Observations of the fibril mergence and bright sheet-like structures nearby the interaction region. (a1)–(a3): interaction of two groups of chromospheric fibrils (L1 and L2) and the subsequent formation of a northward-moving longer fibril (F1). Red and blue contours in (a1) mark a pair of magnetic patches saturated in ±50 G, where L1 and L2 are rooted. Two arrows in (a2) and (a3) denote the moving direction of F1. (b1)–(b3): similar process as that in (a1)–(a3). The black rectangle in (b2) denotes a bright sheet-like structure. The blue curve in (b3) shows the evolution of the flux of N. (c1)–(c3): bright sheet-like structure in the 171 Å, 304 Å, and 193 Å channels, respectively. (d): light curve of the filament main body (the rectangle region in (b1)). (e): light curves of the interaction region (the rectangle region in (c1)) in different channels. An animation of this figure is available online.