Illumination intermediate image

Fig. 16. Illumination of the optical spectrometer with lenses. (A) Imaging on the entrance collimator, (B) illumination with intermediate image, (C) imaging on the entrance slit.

Illumination with an intermediate image. Here a field lens is used to produce an intermediate image on a diaphragm. To illuminate the collimator mirror fully, the appropriate zone can be selected with the aid of a lens placed immediately in front of the exit slit. A third lens is used to illuminate the entrance slit homogeneously (Fig. 16B). The magnification is then divided over all 3 lenses, thus chromatic aberrations... 

A) Imaging on the entrance collimatm B) Illumination with intermediate image C) Imaging on the entrance slit For explanation of symbols see text... 

Figure 5. Image path of the phase contrast microscope, convening phase shifts into a noticeable contrast a) Illuminating diaphragm ring b) Condenser, c) Specimen generating a phase shift d) Objective plate e) Phase plate 0 Intermediate image...

Figure 6. A) Image path of a Iwo-beam interference microscope B) Nomarski prism with direction of optical axes and position of interference plane indicated a) Polarizer (45°) b) First Wollaston prism c) Condenser d) Specimen e) Objective f) Second Wollaston prism g) Analyzer (135°) h) Intermediate image Contrast is generated by a phase shift of the polarized and prism-split illuminating beam.s, which are combined by the second prism...

Figure 13. The laser light is focused via the scanner (b) through the tube lens (c) and the objective (d). and illuminates a small spot in the specimen (e). Emitted light emanating from the focal plane and the planes above and below (dotted and dashed lines) is directed via the scanner to the dichroic beam splitter (a) where it is decoupled and directed onto a photomultiplier (i). A pinhole (h) in front of the photomultiplier is positioned at the crossover of the light beams emerging from the focal point. This plane corresponds to the intermediate image of the Kohler illumination described in Section 29.1.3. Light emanating from above and below the focal point has its crossover behind and before the pinhole plane so that the pinhole acts as a spatial Filter. Numerous papers elucidate the basic aspects of confocal image formation [59] - [64].

A typical IR microscope is all-reflecting, with visible illumination for visual examination of the sample and with a dedicated on-axis small area mercury-cadmium telluride (MCT) detector. The sampling size can vary from less than 50 x 50 p.m in linear dimensions to the dimensions of the detector element. The sample is placed on a standard microscope X-Y stage and can be visually examined under a variety of magnifications. The sample area of interest is isolated by placing a variable aperture on an intermediate image of the sample within the barrel of the microscope. 

More complex electron microscopes use additional lenses, both above and below the specimen. The condenser lenses above the specimen concentrate the electron beam and increase the illumination. The addition of intermediate lenses below (he specimen make it possible to go to higher magnification in the final image. Various alignment controls, apertures for the lenses, specimen handling devices, and suitable airlocks and anticontamination traps also are provided. 

Rheinberg differential color contrast (22.231. in which the normal and oblique illuminating rays have different colors. Fine detail in the image of the specimen appears with a color different to that of the coarse detail. This technique maximizes illumination, and is useful when attempting to highlight disclinations without loss of intermediate detail. It appears to be a novel technique in the context of liquid crystalline microstructures. 

The objective lens is the most important lens for a transmission electron microscope. The condenser lenses are the next most important, the combination of these condenser lenses forms different electron beam to illuminate TEM specimens. The first lens of the projector system (also called the intermediate or diffraction lens) is the third most important one. All the other lenses can be ignored, even though they magnify images. Since the objective lens is the most important, the center of the objective is acmally the optical axis, every other lenses must be aligned with it. TEM alignment starts from top to the bottom. 

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