Long-working-distance microscopic imaging through a scattering medium using supercontinuum illumination

Abstract

We demonstrate long-working-distance microscopic imaging through scattering media, in which a homemade long-working-distance microscopic imaging unit is used to increase the spatial frequency and a femtosecond-laser-induced supercontinuum is used to suppress the harmful speckles to improve object visibility. Although the aim of the imaging system is to study the real fuel spray, the presented work is mainly to focus on the performance of this long-working-distance microscopic imaging system. The results shows that the working distance and the maximum spatial resolution of our imaging system could reach up to 20 cm and 3.5 μm, respectively. Even when the optical depth of the scattering media reaches approximately 12, the maximum spatial resolution could be maintained at 3.8 μm. Compared with some previous imaging systems for fuel spray diagnostics, our long-working-distance microscopic imaging system shows the best overall performance and offers a good candidate for imaging the microscopic structures of fuel sprays.