Toroidal mirrors

The above figures are often approximated by the simpler cylindrical or toroidal mirrors, but these are much less efficient and give significantly increased aberrations... 

Fig. 4. Experimental arrangement on the XAS instrument 8.1 at the SRS, where a slitless monochromator is used and the crystals are mechanically bent to account for the vertical divergence (0.2 mrad) of the x-rays from the source. A toroidal mirror is placed after the monochromator, which provides the focussing...

Fig. 46. Optical diagram of the Polytec MIR 160 Fourier spectrometer (No. 5b in Tables 2, 3, 4). M 1, M 2, M 5, M 6, M 7 plane mirrors M 3, M 4 paraboloid mirrors MS spherical mirror MT toroid mirrors G Globar source S high pressure Hg-lamp L He-Ne-laser IS Interferometer scanner BS beampslitter PC photo-cell D pyroelectric detector WL white light source...

Photon beam position monitors are essential to ensure that after an injection the electron beam position is adjusted to allow the SR to strike the beam line optical components in a constant way. The wavelength output from a double crystal monochromator is especially sensitive to the vertical beam position. Also, the quality of the focus, from a toroid mirror, is especially sensitive to the horizontal beam position (figures 5.18(c) and (e)). On existing machines it is necessary to recalibrate the wavelength and the focussing of a beam line optical system after each injection. 

Figure 5.17 (a) Schematic of the beam line layout on the SRS protein crystallography station 9.5. (b) A view of the toroid mirror under test. From Helliwell (1991) and reproduced with the permission of Daresbury Laboratory. 

Figure 5.18 Ray tracing study of a toroid mirror (from Brammer et al (1988) with permission), (a) Cross section of 4mrad of...

Figure 5.19 Thermal loading study of a toroid mirror (from Brammer et al (1988) with permission). The change in mirror thickness over tfee whole surface is due to thermal loading of the SRS wiggler. The vertical scale is given in micrometres, the x and y scales are in, arbitrary, computing cell units.

Light from a broad emission source is focussed by means of a ellipsoidal mirror onto a toroidal mirror and hence onto a grating. Monochromatic light, selected by the angular position of the grating, is then focussed by a spherical mirror and then by an ellipsoidal mirror onto the sample contained in a sample cell. 

However, Bonse-Hart instruments do not measure a two-dimensional pattern and the data are slit-smeared [95,96] (see Section 7.5.3). Alefeld et al. [101,102] have proposed an alternative design using focusing toroidal mirrors (FTMs), which... 

Figure 3.19 Schematic (not to scale) of the new IRENI beamline at the SRC (Madison). For clarity, only 4 out of the 12 M4 mirrors are shown in this diagram of the beamline. The first optical components are 12 identical toroidal mirrors (Ml) located 2m from the source, working in unity t o collect the available horizontal fan of radiation. A set of 12 identical paraboloidal mirrors (M3), with 250 mm focal lengths, collimate the beams and deflect them at 90° in the horizontal plane. The collimated beams are then combined and rearranged to form a 4x3 matrix by a set of 12 plane mirrors (M4) and directed by a single flat mirror to the interferometer and to the microscope. (Reprinted from ref. 105.)...

Figure 11. The Elliott toroid camera. Rays are brought to a focus by the toroidal mirror in this figure the focal length has been considerably exaggerated, normally the radius of curvature of the mirror is 20 m.

Figure 7.5 Experimental setup for the overview absorbance measurements with the ARES spectrograph (1) D2 lamp, (2) tungsten halogen lamp, (3) beam combiner, (4) mechanical shutter, (5,9) toroidal mirrors, (6) sample and blank reservoir, (7) magnetic valve, (8) flame atomizer, (10) entrance slit, (11 -14) pre-dispersing illumination optics, (15,18) spherical mirrors, (16) prism, (17) echelle grating, (19) CCD array detector, (20) Ne lamp, (R1-R5) piezo-electrically controlled rotation units...

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