Dynamic noncontact surface profilometry using a fast eigenspace method in diffraction phase microscopy

Abstract

Dynamic measurement of surface profile is an important requirement in nondestructive testing, especially for the inspection of large samples with consecutive area scans or test objects under translation. In this paper, we propose the application of an eigenspace signal analysis method in diffraction phase microscopy for reliable and noncontact dynamic surface metrology. We also propose the inclusion of a graphics processing unit (GPU) computing framework in our method to enable fast interferogram processing for dynamics-based investigations. The practical viability of the proposed method is demonstrated for noninvasive nanoscale topography of a test target.

Nanoscale surface profile measurement using state space approach in digital holographic microscopy

“…In recent years, the Raspberry Pi computer and its camera module have found increasing utility in various optical applications, including bright-field microscopy [43], fluorescence microscopy [44], and digital holography [45][46][47]. Compared to the existing techniques which rely on sophisticated instrumentation such as spatial light modulator [13,19], scientific grade camera [23,24], precision filter assembly [21] and graphics processing unit computing workstation [22], the proposed system offers a step towards low cost imaging paradigm which could lead to simple, compact and robust experimental designs for surface profilometry investigations. Overall, the proposed work aims to synergize the state space approach with cost effective Raspberry-Pi imaging module for robust nanoscale surface profile measurement in digital holographic microscopy.…”

“…For non-invasive surface profile measurement, optical interferometric techniques such as scanning white light interferometer [5], phase shifting interferometer [6,7], Fizeau interferometer [8,9] and digital holography [10,11] have gained widespread adoption due to their non-contact operation, good resolution, and high throughput. A recent development in this domain is the advent of quantitative phase microscopy approach, where the principles of optical microscopy and quantitative phase metrology are combined, and this has spawned several techniques such as Fourier phase microscopy [12,13], Hilbert phase microscopy [14,15], digital holographic microscopy [16][17][18], spatial light interference microscopy [19,20] and diffraction phase microscopy [21][22][23][24]. Among these techniques, digital holographic microscopy has an important advantage of numerical wavefield reconstruction and refocusing of hologram images, which simplifies the experimental design.…”