Fig. 3.

SFDI instrumentation and processing scheme. (a) A typical SFDI setup where a computer controls the camera, LEDs, and DMD. LED, light-emitting diode; CL, condenser lens; DM, dichroic mirror; DMD, digital micromirror device; P, polarizer; L, lens; and Cam, camera. (b) SFDI processing pipeline from raw data to tissue optical property maps and scatter-corrected chromophore concentrations. Raw intensity images at each wavelength are collected at two or more spatial frequencies, $f_0$ and $f_x$. Images with each $f_x$ are taken at three different phases (0 deg, 120 deg, and 240 deg) of the spatially modulated pattern. Next, the diffuse reflectance is calculated at each spatial frequency and wavelength. Using light-transport models, the optical properties (${\mu }_a$ and ${\mu }_s^{\prime }$) as a function of wavelength $\lambda$ are obtained. The scatter-corrected absorption can then be used to obtain chromophore concentrations (i.e., $C_{\mathrm{HbO}2}$, $C_{\mathrm{HbR}}$, $C_{\mathrm{HbT}}$) and tissue oxygenation (${\mathrm{StO}}_2$).