Search

Tunable circular devices made of liquid crystals or other materials, like lenses, axicons, or phase plates, are often constrained by limitations in size, tunability, power, and other parameters. These constraints restrict their use and limit their applicability. In this review, a thorough study of the use of light's orbital angular momentum in the manufacturing of liquid crystal (LC) devices is presented. Twisted light fosters the simultaneous optimization of most critical parameters. Experimental demonstrations of the unmatched performance of tunable LC lenses, axicons, and other elements in parameters such as lens diameter (>1″), power and tunability (>±6 diopters), fill factor (>98%), and time response have been achieved by reversible vortex generation created by azimuthal phase delay. This phase delay can eventually be removed within the optical system so that lens performance is not affected. [ABSTRACT FROM AUTHOR]

Over the last half century, photography has evolved from photochemical reactions induced on a photosensitive film to optoelectronic devices employed in digital image. Video has done the same migration from classical film movies to optoelectronic acquisition and storage. Digital and video cameras share optics with traditional film cameras, but the image recording is realized by an optoelectronic device -a CCD or CMOS sensor- rather than a film. The quantity of digital photo and video images has dramatically increased in the last decade, arising from the ubiquitous cameras of mobile phones. Despite their popularity, condensed tutorial articles on the subject are still scarce. This work intends to contribute to the knowledge of this field with a medium-level short course that is currently being taught in a broader subject (Consumer Photonics) to undergraduate students of Telecommunication Engineers at the Universidad Politécnica de Madrid. The course can be followed by students having a basic background on Physics and specifically on Optics and Semiconductors. The course is divided into two chapters. An introduction to optics of cameras and basic concepts of photography has been considered necessary to follow the second part, which is entirely devoted to optoelectronic sensors. [ABSTRACT FROM AUTHOR]

Copyright of Óptica Pura y Aplicada is the property of Sociedad Espanola de Optica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have investigated the static and dynamic electrooptical effects of adding an alignment layer derived from a chiral liquid crystal having SmC* and N* phases to the standard polymer alignment layer in antiferroelectric liquid crystal cells. Our results show that the added layer reduces the relaxation time of the liquid crystal, the threshold voltage and the dynamic range required to generate a full greyscale. The electrooptical response of materials was tested using a 7 level waveform, and the relaxation was studied using a novel memory test. [ABSTRACT FROM AUTHOR]