Lens illumination

Fig. 20-5 On-axis lens illumination ofa fiber assuming equal beam and lens radii. The focal point of the lens is on the endface.

The expression in Eq. (20-30) for the fundamental-mode efficiency is also the result which we would obtain using the Gaussian approximation of Eq. (20-24) for an arbitrary profile. Thus we have a general expression for lens illumination. For example. Table 15-2, page 340, gives Tq = p/(21n for the step profile, and at K = 2.4 the error between Eq. (20-30) and an exact analysis is less than 1 % [10]. 

Figure 2. Exanple of solid itmnersion lens illuminated beyond its cutoff angle to illustrate the difference between far-field and near-field properties.

Figure Bl.18.11. Confocal scanning microscope in reflection the pinliole in front of the detector is in a conjugate position to the illumination pinliole. This arrangement allows the object to be optically sectioned. The lens is used to focus the light beam onto the sample and onto the pinliole. Thus, the resulting point spread fimctioii is sharpened and the resolution increased.

Fig. 6. Schematic diagram of a Raman microprobe where BS = beam splitter, L = lens, and MI = mirror, (a) The illumination pathway (b) the collection...

There are two types of scanning acoustic microscopes. If the illumination and the reception of the acoustic waves are performed by two identical lenses arranged confocally, the SAM is called a transmission SAM. The lens geometry used for transmission imaging is shown schematically in Fig. 41 [93]. 

Figure 7.3 A schematic of a two-beam photon-force measurement system. Obj objective lens (lOOx oil immersion, N.A. 1.4), PBS polarization beam splitter, FI color filter for eliminating red illumination laser beam, F2 color filter for eliminating green illumination laser...

Figure 5. Schematic arrangement for hologram formation with an electron biprism. A plane wave illuminates the specimen placed off-axis. After the object lens a wire is placed between two earthed plates. The wire is the electron optical analog of a Fresnel biprism and causes the unperturbed and perturbed waves forming the electron hologram to interfere. The object phase-shift causes a displacement in the hologram fringes, and is thus observable.

Figure 5.15 shows a ray diagram for a light-optical projection microscope. The light source is placed behind a condenser system which collects the light which is diverging from the source and illuminates the specimen. The presence of the variable aperture near to the condenser lens permits control of the area of the specimen which is... 

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