## 1 Introduction
Footnote 1: See the approach deployed in [6; 7; 8; 9; 10] from Electronic Speckle Pattern Interferometry (ESPI)-based _receptances_ and in [11; 12] from Digital Image Correlation (DIC)-based ones. Among the optical--therefore contactless, not distorting because of sensors and cabling inertia--technologies, SLDV has permitted to add degrees of freedom (dofs) and discrete spatial resolution in established Noise and Vibration Harshness (NVH) approaches in broad frequency ranges, but it can be better defined as _non-native_ full-field measurement technique, due to its _scanning_ nature. SLDV has therefore become a reference in contactless measurements for standing vibrations, but not for transients, not sensing synchronously the whole mapping. SLDV is the full-field technology here adopted for the real-life _mobility_ testing of the vibrating structural part, in order to asses its applicability to these extended data processing for fatigue life estimations. Instead, the techniques based on the sensing of photons across the whole sensor matrix can be called as optical _native_ full-field measurements, or also _image_-based, with an even higher dofs' density and field-wise accuracy/continuity than that of SLDV, as proved extensively in [3; 13; 14; 15; 16; 17; 18], especially with stroboscopic ESPI. Although the latter is limited to standing vibrations in the frequency domain, ESPI can measure extremely detailed fields with a noise floor of the order of 50 nm and a ceiling of some \(\upmu\)m, exploiting the interference phase maps and the precision of the constant wavelength of the coherent laser light, modulated up to several kHz in stroboscopic acquisitions. While quality-wise unsurpassed, for broad frequency band measurements ESPI has heavy drawbacks: in the time consuming tests, in coherent lighting requirements, in recording size and environmental vibration insulation needs, all hardly met outside a specific research laboratory. Another _native_ full-field approach is that of DIC with good spatial detail (generally better than SLDV, but lower than ESPI) in the time histories of displacement maps, once proper high-speed cameras are used related to the frequency band of interest, although generally more limited in the upper frequency than SLDV; transients are acquired in the time domain with ease; furthermore, the evaluation of multiple series of correlated displacements might be computationally intensive. A relevant advantage of DIC systems is certainly in their usage flexibility--thus of increasing interest also in industrial environments--as some in-situ applications have proved, as in [19; 20; 21; 22; 23]. Concise notes about the author's experience in optical full-field measurements follow. The first hints of the TEFFMA project appeared in 20142, consolidated by more enhanced proceedings in 20153. The first works were briefly gathered in [17]; in [18], instead, extended notes on the _full-field receptances' evaluation_ followed; in [3] model updating exploited the full-field eigenshapes coming from the EFFMA. The quality of _native_ (ESPI and DIC) full-field datasets--in broad frequency band dynamic testing--was underlined in [24]. Relevant achievements for rotational4 and strain FRF high resolution maps were compared in [6]. A risk index was firstly introduced in [7] to locate the areas mostly exposed to failure in a part subjected to dynamic load, while in [28] a damaged composite panel was tested in the same perspective. Recently, in [8], ESPI-based risk map variability was addressed by _real-valued_ amplitude excitation signatures; the effect of the energy-injection location was investigated in [9]; both aspects were gathered in [10]. Although reduced--by interpolation in both spatial and frequency domains--to the more moderate resolutions of the SLDV references in the TEFFMA project, DIC-based full-field _recptances_ were used instead in [11] for the risk index mapping.