Thin lasers

The development of models for HCSI combustion has been governed by the similarity of flame growth in HCSI engines and premixed turbulent flames. Thin laser-sheets of only 300 pm thickness were used to measure high-resolution cross sections of the temperature and OH radical distribution in flames of a propane-fueled engine. Figure 8.2.3 illustrates the structure where temperature and OH concentration are closely coupled with super equilibrium values for the OH radical close to the flame front [11]. 

Snetkov IL, Soloviev AA, Khazanov EA (2009) Study of a thermal lens in thin laser-ceramics discs. Quantum Electron 39 302-308... 

Liquid lens showing electrode embedded at each contact circle. Photo on right was taken with thin laser light sheet illuminating liquid lens from above. For visualization, fluorescein dye at 4 ppm concentration was dissolved in double-distilled water. Illumination was from a 488 nm line of an argon ion laser. Yellow fQter was used on the camera lens. (Source Lopez, C.A., C.C. Lee, and A.H. Hirsa. 2005. Applied Physics Letters, 87(13), 134102. With permission.)... 

Compared to the laser triangulometry technique, the originality of this technique lies in the use of a thin laser sheet instead of a crude laser spot. Consequently, measurements of deposit thickness profiles in the direction transverse to the channel can be obtained, by dividing the channel in several ROIs as explained above. The lateral resolution of this technique is defined by the minimum lateral size of the ROIs that can be used, which is 10 pixels (30 pm with the magnification used in our application). However, it must be noted that it is not possible to obtain an accurate thickness value near the channel wall because of the signal being too noisy, probably due to light diffusion from the wall. 

Imaging plates are exposed similar to radiographic films. They are read out by a LASER-scanner to a digital image without any developing process. After optical erasing of the virtual picture the same IP can be used cyclic up to more than 1000 times. The life time is limited by the mechanical stability of the IP s. An IP consists of a flexible polymer carrier which is coated with the sensitive layer. This layer is covered with a thin transparent protective foil. 

Figure C 1.5.13. Schematic diagram of an experimental set-up for imaging 3D single-molecule orientations. The excitation laser with either s- or p-polarization is reflected from the polymer/water boundary. Molecular fluorescence is imaged through an aberrating thin water layer, collected with an inverted microscope and imaged onto a CCD array. Aberrated and unaberrated emission patterns are observed for z- and xr-orientated molecules, respectively. Reprinted with pennission from Bartko and Dickson [148]. Copyright 1999 American Chemical Society.

In a heterostRieture laser, the aetive region ean be defined by epitaxial layers and made eonsiderably thinner. In GaAs/Al Ga. As heterostRietures, the aetive region ean be made as thin as 100 nm, and the threshold euRent... 

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

Nonmilitary infrared apphcations for germanium include CO2 lasers (qv), intmsion alarms, and pohce and border patrol surveillance devices. Germanium is used as a thin-film coating for infrared materials to decrease reflection losses or to provide heavy filtering action below 2 p.m. 

Writing by Bubble Forming. Bubble formation occurs under thin metal layers on polymeric substrate films, caused by local evaporation when hit by a focused laser beam (see Fig. 3c). Bubble formation occurs as in the DIP concept in dye-in-polymer films which are covered by a thin metal (mostiy gold) or ceramic layer (6) (see Fig. 3d). 

Deposition of Thin Films. Laser photochemical deposition has been extensively studied, especially with respect to fabrication of microelectronic stmctures (see Integrated circuits). This procedure could be used in integrated circuit fabrication for the direct generation of patterns. Laser-aided chemical vapor deposition, which can be used to deposit layers of semiconductors, metals, and insulators, could define the circuit features. The deposits can have dimensions in the micrometer regime and they can be produced in specific patterns. Laser chemical vapor deposition can use either of two approaches. 

I. W. Boyd, Laser Processing of Thin Films and Microstructures, Springer-Vedag, Berlin 1987. 

Epitaxial crystal growth methods such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have advanced to the point that active regions of essentially arbitrary thicknesses can be prepared (see Thin films, film deposition techniques). Most semiconductors used for lasers are cubic crystals where the lattice constant, the dimension of the cube, is equal to two atomic plane distances. When the thickness of this layer is reduced to dimensions on the order of 0.01 )J.m, between 20 and 30 atomic plane distances, quantum mechanics is needed for an accurate description of the confined carrier energies (11). Such layers are called quantum wells and the lasers containing such layers in their active regions are known as quantum well lasers (12). 

Pulsed Laser Evaporation. Laser evaporation or ablation consists of using a laser emitting at an appropriate wavelength, generally a KrF excimer laser, in a pulsed mode in a controlled atmosphere to deposit a thin film of a material the composition of which is that of the target (16—18) (see... 

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