Proceedings Article | 21 October 2011
KEYWORDS: Beam shaping, Apodization, Point spread functions, Imaging systems, Fourier transforms, Spectrum analysis, Diffraction, Optical imaging, Acousto-optics, Beam analyzers
The Fourier transform optical systems, creating an image and/or realizing its accurate spectral characterization, suffer
from appearing remarkable level of side-lobes in the image intensity distribution that reduce performances, in particular,
the dynamic range of these systems. Therefore, suppressing side-lobes in the image plane represents an actual practical
task being important for various scientific and technical applications such as, for example, direct imaging and spectral
characterization of Earth-like extra-solar planets or spectrum analysis of ultra-high frequency radio-wave signals with
exploiting an advanced acousto-optical technique. We suggest applying as apodization systems novel refractive optical
beam shapers of the field mapping type, which are able to convert the input (more or less) uniform intensity distribution,
peculiar to the majority of usually exploited sources of light, to arbitrary pre-scripted intensity distributions. In the case
of choosing, for instance, Gaussian, cosine on a pedestal, etc. distributions, these shapers make it possible to minimize
the total level of side-lobes significantly and to increase, in doing so, the dynamic range of optical data processing up to
40 dB or more. The operation principle of these beam shapers is based on inducing, in a control manner, spherical
aberration in order to provide the required intensity profile transformation and further compensation of that aberration.
As a result, the beam shapers operate as telescopes of special type; they produce a low divergence collimated beam with
a target intensity distribution and flat wave front. We describe the beam shaper design, implementation examples, and
results of practical applications to the acousto-optical technique of precise multi-channel spectrum analysis.
