Photopatterning of graphene oxide films can be achieved by exposing a thin film of graphene oxide to a photographic flash. Absorption of light causes rapid heating of the graphene oxide resulting in deoxygenation to graphitic carbon. Using a transmission electron microscope grid as a mask, the grid pattern can be transferred to a graphene oxide film.

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A mid-infrared laser absorption sensing method has been developed to quantify gas properties (temperature, pressure, and species density) at MHz measurement rates, with application to annular rotating detonation rocket flows. Bias-tee circuitry is integrated with distributed feedback quantum cascade and interband cascade lasers in the 4−5 m range enabling diplexed radio frequency (RF) wavelength modulation on the order of several MHz while yielding sufficient scan depth to capture multiple rovibrational transitions in the fundamental vibrational bands of CO and CO 2. Sub-microsecond spectrally-resolved CO absorption lineshapes provide for inference of temperature and species from a two-line area ratio and pressure from collision line-width. CO 2 column density is inferred from peak-to-valley differential absorption at the bandhead near 4.19 m. A field demonstration on a methane-oxygen rotating detonation rocket engine was performed utilizing an in situ single-ended retro-reflection optical configuration aligned at the exhaust plane. The target gas properties are temporally-resolved at up to 3 MHz across rotating detonations with up to 20 kHz cycle frequency.