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Stochastic subwavelength structures on polymethylmetacrylate (PMMA) surfaces were produced by low-pressure argon/oxygen plasma treatment. The modified surfaces show antireflective properties exhibiting low scattering losses depending on the size and the density of the structure. It is demonstrated that the antireflection performance is a function of the mean ion energy and working pressure that are controllable by process parameters, namely plasma power and gas flow. A model is suggested that assumes a self-assembling etch mask as reason for the growth of the pins with about 70–90 nm in lateral dimension and up to 600 nm in height.

The application of plasma treatment on transparent PMMA substrates has shown an effect of reducing surface reflection. This effect is based on a refractive index gradient created by a combination of chemical decomposition and physical etching on the polymer surface. A stochastic nanostructure was found by means of AFM and SEM. Conditions for the plasma treatment process and properties of the modified PMMA surfaces have been discussed.

High transparent thermoplastics have the capability to put glass out of business, especially in everyday life's optics. Their diverse nature gives rise to different antireflection principles. The reduction of surface reflection losses in polymethylmethacrylate (PMMA) is demonstrated by means of argon/oxygen plasma treatment. Since the presented reduction of reflection occurs in a wide spectral range, the technique may be applied for omnidirectional devices or curved substrates. The etching process creates a self-organized stochastic subwavelength structure at the substrate itself. The decrease in reflection is described by effective medium theory (EMT), converting the surface topology into a depth-dependent filling factor profile. In a second step this nano-scaled structure is used as the initial point for a broadband absorber by coating it with a nontransparent metal layer. A high-efficient absorber can be obtained, if the metal acts as backside coating of the double-sided plasma-treated substrate and steady-going transitions between the materials eliminating the Fresnel reflections. In practice, the magnitude of absorption depends on depth of structure as well as on the complex refractive index of the metal.

Antireflection (AR) properties are required for optical surfaces to avoid disturbing reflections as well as to improve the transmission of optical systems. The common method to reduce the reflection on optics is vacuum deposition of interference coatings. However, special efforts are required for each type of plastic to develop polymer-capable vacuum coating processes due to the manifold chemical and physical properties of optical polymers. An alternative procedure for the antireflection of polymers is the generation of surface structures that decrease the index of refraction in a surface region. In this paper, the suitability of the miscellaneous thermoplastic polymers for plasma-ion assisted deposition processes is evaluated. This comprises the study of damage effects caused by the contact with plasma and high-energy radiation as well as the development of special coating designs and of suitable process conditions. Coating properties achieved are discussed for PMMA and poly-cycloolefines. The same ion source arrangement as used for coating has been applied for etching an antireflective sub-wavelength surface structure into PMMA. In summary, the paper shows the practical application fields for both technologies.