Second harmonic optical coherence tomography

Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular and tissue structures, this technique offers contrast and resolution enhancement to conventional optical coherence tomography.Comment: 3 pages, 5 figures. Submitted on November 8, 2003, this paper has recently been accepted by Optics Letter

ROTATION MOVEMENT ANLYSIS IN TAEKWONDO POWER BREAKING MOVEMENT OF 360° JUMP BACK KICK

The purpose of this study was to investigate reaction force of both legs of 360° jump back kick in Tawkwondo. Eight Taekwondo coaches (Height: 175.7±5.7cm; Weight: 75.0±7.9kg; Age: 28.0±4.2years) performed this kick movement to break one inch board. The equipment included ten Vicon cameras (MX13+, 250Hz) and two Kistler force platforms (1000Hz). Kinematic and kinetic data were collected by Nexus software. All variables were calculated by custom written program of MatLab. The results showed that the swing leg provided the push force allowing the axis leg to rotate in rotation phase. The axis leg not only relied on the vertical GRF and impulse obtaining jumping height and moving distance but its joints angle change also balanced the entire body. In conclusion, the interaction of both legs in start-up phase as well as the posture of axis leg during in rotation phase determined the rotation motion of 360° jump back kick in Taekwondo