Differential luminescent imaging method

Abstract

Luminescent imaging is an area of active research for obtaining physical and chemical properties of a flow. Oxygen-sensitive luminescent probes are used as pressure-sensitive paints to capture unsteady flow over a fluid dynamic surface. The luminescent output is acquired by a photo-sensitive imaging chip, such as CCD and CMOS. Because these imaging chips acquire a digital signal, luminescent imaging is a poor technique for the measurement of small changes in the signal, which is equivalent to or lower than the noise level. A differential luminescent imaging method is studied to capture small fluctuations in a signal level. A theoretical model to describe the differential method is introduced and validated by experiments. Based on the static characterization, it is shown that the differential method possessed its sensitivity to capture fluctuations as small as 0.002% of the mean signal, which is an improvement in sensitivity by a factor of 81 as compared to the conventional luminescent imaging method.