In 1974 J. A. Panitz introduced the Field Desorption Spectrometer that incorporates a proximity focussed, spherically curved, dual channel plate detector, an 11.8 cm drift region and a 38° field of view [2].

In addition to determining the identity of a surface species producing a preselected ion-image spot as in the APFIM, it can also determine the complete crystallographic distribution of a surface species of a preselected mass-to-charge ratio. To do this suppose that instead of operating the detector continuously as usual, it is turned on for a short time coincidentally with the arrival of a preselected species of interest. This is accomplished by applying a gate pulse a time T after the evaporation pulse has reached the specimen. If the duration of the gate pulse is shorter than the travel time between adjacent species, only that surface species having the unique travel time T will be detected and its complete crystallographic distribution displayed  [18, 36].

The instrument was patented in 1975, the same year that its Imaging Atom Probe (IAP) moniker was coined by A. R. Waugh [12]. Play the Video.