Alexis Kudryashov

The real-time atmospheric turbulence modeling and compensation with the use of adaptive optics

It is suggested to reconstruct the phase screens with the use of different deformable mirror types. In this work we present the results of the phase screen reproducing with the use of stacked-actuator deformable mirror and bimorph one. The reconstruction results were compared. The problems of the reconstruction were discussed.

New approaches of uniform focal spot formation by means of deformable mirror

In this paper the results of the flat-top beam formation by means of bimorph deformable mirror are presented. The problems of simulation are discussed. A new method for beam structure modification is suggested.

Wide aperture bimorph mirrors for high-power laser beam control

The deformable mirror with the size of 410×468 mm controlled by the bimorph piezoceramic plates and multilayer piezoceramic stacks was developed. The results of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack-Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm (RMS). The possibility of correction of the aberrations in high power lasers was numerically demonstrated.

Uniform focal spot formation in adaptive system with Shack-Hartmann sensor and M2 sensor

Recent results of formation of uniform beam intensity distribution at the focal plane of a lens by means of bimorph deformable mirrors are presented. An approach based on the use of Shack-Hartmann wavefront sensor together with focal spot sensor (M2 meter) is suggested. Advantages and disadvantages are discussed.

A new method of the real-time atmospheric turbulence modeling

It is suggested to reconstruct the real-time atmospheric turbulence in the lab by means of the stacked-actuator deformable mirror and the bimorph deformable mirror. The characteristics of the spatial reconstruction are discussed. The phase screens interpolation methods are presented. The problems of the reconstruction are shown.

More than 500 mm deformable mirrors for high power laser beam correctio

Deformable mirrors with the size of 410×470 mm for high power lasers was developed. The results of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack-Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm (RMS). The possibility of correction of the aberrations in high power lasers was numerically demonstrated.

Problems of uniform focal spot formation by means of deformable mirror

In this paper we present recent results of formation of different beam intensity distribution by means of bimorph deformable mirrors. We discuss the results of such formation as well as the problems that one faces on this way. A new method for beam structure modification is suggested based on the use of Shack-Hartmann wavefront sensor with the combination of standard M2 meter.

Ion-assisted coating for large-scale Bimorph deformable mirror

We have fabricated a 410 x 468 mm size deformable mirror with 100 Bimorph piezoceramic actuators for the LFEX laser system at Osaka University. In the case of Bimorph-type deformable mirrors, the mirror surface had to be polished and coated after bonding the piezoceramic actuators to the rear side of the thin mirror substrate. This provides a good surface figure, but the coating temperature for the high-reflection mirror was strictly limited because of the thermal fragility of piezoceramic actuators. The mirror substrate with the actuators was polished, and an ion-assisted multilayer dielectric coating was produced at 60 degrees Celsius with our 80-inch coating chamber. The flatness of the mirror just after coating was 7 μm, and reduced by aging to 3.2 μm when the mirror was assembled. The surface figure of the assembled mirror with 20 piezostack bonded actuators is demonstrated and a laser-induced damage threshold tested with a witness sample is also reported.

Laser beam propagation and wavefront correction in turbid media

It is well known that turbid medium such as fog or biological tissues causes light scatter. This phenomenon is known as major impediment for imaging and focusing of light. Thus it is important to understand the impact of the turbid medium on the light characteristics, namely intensity and phase distributions. In this work laser beam propagation through the scattering suspension of polystyrene microspheres in distilled water was investigated both theoretically and experimentally. We obtained the dependence of the wavefront aberrations on the particles concentration and shown the existence of high-order symmetric wavefront aberrations of the laser beam passed through turbid medium. The investigation showed that with the use of bimorph deformable mirror the wavefront aberrations of scattered light could be effectively corrected.

Formation of the desired light intensity distribution on the target with bimorph deformable mirror

It is desired to use some special intensity distribution on the target for various industrial applications. The adjusting of the intensity profile can be implemented by means of adaptive optics. In this paper we present laser beam control in the focal plane of lens with bimorph deformable mirrors. Hill-climbing method and stochastic algorithm are compared. Advantages and disadvantages of two methods are discussed.