Annular illumination

It is clear that rays at the outer rim of the lens contribute most to the depolarization effects. To exploit the depolarization effects for the same type of orientational imaging observed for the SNOM, it has been proposed to use ring-like (annular) illumination [43]. An annular beam can be easily created by removing the central part of the excitation beam using a simple beam stop as symbolized by the black disk in Fig. 7(a). The resulting confocal scan images show very nicely the different effective patterns that can be attributed to different absorption dipole orientations. Some of the patterns are labeled by the respective orientation (see Fig. 7(b)). For details see [42,43],... 

Fig. 11. Environment-dependent single-emitter excited-state lifetimes, (a) Calculation of the decay rates of a single emitter at variable distance to the interface for parallel and perpendicular orientation of its dipole moment, (b) Annular illumination SCOM images for two orthogonal polarizations revealing the orientation of single emitter dipoles embedded in thin film of PMMA. (c) Examples of two fluorescence decays for circled spots A and B in (b). For more details see [50].

B. Sick, B. Hecht and L. Novotny, Orientational imaging of single molecules by annular illumination, Phys. Rev. Lett. 85, 4482 (2000). 

Figure 13.36 Resolution capability of AZ HiR 1075 i-line photoresist used in printing line/space features with 1 1.5 pitch. Processing conditions Film thickness 0.66 iJim on 1300A AZ BARLi II BARC, soft bake (proximity) 90°C/60 seconds (proximity). Exposure tool ASML/400 Scanner. Exposure conditions Dose 170 mJ/cm, annular illumination, NA 0.65, partial coherence a (outer/inner) 0.85/0.55. Postexposure bake (proximity) 110°C/90 seconds. Development 2.38% tetramethyl ammonium hydroxide developer/single puddle for 60 seconds at 21.0°C. (Courtesy of R. Dammel. °)...

Transcutaneous fiber optic Raman spectroscopy of bone using annular illumination and a circular array of collection fibers. J. Biomed. Opt, 11 (6), 060502. 

Hie frill 3D orientation of single molecules can be obtained by other techniques that can determine the absorption or emission transition dipole moment. Annular illumination is a technique that can determine the orientation of the absorption dipole moment, while the 3D orientation of the emission dipole moment can be revealed using defocused wide-field imaging, ° introducing aberrations or by direcdy recording the emission pattern in the objective s back focal plane. In... 

Figure Bl.18.5. Dark-field illumination the aperture of the objeetive is smaller than the aperture of the beams allowed by the annular diaphragm.

Besides improvements in catalyst characteristics [28], the low productivity of a photocatalytic process can also be improved by reactor design. In photocatalytic research on a laboratory scale, the most widely applied reactors are the top illumination or annular reactors containing a suspended catalyst [29]. This type of... 

A number of optical techniques to enhance resolution have been proposed and have played an important role in extending the resolution and life of optical lithography, although they cannot be applied to any pattern sizes or shapes but are pattern-dependent. These techniques include annular and off-axis illumination, phase shift masks, multiple exposures, etc. [505]. 

Inevitably, its determination is somewhat subjective depending on the accuracy of the measuring technique, and the definition of the condition. In the laboratory. a well-illuminated transparent tank and careful observation of the base is all that is required. Observation is made easier, especially in flat-bottomed vessels with four strip baffles, since the last particles to be suspended come consistently either from directly beneath the impeller or the base of the baflSes. In dished bottoms, the centre or an annular ring are the usual final suspension points. Zweitering defined a condition that no particle should remain stationary iqx>n the base for more than 1 to 2s and this condition has been used by many workers. Obviously, there is subjectivity here but a single worker can get about 5% reproducibility. 

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