The laboratory is equipped with three custom built Balzer BA510 bell jar vacuum deposition plants. Unique within the thin-film industry, the deposition plants have been custom designed so the substrates remain stationary during the deposition and thermal evaporation sources rotate at a fixed geometry below them. By this method the deposition can ensure a stable temperature platform for optical reflection monitoring is obtained, together with the necessary thermal control of the filters being deposited, and good layer thickness uniformity is achieved. The temperature control of the filter substrates is further improved by thermally clamping the substrates to the coating jig by the use of lead washers, backing pieces and disc springs. The filters are deposited at an elevated temperature resulting in hard adherent coatings that are capable of meeting the rigorous demands imposed in space-flight atmospheric sensing instrumentation.
Spectral properties of the filters and coatings are measured using our PerkinElmer Spectrum 2000 Optica FTIR (1.5-40µm) and a Hitachi U3400 UV-VIS-NIR grating spectrometer (187nm - 2.6µm). The PerkinElmer Spectrum 2000 Optica FTIR instrument differs from normal FTIR instruments in that it has been specially designed with a series of half apertures and baffles to minimize spectral artifacts due to double modulation. Both instruments are capable of measuring in both transmission and reflection to high accuracies. Cryogenic spectral transmission measurements are performed using an Oxford Instruments total immersion Helium Optibath cryostat (450 - 4K) or an Air Products Displex cooler (300 - 15K).
Environmental testing can be performed according to the general provisions of MIL-F-48616 military specification or agreed testing requirements. To this end the laboratory is equipped with humidity and temperature cycling chambers for the environmental testing of filters together with facilities for adhesion and abrasion testing along with microscopic and image processing examination.