Fast and robust method for flow analysis using GPU assisted diffractive optical element based background oriented schlieren (BOS)

Ramaiah, Jagadesh; Ajithaprasad, Sreeprasad; Gannavarpu, Rajshekhar; Ambrosini, Dario

doi:10.1016/j.optlaseng.2019.105908

Cited by 13 publications

(4 citation statements)

References 39 publications

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“…However, this cost should reduce significantly in the next years. Examples of current trends in BOS research include 3D applications [6,7,[34][35][36], quantifications and/or improvement of BOS features [5,23,[37][38][39], the use of smartphones [40], and the visualization of convective indoor air flows [41]. In several of these trends, hidden grid BOS can represent a useful tool thanks to its features.…”

Section: Discussionmentioning

confidence: 99%

Hidden Grid Background Oriented Schlieren in studying convective flows

Ambrosini

Rubeis

Paoletti

et al. 2023

J. Phys.: Conf. Ser.

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In this paper, we present a new BOS (Background Oriented Schlieren), based on a hidden grid, for studying heat flows. In the setup, we record a grid-based intensity pattern whose phase map carries information about the temperature gradient. The background (undistorted) pattern is hidden in the light source. Quantitative analysis is obtained by a windowed Fourier transform approach. Some experimental results are given to demonstrate the feasibility of the technique.

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Section: Discussionmentioning

confidence: 99%

Hidden Grid Background Oriented Schlieren in studying convective flows

Ambrosini

Rubeis

Paoletti

et al. 2023

J. Phys.: Conf. Ser.

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“…From equation (4), it is clear that the phase can be computed from the unknown coefficients α 0 , α x and α y of the polynomial function. Consequently, we apply root multiple signal classification method [24,25] to estimate these unknown coefficients.…”

Section: Theorymentioning

confidence: 99%

Non-invasive deformation metrology using subspace analysis in digital holographic interferometry

Ramaiah¹,

Gannavarpu²

2021

Meas. Sci. Technol.

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For non-invasive precision measurement of deformation using digital holographic interferometry (DHI), reliable estimation of interference phase from complex fringe signal is required. This article introduces a method for estimation of interference phase in DHI. The proposed method is based on computing roots of a frequency estimation function obtained from noise subspace of the fringe signal. The main advantage of the proposed method is robustness against severe noise. In addition, the method also offers the capability of direct phase derivative estimation. The performance of the proposed method is validated using numerical simulations. Our simulation results show that even for signal to noise ratio as low as −5 dB, the proposed method offers root mean square errors of less than 1 radian for phase retrieval. The practical utility of the method for non-invasive deformation analysis is demonstrated using experimental results in DHI.

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“…Furthermore, several approaches show that BOS can be combined with other techniques, e.g. BOS velocimetry (Settles 2010), diffractive optical element based BOS (Rajshekhar and Ambrosini 2018;Ramaiah et al 2020), or reference-free digital shadowgraphy using a moving BOS background (Gardner et al 2020). The accuracy of BOS has been analyzed and optimized showing that the dynamic range is approximately 50:1; measurement errors amount to 2-3 % in full range (Raffel 2015).…”

Section: Introductionmentioning

confidence: 99%