Three-wave Lateral Shearing Interferometer Research Articles

Beam-focus shaping by use of programmable phase-only filters: application to an ultralong focal line

We have developed a high-resolution programmable adaptive-optic device based on an optically addressed liquid-crystal electro-optic valve controlled by an achromatic three-wave lateral shearing interferometer. We apply this phase-only filter and loop to shape the far-field pattern of laser beams. As a first application, we theoretically compute and experimentally verify the focus along a line longer than tens of Rayleigh ranges.

Measurements of small wave-front distortions using a three-wave lateral shearing interferometer

The solution of the parabolic equation for radiation diffracted from a periodic hexagonal structure is analysed theoretically. It is shown that diffraction does not prevent high-precision measurements of wave-front distortions using a three-beam lateral shearing interferometer. The proposed measuring technique is based on the recording of interference-pattern distortions at arbitrary distances from a beam replicator. The results of numerical calculations supporting this technique are presented. The optical quality of an etalon plate is measured in an aperture of diameter 12 cm with a high degree of precision. By considering the example of a large-aperture KDP crystal, it is shown that the application of this method makes it possible to synthesise from individual measurements the wave front in an aperture considerably larger than the test beam aperture.

Phase conjugation of broadband light at three-wave mixing in a nonlinear crystal

Experimental and simulation results of work aimed to obtain a conjugate wave of broadband light are shown. Phase conjugation (PC) at three-wave mixing is used for this purpose. A broadband (δ λ∼10 Å) signal wave of the first harmonic and single-frequency pump wave of the second harmonic which has quasi-flat wavefront are mixed in DKDP crystal. To measure wavefronts of mixing waves an achromatic three-wave lateral shearing interferometer is used. It is shown that an emerging broadband idler wave has the wavefront complex conjugated to the one of the signal wave. The quality of PC is determined by the flatness of the pump wave.

A method for measuring the radiation wave front by using a three-wave lateral shearing interferometer

An analysis of and some corrections to the technique of phase distribution measurement by means of a three-wave lateral shearing interferometer are made. The technique offers high precision and a wide dynamical range; it is also rather simple and handy when applied to various fields. The device for the wave front reconstruction and the data-processing algorithm is described. The results of the model simulation of the wave front meter as well as the experimental results are presented.

Wave-front correction of femtosecond terawatt lasers by deformable mirrors

Wave-front correction and focal spot improvement of femtosecond laser beams have been achieved, for the first time to our knowledge, with a deformable mirror with an on-line single-shot three-wave lateral shearing interferometer diagnostic. Wave-front distortions of a 100-fs laser that are due to third-order nonlinear effects have been compensated for. This technique, which permits correction in a straightforward process that requires no feedback loop, is also used on a 10-TW Ti:sapphire-Nd:phosphate glass laser in the subpicosecond regime. We also demonstrate that having a focal spot close to the diffraction limit does not constitute a good criterion for the quality of the laser in terms of peak intensity.

Wavefront sensor prototype for industrial applications based on a three-level phase grating

The wavefront sensor is a key component in applications such as adaptive optics, atmospheric turbulence analysis, and flow visualization. A prototype achromatic three-wave lateral-shearing interferometer is described. It is adapted to low-light-level conditions and enables high spatial resolution of the analyzed wavefront. It is essentially based on the use of a specific three-level phase grating.

Achromatic three-wave (or more) lateral shearing interferometer

A new kind of lateral shearing interferometer, called the three-wave lateral shearing interferometer, was previously described [ Appl. Opt.32, 6242 ( 1993)]. As this instrument was monochromatic and its usable light efficiency was poor, the proposed setup was well suited only for a class of wave-front sensing problems, such as optical testing, in which the source can be easily adapted. A new achromatic setup adapted to low light level applications is presented. Three replicas of the analyzed wave front are obtained by Fourier filtering of the orders diffracted by a microlens array. An important feature of these new devices is their great similarity to another class of wave-front sensors based on the Hartmann test.

Three-wave lateral shearing interferometer

The three-wave lateral shearing interferometer is an interferometer specially designed for optical testing. It determines three noncollinear phase gradients from one single-fringe pattern. From these quantities, two orthogonal derivatives and the measurement error are estimated, allowing the reconstruction of the aberrated wave front. This new interferometer has several benefits; among them is that its sensitivity and dynamics can be easily adjusted to the analyzed aberrations.