UC Irvine

We have developed a motion-resistant three-wavelength spatial frequency domain imaging (SFDI) system using an 8-tap CMOS image sensor. We have successfully measured two wavelengths using the same sensor. However, to remove the effect of melanin, measuring at three wavelengths is needed. In this study, the Hilbert transform is introduced to reduce the number of captured images for each wavelength from three to two. In the experiments, a DMD was illuminated with LEDs with wavelengths of 660nm, 780nm, and 850nm. One plane and one sinusoidal pattern were projected on the specimen for each wavelength. In addition, one ambient light image was captured to extract only the reflection components for the projected patterns. Pattern projection and exposure were repeated multiple times at a faster frame rate than the video rates to suppress the motion artifact while keeping appropriate signal levels. Totally 7 images were captured at once. Using this system, we demonstrated suppression of motion artifacts and ambient light in capturing a moving wrist.