Holographic patterning of acrylamide-based photopolymer surface

Abstract

Abstract:The patterning of an acrylamide-based photopolymer surface by holographic recording is studied. The patterns are induced by light alone and no post-processing is required. Periodic surface modulation is observed in addition to a volume phase grating. An investigation has been carried out using white light interferometry into the dependence of the amplitude of the photoinduced surface relief modulation on the spatial frequency, intensity of recording and sample thickness. The observed dependencies indicate that the diffusion of material during the holographic recording plays a major role in surface relief formation. The possibility for inscription of surface relief patterns opens the door to at least two new applications for this photopolymer: fabrication of diffractive optical elements and biosensors.

Photoinduced surface relief studies in an acrylamide-based photopolymer

“…This model is applicable to systems where the peaks of the surface relief appear in the non-illuminated areas [24]. The second model is based on the assumption that redistribution of system components by diffusion is responsible for the relief formation, and suits systems such as ours where experimental observation shows the surface relief peaks appearing in the illuminated areas [1,2,15,16].…”

“…The most probable reason for the strong dependence of the surface relief modulation on the TEA concentration is TEA's plasticizing role. With the increase of the number of TEA molecules the layers become less viscous and there could be a possibility of diffusion of short polymer chains into dark regions [16] which in turn decreases the amplitude modulation. Experiments were carried out to study the influence of temperature on the surface relief amplitude modulation.…”

“…It has significant advantages in measuring surface profiles as the measurement is non-contact with very high vertical resolution. An investigation of the photoinduced surface relief modulation in thin and thick layers of an acrylamide-based photopolymer system [15,16], developed at the Centre for Industrial and Engineering Optics, Dublin Institute of Technology, was reported earlier [17,18]. The resolution of the material was improved to enable reflection holograms to be recorded.…”

Fabrication of switchable liquid crystal devices using surface relief gratings in photopolymer

“…The variation of thickness as a result of photopolymerization is referred as a surface relief grating. Previous studies on photoinduced surface relief gratings in this material [11,12] strongly indicate that a concentration gradient created by nonuniform polymerization causes mass transport of monomer from dark to bright regions and this is the main mechanism which governs the formation of surface relief gratings. Extensive investigation of the dependence of the photoinduced surface relief gratings on physical and recording parameters was reported earlier [11,12].…”

“…Previous studies on photoinduced surface relief gratings in this material [11,12] strongly indicate that a concentration gradient created by nonuniform polymerization causes mass transport of monomer from dark to bright regions and this is the main mechanism which governs the formation of surface relief gratings. Extensive investigation of the dependence of the photoinduced surface relief gratings on physical and recording parameters was reported earlier [11,12]. Switchable LC diffraction gratings were successfully fabricated by filling the surface relief gratings of spatial frequency 70 lines/mm with E49 LCs and the switching behaviour was demonstrated [13].…”