Microscope lens system

A beam of a TEMqo laser (Sect. 5.3) with a Gaussian intensity profile is focused to a diffraction-limited spot with the diameter d — 2kf/D by an adapted lens system with the focal length / and the limiting aperture D. For example, with flD= I at = 500 nm, a focal diameter of J 1.0 xm can be achieved with a corrected microscope lens system. This allows the spatial resolution of single cells and their selective excitation by the laser. 

Fig. 2. Lens system used in transmission-type electron microscope. (left I optical convex lens t, Right) electromagnetic lens...

The simplest microscope is the light microscope it consists of an objective lens and an eyepiece. Microscope objectives and eyepieces usually consist of complex lens systems of two or more lenses to correct for lens aberrations (Figure 4.6). The objective lens forms a real intermediate image, which is then magnified by the eyepiece. The objective lens and eyepiece are maintained at a fixed... 

The laser ablation system consists of a high-power pulsed laser, optics to focus the laser at or near the surface of the sample, and an ablation cell. Small ablated particles are swept out of the ablation cell and carried into the ICP in a flowing gas. Often a microscope lens and video camera are positioned to allow the operator to view the sample surface before and after ablation. A high-quality microscope and precise positioning of the sample relative to the laser beam are essential for good spatially resolved sampling. 

Figure 1. UV field illumination of a Plan Apo 100x lens (1.4 NA) derived with a fluorescent plastic slide and the intensity measurement of 10-micron Spherotech beads (obtained from Spherotech, Libertyville, IL, USA). This illustrates the problem of using a lens with improper field illumination to make comparative measurements on a sample. The field illumination pattern shows a bull s eye intensity pattern slightly off-center and the five beads located in different parts of the field to illustrate the variation in intensity occurring by using a lens that has improper field illumination. The intensity of beads was derived by a small Region of Interest (ROI) inside the bead. The five beads show a decrease in intensity relative to the bead in the center of the illumination. Although this figure was obtained with UV optics, it represents the type of field illumination that can also occur with visible light excitation. This pattern is also unacceptable, if a confocal laser scanning microscope optical system is used for a FISH study, as the maximum intensity should be in the center of the objective and not in the corner.

In an ordinary optical or electron microscope, radiation is scattered by the object that one wishes to see at higher magnification. This radiation is recombined by the lens system, resulting in an image of the scattering matter, appropriately magnified. In such a microscope the... 

The collection efficiency of the optical system increases with the square of the effective numerical aperture of the microscope objective lens. A good lens is therefore essential in order to obtain a high coincidence rate. If the sample is transparent the light can be collected from both sides, either by the condenser lens of the microscope or by a second microscope lens. Theoretically, the collection efficiency can be doubled and the coincidence rate increased by a factor of four. Moreover, in a microscope with two aligned microscope lenses exciting and detecting from both sides of the sample, the focal volume can be considerably decreased [64, 448]... 

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