Projection lens

This is possible because the projection lens system, which for clarity was not shown in Figure 4.7, is normally included behind the objective lens and below the source image plane. This lens system allows the projection of both the diffraction pattern and the specimen image on the observation screen. In Figure 4.8, [50] the electron diffraction pattern of a Fe thin film is shown. In Figure 4.9, the transmission electron micrograph of the mordenite included in the sample CMT-C (see Table 4.1), where fiber-like crystals of mordenite are seen, is shown [51],... 

Wafer cassette Reticle Exposure Projection lens stage... 

In mathematical terms, the low-pass filtering function of the projection lens can he described in the following manner for the special case of a rectangular grating, where p sin 6 mX describes the positions of the discrete coherent diffraction orders. If the lens is described in terms of a two-dimensional pupil function H(u, v). 

Projection optical lithography has been the mainstream technology in the semiconductor industry for the last two decades [2]. Figure 9.2 shows a schematic depiction of an optical projection system consisting of a laser light source, a mask, a projection lens, and a resist-coated wafer. The projection of the pattern of the mask onto the resist layer provides a demagnification ratio of up to 4x. 

The use of a light beam as an indicator avoids the errors caused by friction with a normal pointer, while a hairline incorporated in the projection lens eliminates errors due to parallax, and with the scale at a distance of 1 m from the mirror, a sensitivity of up to 1 S(X)mm//tA can be achieved. 

An 18 mm square area of the LC cell is projected onto a 15-inch square screen. Actually the system is designed to project two LC cells for experimenting with a multi-color display. White light from a xenon arc lamp is separated by a dichroic beam-splitter into two spectral components. Each half of the system is similar to that of Fig. 8 and the two paths are recombined by a second splitter before the final projection lens. With no information on either cell, the screen appears white. 

In principle, the image of the filament precisely fills the aperture of the projection lens. If the image is larger than the aperture of the projection lens, then the lens is said to be overfilled, and light from the extremities of the filament is wasted. Conversely, if the projection lens is underfilled, then its full aperture is not used, and resolution may suffer. The principle of filling the aperture is important in other optical systems as well (see below). 

Unlike most field lenses, the field lens directly before the eyepiece does not project a pupil into the plane of the eye lens because, if it did so, the eye relief would be 0. In almost all other cases, however, the function of a field lens is to project a pupil into the plane of some other lens, and, indeed, the combination of the field lens and the eyepiece projects a pupil into the pupil of the eye. Any system of relay lenses similar to a terrestrial telescope, such as a periscope (which uses mirrors to look along a line of sight displaced from the line of sight of the eye), must necessarily use the principle of projecting a pupil into the apertures of successive lenses. The diameter of any lens is chosen to be equal to the diameter of the appropriate pupil, much as the diameter of a projection lens is matched to the image of the projection lamp. 

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