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Brotherton-Ratcliffe D.,Glyndwr University | Brotherton-Ratcliffe D.,United Technologies | Brotherton-Ratcliffe D.,Geola Digital uab | Bjelkhagen H.,Glyndwr University | And 2 more authors.
Applied Optics | Year: 2015

The PSM model is used to analyze the process of diffraction occurring in volume reflection gratings in which fringe contrast is an arbitrary function of distance within the grating. General analytic expressions for diffraction efficiency at Bragg resonance are obtained for unslanted panchromatic lossless reflection gratings at oblique incidence. These formulas are then checked for several diverse fringe contrast profiles with numerical solutions of the Helmholtz equation, where exceptionally good agreement is observed. Away from Bragg resonance, the case of the hyperbolically decaying fringe contrast profile is shown to lead to an analytic expression for the diffraction efficiency and this is again compared successfully with numerical solutions of the Helmholtz equation. © 2015 Optical Society of America. Source


Zacharovas S.,Geola Digital uab | Nikolskij A.,Geola Digital uab | Bakanas R.,Geola Digital uab | Bakanas R.,Kaunas University of Technology | Brotherton-Ratcliffe D.,United Technologies
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The Direct Write Digital Holography (DWDH) technique has been used to print master-original holograms for embossed applications using a 440nm pulsed laser. Holograms were recorded on both Silver Halide photo-plates and Shipley photoresist photo-plates. Shipley photoresist consistently exhibited a sensitivity to pulsed radiation several times better than that observed on exposure to CW radiation. In addition, image quality of the recorded holograms using pulsed radiation appeared very similar to that obtainable with CW exposure. The clear implication is that pulsed lasers emitting at 440nm can replace the CW HeCd lasers currently used for the origination of embossed holograms. Master-original holograms recorded with the DWDH technique are able to record deep 3D imagery. The origination technique described allows the production of master-original holograms with achromatic or full colour images. In addition the DWDH technique allows one to combine achromatic and full colour images on one hologram. As a proof of concept, embossing matrix shims were produced from our master-original holograms and embossed holograms were stamped. © 2013 SPIE. Source


Zacharovas S.,Geola Digital uab | Bakanas R.,Geola Digital uab | Bakanas R.,Kaunas University of Technology | Stankauskas A.,Geola Digital uab
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

It is well known fact that holograms can be recorded either by continuous wave (CW) laser, or by single pulse coming from pulsed laser. However, multi-pulse or multiple-exposure holograms were used only in interferometry as well as for information storage. We have used Geola's single longitudinal mode pulsed RGB laser to record Denisyuk type holograms. We successfully recorded objects situated at the distance of more than 30cm, employing the multi-pulse working regime of the laser. To record Denisyuk hologram we have used 50 ns duration 440, 660nm wavelength and 35ns duration 532nm wavelength laser pulses at the repetition rate of 30Hz. As photosensitive medium we have used Slavich-Geola PFG-03C glass photoplate. Radiations with different wavelengths were mixed into "white" beam, collimated and directed onto the photoplate. For further objects illumination an additional flat silver coated mirror was used. © 2016 SPIE. Source


Bakanas R.,Geola Digital uab | Pileckas J.,Geola Digital uab
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

We report on creation of frequency doubled E-O Q-switched Nd:YAG laser lasing Single Longitudinal and Transversal mode radiation at 1319 nm ( 4F3/2 to 4I11/2 transition) at repetition rate of 10 Hz. By means of linear resonator stable redlight pulses were obtained at 660 nm having Emax = 5mJ output energy and τ = 50 ns (FWHM) pulse duration by using NCPM LBO crystal as an extra-cavity frequency doubler. Laser design incorporates particularly made fast negative feedback loop controls for pulse buildup control. It allowed obtaining much more stable laser performance as well as much shorter Optical Jitter and fast pulse buildup time. To best our knowledge, these are the first time such pulse energy, rep rate Transversal and Longitudinal mode structure ever achieved in compact flashlamp pumped E-O Q-Switched laser operating at 1319 nm. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source


Zacharovas S.J.,Geola Digital uab | Zacharovas S.J.,Kaunas University of Technology | Bakanas R.,Geola Digital uab | Bakanas R.,Kaunas University of Technology | And 3 more authors.
Optical Engineering | Year: 2014

Direct write digital holography technique (DWDH) using a single 440-nm pulsed laser exposure has been proposed to record master holograms on commercially available positive-tone photoresist systems based on a mixture of diazonaphthoquinone and novolac resin (DNQ-novolac) of different thicknesses. The DNQ-novolac nanocomposite doped with copper nanoparticles (CuNPs) films was also used. The method for numerical evaluation of hologram quality based on reflected beam diffraction intensity measurements was proposed and verified. It was found that all investigated photoresist nanocomposites were sensitive enough to record holographic structures at low single pulse laser exposures (from 3.3 to 18.0 mJ/cm2). Moreover, doping DNQ-novolac nanocomposite with CuNPs s increases its sensitivity to pulsed laser exposure by more than 30%. The potential of single pulsed laser exposures to record high quality master holograms on commercially available and metal nanoparticles doped photoresists with at least five times lower exposures values as compared to the continuous-wave laser exposures usually used to expose photoresist materials in holographic applications, opens the possibility to use pulsed lasers for quick master-originals origination for embossed holograms applying a DWDH technique or analog methods. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE). Source

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