The National Research Laboratory of Metrology (Ibaraki, Japan) has demonstrated an ultrafast, time-resolved, two-dimensional (2-D) imaging system that uses a femtosecond-amplifying optical Kerr gate for three-dimensional (3-D) shape measurement of a completely diffusing surface. The device reportedly can measure stepped and spherical surfaces with high spatial resolution and sensitivity because of a short opening time of 459 fs and a maximum transmittance of 185%.
According to researchers Kaoru Minoshima, Hirokazu Matsumoto, and Takeshi Yasui (who is now at Osaka University), the optical Kerr gate (an ultrafast optical switch that uses the optical Kerr effect) has several advantages as a tool for time-resolved imaging of diffusing surfaces. For example, real-time 2-D imaging and a wide spectral bandwidth are possible because of freedom from the phase-matching condition and high sensitivity in the picosecond region. A move into the femtosecond region, however, can necessitate a trade-off between high sensitivity and fast response, limiting gate performance in time-resolved imaging. Minoshima and colleagues resolved the issue using techniques originally developed to amplify optical Kerr gates in the picosecond region.-- Courtesy O plus E magazine, Tokyo