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CQT Seminar: Cosmas Mafusire (Mathematical Optics Group, CSIR NLC)

Mr Cosmas Mafusire (Mathematical Optics Group, CSIR National Laser Centre) will speak about "MODELLING AND MEASUREMENT OF OPTICAL ABERRATIONS OF LASER BEAMS PROPAGATING THROUGH RANDOM MEDIA".
When Nov 21, 2011
from 12:00 PM to 01:00 PM
Where Seminar Room
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THE QUANTUM RESEARCH GROUP,

 

Cordially invite you to attend a

 

QUANTUM TECHNOLOGY COLLOQUIUM

 

MODELLING AND MEASUREMENT OF OPTICAL ABERRATIONS OF LASER BEAMS PROPAGATING THROUGH RANDOM MEDIA

 

Presented by

 

MR COSMAS MAFUSIRE

 

Student Employee, Mathematical Optics Group,

CSIR National Laser Centre

 

 

ABSTRACT:

When laser beams propagate through random media, the phase of the filed is altered in      such a way as to reflect the properties of the medium.  The phase alterations or         distortions to the phase are called aberrations.  We used the Zernike formalism to             represent the aberrations.  We present a detailed study of the impact of aberrations on t      he beam quality factor and field curvature.  This has led us to closed formulae for

calculating the beam quality factor (M2) and the mean focal length of an            abberated lens from Zernike aberration coefficients, models which we    verified experimentally using phase-only spatial light modulator to generate   aberrations and a Shack-Hartmann wavefront sensor for measurement.  We            used these formulae to characterise a spinning pipe gas lens (SPGL) and the          flame lens by studying their computational fluid dynamics (CFD) models.           From the density data, we calculated the phase using the Gladstone-Dale l           aw from which we generated the Zernike coefficients and thus M2, focal         length as well as the Strehl ratio generated by these devices.  We then went          on to perform experimental instigation of the lenses verifying the CFD model    in the process.  The last thing we did was study the turbulence generated by the SPGL using classical turbulence models showing that as its rotation         speed and temperature increases, its turbulence became stronger.

 

DATE: 21.11.2011

 

TIME: 12h00

 

VENUE: NITheP Seminar Room, Level 3, H-Block, Westville Campus

 

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