Terahertz diffractive structures for compact in-reflection inspection setup.

Two diffractive optical elements are used to create a compact raster THz scanning setup in reflective configuration. The first one focuses the radiation into the small focal spot on the sample, while the second one collects reflected radiation and focuses it on the detector. To assure small size of the setup and large apertures of optical elements, structures work in the off-axis geometry.

Miniature holographic projector with cloud computing capability.

A fully functional miniaturized projection head below 5   is presented, using computer-generated holograms dynamically displayed on a liquid-crystal spatial light modulator. Spatial division of the modulator is used for color projection without color breakup, and specially designed, anti-reflection coated prisms ensure simple light paths with small losses. Real-time calculations are performed on a remote server with on-the-fly compression of holographic fringes.

Collective matrix of spatial light modulators for increased resolution in holographic image projection.

We present a method to increase the resolution of holographically projected images by the use of a collective matrix of two phase-only spatial light modulators. As a result of fine alignment and common coherent illumination of the modulators, a synthetic aperture is formed with a doubled number of active pixels. In this paper we present theoretical analysis and numerical simulations which stand in good agreement for different distances between the apertures of modulators.

Assessment of imaging with extended depth-of-field by means of the light sword lens in terms of visual acuity scale.

We present outcomes of an imaging experiment using the refractive light sword lens (LSL) as a contact lens in an optical system that serves as a simplified model of the presbyopic eye. The results show that the LSL produces significant improvements in visual acuity of the simplified presbyopic eye model over a wide range of defocus. Therefore, this element can be an interesting alternative for the multifocal contact and intraocular lenses currently used in ophthalmology.

High order kinoforms as a broadband achromatic diffractive optics for terahertz beams.

We discuss thin optical structures that allow chromatic aberrations to be avoided in the THz domain. The paper contains the theoretical considerations, computer modeling and experimental evaluation of the high order kinoform diffractive elements in the THz range. According to the obtained results application of the high order kinoforms enables broadband operation in the THz range.

Surface profilometry with binary axicon-vortex and lens-vortex optical elements.

We report on the interesting effect observed with the diffractive binary element, which matches the property of an axicon and vortex lens. Binary phase coding simplifies the manufacturing process and gives additional advantages for metrology purposes. Under laser beam illumination, our element produces two waves: converging and diverging.

Evaluation of the shadow effect in terahertz kinoform gratings.

The experimental and numerical evaluation of the shadow effect in kinoform diffractive gratings for the terahertz (THz) range is given. This effect limits the diffractive efficiency of dense gratings, which are the base of the elements suited for convenient beam focusing and imaging in THz. The observed effect of redirecting most of the incident energy into stray -1st diffractive order is observed and discussed.

Simple holographic projection in color.

Extremely simplified image projection technique based on optical fibers and a single Spatial Light Modulator is presented. Images are formed by addressing the modulator with especially iterated Fourier holograms, precisely aligned on the projection screen using phase factors of lenses and gratings. Focusing is done electronically with no moving parts.

Modeling of the optical system illuminated by quasi-monochromatic spatially incoherent light: new numerical approach.

This Letter presents a new method for modeling of complex optical setups illuminated by quasi monochromatic spatially incoherent light. The algorithm provides better performance and quality than other modeling methods both for isoplanatic and nonisoplanatic systems. The algorithm maintains energy relations, image orientation, and magnification of the system.

Efficient image projection by Fourier electroholography.

An improved efficient projection of color images is presented. It uses a phase spatial light modulator with three iteratively optimized Fourier holograms displayed simultaneously--each for one primary color. This spatial division instead of time division provides stable images.

Color image projection based on Fourier holograms.

A method of color image projection is experimentally validated. It assumes a simultaneous illumination of a spatial light modulator (SLM) with three laser beams converging in a common point on a projection screen. The beams are masked with amplitude filters so that each one illuminates one third of the area of the SLM.

Experimental evaluation of a full-color compact lensless holographic display.

An iterative phase retrieval method for a lensless color holographic display using a single light modulator is experimentally validated. The technique involves iterative calculation of a three-plane synthetic hologram which is displayed on a SLM simultaneously lit with three laser beams providing an RGB illumination. Static and animated two-dimensional flicker-free full color images are reconstructed at a fixed position and captured using a high resolution CMOS sensor.