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Published April 20, 2023 | public
Journal Article

Recovering density disturbance spectra from FLDI. Part 2: comparisons with previous methods


An exact analytical method for recovering density disturbance spectra in multi-frequency, multi-dimensional fields from focused laser differential interferometry (FLDI) measurements, developed in Part 1 [Appl. Opt. 62, 3042 (2023) [CrossRef https://opg.optica.org/ao/fulltext.cfm?uri=ao-62-12-3042&id=529079] ], is compared with previous methods for quantitative interpretation of FLDI. It is shown that previous exact analytical solutions can be recovered as special cases of the more general present method. It is also found that despite outwards dissimilarity, a previous approximate method that is becoming widely used can be related to the general model. It is demonstrated that the previous approach—while a suitable approximation for spatially restricted disturbance fields such as conical boundary layers it was originally applied to—does not work well in general applications. While corrections can be made, informed by results from the exact method, doing so offers no computational or analytical advantages.

Additional Information

© 2023 Optica Publishing Group. The authors gratefully acknowledge and thank Prof. Joe Shepherd at Caltech for many very valuable discussions. The doctoral thesis of the lead author [13], of which this work formed a part, was partially supported by the ONR with Dr. Eric Marineau as program officer. Funding: Office of Naval Research (N00014-16-1-2503). Data availability. Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request. The authors declare no conflicts of interest.

Additional details

August 22, 2023
October 20, 2023