The polar coordinated x-ray grating spectrometer

A new principle applicable to the Rowland circle mechanisms of X-ray spectrometers is formulated, and is based on the geometry of the circle considered in terms of its polar coordinates relative to the pole of the grating. It allows continuous adjustment of the Rowland radius scanned; it confers flexibility in operation, yet simplifies construction of the instrument. A soft X-ray spectrometer, designed on the new principle, is described and covers the wavelength range 1-20 nm for concave gratings of any radius between 0.5 and 5 m. Results obtained using an electron microprobe source are presented.