Visible reconstruction by a circular holographic display from digital holograms recorded under infrared illumination

Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.
Optics Letters (Impact Factor: 3.29). 08/2012; 37(15):3120-2. DOI: 10.1364/OL.37.003120
Source: PubMed


A circular holographic display that consists of phase-only spatial light modulators is used to reconstruct images in visible light from digital holograms recorded under infrared (10.6 μm) illumination. The reconstruction yields a holographic digital video display of a three-dimensional ghostlike image of an object floating in space where observers can move and rotate around it.

Download full-text


Available from: Massimiliano Locatelli
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The ability to see behind flames is a key challenge for the industrial field and particularly for the safety field. Development of new technologies to detect live people through smoke and flames in fire scenes is an extremely desirable goal since it can save human lives. The latest technologies, including equipment adopted by fire departments, use infrared bolometers for infrared digital cameras that allow users to see through smoke. However, such detectors are blinded by flame-emitted radiation. Here we show a completely different approach that makes use of lensless digital holography technology in the infrared range for successful imaging through smoke and flames. Notably, we demonstrate that digital holography with a cw laser allows the recording of dynamic human-size targets. In this work, easy detection of live, moving people is achieved through both smoke and flames, thus demonstrating the capability of digital holography at 10.6 μm.
    Full-text · Article · Mar 2013 · Optics Express
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We show that imaging alive people through smoke and flames is possible by Digital Holography at far infrared. This capability is of crucial importance in the security field to provide a new tool for firefighters and first responders in fire accidents. So far, the existing thermographic infrared cameras allows to see people through dense smoke, sensing the radiation emitted by human body. However, these devices are often blinded due to the flame emission, which is collected by the zoom lenses employed for the scope, and the information of the targets beyond the flames is unavoidably lost. On the contrary, lensless Digital Holography at far infrared avoids the typical saturation of the camera detectors returning clear images of targets seen behind veils of smoke and curtains of flames. Moreover, we demonstrate that human-size holograms can be recorded, allowing to move this promising technology outside the lab for safety applications.
    Full-text · Conference Paper · May 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper a new technique to reduce the noise in a reconstructed hologram image is proposed. Unlike all the techniques in the literature, the proposed approach not only takes into account spatial information but also temporal statistics associated with the pixels. This innovative solution enables, at first, the automatic detection of the areas of the image containing the objects (foreground). This way, all the pixels not belonging to any objects are directly cleaned up and the contrast between objects and background is consistently increased. The remaining pixels are then processed with a spatio-temporal filtering which cancels out the effects of speckle noise, while preserving the structural details of the objects. The proposed approach has been compared with other common speckle denoising techniques and it is found to give better both visual and quantitative results.
    Full-text · Article · Jun 2013 · Journal of Display Technology
Show more