Bidirectional schlieren imaging using dual-LED illumination and a lens aperture as a knife-edge

Vimod Kumar; Manish Kumar

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arXiv · 2610.04340

Bidirectional schlieren imaging using dual-LED illumination and a lens aperture as a knife-edge

Vimod Kumar·Manish Kumar

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Abstract

In this letter, we demonstrate that employing the Lens Aperture as a Knife-Edge (LAKE) with two identical LEDs has the distinct advantage of obtaining schlieren images along two cutoff orientations. It is possible to control LED brightness to obtain a desirable weighted sum of both horizontal and vertical schlieren cutoff images on each camera frames. Powering the LED sources by an affordable and programmable Arduino board enables a rapid switch between the horizontal and vertical schlieren cutoff that is exactly synced to the camera frames, resulting in crosstalk-free schlieren image sequence. Furthermore, with a little postprocessing, this monochrome image series can be easily transformed into a colorful sequence of bidirectional schlieren images.

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Vimod Kumar, Manish Kumar. 2026-10-03. Bidirectional schlieren imaging using dual-LED illumination and a lens aperture as a knife-edge. https://arxiv.org/abs/2610.04340

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