Spatial frequency domain imaging system using a scanning micro-mirror

Spatial frequency domain imaging (SFDI) is a wide-field, noncontact, and quantitative imaging method used to obtain tissue parameters. An SFDI system with a microelectromechanical system (MEMS) scanner in the projector and multitap camera is proposed here. The spatial phase of the structured illumination generated through the grayscale masks is shifted using a MEMS scanner driven at the resonant frequency. The reflected image is captured using a multitap camera with a short exposure time. Structured illuminations with spatial frequencies of 0.1 mm-1, 0.07 mm-1, and 0.05 mm-1 were projected on the two-tone sample. The accuracy of the spatial phase shifting of the structured illumination was analyzed using phase unwrapping. The absorption coefficient and reduced scattering coefficient of the two-tone sample were obtained with a unit exposure time of 5 mu s and total exposure time of 5 ms. The absorption coefficient and reduced scattering coefficient of the sample were measured qualitatively correctly. The deviation between the measured and reference values was less than 8 % for the absorption coefficient and 18 % for the reduced scattering coefficient.