Rayleigh range

Figure 3. The phase lag produced by the Gouy phase, calculated using the analytic model described in the text for 0)3 + 3t0i excitation, with two additional coi photons in one of the channels. The calculations are performed for various ratios of the molecular beam radius d to the Rayleigh range zr.

Fig. 13.5. Femtosecond pulse loosely focused into water creates a long filament with a nearly constant diameter that extends over many Rayleigh ranges (left), and generates a broad supercontinuum spectrum (right). This seemingly stationary filament is created by a series of very dynamic multiple pulse splittings illustrated in the following...

For self-similar particle size distributions, the average particle size can be determined directly by measuring the extinction. Total scattering in the Rayleigh range is... 

For particles smaller than the wavelength of light used, that is, for the Rayleigh range, the scattering intensity is a strong function of the diameter (sixth power), the wavelength (fourth power) and the complex refractive index ratio as described by the equation ... 

Figure 11.10 A plot of w(z) and the corresponding spatial dependence of the two-photon transition probability for an excitation wavelength of 800 nm and a minimum spot size of 1 pm. Approximately 82% of the two-photon absorption takes place within the Rayleigh range Zr about the focal point at Z = 0, leading to an effective focal volume of ca. 32 x 10 litres (32 fl)...

Figure 11.11 A direct comparison between the spatial dependence of two- and single-photon absorption from a fluorescent probe in an isotropic solution contained in a cuvette and viewed at 90° to the excitation direction. Single-photon excitation at 488 nm produces fluorescence throughout the sample, whereas the restriction of two-photon fluorescence (excited at 800 nm) to the Rayleigh range around the laser focus is evident. The photographs were provided courtesy of Dr Mireille Blanchard-Desce (CNRS UMR 6510 Rennes)...

---