Classical McPherson 225

This classical McPherson 225 a 1.0 m focal length McPherson 15° with a hand polished, lacquered finish, circa 1967 This unit is operated in the 300 to > 5,000 Å region, with their real forte being 300 - 3000 Å (5 - 40 eV). These are popular due to its high resolution and low astigmatism. This is an ideal imaging instrument for use with microchannel plate intensified or CCD type array detectors.

This class of spectrometer is based on the principle that the grating rotates and moves along the angle bisecting the angle subtended by the slits.The rotation of the grating provides wavelength selectionwhile the movement provides focus. McPherson, Inc. built the “McPherson 15°” in 1965 and took an empirical approach to the calculable wavelength drive properties. A mechanical cam was devised and patented that simultaneously scans and focuses the desired wavelength. According to the McPherson design a mechanical sine drive / lead screw, common to all our instruments, could be used to take advantage of this systems outstanding optical properties. The elimination of the cam (designed for use with spherical gratings) permits to use varied line space gratings and other non-standard grating formats.