Three-Dimensional Shape Measurement Beyond Diffraction Limit for Measurement of Dynamic Events

Microshape Measurement Method Using Speckle Interferometry Based on Phase Analysis

“…On the contrary, in terms of the fine structure used in this study, it is believed that it is impossible to obtain the final shape unless filtering is performed. In this study, as described above, processing using filtering technology for noise components in two different frequency bands is performed in two steps [14][15][16]. Therefore, it is possible to observe the fine structure smoothly.…”

“…In addition, a piezo element was used in the initial experiment set for achieving lateral shift [14]. However, as the shift is several tens of nanometers, although the speckle pattern data collected without horizontal shifting are virtually shifted in the computer, it was reported that the result of the virtual shift produces the same effect as the result of the shift using the piezo element [15]. Therefore, in this analysis, only one speckle pattern was captured instead of collecting two speckle patterns before and after the horizontal shift.…”

“…Speckle is currently considered a significant phenomenon in the optical field. Furthermore, speckle interferometry has been used for three-dimensional (3D) shape measurements [14,15]. A 3D structure beyond the diffraction limit of the objective lens can be measured by using the scattered light as the illumination light and by detecting the phase of the light recorded in the speckle formed by the scattered light [15].…”

“…The principle of this method [14,15] can be validated by comparing its measurement results with those of other techniques, such as atomic force microscopy (AFM), using the grating of the periodic structure as the measurement object. In this case, because the same structure exists everywhere, the same situation of the same measured object can be measured [14][15][16]. However, if only the periodic structure is measured, misunderstandings and misconceptions can emerge if the speckle interference measurement technology is not well understood.…”

Shape Measurement Method of Two-Dimensional Micro-Structures beyond the Diffraction Limit Based on Speckle Interferometry

“…For example, as shown in Figure 4a, when a diffraction grating with a period of 833 nm is measured as an SEM image, the speckle pattern also shows a fringe image with a period of 833 nm, as shown in Figure 4b, because the measurement object does not exceed the diffraction limit. This speckle pattern (SP1) is artificially shifted by three pixels (45 nm) in the x-direction on the computer memory [22], as shown in Figure 3(2), to create the speckle pattern (SP2). In this optical system, it had been confirmed that one pixel corresponds to 15 nm on the image element using a calibrated scale; therefore, it is known that three pixels correspond to 45 nm.…”