Mid infrared optical coatings are commonly designed & manufactured using typically electron beam evaporated films of Silicon and Silicon oxide. However the transparency of these coatings is limited by optical absorption in the films when producing coatings for wavelengths beyond 4um approximately. This work reports improvements in mid infrared (3 to 6um) filter transparency achieved by exploiting recent advances in microwave plasma assisted pulsed DC magnetron sputtering technology. Sputtered silicon compound films have been used to demonstrate efficient room temperature deposited optical coatings for gas sensing applications at wavelengths between 3 to 6um. This process technology allows a new selection of film materials to be used in design of mid infrared filters, with transmission and thermal drift characteristics enhanced compared with conventional electron beam evaporated coatings. The spectral location of the optical coatings is controlled by a non-optical method, which avoids the complex optical monitoring configurations normally required. Durable filters are obtained at room temperature, which would otherwise be required in conventional evaporation processes. Importance of water partial pressure control during deposition for mid infrared is emphasised.
Raman spectroscopy is an important technique that has evolved into many advanced methods, used in a wide range of fields, ranging from artwork analysis to security. In this study, we have found through template-assisted glancing angle deposition, highly ordered silver nanostructures could be fabricated across a nano-imprinted polymer to produce surface enhanced Raman scattering substrates. Various nominal film thicknesses at 85° incident angle and then deposition angles were used to fabricate the substrates, which were then characterised by scanning electron microscopy and their Raman performance was assessed using trans-1, 2-bis (4-pyridyl) ethylene as the Raman probe. Observations show that the best thickness for glancing angle deposition at 85° to be 400 nm (relative to the quartz crystal microbalance) produced the best Raman signal enhancement. The nanostructures consisted of nanorods with 851 – 1360 nm average length. Scanning electron microscopy images reveal samples had good uniformity and consistency in all films grown by this method, as the surface features provide regularly spaced nucleation sties. These findings lead show that highly sensitive surface enhanced Raman scattering substrates can be reproduced consistently cheaply.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.