The idea of stroboscopic analysis of waveforms dates back to the beginning of the century. Sampling forms the basis of DSP and also microwave test equipment and has been used extensively in network analyzers. The HP 8410 is an example of such an instrument (technically, the HP 8405 Vector Voltmeter preceded the 8410 in its use of sampling for magnitude and phase measurements).
Sampling has also been used in oscilloscopes. The first commercial sampling 'scope was the HP 185 series. This was superceded by the still incredible 1430 sampler. Tektronix followed HP by introducing the 661 and then sampling plugins, beginning with the 4S series, then the N plugin and then the 1S series, 3S and finally 7S. More recently, both Tek and HP have eliminated the use of general purpose 'scopes as the base for sampling oscilloscopes. Furthermore, the manuals are vapid.
I have put together two annotated bibliographies in preparation for writing a review paper on sampling. One bibliography is just for papers and the other is just for patents . Comments very welcome.