High flux medium resolution normal incidence monochromator for sunchrotron radiation

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Abstract
Based on the peculiar spatio‐optical properties of synchrotron radiation (SR) we have designed a wavelength dispersing system in the normal incidence spectral range, the entrance slit being the tranverse section of the electron bunch itself. The system can work only in conjunction with an SR source and at a given (optical) distance to the electron orbit tangent point. Our design employs very asymmetrical grating conjugates (r∼95 m; r′0.5 m). Tuning is accomplished by simple rotation of the grating. The angle between the monochromator arms is of the order of 4°; the astigmatic length of the image is very short (0.3 mm). In our design, light from the exit slit is refocused by a toroidal mirror to a spot 60 μm in diameter. The optical elements of the system are placed on a vertical plane with respect to the electron orbital plane, so that the already high degree of polarization of SR is increased to 95%. With a 600‐grove/mm grating the measured resolving power in the 1500‐Å region is of the order of 1000. The flux measured in the same spectral region is of the order of 1010 photons sec−1 Å−1, which gives a transmission factor T∼3×10−2. Some examples of utilization are given.
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