
phase of the combining diffractive optical element, taken over one period, into Fourier series.
