Stanislovas Zacharovas

Digital holographic printing using pulsed RGB lasers

A one-step digital holographic printing system based on RGB pulsed-laser technology is described. The system is capable of writing full-color composite digital reflection holograms and composite digital holographic optical elements up to a size of 1.0 m×1.5 m at hogel sizes ranging from 0.4 to 2 mm. We also show how the same pulsed-laser technology may be used to generate fast high-quality copies of such holograms. Both silver halide and photopolymer materials are used.

Recent advances in holographic materials from Slavich

A general review of the current holographic materials available from the Micron Plant at AO Slavich is presented. In particular certain improvements to the technical parameters of the materials PFG-01 and PFG-03M (notably sensitivity) and PFG-03C (diffraction efficiency) are introduced. Likewise the introduction of a new 190 micron TAC film substrate for the PFG-01, PFG-03M, PFG-03C and VRP- M emulsions will be mentioned and examples of holograms produced on these emulsions will be shown. Various reflection hologram color control techniques are briefly discussed. Recommended chemistries that may be employed with each of the Slavich materials will be discussed in the context of Pulsed and CW radiation sources. A new VRP-3 developer recipe suitable for VRP=M will be introduced. Finally, contact copying using the PFG-01 and PFG-03M materials will be briefly mentioned.

Holographic materials available from Geola

A general review of the current holographic materials available from the Geola distribution network is presented. Recommended chemistries for both pulsed and CW-laser recorded Silver Halide holograms are reviewed. Color control techniques for Silver Halide reflection holograms are discussed. Finally new recipes for developers and bleaches are presented.

One-step 3D full colour and achromatic transmission holograms digitally printed using a 440nm pulsed laser for embossed applications

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.

DYI digital holography

We have created a programming tool which uses image data provided by webcam connected to personal computer and gives user an ability to see the future digital hologram preview on his computer screen, before sending video data to holographic printing companies. In order to print digital hologram, one needs to have a sequence of images of the same scene taken from different angles and nowadays web cameras - stand-alone or incorporated into mobile computer, can be an acceptable source of such image sequences. In this article we are describing this DIY holographic imaging process in details.

Holograms recording with pulsed laser on diazonaphthoquinone-novolac-based photoresists and their nanocomposites

Abstract. 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.

Effective public security features for embossed holograms

New combined embossed hologram originating technique was developed by the international team of holography experts. The technique merges deep 3D holographic images with commonly used hologram security features. Deep 3D images were first recorded on photoresist with Geolas holographic printer containing their proprietary pulsed laser. Optical security features were then overexposed onto the photoresist plates containing latent images of deep 3D scenes. The photoresist plates with several exposures (containing optical security features and deep 3D images) were developed. Embossed holograms, containing such effective public security features as full colour 3D images, guilloches, rainbow patterns were manufactured. Manufactured embossed holograms also contained such optical security features as microtext and laser readable hidden image.

Comparison of diffraction patterns exposed by pulsed and CW lasers on positive-tone photoresist

Two different grating formation geometries for recording onto the positive-tone photoresist with pulsed laser and continuous-wave sources are analyzed and compared. Diffraction efficiency measurements and atomic force microscopy (AFM) examination have been performed in order to investigate the optical and topographical properties of the recorded structures. Gratings patterned by a continuous-wave laser and by a pulsed laser working in the single pulse and multipulse regimes showed different surface roughness and optical properties. The possible reasons for surface roughness and effective exposure differences between gratings created with pulsed and continuous-wave laser radiations are discussed. The processing schemes for diffractive structures patterned by pulsed laser onto positive-tone photoresist for commercial hologram production are analyzed and presented in this work.

Master-holograms recorded with pulsed laser on photoresist

Direct write digital holography technique (DWDH) using single pulsed exposures of 440nm pulsed laser has been applied to record master holograms on commercially available photoresists (ma-P1200 and Shipley 1800 series) of different thickness. Method for numerical evaluation of hologram quality, based on diffraction intensity measurement (reflected beam), was proposed and verified. It was found that all investigated photoresists: ma-P1205, ma-P1225 and S1805, were sensitive enough to record holographic structures at low single pulse laser exposures from the range 3.3 ÷ 19.5 mJ/cm2 . Best quality holograms with well – structured holopixels (hogels) were observed on 0.67 μm thick ma- P1205 photoresist exposed to 11.4 mJ/cm2 and on 0.65 μm thick S1805 photoresits exposed to 13 mJ/cm2, where corresponding measured diffraction intensity had its maximum value. In the case of thicker photoresists (ma-P1225, 3.33 μm), comparable quality of the hogel structure was found in the interval 9.8 – 13 mJ/cm2. Investigation has shown a potential of single pulsed laser exposures to record good quality master holograms on commercially available photoresists applying at least 5 times lower exposures values as compared to CW laser exposures usually used to expose photoresist materials in holographic applications. That opens a possibility to use pulsed lasers for quick origination of master-originals for embossed holograms applying DWDH technique or analogue methods.

Autostereoscopic projector and display screens

Investigated H1-H2 transfer analogue and digitally printed reflection holograms suitability for autostereoscopic projection displays. Proved that reflection hologram, having part of replayed image in front of its surface may be used as autostereoscopic display. Assembled 3D streaming images projection device, incorporating digitally printed reflection hologram. Given recommendation for digitally printed holograms use as 3D projection screens.