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In this paper, we report our first-step results of high resolutionHe\,\textsc{i} 10830 \AA\ narrow-band imaging (bandpass: 0.5 {\AA}) of an M1.8class two-ribbon flare on July 5, 2012. The flare was observed with the 1.6meter aperture New Solar Telescope at Big Bear Solar Observatory. For thisunique data set, sunspot dynamics during flaring were analyzed for the firsttime. By directly imaging the upper chromosphere, running penumbral waves areclearly seen as an outward extension of umbral flashes, both take the form ofabsorption in the 10830 \AA\ narrow-band images. From a space-time image madeof a slit cutting across a flare ribbon and the sunspot, we find that the darklanes for umbral flashes and penumbral waves are obviously broadened after theflare. The most prominent feature is the sudden appearance of an oscillatingabsorption strip inside the ribbon when it sweeps into the sunspot's penumbraland umbral regions. During each oscillation, outwardly propagating umbralflashes and subsequent penumbral waves rush out into the inwardly sweepingribbon, followed by a returning of the absorption strip with similar speed. Wetentatively explain the phenomena as the result of a sudden increase in thedensity of ortho-Helium atoms in the area of the sunspot being excited by theflare's EUV illumination. This explanation is based on the observation that10830 \AA\ absorption around the sunspot area gets enhanced during the flare.Nevertheless, questions are still open and we need further well-devisedobservations to investigate the behavior of sunspot dynamics during flares.

High resolution He I 10830 \AA\ narrow-band imaging of an M-class flare. I - analysis of sunspot dynamics during flaring