Picosecond-pulsed laser

Since then, number of researcher have studied and experimented with TRS including Chance and Oda [61] [63] [76] [80] [81] [73] [82] [113] [114], TRS instruments rely on a picosecond pulsed laser with a detector that is designed to detect the time evolution of the light intensity [44], With the time profile of light intensity through the medium, it is possible to measure both absorption and reduced scattering coefficients [32], A ma-... 

Further improvement is achieved using a picosecond-pulsed laser light source in contrast to a continuous one. Time resolution thus is determined by the lifetime of the probe beam instead of the response time of the detector in analogy to picosecond time resolved experiments in the visible spectral range (for a recent review see Stoutland et al., 1992). 

The influence of laser fluence and pulse duration time on microscale heat tiansfer mechanisms are investigated by using one-dimensional said transient equations of eerier and lattice temperatures. The scale difference between energy relaxation and laser pulse duration times results in file fiiermal non-equilibriimi state fiiat can be controlled by laser fluence as well as pulse dmation time. In the case fiiat a few picosecond pulse laser is irradiated over file semiconductor surface with relatively hi fluence, a two-peak structme in file carrier temperature variation can be observed. As pulse dmation increases, file m imiun eerier temperature and file number density decrease, whereas file lattice temperature is nearly of constant values. Meanwhile, the two-peak structme due to Auger heating disappears and converts into the one-peak stinctme as file laser fluence decreases. 

Agassi, D. (1984) Phenomenological Model for Picosecond Pulse Laser Annealing of Semiconductors, J. Applied Physics, Vol. 55, pp. 4376-4383. 

The photophysical dynamics of o-HBP was investigated by the Temp.G method with a picosecond pulsed laser (pulse width 30ps) [164]... 

The solid angle is defined as the ratio of infinitesimal area normal to Cl, to the square of the distance between two infinitesimal surface elements exchanging radiation (see Fig. 7.2). Note that radiation intensity may vary as a function of location r= r(x, y, z), direction Cl = ft(0, <()), time t, and wavelength X therefore, it is a function of seven independent parameters. For most calculations of interest, the transient nature of radiation intensity is not critical. Recently, however, with the advances in femto- and picosecond pulsed lasers, the transient radiative transfer applications have started becoming important (see, e.g., Ref. 4) nevertheless, we will not cover these advances in this chapter. 

The physics behind laser ablation is much more complicated than as explained above. Three characteristic timescales are involved to define the nature of laser interaction with a metallic material [1], They are the electron cooling time lattice heating time Tj, and laser pulse duration tl. For a nanosecond pulse laser, tL 3> Xi. the process is predominantly laser heating. For a picosecond pulse laser, x femtosecond pulse laser, the process is exclusively a laser ablation process. Laser ablation of semiconductor and dielectric materials involves different mechanisms [2]. 

The high peak powers delivered by sub-picosecond pulsed lasers such as Ti-sapphire enable multiphoton excitation of endogenous and extrinsic fluoro-and luminophores.. The development of robust and easy-to-use laser systems has made multiphoton microscopy a rapidly emerging technique for imaging [75]. 

Tanaka, Y. Hara, T. Kitamura, H. Ishikawa, T. (2000). Timing Control of an Intense Picosecond Pulse Laser to the SPiing-8 Synchrotron Radiation Pulses. Reoiew of Scientific Instruments, Vol.71, No.3, (March 2000), pp. 1268-1274, ISSN 0034-6748 Tanaka, Y. Fukuyama, Y. Yasuda, N. Kim, J. Murayama, H. Kohara, S. Osawa, H. ... 

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