Abstract

The picosecond optical Kerr gate^1–3 (OKG) has been used as a simple ultrafast shutter to measure ultrafast events and relaxation processes. This gate can be used for imaging, communication, and digital computation. For a single-stage optical Kerr gate (SOKG), the signal to noise ratio (SNR) of −2×10³ and. the gate opening time of ~10 ps have been commonly achieved using a 10-ps pulse from a mode-locked glass laser. In time-gated optical imaging in biological and medical samples, higher SNR (>10¹⁰) and shorter opening time (−1 ps) are needed to remove the diffusive noise for better spatial resolution. In this paper, the operation of a cascaded double-stage optical Kerr gate (DOKG) system to improve the SNR and the gating time is described. An improvement of −5011 times in SNR was achieved over that of a SOKG system. The transient gating time of a DOKG can be 10 times faster. Images of test bar chart behind modeled systems and tissues are discussed.

© 1992 Optical Society of America