Source beam condensing systems

The situation, however, is different for the infrared spectroscopic measurements with opposed anvil cells. The source beam in commercial Fourier transform infrared spectrometers is generally focused to about 1 cm diameter at the sample, whereas the diameter of the gasket hole in the high pressure cell is only about 0.3 mm. Therefore, a source beam condensing system is required in order to obtain infrared spectra with a good signal-to noise ratio. Commercial beam condensers (4X, 6X) could, in principle, be adapted for these purposes. In practice, however, the mirrors of the... 

Microscopes used in LM are composed of a beam of visible light (photons) that represents the illumination source (probe), a system for focusing the source onto the sample (the condenser or condense glass lens), a location to place the sample or specimen, and the objective. 

Lenses are usually used with spectrometers to serve four functions (1) as a condensing system, (2) to collimate (make parallel) a light beam, (3) to focus the beam at some predetermined point, and (4) to enlarge or decrease the image size of the source. A lens may serve two or more of these functions at the same time. 

The light source (1) is a 2mW vertically polarized helium-neon laser which provides a small-diameter, coherent incident beam of 633 nm wavelength which is folded back on itself via a two-prism system (2). This directs the beam toward three measuring attenuators (3, 4, 5) a calibrating/shutter attenuator (6), a condensing lens (7), the sample compartment (8) and finally, through an optical system, to the detector. 

The two stage momentum separator used in this interface is shown schematically in Figure 3 coupled to the combination Thermospray/EI source. This device is conceptually similar to those used in other MAGIC (2) or particle beam (3,4) interfaces. However, since most of the solvent vapor is removed in the gas diffusion cell, this separator is required primarily to remove sufficient helium to allow the standard MS pumping system to achieve the good vacuum required for El operation. The performance of this device can be optimized much more readily for separating helium from macroscopic particles than when copious quantities of condensible vapors are present as in the more conventional particle beam systems. 

A system generating a primary ion beam consists of three main parts ion source, ion filter and deflector as schematically illustrated in Figure 8.5. The ion source produces primary ions with a certain kinetic energy. The ion filter purifies the primary ions and rejects unwanted ions in the primary ion beam. The purified ions are condensed to a focused beam using an electromagnetic lens. The deflector makes the focused ion beam raster on the sample surface in two orthogonal directions its function is similar to the electron beam deflector in the scanning electron microscope (SEM). 

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