Immersion lens

The direct microscopic count determines the number of viable and dead microorganisms ia a milk sample. A small amount (0.01 mL) of milk is spread over a 1.0 cm area on a microscope sHde and allowed to dry. After staining with an appropriate dye, usually methylene blue, the sHde is examined with the aid of a microscope (oil immersion lens). The number of bacterial cells and clumps of cells per microscopic field is determined and, by appropriate calculations, is expressed as the number of organisms per milliliter of sample. 

With the microfocus instrument it is possible to combine the weak Raman scattering of liquid water with a water-immersion lens on the microscope and to determine spectra on precipitates in equilibrium with the mother liquor. Unique among characterization tools, Raman spectroscopy will give structural information on solids that are otherwise unstable when removed from their solutions. 

Spot size reduction of an optical beam is generally limited if focussing in air is considered due to the NA limit of unity. If the angular spectrum of the waveguide mode field comes close to or exceeds this limit, two ways can be eonsidered. The first one is to widen the mode field by a 2D-taper in such a way that it comes close to a diameter which is available with focus formation in air. The second one is to focus in a high index lens material, and to attach the lens to the lO-chip, finally, just similar to what is achieved with a solid immersion lens. The principal geometry is shown in figure 15. 

I. Ichimura, S. Hayashi, and G. S. Kino, High-density optical recording using a solid immersion lens, Applied Optics 36, 4339-4348 (1997). 

FIGURE 9.1 Amplitude and phase profiles of focal fields. Amplitude (a) and (b) phase in the focal xy-plane. Amplitude (c) and phase (d) in the yz-plane. The phase difference below and above the focal plane is a signature of the Gouy phase shift. The propagation phase was subtracted for clarity. Calculations are for a 1.1 NA water immersion lens and the wavelength is 800 nm. In the panels the lateral axis runs from -1.0 xm to 1.0 xm and the axial axis from -3 4m to 3 xm. 

FIGURE 9.5 (a) Field amplification with a local oscillator field. A linear dependence of the CARS interferometric mixing contrihution is fonnd with increasing field strength of the local oscillator. CARS signals were measured from a dodecane solution at 2845 cm" using a 1.15 NA water immersion lens, (h) Concentration dependence of interferometric CARS contribution in a dodecaneideuterated-dodecane solution, measured at 2845 cm". A linear concentration dependence is found. 

Microscope capable of 1 Ox magnification with a water immersion lens (e.g., Leica DM-LFSA Leica Microsystems). 

Fig. 10.2 Schematic diagram of a reflected interference microscope 1 - tight source, 2 - heat reflecting filter, 3 - coUimator, 4 - diaphragm, 5 - light filter, 6 - photo film, 7 - projection ocular, 8 - semi-transparent silvered mirror, 9 - aperture diaphragm, 10- auxiliary lens, 11 - immersion lens, 12 - sample under investigation, 13 - substrate...

Near-field Raman imaging with a scanned probe has been reported [18, 19]. However, the technique is painfully slow (5-10 h, even for strong scatterers) and it has found very little use. Acquisition time can be decreased by using a polystyrene bead as a very high numerical aperture immersion lens. Working at 532 nm, Kasim et al. used a 60x/1.2 immersion aperture as an optical tweezer to simultaneously position the bead and operate it as a high NA lens [20]. They obtained a spatial resolution of about 80 nm on doped silicon with a few minutes scan time (Fig. 5.1). However, because of the need for a relatively smooth surface and a very intense scatterer, this technique is not likely to find much application in biomedical or pharmaceutical applications [21, 22],... 

The secondary Ion extraction optics should Include an Immersion lens above the sample surface to maximize secondary Ion transmission from the sample surface to the mass spectrometer. An electrostatic analyzer should again be used to filter out high-energy neutral particles and photons from the secondary Ion beam. Energy analysis of the secondary Ions Is generally not necessary, but can be used to vary the amount of fragmentation observed In the mass spectrum (9). 

The second example employs the near grazing primary ion incident on the target which faces the analyzer entrance aperture of a magnetic sector. The scattered ions leave nearly parallel to the surface and the slow molecular ions are drawn out using an immersion lens (37). 

If this equation is compared with the result from light optics where glass bodies are used, one notices that the square-root of the potentials r takes over the role of the refraction indices ne and nr. The relation states that there are different focal lengths in an immersion lens in which the asymptotic potentials >, and 5>r or, correspondingly, the kinetic energies of the electrons... 

Figure 2 Ion source of Herzog and Viehbock A, ion source (canal ray tube) at independent potential B, primary beam C, sample D and E, immersion lens, independent potentials. (From Ref. 9.)...

This is the least expensive optical component, but very important and the most likely to be carelessly chosen. Many objectives are designed and marked to be used with coverslips of a certain thickness, usually 0.17 mm (or 170 5 pm), which corresponds to a thickness grade of 1.5. Ideally, for obtaining the best FISH images, it is recommended that an oil immersion lens is used and these lenses almost always require a 1.5 coverslip for optimal resolution. Any deviation from this thickness leads to spherical aberration, loss in resolution and results in larger and dimmer FISH spots. 

Preliminary examination of the latex involved centrifugation and optical microscopy. Only a marginal tendency to fractionate was noticed after 2 hr of centrifuging several 10-ml samples. The approximate diameter of particles separable by normal centrifuging was near 0.5 fi. An optical microscope was equipped with an oil immersion lens (1000 X) and a phase contrast stage. The polymer particles were noticeable but only marginally visible. Their diameters were near the threshold of reso-... 

Objectives are either dry lenses or immersion lenses. If an air space be present between the o]t)jective and the object, the lens is called a dry one if a liquid is present between the objective and the object, the lens is called an immersion lens. If this liquid be oil, Digitized by Microsoft ... 

The second type of SIMS Instrument the direct Imaging type Is based on the design of Castaing and Slodzlan (IQ). In the direct Imaging Instrument an area 1 to 300 pm In diameter Is bombarded by the primary Ions. The secondary Ions are extracted by an electrostatic Immersion lens which maintains a point to... 

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