Collinear, two-color optical Kerr effect shutter for ultrafast time-resolved imaging

Abstract

Imaging with ultrashort exposure times is generally achieved with a crossed-beam geometry. In the usual arrangement, an off-axis gating pulse induces birefringence in a medium exhibiting a strong Kerr response (commonly carbon disulfide) which is followed by a polarizer aligned to fully attenuate the on-axis imaging beam. By properly timing the gate pulse, imaging light experiences a polarization change allowing time-dependent transmission through the polarizer to form an ultrashort image. The crossed-beam system is effective in generating short gate times, however, signal transmission through the system is complicated by the crossing angle of the gate and imaging beams. This work presents a robust ultrafast time-gated imaging scheme based on a combination of type-I frequency doubling and a collinear optical arrangement in carbon disulfide. We discuss spatial effects arising from crossed-beam Kerr gating, and examine the imaging spatial resolution and transmission timing affected by collinear activation of the Kerr medium, which eliminates crossing angle spatial effects and produces gate times on the order of 1 ps. In addition, the collinear, two-color system is applied to image structure in an optical fiber and a gasoline fuel spray, in order to demonstrate image formation utilizing ballistic or refracted light, selected on the basis of its transmission time. 16, 1868-1870 (1991). 9. K. M. Yoo, Q. Xing, and R. R. Alfano, "Imaging objects hidden in highly scattering media using femtosecond second-harmonic-generation cross-correlation time gating," Opt. Lett. 16, 1019Lett. 16, -1021Lett. 16, (1991. 10. S. Idlahcen, C. Rozé, L. Méès, T. Girasole, and J.-B. Blaisot, "Sub-picosecond ballistic imaging of a liquid jet,"Exp. Fluids 52, 289-298 (2011). 11. L. Wang, P. Ho, C. Liu, G. Zhang, and R. Alfano, "Ballistic 2-d imaging through scattering walls using an ultrafast optical Kerr gate," Science 253, 769-771 (1991). 12. R. Alfano, ed., Semiconductors probed by ultrafast laser spectroscopy (Academic, 1984, vol. II

Quantitative measurement of binary liquid distributions using multiple-tracer x-ray fluorescence and radiography

“…While a number of techniques have been developed to investigate important phenomena such as liquid breakup processes in the optically dense near-field of sprays [5][6][7][8], relatively few of these techniques have focused on binary liquid mixing prior to the onset of significant breakup and atomization. Conventional methods such as mechanical patternators [9,10] are ineffective in regions where the jets have not fully broken up into droplets, and laser-induced fluorescence [11][12][13] and attenuation techniques [2] suffer from complex refraction patterns at the highly deformed phase interfaces that develop near the impingement point.…”

Sharpness-enhanced ultrafast imaging by using a biased optical Kerr gate

“…The experimental results agree well with the biased OKG theory as described in Eqs. (3) and (5). In addition, it should be noted that the BOKGI signal might be negative at the positive biased angle.…”

“…The temporal resolution of the ultrafast imaging system is determined by the exposure time of the camera, which can be electronically gated on the timescale of picoseconds [1] and even faster by driving the time gate optically. Until now holography and various nonlinear optics effects, such as second harmonic generation [2,3], stimulated Raman amplification [4] and the optical Kerr gate (OKG) [5], have been investigated for ultrafast time gating.…”

Evaluation of optical arrangements for ballistic imaging in sprays

“…These effects, however, typically only become significant at sub-picosecond OKE-gates. For further discussion on this issue see for example work published by the group at CORIA [27,28].…”