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Joined 2026-09-21 Message
Incoming links: T. J. Spencer (optical physicist)
A. Hall (optical physicist) 2026-11-05
A. Hall is a coauthor of the1999 Central Laser Facility report describing a single-shot optical correlation instrument with a charge-coupled device readout.[ref]
A Single Shot 3rd Order Cross-Correlator for Pulse Contrast and Pulse Shape Measurements by J. Collier and others. Printedpp194–195, byline and Figure2
A detector coordinate becomes a delay measurement only through measurement calibration. For an original example, suppose a known change of optical delay by200femtoseconds shifts a feature by0.80millimeters on the detector image. The calibrated scale isWith10micrometer pixel spacing, adjacent pixels represent2.5femtoseconds on that scale. A feature spanning20pixels spans50femtoseconds in the sampled delay coordinate.
This conversion does not prove that the optical apparatus resolves2.5femtoseconds. Pixel sampling, the optical response and uncertainty in the delay mapping are separate properties. A densely sampled broad response remains broad. Nor does a feature's correlation width necessarily equal the underlying pulse width, as the Gaussian pulse example in T. J. Spencer demonstrates.
The example shows why a spatially recorded third-order intensity autocorrelation requires both a calibrated coordinate conversion and an independently understood response. The numerical values above are stipulated for illustration, rather than specifications assigned to the historical instrument.