Dry photopolymer films for computer-generated infrared radiation focusing elements

Abstract

A new technological approach makes fabrication of relief computer-generated focusing elements for IR radiation by use of a dry photopolymer recording material possible. The formation of a relief structure by self-development takes place in the dark, subsequent to the holographic illumination, without wet processing. Consequently these diffractive elements exhibit low surface scattering. The formation of a surface wave of the monomer along the light-darkness boundary is observed for the first time to our knowledge and confirms the previously proposed thermodynamic model of the mechanism of the hologram formation in photopolymerizable layers. Dye-sensitized polymerization of acrylamide is found to produce nonlinearity of the relief recording. At least partial compensation of this nonlinearity is attained by the introduction of appropriate corrections into the computer-generated amplitude function. A diffraction efficiency of ~ 55% is obtained for CO(2) laser radiation (λ = 10.6 µm).

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].…”

“…Photoinduced surface relief gratings in a photopolymer are attractive for their applications in diffractive optical elements [1,2], optical data storage [3], recording computer generated holograms [4] and the alignment of liquid crystals [5][6][7][8]. There has been extensive growth of technological applications of liquid crystals, such as photonic components and liquid crystal displays (LCDs) in the last two decades.…”

Investigation of the sensitivity to humidity of an acrylamide-based photopolymer containing N-phenylglycine as a photoinitiator

“…They contain monomers such as acrylamide (AA) and N, N'-methylene bisacrylamide (BA), electron donor (photoinitiator), a light absorbing dye and a polymer binder such as polyvinyl alcohol (PVA). Triethanolamine (TEA) is usually used as a photoinitiator [20][21][22][23]. Photopolymers have a number of advantages: a wide dynamic range, high sensitivity, low scattering, self-processing nature and relatively low cost.…”

Holographic patterning of acrylamide-based photopolymer surface

“…Photoinduced single step inscription of a surface relief modulation in photopolymer systems opens attractive perspectives for applications such as diffractive optical elements [1,2], recording of computer generated holograms [3], and biosensors. Important characteristics of the material in relation to these applications are its spatial resolution, the amplitude of photoinduced surface relief, the required recording time for achievement of maximum surface modulation and its long-term stability.…”

“…For optimisation of all these characteristics a thorough understanding of the mechanism of surface relief formation under light illumination is necessary. Although photopolymer systems have been a subject of constantly increasing interest, especially after the development of self-processing photopolymer systems, only a few investigations dedicated to the surface relief formation have been reported in the literature [1,2,4,5].…”