Tight microscopy techniques

Raman microscopy techniques, discussed in Chapter 11, in which the laser is usually tightly focused. 

Scanning transmission electron microscopy (STEM) is a standard microscopy technique that images single atoms with a tightly focused beam [SOUtll]. The same restrictions apply as for STM, with the additional constraint that only fairly heavy atoms (e.g., uranium) can be successfully imaged. 

In terms of beam delivery, the DLW method is based on optical microscopy, confocal microscopy [4,6,13] and laser tweezers [14] (for reviews on laser tweezers see [ 15,16]). These techniques allow for a high spatial 3D resolution of a tightly focused laser beam with optical exposure of micrometric-sized volumes via linear and nonlinear absorption. In addition, mechanical and thermal forces can be exerted upon objects as small as 10 nm molecular dipolar alignment can be controlled by polarization of light in volumes of with submicrometric cross-sections. This circumstance widens the field of applications for laser nano- and microfabrication in liquid and solid materials [17-22]. 

Two-photon molecular excitation was performed by very high local intensity provided by tight focusing in a laser scanning microscopy (LSM) [37]. This technique was combined with the temporal concentration of femtosecond pulsed lasers... 

Because external labels are not required, the signals are not limited by bleaching of the probe as they usually are in fluorescence microscopy, nor perturbed by effects of the probe on the sample. The quadratic dependence of the signal on the intensity of the second beam, combined with the linear dependence on the intensity of the first beam, allows very tight focusing of the image. Finally, the technique can be remarkably sensitive, as shown by studies of single lipid bilayers [84-86]. 

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