We present an experimental confirmation of optical properties of multiplane holograms designed with our novel iterative method. The method allows encoding many input intensity distributions into a single phase-only hologram. The object planes can be placed at variable distances, and their content is fully customizable. The reconstructed three-dimensional (3D) scenes exhibit high contrast and low noise level in all designed image planes. The results of numerical simulations are compared with those of a reconstruction in an optical setup. Holograms for optical reconstructions were manufactured using two methods: photographic and electron beam lithography (EBL). Experimental results achieved with both methods are compared. We present our research on a new class of iterative holograms, containing up to eleven object planes, designed in close distance to each other. The elements exhibit unusual light focusing possibilities and extraordinary imaging properties, thus introducing a number of possible practical applications, which are discussed.
Compared with conventional optical systems, diffractive optical elements are more suitable to transform laser diode beams because they can form more complex wavefronts and better fulfill requirements of miniaturization. However, high numerical aperture needed to collimate the fast axis of edge-emitting laser diodes demands extremely high spatial frequency elements when single DOE is used. That involves complicated design methods based on rigorous diffraction theory and fabricating technology with sub-wavelength resolution and nanometer accuracy. To overcome these difficulties we propose a transmission DOE consisting of elliptical and cylindrical zone plates fabricated onto opposite sides of a substrate. The main advantage of such a solution lies in fact that each of the zone plates has smaller spatial frequency and can be made even as 8-phase-level element with theoretically 95% diffraction efficiency using available microlithographic technology. In result, monolithic
collimating system that allows to compensate astigmatism and to convert an elliptical laser diode light beam to circular one can be achieved with NA higher than 0.5 and efficiency over 80%.
The paper presents abilities of the Light Sword Optical Element (LSOE) for imaging with extended depth of
focus. The LSOE belongs to the class of optical elements focusing incident light into a segment of the optical axis.
The elements of this kind can be used as correctors of some defects of human eye accommodation, especially in a
case of presbyopia. The paper illustrates imaging properties of the LSOE. In particular, the point spread functions
of the LSOE are analysed numerically. Imaging properties of the LSOE are compared with properties of optical
elements being potentially useful for presbyopia correction as axicons, bifocal lens and trifocal lens. The
experimental results illustrating usefulness of the LSOE in a case of presbyopia are given.
A novel iterative method of generating three-plane, phase-only computer-generated holograms is presented. It is based on the iterative Fresnel ping-pong two-plane algorithm. A modification is introduced to extend the method for three planes, i.e., two object planes and a hologram itself. The described method enables the design of low-noise and high-efficiency phase-only holograms using a numerical Fresnel propagation algorithm. The source method is described, followed by the modified algorithm. Numerical simulation results and algorithm parameters are discussed, followed by a discussion of the method limitations.
We present a class of diffractive elements that can be used in medical applications. We describe their physical properties, in particular the point spread functions and modulation transfer functions. Our analyses consist of the detailed numerical simulations. The obtained results correspond to the different setup parameters and confirm usefulness of such structures in medical aspect, especially in presbyopia treatment.
We present the abilities of diffractive elements for imaging with extended depth of focus. The elements of interest belong to the class of diffractive structures focusing incident light into a segment of the optical axis. We describe the imaging properties of the two following elements of this kind: the annular axicon and the light sword optical element (LSOE). In particular, the point spread functions and the modulation transfer functions of axicons and LSOEs are analyzed experimentally and numerically in detail. The obtained results correspond to different defocusing parameters. The performed experiments confirm the usefulness of axicons and LSOEs for imaging with extended depth of focus.
The paper describes the optical properties of the selected diffractive elements being promising for imaging with extended depth of focus. According to the results of our previous investigations, diffractive versions of the axicon and the light sword optical element were chosen for an analysis. Particularly we have examined the point spread functions of the above elements. The investigated optical properties of the selected diffractive structures were compared with the analogous properties of the conventional Fresnel lens. The results of the numerical simulations were verified experimentally in the optical set-up.