Victor Arrizón

Pixelated phase computer holograms for the accurate encoding of scalar complex fields

We discuss a class of phase computer-generated holograms for the encoding of arbitrary scalar complex fields. We describe two holograms of this class that allow high quality reconstruction of the encoded field, even if they are implemented with a low-resolution pixelated phase modulator. In addition, we show that one of these holograms can be appropriately implemented with a phase modulator limited by a reduced phase depth.

Generation of the "perfect" optical vortex using a liquid-crystal spatial light modulator.

We introduce the concept of the perfect optical vortex whose dark hollow radius does not depend on the topological charge. It is shown analytically and experimentally that such a vortex can be approximately generated in the Fourier transforming optical system with a computer-controlled liquid-crystal spatial light modulator.

MULTILEVEL PHASE GRATINGS FOR ARRAY ILLUMINATORS

We describe a variety of multilevel phase structures that can be used to generate Lohmanns array illuminators. We report several experimental verifications of the synthesis of such multilevel phase structures by using simple binary curves in a conventional optical processor.

Accurate encoding of arbitrary complex fields with amplitude-only liquid crystal spatial light modulators

We show that computer generated holograms, implemented with amplitude-only liquid crystal spatial light modulators, allow the synthesis of fully complex fields with high accuracy. Our main discussion considers modified amplitude holograms whose transmittance is obtained by adding an appropriate bias function to the real cosine computer hologram of the encoded signal. We first propose a bias function, given by a soft envelope of the signal modulus, which is appropriate for perfect amplitude modulators. We also consider a second bias term, given by a constant function, which results appropriate for modulators whose amplitude transmittance is coupled with a linear phase modulation. The influence of the finite pixel size of the spatial light modulator is compensated by digital pre-filtering of the encoded complex signal. The performance of the discussed amplitude CGHs is illustrated by means of numerical simulations and the experimental synthesis of high order Bessel beams.

Talbot array illuminator with multilevel phase gratings

Construction of one-dimensional multilevel phase gratings is described that, when illuminated by a coherent plane wave, lead to the formation of amplitude binary gratings with an arbitrary value of the opening ratio. The gratings are proposed as array illuminators that can provide a significantly high compression factor together with a large number of uniformly illuminated points.

Optimum on-axis computer-generated hologram encoded into low-resolution phase-modulation devices.

A computer-generated hologram with minimum spatial complexity is proposed for encoding arbitrary complex transmittance with low-resolution phase-modulation devices. The phase modulation of the proposed hologram is determined such that on-axis reconstruction with high signal-to-noise ratio, optimum reconstruction efficiency, and the largest possible signal bandwidth can be obtained.

Talbot array illuminators with binary phase gratings

We establish that, in six different cases, binary phase gratings can be applied to implement Talbot array illuminators. Three of the six cases are reported for what is to our knowledge the first time.

Complex modulation with a twisted-nematic liquid-crystal spatial light modulator: double-pixel approach.

I modify the double-phase holographic code to implement complex modulation with a transmission twisted-nematic liquid-crystal display. This device is employed in the mostly phase configuration, for which the phase modulation is coupled with a nonconstant amplitude modulation. The modified double-phase code implements arbitrary complex modulation employing the constrained complex modulation of the display.

Irradiance at Fresnel planes of a phase grating

The Wigner distribution function is used to describe general properties of the irradiance distribution at the Fresnel diffraction planes of one-dimensional phase gratings. We report a remarkably simple, analytical expression for the irradiance distribution at one quarter of the Talbot length of any phase grating. As illustrative examples, we consider binary and triangular phase profiles.

Binary phase grating for array generation at 1/16 of Talbot length

We describe and experimentally verify the generation of a Talbot array illuminator at 1/16 of the self-image distance of a binary phase grating with phase step π.