Investigation of separating the transmitted and scattered light beams in free space by ultrafast optical switches

In this paper, the separation of transmitted and diffused light beams in a scattering medium by a magneto-optical ultrafast switch is investigated. The magneto-optical switch previously developed by the authors is capable of 1 ns switching speed and has a 1 mm clear aperture. The diffused light beams and ballistic beams in a scattering medium are simulated in the lab by two beam paths. One beam is delayed from the other to simulate the diffused light beam and the ballistic beam, respectively. The magneto-optical switch is synchronized with the required delay to the laser pulse to keep only the ballistic beam, acting as an ultrafast light gate. The concept is demonstrated with a 532nm Q-switched pulsed laser.