Fig. 1. Collimating transmission system

Fig. 2. Flow chart of our algorithm

Fig. 3. Structure diagram of SFDI

Fig. 4. Flow chart of system operation

Fig. 5. Flow chart of SFDI technique

Fig. 6. Diffuse reflectance fitting curves of steady state and high frequency at 529 nm and 617 nm

Fig. 7. Experimental results of melanin phantom. (a) Fitting curve of absorption coefficient obtained by SFDI and collimated transmission systems at wavelength of 529 nm; (b) fitting curve of absorption coefficient obtained by SFDI and collimated transmission systems at wavelength of 617 nm ; (c) collected mass concentration of melanin

Fig. 8. Experimental results of blood phantom. (a) Blood oxygen saturation in ground state, deoxygenation process, and oxygen blowing process; (b) change trend of oxygenated, deoxygenated, and total hemoglobin concentrations; (c) change trend of blood oxygen saturation

Fig. 9. Experimental results of arterial occlusion. (a) Deoxygenated hemoglobin concentration; (b) oxygenated hemoglobin concentration, (c) blood oxygen saturation; (d) change trends of oxygenated, deoxygenated, and total hemoglobin concentrations; (e) change process of blood oxygen saturation; (f) absorption coefficient at 529 nm; (g) absorption coefficient at 617 nm