UC Irvine

We are developing a method for simultaneous multi-band spatial frequency domain imaging (SFDI) and blood flow mapping by multi-exposure laser speckle contrast imaging (MELSCI) with a laboratory-designed 2x2-aperture 4-tap CMOS image sensor. Four-tap CMOS image sensor can capture four images synchronized with controlled illuminations and can implement flexible exposure. Although we have demonstrated SFDI with suppressing motion artifact and ambient light bias and efficient video-rate MELSCI based on a four-tap CMOS image sensor separately, simultaneous multi-modal imaging is effective for improving the accuracy of medical diagnosis. The image sensing area is divided into 2×2 regions, and each region is equipped with optical filters and an imaging lens. By using optical bandpass filters, multi-wavelength imaging and wavelength-division multiplexed imaging are realized. Using the fabricated image sensor, we observed a human wrist. 450, 550, 660nm LEDs were used for 3-band SFDI, and a 785nm LD was used for MELSCI. In order to measure a change in the blood flow speed, an examinee was measured before and after an exercise (squatting 30 times). The unit exposure duration for SFDI and MELSCI was 10ms. The pattern was generated by a DMD. The spatial frequency of the projected sinusoidal patterns was 0.1mm-1. MDC and MAC maps for the three wavelengths by SFDI, and K2 value maps by MELSCI were successfully obtained.