Suppression of forward-scattered light using high-frequency intensity modulation

Laser imaging through a turbid medium is complicated by scattering. Backscattered photons reduce image contrast as weak target returns compete against a large background of backscattered light. Forward scattering broadens the interrogating laser beam, thereby reducing the spatial resolution of the target. Prior research has shown that intensity modulation (<100 MHz ) can be used to “wash-out” the backscatter, resulting in better discrimination of the target and higher contrast. We show that the higher modulation frequencies (>100 MHz ) can be also used to suppress forward scattered light, thereby increasing spatial resolution.